Professor David Bradley

Emeritus Professor
+44 (0)1483 683771
07 BC 04

Academic and research departments

School of Mathematics and Physics.


University roles and responsibilities

  • Course Deputy Director for the MSc Programme in Medical Physics and the MSc Programme in Medical Physics


    Research interests



    David Bradley (2023)Foreword to the 5th International Forum on Advances in Radiation Physics (IFARP-5), In: Radiation Physics and Chemistry111142 Elsevier

    Over the period 28 to 29th November 2022, the Sunway University Research Centre for Applied Physics and Radiation Technologies (CAPRT) hosted an event initially planned as the 1st Sunway-Asian/ Oceania Radiation Physics Networking Workshop. We have great aspirations to emulate the best, wishing ourselves to become much like the Gordon Research Conferences (GRC), ‘dedicated to building communities that advance the frontiers of science’. The GRC is a not-for-profit organization, as is the Jeffrey Cheah Foundation that funds Sunway University. Born out of a successful competitive bid to the University, we were able to make use of a stimulus package that looked to encourage regional engagements in areas of interest to the University. That funding has been central to the success of the event, a matter recorded herein and strongly appreciated. As a result, by way of invitations, we now have an improved understanding of regional efforts taking place within the broad remit of what one might call the radiation sciences. Clearly this is work in progress, the meeting providing a forum which at the regional level is looking to help realize the greater potential of our shared aspirations, knowledge, facilities, human resource and capacity to attract funding.

    Rifqah Nurul Ihsani, Roni Rahmat, Heryanto Heryanto, Abdelmoneim Sulieman, David A. Bradley, Dahlang Tahir (2023)Functionalizing surface state of composite geopolymer concrete filler with metal (Ni or Fe) for increasing performance of X-ray shielding, In: Applied Physics A: Materials Science and Processing129(7)503 Springer

    Protection of personnel against ionising exposure is necessary to prevent occurrence of biological risks. The objective of this study is to arranged light and heavy nuclei at the surface state particle of composite geopolymer concrete when filler with metal (Ni or Fe) for X-ray shielding applications. The composite fly ash geopolymer concrete with fillers Ni and fly ash geopolymer concrete with Fe as a shield for X-ray radiation has been successfully synthesized by a simple method. The shielding composites were carried out using Fourier transform infra-red (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray mobile to determine optical properties, structural properties, surface morphology, and shielding performance. In this study shows strong linear correlation between structural properties and the effectiveness of X-ray shielding. The best composite as an X-ray radiation shield is composite concrete geopolymer with AC and Ni as a filler indicated by higher linear attenuation coefficient (μ) due to present combination between heavy and light nuclei at the surface state of particle, consequently, produce high stability structural and optical properties, and bonding characteristics. The results in this study indicated composite concrete geopolymer fly ash with AC and Ni as a filler with sharp nodule at the surface state looks like prickly ball as a new composite for X-ray shield.

    Ghada Khouqeer, A. Sulieman, F. Mayhoub, H. Salah, M. Alkhorayef, Huda Al-Mohammed, D.A. Bradley (2023)Staff occupational exposure and ambient doses resulting from patients undergoing nuclear medicine procedures, In: Radiation Physics and Chemistry212111091 Elsevier

    Ultrasound personnel can be occupationally exposed to ionizing radiation from radioisotopes during ultrasonography imaging of patients who received radioactive material. Thus, radiation safety assessment is required to ensure that the ultrasonography physicians practices conform with the international guidelines and that dose limits are not exceeded. This study aimed to measure staff exposure during ultrasound investigations of such patients who received radioactive material in molecular imaging procedures such positron emission tomography (PET) and single photon emission computed tomography (SPECT). Occupational doses, in terms of Hp (10) (deep dose), Hp (0.07) (skin dose) and ambient dose were monstered using calibrated thermos-luminescent dosimeters (TLDs) to ensure occupational doses exposures for the ultrasonographers over 1 year at King Faisal Specialist Hospital and Research Center in Riyadh, Saudi Arabia. The overall mean of Hp(10), Hp(0.07) for an annual occupational dose of 0.4 mSv and ambient dose (mSv) were (M) in ultrasound room, Hp(10) of 1.7 mSv and Hp(0.07) of 1.72 mSv in the Hot Lab, and Hp(10) of 0.4 mSv and Hp(0.07) of 0.02 mSv in the Stress Room. Occupational exposure was below the annual dose limits (20.0 mSv) for all practitioners, as well the extremities dose was below the annual dose limits of 500 mSv. In conclusion, since staff exposure which highly depends on radioisotope characteristics and protection measures can vary significantly for different personnel, continuous serial careful assessment of working conditions is recommended to ensure occupational doses exposures remain below annual limits.

    H.G. Sarhan, S.M. Saini, N.M. Bahari, D.A. Bradley, H.T. Zubair, A. Basaif, A.A. Oresegun, H.A. Abdul Rashid, N.M. Noor (2023)Performance of a Ge-doped optical fibre dosimeter for CT real-time measurements, In: Radiation Physics and Chemistry212111149 Elsevier

    This study investigates the dosimetric characteristics of a real-time radioluminescence (RL) Ge-doped optical fiber sensor, model LS-1000, providing measurement of absorbed dose in terms of counts in use of a computed tomography (CT) system. A CT dose index head phantom has been used as the reference tool. The response of the LS-1000 sensor has been compared against that of two other forms of dosimeter - a RaySafe X2 CT sensor (an ionization chamber system) and a Black Piranha CT dose profiler (a point dose solid-state detector). The three dosimeters have been irradiated in each of five available holes within the CT dose index head phantom. The results show RL response at the position of the peripheral holes of around 250 counts/gate for a gate time of 10 ms, while at the position of the central hole the response was 80 counts/gate. The maximum dose rate for the RaySafe X2 CT sensor has been found to be 5 mGy/s while that observed for the CT dose profiler was 6 mGy/s. In respect of CT applications, this trial of the luminescence device demonstrates that the germanium-doped optical fiber device may offer a promising alternative to conventional dosimeters, also allowing measurements at high accuracy and precision.

    Heryanto Heryanto, Siswanto Siswanto, Roni Rahmat, Abdelmoneim Sulieman, David A. Bradley, Dahlang Tahir (2023)Nickel Slag/Laterite Soil and Nickel Slag/Iron Sand Nanocomposites: Structural, Optical, and Electromagnetic Absorption Properties, In: ACS Omega8(21)pp. 18591-18602 American Chemical Society

    Efforts to produce microwave absorber materials thatare inexpensiveand environmentally friendly have become a means of greening the environment.The breakthrough can be focused on industrial waste and natural materialsfor functional purposes and how to enhance their performance. We successfullysynthesized nickel slag/laterite soil (NS/LS) and nickel slag/ironsand (NS/IS) nanocomposites using a simple mechanical alloying technique,and the electromagnetic (EM) wave absorption capacities of the nanocompositeswere measured using a vector network analyzer. The structural propertiesof the nanocomposites were analyzed by X-ray diffraction spectroscopy,where the results of the analysis showed that NS/IS has the largestcrystallite size (15.69 nm) and the highest EM wave absorption performance.The optical properties of the nanocomposites were determined fromtheir Fourier transform infrared spectra using the Kramers-Kronigrelation. As determined through a quantitative analysis of the opticalproperties, the distance between the longitudinal and transversaloptical phonon wavenumber positions (& UDelta;-(LO - TO) = 65cm(-1)) is inversely proportional to the reflectionloss. The surface morphologies of the nanocomposites were analyzedby scanning electron microscopy, and the particle diameters were observedby binary image and Gaussian distribution analyses. The nanocompositesurface exhibits a graded-like morphology, which indicates multiplereflections of the EM radiation, consequently reducing the EM interference.The best nanocomposite for an attenuated EM wave achieved a reflectionloss of -39.14 dB at 5-8 GHz. A low penetration depthhas implications for the electrical charge tuning of the storage andcomposite magnets. Finally, the EM absorption properties of NS/ISand NS/LS indicate a 2-mm-thick environmentally friendly nanocompositefor EM absorption.

    Abdelmoneim Sulieman, Omer Mahgoub, H Salah, Nissren Tamam, Afaf Taha, Sali Dawood, D A Bradley (2023)Assessment of patient and occupational exposure and radiation risk from cath-lab procedure, In: Applied Radiation and Isotopes202111071 Elsevier

    Due to the extended localized fluoroscopy, many radiographic exposures, and multiple procedures that might result in tissue reaction, patients and personnel received a significant radiation dose during interventional cardiology (IR) procedures. This study aims to calculate the radiation risk and assess patient and staff effective doses during IC procedures. Thirty-two patients underwent a Cath lab treatment in total. Ten Cath lab personnel, including six nurses, two cardiologists, and two X-ray technologists. Optical stimulating-luminescent dosimeters (OSL) (Al2O3:C) calibrated for this purpose were used to monitor both occupational and ambient doses. Using an automated OSL reader, these badges were scanned. The Air Kerma (mGy) and Kerma Area Products (KAP, mGy.cm2) have a mean and standard deviation (SD) of 371 ± 132 and 26052, respectively. The average personal dose equivalent (mSv) and its range for cardiologists, nurses and X ray technologists were 1.11 ± 0.21 (0.96–1.26), 0.84 ± 0.11 (0.68–1.16), and 0.68 ± 0.014 (0.12–0.13), respectively. The current study findings showed that the annual effective dose for cardiologists, nurses, and X-ray technologists was lesser than the yearly occupational dose limit of 20 mSv recommended by national and international guidelines. The patients’ doses are comparable with some previously published studies and below the tissue reaction limits.

    H. T. Zubair, D. A. Bradley, M. D. Khairina, Adebiyi Oresegun, A. Basaif, J. Othman, R. Rifiat, F. Hamidi, L. Rahman, A. Ezzadeen, S. A. Ibrahim, S. Mansor, M. Alkhorayef, H. A. Abdul-Rashid (2023)An extendable optical fibre probe survey meter for naturally occurring radioactive material (NORM) and other weak emitters, In: Scientific reports13(1)11918 Nature Research

    We have developed a radioluminescence-based survey meter for use in industries in which there is involvement in naturally occurring radioactive material (NORM), also in support of those needing to detect other weak emitters of radiation. The functionality of the system confronts particular shortcomings of the handheld survey meters that are currently being made use of. The device couples a LYSO:Ce scintillator with a photodetector via a polymer optical fibre waveguide, allowing for "intrinsically safe" inspection within pipework, separators, valves and other such component pieces. The small-diameter optical fibre probe is electrically passive, immune to electromagnetic interference, and chemically inert. The readout circuit is entirely incorporated within a handheld casing housing a silicon photomultiplier (SiPM) detection circuit and a microprocessor circuit connected to an LCD display. A 15 m long flexible PMMA optical fibre waveguide is butt coupled to an ABS plastic probe that retains the LYSO:Ce scintillator. Initial tests have included the use of lab-based mixed gamma-ray sources, measurements being made in concert with a reference conventional GM survey-meter. Characterization, via NORM sources at a decontamination facility, has shown useful sensitivity, covering the dose-rate range 0.10- to 28 µSv h −1 (R-squared 0.966), extending to 80 µSv/h as demonstrated in use of a Cs-137 source. The system is shown to provide an effective tool for detection of radioactivity within hard to access locations, in particular for sources emitting at low radiation levels, down to values that approach background.

    Z. Zakaria, M.Z. Abdul Aziz, N.H. Ishak, S. Suppiah, D.A. Bradley, N. Mohd Noor (2023)Comparison of effective atomic number, output factor, and glow curve of fabricated Ge-doped optical fibers (FGDOFs) for electron beams dosimetry, In: Radiation Physics and Chemistry212111012 Elsevier

    The present study is extended from a previous study on advanced characteristics for Fabricated Ge-Doped Optical Fibers (FGDOFs) in electron beam dosimetry with comparison in terms of Effective Atomic Number (Zeff), Output Factor (OF), and Glow Curve Analysis. Other than that, the different shapes and germanium dopant concentrations of FGDOFs were studied. Regarding Zeff, Flat Fiber (FF) showed lower Zeff than Cylindrical Fiber (CF) at a difference of ±7%. No significant difference at p > 0.05 for the of 6, -9, and 12 MeV electron energies. WinGCF software was used to deconvolute the glow curve, with the best fitting for FF and CF. Results from Glow Curve Analysis showed that the Maximum Temperature (Tmax) was energy independent for all CFs and FFs. Peak 3 (P3) was for the significantly deep holes for FF (2.3% mol; 643 μm × 356 μm), CF (2.3% mol; 481 μm), and CF (6.0% mol; 486 μm) while peak 4 (P4) for FF (6.0% mol; 620 μm × 165 μm) and CF (6.0% mol; 616 μm), respectively. Both FF (2.3% mol and 6.0% mol) have the greater sensitivity with the highest thermoluminescence (TL) signal due to the highest activation energy compared to CFs. •We investigate the fabricated Ge-doped for electron beams dosimetry.•The effective atomic number, output factor and glow curve were established.•The difference percentage for output factors is within ±5% for all fibres.•Tmax for CFs and FFs showed energy independency for P1 to P5.•2.3% mol FF showed outstanding performance with maximum PI and higher maximum TL.

    M. M. Mahfuz Siraz, Jubair A. M., M. S. Alam, Md. Bazlar Rashid, Z. Hossain, Mayeen Uddin Khandaker, D. A. Bradley, S. Yeasmin (2023)Measurement of radioactivity in soils of Karamjal and Harbaria mangrove forest of Sundarbans for establishment of radiological database, In: PloS one18(10)e0289113 Public Library of Science

    This work presents the first in-depth study of soil radioactivity in the mangrove forest of Bangladesh part of the Sundarbans. It used HPGe gamma-ray spectrometry to measure the amount of natural radioactivity in soil samples from Karamjal and Harbaria sites of the world’s largest mangrove forest. The activity concentrations of most of the 226 Ra (14±2 Bqkg -1 to 35±4 Bqkg -1 ) and 232 Th (30±5 Bqkg -1 to 50±9 Bqkg -1 ) lie within the world average values, but the 40 K concentration (370± 44 Bqkg -1 to 660±72 Bqkg -1 ) was found to have exceeded the world average value. The evaluation of radiological hazard parameters revealed that the outdoor absorbed dose rate (maximum 73.25 nGyh -1 ) and outdoor annual effective dose (maximum 0.09 mSvy -1 ) for most samples exceeded the corresponding world average values. The elevated concentration of 40 K is mainly due to the salinity intrusion, usage of fertilizers and agricultural runoff, and migration of waste effluents along the riverbanks. Being the pioneering comprehensive research on the Bangladesh side of the Sundarbans, this study forms a baseline radioactivity for the Sundarbans before the commissioning of the Rooppur Nuclear Power Plant in Bangladesh.

    Duong Thanh Tai, Hiba Omer, Le Cuong Quoc, Nguyen Xuan Hai, Van Minh Truong, Abdelmoneim Suleiman, Essam Mattar, Hind Toufig, N. Tamam, David A. Bradley (2023)An Open-Source Software for Calculating 1D Gamma Index in Radiation Therapy, In: Journal of King Saud University. Science35(10)102937

    Purpose This study was developed to create computer software for performing the gamma index comparison between measurement and Monte Carlo (MC) simulation for the percentage depth dose (PDD) and beam off-center ratio profile (OCR). Materials and methods The gamma software was built in the matrix laboratory (MATLAB) software environment. The developed software was compared with ScanDosematch and Bistromath software’s gamma evaluation to assess its accuracy. A set of reference and evaluated dose distribution, which were obtained from measurement and MC simulation, was input to the software to calculate the 1D gamma index using different criteria (i.e. 3%/3 mm, 2%/3 mm, and 2%/2 mm). Results We compared the two results of gamma index at 3%/3 mm, 2%/3 mm, and 2%/2 mm criteria, one calculated by the proposed software and one manually. The comparison showed high agreement between the proposed software and theoretical calculation. Conclusions Based on the results, we concluded that our developed software has high accuracy, compared to theoretical calculation. This software could serve as a non-commercial and open-source tool for researchers and students.

    A. Khodaei, A.N.Z. Rashed, F. Moradi, H.A. Abdul-Rashid, D.A. Bradley (2023)A review of the Geant4 simulation platform for applications involving optical-based sensing and dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)212111062 Elsevier

    Geant4 is a versatile simulation platform for numerous applications involving transport of ionizing radiation, including ionizing photons. Moreover, the physics needed for tracking optical photons is also embedded in the Geant4 simulation toolkit. From its introduction two decades ago there have been a variety of reports concerning the use of the Geant4 code in optical photons transport applications. Further to this, in particular for the interests herein, characterizations of radioluminescence radiation detectors have also been conducted. Noting the rapid development of such detectors, reliant on light collection and detection, there has been an implicit need for optimization of the different components forming the respective optical devices. Compared to ionizing radiation transport modeling less attention has been paid to this capability among the radiation physics community and Geant4 users. This review first describes in brief terms the physics built into Geant4 to provide for the transport of optical photons. This is followed by a retrospective on reported applications, discussion of the strengths and deficiencies of optical transport analyses by Geant4 and contemplation of possible future applications. •Geant4 simulation platform also has the capability to simulate optical photons besides simulating the ionizing photons.•Description of Geant4 physics for transport of optical photons and ionizing photons.•Current and potential applications simulated using Geant4 for tracking optical photons.•Strengths and deficiencies of optical transport analyses by Geant4.

    Mayeen U Khandaker, Nurul S B Zayadi, Siti Fairus A Sani, David A Bradley, Hamid Osman, Yasser Alzamil, Meshari Almeshari, M I Sayyed, Abdelmoneim Sulieman (2023)Norm in cultivated honey in Malaysia and concomitant effective dose to consumers, In: Radiation Protection Dosimetry199(18)pp. 2174-2178 Oxford University Press

    Present study concerns the radiological character of Malaysian honey. A total of 18 samples (representative of the various most common types) were obtained from various honey bee farms throughout the country. Using a high-purity germanium γ-ray spectroscopic system, the samples were analysed for the naturally occurring radionuclides 226Ra, 228Ra and 40K. The respective range of activities (in Bq/kg) was: 3.49 ± 0.35 to 4.51 ± 0.39, 0.99 ± 0.37 to 1.74 ± 0.39 and 41.37 ± 3.26 to 105.02 ± 6.91. The estimated associated committed effective doses were derived from prevailing data on national consumption of honey, the annual dose being found low compared with the UNSCEAR reference dose limit of 290 μSv y−1. The estimated threshold consumption rate for honey indicates a maximum intake of 339 g/d, which poses an insignificant radiological risk to public health; however, the total dietary exposure may not, the guidance level of 290 μSv y−1 being applicable to dietary intake of all foodstuffs. The study is in support of the cultivation of a healthy lifestyle, acknowledging prevailing radioactivity within the environment.

    Mayeen Uddin Khandaker, Ali Taheri, David Andrew Bradley (2023)A systematic review on the silica fibre thermoluminescence dosimeters for medical applications, In: Journal of Radioanalytical and Nuclear Chemistry Springer

    Silica fibre thermoluminescence (TL) dosimeters have demonstrated versatility in medical and industrial, offering high spatial resolution, sensitivity, water resistance, and insensitivity to electromagnetic fields. A systematic review focusing on the medical applications of silica fibre TLDs is conducted, highlighting the potential of these materials in medical radiation dosimetry. Despite some limitations, such as non-linearity at low energies and relatively high signal fading, silica fibre TL dosimeters have shown excellent TL performance. However, their application in clinical practice is yet to be established since the TL responses for a wide range of doses and energies are not accurately certified yet.

    Amal Alqahtani, Abdulaziz Alhazmi, M. Alkhorayef, Abdelmoneim Sulieman, S. Aldawood, D.A. Bradley (2023)Borosilicate glass media for neutron sensing, In: Radiation Physics and Chemistry212111064 Elsevier

    This work using a borosilicate glass medium seeks to detect photoneutrons generated by a medical linear accelerator. The studies involved an Elekta Infiniti accelerator located in the Oncology Centre, Medical City, Riyadh, the neutrons resulting from interactions at above-threshold therapeutic photon energies. The borosilicate detectors were produced from microscope glass slides of nominal thickness 1.0 mm, the latter made into square segments of area 0.6 × 0.6 cm2, a size capable of being accommodated within the planchette of the thermoluminescent (TLD) Reader (Harshaw 600). With some 4% boron in the coverslip glass and the abundance of 10B being 19.8%, thermalised neutrons 10B(n,α)7Li interactions offer a cross-section that can achieve a value as large as 3837 b. Apart from interactions in boron, of additional note is that 2H(γ,n)1H and 9Be(γ,n)8Be are two further photoneutron reactions, giving rise to particularly low threshold energies at 2.226 and 1.666 MeV, respectively. The presence of natural carbon in the present borosilicate samples has been measured to be 1.3%. Accordingly, with the abundance of 13C in natural carbon being 1.109% this would appear to be of very little interest herein. Moreover, compositional measurements made on the borosilicate coverslip glass indicates 9.40 Na. The induced activity in the glass falls to some 25% 30 h post-irradiation, a delay time beyond which readout can subsequently be conducted. •Borosilicate glass media for neutron sensing was developed.•Photoneutron was generated using an Elekta Infiniti linear accelerator beams.•Neutron activation of nuclides within the expanse of the beam should be considered.

    Mahfuza Begum, Huda I. Almohammed, A.K.M. Mizanur Rahman, H.A. Abdul-Rashid, Z. Yusoff, Zuhal Y. Hamd, Mayeen Uddin Khandaker, D.A. Bradley (2023)Collapsed photonic crystal fibre thermoluminescence dosimetry for external beam radiotherapy, In: Journal of Radiation Research and Applied Sciences16(1)100526 Elsevier

    In measuring exposure to ionizing radiation various detectors and techniques have been developed. Current investigation is of key TL dosimetric responses of Ge-doped collapsed photonic crystal fibre (PCF), a form offering the advantage of greater sensitivity compared to more conventional single-mode optical fibers. The PCF samples that have been studied herein have been used to obtain external photon beam percentage depth doses (PDD), elevated sensitivity being desirable in providing a basis for the capture of the range of doses. Using a linac operated at 6 and 10 MV, the results show a favourable comparison with ionization chamber values (typically to within 5%). Threshold dose, reproducibility, and dose-rate dependency have also been characterized.

    Mawya Khafaji, Rashid Barnawi, Salma Amoudi, Hassan Gabbani, Rayan Alhazmi, Rayan Ahyad, Khalid Alsafi, Khuld Saeedi, Hassan Salah, Nissren Tamam, David Bradley, Sarah Albahiti, Abdelmoneim Sulieman (2024)Diagnostic reference levels for common pediatric computed tomography studies: A retrospective study, In: Radiation physics and chemistry (Oxford, England : 1993)215111372 Elsevier

    With the rapid increase in computed tomography (CT) examinations among pediatric patients, the concern about the effects of radiation exposure in this population has increased. Therefore, it is necessary to measure and regulate radiation exposure, which can be done using diagnostic reference levels (DRLs). This study aimed to calculate typical values for common pediatric studies at the radiology department of King Abdulaziz University Hospital Jeddah, Saudi Arabia. For a single institute, these are calculated as the median of computed tomography dose index (CTDIvol, mGy) or dose length product (DLP, values. Pediatric patient data from January 2015 to December 2020 were collected, including CT examinations, dose descriptors, imaging protocols, and scanning parameters. A total of 8717 radiological studies were included in the sample. They were categorized into three age groups; more than half of the 5102 (58.5%) belonged to Group 1 (0–5 years), 1790 (20.5%) were in Group 2 (6–10 years), and 1826 (20.9%) were in Group 3 (11–15 years). Brain CT angiogram, non-enhanced brain CT, and Internal Auditory Canal (IAC) CT had the highest mean CTDI Vol and DLP, while virtual bronchoscopy contrast-enhanced chest and neck CT angiography had the lowest mean CTDI Vol. The values of DRLs in the current study were approximately lower than and comparable with those reported in other studies.

    H. Salah, A. Sulieman, M. Alkhorayef, E. Alkhybari, D.A. Bradley (2024)Evaluation of personal dose equivalents during positron emission tomography and computed tomography imaging, In: Applied radiation and isotopes203111078 Elsevier Ltd

    This study aimed to evaluate the annual occupational radiation exposure of technologists during PET/CT imaging in 2020 and 2021. Eleven nuclear medicine technologists were monitored at the PET/CT department. The personal dose equivalents (PDEs) for staff members, measured in terms of Hp (10) and Hp (0.07), were assessed annually, considering both deep and surface doses. PDEs were quantified using a thermoluminescent detector (LiF:Mg:Ti)). The average and range of PDEs and extremity doses (mSv) for the technologists were as follows: 4.5 (0.1–13.4) for Hp (10), 4.63 (0.1–13.9) for Hp (0.07), and 2.5 (0.2–17.5) for extremity, respectively. The results indicated that staff members are exposed to high-energy gamma rays while preparing radiopharmaceuticals, injections, and image acquisition. Therefore, proper handling of radiopharmaceuticals and patient management during the acquisition of parameters are crucial for maintaining the occupational dose within the defined limit. •Occupational doses were measured using calibrated Thermo-luminescent dosimeters (TLD).•The annual effective dose for PET-CT personnel were found to be below the recommended dose limits.•Staff are exposed to avoidable radiation doses.

    H. I. Al-Mohammed, A. Sulieman, Fareed H. Mayhoub, Hassan Salah, Celestino Lagarde, M. Alkhorayef, Ali Aldhebaib, C. Kappas, D. A. Bradley (2021)Occupational exposure and radiobiological risk from thyroid radioiodine therapy in Saudi Arabia, In: Scientific reports11(1)pp. 14557-14557 NATURE PORTFOLIO

    Worldwide, thyroid cancer accounts for some 10% of total cancer incidence, most markedly for females. Thyroid cancer radiotherapy, typically using I-131 (T-1/2 8.02 days; beta (-) max energy 606 keV, branching ratio 89.9%), is widely adopted as an adjunct to surgery or to treat inoperable cancer and hyperthyroidism. With staff potentially receiving significant doses during source preparation and administration, radiation protection and safety assessment are required in ensuring practice complies with international guidelines. The present study, concerning a total of 206 patient radioiodine therapies carried out at King Faisal Specialist Hospital and Research Center over a 6-month period, seeks to evaluate patient and occupational exposures during hospitalization, measuring ambient doses and estimating radiation risk. Using calibrated survey meters, patient exposure dose-rate estimates were obtained at a distance of 30-, 100- and 300 cm from the neck region of each patient. Occupational and ambient doses were measured using calibrated thermoluminescent dosimeters. The mean and range of administered activity (AA, in MBq) for the thyroid cancer and hyperthyroidism treatment groups were 4244 +/- 2021 (1669-8066), 1507.9 +/- 324.1 (977.9-1836.9), respectively. The mean annual occupational doses were 1.2 mSv, that for ambient doses outside of the isolation room corridors were found to be 0.2 mSv, while ambient doses at the nursing station were below the lower limit of detection. Exposures to staff from patients being treated for thyroid cancer were less compared to hyperthyroidism patients. With a well-defined protocol, also complying with international safety requirements, occupational exposures were found to be relatively high, greater than most reported in previous studies.

    Muhammad Riaz, Amrina Suleman, Pervaiz Ahmad, Mayeen Uddin Khandaker, Amal Alqahtani, David A. Bradley, Muhammad Qayyum Khan (2022)Biogenic Synthesis of AgNPs Using Aqueous Bark Extract of Aesculus indica for Antioxidant and Antimicrobial Applications, In: Crystals (Basel)12(2) Mdpi

    Nanotechnology has received a lot of attention from the scientific community because of the greater surface-to-volume ratio of nanomaterials, which phenomenally increases their efficacy in practical applications. Among the various synthesis techniques, the biogenic or green synthesis of nanomaterials shows advantages over other techniques such as physical, chemical, etc. This study reports the biogenic synthesis of silver nanoparticles (AgNPs) using aqueous bark extract of Aesculus indica. The as-synthesized NPs were characterized by UV-visible, FT-IR, XRD, and SEM, and then tested for their antioxidant and antimicrobial potency. We have identified phenols, flavonoids, tannins, saponins, and carbohydrates in the bark extract of A. indica. The extract-loaded-AgNPs showed the highest inhibition for Staphylococcus aureus (28.0 mm), Pseudomonas aeruginosa (17.66 mm), Escherichia coli (14.33 mm), Acetobacter serratia (14.00 mm), and Klebsiella pneumoniae (12.33 mm). The methanolic bark extract inhibited S. aureus (24.33 mm), P. aeruginosa (10.66 mm), E. coli (11.33 mm), A. serratia (9.66 mm), and K. pneumoniae (11.66 mm). Aqueous bark extract inhibited S. aureus (22.33 mm), P. aeruginosa (8.33 mm), E. coli (9.33 mm), A. serratiaa (8.33 mm), and K. pneumoniae (9.66 mm). Its aqueous extract showed the highest antioxidant potency; IC50 (0.175 mu g/mL) followed by the methanolic extract; IC50 (0.210 mu g/mL) and extract-loaded nanoparticles; IC50 (0.901 mu g/mL). Our findings provide meaningful interest for antioxidant, anti-microbial applications of, and AgNPs synthesis by, aqueous bark extract of A. indica.

    M.T. Chew, B. Jones, M. Hill, D.A. Bradley (2021)Radiation, a two-edged sword: From untoward effects to fractionated radiotherapy, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    Radiations in medicine cover a wide range of applications, predominantly in diagnostic imaging and radiotherapy, encompassing photons (x- and γ-rays) and particle radiation, as well as with the use of liquid sources in nuclear medicine focusing on physiological functional imaging, tumour detection or targeted radiotherapy. The biological interactions of ionizing radiation leads naturally to questions of benefits and risk following dose exposures. The inherent properties of ionizing radiation in sterilising dividing cells can offer immense benefits with respect to tumour control, but radiation can also deliver potential harm in the form of normal tissue toxicity or carcinogenesis. The advances in radiation technology, offering accurate and reliable dose delivery, in concert with greater understanding of the underpinning radiobiological effects are creating an ever-growing ability to extract maximum benefit and minimise risk. The radiobiological effects fall broadly under the headings of mutagenesis, chromosomal aberrations, radiation induced genomic instability and cell death. The enormity of evidence derived from these underlie the mechanism of the six Rs of controlled radiotherapy: repair, repopulation, reoxygenation, redistribution, radiosensitivity and most recently, remote bystander cellular effects (including low dose hyper-radiosensitivity, adaptive response, hormesis, abscopal effect and immune response). Herein, we seek to discuss how such understanding leads to optimised radiotherapy. •Radiation in medicine is used primarily for diagnosis and radiotherapy.•Ionizing radiation beneficial and detrimental effects.•The 6 Rs of radiotherapy.

    M.M. Mahfuz Siraz, Jubair Al Mahmud, M.S. Alam, Md. Bazlar Rashid, Zakir Hossain, Mayeen Uddin Khandaker, D.A. Bradley, M.M.H. Miah, B. Alshahrani, S. Yeasmin (2023)Risk assessment of naturally occurring radioactivity in soil adjacent to a coal-fired brick kiln, In: Radiation physics and chemistry (Oxford, England : 1993)209 Elsevier Ltd

    Being aware of the potential health effects brought on by exposure to radionuclides, besides chemical and air pollution, produced by coal-fired brick kilns, first-ever measurements of terrestrial radionuclides were performed in the topsoil sampled from the surrounding of a randomly chosen coal-fired brick kiln operating at the outskirts of megacity Dhaka, Bangladesh. By employing the HPGe gamma-ray spectroscopy, the activity concentrations of 226Ra, 232Th, and 4 K was found to be in the range of (19.2 ± 2.7–54 ± 7.0) Bq/kg, (33 ± 5.3–68 ± 9.5) Bq/kg, and (360 ± 43–540 ± 65) Bq/kg respectively, where almost all the values of 40 K, 232Th; and some of the values of 226Ra exceeded the corresponding world average values. Possible causes of the elevated level of radionuclides include the deposition of bottom ash in lowlands, the accumulation of fly ash in soils, and the fallout of fine particles that absorb the minerals released from the coal burning process. 137Cs was also found in two samples that might indicate contamination of the feed coal. Most of the outdoor absorbed dose rates, some internal absorbed dose rates, annual effective dose, gamma level index and excess lifetime cancer risk surpass the worldwide average. According to these hazard parameters, there are health risks to the brick kiln workers and the populace who consumes food crops produced in the studied agricultural soils. The present quantitative measurements urge the municipal authorities to manage and monitor the discharge of fly ash from the brick kilns and take precautionary actions to reduce unwanted health hazards. It also demands to monitor of the human health of workers and residents near the brick kilns. •First-ever radionuclide measurement in soil sampled from coal-fired brick kiln.•Elevated 226Ra, 232Th and 40 K activity concentrations were observed.•Most of the radiological hazard parameters surpass the worldwide average.•The outcomes will be used as a radiological baseline data.

    Norfadira Binti Wahib, Mayeen Uddin Khandaker, S. F. Abdul Sani, K. S. Al-mugren, D. A. Bradley, A. Sulieman, Mohammad Rashed Iqbal Faruque, M. I. Sayyed (2020)The potential use of car windscreens for post-accident dose reconstruction in the periphery of nuclear installations, In: Applied sciences10(20)pp. 1-14 Mdpi

    Cars of a variety of brands are usually parked at a fixed but increasing distance in the periphery of nuclear installations. Herein we focus on the potential use of car windscreens for post-accident dose reconstruction from unplanned nuclear events and natural disasters, also in regard to unexpected events arising during large-scale use of radioactive and nuclear materials. The situation requires identification of analytical techniques that could both readily and reliably be used to assess absorbed dose, sufficient to prompt remedial action where necessary. Samples from three widely used car brands-Honda, Toyota and Proton-are studied in respect of their thermoluminescence (TL) yield. Key TL dosimetric features in the gamma-ray dose range of 1-100 Gy are examined. An ERESCO model 200 MF4-RW X-ray machine has also been used for energy response studies; a Harshaw 3500 TLD reader equipped with WinREMS software was used for the luminescence measurements. All brands exhibit linearity of TL yield versus dose, the samples from Honda showing the greatest response followed by that of the Toyota and Proton brands. The marked energy dependence reflects the effect of the strongly Z-dependent photoelectric effect. Signal fading was investigated over a period of 28 days, the Toyota and Proton brand windshield glass showing a relatively low loss at 52.1% and 52.6% respectively compared to a 56.7% loss for that of the Honda samples. This work forms the first such demonstration of the potential of car windshield glass as a retrospective accident dosimeter.

    Hassan Salah, Fareed H. Mayhoub, A. Sulieman, M. Abuzaid, H. I. Al-Mohammed, M. Alkhorayef, D. A. Bradley (2020)Fluoro-D-glucose (18F-FDG) PET/CT and patient effective dose, In: Radiation physics and chemistry (Oxford, England : 1993)173 Elsevier

    In the present study, patient exposures Evaluations herein concern patient exposures (positron and gamma-rays) that result from fluoro-D-glucose PET and CT were investigated and radio-carcinogenic risks estimated. The six-month study, conducted at King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia, included a total of 636 patients (lymphoma = 187, nasopharyngeal carcinoma = 82, thyroid = 30 and others = 337). Patient effective dose estimations were made from administered radioactivity (AA) and CT exposures (General Electric (GE) PET/CT VCT), the mean and range of AA (in MBq) and effective dose (in mSv) were respectively: lymphoma 433.9 +/- 70.6 (297.5-735.9) and 8.2 +/- 1.3 (5.7-13.9); nasopharyngeal carcinoma 417.7 +/- 55.9 (325.6-547.6) and 7.9 +/- 1.1 (6.2-10.4); thyroid 450.1 +/- 71.4 (344.1-566.1) and 8.6 +/- 1.4 (6.5-10.8). In the same units, the mean and range of AA and effective dose for other procedures were 421.6 +/- 58.3 (283.4-606.8) and 8.0 +/- 1.1 (5.4-11.5), respectively. The mean and range of the tube current-time product (mAs) for the CT procedures were 30 (8.2-42.4). A constant tube voltage of 120 kVp was used for all patient procedures. On average, CT contributed 73% to patient effective doses, suggesting that optimisation of CT acquisition parameters are vital in seeking effective dose reduction. Patient effective doses were found to be a little above that of previous studies.

    Musa Joya, Zabihullah Stanikzai, Isa Akbarzadeh, Somayyeh Babaloui, David.A. Bradley, Shakardokht M. Jafari (2020)Prevalence of cancers diagnosed in Jamhuriyat Hospital, Kabul, Afghanistan, In: Heliyon6(3)pp. e03603-e03603 Elsevier Ltd

    Throughout the world, there exists a clear need for the maintenance of cancer statistics, forming an essential part of any rational programme of cancer control, health-care planning, etiological research, primary and secondary prevention, benefiting both individuals and society. The present work reports only on the prevalence of cancers in the Oncology Department of Jamhuriyat Hospital, Kabul, Afghanistan following several decades of war. A quantitative retrospective cross-sectional study was conducted using the medical records of patients diagnosed and treated from October 2015 to December 2017. Data includes information on gender, age, economic status, address and types of cancer diagnosed. The data was transferred to a customized form and analysed using Microsoft Excel program to classify cancer types. The total number of patients with completed documents were 1025. Of these, 403 (39.3%) were male and 622 (60.7%) female. Most of the patients were in the age range of 20–70 years old. The most common cancers in women were breast cancer (45.8%), followed by oesophagus (12.5%), colorectal (4.8%), Non-Hodgkin Lymphoma (4.7%), sarcoma (4.7%), ovary (3.8%), both stomach and liver (2.6%) and cervix uteri (1.9%). Contrarily to men, esophageal cancer was highest (21.8%), followed by stomach (12.2%), Non-Hodgkin Lymphoma (9.4%), sarcoma (8.9%), gastroesophageal junction (8.9%), colorectal (8.6%), Hodgkin lymphoma (4.7%), testis (4.2%), liver (3.2%), lung (2.7%) and Nonmelanoma skin squamous cell carcinoma 9 (2.2%). Results showed that the most frequent cancers among Afghans were breast and oesophagus. The most common cancer in men was oesophagus and stomach at the age range of 50–70 years while in women, breast and oesophagus cancers were common and within the age range of 25–65 years old. Cancer research; Epidemiology; Public health; Oncology; Women's health; Oncology; Afghanistan; Cancer prevalence; Kabul Jamhoriyat hospital.

    A Sulieman, H Adam, A Elnour, N Tamam, A Alhaili, M Alkhorayef, S Alghamdi, Mayeen Khandaker, D A Bradley (2021)Patient radiation dose reduction using a commercial iterative reconstruction technique package, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier BV

    With 75.4% of the effective doses from imaging estimated to result from computed tomography (CT), it is the leading source of medical radiation. This important observation links with a further estimate that some 2% of all cancers are a result of medical imaging exposures. Acknowledging justification and optimization to be key towards preventing unnecessary radiation exposure, present study aims to investigate radiation exposures reduction for patients undergoing multiphase CT abdomen. Study was made of 111 CT examinations, use being made of two imaging protocols. Of these cases, 55 (49.5%) were obtained using a standard imaging protocol, the remainder being studied using the pure 3D SureExposure™ low-dose technique to obtain a complete abdomen multi-phase examination. Image quality was the subject of blind analysis by two experienced radiologists. For the standard imaging protocol, the mean and standard deviation for CTDIvol and DLP were respectively 7.2 ± 2.3 mGy and 1325 ± 605 mGy cm. For the pure 3D SureExposure™ low-dose technique the respective values were 5.2 ± 1.6 mGy and 812 ± 157 mGy cm. With an achieved mean dose reduction of up to 48%, use of the low dose techniques offers appreciable potential for dose saving without affecting the image quality.

    Thanh-Nghia Nguyen, Thanh-Tai Duong, Hiba Omer, Abdelmoneim Sulieman, David A. Bradley (2023)The Design and Construction of a 12-Channel Electrocardiogram Device Developed on an ADS1293 Chip Platform, In: Electronics (Basel)12(11)2389 Mdpi

    An accurate and compact electrocardiogram (ECG) device will greatly assist doctors in diagnosing heart diseases. It will also help to address the increasing number of deaths caused by heart disease. Accordingly, the goal of the project is to design and construct an easy-to-use compact 12-lead electrocardiogram device that communicates with a computer to create a system that can continuously monitor heart rate and which can be connected to allied medical systems. The design is based on an ECG receiver circuit utilizing an IC ADS1293 and an Arduino Nano. The ADS1293 has built-in input Electromagnetic Interference (EMI) filters, quantizers, and digital filters, which help in reducing the size of the device. The software has been created using the C# programming language, with Windows Presentation Foundation (WPF), aiding the collection of the ECG signals from the receiving circuit via the computer port. An ECG Multiparameter Simulator has been used to calibrate the ECG device. Finally, a plan has been developed to connect the arrangement to health systems according to HL7 FHIR (Health Level Seven Fast Healthcare Interoperability Resources) through Representational State Transfer Application Programming Interface (Rest API). The ECG device, completed at the cost of U$169 excluding labor, allows for the signal of 12 leads of ECG signal to be obtained from 10 electrodes mounted on the body. The processed ECG data was written to a JSON file with a maximum recording time of up to three days, managed by a Structured Query Language Server (SQL) Server database. The software retrieves patient data from electrical medical records in accordance with HL7 FHIR standards. A compact and easy-to-use ECG device was successfully designed to record ECG signals. An in-house developed software was also completed to display and store the ECG signals.

    Eltayeb Osman, A. Sulieman, Khalid Alzimami, N. Tamam, Layal K. Jambi, E. Babikir, Amr A. Abd-Elghany, M. Abuzaid, Hiba Omer, D.A. Bradley (2021)Radiation exposure during therapeutic cardiac interventional procedures, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier Ltd

    The purpose the current work were to assess the radiation exposure given to patients during percutaneous coronary interventions (PCI), pacemaker (PM) and coronary angiography (CA), procedures. In total, 419 procedures were carried out in 4 specialized hospitals. Calibrated Kerma area product meters were used to quantify the patient doses. Effective dose was extrapolated using the national radiological protection board (NRPB) software program. The mean KAP (Gy.cm2) per procedure were 8.6, 6.2 and 5.6 for PCI, PM, and CA procedures, respectively. While in that order, e mean and Entrance Surface Air Kerma (ESAK, mGy) per procedure were 705.9,509, and 464.7 for PCI, PM, and CA. Patients’ doses is below the level of the deterministic effects and the effective dose per procedure is low. Patients radiation doses is lowest compared to the previous studies. •Patients' radiation doses were monitored during cardiac catheterization procedures.•The patient's doses were measured using a Kerma area product meter (KAP).•The variances in radiation doses incurred during PCI were greater than the variance in doses incurred in CA and pacemaker.•DRL values derived in this study were comparable with values reported in international literature.

    Md. Refat Jahan Rakib, Y. N. Jolly, Christian Ebere Enyoh, Mayeen Uddin Khandaker, M. Belal Hossain, Shirin Akther, Abdullah Alsubaie, Abdulraheem S. A. Almalki, D. A. Bradley (2021)Levels and health risk assessment of heavy metals in dried fish consumed in Bangladesh, In: Scientific reports11(1)pp. 14642-14642 Nature Publishing Group UK

    As a cheap source of high-quality protein, healthy fats and essential nutrients, dried fish is a common item in the daily diet of the Bangladesh populace. In this study, ten types of widely consumed dried fish ( H. neherius, T. lepturu, P.chinensis, P. affinis, A. mola, P. microdon, I. megaloptera, C. dussumieri, L. calcarifer, and G. chapra ) were analyzed for Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Hg, Pb, Ni and As by using an Energy Dispersive X-ray Fluorescence (EDXRF) technique. The concentration of the studied metals was found in the order Fe > Zn > Hg > Cu > Se > Cr > Mn > Co > Rb > Pb, while As and Ni were below the limit of detection. All fish species showed moderate to high pollution, where the species H. Neherius and P. Chinensis are the most and least polluted ones, respectively. The probable source of contamination is the leaching from the drying pans into the fish samples, atmospheric deposition, anthropogenic contamination, etc. of the water body where these fish were harvested. The calculated hazard index for the general population was below the maximum limiting value (i.e., 

    Entesar Zawam Dalah, Abdulmunhem Obaideen, Sabaa Anam, Khalid Alzimami, Layal Khalid Jambi, David A Bradley (2022)Gender based lung cancer risks for symptomatic coronary artery disease patients undergone cardiac CT, In: PloS one17(4)pp. e0265609-e0265609

    We estimate the lifetime attributable risk (LAR) of lung cancer incidence in symptomatic Coronary Artery Disease (CAD) patients receiving enhanced Coronary Computed Tomography Angiography (CCTA) and the unenhanced Computed Tomography Calcium Scoring (CTCS) examination. Retrospective analysis has been made of CCTA and CTCS data collected for 87 confirmed CAD adult patients. Patient effective dose (E) and organ doses (ODs) were calculated using CT-EXPO. Statistical correlation and the differences between E and ODs in enhanced CCTA and unenhanced CTCS were calculated using the Pearson coefficient and Wilcoxon unpaired t-test. Following BEIR VII report guidance, organ-specific LARs for the cohort were estimated using the organ-equivalent dose-to-risk conversion factor for numbers of cases per 100,000 patients exposed to low doses of 0.1 Gy. Significant statistical difference (p

    Md. Refat Jahan Rakib, Sultan Al Nahian, María B. Alfonso, Mayeen Uddin Khandaker, Christian Ebere Enyoh, Fauziah Shahul Hamid, Abdullah Alsubaie, Abdulraheem S. A. Almalki, D. A. Bradley, Hamidreza Mohafez, Mohammad Aminul Islam (2021)Microplastics pollution in salt pans from the Maheshkhali Channel, Bangladesh, In: Scientific reports11(1)pp. 23187-23187 Nature Publishing Group UK

    Microplastics (MP) were recognized as an emergent pollution problem due to their ubiquitous nature and bioaccumulative potential. Those present in salt for consumption could represent a human exposure route through dietary uptake. The current study, conducted in Bangladesh, reports microplastics contamination in coarse salt prepared for human consumption. Sea salt samples were collected from eight representative salt pans located in the country's largest salt farming area, in the Maheshkhali Channel, along the Bay of Bengal. Microplastics were detected in all samples, with mean concentrations ranging from 78 ± 9.33 to 137 ± 21.70 particles kg −1 , mostly white and ranging in size from 500–1000 µm. The prevalent types were: fragments (48%) > films (22%) > fibers (15%) > granules and lines (both 9%). Fourier transform mid-IR and near-IR spectra (FT-MIR-NIR) analysis registered terephthalate (48%), polypropylene (20%), polyethylene (17%), and polystyrene (15%) in all samples. These results contribute to the MP's pollution knowledge in sea salts to understand and reduce this significant human exposure route and environmental pollution source in the future.

    H.G. Sarhan, S.M. Saini, N.M. Bahari, D.A. Bradley, H.T. Zubair, A. Basaif, A.A. Oresegun, H.A. Abdul Rashid, N. M. Noor (2023)Real-time germanium-doped optical fibers for clinical computed tomography dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)209 Elsevier Ltd

    In studies focusing on the practice of clinical computed tomography (CT) a particular concern has been that of delivering unnecessary dose to patients and with it the added risk for radiation-induced cancers. For a CT system, present work has investigated the dosimetric characteristics of a Ge-doped optical fiber real-time dosimetry system (model LS-2000, Lumisyns), measuring beam quality, exposure linearity and exposure duration accuracy. For comparison, the study has used a RaySafe X2 test device (Unfors RaySafe) and a Black Piranha (RTI) QA meter. Irradiations were made using a Somatom Definition Flash dual-source 128-slice CT scanner (Siemens Healthcare). The LS-2000, RaySafe X2, and Black Piranha sensors were exposed to beams energized at accelerating potentials ranging from 80 to 140 kVp, with tube current-time products from 50 to 300 mA, and exposure durations from 750 to 2000 ms. Constant signal responses from the LS-2000 have been obtained, measured in respect of beam quality, exposure linearity, and time accuracy. In respect of accuracy of beam quality, the RaySafe X2 and Black Piranha maximum deviations were 1% and 5%, respectively; the coefficients of linearity of RaySafe, Black Piranha and LS-2000 are 1%, 0.4% and 1.4%, respectively; the maximum deviation for the time accuracy test for the three sensors are 0.5%, 2% and 1.3%, respectively. Evaluation of the LS-2000 real-time dosimetry system with a Ge-doped optical fiber scintillator points to potential for its use in clinical CT dosimetry. •We investigate the real-time Ge-doped for clinical computed tomography (CT).•The comparison has been made used of Unfors and RTI QA meters.•The beam quality, exposure linearity and exposure duration accuracy were established.•The LS-2000 shows good potential for use in Clinical CT dosimetry.

    Jubair Al Mahmud, M. M. Mahfuz Siraz, Mohammad Shafiqul Alam, Sudeb Chandra Das, David Andrew Bradley, Mayeen Uddin Khandaker, Shinji Tokonami, Afroza Shelley, Selina Yeasmin (2023)A study into the long-overlooked carcinogenic radon in bottled water and deep well water in Dhaka, Bangladesh, In: International journal of environmental analytical chemistryahead-of-print(ahead-of-print)pp. 1-13 Taylor & Francis

    Radon ( 222 Rn), a radioactive and gaseous progeny of Uranium ( 238 U) decay series, accounts for almost 50% of the total background radiation in our dwelling environment. Inhalation and ingestion of radon in excessive amounts pose serious health effects to humans. The first-ever measurement of radon concentration in commercial bottled water available in Dhaka city and deep well water samples from the campus of the University of Dhaka was carried out using the RAD7 Radon monitoring system. The concentration of radon in the bottled water ranged from 0.11 Bq/L to 1.30 Bq/L with a mean of 0.59 Bq/L, and the deep well water showed a mean of 4.88 Bq/L with a range of 3.02 Bq/L to 5.98 Bq/L. All twenty-five samples of water had radon concentrations within the recommended limits of USEPA and WHO. The mean annual effective doses from radon in bottled water and deep well water were evaluated to be 0.126 µSv/y and 12.481 µSv/y, respectively. Although the calculated doses indicate the least potential risk according to WHO and UNSCEAR, however, it is expected that the present results play an important role in setting up a national guideline for radon in drinking water, and the monitoring of radon for the safety of public health.

    Siti Norbaini Sabtu, S. F. Abdul Sani, D. A. Bradley, L. M. Looi, Z. Osman (2020)A review of the applications of Raman spectroscopy for breast cancer tissue diagnostic and their histopathological classification of epithelial to mesenchymal transition, In: Journal of Raman spectroscopy51(3)pp. 380-389 Wiley

    Breast cancer is one of the leading cancers in women worldwide. Notwithstanding the clear advances being made in treatment, early diagnosis of the disease can certainly be expected to reduce morbidity and mortality. With increasing evidence of the role of epithelial to mesenchymal transition (EMT) in tumour progression, early detection of this phenomenon is suggested to be important given that the majority of breast cancer deaths are due to tumour invasion and metastasis. Although histopathology and biomedical imaging techniques continue to be used as standard procedures in breast cancer diagnosis, these techniques have a number of disadvantages, including being time-consuming, the imaging in particular having attendant limited resolution, sensitivity, and specificity, leading to results that are prone to errors in human interpretation. Due to its rapidity and high specificity, Raman spectroscopy has emerged as a diagnostic tool for breast cancer, useful in identifying malignancy of breast cells, correlated with the EMT phenotype, expressed at the molecular level. Detailed biochemical information from tissue biopsies can also be provided from use of this technique. The use of Raman spectroscopy in breast cancer investigations over the past 10 years and more, including in the study of EMT, is reviewed in the present work also listing the corresponding Raman peaks reported in the literature in seeking to better facilitate identification of peaks of interest.

    M. M. Mahfuz Siraz, Debasish Roy, Md. Jafor Dewan, M. S. Alam, A. M. Jubair, Md. Bazlar Rashid, Mayeen Uddin Khandaker, D. A. Bradley, S. Yeasmin (2023)Vertical distributions of radionuclides along the tourist-attractive Marayon Tong Hill in the Bandarban district of Bangladesh, In: Environmental monitoring and assessment195(3)pp. 382-382 Springer Nature

    This is the first attempt in the world to depict the vertical distribution of radionuclides in the soil samples along several heights (900 feet, 1550 feet, and 1650 feet) of Marayon Tong hill in the Chittagong Hill Tracts, Bandarban by HPGe gamma-ray spectrometry. The average activity concentrations of Th-232, Ra-226, and K-40 were found to be 37.15 +/- 3.76 Bqkg(-1), 19.69 +/- 2.15 Bqkg(-1), and 347.82 +/- 24.50 Bqkg(-1), respectively, where in most cases, Th-232 exceeded the world average value of 30 Bqkg(-1). According to soil characterization, soils ranged from slightly acidic to moderately acidic, with low soluble salts. The radium equivalent activity, outdoor and indoor absorbed dose rate, external and internal hazard indices, external and internal effective dose rates, gamma level index, and excess lifetime cancer risk were evaluated and found to be below the recommended or world average values; but a measurable activity of Cs-137 was found at soils collected from ground level and at an altitude of 1550 feet, which possibly arises from the nuclear fallout. The evaluation of cumulative radiation doses to the inhabitants via periodic measurement is recommended due to the elevated levels of Th-232.This pioneering work in mapping the vertical distribution of naturally occurring radioactive materials (NORMs) can be an essential factual baseline data for the scientific community that may be used to evaluate the variation in NORMs in the future, especially after the commissioning of the Rooppur Nuclear Power Plant in Bangladesh in 2024.

    Siti Norbaini Sabtu, S F Abdul Sani, L M Looi, S F Chiew, Dharini Pathmanathan, D A Bradley, Z Osman (2021)Indication of high lipid content in epithelial-mesenchymal transitions of breast tissues, In: Scientific reports11(1)pp. 3250-3250

    The epithelial-mesenchymal transition (EMT) is a crucial process in cancer progression and metastasis. Study of metabolic changes during the EMT process is important in seeking to understand the biochemical changes associated with cancer progression, not least in scoping for therapeutic strategies aimed at targeting EMT. Due to the potential for high sensitivity and specificity, Raman spectroscopy was used here to study the metabolic changes associated with EMT in human breast cancer tissue. For Raman spectroscopy measurements, tissue from 23 patients were collected, comprising non-lesional, EMT and non-EMT formalin-fixed and paraffin embedded breast cancer samples. Analysis was made in the fingerprint Raman spectra region (600-1800 cm ) best associated with cancer progression biochemical changes in lipid, protein and nucleic acids. The ANOVA test followed by the Tukey's multiple comparisons test were conducted to see if there existed differences between non-lesional, EMT and non-EMT breast tissue for Raman spectroscopy measurements. Results revealed that significant differences were evident in terms of intensity between the non-lesional and EMT samples, as well as the EMT and non-EMT samples. Multivariate analysis involving independent component analysis, Principal component analysis and non-negative least square were used to analyse the Raman spectra data. The results show significant differences between EMT and non-EMT cancers in lipid, protein, and nucleic acids. This study demonstrated the capability of Raman spectroscopy supported by multivariate analysis in analysing metabolic changes in EMT breast cancer tissue.

    A. Sulieman, A. Abdelrazig, H. Al-Mohammed, M. Alkhorayef, B. Alonazi, I. I. Suliman, N. Abuhadi, D. Bradley (2020)Radiogenic risks to patients and staff from fluoro-assisted therapeutic cardiac catheterizations, In: Radiation physics and chemistry (Oxford, England : 1993)167 Elsevier

    Advances in sectional imaging have led to prolonged x-ray fluoro-assisted therapeutic cardiac catheterizations. Given the frequency of such procedures, limited data are available for patient and staff doses. For certain pediatric cardiac catheterization procedures we examine: (i) effective and organ doses, also the radiogenic and tissue reaction risks and; (ii) staff effective dose during cardiac interventions. At four cardiac catheterization centres, patient doses were measured with a calibrated kerma area product (KAP) meter; staff doses were measured using calibrated TLDs. The mean and range of age (years) and weight (kg) for patients were 4.3 (0.04-14.0) and 10.8 (3.0-46.0) respectively; the overall mean and range of fluoroscopic time (min) was 13.0 (1.4-54.8). For coronary angiography and pacemaker procedures the overall mean and range of cumulative kerma area product (CRAP, were 350 (12.0-510). The average annual staff dose of 9.0 (7.2-14.4) mSv is relatively low given the current workload. Some patients received high doses approaching the threshold for tissue reactions. Optimisation of radiation dose is required as is follow-up of patients receiving high doses to detect the possibility of tissue reactions.

    W. Elshami, M.M. Abuzaid, M.M. Gibril, A. Sulieman, D.A. Bradley (2022)Impact of high kilo-voltage peak technique on radiation dose for neonates undergoing chest radiography: Experimental study, In: Radiation physics and chemistry (Oxford, England : 1993)199 Elsevier Ltd

    Chest radiography remains the most often utilized radiological modality in the neonatal intensive care unit. Neonates are more radiosensitive and are at higher risk of cancer than adults. In addition, they have a longer life expectancy, which increases the risk of cancer. Therefore, it is essential to protect neonates from radiation hazards. The study aims to assess the effectiveness of using high HKVp technique on reducing radiation dose to neonates undergoing Antero-posterior (AP) chest x-rays. The experiment used a newborn anthropomorphic phantom to simulate a neonate. Chest x-ray images were acquired using different combinations of KVp and mAs. Dose area product (DAP) was recorded in the Digital Imaging and Communications in Medicine (DICOM) header. The effective dose was determined using Monte Carlo simulation. Subjective assessment of image quality was evaluated by three radiologists blindly. The Objective assessment of image quality uses the calculation of the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR). The reduction in the DAP and effective dose at 50 KVp was 26.7% and 19.2%, respectively and for 60 KVp it was 22.9 and 20.2, respectively. While, the reduction in the DAP and effective dose at 70 KVp was 40% and 26%, respectively. There were no significant differences in the means of the DAP, SNR, CNR, and effective dose among different combinations of KVp and mAs. The use of the high KVp technique can play an important role in reducing radiation dose without significant loss of image quality. •Use of the high KVp technique can reduce radiation dose without significant loss of image quality.•At 70 KVp, the DAP and effective dose reduced by 40% and 26%, respectively.•Use of high kVp showed no significant difference in SNR, CNR and radiation dose.•Effort should be made to reduce patients' dose without compromising diagnostic outcome.

    Abdullah Almujally, Nissren Tamam, Abdelmoneim Sulieman, Duong Thanh Tai, Hiba Omer, Nouf Abuhadi, Hassan Salah, Essam Mattar, Mayeen Uddin Khandaker, David Bradley (2022)Evaluation of paediatric computed tomography imaging for brain, and abdomen procedures, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    Computed tomography (CT) are often used for adult and pediatric patients. This is basically due to its powerful diagnostic capabilities in providing the tiniest details of pathologies in the body. Nevertheless, this detailed and accurate imaging occurs at the expense of the high doses received by the patients, although in general, the benefits outweighs the risks precisely of malignancy. Pediatrics are radiosensitive more than adults due to their longer life expectancy and their rapidly dividing cells. This study aims at measuring and evaluating pediatric patient doses in four hospitals equipped with 16, 20 and 128 CT detectors. Forty-eight pediatric patients who underwent brain (72.7%) and abdomen (36.3%) Computed Tomography are included in this study. Data includes CTDIvol (mGy) and DLP ( CTDOSE computer software which is based on Monte Carlo simulations was used to calculate the effective and organ equivalent doses (mSv). The CTDIvol (mGy) per procedure range was 11.0–95.0 mGy for brain CT and 3.0–30.0 mGy for abdomen CT. DLP on the other hand ranged between 129.0 and 2510.0 mGy cm for brain CT and 84.0–1604.0 for abdomen CT. The high doses were attributed to the fact that the protocols used for pediatric patients were the adult protocols, not bearing in mind the high radio-sensitivity of the pediatrics. Establishing a protocol for pediatric CT is hence of great importance to prevent them from receiving unnecessary high doses which may eventually cause cancer. •The radiation doses during specific pediatric CT examinations in four hospitals were evaluated.•Patient dose per CT procedure ranged from 84.0 to 2510.0 mGy cm.•Adults protocols used for pediatric patients resulted in unnecessary exposure.•Standardizing imaging protocols during pediatric CT imaging is recommended.

    Layal Jambi, Mohammed Alkhorayef, Mohammed Almuwanis, Hiba Omer, Nazar Alhasan, Duong Thanh Tai, Abdelmoneim Sulieman, David Bradley (2022)Assessment of the effective radiation dose and radiogenic effect in intravenous urography imaging procedures, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    The pathology of the urinary system is usually investigated using Intravenous Urography (IVU). The study objectives are to quantify patients’ radiation dose and radiation induced malignant tumors risk during IVU examination. The radiation doses during IVU and the subsequent risks from exposure are studied, using data from 50 patients imaged in one hospital. The demographic data given as (mean ± std) was as follows:The age of patients was 39 ± 14 years; height of patients was 1.7 ± 0.1 m, the mass was 69 ± 10 kg and the body-mass-index was 24.3 ± 4.1 kg m−2. The physical exposure parameters recorded were: kVp: 74.04 ± 3.1, mAs: 33.64 ± 4. Moreover, the average number of films per procedure was 5.72 ± 1.49. The entrance-surface air kerma (ESAK) was 2.1 ± 0.64 mGy, and the mean effective dose was 0.131 ± 0.04 mSv. Calculation of the overall cancer risk yielded 5.9 × 10−6 procedures. ESAK (mGy) and effective dose values obtained in this study were comparable with reported studies as shown in the text. The effective and cancer risk are around ten times lower during IVU procedures than for example, contrast enhanced computed tomography urography (CTU) examination. Reduction of doses received by patients to meet the values of the diagnostic reference levels without compromising the quality and clarity of the images is highly recommended. Radiation dosimetry; IVU; Radiology; Cancer risk; medical imaging. •The radiation doses during IVU and the subsequent risks from exposure are studied.•The entrance-surface air kerma (ESAK) and effective dose were quantified.•Calculation of the overall cancer risk yielded 5.85 per million procedures.•Patients received higher doses due to unoptimized imaging protocol.

    H Salah, Nissren Tamam, Mohammad Rabbaa, Mohammad Abuljoud, Ali Zailae, Alkhorayef, N Abuhadi, W Elshami, A Sulieman, D A Bradley (2023)Assessment of patients radiation doses associated with computed tomography coronary angiography, In: Applied radiation and isotopes192pp. 110548-110548

    Computed tomography coronary angiography (CTCA) has generated tremendous interest over the past 20 years by using multidetector computed tomography (MDCT) because of its high diagnostic accuracy and efficacy in assessing patients with coronary artery disease. This technique is related to high radiation doses, which has raised serious concerns in the literature. Effective dose (E, mSv) may be a single parameter meant to reflect the relative risk from radiation exposure. Therefore, it is necessary to calculate this quantity to point to relative radiation risk. The objectives of this study are to evaluate patients' exposure during diagnostic CCTA procedures and to estimate the risks. Seven hundred ninety patients were estimated during three successive years. The patient's exposure was estimated based on a CT device's delivered radiation dose (Siemens Somatom Sensation 64 (64-MDCT)). The participating physicians obtained the parameters relevant to the radiation dose from the scan protocol generated by the CT system after each CCTA study. The parameters included the volume CT dose index (CTDIvol, mGy) and dose length product (DLP, mGy × cm). The mean and range of CTDIvol (mGy) and DLP (mGy × cm) for three respective year was (2018):10.8 (1.14-77.7) and 2369.8 ± 1231.4 (290.4-6188.9), (2019): 13.82 (1.13-348.5), and 2180.5 (501.8-9534.5) and (2020) 10.9 (0.7-52.9) and 1877.3 (149.4-5011.1), respectively. Patients' effective doses were higher compared to previous studies. Therefore, the CT acquisition parameter optimization is vital to reduce the dose to its minimal value.

    Rasha Jaafar, Abdelmoneim Sulieman, Nissren Tamam, Hiba Omer, Abdelrahman Elnour, Ali Alhailiy, Mohammed Alkhorayef, Mayeen Uddin Khandaker, D.A. Bradley (2021)Multiphase vascular lower limb computed tomography: Assessment of patients doses and radiogenic risk, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier Ltd

    The purposes of this study are to estimate patient's radiation doses and radiogenic risk in vascular lower limb computed tomography (CT). In total, 188 (109 (68%) males and 79 (42%) females) patients undergone vascular CT for the lower limbs at three radiology departments. Three CT scanners, 160, 128, and 64 slices CT, were used in this study. CT-Expo and ImPACT CT dose estimation software were used to extrapolate the effective dose. The overall average and range of volume CT dose index (CTDIvol (mGy) and dose length product (DLP) ( 7.3 (2.3–22.9), and 3000 (279.1–8374.4) the same order. The overall effective dose average value was 18 mSv per procedure. The proposed diagnostic reference level (DRL) values are 9 mGy (CTDIvol) and 2500 mGy cm (DLP) per vascular lower limb CT procedure. The risk of cancer from the peripheral CT angiography procedures ranges from 1 in 1000 to 1 in 3000 procedures. The cancer risk per procedure should be considered during the justification and image acquisition stages. •Peripheral CT angiography for lower extremities were performed using three CT machines.•CT dose per procedure (DLP ( is higher up to 10 times compared to previous.•Patients are being seen to be receiving unnecessary radiation doses during triphasic CT abdomen procedure.•A local diagnostic reference level was proposed was established for further dose reduction.

    Yarima Mudassir Hassan, Hasnah Muhd Zaid, Beh Hoe Guan, Mayeen Uddin Khandaker, D. A. Bradley, A. Sulieman, Sk A. Latif (2021)Radioactivity in staple foodstuffs and concomitant dose to the population of Jigawa state, Nigeria, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier

    In addition to the presence of primordial radionuclides, inputs from technological progress together with nuclear technology proliferation have also contributed to the level of radioactivity in the soil. Due to the transfer of radionuclides in the chain soil-plant-human, notably via the ingestion pathway, it is important to assess the concentrations of radioactive materials in staple foodstuffs. Present study via HPGe gamma-ray spectrometry was undertaken to measure the concentrations of Ra-226, Ra-228 and K-40 in the more prominent staple Nigerian foodstuffs (rice, wheat, and millet). For Ra-226, Ra-228 and K-40, the activity concentrations (Bq/kg) in rice were in the respective range of 0.9-2.4, 0.5-2.4 and 78-326, while for wheat they were 1.3-5.1, 0.7-1.2 and 192-264, and for millet the range of 2.5-9.9, 0.8-1.9 and 186-197 in the same order. Overall, the measured data were found to be below the global average values of 67 Bq/kg, 82 Bq/kg and 310 Bq/kg prescribed by UNSCEAR for Ra-226 Ra-228 and K-40, respectively. The committed effective dose via consumption of the studied foodstuffs shows millet to have the greatest contribution, albeit not superseding the dose limit of 290 mu Sv/y proposed by UNSCEAR. The threshold consumption rates for the studied foodstuffs were within the range of 66-343 kg/y (mean value 153 kg/y), approximating to individual consumption of similar to 419 g/d, not equating to unacceptable radiological risk. The lifetime cancer risk from consumption of the studied food was also assessed and found to be below the ICRP (2013) cancer risk factor of 4.5 x 10(-3) based on an additional annual dose limit of 1 mSv (above background) for the general public. In summary, consumption of the studied foodstuffs poses an insubstantial threat to the public.

    K.S. Almugren, S.F. Abdul Sani, M.S. Jaafar, Azhar Mohamad, A.S Siti Shafiqah, D.A. Bradley (2023)The effect of acute gamma radiation onto growth media for mother culture of a Volvariella mushroom, In: Radiation physics and chemistry (Oxford, England : 1993)202 Elsevier Ltd

    Potato Dextrose Agar (PDA) is a semicrystalline polymer made from amylopectin, agarose, and amylose, used in laboratories for Agar plate culturing for a multitude of fungal strains. The existing pretreatment method for the elimination of pathogenic bacteria, namely steam sterilization, has shown several drawbacks, including high cost, uneven heating due to temperature differentials and an inability to treat specimens volumetrically. These drawbacks are mitigated by gamma irradiation, being carried out in order to improve hygienic quality and germination control, retarding sprouting, also enhancing physical attributes of the food product. Present study investigates the growth and survival of pretreated potato dextrose agar (PDA) substrate with gamma irradiations, for doses ranging from 0 kGy (unirradiated) up to 20 kGy, particularly for Volvariella mushroom cultivation. The relative elemental composition of PDA substrate has been obtained through use of Energy Dispersive X-ray Analysis (EDX), identifying carbohydrate (53.35%), oxygen (45.29%) and 1.36% of mineral trace elements. Gamma irradiation doses to the PDA substrate of 0.5 kGy, 1 kGy and 1.5 kGy have been found to be associated with respective growth rates of 0.93 ± 0.03, 0.94 ± 0.02 and 0.89 ± 0.02 cm/day, the PDA becoming more amorphous and acidic with reduced viscosity at higher doses. The findings of this study could pave the way for a low-cost yet highly effective system for irradiation in mushroom, as well as offering a viable alternative to current conventional sterilizations, well suited to applications in food security. •Potato dextrose agar (PDA) substrate irradiated with gamma at 0.5–20 kGy.•PDA substrate used for Volvariella mushroom cultivation.•PDA substrate becoming amorphous and acidic with reduced viscosity at higher doses.•PDA substrate of 1 kGy have been found to produce effective growth rates.•Gamma irradiation shows an alternative and effective method of sterilization.

    A. A. Z. Ahmad Nazeri, S. F. Abdul Sani, N. M. Ung, K. S. Almugren, F. H. Alkallas, D. A. Bradley (2021)Borosilicate glass 60Co high dose rate brachytherapy thermoluminescence dosimetry, In: Applied radiation and isotopes176 Elsevier

    Brachytherapy is commonly used in treatment of cervical, prostate, breast and skin cancers, also for oral cancers, typically via the application of sealed radioactive sources that are inserted within or alongside the area to be treated. A particular aim of the various brachytherapy techniques is to accurately transfer to the targeted tumour the largest possible dose, at the same time minimizing dose to the surrounding normal tissue, including organs at risk. The dose fall-off with distance from the sources is steep, the dose gradient representing a prime factor in determining the dose distribution, also representing a challenge to the conduct of measurements around sources. Amorphous borosilicate glass (B2O3) in the form of microscope cover slips is recognized to offer a practicable system for such thermoluminescence dosimetry (TLD), providing for high-spatial resolution (down to < 1 mm), wide dynamic dose range, good reproducibility and reusability, minimal fading, resistance to water and low cost. Herein, investigation is made of the proposed dosimeter using a 1.25 MeV High Dose Rate (HDR) Co-60 brachytherapy source, characterizing dose response, sensitivity, linearity index and fading. Analysis of the TL glow curves were obtained using the T-max -T-stop method and first-order kinetics using GlowFit software, detailing the frequency factors and activation energy.

    A. Sulieman, N. Tamam, Abdelrahman Elnour, M. Alkhorayef, E. Babikir, Huda I. Al-Mohammed, N. Abuhadi, Mayeen Uddin Khandaker, David A. Bradley (2022)Effective radiation dose and radiogenic cancer risk during contrast enhanced abdominal computed tomography examinations, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    Pediatrics and children have higher radiosensitivity to ionizing radiation and radiogenic risks than adults due to their rapidly dividing tissues. This study explores the infant and children radiation doses during computed tomography (CT) abdomen and estimates the cancer risk from the procedure. In total, 87 were examined for CT enhanced abdominal examination. The abdominal CT scan with contrast was performed using a 128-slice multi slice CT (MSCT) scan. The mean, standard deviation, and range of patients' age (years) are 13 ± 4.5 (2–17). The mean and range of the air kerma length product (PKL( and volume CT air kerma index (Cvol (mGy)) were 1740 (157.8–8440.3) ( and 9.8 (2.09–45.77) (mGy) per CT abdomen procedure, respectively. The mean and range of the effective dose (mSv) per procedure are 34 (3.14–176.8). The average radiogenic risk per CT procedure is one cancer incidence per 250 CT enhanced abdomen procedures. The mean and range of total irradiation even are 4.0 (2.0–8.0) times per procedure. The results of this study showed that child risk is high compared to other CT examinations. Therefore, patients’ dose optimization and proper establishment of a diagnostic reference level (DRL) are necessary to preventing avoidable radiation risks. •Radiation dose were assessed for 87 abdomen Contrast enhanced Computed tomography (CECT) examinations.•The average radiogenic risk per CT procedure is one cancer incidence per 250 CT enhanced abdomen procedures.•The results of this study showed that child risk is high compared to other CT examinations.•The results obtained in this study are similar to those reported in previous studies.

    Ming Tsuey Chew, Eman Daar, Mayeen Uddin Khandaker, Bleddyn Jones, Andrew Nisbet, David A Bradley (2021)Low radiation dose to treat pneumonia and other inflammations, In: British journal of radiology94(1124)pp. 20201265-20201265

    Infection, the invasion of pathogenic microorganisms and viruses, causes reactive inflammation mediated by endogenous signals, with influx of leucocytes with distinct properties and capable of mounting a cellular or antibody response. Different forms of inflammation may also occur in response to tumours, in allergy and autoimmune disorders. Pneumonia, respiratory tract infection and septic shock for instance can arise as serious complications of the Covid-19 virus. While radiotherapy has been most widely used to control malignant tumours, it has also been used for treatment of non-malignant diseases, including acute and chronic inflammation in situations where anti-inflammatory drugs may be ineffective or contraindicated. The present review examines the history and prospects for low-dose anti-inflammatory radiation treatments, the present interest largely being motivated by the increased incidence of pulmonary disease associated Covid-19 infections. Evidence in support of the suggested efficacy are covered, together with an appraisal of one of the number of potential convenient sources that could complement external beam arrangements.

    Meshari Alnaaimi, Abdelmoneim Sulieman, Mohammed Alkhorayef, Hasan Salah, Musa Alduaij, Mosab Algaily, O. Alomair, Y. Alashban, H. Almohammad, David Bradley, C. Kappas (2021)Organs dosimetry in targeted radionuclide therapy, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier

    The objective of this study is to assess the patients' effective and organ dose during theranostic applications in Kuwait. In total, eighteen adults' patients were conducted nuclear medicine procedures with 177Lu Dotatate for theranostic purpose in Kuwait Cancer control center (KCCC), Kuwait. Medium energy collimator (MEC) (208 keV Scatter 26% better than 113 keV Scatter 60%) was utilized to obtain scans in definite time intervals ranged from one to 2 h (before voiding), 6:00, 24:00, 48:00, 72:00 h. Patients, tissue and organ radiation doses were computed utilizing OLINDA/EXM Software. The average radiation effective dose (in mSv/MBq) for bladder, liver, and both kidneys (left & right), were 0.36, 0.08, 0.61 & 0.60. The range of the effective dose was from 0.55 mSv to 7.7 mSv. The acquired scans using 177Lu were delivered diagnostic findings. The patients' effective dose is lower compared to the previous studies. Variation is attributed to the departmental protocol and administered activity. The values of the mean organ dose were comparable and lower than previously published studies. Different organs have different level of doses, which may affected by the presence of the metastatic tumors in the entire organ.

    Mayeen Uddin Khandaker, Nwokoma Oliver Chijioke, Nurul' Adillah Binti Heffny, David A. Bradley, Abdullah Alsubaie, Abdelmoneim Sulieman, Mohammad Rashed Faruque, M. Sayyed, K. S. Al-mugren (2021)Elevated concentrations of metal(Loids) in seaweed and the concomitant exposure to humans, In: Foods10(2) Mdpi

    While the consumption of seaweed and seaweed-based products is very common amongst East Asian nations, forming a notable component of the daily diet, relatively very few studies have concerned the concentrations of heavy metals in these together with potential effects on human health. The present study analyses the concentrations of 17 elements in locally resourced seaweed, also assessing potential noncarcinogenic and carcinogenic risks. The samples were ground, homogenized, and quantified using the ICP-OES technique. It has been found that the essential elements K, Ca, Mg, Zn, and Na typically show concentrations somewhat greater than a number of potentially toxic metals, in particular, Cd, Pb, Ag, and As, with exceptions being Ni, Cr-VI, and Si. Statistical analysis indicates all of the latter to have similar origin, with increased concentration of these metals within the marine ecosystem. While the daily estimated intake of most metals is seen to be within the daily dietary allowance level recommended by various international organizations, the noncarcinogenic risk shows a value greater than unity, estimated via the hazard quotient. This indicates a potential for adverse effects to health arising from consumption of the sampled seaweed. The carcinogenic risk resulting from nonessential elements shows values greater than the United States Environmental Protection Agency (US-EPA) reference limit of 10(-4). Considering the nonbiodegradability of heavy metals and metalloids and their potential accumulation in seaweed, there is need for critical examination of metal levels in the seaweeds obtained from the present study locations, together with the introduction of practices of removal of heavy metals via bio-adsorbent techniques.

    Matthew Tikpangi Kolo, Mayeen Uddin Khandaker, Matthew O. Isinkaye, Anayo Ugwuanyi, Nwachukwu Chibueze, Opeyemi Falade, Paul Onuche, Amal Alqahtani, D.A. Bradley, I.M. Ashraf (2023)Radon in groundwater sources of Bosso Community in North Central Nigeria and concomitant doses to the public, In: Radiation physics and chemistry (Oxford, England : 1993)203
    M. Kanmalar, Siti Fairus Abdul Sani, Nur Izzahtul Nabilla B. Kamri, Nur Akmarina B. M. Said, Amirah Hajirah B. A. Jamil, S. Kuppusamy, K. S. Mun, D. A. Bradley (2022)Raman spectroscopy biochemical characterisation of bladder cancer cisplatin resistance regulated by FDFT1: a review, In: Cellular & molecular biology letters27(1)pp. 9-9 BioMed Central

    Bladder cancer is the fourth most common malignancy in males. It can present across the whole continuum of severity, from mild through well-differentiated disease to extremely malignant tumours with poor survival rates. As with other vital organ malignancies, proper clinical management involves accurate diagnosis and staging. Chemotherapy consisting of a cisplatin-based regimen is the mainstay in the management of muscle-invasive bladder cancers. Control via cisplatin-based chemotherapy is threatened by the development of chemoresistance. Intracellular cholesterol biosynthesis in bladder cancer cells is considered a contributory factor in determining the chemotherapy response. Farnesyl-diphosphate farnesyltransferase 1 (FDFT1), one of the main regulatory components in cholesterol biosynthesis, may play a role in determining sensitivity towards chemotherapy compounds in bladder cancer. FDFT1-associated molecular identification might serve as an alternative or appendage strategy for early prediction of potentially chemoresistant muscle-invasive bladder cancer tissues. This can be accomplished using Raman spectroscopy. Developments in the instrumentation have led to it becoming one of the most convenient forms of analysis, and there is a highly realistic chance that it will become an effective tool in the pathology lab. Chemosensitive bladder cancer tissues tend to have a higher lipid content, more protein genes and more cholesterol metabolites. These are believed to be associated with resistance towards bladder cancer chemotherapy. Herein, Raman peak assignments have been tabulated as an aid to indicating metabolic changes in bladder cancer tissues that are potentially correlated with FDFT1 expression.

    Wadah M. Ali, Abdelmoneim Sulieman, Hassan Salah, H. I. Almohammed, Mohammed Alkhorayef, D. A. Bradley (2021)Short-term retention of 99mTc activity in bone scintigraphy, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier

    The objective of present study is estimation of the radioactivity held within the urinary bladder and kidneys 3 h post radiopharmaceutical (Tc-99m-MDP) administration, comparison being made via use of MIRDose. Using the conjugate-view method and built-in camera software Mediso XP Interview, urinary bladder and kidney radionuclide activities were calculated using patient clinical data acquired at the aforesaid 3 h post Tc-99m-MDP injection juncture. The study was of a cohort of 40 patients attending for staging and cancer follow-up at the Nuclear Medicine Department, Royal Care International Hospital (RCIH), Sudan, Ethical and Research Committee approval for the study having been obtained. The radioisotope biokinetics were simulated using the Medical Internal Radiation Dose (MIRD) biokinetics model, specifically in regard to radionuclide activity in the kidneys and bladder. The results were compared with the data achieved via clinical study, showing the experimentally estimated radionuclide activity in the kidney to be greater by some 50% compared to that of simulation while the bladder radionuclide activity was found to be just 2% of the simulation result. The study also found that 0.9% of the administered radioactivity remained in the urinary bladder and kidneys 3 h post administration of the radionuclide, suggestive of low radiation dose to the urinary bladder and kidneys post Tc-99m-MDP bone scans.

    Mohammed Alsufayan, Abdelmoneim Sulieman, Rayan Moslem, Abdullah Asiri, Abdullah Alomary, Bandar M. Alanazi, Hassan Aldossari, Batil Alonazi, David A. Bradley (2021)Assessment of imaging protocol and patients radiation exposure in computed tomography colonography, In: Applied sciences11(11) Mdpi

    In the screening and identifying of colon and rectum malignancy, computed tomography colonography (CTC) is a highly effective imaging technique, albeit patients receiving a significant effective dose. Accordingly, patient dose evaluation is an important need, seeking to ensure benefits outweigh the projected cancer risk. Objective: For CTC procedures carried out in the Radiology Department, Medical Imaging Operation Services, King Fahad Medical City (KFMC), evaluation is done using the current American College of Radiology (ACR) imaging protocol and concomitant patient-effective doses. Study is carried out on a sample size of 55 CTC procedures, involving 25 males (45%) and 30 females (55%). The patients were classified as follows: two groups based on CT machine; four groups based on the applied protocol; and three groups based on the procedure results. All procedures were carried out using two machines, the products of two different vendors (a GE Healthcare DISCOVERY CT 750 HD 64 slices dual-energy scanner and a Philips Brilliance CT 64 slices scanner). The overall mean, standard deviation (SD), median, and range of the effective dose (in mSv) were 11.57 +/- 7.75, 9.25 (2.17-31.93). Automatic tube current modulation (ATCM) shows a significant increase in CTDIvol up to 69% and effective dose (mSv) up to 95% than the manual tube current (mA) compared to the standard protocol. The CT protocol variation results in a three-fold variation in patient-effective dose. The technologist role is crucial in selecting a noise reference based on patient weight and adjusting tube current per slice to avoid overexposure during ATCM protocol.

    Ali Aamry, Abdelmoneim Sulieman, N. Tamam, Nouf H. Abuhadi, Yehia Johary, Hussin Aamri, E. Mattar, Hassan Salah, Hamid Osman, Mayeen Uddin Khandaker, David Bradley (2022)Evaluation of the annual occupational effective doses in a SPECT/CT department, In: Applied radiation and isotopes181pp. 110097-110097 Elsevier Ltd

    Staff occupational radiation exposure is limited to 20 mSv annually to preclude tissue reaction and lower risk of cancer effect. Staff occupational exposure arises during the preparation, injection, and scanning of the patients. Recent studies reported that nuclear medicine personnel might exceed the annual dose limit in high workload and poor radiation protection circumstances. Therefore, an accurate estimation of the annual dose limit is recommended. The goal of this research is to calculate the cumulative external effective dose (mSv) per year for nuclear medicine physicians, technologists, and nurses at SPECT/CT department. A total of 15 staff worked in the nuclear medicine department at King Saud Medical City (KSMC), Riyadh, Saudi Arabia were evaluated for the last six years. 99mTc is used more frequently for most of the patients. The procedures include renal, cardiac scintigraphy procedures. Staff dose was quantified using calibrated thermoluminecnt dosimeters (TLD-100) with an automatic TLD reader (Harshaw 6600). Exposure to ionizing radiation was evaluated in terms of deep doses (Hp(10) were evaluated. The overall average and standard deviation of the external doses for nuclear medicine physicians, technologists' and nurses were 1.8 ± 0.7, 1.9 ± 0.6, 2.0 ± 0.9, 2.2 ± 0.8, 6.0 ± 2.8, and 3.6 ± 1.3 for the years 2015,2016,2017,2018,2019, and 2020, respectively. Technologists and nurses received higher doses of compared to the nuclear medicine physicians. Technologists and nurses involved in radionuclide preparation, patients' injection, and image acquisition. Staff annual exposure is below the annual dose limits; however, this external dose is considered high compared to the current workload. •Staff annual effective dose was estimated at nuclear medicine department equipped with two SPECT/CT systems.•External effective dose in terms of Hp(10) was monitored for six consecutive years.•Occupational exposure was quantified with thermoluminecnt dosimeters (TLD-100).•Technologists and nurses received higher doses than the nuclear medicine physicians.•Staff annual radiation from external exposure is 50% below the annual dose limits.

    Noor Zati Hani Abu Hanifah, Suhairul Hashim, Halmat Jalal Hassan, Nur Nabihah Yusof, D.A. Bradley (2021)Radioactive material in cosmetic and healthcare products: Regulatory controls, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier Ltd

    We provide an overview of the issue of the regulatory control of cosmetics and healthcare products that intentionally contain added radioactivity, the suggested health benefits from such product utilisation being firmly within the realm of the unproven. Examples are offered of control practices in several countries. Access to the products depends strongly on national controls. This apart, there is a general lacking in public awareness of such radioactive content and the potential for harm in the circumstance of daily exposure to such media. With prolonged use of these adding to cancer risk, at the manufacturing stage it is suggested that the products should be subject to regulatory inspection and certification, crucial in reducing radiation exposure. In particular, based on published data from a number of European and Asian countries, review is made of such cosmetic and healthcare products, also including estimates of the effective doses implied from the utilisation of these. The information concerns the progeny of the primordial radionuclides 238U, 232Th, and 40K, encompassing a comparatively large range of values, from 1.7×10-4 to 2.8×103 Bq per kg for 238U, 3×10-5 to 1.2×104 Bq per kg for 232Th and 1.1×10-3 to 9.5×102 for 40K. In many countries standards and regulations have been implemented typically with authority over exemptions for radioactive materials in cosmetic and healthcare products. In the absence of harmonised regulations, transnational access and the use of such cosmetic and healthcare products will remain a worldwide concern. •The exemption limits of various national authorities have been reviewed.•The effective dose from use of selected cosmetic and healthcare products assessed.•Call made for global harmonisation in regulation of NORM-added consumer products.

    Nissren Tamam, H. Salah, Mohammad Rabbaa, Mohammad Abuljoud, A. Sulieman, M. Alkhorayef, D. A. Bradley (2021)Evaluation of patients radiation dose during mammography imaging procedure, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier

    This study investigates patients' dose levels during digital mammography procedures and proposes a local diagnostic reference level (DRL). The patient sample is 1055 patients who have been examined at the Riyadh Care Hospital, Riyadh, Saudi Arabia. All procedures were carried out for medically justified clinical conditions. All procedures were carried out using a direct digital mammography (DDR) radiology system. The mean and range of ESAK (mGy) were 5.19 +/- 3.18 (0.33-29.9), while the mean AGD (mGy) is 1.3 +/-(1.0-7.2) per procedure. The third quartile value for ESAK (mGy) and AGD (mGy) is 6 and 1.5, respectively. Measured ESAK (mGy) per procedure and estimated AGD are comparable with previous studies. The interpatient and interdepartmental variation is attributed mainly to the number of projections per procedure.

    S. Karthikayini, Mefleh S. Hamideen, A. Chandrasekaran, Mayeen Uddin Khandaker, D.A. Bradley (2023)X-ray fluorescence analysis of coastal sediments of Tamil Nadu with a statistical approach, In: Radiation physics and chemistry (Oxford, England : 1993)209 Elsevier Ltd

    X-ray fluorescence spectroscopy is applied to determine the concentration of essential and toxic heavy metals such as silicon (Si), potassium (K), calcium (Ca), titanium (Ti), iron (Fe), copper (Cu), zinc (Zn), nickel (Ni), and lead (Pb) in the sediments of Kovalam coastal area, Tamil Nadu, India. Fe (599280 ppm), an essential heavy metal/mineral shows the highest average concentration, followed by Si (181593 ppm), Ca (130913 ppm), K (99673 ppm), Ti (77620 ppm), Cu (64 ppm), Ni (43 ppm), Pb (20 ppm), and Zn (8 ppm). Heavy metal contamination was assessed using various pollution indicators such as the geo-accumulation index (Igeo), contamination factor (CF), pollution load index (PLI), and enrichment factor (EF). Si, K, Ca, Ti, Fe, Cu, Ni, Pb, and Zn had mean Igeo values of −1.29, 1.54, 1.07, 3.59, 3.19, 0.64, −1.14, −0.22, and −3.70, respectively. Except for Ti (19.36) and Fe (13.87), the average CF value for determined heavy metals was significantly low. The PLI value ranges from 1.47 to 2.46. Heavy metal EF values are greater than 1 in all sampling locations. Multivariate statistical analyses such as Pearson correlation analysis, cluster analysis, and principal component analysis are performed to identify the sources of heavy metals in the studied sediment samples. The findings indicate that anthropogenic sources such as boating and tourism activities have a probable contribution on the enrichment of K, Ca, Ti, Fe, Cu, and Pb in sediments, necessitating more attention in monitoring of toxic heavy metals (such as Pb) contamination in the coastal environment. •Concentration of Fe, Si, Ca, K, Ti, Cu, Ni, Pb, Zn was reported for sediments by XRF.•Ti, Fe and K is found to be 19, 13 and 4 times more than the background value.•Statistical methods are applied to identify the metal sources.•Ti, Fe, Ca, Cu and K are derived from anthropogenic activities.

    Abdullah Alsubaie, Eman Daar, L. Alsulaiti, Abdullah N. Al-Dabbous, Mariem Chamakh, Maisarah Jaafar, D A Bradley (2020)Reprint of “Elemental evaluation of urban road dirt in tropical, arid and maritime climates”, In: Radiation physics and chemistry (Oxford, England : 1993)167 Elsevier Ltd

    Interest is in vehicular trace elemental contributions to the environment, evaluated via analysis of road dirt. Results from SEM/EDX, ICP-MS and ICP-OES are compared for a wide range of elements. ICP-OES and ICPMS provide absolute quantification while SEM/EDX has provided weight % assessments. Roadside dirt has been sampled along busy campus roads of universities/research centres in Guildford, Riyadh, Kuwait City, Doha and Kuala Lumpur, satisfying interest in climatic influences as well as vehicle engine size (Gulf non-commercial vehicle engine capacities tending to be greater than those in the UK or Malaysia). A total of 100 street dust samples have been analyzed, elemental concentrations being reported for Mg, Al, Ti, Mn, Fe, Co, Zr, Mo, Ba, Tl, V, Rd, Pb, Cu, Zn, Ni, Cr, Cd, As, Hg and Au. For all five urban centres, Al, Fe, Mg, and Si values were found to be well above background while concentrations of Ti, Cr and Ba were lower than values reported by others. Au and Ag from catalytic convertors were found in some centres, albeit at very low concentrations and with particle sizes of the order of 0.5 µm. The various techniques offer complementary information on vehicular emission elemental concentrations in urban environments. •Metal element concentrations investigated in road dirt.•Concentration obtained in urban road dirt in tropical, arid and maritime climates.•Elevated levels Al, Fe, Mg and Si found, less so in tropical and maritime roads than in the arid zones.•The concentrations of Mg show greater elevations in a few of the Doha locations.

    Duong Thanh Tai, Truong Thi Hong Loan, Abdelmoneim Sulieman, Nissren Tamam, Hiba Omer, David A. Bradley (2021)Measurement of neutron dose equivalent within and outside of a linac treatment vault using a neutron survey meter, In: Quantum beam science5(4) Mdpi

    This work concerns neutron doses associated with the use of a Siemens Primus M5497 electron accelerator, which is operated in the photon mode at 15 MV. The conditions offer a situation within which a fraction of the bremsstrahlung emission energies exceed the photoneutron threshold. For different field sizes, an investigation has been made of neutron dose equivalent values at various measurement locations, including: (i) At the treatment table, at a source-surface distance of 100 cm; (ii) at the level of the floor directly adjacent to the treatment table; and (iii) in the control room and patient waiting area. The evaluated neutron dose equivalent was found to range from 0.0001 to 8.6 mSv/h, notably with the greatest value at the level of the floor directly adjacent to the treatment couch (8.6 mSv/h) exceeding the greatest value on the treatment table (5.5 mSv/h). Low values ranging from unobservable to between 0.0001 to 0.0002 mSv/h neutron dose were recorded around the control room and patient waiting area. For measurements on the floor, the study showed the dose equivalent to be greatest with the jaws closed. These data, most particularly concerning neutron distribution within the treatment room, are of great importance in making steps towards improving patient safety via the provision of protective measures.

    S. F. Abdul Sani, M. K. Muhamad Azim, A. A. Marzuki, M. U. Khandaker, K. S. Almugren, E. Daar, F. H. Alkallas, D. A. Bradley (2022)Radioactivity and elemental concentrations of natural and commercial salt, In: Radiation physics and chemistry (Oxford, England : 1993)190 Elsevier

    Salt (NaCl) has importance not only in regard to the seasoning and preservation of food but also in greater mass utilisation settings, including the salting of roads in wintery conditions. The assessment of health benefits and risk from the intake of salt is of paramount importance, well appreciated in regard to hypernatremia and hypertension but much less considered within the content of natural radioactivity and heavy metals contamination. Present study examines the elemental and radionuclide concentrations of commonly used artificial salts in Malaysia, including Himalayan salt, table salt and Dead Sea cooking salt along with the natural Jordan Dead Sea salt, employing the techniques of Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and High Purity Germanium (HPGe) gamma-ray spectrometry. Measured data have been compared with international advisory limits, as provided by the World Health Organization (WHO) and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Individual health risk assessment has been couched in terms of committed effective dose per year from the radionuclides U-238, Th-232, K-40, resulting from the consumption of the various salt inputs. This has led to an upper estimate for terrestrial radionuclide exposure radiation dose to individuals of some 17.1 mu Svy(-1), with an average of 4.3 mu Svy(-1), the latter some 70 times lower compared to the UNSCEAR reference annual advisory dose limit of 290 mu Sv (corresponding to the typical allowable limit for public exposures of 1 mSvy(-1)), representing negligible risk. With respect to heavy metals, the estimated daily intake (EDI) due to the consumption of salts shows the investigated salt samples to all be within the tolerable daily intake (TDI) as guided by the WHO, thereby posing inappreciable toxicity to human health.

    H. S Poh, M. C Lee, S. S Yap, S. Y Teow, D. A Bradley, S. L Yap (2020)Potential use of plasma focus radiation sources in superficial cancer therapy, In: Japanese Journal of Applied Physics59(SH) IOP Publishing

    The new multidisciplinary field of plasma medicine combines plasma physics, electrical engineering, life sciences and clinical medicine. Bekeschus et al. [Plasma Processes Polym. 16, 1800033 (2019)]. Here we explore potential uses in medicine, most particularly cancer therapy, the plasma source being brought out of the field of industrial applications into the life sciences, the focus being on superficial cancer radiotherapy strategies. Existing radiotherapy practices for such cancers rely on the use of rather large facilities, most popularly the electron linear accelerator and X-ray tube-based devices. Conversely, a compact plasma radiation source can be housed in a relatively small space, there being considerable promise for such devices to produce the fluence requirements of radiotherapy for treatment of skin cancers. The present study of feasibility investigates the plasma focus device, with the emission produced by a single discharge shown to generate an X-ray dose of few tens of mGy. The X-ray dose is the integration of emission in the discharge durations of less than a s, it is therefore possible using these devices to build up fractional irradiation dose through repetitive operation of the discharge system.

    M.J. Abedin, M.R. Karim, Mayeen Uddin Khandaker, M. Kamal, S. Hossain, M.H.A. Miah, D.A. Bradley, M.R.I. Faruque, M.I. Sayyed (2020)Dispersion of radionuclides from coal-fired brick kilns and concomitant impact on human health and the environment, In: Radiation physics and chemistry (Oxford, England : 1993)177 Elsevier Ltd

    Realizing the probable health implications via the exposures to radionuclides released from coal-fired brick kilns, concentrations of terrestrial radionuclides in feed coal, fly- and bottom ash collected from some major coal-fired brick kilns of Southern region in Bangladesh were measured using HPGe γ-ray spectrometry. Respective mean activity concentrations (Bq kg−1) for 226Ra, 232Th and 40K were found to be 36.3 ± 1.8, 26.2 ± 2.1 and 314 ± 18 in feed coal; 60.8 ± 3.9, 36.6 ± 3.9 and 338 ± 19 in fly ash; 54.9 ± 4.0, 39.7 ± 4.6 and 311 ± 18.0 in bottom ash samples. As a result of the combustion process, radionuclide concentration enhancements have been observed in proceeding from feed coal to fly- and bottom-ash. The calculated values of air absorbed dose-rates for fly- and bottom-ash are greater than the world average of 55 nGy/h reported by UNSCEAR, and the Lifetime Cancer Risk (LCR) approaches towards the safe limit recommended by the ICRP. As such, this does flag up a potential concern for those dwelling in nearby areas, especially for the coal workers who normally do not take any protective measures against exposure to ash dust. Multivariate statistical analysis has been used in examining for correlations between the origins of the radionuclides and their influence on the calculated radiological parameters. The measured data indicate significance for human health, also for the scientific community, and could be used for modeling studies in the region. •Coal fired brick kilns release terrestrial radionuclides via inhalable ash particles.•Prolonged inhalation of smoke/ash gives rise enhanced radiation exposure to lungs.•Hazardous level of absorbed dose and carcinogenic risk were found for exposed population•Respiratory protection of kiln workers and members of public is highly recommended for radioprotection reasons.•This study suggests the discharging management of fly ash should be revised significantly.

    Abdullah Almujally, Saad Alenezi, Khalid Nasser Alddosary, Ahmed Otayni, Abdelmoneim Sulieman, Amr Abdelghani, Nissren Tamam, Raafat Mohtasib, Ahmed Masawi, Belal Moftah, D.A. Bradley (2023)Abdomen and pelvis computed tomography procedure: Effective dose assessment and establishment of a local diagnostic reference level, In: Radiation physics and chemistry (Oxford, England : 1993)203 Elsevier Ltd

    Exposure to ionizing radiation may induce cancer risk to the patients proportional to the radiation absorbed dose and the organ sensitivity. Therefore protection of radiation exposure is essential to minimize the radiation cancer risk and prevent the deterministic effects. The International Atomic Energy Agency (IAEA) encourages member countries to establish national diagnostic reference levels (DRLs) to reduce unjustified radiation exposure. This study establishes a local DRL for computed tomography (CT) abdomen and pelvis procedures. In total, 1444 CT abdomen procedures were carried out during nine months. CT abdomen procedures were carried out at King Faisal Specialist Hospital and research center using six CT machines from different vendors. The mean and range of patients' weight (kg) are 50 (42–120). The recommended DRLs values in DLP ( and CTDIvol (mGy) were 900 and 15 per CT abdomen and pelvis procedure, respectively. 3% (41 cases) were higher than the national DRL for CT abdomen and pelvis. The proposed DRL values are slightly higher than the European and the American College of Radiologists (ACR) DRL values in DLP. The purpose of DRL in terms of CTDIvol (mGy) is comparable with the international guidelines. Thus reducing the scan length, is recommended ensuring that patients receive a minimal possible radiation dose while maintaining the image quality. •Patient radiation was calculated for CT abdomen examinations.•Six multi-detector CT machines 64, 128, 384 and 256 (three machines) were used.•3% (41 cases) were higher than the national DRL for CT abdomen and pelvis.•The proposed DRL is higher than previously reported values in Europe.

    Amir Entezam, Andrew Fielding, David Bradley, Davide Fontanarosa (2023)Absorbed dose calculation for a realistic CT-derived mouse phantom irradiated with a standard Cs-137 cell irradiator using a Monte Carlo method, In: PloS one18(2)pp. e0280765-e0280765 Public Library Science

    Computed tomography (CT) derived Monte Carlo (MC) phantoms allow dose determination within small animal models that is not feasible with in-vivo dosimetry. The aim of this study was to develop a CT-derived MC phantom generated from a mouse with a xenograft tumour that could then be used to calculate both the dose heterogeneity in the tumour volume and out of field scattered dose for pre-clinical small animal irradiation experiments. A BEAMnrc Monte-Carlo model has been built of our irradiation system that comprises a lead collimator with a 1 cm diameter aperture fitted to a Cs-137 gamma irradiator. The MC model of the irradiation system was validated by comparing the calculated dose results with dosimetric film measurement in a polymethyl methacrylate (PMMA) phantom using a 1D gamma-index analysis. Dose distributions in the MC mouse phantom were calculated and visualized on the CT-image data. Dose volume histograms (DVHs) were generated for the tumour and organs at risk (OARs). The effect of the xenographic tumour volume on the scattered out of field dose was also investigated. The defined gamma index analysis criteria were met, indicating that our MC simulation is a valid model for MC mouse phantom dose calculations. MC dose calculations showed a maximum out of field dose to the mouse of 7% of D-max. Absorbed dose to the tumour varies in the range 60%-100% of D-max. DVH analysis demonstrated that tumour received an inhomogeneous dose of 12 Gy-20 Gy (for 20 Gy prescribed dose) while out of field doses to all OARs were minimized (1.29 Gy-1.38 Gy). Variation of the xenographic tumour volume exhibited no significant effect on the out of field scattered dose to OARs. The CT derived MC mouse model presented here is a useful tool for tumour dose verifications as well as investigating the doses to normal tissue (in out of field) for preclinical radiobiological research.

    Mayeen Uddin Khandaker, S.N. Mat Nawi, S.E. Lam, D.A. Bradley, S.F. Abdul Sani, M.R.I. Faruque, Sabina Yasmin, Abubakr M. Idris (2022)Studies of defect states and kinetic parameters of car windscreen for thermoluminescence retrospective dosimetry, In: Applied radiation and isotopes186pp. 110271-110271 Elsevier Ltd

    In case of any natural disasters or technical failures of nuclear facilities, the surrounding media including human beings may receive unexpected radiation exposures. In such a situation, there is no viable way to know how much radiation dose is received by human beings. Realizing that motorized vehicles are parked at fixed but increasing distances within the nuclear installation and industrial environment, this study investigates the kinetic parameters of readily available car windscreens which form the basis to be employed in post-accident dose reconstruction or for retrospective dosimetry. To understand the luminescence features of this crystalline media, a convenient thermoluminescence (TL) technique has been employed. Several well-defined theoretical models and methods were employed to calculate the kinetic parameters including the order of kinetics (b), activation energy (E) or trap depth, frequency factor (s) or escape probability and trap lifetime (τ), by analyzing the glow curves of the irradiated samples. The analysed trapping parameters indicate that the Toyota (E = 0.75–1.31 eV, s = 3.0E+6 – 3.7E+9 (s−1), τ = 6.9E+5 – 1.3E+14 s) and Honda (E = 0.95–1.68 eV, s = 2.1E+10 – 4.1E+13 (s−1), τ = 2.2E+9 – 3.1E+20 s) windscreen offer promising features for conventional TL dosimetry applications, while the obtained longer lifetime (τ = 6.8E+10 – 8.6E+29 s) or higher activation energy (E = 1.23–2.15 eV) for Proton brand windscreen indicates better stability or slow fading of the material, thus suitable for retrospective TL dosimetry. In addition, by assessing the area of deconvoluted micro-Raman spectra of windshield glasses in high-frequency regions, it has been observed the phenomenon of dose-dependent structural alterations and internal annealing of defects. This pattern is also consistent with those cyclical pattern observed in the intensity ratio of defect and graphite modes in the studies of carbon-rich media. Such common phenomena indicate the possibility of using the Raman microspectroscopy as a probe of radiation damage in silica-based media. •Novel use of car windscreen glass sample for retrospective TL dosimetry.•TL kinetic parameters of windscreens are studied for the first time via various techniques.•Principal trapping parameters are evaluated and compared among different methods.•The data suggest that the Proton windscreen is suitable for retrospective dosimetry.

    S. N. Mohd Sobri, S. F. Abdul Sani, Siti Norbaini Sabtu, L. M. Looi, S. F. Chiew, Dharini Pathmanathan, Sirinart Chio-Srichan, D. A. Bradley (2020)Structural Studies of Epithelial Mesenchymal Transition Breast Tissues, In: Scientific reports10(1)pp. 1997-1997

    Abstract At the supramolecular level, the proliferation of invasive ductal carcinoma through breast tissue is beyond the range of standard histopathology identification. Using synchrotron small angle x-ray scattering (SAXS) techniques, determining nanometer scale structural changes in breast tissue has been demonstrated to allow discrimination between different tissue types. From a total of 22 patients undergoing symptomatic investigations, different category breast tissue samples were obtained in use of surgically removed tissue, including non-lesional, benign and malignant tumour. Structural components of the tissues were examined at momentum transfer values between q = 0.2 nm −1 and 1.5 nm −1 . From the SAXS patterns, axial d-spacing and diffuse scattering intensity were observed to provide the greatest discrimination between the various tissue types, specifically in regard to the epithelial mesenchymal transition (EMT) structural component in malignant tissue. In non-lesional tissue the axial period of collagen is within the range 63.6–63.7 nm (formalin fixed paraffin embedded (FFPE) dewaxed) and 63.4 (formalin fixed), being 0.9 nm smaller than in EMT cancer-invaded regions. The overall intensity of scattering from cancerous regions is a degree of magnitude greater in cancer-invaded regions. Present work has found that the d-spacing of the EMT positive breast cancer tissue (FFPE (dewaxed)) is within the range 64.5–64.7 nm corresponding to the 9 th and 10 th order peaks. Of particular note in regard to formalin fixation of samples is that no alteration is observed to occur in the relative differences in collagen d-spacing between non-lesional and malignant tissues. This is a matter of great importance given that preserved-sample and also retrospective study of samples is greatly facilitated by formalin fixation. Present results indicate that as aids in tissue diagnosis SAXS is capable of distinguishing areas of invasion by disease as well as delivering further information at the supramolecular level.

    Md.Refat Jahan Rakib, Y. N. Jolly, Diana Carolina Dioses-Salinas, Carlos Ivan Pizarro-Ortega, Gabriel Enrique De-la-Torre, Mayeen Uddin Khandaker, Abdullah Alsubaie, Abdulraheem S. A. Almalki, D. A. Bradley (2021)Macroalgae in biomonitoring of metal pollution in the Bay of Bengal coastal waters of Cox’s Bazar and surrounding areas, In: Scientific reports11(1)pp. 20999-20999 Nature Publishing Group UK

    Although coastal water marine algae have been popularly used by others as indicators of heavy metal pollution, data within the Bay of Bengal for the estuarine Cox’s Bazar region and Saint Martin’s Island has remained scarce. Using marine algae, the study herein forms an effort in biomonitoring of metal contamination in the aforementioned Bangladesh areas. A total of 10 seaweed species were collected, including edible varieties, analyzed for metal levels through the use of the technique of EDXRF. From greatest to least, measured mean metal concentrations in descending order have been found to be K > Fe > Zr > Br > Sr > Zn > Mn > Rb > Cu > As > Pb > Cr > Co. Potential toxic heavy metals such as Pb, As, and Cr appear at lower concentration values compared to that found for essential mineral elements. However, the presence of Pb in Sargassum oligocystum species has been observed to exceed the maximum international guidance level. Given that some of the algae species are cultivated for human consumption, the non-carcinogenic and carcinogenic indices were calculated, shown to be slightly lower than the maxima recommended by the international organizations. Overall, the present results are consistent with literature data suggesting that heavy metal macroalgae biomonitoring may be species-specific. To the best of our knowledge, this study represents the first comprehensive macroalgae biomonitoring study of metal contamination from the coastal waters of Cox’s Bazar and beyond.

    Ahmed E. Abdel Gawad, Khaled Ali, Hassan Eliwa, M. I. Sayyed, Mayeen Uddin Khandaker, David A. Bradley, Hamid Osman, Basem H. Elesawy, Mohamed Y. Hanfi (2021)Radiological investigation on sediments: A case study of wadi rod elsayalla the southeastern desert of egypt, In: Applied sciences11(24) Mdpi

    The presence of heavy radioactive minerals in the studied granitoids from which the Wadi sediments leads to the study of the exposure to emitted gamma rays from the terrestrial radionuclides, such as U-238, Th-232, and K-40. The geological study revealed that the Wadi sediments derived from the surrounding granitoids, such as syenogranite, alkali feldspar granite, and quartz syenite. The mineral analysis confirmed that the granitoids were enriched with radioactive minerals, such as uranothorite as well as monazite, zircon, yttrocolumbite, and allanite. The mean activity of the U-238, Th-232, and K-40 concentrations are 62.2 +/- 20.8, 84.2 +/- 23.3, and 949.4 +/- 172.5 Bq kg(-1), respectively, for the investigated Wadi sediments, exceeding the reported limit of 33, 45 and 412 Bq kg(-1), respectively. Public exposure to emitted gamma radiation is detected by estimating many radiological hazard indices, such as the radium equivalent content (Ra-eq), external and internal hazard indices (H-ex and H-in), annual effective dose (AED), annual gonadal dose equivalent (AGDE), and excess lifetime cancer (ELCR). The obtained results of the radiological hazards parameters showed that public exposure to emitted gamma radiation can induce various dangerous health effects. Thus, the application of the investigated sediments in different building materials and infrastructures fields is not safe. A multivariate statistical analysis (MSA) was applied to detect radionuclide correlations with the radiological hazard parameters estimated in the granite samples.

    Y. Khairi, H. Omer, A. Sulieman, N. Deiab, Maha H. Mokhtar, Fouad A. Abolaban, M. Alkhorayef, D.A. Bradley (2021)Radiation dose homogeneity and critical organs in radiotherapy treatment of prostate cancer, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    Present study compares two different 3D radiotherapy techniques: three-dimensional conformal radiotherapy (3D-CRT) and 3D external-beam radiation dose fields from computerized treatment plans, produced for 30 prostate cancer patients. All of the patients were the subject of treatment at the National Cancer Institute in Egypt. Evaluation was made of dose homogeneity within the target volume and the dose to critical organs (organs at risk, OAR). The plans were based on CT scans, all for cases of localized prostate cancer (all stage T2N0M0), with the CT scans transferred to the treatment planning systems. Comparison of the two different 3D radiation techniques was made in terms of isodose distributions and dose-volume histograms. The percentage of the planning target volume receiving 95% (V95) and 107% (V107) of the prescribed dose were obtained. For the 3D-CRT technique, the mean values for these were respectively 90.6% and 5.7% while for the other 3D technique they were 94.9% and 3.8%. In examining the dose received by the OAR, use of the 3D-CRT technique was found to provide the preferred dose distribution, with much greater sparing of the bladder, rectum and head of both femora. For the rectum the mean V70, V75 and D95 values (the latter referring to doses to 95% of the treatment volume) for the 3D-CRT technique were 35.5%, 32.2% and 34% while for the other 3D technique these were 8.4%, 0.2% and 12% respectively. For the bladder, the mean V40 and V65 values obtained using the 3D-CRT technique were 80.8% and 74.9% while for the alternative 3D technique they were 20.4% and 17% respectively. Thus for the particular cohort, the 3D-CRT technique provided superior target coverage and reduction of dose to the OAR. •Dosimetric comparison made of comparison of two different 3D-CRT and 3D techniques for treatment of prostate cancer.•Comparison performed using isodose distributions and dose-volume histograms.•3D planning provides a better target coverage and reduces dose to the OAR.

    M. Abuzaid, A. Abdelrazig, A. Sulieman, M. Alkhorayef, E. Babikir, B. Alonazi, D.A. Bradley (2020)Radiation dose to the paediatric undergoing diagnostic coronary angiography and percutaneous intervention procedures, In: Radiation physics and chemistry (Oxford, England : 1993)167 Elsevier Ltd

    Successful diagnostic and clinical outcomes in use of interventional cardiac imaging procedures make them strong choices in dealing with cardiovascular disease. Interventional procedures in developing countries are now growing markedly, increasing with the availability of equipment and trained staff. Present study in Sudan has examined pediatric radiation doses during Diagnostic Coronary Angiography (DCA) and Percutaneous Intervention Procedures (PCI), identifying relationships leading to high values, in particular with patient characteristics and exposure parameters. Retrospective data analysis from DCA cases (n = 9) and PCI (n = 48) examined patient-based characteristics, exposure parameters and the Kerma Area Product (KAP). For DCA and PCI, the mean KAP and fluoroscopic time were 4372.4 ± 3190.1 and 3877.6 ± 1249.1 cGy cm2 and 5 ± 4.7 and 5.3 ± 3.6 min respectively, with correlations between KAP and weight and KAP and fluoroscopic time of r = 0.91 and r = 0.71 respectively. The radiation dose for children during DCA and PCI is a critical issue, avoidable radiogenic risk, needing to be mitigated through optimization. •Pediatric radiation dose is a critical issue and should be optimized.•Radiation dose benchmark guideline should be available to achieve ALARA.•Monitoring of radiation dose and awareness improvement among healthcare workers.

    Awais Khalid, Pervaiz Ahmad, Abdulrahman Alharthi, Saleh Muhammad, Mayeen Uddin Khandaker, Mubasher Rehman, Mohammad Rashed Iqbal Faruque, Israf Ud Din, Mshari A. Alotaibi, Khalid Alzimami, David A. Bradley (2021)Structural, optical and antibacterial efficacy of pure and zinc-doped copper oxide against pathogenic bacteria, In: Nanomaterials (Basel, Switzerland)11(2)pp. 1-13 Mdpi

    Copper oxide and Zinc (Zn)-doped Copper oxide nanostructures (CuO-NSs) are successfully synthesized by using a hydrothermal technique. The as-obtained pure and Zn-doped CuO-NSs were tested to study the effect of doping in CuO on structural, optical, and antibacterial properties. The band gap of the nanostructures is calculated by using the Tauc plot. Our results have shown that the band gap of CuO reduces with the addition of Zinc. Optimization of processing conditions and concentration of precursors leads to the formation of pine needles and sea urchin-like nanostructures. The antibacterial properties of obtained Zn-doped CuO-NSs are observed against Gram-negative (Pseudomonas aeruginosa, Klebsiella pneumonia, Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria via the agar well diffusion method. Zn doped s are found to have more effective bacterial resistance than pure CuO. The improved antibacterial activity is attributed to the reactive oxygen species (ROS) generation.

    Noor Fadilla Ismail, Suhairul Hashim, Mohamad Syazwan Mohd Sanusi, Ahmad Taufek Abdul Rahman, David Andrew Bradley (2021)Radon levels of water sources in the southwest coastal region of Peninsular Malaysia, In: Applied sciences11(15) Mdpi

    Across populations, the dominating source of public exposure to radiation is radon gas. In the present study, we aimed at determining the concentration of radon in water sources from the southwest coastal region of Peninsular Malaysia. A total of 27 water samples were taken from various water sources which included groundwater, as well as hot spring, lake, river, seawater, and tap water; the radon concentrations were measured using a RAD7 portable radon detector. The radon concentrations ranged from 0.07 +/- 0.12 to 187 +/- 12 Bq l(-1), with an average of 21 +/- 12 Bq l(-1). The highest concentration was found in hot spring water, with an average concentration of 99 +/- 6 Bq l(-1), while the lowest concentration was found in tap water, with an average concentration of 1.95 +/- 0.61 Bq l(-1). The average concentrations of radon for all categories of sampled water were below the 100 Bq l(-1) WHO guidance level for safe drinking water. According to the ICRP effective dose conversion factor and UNSCEAR (2000), the total effective dose from the summation of inhaled and imbibed water was calculated from the aqueous radon concentrations, with an average effective dose of 4.45 mu Sv y(-1), well within the WHO safe drinking water guideline value of 100 mu Sv per year. The results of this study could support the efforts of authorities and regulators who are responsible for controlling and strategizing to ensure public safety against radon exposures.

    Abdelmoneim Sulieman, Hasan Salah, Mohammad Rabbaa, Mohammad Abuljoud, M. Alkhorayef, Dahlang Tahir, N. Tamam, Mohammed K. Saeed, D.A. Bradley (2023)Assessment of male patients’ average glandular dose during mammography procedure, In: Applied radiation and isotopes193pp. 110626-110626 Elsevier Ltd

    Breast cancer is a common malignancy for females (25% of female cancers) and also has low incidence in males. It was estimated that 1% of all breast malignancies occur in males with mortality rate about 20%, with annual increase in incidence. Risk factors include age, family history, exposure to ionizing radiation and high estrogen and low of androgens hormones level. Diagnosis and screening are challenging due to limiting effectiveness of breast cancer screening. Therefore, patients may expose to ionizing radiation that may contribute in breast cancer incidence in males. In literature, limited studies were published regarding radiation exposure for males during mammography. The objective of this research is to quantify patient doses during male mammogram and to estimate the projected radiogenic risk during the procedure. In total, 42 male patients were undergone mammogram for breast cancer diagnosis during two consecutive years. The mean and range of patient age (years) is 45 (23–80). The mean and standard deviation (SD) of the peak tube potential and tube current time product are 28.64 ± 2. and 149 ± 35.1, respectively. The mean, and range of patients' entrance surface air kerma (ESAK, mGy) per single breast procedure was 5.3 (0.47–27.5). Male patient's received comparable radiation dose per mammogram compared to female procedures. With increasing incidence of male breast cancer, proper guidelines are necessary for the mammographic procedure are necessary to reduce unnecessary radiation doses and radiogenic risk. •Average glandular doses were quantified for 42 male patients’ mammograms.•The radiogenic risk for male procedure is low compared to other procedures.•Elimination of the radiation exposure for young male and girls is recommended.•Males received comparable dose to females mammography procedure.

    Mohamed M. Abuzaid, Wiam Elshami, Abdelmoneim Sulieman, David Bradley (2022)Cumulative radiation exposure, effective and organ dose estimation from multiple head CT scans in stroke patients, In: Radiation physics and chemistry (Oxford, England : 1993)199 Elsevier

    This study aimed to estimate the cumulative radiation exposure, effective and organ dose from the recurrent computed tomography (CT) head scan during the stroke. Data was collected using a validated survey, including scanner information, patient demographic information, scan protocol, and dose indices (CTDIvol and DLP). A retrospective search of the picture archiving and communicating system (PACS) database for all the patients who underwent at least three head scans while admitted to the hospital because of stroke. Effective and organ doses are calculated by VirtualDose software based on ICRP 103. One hundred fifty-two patients underwent three to five scans during their hospitalization, which lasted from three weeks to three months. The age ranged from 45-to 76 years; males were (n = 104, 68.4%) and females were (n = 48, 35.6%). The scan range was 20.9-28.8 cm, with a mean of 24.4 +/- 1.5. The mean CTDIvol and DLP values per scan were 21 +/- 0.8 and 429 +/- 85, respectively. The calculated effective doses for patients with three, four, and five scans were 6.4, 8.5, and 10.7 mSv, respectively. The highest organ dose is recorded in the brain and the lowest at the breast. Focusing on referring physician awareness and encouraging request justification and dose optimization for patients subject to frequent radiation exams. In addition, the cumulative effective dose should be part of training programs for referrers, radiologists and radiographers.

    Mohammad Aminul Islam, Yasmin Abdu Wahab, Mayeen Uddin Khandaker, Abdullah Alsubaie, Abdulraheem S. A. Almalki, David A. Bradley, Nowshad Amin (2021)High mobility reactive sputtered CuxO thin film for highly efficient and stable perovskite solar cells, In: Crystals (Basel)11(4) Mdpi

    Copper oxide (CuxO) films are considered to be an attractive hole-transporting material (HTM) in the inverted planar heterojunction perovskite solar cells due to their unique optoelectronic properties, including intrinsic p-type conductivity, high mobility, low-thermal emittance, and energy band level matching with the perovskite (PS) material. In this study, the potential of reactive sputtered CuxO thin films with a thickness of around 100 nm has been extensively investigated as a promising HTM for effective and stable perovskite solar cells. The as-deposited and annealed films have been characterized by using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Photoluminescence (PL), UV-Vis spectroscopy, and Hall-effect measurement techniques. The significant change in structural and optoelectronic properties has been observed as an impact of the thermal annealing process. The phase conversion from Cu2O to CuO, including grain size increment, was observed upon thermal annealing. The transmittance and optical bandgap were found to vary with the films' crystallographic transformation. The predominant p-type conductivity and optimum annealing time for higher mobility have been confirmed from the Hall measurement. Films' optoelectrical properties were implemented in the complete perovskite solar cell for numerical analysis. The simulation results show that a 40 min annealed CuxO film yields the highest efficiency of 22.56% with a maximum open-circuit voltage of 1.06 V.

    Nissren Tamam, H. Salah, Kholoud S. Almogren, Omer Mahgoub, Mohammed Khalil Saeed, Yousef Abdullah, Duong Thanh Tai, Hiba Omer, Abdelmoneim Sulieman, D.A. Bradley (2023)Evaluation of patients’ and occupational radiation risk dose during conventional and interventional radiology procedures, In: Radiation physics and chemistry (Oxford, England : 1993)207 Elsevier Ltd

    Medical personnel working with ionizing radiation are exposed to significant radiation doses. Previously published studies reported increased incidence of induced cancer and cataracts among radiation workers in medical and industrial premises due to exposure to ionizing radiation. Therefore, an assessment of occupational exposure is recommended. The purpose of this study is to estimate the radiation risk caused by staff exposure and ambient exposures during diagnostic radiography. The study involved 46 staff members: 38 technologists, 8 Radiologists and 22 patients: 11 undergoing conventional radiology and 11 undergoing fluoroscopic radiology. Occupational and ambient doses were measured using calibrated optical stimulating-luminescent dosimeters (OSL) (Al2O3:C). These badges were read using an automatic OSL reader. Patients’ doses were calculated form the reading of the x-ray machines. Calculating the dose parameters for patients, the mean and standard deviation (SD) of the kVp, mAs, and patient doses in terms of Dose Area Product (DAP)were 113.1 ± 16.2, 7.5 ± 11.65, and 869.6, respectively. The mean and range of the annual effective dose (mSv) for technologists was (0.6 ± 0.36) (0–2.11). The mean and range of effective dose (mSv) for Radiologists were (0.48 ± 0.19) (0.17–0.74). The occupational exposure in this study showed that radiology technologists and radiologists are exposed to a low dose according to the current workload. The staff dose reported in this study is lower than those available in most previous studies. •Staff annual radiation dose were assessed for radiology technologists for two consecutive years.•Occupational doses were quantified with OSL dosimeters.•The occupational exposure is 90% below the annual dose limits.

    Nissren Tamam, Aljawhara H. Almuqrin, Soad Mansour, Abdelrahman Elnour, Mustafa Musa, Hiba Omer, Abdelmoneim Sulieman, D.A. Bradley (2021)Occupational and patients effective radiation doses in dental imaging, In: Applied radiation and isotopes177pp. 109899-109899 Elsevier Ltd

    Ionizing radiation exposure from medical applications is increasing annually worldwide. It was estimated that 325 million dental procedures were performed in the United States. Radiation exposure from dental radiography consists of intraoral, panoramic, and 3D imaging cone-beam computed tomography (CBCT) imaging. Recent studies reported an association between dental imaging procedures and increased cancer probability of brain and thyroid. Previous studies showed that some dental imaging practices exposed patients and staff to unnecessary radiation doses due to incorrect image acquisition and insufficient radiation protection measures. This study aims to (i) measure the occupational and patients doses during dental procedures and (ii) assess the current imaging techniques and radiation protection practices. Two hundred fourteen patients were evaluated for periapical, bitewing, cephalometric, occlusal, and panoramic procedures. Organ equivalent doses were quantified for the breast, eye lens, and thyroid gland during CBCT procedure. Occupational and ambient dose assessment were assessed using calibrated thermoluminescent dosimeters (TLD-100(LiF: Mg. Ti). Ambient doses were measure at different locations at the department using TLDs. Patients' radiation doses were quantified using kerma area product (PKA ( and the entrance surface air kerma (ESAK (mGy). Fixed tube voltage (65 kVp) and tube current-time product (7 mAs) were used. The overall mean, sd, and range of patients dose values during intraoral (mGy), panoramic and CBCT examinations were 4.6 ± 0.7 (1.4–7.1), 135 ± 45 (75.2–168.5), and 215 ± 165 (186–2115), respectively. The mean and range of the annual occupational doses (mSv) were 1.4 (0.6–3.7), which below the annual dose limits for radiation workers (20 mSv/y). The study showed that inadequate radiation protection for patients existed in terms of the use of the thyroid shield, the technologist's presence inside the room during radiation exposure. Patients' radiation doses were comparable with the international diagnostic reference level (DRL). Staff education and training in radiation protection aspects are highly recommended. •Radiation doses from intraoral, panoramic, and 3D imaging cone-beam computed tomography imaging were quantified.•Ambient and occupational doses were measure at different locations at the department using TLD.•The study showed that inadequate radiation protection for patients existed in terms of the use of the thyroid shield.•CBCT dose values, the patient radiation dose is around two times higher than for a panoramic imaging procedure.•The mean and range of the annual occupational doses (mSv) were below the annual dose limits for radiation workers.

    Mycal Dutta, Abu Montakim Tareq, Ahmed Rakib, Shafi Mahmud, Saad Ahmed Sami, Jewel Mallick, Mohammad Nazmul Islam, Mohuya Majumder, Md Zia Uddin, Abdullah Alsubaie, Abdulraheem S. A. Almalki, Mayeen Uddin Khandaker, D. A. Bradley, Md Sohel Rana, Talha Bin Emran (2021)Phytochemicals from leucas zeylanica targeting main protease of sars-cov-2: Chemical profiles, molecular docking, and molecular dynamics simulations, In: Biology (Basel, Switzerland)10(8) Mdpi

    Simple Summary Molecular docking in conjunction with molecular dynamics simulation was accomplished as they extend an ample opportunity to screen plausible inhibitors of the main protease from Leucas zeylanica. The preferential phytochemicals were identified from L. zeylanica through gas chromatography-mass spectrometry (GC-MS). The pre-eminent three identified phytochemicals exhibited toxicity by no means during the scrutinization of ADME/T prominences. Moreover, pharmacologically distinguishing characteristics and the biological activity of the lead phytochemicals were satisfying as an antiviral drug contender. Additionally, the molecular dynamics simulation exhibited thermal stability and a stable binding affinity of the protein-compound complex that referred to the appreciable efficacy of lead optimization. Therefore, the preferable phytochemicals are worth substantial evaluation in the biological laboratory to recommend plausible antiviral drug candidates. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a contemporary coronavirus, has impacted global economic activity and has a high transmission rate. As a result of the virus's severe medical effects, developing effective vaccinations is vital. Plant-derived metabolites have been discovered as potential SARS-CoV-2 inhibitors. The SARS-CoV-2 main protease (M-pro) is a target for therapeutic research because of its highly conserved protein sequence. Gas chromatography-mass spectrometry (GC-MS) and molecular docking were used to screen 34 compounds identified from Leucas zeylanica for potential inhibitory activity against the SARS-CoV-2 M-pro. In addition, prime molecular mechanics-generalized Born surface area (MM-GBSA) was used to screen the compound dataset using a molecular dynamics simulation. From molecular docking analysis, 26 compounds were capable of interaction with the SARS-CoV-2 M-pro, while three compounds, namely 11-oxa-dispiro[]undecan-1-ol (-5.755 kcal/mol), azetidin-2-one 3,3-dimethyl-4-(1-aminoethyl) (-5.39 kcal/mol), and lorazepam, 2TMS derivative (-5.246 kcal/mol), exhibited the highest docking scores. These three ligands were assessed by MM-GBSA, which revealed that they bind with the necessary M-pro amino acids in the catalytic groove to cause protein inhibition, including Ser144, Cys145, and His41. The molecular dynamics simulation confirmed the complex rigidity and stability of the docked ligand-M-pro complexes based on the analysis of mean radical variations, root-mean-square fluctuations, solvent-accessible surface area, radius of gyration, and hydrogen bond formation. The study of the postmolecular dynamics confirmation also confirmed that lorazepam, 11-oxa-dispiro[]undecan-1-ol, and azetidin-2-one-3, 3-dimethyl-4-(1-aminoethyl) interact with similar M-pro binding pockets. The results of our computerized drug design approach may assist in the fight against SARS-CoV-2.

    M. Alkhorayef, A. Sulieman, Khalid Alzahrani, Mohamed Abuzaid, Othman I. Alomair, M. Almuwannis, Salem Alghamdi, Nissren Tamam, David A. Bradley (2021)Radiation risk for patients undergoing cardiac computed tomography examinations, In: Applied radiation and isotopes168pp. 109520-109520 Elsevier Ltd

    The various technological advancements in computed tomography (CT) have resulted in remarkable growth in the use of CT imaging in clinical practice, not the least of which has been its establishment as the most valuable imaging examination for the assessment of cardiovascular system disorders. The objective of this study was to assess the effective radiation dose and radiation risk for patients during cardiac CT procedures, based on studies from four different hospitals equipped with 128 slice CT equipment. A total of eighty-three patients were investigated in this study with different clinical indications. Effective doses were also calculated using software based on Monte Carlo simulation. The mean patient age (years), weight (kg), and body mass index (BMI (kg/m2)) were 49 ± 11, 82 ± 12, and 31 ± 6, respectively. The results of the study revealed that the tube voltage (kVp) and tube current-exposure time product (mAs) ranged between 100 to 140 and 50 to 840 respectively. The overall average patient dose values for the volume CT dose index [(CTDIvol), in mGy)] and dose length product (DLP) (in mGy·cm) were 34.8 ± 15 (3.7–117.0) and 383.8 ± 354 (46.0–3277.0) respectively. The average effective dose (mSv) was 15.2 ± 8 (1.2–61.8). The radiation dose values showed wide variation between different hospitals and even within the same hospital. The results indicate the need to optimize radiation dose and to establish diagnostic reference levels (DRLs) for patients undergoing coronary computed tomography angiography (CCTA), also to harmonize the imaging protocols to ensure reduced radiation risk. •Effective radiation dose was assessed for patients during coronary computed tomography angiography (CCTA) procedure.•The dose was quantified at four different hospitals equipped with 128 slices CT equipment.•The use of effective dose to compare doses with previous studies under estimate the radiation dose.•Radiation doses are imaging protocol dependent and varied among different departments.•The results indicates the necessity to harmonies the imaging protocols to reduce the preventable radiation risk.

    Abdullah Alomary, Abdelmoneim Sulieman, Mohammed Alsufayan, Fahad Alabdurazaq, Nada Faisal, Ameera Qari, Bandar M. Alanazi, Mohammed Alsaadi, Nissren Tamam, Essam Alkhybari, David A. Bradley (2022)Evaluation of radiation exposure for patients undergoing computed tomography perfusion procedure for acute ischemic stroke, In: Radiation physics and chemistry (Oxford, England : 1993)201 Elsevier Ltd

    Computed tomography perfusion (CTP) is contrast-enhanced dynamic imaging of the brain utilized to assess the blood flow volume and transmit time to the brain's parenchyma. Stroke is the world's second greatest cause of mortality, accounting for 11% of all deaths, and a major cause of disability. Previous studies reported a high radiation dose per procedure with an eye lens equivalent dose (mGy) ranging from 81.0 mGy to 348.0 mGy. This study's objective is to evaluate patients exposure during CTP procedures. Materials and methods. Three hundred twenty patients with ischemic stroke underwent CTP were examined at King Fahad Medical City (KFMC). The imaging protocol consists of plain CT, CT angiography (CTA), CTP, Angiography. The volume CT Dose Index (CTDIvol, mGy) and dose length product (DLP, were registered from the PACS system. The effective dose calculation (E, mSv) was extrapolated using computer software. For the CTP procedure, the mean and range of DLP ( for the complete procedure, CT brain, CTA, CTA digital subtraction angiography (DSA), and CTP were 1045 (105–3072), 843 (277–1530), 470.5 (210–1356), 238.8 (105–439), 2712(2012–3072) examinations, respectively. The mean and range of the effective dose (mSv) and CTDIvol (mGy) were 13.2 (10.6–17.1), 80.5 (6.11–256), in that order. The patients' doses showed wide variation due to the selection of multiple phases of acquisition and exposure factors. The dose is higher than most previous studies. Radiation dose optimization is recommended by establishing diagnostic reference level (DRL), proper CT machine setting, and increasing operators' awareness regarding radiation risks. •Multimodal computed tomography (CT) radiation doses were quantified for 72 patients.•Multimodal consists of noncontrast, angiography, digital subtraction angiography, and Perfusion CT procedure.•Multimodal CT brain procedure resulted in an effective dose of 6–15 mSv.•The use of the CTP- DSA procedure exposes the patients to unnecessary radiation.

    Abdelmoneim Sulieman, Hussein Adam, M. Z. Mahmoud, O. Hamid, Mohammed Alkhorayef, David A. Bradley (2020)Radiogenic risk assessment for abdominal vascular computed tomography angiography, In: Radiation physics and chemistry (Oxford, England : 1993)168 Elsevier

    Computed tomography (CT) has become a prominent source of medical exposures, conduct requiring measures that mitigate radio carcinogenic risk and deterministic tissue reaction effects. The objective of present study, conducted in Sudan, has been to evaluate patient radiogenic risk during vascular CT procedures. Study was made of 485 patients, the cohort comprising 218 males (45%) and 267 females (55%) of mean age +/- 1 s.d. of 48.2 +/- 17 years (ranging from 18.0 to 93.0 years). The investigation involved nine radiology departments, covering three different CT modalities (16, 64 and 128 slice). Patient organ and effective doses were estimated using established computer software (specifically, CT-Expo, ImPACT and that of the NRPB). The range of patient dose in terms of dose length product (DLP) ( and volume CT dose index (CTDIvol (mGy) were 3.2-28.51 mGy and 257.0-9263.5, respectively. The mean and range of effective dose were 25.5 +/- 18 mSv and 4.0-138.9 mSv respectively. The wide range of doses indicates the likelihood that patients have been receiving avoidable radiation exposure, their being potential for mitigation of cancer incidence risk through further optimisation of procedures. On the basis of present study of vascular CT procedure doses, the mean risk of carcinogenesis has been estimated to be 1 in 1000 procedures.

    Mayeen Uddin Khandaker, Mehdi Hassanpour, Saeedeh Khezripour, Mohammad Reza Rezaei, Atefeh Bazghandi, Marzieh Hassanpour, Mohammad Rashed Iqbal Faruque, D.A. Bradley (2023)Investigation of the effect of 131I on blood parameters for thyroid cancer treatment, In: Radiation physics and chemistry (Oxford, England : 1993)208 Elsevier Ltd

    Hematopoiesis plays a significant role in mammals' life. Hematopoietic damage due to radiations of different arrays, such as ionizing and non-ionizing radiations, could lead to external infections, internal infections, and anemia. Different cancers' treatment using radioactive sources affects the blood parameters (i.e., mature cells, immature cells, and stem cells). In the present paper, the effect of intravascular injection of Iodine-131 (131I) on the blood parameters for thyroid cancer treatment has been investigated utilizing the MCNPX code and Runge-Kutta fourth-order method. The simulation results showed that the accumulated absorbed dose in adult phantom (ORNL whole body phantom) due to normalized intravascular injection of 1 mCi (mCi) of 131I was 1.97 × 10−2 Sv. Based on the accumulated absorbed dose, the blood parameters show a function of injected 131I activity, and their variation in the activity range of 15–300 mCi was calculated using the fourth-order Runge-Kutta method. It shows that injecting 131I with an activity of less than 150 mCi does not have much effect on blood parameters in the period of two to eight days. But, the injection of 131I with an activity greater than 150 mCi and up to a maximum value of 300 mCi, reduces blood parameters by a maximum of 21.21% in a period of two to eight days. Based on the smaller variation (in percent) of blood parameters due to the injection of low activity 131I (

    Awais Khalid, Pervaiz Ahmad, Abdulrahman Alharthi, Saleh Muhammad, Mayeen Uddin Khandaker, Mohammad Rashed Iqbal Faruque, Abdulhameed Khan, Israf Ud Din, Mshari A. Alotaibi, Khalid Alzimami, Abdulrahman A. Alfuraih, David A. Bradley (2021)Enhanced optical and antibacterial activity of hydrothermally synthesized cobalt-doped zinc oxide cylindrical microcrystals, In: Materials14(12) Mdpi

    Cobalt (Co) doped zinc oxide (ZnO) microcrystals (MCs) are prepared by using the hydrothermal method from the precursor's mixture of zinc chloride (ZnCl2), cobalt-II chloride hexahydrate (CoCl2 center dot 6H(2)O), and potassium hydroxide (KOH). The smooth round cylindrical morphologies of the synthesized microcrystals of Co-doped ZnO show an increase in absorption with the cobalt doping. The antibacterial activity of the as-obtained Co-doped ZnO-MCs was tested against the bacterial strains of gram-negative (Escherichia coli, Klebsiella pneumonia) and gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes) via the agar well diffusion method. The zones of inhibition (ZOI) for Co-doped ZnO-MCs against E. coli and K. pneumoniae were found to be 17 and 19 mm, and 15 and 16 mm against S. Aureus and S. pyogenes, respectively. The prepared Co-doped ZnO-MCs were thus established as a probable antibacterial agent against gram-negative bacterial strains.

    Ali Taheri, Mayeen Uddin Khandaker, Farhad Moradi, David Andrew Bradley (2023)A review of recent advances in the modeling of nanoparticle radiosensitization with the Geant4-DNA toolkit, In: Radiation physics and chemistry (Oxford, England : 1993)212 Elsevier Ltd

    Metallic nanoparticles are promising agents for increasing the effectiveness of radiation therapy by making cells more sensitive to radiation. High atomic number nanoparticles generate low-energy secondary electrons that initiate a cascade of physical and chemical reactions, which can lead to enhanced cell damage and tumor control. However, despite the growing interest in this area, a comprehensive understanding of the biological consequences of these reactions remains elusive due to the lack of experimental data. To address this gap, the Geant4-DNA track structure code has been used for modeling the interactions of radiation with matter at the molecular and cellular levels. The Geant4-DNA track structure code an extension of the Geant4 simulation toolkit designed for modeling the interactions of radiation with biological systems with high precision. Since the Geant4-DNA code is broadly applied for radiosensitization simulations, the authors were motivated to conduct a review of the literature and provide a comprehensive information on the current status of nanoparticle radiosensitization simulations using Geant4-DNA. This review aims to analyze and categorize the existing knowledge, identify key findings, research gaps, and challenges, and provide recommendations for future research in this area. A comprehensive search for the articles that used Geant4-DNA for nanoparticle radiosensitization was performed. A total of 50 studies met the inclusion criteria, and their simulation data and major findings are extracted. According to the literature, despite the significant contribution of the Geant4-DNA code, validating simulation results against experimental data is a primary challenge because there are limited experimental studies available. In addition, detailed modeling of nanoparticle radiosensitization require an accurate depiction of the cellular microenvironment and incorporation of chemical and biological reactions, which, in turn, demands the utilization of high-performance computers. Our analysis of the literature also reveals that most current studies are focused on gold nanoparticles with cellular distribution, and photon or proton radiations. This could emphasize the need for future research to consider other potential metallic nanoparticles in combination with various particle irradiations as well as utilization of high performance computers. •This review explores the application of Geant4-DNA in nanoparticle radiosensitization.•The paper evaluates the simulation parameters and challenges for such studies.•Recommendations on future research directions for further investigations are provided.

    M.A. Olatunji, M.U. Khandaker, M. Ladan, D.A. Bradley (2018)17 - Polypyrrole-based nanocomposite adsorbents and its application in removal of radioactive materials, In: Polymer-based Nanocomposites for Energy and Environmental Applicationspp. 465-489 Elsevier Ltd

    Conducting polymers form an important aspect of research in science and engineering due to their various interesting properties, such as inherent high flexibility, structural diversity, light weight, and mechanical stability. Among them, polypyrrole due to its facile and easy synthesis at low cost, high electric conductivity, environmental friendliness, and ease of tailoring into nanocomposites has expanded its applications beyond the original scope of conventional polymers. Considering these properties, incorporation of nanofillers in polypyrrole for fabricating polypyrrole-based nanocomposites is currently receiving immense attention as beneficial resources for developing high-efficient adsorbents for addressing environmental issues. This chapter focuses on the synthesis of polypyrrole and its nanocomposites and the key issues for achieving high performance in the treatment of liquid radioactive wastes. Survey of literature on the recent studies on the uptake of radioactive materials and their nonradioactive homologues via applications of polypyrrole-based nanocomposite adsorbents was made. Finally, general outlook of the future prospects of polypyrrole-based nanocomposites in the removal of radioactive materials and possible problems they may encounter is presented.

    M Begum, AKMM Rahman, HA Abdul-Rashid, WSW Abdullah, NM Noor, MI Zulkifli, SZ Muhamad-Yasin, KA Mat-Sharif, N Tamchek, SNM Nawi, N Wahib, YM Amin, DA Bradley (2013)Thermoluminescence response of Ge-doped optical fiber dosimeters with different core sizes, In: 4th International Conference on Photonics, ICP 2013 - Conference Proceedingpp. 291-293

    Thermoluminescence (TL) properties of five different core diameter of 6 mol% germanium (Ge) doped optical fibers have been investigated for the purpose of TL dosimetry. The optical fiber dosimeter TL properties is compared with commercially available TLD-100 chips (LiF:Mg,Ti). Samples were irradiated using Cobalt-60 standard radiation source ranging from 1Gy to 10 Gy. These fibers show good linear dose response up to 10 Gy. Highest core diameter of Ge doped optical fiber (core 100 μm) provides the best response among all fibers. We observe the larger core fiber show better response than smaller core fiber. The relative sensitivity of 100 μm core optical fiber is 0.26 ± 0.04 with respect to TLD-100 chip. © 2013 IEEE.

    R.A.S. Thomas, S. M. Jafari, D. A. Bradley, N. M. Spyrou, A. Nisbet, C.H. Clark (2014)PO-0796: Dosimetric characterisation of glass bead TLDs in proton beams, In: Radiotherapy and Oncology111(1)PO-0796pp. S58-S58 Elsevier

    Purpose/Objective: To investigate the feasibility of using glass beads as a novel thermoluminescence dosimeter (TLD) in clinical proton radiotherapy. The glass beads have several physical characteristics which suggest their suitability for use as TLDs in this area: a spherical physical shape with a hole in the middle that facilitate their use in 2D and 3D arrangements; chemically inert nature; small size of 1.5 mm diameter and 1 mm thickness; inexpensive and readily available; reusable; and importantly their TL light transparency with negligible self-attenuation which is very important for high LET beams. Proton beams have high LET and therefore can deposit dose nonuniformly across a detector. Readout of TL detectors can be influenced if any opacity is present causing self-attenuation of TL light [1], [2]. The transparency of glass beads to TL light means the beads have the potential to avoid such issues.

    ATA Rahman, E Bräuer-Krisch, T Brochard, J Adamovics, S Clowes, D Bradley, S Doran (2010)Creation of sophisticated test objects for quality assurance of optical computed tomography scanners, In: Journal of Physics: Conference Series250pp. 215-219
    AI Alalawi, A Nisbet, KS Alzimami, DA Bradley, AT Abdul Rahman, MA Barry, RP Hugtenburg (2013)Measurement of dose enhancement close to high atomic number media using optical fibre thermo luminescence dosimeters, In: Radiation Physics and Chemistry

    Present interest concerns development of a system to measure photoelectron-enhanced dose close to a tissue interface using analogue gold-coated doped silica-fibre thermo luminescence detectors and an X-ray set operating at 250 kVp. Study is made of the dose enhancement factor for various thickness of gold; measurements at a total gold thickness of 160 nm produces a mean dose enhancement factor of 3.19. To verify results, simulations of the experimental setup have been performed. © 2013 Elsevier Ltd. All rights reserved.

    M. M. Mahfuz Siraz, M. S. Alam, A. M. Jubair, S. C. Das, J. Ferdous, Z. Hossain, S. Das, Mayeen Uddin Khandaker, D. A. Bradley, Shinji Tokonami, S. Yeasmin (2023)The presence of carcinogenic radon in the Padma River water, adjacent to the Rooppur Nuclear Power Plant, In: Nuclear engineering and technology55(8)pp. 3046-3053 Korean Nuclear Soc

    Radon is a naturally occurring carcinogenic agent, poses a serious health hazard when inhaled or ingested in significant amounts. The water of the Padma river will be used as a tertiary coolant for the soon-to-be-commissioned 'Rooppur Nuclear Power Plant'. Hence, it is important to assess the radio-logical status of the river prior to the commission of this power plant. Therefore, for the first time, 25 samples of water were collected from various locations of the Padma River and analyzed for radon concentration using the RAD H2O (DURRIDGE) radon monitoring device. The radon concentrations were found in the range from 0.077 & PLUSMN; 0.036 to 0.494 & PLUSMN; 0.211 Bq/L with a mean of 0.250 & PLUSMN; 0.093 Bq/L. All the concentrations were found to be below the recommended limits of WHO (100 Bq/L) and USEPA (11.1 Bq/ L). The mean annual effective dose due to the radon exposure via inhalation and ingestion pathways were 0.638 mSv/y and 0.629 mSv/y, respectively, which were all well below the annual effective dose recommended by WHO (0.1 mSv/y). Since Bangladesh lacks a national safety limit of radon in water, this pioneering study provides baseline data on radon levels for the environment around Rooppur Nuclear Power Plant.& COPY; 2023 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY license (

    S.E. Lam, D.A. Bradley, S.N. Mat Nawi, M.U. Khandaker, S.F. Abdul Sani (2023)Carbon rich media for luminescence-based surface dosimetry and study of associated surface defects, In: Applied radiation and isotopes199110920pp. 110920-110920 Elsevier Ltd

    The present study continues research into the utilisation of carbonaceous media for medical radiation dosimetry, focusing on the effects of surface area-to-volume ratio and carbon content on structural interaction alterations and dosimetric properties in sheet- and bead-type graphitic materials (with the respective carbon content of ∼98 wt% and ∼90 wt%). Using 60Co gamma-rays and doses from 0.5 Gy to 20 Gy, the study has been made of the response of commercially available graphite in the form of 0.1 mm, 0.2 mm, 0.3 mm and 0.5 mm thick sheets, also of activated carbon beads. Confocal Raman and photoluminescence spectroscopy have been employed, examining radiation-induced structural interaction alterations. Dose-dependent variation in the Raman intensity ratio ID/IG relates to the varying dominance of defect generation and dose-driven defect annealing. Of the various thickness graphite sheets, the 0.1 mm thick medium possesses the greatest surface area-to-volume ratio. Perhaps unsurprisingly, it also exhibits the greatest thermoluminescence (TL) yield compared to that of the other carbonaceous sheet foils used herein. Moreover, the second greatest mass-normalised TL yield has been observed to be that of the porous beads, reflected in the greater defect density (ID/IG > 2) when compared to the other media, due in part to their inherent feature of large internal surface area. Considering the challenge posed in matching skin thickness with skin dose, the near tissue equivalent graphite sheets show particular promise as a skin dosimeter, sensitive as a function of depth. •Raman microspectroscopy in radiation surface damage and dose study in graphitic media.•Increase in surface area-to-volume ratio with increase in thermoluminescence yield.•Thinnest graphite gives highly linear dose response and greatest low-dose sensitivity.

    Ardiansyah Ardiansyah, Heryanto Heryanto, Bidayatul Armynah, Hassan Salah, Abdelmoneim Sulieman, David A. Bradley, Dahlang Tahir (2023)Physical, mechanical, optical, and gamma radiation shielding properties of the BaO-based glass system prepared by the melt-quench technique: A review, In: Radiation physics and chemistry (Oxford, England : 1993)210111059 Elsevier

    This article presents the physical, mechanical, optical, and radiation shielding properties of several articles discussing BaO-based glass systems prepared by the melt-quench technique. Specifically, the article discussed is an article that reports experimentally the effectiveness of BaO-based glass systems as shielding gamma-ray radiation at an energy of 0.662 MeV published since 2019. In addition, we also compare the theoretical effectiveness of several glass systems by recalculating using Phy- X/PSD based on the respective compositions reported by previous studies at several energies, namely: 0.284, 0.347, 0.662, 0.826, 1.173, 1.333, and 2.506 MeV. Based on the analysis, the Bi2O3-BaO-B2O3 glass system is the best in terms of absorbing radiation. But it still needs to be developed to get the best physical, mechanical, and optical properties. With this article, scholars can more easily determine the composition of a BaO-based glass system to be applied as a more effective and high-quality radiation shield.

    N S Mohd Nor Ihsan, S F Abdul Sani, L M Looi, P L Cheah, S F Chiew, Dharini Pathmanathan, D A Bradley (2023)A review: Exploring the metabolic and structural characterisation of beta pleated amyloid fibril in human tissue using Raman spectrometry and SAXS, In: Progress in biophysics and molecular biology182pp. 59-74
    H. T. Zubair, Yi-Fei Tan, Azmi Basaif, Adebiyi Oresegun, Hafiz Zin, David Bradley, Hairul Azhar Abdul Rashid (2022)Determination of Radiation Delivery Parameters of Medical Linear Accelerators using Data Analytics Pipeline, In: 2022 IEEE-EMBS CONFERENCE ON BIOMEDICAL ENGINEERING AND SCIENCES, IECBESpp. 40-45 IEEE

    Radiotherapy treatments involve the delivery of sharp radiation pulses of 2 to 4 microseconds duration over typical total periods of 30 to 300 seconds at a rate of up to 400 pulses per second. Recent developments in optical fiber-based radioluminescence/scintillator systems offer radiation-sensing capabilities that capture signals from individual pulses. Each of these signals has unique characteristics which provide insights into the parameters of radiation delivery. Current data acquisition methods commonly rely on hardware-based charge integration methods for radiation dose calculations and have limited utilization of the acquired data for further insights or applications. In this paper, a data analytics pipeline for the extraction and processing of data from a Ge- doped real-time dosimetry system is presented. The data, as obtained for an Elekta Synergy radiotherapy system, is then analyzed for dose distribution, dose-rates determination, and signal clustering. The gathering and processing of such time-resolved data would enable applications such as fault analysis, auto-calibration, and equipment fault prediction in medical radiation facilities in addition to enhancing the routine QA process. Clinical Relevance- This work establishes the exploratory data analysis framework for the assessment of linac signals. It derives key characteristics of the pulse delivery that can associate with dosimetry, as well as QA parameters.

    MJ Farquharson, A Al-Ebraheem, C Theodorakou, E Ryan, DA Bradley, K Gurusamy, B Davidson (2009)Measurement of K, Fe, Cu and Zn levels in secondary colorectal liver cancer and surrounding normal liver tissue, and their potential as a tissue classifier, In: X-RAY SPECTROMETRY38(2)pp. 81-88 JOHN WILEY & SONS LTD
    JCG Jeynes, M Webb, KJ Kirkby, NF Kirkby, DA Bradley (2009)Proceedings of the First International Conference on Biomedical Applications of High Energy Ion Beams Preface, In: APPLIED RADIATION AND ISOTOPES67(3)pp. 369-370 PERGAMON-ELSEVIER SCIENCE LTD
    D Malain, PH Regan, DA Bradley, M Matthews, HA Al-Sulaiti, T Santawamaitre (2012)An evaluation of the natural radioactivity in Andaman beach sand samples of Thailand after the 2004 tsunami., In: Appl Radiat Isot70(8)pp. 1467-1474

    Following the 2004 'Boxing day' tsunami, a determination has been made of the activity concentrations of (226)Ra, (232)Th and (40)K in beach sand samples which have been collected from various locations along the Andaman coast of the Thai peninsula. Use has been made of a HPGe detector-based, low-background gamma-ray counting system. The natural radioactivity levels of (226)Ra, (232)Th and (40)K measured from these samples was found to lie in the range 1.6-52.5, 0.3-73.9 and 2.8-1111.9Bq/kg respectively for the west coast and 3.5-83.1, 4.5-42.0, and 9.6-1376 Bq/kg respectively for the east coast. The radioactivity concentrations of (226)Ra, (232)Th and (40)K along the Andaman coast are comparable to that of the east coast, which was not exposed to the tsunami. The corresponding annual effective dose varies from 1.6-105.9 μSv/y with a mean value of 59.1 ± 0.3 μSv/y, significantly lower than the worldwide average as reported by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) (2000).

    AT Ramli, DA Bradley, S Hashim, H Wagiran (2009)The thermoluminescence response of doped SiO2 optical fibres subjected to alpha-particle irradiation, In: APPLIED RADIATION AND ISOTOPES67(3)pp. 428-432 PERGAMON-ELSEVIER SCIENCE LTD
    D Bradley, N Hoggard (2014)Happy New Year from BJR!, In: Br J Radiol87(1033)pp. 20130778-?
    RP Hugtenburg, AS Adegunloye, DA Bradley (2010)X-ray microbeam radiation therapy calculations, including polarisation effects, with the Monte Carlo code EGS5, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Elsevier
    NM Noor, NA Shukor, M Hussein, A Nisbet, DA Bradley (2012)Comparison of the TL fading characteristics of Ge-doped optical fibres and LiF dosimeters, In: Appl Radiat Isot70(7)pp. 1384-1387 Elsevier

    Fading is important in choosing appropriate thermoluminescence (TL) materials for particular applications. Comparison is made herein of changes due to fading in the TL yield of Ge-doped fibres and lithium fluoride (LiF) dosimeters, for varying temperature and dose. The fading is independent of dose for all investigated dosimeters while the loss in TL yield reduces for lower storage temperatures. At room temperature and for 133 days of storage, a maximum signal loss of 5% has been observed for both forms of LiF dosimeter, while 9 and 50μm core diameter Ge-doped fibres produced a loss of 11% and 8%, respectively.

    S Al-Nowais, S Doran, A Kacperek, N Krstajic, J Adamovics, D Bradley (2009)A preliminary analysis of LET effects in the dosimetry of proton beams using PRESAGE™ and optical CT, In: Applied Radiation and Isotopes67(3)pp. 415-418
    SM Alkhateeb, MH Abdelkader, DA Bradley, S Pani (2012)Breast tissue contrast-simulating materials using energy-dispersive X-ray diffraction, In: Applied Radiation and Isotopes Elsevier
    MJ Farquharson, A Al-Ebraheem, G Falkenberg, R Leek, AL Harris, DA Bradley (2008)The distribution of trace elements Ca, Fe, Cu and Zn and the determination of copper oxidation state in breast tumour tissue using mu SRXRF and mu XANES, In: PHYSICS IN MEDICINE AND BIOLOGY53(11)pp. 3023-3037 IOP PUBLISHING LTD
    DA Bradley, GA Mandiraji, M Ghomeishi, E Dermosesian, FRM Adikan, HAA Rashid, MJ Maah (2015)Enhancing the radiation dose detection sensitivity of optical fibres, In: APPLIED RADIATION AND ISOTOPES100pp. 43-49 PERGAMON-ELSEVIER SCIENCE LTD
    NA Zahaimi, H Zin, GA Mahdiraji, ALA Rahman, DA Bradley, ATA Rahman (2014)Characterisation of the thermoluminescence (TL) properties of tailor-made Ge-doped silica glass fibre for applications in medical radiation therapy dosimetry, In: HM Zin, ATA Rahman, NA Kadri, R Zainon (eds.), 9TH NATIONAL SEMINAR ON MEDICAL PHYSICS (NSMP2014)546ARTN 01201 IOP PUBLISHING LTD
    M S Alam, M M Mahfuz Siraz, Jubair A M, S C Das, D A Bradley, Mayeen Uddin Khandaker, Shinji Tokonami, Afroza Shelley, Selina Yeasmin (2023)A study on measuring the 222Rn in the Buriganga River and tap water of the megacity Dhaka, In: PloS one18(5)pp. e0286267-e0286267
    NH Yaakob, H Wagiran, MI Hossain, AT Ramli, DA Bradley, S Hashim, H Ali (2011)Thermoluminescence response of Ge- and Al-doped optical fibers subjected to low-dose electron irradiation, In: Journal of Nuclear Science and Technology48(7)pp. 1115-1117
    SJ Doran, AT Abdul Rahman, E Bräuer-Krisch, T Brochard, J Adamovics, A Nisbet, D Bradley (2013)Establishing the suitability of quantitative optical CT microscopy of PRESAGE® radiochromic dosimeters for the verification of synchrotron microbeam therapy., In: Phys Med Biol58(18)pp. 6279-6297

    Previous research on optical computed tomography (CT) microscopy in the context of the synchrotron microbeam has shown the potential of the technique and demonstrated high quality images, but has left two questions unanswered: (i) are the images suitably quantitative for 3D dosimetry? and (ii) what is the impact on the spatial resolution of the system of the limited depth-of-field of the microscope optics? Cuvette and imaging studies are reported here that address these issues. Two sets of cuvettes containing the radiochromic plastic PRESAGE® were irradiated at the ID17 biomedical beamline of the European Synchrotron Radiation facility over the ranges 0-20 and 0-35 Gy and a third set of cuvettes was irradiated over the range 0-20 Gy using a standard medical linac. In parallel, three cylindrical PRESAGE® samples of diameter 9.7 mm were irradiated with test patterns that allowed the quantitative capabilities of the optical CT microscope to be verified, and independent measurements of the imaging modulation transfer function (MTF) to be made via two different methods. Both spectrophotometric analysis and imaging gave a linear dose response, with gradients ranging from 0.036-0.041 cm(-1) Gy(-1) in the three sets of cuvettes and 0.037 (optical CT units) Gy(-1) for the imaging. High-quality, quantitative imaging results were obtained throughout the 3D volume, as illustrated by depth-dose profiles. These profiles are shown to be monoexponential, and the linear attention coefficient of PRESAGE® for the synchrotron-generated x-ray beam is measured to be (0.185 ± 0.02) cm(-1) in excellent agreement with expectations. Low-level (

    SN Sabtu, RH Mahat, YM Amin, DM Price, DA Bradley, MJ Maah (2015)Thermo luminescence dating analysis at the site of an ancient brick structure at Pengkalan Bujang, Malaysia, In: APPLIED RADIATION AND ISOTOPES105pp. 182-187 PERGAMON-ELSEVIER SCIENCE LTD
    AL Palmer, DA Bradley, A Nisbet (2014)Dosimetric audit in brachytherapy, In: BRITISH JOURNAL OF RADIOLOGY87(1041)ARTN 2pp. ?-? BRITISH INST RADIOLOGY
    S Hashim, S Al-Ahbabi, DA Bradley, M Webb, C Jeynes, AT Ramli, H Wagiran (2009)The thermoluminescence response of doped SiO2 optical fibres subjected to photon and electron irradiations, In: APPLIED RADIATION AND ISOTOPES67(3)pp. 423-427 PERGAMON-ELSEVIER SCIENCE LTD
    YM Amin, MU Khandaker, AKS Shyen, RH Mahat, RM Nor, DA Bradley (2013)Radionuclide emissions from a coal-fired power plant, In: APPLIED RADIATION AND ISOTOPES80pp. 109-116 PERGAMON-ELSEVIER SCIENCE LTD

    Dose distribution measurement in clinical high dose rate (HDR) brachytherapy is challenging, because of the high dose gradients, large dose variations, and small scale, but it is essential to verify accurate treatment planning and treatment equipment performance. The authors compare and evaluate three dosimetry systems for potential use in brachytherapy dose distribution measurement: Ge-doped optical fibers, EBT3 Gafchromic film with multichannel analysis, and the radiochromic material PRESAGE(®) with optical-CT readout.

    A Alawiah, S Bauk, MW Marashdeh, KS Ng, HA Abdul-Rashid, Z Yusoff, W Gieszczyk, MN Noramaliza, GA Mahdiraji, N Tamchek, SZ Muhd-Yassin, KA Mat-Sharif, MI Zulkifli, MJ Maah, SSC Omar, DA Bradley (2015)Thermoluminescence glow curves and deconvoluted glow peaks of Ge doped flat fibers at ultra-high doses of electron radiation, In: RADIATION PHYSICS AND CHEMISTRY113pp. 53-58 PERGAMON-ELSEVIER SCIENCE LTD
    SM Jafari, TJ Jordan, G Distefano, DA Bradley, NM Spyrou, A Nisbet, CH Clark (2015)Feasibility of using glass-bead thermoluminescent dosimeters for radiotherapy treatment plan verification, In: BRITISH JOURNAL OF RADIOLOGY88(1055)ARTN 20140 BRITISH INST RADIOLOGY
    Anne Skeldon, G Chaffey, David Lloyd, V Mohan, DA Bradley, A Nisbet (2012)Modelling and detecting tumour oxygenation levels., In: PLoS One7(6)pp. e38597-?

    Tumours that are low in oxygen (hypoxic) tend to be more aggressive and respond less well to treatment. Knowing the spatial distribution of oxygen within a tumour could therefore play an important role in treatment planning, enabling treatment to be targeted in such a way that higher doses of radiation are given to the more radioresistant tissue. Mapping the spatial distribution of oxygen in vivo is difficult. Radioactive tracers that are sensitive to different levels of oxygen are under development and in the early stages of clinical use. The concentration of these tracer chemicals can be detected via positron emission tomography resulting in a time dependent concentration profile known as a tissue activity curve (TAC). Pharmaco-kinetic models have then been used to deduce oxygen concentration from TACs. Some such models have included the fact that the spatial distribution of oxygen is often highly inhomogeneous and some have not. We show that the oxygen distribution has little impact on the form of a TAC; it is only the mean oxygen concentration that matters. This has significant consequences both in terms of the computational power needed, and in the amount of information that can be deduced from TACs.

    GA Mahdiraji, E Dermosesian, MJ Safari, FRM Adikan, DA Bradley (2015)Collapsed-Hole Ge-Doped Photonic Crystal Fiber as a Diagnostic Radiation Dosimeter, In: JOURNAL OF LIGHTWAVE TECHNOLOGY33(16)pp. 3439-3445 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    AI Alalawi, SM Jafari, MA Najem, A Nisbet, M Hussein, KS Alzimami, DA Bradley, NM Spyrou, W Alsaleh, RP Hugtenburg, CH Clark, F Abolaban (2014)Preliminary investigations of two types of silica-based dosimeter for small-field radiotherapy, In: Radiation Physics and Chemistry104pp. 139-144

    Two thermoluminescent dosimeters (SiO-GeO doped fibres and glass beads (GB)) were used to measure small photon field doses and compared against GAFCHROMIC film, a small ionisation chamber (RK-018) and a p-type silicon diode (SCANDITRONIX, F1356), as well as Monte Carlo simulations with FLUKA and BEAMnrc/DOSXYZnrc. Ge-doped SiO fibres have been shown by this group to offer a viable system for use as dosimeters. The fibres and GB offer good spatial resolution (~120μm and 2mm respectively), large dynamic dose range (with linearity from tens of mGy up to well in excess of many tens of Gy), are non-hygroscopic and are of low cost. Measurements of beam profiles for field sizes of 10mm×10mm, 20mm×20mm, 30mm×30mm, 40mm×40mm, and 100mm×100mm were carried out. Through the use of a customised solid water phantom, doped optical fibres and GBs were placed at defined positions along the x-and y-axes to allow accurate beam profile measurement. The maximum difference between FWHM measurements was 1.8mm. For penumbra measurements (measured between 80% and 20% isodoses), the maximum difference was

    A Alawiah, AM Intan, S Bauk, HA Abdul-Rashid, Z Yusoff, MR Mokhtar, WSW Abdullah, KAM Sharif, GA Mahdiraji, FRM Adikan, N Tamchek, NM Noor, DA Bradley (2013)Thermoluminescence characteristics of flat optical fiber in radiation dosimetry under different electron irradiation conditions, In: K Kalli, J Kanka, A Mendez (eds.), MICRO-STRUCTURED AND SPECIALTY OPTICAL FIBRES II8775UNSP 87750 SPIE-INT SOC OPTICAL ENGINEERING
    S Hashim, MHA Mhareb, SK Ghoshal, YSM Alajerami, DA Bradley, MI Saripan, N Tamchek, K Alzimami (2015)Luminescence characteristics of Li2O-MgO-B2O3 doped with Dy3+ as a solid TL detector, In: RADIATION PHYSICS AND CHEMISTRY116pp. 138-141 PERGAMON-ELSEVIER SCIENCE LTD
    N Alazemi, AD Bajoga, DA Bradley, PH Regan, H Shams (2016)Soil radioactivity levels, radiological maps and risk assessment for the state of Kuwait., In: Chemosphere154pp. 55-62 Elsevier

    An evaluation of the radioactivity levels associated with naturally occurring radioactive materials has been undertaken as part of a systematic study to provide a surface radiological map of the State of Kuwait. Soil samples from across Kuwait were collected, measured and analysed in the current work. These evaluations provided soil activity concentration levels for primordial radionuclides, specifically members of the (238)U and (232)Th decay chains and (40)K which. The (238)U and (232)Th chain radionuclides and (40)K activity concentration values ranged between 5.9 ↔ 32.3, 3.5 ↔ 27.3, and 74 ↔ 698 Bq/kg respectively. The evaluated average specific activity concentrations of (238)U, (232)Th and (40)K across all of the soil samples have mean values of 18, 15 and 385 Bq/kg respectively, all falling below the worldwide mean values of 35, 40 and 400 Bq/kg respectively. The radiological risk factors are associated with a mean of 33.16 ± 2.46 nG/h and 68.5 ± 5.09 Bq/kg for the external dose rate and Radium equivalent respectively. The measured annual dose rates for all samples gives rise to a mean value of 40.8 ± 3.0 μSv/y while the internal and internal hazard indices have been found to be 0.23 ± 0.02 and 0.19 ± 0.01 respectively.

    DA Bradley, S Hashim, J Cabello, K Wells, WL Dunn (2010)Photon-induced positron annihilation for standoff bomb detection, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT619(1-3)pp. 415-418 ELSEVIER SCIENCE BV
    O Gundogdu, EC Ismail, RM Jenneson, DA Bradley (2009)Making Clear the Imperceptible: In-Line X-ray Phase Contrast Imaging, In: ADVANCED SCIENCE LETTERS2(1)pp. 78-80 AMER SCIENTIFIC PUBLISHERS
    AL Palmer, D Bradley, A Nisbet, P Diez, L Gandon, A Wynn-Jones, P Bownes, C Lee, E Aird, M Bidmead, G Lowe (2015)A multicentre 'end to end' dosimetry audit for cervix HDR brachytherapy treatment, In: Radiotherapy and Oncology114(2)pp. 264-271

    Purpose To undertake the first multicentre fully 'end to end' dosimetry audit for HDR cervix brachytherapy, comparing planned and delivered dose distributions around clinical treatment applicators, with review of local procedures. Materials and methods A film-dosimetry audit was performed at 46 centres, including imaging, applicator reconstruction, treatment planning and delivery. Film dose maps were calculated using triple-channel dosimetry and compared to RTDose data from treatment planning systems. Deviations between plan and measurement were quantified at prescription Point A and using gamma analysis. Local procedures were also discussed. Results The mean difference between planned and measured dose at Point A was -0.6% for plastic applicators and -3.0% for metal applicators, at standard uncertainty 3.0% (k = 1). Isodose distributions agreed within 1 mm over a dose range 2-16 Gy. Mean gamma passing rates exceeded 97% for plastic and metal applicators at 3% (local) 2 mm criteria. Two errors were found: one dose normalisation error and one applicator library misaligned with the imaged applicator. Suggestions for quality improvement were also made. Conclusions The concept of 'end to end' dosimetry audit for HDR brachytherapy has been successfully implemented in a multicentre environment, providing evidence that a high level of accuracy in brachytherapy dosimetry can be achieved.

    K Geraki, MJ Farquharson, DA Bradley, O Gundogdu, G Falkenberg (2008)The localisation of biologically important metals in soft and calcified tissues using a synchrotron x-ray fluorescence technique, In: X-RAY SPECTROMETRY37(1)pp. 12-20 JOHN WILEY & SONS LTD
    M Begum, AKMM Rahman, HA Abdul-Rashid, Z Yusoff, KA Mat-Sharif, MI Zulkifli, SZ Muhamad-Yasin, NM Ung, ABA Kadir, YM Amin, DA Bradley (2015)Comparison of thermoluminescence response of different sized Ge-doped flat fibers as a dosimeter, In: RADIATION PHYSICS AND CHEMISTRY116pp. 155-159 PERGAMON-ELSEVIER SCIENCE LTD
    MH Abdelkader, SM Alkhateeb, DA Bradley, S Pani (2012)Development and characterization of a laboratory based X-ray diffraction imaging system for material and tissue characterization., In: Appl Radiat Isot70(7)pp. 1325-1330 Elsevier

    Soft tissues feature a degree of short-range order, giving rise to diffraction patterns with broader peaks than crystalline materials. For this reason, an X-ray diffraction system (XRD) for characterization of soft tissue has less stringent requirements in terms of momentum transfer resolution than the one aimed at characterizing crystalline materials. We present results on the characterization of two energy-dispersive XRD systems. The first was based on conical collimation at 5.9° and the second was based on linear collimation at varying angles between 2° and 10°. The systems include a CdTe detector and a W-anode X-ray source. The angular resolution was measured as a function of sample thickness and scattering angle. Preliminary results confirm the effectiveness of the method for the characterization of biological tissues, showing insensitivity to small changes in angular acceptance and sample thickness, also showing it is possible to combine scattering data obtained at different angles.

    MI Saripan, WHM Saad, S Hashim, ATA Rahman, K Wells, DA Bradley (2013)Analysis of Photon Scattering Trends for Material Classification Using Artificial Neural Network Models, In: IEEE TRANSACTIONS ON NUCLEAR SCIENCE60(2)pp. 515-519 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    FCA Da Silva, David Bradley, Patrick Regan, Z Siti Rozaila (2016)Measurement of the total activity concentrations of Libyan oil scale, In: Radiation Physics and Chemistry137pp. 198-202 Elsevier

    Twenty-three oil scale samples obtained from the Libyan oil and gas industry production facilities onshore have been measured using high-resolution gamma-ray spectrometry with a shielded HPGe detector, the work being carried out within the Environmental Radioactivity Laboratory at the University of Surrey. The main objectives of this work were to determine the extent to which the predominant radionuclides associated with the uranium and thorium natural decay chains were in secular equilibrium with their decay progeny, also to compare differences between the total activity concentrations (TAC) in secular equilibrium and disequilibrium and to evaluate the measured activities for the predominant gamma-ray emitting decay radionuclides within the 232Th and 238U chains. The oil scale NORM samples did not exhibit radioactive equilibrium between the decay progeny and longer-lived parent radionuclides of the 238U and 232Th series.

    SS Al-Ahbabi, David Bradley, Andrew Nisbet (2013)Tomotherapy evaluation for head and neck cases using two types of phantoms, In: Radiation Physics and Chemistry95pp. 323-325 Elsevier

    The use of rotational therapy as an important method of treatment delivery is expected to increase due in a large part to the development and utilisation of tomotherapy. Rotational therapy minimises the occurrence of hotspots and the irradiation of critical organs, providing more uniform dosing while sparing critical organs. Two important characteristics of rotational radiation are its dynamic nature and dosimetric variability in radiation delivery, both of which present a considerable challenge for clinical physicists seeking appropriate tools to meet the demands of quality assurance.In this paper 15 Delivery Quality Assurance (DQA) plans of head and neck patients were assessed for the Hi-Art tomotherapy system using Kodak X-Omat V film and an A1SL Ref F92722 ion chamber versus MapCheck. Absolute dose measurement showed average differences of 3.42. cGy and 98% Gamma (γ) factor for the Cheese phantom technique. For the MapCheck technique the average difference and Gamma factor were 0.74. cGy and 96%, respectively. Gamma (γ) matrix distribution was used to evaluate the difference between measured and calculated dose distribution. © 2013 Elsevier Ltd.

    UA Tarim, EN Ozmutlu, O Gurler, S Yalcin, O Gundogdu, JM Sharaf, DA Bradley (2013)Monte Carlo modelling of single and multiple Compton scattering profiles in a concrete material, In: RADIATION PHYSICS AND CHEMISTRY85pp. 12-17 PERGAMON-ELSEVIER SCIENCE LTD
    DA Bradley, K Wells (2014)Reprint of: Biomedical applications reviewed: Hot topic areas, In: Radiation Physics and Chemistry95pp. 191-201

    Making reference to the British Journal of Radiology and competitor journal titles, we look at the general area of biomedical physics, reviewing some of the associated topics in ionising radiation research attracting interest over the past 2 years. We also reflect on early developments that have paved the way for these endeavours. The talk is illustrated by referring to a number of biomedical physics areas in which this group has been directly involved, including novel imaging techniques that address compositional and structural makeup as well as use of elastically scattered X-ray phase contrast, radiation damage linking to possible pericardial effects in radiotherapy, simulation of microvascularity and oxygenation with a focus of radiation resistant hypoxic tumours, issues of high spatial resolution dosimetry and tissue interface radiotherapy with doses enhanced through use of high atomic number photoelectron conversion media. © 2013 Elsevier Ltd.

    W Kaabar, E Daar, O Gundogdu, PM Jenneson, MJ Farquharson, M Webb, C Jeynes, DA Bradley (2009)Metal deposition at the bone-cartilage interface in articular cartilage, In: APPLIED RADIATION AND ISOTOPES67(3)pp. 475-479 PERGAMON-ELSEVIER SCIENCE LTD

    A novel phantom is presented for 'full system' dosimetric audit comparing planned and delivered dose distributions in HDR gynaecological brachytherapy, using clinical treatment applicators. The brachytherapy applicator dosimetry test object consists of a near full-scatter water tank with applicator and film supports constructed of Solid Water, accommodating any typical cervix applicator. Film dosimeters are precisely held in four orthogonal planes bisecting the intrauterine tube, sampling dose distributions in the high risk clinical target volume, points A and B, bladder, rectum and sigmoid. The applicator position is fixed prior to CT scanning and through treatment planning and irradiation. The CT data is acquired with the applicator in a near clinical orientation to include applicator reconstruction in the system test. Gamma analysis is used to compare treatment planning system exported RTDose grid with measured multi-channel film dose maps. Results from two pilot audits are presented, using Ir-192 and Co-60 HDR sources, with a mean gamma passing rate of 98.6% using criteria of 3% local normalization and 3 mm distance to agreement (DTA). The mean DTA between prescribed dose and measured film dose at point A was 1.2 mm. The phantom was funded by IPEM and will be used for a UK national brachytherapy dosimetry audit.

    James Scuffham, M Yip-Braidley, AL Shutt, PJ Hinton, Andrew Nisbet, David Bradley (2016)Adapting clinical gamma cameras for body monitoring in the event of a large-scale radiological incident, In: JOURNAL OF RADIOLOGICAL PROTECTION36(2)pp. 363-381 IOP PUBLISHING LTD

    After a release of radionuclides, accidental or otherwise, there will be an urgent need to identify members of the general public who have received a significant intake of radioactive material, sufficient to require medical treatment or further investigation. A large number of people could be contaminated in such an incident. For gamma-ray emitting radionuclides this screening could be carried out using gamma camera medical imaging systems, such as those that are present in many large UK hospital sites. By making a number of simple reversible changes such as removal of collimators, these cameras could be employed as useful additional screening instruments as well as an aid in contamination control. A study was carried out to investigate which systems were present in sufficient number to offer wide scale coverage of UK population centres. Nine gamma cameras (eight dual head and one single head) were assessed using point source and bottle mannequin (BOMAB) phantom measurements so that a mathematical model could be developed for use with the MCNPX Monte Carlo radiation transport code. The gamma camera models were assessed for practical seated and supine geometries to give calibration factors for a list of target radionuclides that could be released in a radiological incident. The minimum detectable activities (MDAs) that were achieved for a five minute measurement demonstrated that these systems are sufficiently sensitive to be used for screening of the general public and are comparable to other body monitoring facilities. While gamma cameras have on-board software that are designed for imaging and provide for a gamma-ray energy range suitable for radionuclides for diagnostic imaging (such as 99mTc), they are not as versatile as custom-built body monitoring systems.

    David Bradley, RP Hugtenburg, Andrew Nisbet, AT Abdul Rahman, F Issa, N Mohd Noor, A Alalawi (2012)Review of doped silica glass optical fibre: Their TL properties and potential applications in radiation therapy dosimetry, In: Applied Radiation and Isotopes71(SUPPL.)pp. 2-11 Elsevier

    Review is made of dosimetric studies of Ge-doped SiO telecommunication fibre as a 1-D thermoluminescence (TL) system for therapeutic applications. To-date, the response of these fibres has been investigated for UV sources, superficial X-ray beam therapy facilities, a synchrotron microbeam facility, electron linear accelerators, protons, neutrons and alpha particles, covering the energy range from a few eV to several MeV. Dosimetric characteristics include, reproducibility, fading, dose response, reciprocity between TL yield and dose-rate and energy dependence. The fibres produce a flat response to fixed photon and electron doses to within better than 3% of the mean TL distribution. Irradiated Ge-doped SiO optical fibres show limited signal fading, with an average loss of TL signal of ~0.4% per day. In terms of dose response, Ge-doped SiO optical fibres have been shown to provide linearity to x and electron doses, from a fraction of 1Gy up to 2kGy. The dosimeters have also been used in measuring photoelectron generation from iodinated contrast media; TL yields being some 60% greater in the presence of iodine than in its absence. The review is accompanied by previously unpublished data. © 2012 Elsevier Ltd.

    A Palmer, D Bradley, A Nisbet (2012)Physics-aspects of dose accuracy in high dose rate (HDR) brachytherapy: Source dosimetry, treatment planning, equipment performance and in vivo verification techniques, In: Journal of Contemporary Brachytherapy4(2)pp. 81-91 Termedia Publishing House

    This study provides a review of recent publications on the physics-aspects of dosimetric accuracy in high dose rate (HDR) brachytherapy. The discussion of accuracy is primarily concerned with uncertainties, but methods to improve dose conformation to the prescribed intended dose distribution are also noted. The main aim of the paper is to review current practical techniques and methods employed for HDR brachytherapy dosimetry. This includes work on the determination of dose rate fields around brachytherapy sources, the capability of treatment planning systems, the performance of treatment units and methods to verify dose delivery. This work highlights the determinants of accuracy in HDR dosimetry and treatment delivery and presents a selection of papers, focusing on articles from the last five years, to reflect active areas of research and development. Apart from Monte Carlo modelling of source dosimetry, there is no clear consensus on the optimum techniques to be used to assure dosimetric accuracy through all the processes involved in HDR brachytherapy treatment. With the exception of the ESTRO mailed dosimetry service, there is little dosimetric audit activity reported in the literature, when compared with external beam radiotherapy verification.

    SM Jafari, AI Alalawi, M Hussein, W Alsaleh, MA Najem, RP Hugtenburg, DA Bradley, NM Spyrou, CH Clark, A Nisbet (2014)Glass beads and Ge-doped optical fibres as thermoluminescence dosimeters for small field photon dosimetry, In: PHYSICS IN MEDICINE AND BIOLOGY59(22)pp. 6875-6889 IOP PUBLISHING LTD
    SA Ibrahim, SSC Omar, S Hashim, GA Mahdiraji, DA Bradley, AB Kadir, NM Isa (2014)Assessment of Ge-doped optical fibres subjected to x-ray irradiation, In: HM Zin, ATA Rahman, NA Kadri, R Zainon (eds.), 9TH NATIONAL SEMINAR ON MEDICAL PHYSICS (NSMP2014)546ARTN 01201 IOP PUBLISHING LTD
    AI Alalawi, Andrew Nisbet, KS Alzimami, David Bradley, RP Hugtenburg, AT Abdul Rahman, MA Barry (2014)Measurement of dose enhancement close to high atomic number media using optical fibre thermoluminescence dosimeters, In: Radiation Physics and Chemistry95pp. 145-147

    Present interest concerns development of a system to measure photoelectron-enhanced dose close to a tissue interface using analogue gold-coated doped silica-fibre thermoluminescence detectors and an X-ray set operating at 250. kVp. Study is made of the dose enhancement factor for various thicknesses of gold; measurements at a total gold thickness of 160. nm (accounting for incident and exiting photons) produces a mean measured dose enhancement factor of 1.33±0.01 To verify results, simulations of the experimental setup have been performed. © 2013 Elsevier Ltd.

    N Abuhadi, D Bradley, D Katarey, Z Podolyak, S Sassi (2014)Investigation of the quantitative accuracy of 3D iterative reconstruction algorithms in comparison to filtered back projection method: a phantom study, In: BR Whiting, C Hoeschen, D Kontos (eds.), MEDICAL IMAGING 2014: PHYSICS OF MEDICAL IMAGING9033ARTN 90335 SPIE-INT SOC OPTICAL ENGINEERING
    A.A Almahwasi, J.C. Jeynes, M.J. Merchant, D.A. Bradley, P.H. Regan (2016)Delayed persistence of giant-nucleated cells induced by X-ray and proton irradiation in the progeny of replicating normal human fibroblast cells, In: Radiation Physics and Chemistry137pp. 163-168 Elsevier

    Ionising radiation can induce giant-nucleated cells (GCs) in the progeny of irradiated populations, as demonstrated in various cellular systems. Most in vitro studies have utilised quiescent cancerous or normal cell lines but it is not clear whether radiation-induced GCs persist in the progeny of normal replicated cells. In the current work we show persistent induction of GCs in the progeny of normal human-diploid skin fibroblasts (AG1522). These cells were originally irradiated with a single equivalent clinical dose of 0.2, 1 or 2 Gy of either X-ray or proton irradiation and maintained in an active state for various post-irradiation incubation interval times before they were replated for GC analysis. The results demonstrate that the formation of GCs in the progeny of X-ray or proton irradiated cells was increased in a dose-dependent manner when measured 7 days after irradiation and this finding is in agreement with that reported for the AG1522 cells using other radiation qualities. For the 1 Gy X-ray doses it was found that the GC yield increased continually with time up to 21 days post-irradiation. These results can act as benchmark data for such work and may have important implications for studies aimed at evaluating the efficacy of radiation therapy and in determining the risk of delayed effects particularly when applying protons.

    CJ Moger, R Barrett, P Bleuet, DA Bradley, RE Ellis, EM Green, KM Knapp, P Muthuvelu, CP Winlove (2007)Regional variations of collagen orientation in normal and diseased articular cartilage and subchondral bone determined using small angle X-ray scattering (SAXS), In: OSTEOARTHRITIS AND CARTILAGE15(6)pp. 682-687 W B SAUNDERS CO LTD
    B Müller, H Deyhle, DA Bradley, M Farquharson, G Schulz, M Müller-Gerbl, O Bunk (2010)Scanning X-ray scattering: Evaluating the nanostructure of human tissues, In: European Journal of Nanomedicine3(1)pp. 30-33
    N Mohd Noor, Andrew Nisbet, M Hussein, S Sarene Chu, T Kadni, N Abdullah, David Bradley (2017)Dosimetry Audits and Intercomparisons in Radiotherapy: a Malaysian Profile, In: Radiation Physics and Chemistry140pp. 207-212 Elsevier

    Quality audits and intercomparisons are important in ensuring control of processes in any system of endeavour. Present interest is in control of dosimetry in teletherapy, there being a need to assess the extent to which there is consistent radiation dose delivery to the patient. In this study we review significant factors that impact upon radiotherapy dosimetry, focusing upon the example situation of radiotherapy delivery in Malaysia, examining existing literature in support of such efforts. A number of recommendations are made to provide for increased quality assurance and control. In addition to this study, the first level of intercomparison audit i.e. measuring beam output under reference conditions at eight selected Malaysian radiotherapy centres is checked; use being made of 9 µm core diameter Ge-doped silica fibres (Ge-9 µm). The results of Malaysian Secondary Standard Dosimetry Laboratory (SSDL) participation in the IAEA/WHO TLD postal dose audit services during the period between 2011 and 2015 will also been discussed. In conclusion, following review of the development of dosimetry audits and the conduct of one such exercise in Malaysia, it is apparent that regular periodic radiotherapy audits and intercomparison programmes should be strongly supported and implemented worldwide. The programmes to-date demonstrate these to be a good indicator of errors and of consistency between centres. A total of ei+ght beams have been checked in eight Malaysian radiotherapy centres. One out of the eight beams checked produced an unacceptable deviation; this was found to be due to unfamiliarity with the irradiation procedures. Prior to a repeat measurement, the mean ratio of measured to quoted dose was found to be 0.99 with standard deviation of 3%. Subsequent to the repeat measurement, the mean distribution was 1.00, and the standard deviation was 1.3%.

    SM Jafari, DA Bradley, A Alalawi, CH Clark, A Nisbet, NM Spyrou, CA Gouldstone, PHG Sharpe, TJ Jordan (2014)Low-cost commercial glass beads as dosimeters in radiotherapy, In: Radiation Physics and Chemistry97pp. 95-101

    Recent developments in advanced radiotherapy techniques using small field photon beams, require small detectors to determine the delivered dose in steep dose gradient fields. Commercially available glass jewellery beads exhibit thermoluminescent properties and have the potential to be used as dosimeters in radiotherapy due to their small size (

    AD Bajoga, N Alazemi, PH Regan, DA Bradley (2015)Radioactive investigation of NORM samples from Southern Kuwait soil using high-resolution gamma-ray spectroscopy, In: RADIATION PHYSICS AND CHEMISTRY116pp. 305-311 PERGAMON-ELSEVIER SCIENCE LTD
    DA Bradley, RP Hugtenburg, AL Yusoff (2006)Near-edge elastic photon scattering from dilute aqueous ions, In: RADIATION PHYSICS AND CHEMISTRY75(12)pp. 2129-2135 PERGAMON-ELSEVIER SCIENCE LTD
    DA Bradley, K Wells (2013)Biomedical applications reviewed: Hot topic areas, In: Radiation Physics and Chemistry

    Making reference to the British Journal of Radiology and competitor journal titles, we look at the general area of biomedical physics, reviewing some of the associated topics in ionising radiation research attracting interest over the past 2 years. We also reflect on early developments that have paved the way for these endeavours. The talk is illustrated by referring to a number of biomedical physics areas in which this group has been directly involved, including novel imaging techniques that address compositional and structural makeup as well as use of elastically scattered X-ray phase contrast, radiation damage linking to possible pericardial effects in radiotherapy, simulation of microvascularity and oxygenation with a focus of radiation resistant hypoxic tumours, issues of high spatial resolution dosimetry and tissue interface radiotherapy with doses enhanced through use of high atomic number photoelectron conversion media. © 2012 Elsevier Ltd. All rights reserved.

    M Ghomeishi, GA Mahdiraji, FRM Adikan, NM Ung, DA Bradley (2015)Sensitive Fibre-Based Thermoluminescence Detectors for High Resolution In-Vivo Dosimetry, In: SCIENTIFIC REPORTS5ARTN 13309 NATURE PUBLISHING GROUP
    M Begum, AKMM Rahman, HA Abdul-Rashid, Z Yusoff, M Begum, KA Mat-Sharif, YM Amin, DA Bradley (2015)Thermoluminescence characteristics of Ge-doped optical fibers with different dimensions for radiation dosimetry, In: APPLIED RADIATION AND ISOTOPES100pp. 79-83 PERGAMON-ELSEVIER SCIENCE LTD
    AT Abdul Rahman, RP Hugtenburg, SF Abdul Sani, AI Alalawi, F Issa, R Thomas, MA Barry, Andrew Nisbet, David Bradley (2012)An investigation of the thermoluminescence of Ge-doped SiO(2) optical fibres for application in interface radiation dosimetry., In: Applied Radiation and Isotopes70(7)pp. 1436-1441

    We investigate the ability of high spatial resolution (∼120μm) Ge-doped SiO(2) TL dosimeters to measure photoelectron dose enhancement resulting from the use of a moderate to high-Z target (an iodinated contrast media) irradiated by 90kVp X-rays. We imagine its application in a novel radiation synovectomy technique, modelled by a phantom containing a reservoir of I(2) molecules at the interface of which the doped silica dosimeters are located. Measurements outside of the iodine photoelectron range are provided for using a stepped-design that allows insertion of the fibres within the phantom. Monte Carlo simulation (MCNPX) is used for verification. At the phantom medium I(2)-interface additional photoelectron generation is observed, ∼60% above that in the absence of the I(2), simulations providing agreement to within 3%. Percentage depth doses measured away from the iodine contrast medium reservoir are bounded by published PDDs at 80kVp and 100kVp.

    K. Ley, S.M. Jafari, A. Lohstroh, D.A. Bradley (2019)Investigations of thermoluminescent silica beads of different manufacturers and colours, In: Radiation Physics and Chemistry155pp. 178-183 Elsevier

    Increased interest in silica based materials for use in medical thermolumiscence (TL)-based dosimetry has led to investigations of tailoring different types of technologies for specific uses. Here we study a low-cost approach to the harnessing of this emerging dosimetry technique, utilising commercially manufactured doped silica beads. The beads have been previously studied using two well-established TLD Reader systems, namely the HARSHAWand TOLEDO brands, and are now being studied making use of a RisØ TL/OSL system, a more modern and also highly sensitive facility. Characterisation studies have been conducted and results from this have been compared against that of existing literature including glow-curves and colour study TL-yield responses. The outcome confirms that colourless beads produce the highest yield when observing the 2.7 eV electron trap of silica based materials with TLD techniques. Investigations have also been made concerning the batch homogeneity of coloured beads from two different manufacturers, Mill Hill, Japan and Toho Czech, and different physical finishes of the silica beads, transparent or frosted. Studies also show that the colourless beads displaying the best batch homogeneity overall are those produced by Mill Hill Japan, measured by the percentage difference from the average TL yield, with the clear petite beads displaying the best homogeneity.

    F Issa, A Nisbet, DA Bradley, RP Hugtenburg (2013)Novel high resolution I brachytherapy source dosimetry using Ge-doped optical fibres, In: Radiation Physics and Chemistry92pp. 48-53

    The steep dose gradients close to brachytherapy sources limit the ability to obtain accurate measurements of dose. Here we use a novel high spatial resolution dosimeter to measure dose around a I source and compare against simulations. Ge-doped optical fibres, used as thermoluminescent dosimeters, offer sub-mm spatial resolution, linear response from 10cGy to >1kGy and dose-rate independence. For a I brachytherapy seed in a PMMA phantom, doses were obtained for source-dosimeter separations from 0.1cm up to several cm, supported by EGSnrc/DOSRZznrc Monte Carlo simulations and treatment planning system data. The measurements agree with simulations to within 2.3%±0.3% along the transverse and perpendicular axes and within 3.0%±0.5% for measurements investigating anisotropy in angular dose distribution. Measured and Veriseed™ brachytherapy treatment planning system (TPS) values agreed to within 2.7%±0.5%.Ge-doped optical fibre dosimeters allow detailed dose mapping around brachytherapy sources, not least in situations of high dose gradient. © 2013 Elsevier Ltd.

    Shakardokht Jafari, Nicholas Bates, T Jupp, S F Abdul Sani, Andrew Nisbet, David Bradley (2016)Commercial glass beads as TLDs in radiotherapy produced by different manufacturers, In: Radiation Physics and Chemistry137pp. pp181-186

    While commercial jewellery glass beads offer the basis of novel radiotherapy TL dosimetry (Jafari et al. 2014a,b,c, 2015a,b), detailed study of TL variation is required for the products from various manufacturers. Investigation is made for glass beads from four manufacturers from four countries: China (Rocaille), Japan (Mill Hill), Indonesia (TOHO™) and Czech Republic (Czech). Sample composition was determined using an energy-dispersive X-ray unit coupled to a scanning electron microscope. Values of mass attenuation coefficient, μ/ρ, as a function of photon energy were then calculated for photons of energy 1 keV to 10 MeV, using the National Institute of Standards and Technology XCOM program. Radiation and energy response were determined using X-rays generated at accelerating potentials from 80 kVp to 6 MV (TPR20/10¼0.670). All bead types showed TL to be linear with dose (R240.999). Glow curve dosimetric peaks reached a maximum value at 300 °C for the Toho and 290 °C for the Czech and Mill Hill products but was between 200–250 °C for the Rocaille product. Radiation sensitivity following mass normalisation varied within an order of magnitude; Toho samples showed the greatest and Rocaille the least sensitivity. For the Toho, Czech, Rocaille and Mill Hill samples the energy responses at 80 kVp were 5.0, 4.0, 3.6 and 3.3 times that obtained at 6 MV. All four glass bead types offer potential use as TL dosimeters over doses commonly applied in radiotherapy. Energy response variation was o1% at 6 MV but significant variation was found for photon beam energies covering the kV range; careful characterisation is required if use at this range is intended.

    E Daar, W Kaabar, C Lei, JL Keddie, A Nisbet, DA Bradley (2010)AFM and uni-axial testing of pericardium exposed to radiotherapy doses, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment652(1)pp. 874-877 Elsevier
    AS Habib, AL Shutt, PH Regan, MC Matthews, H Alsulaiti, DA Bradley (2014)Characterization of naturally occurring radioactive materials in Libyan oil pipe scale using a germanium detector and Monte Carlo simulation, In: RADIATION PHYSICS AND CHEMISTRY95pp. 352-355 PERGAMON-ELSEVIER SCIENCE LTD
    H Al-Sulaiti, T Nasir, KS Al Mugren, N Alkhomashi, N Al-Dahan, M Al-Dosari, DA Bradley, S Bukhari, M Matthews, PH Regan, T Santawamaitre, D Malain, A Habib (2012)Determination of the natural radioactivity levels in north west of Dukhan, Qatar using high-resolution gamma-ray spectrometry., In: Appl Radiat Isot70(7)pp. 1344-1350

    This study is aimed at the determination of the activity concentrations of naturally occuring and technologically enhanced levels of radiation in 34 representative soil samples that have been collected from an inshore oil field area which was found to have, in a previous study, the highest observed value of 226Ra concentration among 129 soil samples. The activity concentrations of 238U and 226Ra have been inferred from gamma-ray transitions associated with their decay progenies and measured using a hyper-pure germanium detector. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented, together with the values of the activity concentrations associated with the naturally occuring radionuclide chains for all the samples collected from NW Dukhan. Discrete-line, gamma-ray energy transitions from spectral lines ranging in energy from ∼100 keV up to 2.6 MeV have been associated with characteristic decays of the various decay products within the 235.8U and 232Th radioactive decay chains. These data have been analyzed, under the assumption of secular equilibrium for the U and Th decay chains. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented. The weighted mean value of the activity concentrations of 226Ra in one of the samples was found to be around a factor of 2 higher than the values obtained in the previous study and approximately a factor of 10 higher than the accepted worldwide average value of 35 Bq/kg. The weighted mean values of the activity concentrations of 232Th and 40K were also deduced and found to be within the worldwide average values of 30 and 400 Bq/kg, respectively. Our previous study reported a value of 201.9±1.5Stat.±13Syst.Bq/kg for 226Ra in one sample and further investigation in the current work determined a measured value for 226Ra of 342.00±1.9Stat.±25Syst.Bq/kg in a sample taken from the same locality. This is significantly higher than all the other investigated soil samples in the current and previous works. Notably, the Th levels in the same sample are within the worldwide average expectations, implying that the increased 226Ra concentration arises from TENORM processes.

    NH Yaakob, H Wagiran, M Imam Hossain, AT Ramli, DA Bradley, H Ali (2011)Low-dose photon irradiation response of Ge and Al-doped SiO2 optical fibres, In: Applied Radiation and Isotopes69(9)pp. 1189-1192 Elsevier
    YM Amin, RH Mahat, RM Nor, MU Khandaker, GH Takleef, DA Bradley (2013)The presence of natural radioactivity and 137Cs in the South China Sea bordering peninsular Malaysia., In: Radiat Prot Dosimetry156(4)pp. 475-480

    The presence of natural radioactivity and (137)Cs has been investigated in fresh media obtained from South China Sea locations off the coast of peninsular Malaysia. The media include seafood, sea water and sediment. The samples were collected some weeks prior to the devastating 2011 Tōhoku earthquake and associated tsunami, the occurrence of which precipitated the Fukushima incident. All samples showed the presence of naturally occurring (226)Ra, (228)Ra and primordial (40)K, all at typically prevailing levels. The concentrations of natural radioactivity in molluscs were found to be greater than that of other marine life studied herein, the total activity ranging from 337 to 393 Bq kg(-1) dry weight. The total activity in sea water ranged from 15 to 88 Bq l(-1). Sediment samples obtained at deep sea locations more than 20 km offshore further revealed the presence of (137)Cs. The activity of (137)Cs varied from ND to 0.5 Bq kg(-1) dry weight, the activity increasing with offshore distance and depth. The activity concentrations presented herein should be considered useful in assessing the impact of any future radiological contamination to the marine environment.

    NM Noor, M Hussein, DA Bradley, A Nisbet, T Kadni (2014)Characterization of Ge-doped optical fibres for MV radiotherapy dosimetry, In: Radiation Physics and Chemistry98pp. 33-41

    Ge-doped optical fibres offer promising thermoluminescence (TL) properties together with small physical size and modest cost. Their use as dosimeters for postal radiotherapy dose audits of megavoltage photon beams has been investigated. Key dosimetric characteristics including reproducibility, linearity, dose rate, temperature and angular dependence have been established. A methodology of measuring absorbed dose under reference conditions was developed. The Ge-doped optical fibres offer linearity between TL yield and dose, with a reproducibility of better than 5%, following repeated measurements (n=5) for doses from 5cGy to 1000cGy. The fibres also offer dose rate, angular and temperature independence, while an energy-dependent response of 7% was found over the energy range 6MV to 15MV (TPR of 0.660, 0.723 and 0.774 for 6, 10 and 15MV respectively). The audit methodology has been developed with an expanded uncertainty of 4.22% at 95% confidence interval for the photon beams studied. © 2013 Elsevier Ltd.

    P Muthuvelu, RE Ellis, EM Green, D Attenburrow, R Barrett, K Arkill, DB Colridge, CP Winlove, DA Bradley (2007)Microvascularity, blood flow and tissue structure at the subchondral plate using an X-ray fluorescence technique, In: JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY271(3)pp. 771-775 SPRINGER
    MU Khandaker, K Asaduzzaman, SM Nawi, AR Usman, YM Amin, E Daar, DA Bradley, H Ahmed, AA Okhunov (2015)Assessment of Radiation and Heavy Metals Risk due to the Dietary Intake of Marine Fishes (Rastrelliger kanagurta) from the Straits of Malacca, In: PLOS ONE10(6)ARTN epp. ?-? PUBLIC LIBRARY SCIENCE
    NNH Ramli, H Salleh, GA Mahdiraji, MI Zulkifli, S Hashim, DA Bradley, NM Noor (2015)Characterization of amorphous thermoluminescence dosimeters for patient dose measurement in X-ray diagnostic procedures, In: RADIATION PHYSICS AND CHEMISTRY116pp. 130-134 PERGAMON-ELSEVIER SCIENCE LTD
    SM Jafari, TJ Jordan, M Hussein, David Bradley, CH Clark, Andrew Nisbet, NM Spyrou (2014)Energy response of glass bead TLDs irradiated with radiation therapy beams, In: RADIATION PHYSICS AND CHEMISTRY104pp. 208-211 PERGAMON-ELSEVIER SCIENCE LTD

    Glass beads are a novel TL dosimeter in radiotherapy. An important characteristic of TL dosimeters is their energy response, especially when intended for use in radiotherapy applications over a wide range of energies (typically from X-rays generated at 80 kVp up to 25 MV photon and MeV electron beams). In this paper, the energy response of glass beads (Mill Hill, Japan) is investigated for their TL response to kV X-rays from an orthovoltage radiotherapy unit and also for MV photon and MeV electron beams from a medical linear accelerator. The experimental findings show that for photon and electron beams, the TL response of this particular glass bead, normalised to unity for 6 MV X-rays (TPR20/10¼0.670), decreases to 0.9670.02 for 15 MV X-rays (TPR20/10¼0.761) and to 0.9570.01 for 20 MeV electron beams (R50,D¼8.35 cm). This compares favourably with other TLD materials such as LiF and also alanine dosimeters that are readout with an EPR system. For kV X-rays, the response increases to 4.5270.05 for 80 kV X-rays (HVL¼2.4 mm Al) which approaches 3 times that of LiF TLDs and 5 times that of alanine. In conclusion, the particular glass beads, when used as a dosimeter material, show a relatively small energy dependence over the megavoltage range of clinically relevant radiation qualities, being clearly advantageous for accurate dosimetry. Conversely, the energy response is significant for photon beam energies covering the kV range. In both circumstances, in dosimetric evaluations the energy response needs to be taken into account.

    T Santawamaitre, D Malain, HA Al-Sulaiti, M Matthews, DA Bradley, PH Regan (2011)Study of natural radioactivity in riverbank soils along the Chao Phraya river basin in Thailand, In: SORMA XII 2010: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment652(1)pp. 920-924 Elsevier
    E Daar, W Kaabar, A Nisbet, DA Bradley, E Woods, C Lei (2014)Atomic force microscopy and mechanical testing of bovine pericardium irradiated to radiotherapy doses, In: Radiation Physics and Chemistry96pp. 176-180

    Within the context of radiotherapy our work investigates the feasibility of identifying changes in structural and biomechanical properties of pericardium resulting from exposure to penetrating photon irradiation. Collagen fibres extracted from bovine pericardium were chosen as a model of pericardium extracellular matrix as these form the main fibrous component of the medium. Tests of mechanical properties, controlled by the various structural elements of the tissues, were performed on frontal pericardium, including uni-axial tests and atomic force microscopy (AFM). While the irradiated collagen fibres showed no significant change in D-band spacing up to doses of 80. Gy, the fibre width was found to increase by 34±9% at 80. Gy when compared with that for un-irradiated samples. © 2013 Elsevier Ltd.

    E Dermosesian, GA Mahdiraji, FRM Adikan, DA Bradley (2015)Improving thermoluminescence response through the fabrication of novel microstructured fibers, In: RADIATION PHYSICS AND CHEMISTRY116pp. 135-137 PERGAMON-ELSEVIER SCIENCE LTD
    G.W. Grime, S.F. Abdul Sani, Vladimir Palitsin, A.S. Siti Shafiqah, M.J. Maah, Amjad Alyahyawi, D.A. Bradley (2019)Simultaneous microbeam IBA and beam-induced luminescence analysis of strained doped silica fibre radiation dosimeters, In: Radiation Physics and Chemistry155pp. 173-177 Elsevier

    We demonstrate that the simultaneous combination of ion beam analysis (IBA) and ion beam induced luminescence (IL) can reveal valuable information concerning the performance of strained doped silica fibre thermoluminescence microdosimeters. The micron scale spatial resolution and low detection limits of IBA allow the lateral distribution of dopant elements to be mapped and then correlated with the distribution of prompt radioluminescence. Measurement of the decay of the IL signal with dose provide information concerning the saturation of the subsequent TL signal at high doses. MeV ion beams can deposit relatively high energy in localized, well-quantified small volumes and so this method is valuable for studying high dose effects in TL dosimeters. We describe a simple modification of the target chamber microscope which enables sensitive low background light detection in two wavelength bands and present preliminary results from three types of germanium doped silica fibre dosimeter.

    J Loveland, O Gundogdu, E Morton, K Wells, DA Bradley (2010)Phase contrast imaging: Effect of increased object-detector distances at X-ray diagnostic and megavoltage energies, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment652(1)pp. 625-629 Elsevier
    Niki Bardi, Izabela Jurewicz, AK King, Mohammed Alkhorayef, David Bradley, Alan Dalton (2017)X-ray irradiation-induced structural changes on Single Wall Carbon Nanotubes, In: Radiation Physics and Chemistry140pp. 34-37 Elsevier

    Dosimetry devices based on Carbon Nanotubes are a promising new technology. In particular using devices based on single wall carbon nanotubes may offer a tissue equivalent response with the possibility for device miniaturisation, high scale manufacturing and low cost. An important precursor to device fabrication requires a quantitative study of the effects of X-ray radiation on the physical and chemical properties of the individual nanotubes. In this study, we concentrate on the effects of relatively low doses, 20 cGy and 45 cGy, respectively. We use a range of characterization techniques including scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy to quantify the effects of the radiation dose on inherent properties of the nanotubes. Specifically we find that the radiation exposure results in a reduction in the sp2 nature of the nanotube bond structure. Moreover, our analysis indicates that the exposure results in nanotubes that have an increased defect density which ultimately effects the electrical properties of the nanotubes.

    AD Bajoga, N Alazemi, H Shams, Patrick Regan, David Bradley (2016)Evaluation of naturally occurring radioactivity across the State of Kuwait using high-resolution gamma-ray spectrometry, In: Radiation Physics and Chemistry137pp. 203-209 Elsevier

    A study of natural radioactivity from 90 different soil samples from the state of Kuwait has been carried out to ascertain the NORM concentration values across the country. The calculated activity concentrations were determined from: (i) the decays of the 226Ra, 214Pb and 214Bi members of the 4n+2 decay chain headed by 238U and; (ii) the 228Ac, 212Pb and 208Tl members of the 4n chain headed by 232Th. The study also included evaluations for the 235U decay chain with the 186 keV doublet transition used together with the measured 4n+2 activity concentration values to determine the 235U/238U isotopic ratios for each sample. The values for the arithmetic mean activity concentrations for 90 separate locations across Kuwait as determined in the current work were 17.2, 14.1, and 368 Bq/kg, with standard deviations of 5.2, 3.7 and 90 Bq/kg for the 238U, 232Th and 40K activity concentrations respectively. Measured isotope ratios for 235U/238U give an arithmetic mean value for all of the samples of 0.045±0.003, consistent with that expected for natural uranium. These results indicate no evidence for a radiologically significant dispersion of additional depleted uranium across the entire State of Kuwait from the 1991 Gulf War.

    AKMM Rahman, HT Zubair, M Begum, HA Abdul-Rashid, Z Yusoff, NM Ung, KA Mat-Sharif, WSW Abdullah, GA Mahdiraji, YM Amin, MJ Maah, DA Bradley (2015)Germanium-doped optical fiber for real-time radiation dosimetry, In: RADIATION PHYSICS AND CHEMISTRY116pp. 170-175 PERGAMON-ELSEVIER SCIENCE LTD
    EC Ismail, W Kaabar, D Garrity, O Gundogdu, O Bunk, F Pfeiffer, MJ Farquharson, DA Bradley (2010)X-ray phase contrast imaging of the bone-cartilage interface, In: APPLIED RADIATION AND ISOTOPES68(4-5)pp. 767-771 PERGAMON-ELSEVIER SCIENCE LTD
    Amjad Alyahyawi, A. Dimitriadis, S.M. Jafari, A. Lohstroh, A. Alanazi, A. Alsubaie, C.H. Clark, A. Nisbet, D.A. Bradley (2019)Thermoluminescence measurements of eye-lens dose in a multi-centre stereotactic radiosurgery audit, In: Radiation Physics and Chemistry155pp. 75-81 Elsevier

    Stereotactic radiosurgery (SRS), a non-invasive therapeutic technique, seeks delivery of elevated doses of ionizing radiation to precisely defined targets while at the same time preserving surrounding tissue viability. SRS was developed for treatment of various functional abnormalities, extending also to benign and malignant lesions (the latter sometimes referred to as stereotactic body radiation therapy, SBRT). Local tumour control for single and multiple brain metastases at low complication rates is one such outcome. Notable commercial SRS platforms include Gamma Knife and the linac-based systems, Novalis and Cyberknife. Such systems use imaging techniques that include computed tomography (CT) and magnetic resonance imaging (MRI) in localizing SRS targets, down to a small fraction of one mm. With a wide range of platforms for delivery of SRS, greater investigation and standardization is called for. Present work concerns a multi-centre dosimetric audit (20 centres in all), investigating the range of SRS machines and techniques for a single brain metastasis using a series of small dimension detectors (1.55 mm and less) and an anthropomorphic head phantom. With the lens as one of the more radiosensitive tissues, the aim has been to determine the scattered radiation lens dose received during an SRS treatment, as well as the imaging dose received during planning-stage CT-scanning. Custom-designed holders were fabricated to carry three types of thermoluminescence dosimeters: Ge-doped silica fibres, silica glass beads and TLD-100, the latter as a reference dosimeter (being also of larger dimension than the silica-based dosimeters). For reproducible placement of the TLD holders, a bespoke 3D-printed goggle insert was produced for the head phantom. International guidance is to seek reduction in lens dose down to 0.5 Gy. Present results show lens dose values below 0.5 Gy, albeit sometimes to modest degree, there being need to continue to exercise associated due care in SRS planning and delivery.

    F Issa, NAA Latip, DA Bradley, A Nisbet (2010)Ge-doped optical fibres as thermoluminescence dosimeters for kilovoltage X-ray therapy irradiations, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment652(1)pp. 834-837 Elsevier
    David Bradley, A S Siti Shafiqah, Z Siti Rozaila, S N Sabtu, S F Abdul Sani, A H Alanazi, Shakardokht Jafari, G Amouzad Mahdiraji, F R Mahamd Adikan, M J Maah, Andrew Nisbet, N Tamchek, H A Abdul Rashid, M Alkhorayef, K Alzimami (2016)Developments in production of silica-based thermoluminescence dosimeters, In: Radiation Physics and Chemistry137pp. 37-44

    This work addresses purpose-made thermoluminescence dosimeters (TLD) based on doped silica fibres and sol–gel nanoparticles, produced via Modified Chemical Vapour Deposition (MCVD) and wet chemistry techniques respectively. These seek to improve upon the versatility offered by conventional phosphor-based TLD forms such as that of doped LiF. Fabrication and irradiation-dependent factors are seen to produce defects of differing origin, influencing the luminescence of the media. In coming to a close, we illustrate the utility of Ge-doped silica media for ionizing radiation dosimetry, first showing results from gamma-irradiated Ag-decorated nanoparticles, in the particular instance pointing to an extended dynamic range of dose. For the fibres, at radiotherapy dose levels, we show high spatial resolution (0.1 mm) depth-dose results for proton irradiations. For novel microstructured fibres (photonic crystal fibres, PCFs) we show first results from a study of undisturbed and technologically modified naturally occurring radioactivity environments, measuring doses of some 10 s of μGy over a period of several months.

    A Alanazi, M Alkhorayef, K Alzimami, I Jurewicz, N Abuhadi, A Dalton, DA Bradley (2016)Carbon nanotubes buckypaper radiation studies for medical physics applications., In: Appl Radiat Isot

    Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In such circumstance, dosimeters with atomic number similar to human tissue are needed. Carbon nanotubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nanotubes (SWCNTs) buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2Gy. This finding suggests that carbon nanotubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance.

    H Al-Sulaiti, N Alkhomashi, N Al-Dahan, M Al-Dosari, DA Bradley, S Bukhari, M Matthews, PH Regan, T Santawamaitre (2011)Determination of the natural radioactivity in Qatarian building materials using high-resolution gamma-ray spectrometry, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment652(1)pp. 915-919 Elsevier
    DA Bradley, SM Jafari, AS Siti Shafiqah, N Tamcheck, A Shutt, Z Siti Rozaila, SF Abdul Sani, SN Sabtu, A Alanazi, G Amouzad Mahdiraji, HA Abdul Rashid, MJ Maah (2015)Latest developments in silica-based thermoluminescence spectrometry and dosimetry., In: Appl Radiat Isot

    Using irradiated doped-silica preforms from which fibres for thermoluminescence dosimetry applications can be fabricated we have carried out a range of luminescence studies, the TL yield of the fibre systems offering many advantages over conventional passive dosimetry types. In this paper we investigate such media, showing emission spectra for irradiated preforms and the TL response of glass beads following irradiation to an (241)Am-Be neutron source located in a tank of water, the glass fibres and beads offering the advantage of being able to be placed directly into liquid. The outcomes from these and other lines of research are intended to inform development of doped silica radiation dosimeters of versatile utility, extending from environmental evaluations through to clinical and industrial applications.

    S Saeed Al-Ahbabi, DA Bradley, M Beyomi, Z Alkatib, S Adhaheri, M Darmaki, A Nisbet (2012)A comparison of protocols for external beam radiotherapy beam calibrations., In: Appl Radiat Isot70(7)pp. 1331-1336

    A number of codes of practice (CoP) for electron and photon radiotherapy beam dosimetry are currently in use. Comparison is made of the more widely used of these, specifically those of the International Atomic Energy Agency (IAEA TRS-398), the American Association of Physicists in Medicine (AAPM TG-51) and the Institute of Physics and Engineering in Medicine (IPEM 2003). All are based on calibration of ionization chambers in terms of absorbed dose to water, each seeking to reduce uncertainty in delivered dose, providing an even stronger system of primary standards than previous air-kerma based approaches. They also provide a firm, traceable and straight-forward formalism (Radiology, 1996). Included in making dose assessments for the three CoP are calibration coefficients for a range of beam quality indices. Measurements have been performed using clinical photon and electron beams, the absorbed dose to water being obtained following the recommendations given by each code. Electron beam comparisons have been carried out using measurements for electron beams of nominal energies 6, 9, 12, 16 and 20 MeV. Comparisons were also carried out for photon beams of nominal energies 6 and 18 MV. For photon beams use was made of NE2571 cylindrical graphite walled ionization chambers, cross-calibrated against an NE2611 Secondary Standard; for electron beams, PTW Markus and NACP-02 plane-parallel chambers were used. Irradiations were made using Varian 600C/2100C linacs, supported by water tanks and Virtual Water™ phantoms. The absorbed doses for photon and electron beams obtained following these CoP are all in good agreement, with deviations of less than 2%. A number of studies have been carried out by different groups in different countries to examine the consistency of dosimetry codes of practice or protocols. The aim of these studies is to confirm that the goal of those codes is met, namely uniformity in establishment of dosimetry of all radiation beam types used in cancer therapy in the world, and this is one of the studies.

    MSA Fadzil, NNH Ramli, MA Jusoh, T Kadni, DA Bradley, NM Ung, H Suhairul, NM Noor (2014)Dosimetric characteristics of fabricated silica fibre for postal radiotherapy dose audits, In: HM Zin, ATA Rahman, NA Kadri, R Zainon (eds.), 9TH NATIONAL SEMINAR ON MEDICAL PHYSICS (NSMP2014)546ARTN 01201 IOP PUBLISHING LTD
    SFA Sani, GW Grime, V Palitsin, GA Mahdiraji, HAA Rashid, MJ Maah, DA Bradley (2015)Micro-PIXE analysis of doped SiO2 fibres intended as TL dosimeters for radiation measurements, In: X-RAY SPECTROMETRY44(2)pp. 33-40 WILEY-BLACKWELL
    A Alawiah, MS Alina, S Bauk, HA Abdul-Rashid, W Gieszczyk, MN Noramaliza, GA Mandiraji, N Tamchek, MI Zulkifli, DA Bradley, MW Marashdeh (2015)The thermoluminescence characteristics and the glow curves of Thulium doped silica fiber exposed to 10 MV photon and 21 MeV electron radiation, In: APPLIED RADIATION AND ISOTOPES98pp. 80-86 PERGAMON-ELSEVIER SCIENCE LTD
    DA Bradley, S Hashim, MI Saripan, K Wells, WL Dunn (2011)Photon signature analysis using template matching, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment652(1)pp. 466-469 Elsevier
    SM Alkhateeb, MH Abdelkader, DA Bradley, P Seller, MC Veale, MD Wilson, S Pani, RM Nishikawa, BR Whiting, C Hoeschen (2013)Energy dispersive X-ray diffraction computed tomography of breast-simulating phantoms and a tissue sample, In: MEDICAL IMAGING 2013: PHYSICS OF MEDICAL IMAGING8668ARTN 8pp. ?-? SPIE-INT SOC OPTICAL ENGINEERING
    SF Abdul Sani, AI Alalawi, Andrew Nisbet, David Bradley, H Azhar A R, G Amouzad Mahdiraji, N Tamchek, MJ Maah (2014)High sensitivity flat SiO fibres for medical dosimetry, In: Radiation Physics and Chemistry104pp. 134-138

    We describe investigation of a novel undoped flat fibre fabricated for medical radiation dosimetry. Using high energy X-ray beams generated at a potential of 6MV, comparison has been made of the TL yield of silica flat fibres, TLD-100 chips and Ge-doped silica fibres. The flat fibres provide competitive TL yield to that of TLD-100 chips, being some 100 times that of the Ge-doped fibres. Pt-coated flat fibres have then been used to increase photoelectron production and hence local dose deposition, obtaining significant increase in dose sensitivity over that of undoped flat fibres. Using 250kVp X-ray beams, the TL yield reveals a progressive linear increase in dose for Pt thicknesses from 20nm up to 80nm. The dose enhancement factor (DEF) of (0.0150±0.0003)nm Pt is comparable to that obtained using gold, agreeing at the 1% level with the value expected on the basis of photoelectron generation. Finally, X-ray photoelectron spectroscopy (XPS) has been employed to characterize the surface oxidation state of the fibre medium. The charge state of Si2p was found to lie on 103.86eV of binding energy and the atomic percentage obtained from the XPS analysis is 22.41%. © 2014 Elsevier Ltd.

    YM Abubakar, Matthew Taggart, Abdullah Alsubaie, Abdulaziz Alanazi, Amjad Alyahyawi, Annika Lohstroh, A Shutt, Shakardokht Jafari, David Bradley (2016)Characterisation of an isotropic neutron source: a comparison of conventional neutron detectors and micro-silica glass bead thermoluminescent detectors, In: Radiation Physics and Chemistry140pp. 497-501 Elsevier

    As a result of their thermoluminescent response, low cost commercial glass beads have been demonstrated to offer potential use as radiation dosimeters, providing capability in sensing different types of ionising radiation. With a linear response over a large range of dose and spatial resolution that allows measurements down to the order of 1 mm, their performance renders them of interest in situations in which sensitivity, dynamic range, and fine spatial resolution are called for. In the present work, the suitability of glass beads for characterisation of an AmericiumBeryllium (241AmBe) neutron source has been assessed. Direct comparison has been made using conventional 3He and boron tri-fluoride neutron detectors as well as Monte Carlo simulation. Good agreement is obtained between the glass beads and gas detectors in terms of general reduction of count rate with distance. Furthermore, the glass beads demonstrate exceptional spatial resolution, leading to the observation of fine detail in the plot of dose versus distance from source. Fine resolution peaks arising in the measured plots, also present in simulations, are interesting features which based on our best knowledge have previously not been reported. The features are reproduced in both experiment and simulation but we do not have a firm reason for their origin. Of greater clarity is that the glass beads have considerable potential for use in high spatial resolution neutron field characterisation, subject to the availability of a suitable automated TLD reader.

    O Gundogdu, E Nirgianaki, EC Ismail, PM Jenneson, DA Bradley (2007)Benchtop phase-contrast X-ray imaging, In: APPLIED RADIATION AND ISOTOPES65(12)pp. 1337-1344 PERGAMON-ELSEVIER SCIENCE LTD
    AL Palmer, A Nisbet, D Bradley (2013)Verification of high dose rate brachytherapy dose distributions with EBT3 Gafchromic film quality control techniques, In: PHYSICS IN MEDICINE AND BIOLOGY58(3)pp. 497-511 IOP PUBLISHING LTD
    S Hashim, SSC Omar, SA Ibrahim, WMSW Hassan, NM Ung, GA Mandiraji, DA Bradley, K Alzimami (2015)Thermoluminescence response of flat optical fiber subjected to 9 MeV electron irradiations, In: RADIATION PHYSICS AND CHEMISTRY106pp. 46-49 PERGAMON-ELSEVIER SCIENCE LTD
    OD Gonçalves, DA Bradley (2013)ISRP-12: The 12th International Symposium on Radiation Physics, In: Radiation Physics and Chemistry
    MU Khandaker, NB Wahib, YM Amin, DA Bradley (2013)Committed effective dose from naturally occuring radionuclides in shellfish, In: RADIATION PHYSICS AND CHEMISTRY88pp. 1-6 PERGAMON-ELSEVIER SCIENCE LTD
    YSM Alajerami, S Hashim, SK Ghoshal, DA Bradley, M Mhareb, MA Saleh (2014)Copper doped borate dosimeters revisited, In: JOURNAL OF LUMINESCENCE155pp. 141-148 ELSEVIER SCIENCE BV
    SFA Sani, GA Mahdiraji, ASS Shafiqah, GW Grime, V Palitsin, SJ Hinder, N Tamchek, HAA Rashid, MJ Maah, JF Watts, DA Bradley (2015)XPS and PIXE Analysis of Doped Silica Fibre for Radiation Dosimetry, In: JOURNAL OF LIGHTWAVE TECHNOLOGY33(11)pp. 2268-2278 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    A Alawiah, S Bauk, MW Marashdeh, MZN Nazura, HA Abdul-Rashid, Z Yusoff, W Gieszczyk, MN Noramaliza, FRM Adikan, GA Mandiraji, N Tamchek, SZ Muhd-Yassin, KA Mat-Sharif, MI Zulkifli, N Omar, WSW Abdullah, DA Bradley (2015)The thermoluminescence glow curve and the deconvoluted glow peak characteristics of erbium doped silica fiber exposed to 70-130 kVp x-rays, In: APPLIED RADIATION AND ISOTOPES104pp. 197-202 PERGAMON-ELSEVIER SCIENCE LTD
    W Kaabar, O Gundogdu, A Laklouk, O Bunk, F Pfeiffer, MJ Farquharson, DA Bradley (2010)mu-PIXE and SAXS studies at the bone-cartilage interface, In: APPLIED RADIATION AND ISOTOPES68(4-5)pp. 730-734 PERGAMON-ELSEVIER SCIENCE LTD

    BACKGROUND: Detection of buried improvised explosive devices (IEDs) is a delicate task, leading to a need to develop sensitive stand-off detection technology. The shape, composition and size of the IEDs can be expected to be revised over time in an effort to overcome increasingly sophisticated detection methods. As an example, for the most part, landmines are found through metal detection which has led to increasing use of non-ferrous materials such as wood or plastic containers for chemical based explosives being developed. METHODOLOGY: Monte Carlo simulations have been undertaken considering three different commercially available detector materials (hyperpure-Ge (HPGe), lanthanum(III) bromide (LaBr) and thallium activated sodium iodide (NaI(Tl)), applied at a stand-off distance of 50 cm from the surface and burial depths of 0, 5 and 10 cm, with sand as the obfuscating medium. Target materials representing medium density wood and mild steel have been considered. Each detector has been modelled as a 10 cm thick cylinder with a 20 cm diameter. PRINCIPAL FINDINGS: It appears that HPGe represents the most promising detector for this application. Although it was not the highest density material studied, its excellent energy resolving capability leads to the highest quality spectra from which detection decisions can be inferred. CONCLUSIONS: The simulation work undertaken here suggests that a vehicle-born threat detection system could be envisaged using a single betatron and a series of detectors operating in parallel observing the space directly in front of the vehicle path. Furthermore, results show that non-ferrous materials such as wood can be effectively discerned in such remote-operated detection system, with the potential to apply a signature analysis template matching technique for real-time analysis of such data.

    A Alawiah, S Bauk, HA Abdul-Rashid, W Gieszczyk, S Hashim, GA Mandiraji, N Tamchek, DA Bradley (2015)Potential application of pure silica optical flat fibers for radiation therapy dosimetry, In: RADIATION PHYSICS AND CHEMISTRY106pp. 73-76 PERGAMON-ELSEVIER SCIENCE LTD
    N Wahib, NN Zulkepely, SNM Nawi, YM Amin, YS Ling, SFA Sani, MJ Maah, DA Bradley (2015)Gamma irradiated thermoluminescence response of Ge-doped SiO2 fibre, In: APPLIED RADIATION AND ISOTOPES105pp. 158-162 PERGAMON-ELSEVIER SCIENCE LTD
    W Kaabar, E Daar, O Bunk, MJ Farquharson, A Laklouk, C Jeynes, M Bailey, O Gundogdu, DA Bradley (2011)Elemental and structural studies at the bonecartilage interface, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment652(1)pp. 786-790
    SA Choulis, Y. Kim, J Nelson, D D Bradley, M Giles, M Shkunov, I McCulloch (2004)High Ambipolar and Balanced Carrier Mobility in Regioregular Poly(3-hexylthiophene), In: Applied Physics Letters85(17) AIP Publishing

    The carrier transport of carefully purified regioregular poly(3-hexylthiophene) films was studied using time-of-flight photocurrent measurements. The authors find balanced ambipolar transport with a room-temp. mobility for holes of 3 * 10-4 cm2 V-1 s-1 and for electrons of 1.5 * 10-4 cm2 V-1 s-1 at elec. fields >=105 V/cm. The transport is relatively field independent and weakly temp. dependent, pointing to a high degree of chem. regioregularity and purity. These factors make poly(3-hexylthiophene) attractive for use in a range of electronic applications.

    P Kamali-Zonouzi, A Shutt, Andrew Nisbet, David Bradley (2017)Feasibility of employing thick microbeams from superficial and orthovoltage kVp x-ray tubes for radiotherapy of superficial cancers, In: Radiation Physics and Chemistry140pp. 237-241 Elsevier

    Preclinical investigations of thick microbeams show these to be feasible for use in radiotherapeutic dose delivery. To create the beams we access a radiotherapy x-ray tube that is familiarly used within a conventional clinical environment, coupling this with beam-defining grids. Beam characterisation, both single and in the form of arrays, has been by use of both MCNP simulation and direct Gafchromic EBT film dosimetry. As a first step in defining optimal exit-beam profiles over a range of beam energies, simulation has been made of the x-ray tube and numbers of beam-defining parallel geometry grids, the latter being made to vary in thickness, slit separation and material composition. For a grid positioned after the treatment applicator, and of similar design to those used in the first part of the study, MCNP simulation and Gafchromic EBT film were then applied in examining the resultant radiation profiles. MCNP simulations and direct dosimetry both show useful thick microbeams to be produced from the x-ray tube, with peak-to-valley dose ratios (PVDRs) in the approximate range 8.8–13.9. Although the potential to create thick microbeams using radiotherapy x-ray tubes and a grid has been demonstrated, Microbeam Radiation Therapy (MRT) would still need to be approved outside of the preclinical setting, a viable treatment technique of clinical interest needing to benefit for instance from substantially improved x-ray tube dose rates.

    NM Noor, M Hussein, DA Bradley, A Nisbet (2011)Investigation of the use of Ge-doped optical fibre for in vitro IMRT prostate dosimetry, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment652(1)pp. 819-823 Elsevier
    NA Zahaimi, MHRO Abdullah, H Zin, ALA Rahman, S Hashim, MI Saripan, MC Paul, DA Bradley, ATA Rahman (2014)Dopant concentration and thermoluminescence (TL) properties of tailor-made Ge-doped SiO2 fibres, In: RADIATION PHYSICS AND CHEMISTRY104pp. 297-301 PERGAMON-ELSEVIER SCIENCE LTD
    YSM Alajerami, S Hashim, SK Ghoshal, AT Ramli, MA Saleh, Z Ibrahim, T Kadni, DA Bradley (2013)Luminescence characteristics of Li2CO3-K2CO3-H3BO3 glasses co-doped with TiO2/MgO, In: APPLIED RADIATION AND ISOTOPES82pp. 12-19 PERGAMON-ELSEVIER SCIENCE LTD
    ASS Shafiqah, YM Amin, RM Nor, DA Bradley (2015)Effect of particle size on the thermoluminescence (TL) response of silica nanoparticles, In: RADIATION PHYSICS AND CHEMISTRY117pp. 102-107 PERGAMON-ELSEVIER SCIENCE LTD
    F Issa, AT Abdul Rahman, RP Hugtenburg, David Bradley, Andrew Nisbet (2012)Establishment of Ge-doped optical fibres as thermoluminescence dosimeters for brachytherapy, In: Applied Radiation and Isotopes70(7)pp. 1158-1161 Elsevier

    This study aims to establish the sensitive, ~120μm high spatial resolution, high dynamic range Ge-doped optical fibres as thermoluminescence (TL) dosimeters for brachytherapy dose distribution. This requires investigation to accommodate sensitivity of detection, both for the possibility of short range dose deposition from beta components as well as gamma/x-mediated dose. In-air measurements are made at distances close to radionuclide sources, evaluating the fall off in dose along the transverse axis of Ba and Co radioactive sources, at distances from 2mm up to 20mm from their midpoints. Measurements have been compared with Monte Carlo code DOSRZnrc simulations for photon-mediated dose only, agreement being obtained to within 3% and 1% for the Ba and Co sources, respectively. As such, in both cases it is determined that as intended, beta dose has been filtered out by source encapsulation. © 2012 Elsevier Ltd.

    KH Al-Hinai, NB Mohd, NR Zulkepely, RM Nor, YM Amin, DA Bradley (2013)A search for novel thermoluminescent radiation dosimeter media, In: APPLIED RADIATION AND ISOTOPES82pp. 126-129 PERGAMON-ELSEVIER SCIENCE LTD
    EZ Dalah, A Nisbet, S Reise, D Bradley (2008)Evaluating commercial image registration packages for radiotherapy treatment planning, In: APPLIED RADIATION AND ISOTOPES66(12)pp. 1948-1953 PERGAMON-ELSEVIER SCIENCE LTD
    S Hashim, YSM Alajerami, SK Ghoshal, MA Saleh, MI Saripan, ABA Kadir, DA Bradley, K Alzimami (2014)Dosimetric characteristics of LKB:Cu,P solid TL detector, In: RADIATION PHYSICS AND CHEMISTRY104pp. 36-39 PERGAMON-ELSEVIER SCIENCE LTD
    U Akar Tarim, O Gurler, EN Ozmutlu, S Yalcin, O Gundogdu, JM Sharaf, DA Bradley (2012)The energy spectrum of 662 keV photons in a water equivalent phantom, In: Radiation Physics and Chemistry81(7)pp. 745-748 Elsevier

    Investigation is made on the energy spectrum of photons originating from interactions of 662 keV primary gamma-ray photons emitted by a point source positioned at the centre of a water equivalent solid phantom of dimensions 19 cm×19 cm×24 cm. Peaks resulting from total energy loss (photopeak) and multiple and back scattering have been observed using a 51 mm×51 mm NaI(Tl) detector; good agreement being found between the measured and simulated response functions. The energy spectrum of the gamma photons obtained through the Monte Carlo simulation reveals local maxima at about 100 keV and 210 keV, being also observed in the experimental response function. Such spectra can be used as a method of testing the water equivalence of solid phantom media before their use for dosimetry measurements.

    NN Zulkepely, YM Amin, RM Nor, DA Bradley, MJ Maah, SNM Nawi, NF Wahib (2015)Preliminary results on the photo-transferred thermoluminescence from Ge-doped SiO2 optical fiber, In: RADIATION PHYSICS AND CHEMISTRY117pp. 108-111 PERGAMON-ELSEVIER SCIENCE LTD
    AT Abdul Rahman, A Nisbet, DA Bradley (2011)Dose-rate and the reciprocity law: TL response of Ge-doped SiO2 optical fibers at therapeutic radiation doses, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment652(1)pp. 891-895
    SNBM Nawi, NFB Wahib, NNB Zulkepely, YBM Amin, UN Min, DA Bradley, RBM Nor, MJ Maah (2015)The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation, In: SENSORS15(8)pp. 20557-20569 MDPI AG
    YSM Alajerami, S Hashim, SK Ghoshal, MA Saleh, T Kadni, MI Saripan, K Alzimami, Z Ibrahim, DA Bradley (2013)The Effect of TiO2 and MgO on the Thermo luminescence Properties of a Lithium Potassium Borate Glass System, In: JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS74(12)pp. 1816-1822 PERGAMON-ELSEVIER SCIENCE LTD
    Katie Ley, S.M. Jafari, Annika Lohstroh, Caroline Shenton-Taylor, David Bradley (2019)Thermoluminescent Response of Beta-irradiated Silica Beads, In: Radiation Physics and Chemistry154pp. 32-37 Elsevier

    Research into the potential for silica based materials as TLDs continues to increase, harnessing the various advantages that the materials have to offer as a dosimeter, including; affordability, chemical inertness, geometry and size, while producing suitable TL yields. Studies into the possibility of beta source dosimetry open another range of applications for this type of dosimeter, including procedures involving the possibility of in vivo dosimetry (Morino et al., 2002). This work aims to further investigate the properties of a much-studied batch of Mill Hill silica beads of various colours, irradiated with a SR90/Y90 source yielding a dose rate of 0.02 Gy/s, activity 37 MBq and maximum energy of 2.27 MeV, facilitated by the Ris ø TL/OSL reader. The TL yield is compared to that in previous work, with the same set of beads irradiated by a 6 MV photon beam provided by a Varian electron linac (Varian Medical Systems, Palo Alto, CA) X-ray source, delivering a dose of 10 Gy. Present study shows a decrease in the mass normalised TL yield from X-ray to beta source by a factor of 10, assumed to be accounted for by the estimated mean penetration depth of the beta particles in the doped silica beads. Investigating the potential for doped silica beads to be used as a beta source dosimeter a linearity study is reported with a dose range of 5 to 20 Gy. The studies show that all coloured beads except green show a strong conformity to a linear fit of the data over the tested range of doses. Fading studies conducted with clear petite beads (producing the greatest TL yield/mg) for doses of 5 Gy and 20 Gy have shown that the majority of fading occurs within the first hour following irradiation, with a plateau in the fading to approximately 17 % and 22 % loss of signal for 5 Gy and 20 Gy respectively in the interval of 24 hours to 70 hours after irradiation. The decay of the TL yield/mg was fitted to a logarithmic trend of reduction for both the 5 Gy and 20 Gy irradiation, with values of 0.9883 and 0.9705 respectively.

    S Hashim, YSM Alajerami, AT Ramli, SK Ghoshal, MA Saleh, ABA Kadir, MI Saripan, K Alzimami, DA Bradley, MHA Mhareb (2014)Thermoluminescence dosimetry properties and kinetic parameters of lithium potassium borate glass co-doped with titanium and magnesium oxides, In: APPLIED RADIATION AND ISOTOPES91pp. 126-130 PERGAMON-ELSEVIER SCIENCE LTD
    DA Bradley, W Kaabar, O Gundogdu, MJ Farquharson, M Janousch, M Bailey, C Jeynes (2010)Synchrotron and ion beam studies of the bone-cartilage interface, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT619(1-3)pp. 330-337 ELSEVIER SCIENCE BV
    ASS Shafiqah, YM Amin, RM Nor, N Tamchek, DA Bradley (2015)Enhanced TL response due to radiation induced defects in Ge-doped silica preforms, In: RADIATION PHYSICS AND CHEMISTRY111pp. 87-90 PERGAMON-ELSEVIER SCIENCE LTD
    ATA Rahman, NK Abu Bakar, MC Paul, DA Bradley (2014)Ultraviolet radiation (UVR) dosimetry system and the use of Ge-doped silica optical fibres, In: RADIATION PHYSICS AND CHEMISTRY104pp. 129-133 PERGAMON-ELSEVIER SCIENCE LTD
    David Bradley, SF Abdul Sani, AI Alalawi, Shakardokht Jafari, Andrew Nisbet, NM Noor, AR Hairul Azhar, GA Mahdiraji, N Tamchek, S Ghosh, MC Paul, KS Alzimami, MJ Maah (2014)Development of tailor-made silica fibres for TL dosimetry, In: Radiation Physics and Chemistry104pp. 3-9

    The Ge dopant in commercially available silica optical fibres gives rise to appreciable thermoluminscence (TL), weight-for-weight offering sensitivity to MV X-rays several times that of the LiF dosimeter TLD100. The response of these fibres to UV radiation, X-rays, electrons, protons, neutrons and alpha particles, with doses from a fraction of 1Gy up to 10kGy, have stimulated further investigation of the magnitude of the TL signal for intrinsic and doped SiO fibres. We represent a consortium effort between Malaysian partners and the University of Surrey, aimed at production of silica fibres with specific TL dosimetry applications, utilizing modified chemical vapour deposition (MCVD) doped silica-glass production and fibre-pulling facilities. The work is informed by defect and dopant concentration and various production dependences including pulling parameters such as temperature, speed and tension; the fibres also provide for spatial resolutions down to

    E Daar, KS Al Mugren, S Chika, S Barnes, DA Bradley (2015)XRF measurements of Zn, Sr and Pb in archaeological bone, In: X-RAY SPECTROMETRY44(3)pp. 129-134 WILEY-BLACKWELL
    S.F. Abdul Sani, R Hammond, Shakardokht Jafari, N Wahab, G Amouzad Mahdiraji, A S Siti Shafiqah, H A Abdul Rashid, M J Maah, H Aldousari, Mohammed Alkhorayef, M Alzimami, David Bradley (2016)Measurement of a wide-range of X-ray doses using specialty doped silica fibres, In: Radiation Physics and Chemistry137pp. 49-55

    Using six types of tailor-made doped optical fibres, we carry out thermoluminescent (TL) studies of X-rays, investigating the TL yield for doses from 20 mGy through to 50 Gy. Dosimetric parameters were investigated for nominal 8 wt% Ge doped fibres that in two cases were co-doped, using B in one case and Br in the other. A comparative measurement of surface analysis has also been made for non-annealed and annealed capillary fibres, use being made of X-ray Photoelectron Spectroscopy (XPS) analysis. Comparison was made with the conventional TL phosphor LiF in the form of the proprietary product TLD-100, including dose response and glow curves investigated for X-rays generated at 60 kVp over a dose range from 2 cGy to 50 Gy. The energy response of the fibres was also performed for X-rays generated at peak accelerating potentials of 80 kVp, 140 kVp, 250 kVp and 6 MV photons for an absorbed dose of 2 Gy. Present results show the samples to be suitable for use as TL dosimeters, with good linearity of response and a simple glow curve (simple trap) distribution. It has been established that the TL performance of an irradiated fibre is not only influenced by radiation parameters such as energy, dose-rate and total dose but also the type of fibre.

    NH Yaakob, H Wagiran, I Hossain, AT Ramli, DA Bradley, S Hashim, H Ali (2011)Electron irradiation response on Ge and Al-doped SiO2 optical fibres, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
    A Campbell, R Rawcliffe, A Guite, JCD Faria, A Mukherjee, MA McLachlan, M Shkunov, DDC Bradley (2016)Charge-Carrier Density Independent Mobility in Amorphous Fluorene-Triarylamine Copolymers, In: ADVANCED FUNCTIONAL MATERIALS26(21)pp. 3720-3729 WILEY-V C H VERLAG GMBH
    NE Norbani, NAA Salim, A Saat, Z Hamzah, AT Ramli, WMRW Idris, MZ Jaafar, DA Bradley, ATA Rahman (2014)Terrestrial gamma radiation dose rates (TGRD) from surface soil in Negeri Sembilan, Malaysia, In: RADIATION PHYSICS AND CHEMISTRY104pp. 112-117 PERGAMON-ELSEVIER SCIENCE LTD
    S Hashim, MI Saripan, ATA Rahman, NH Yaakob, DA Bradley, K Alzimami (2013)Effective Atomic Number of Ge-Doped and Al-Doped Optical Fibers for Radiation Dosimetry Purposes, In: IEEE TRANSACTIONS ON NUCLEAR SCIENCE60(2)pp. 555-559 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
    T Santawamaitre, D Malain, HA Al-Sulaiti, DA Bradley, MC Matthews, PH Regan (2014)Determination of U-238, Th-232 and K-40 activity concentrations in riverbank soil along the Chao Phraya river basin in Thailand, In: JOURNAL OF ENVIRONMENTAL RADIOACTIVITY138pp. 80-86 ELSEVIER SCI LTD
    E Dalah, D Bradley, A Nisbet (2010)Simulation of tissue activity curves of Cu-64-ATSM for sub-target volume delineation in radiotherapy, In: PHYSICS IN MEDICINE AND BIOLOGY55(3)pp. 681-694 IOP PUBLISHING LTD
    K Asaduzzaman, MU Khandaker, YM Amin, DA Bradley, RH Mahat, RM Nor (2014)Soil-to-root vegetable transfer factors for Ra-226, Th-232, K-40, and Y-88 in Malaysia, In: JOURNAL OF ENVIRONMENTAL RADIOACTIVITY135pp. 120-127 ELSEVIER SCI LTD
    Ming Tsuey Chew, Andrew Nisbet, Masao Suzuki, Naruhiro Matsufuji, Takeshi Murakami, Bleddyn Jones, David A. Bradley (2018)Potential lethal damage repair in glioblastoma cells irradiated with ion beams of various types and levels of linear energy transfer, In: Journal of Radiation Researchrry081 Oxford University Press

    Glioblastoma (GBM), a Grade IV brain tumour, is a well-known radioresistant cancer. To investigate one of the causes of radioresistance, we studied the capacity for potential lethal damage repair (PLDR) of three altered strains of GBM: T98G, U87 and LN18, irradiated with various ions and various levels of linear energy transfer (LET). The GBM cells were exposed to 12C and 28Si ion beams with LETs of 55, 100 and 200 keV/μm, and with X-ray beams of 1.7 keV/μm. Mono-energetic 12C ions and 28Si ions were generated by the Heavy Ion Medical Accelerator at the National Institute of Radiological Science, Chiba, Japan. Clonogenic assays were used to determine cell inactivation. The ability of the cells to repair potential lethal damage was demonstrated by allowing one identical set of irradiated cells to repair for 24 h before subplating. The results show there is definite PLDR with X-rays, some evidence of PLDR at 55 keV/μm, and minimal PLDR at 100 keV/μm. There is no observable PLDR at 200 keV/μm. This is the first study, to the authors’ knowledge, demonstrating the capability of GBM cells to repair potential lethal damage following charged ion irradiations. It is concluded that a GBM’s PLDR is dependent on LET, dose and GBM strain; and the more radioresistant the cell strain, the greater the PLDR.

    NM Noor, M Hussein, DA Bradley, A Nisbet (2010)The potential of Ge-doped optical fibre TL dosimetry for 3D verification of high energy IMRT photon beams, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment619(1-3)pp. 157-162 Elsevier
    OB Uwatse, MA Olatunji, MU Khandaker, YM Amin, DA Bradley, M Alkhorayef, K Alzimami (2015)Measurement of Natural and Artificial Radioactivity in Infant Powdered Milk and Estimation of the Corresponding Annual Effective Dose, In: ENVIRONMENTAL ENGINEERING SCIENCE32(10)pp. 838-846 MARY ANN LIEBERT, INC
    KS Alzimami, AM Maghraby, DA Bradley (2014)Comparative study of some new EPR dosimeters, In: RADIATION PHYSICS AND CHEMISTRY95pp. 109-112 PERGAMON-ELSEVIER SCIENCE LTD
    S Hashim, SA Ibrahim, SSC Omar, YSM Alajerami, MI Saripan, NM Noor, NM Ung, GA Mahdiraji, DA Bradley, K Alzimami (2014)Photon irradiation response of photonic crystal fibres and flat fibres at radiation therapy doses, In: APPLIED RADIATION AND ISOTOPES90pp. 258-260 PERGAMON-ELSEVIER SCIENCE LTD
    GA Mahdiraji, FRM Adikan, DA Bradley (2015)Collapsed optical fiber: A novel method for improving thermoluminescence response of optical fiber, In: JOURNAL OF LUMINESCENCE161pp. 442-447 ELSEVIER SCIENCE BV
    MA Alkhorayef, MA Alnaaimi, MA Alduaij, MO Mohamed, SY Ibahim, FA Alkandari, DA Bradley (2015)Toward standardising gamma camera quality control procedures, In: RADIATION PHYSICS AND CHEMISTRY116pp. 95-99 PERGAMON-ELSEVIER SCIENCE LTD
    H Shams, AD Bajoga, N Alazemi, DA Bradley, PH Regan (2016)A preliminary evaluation of naturally occurring radioactivity concentration levels across the State of Kuwait, In: APPLIED RADIATION AND ISOTOPES109pp. 479-481 PERGAMON-ELSEVIER SCIENCE LTD
    GA Mandiraji, M Ghomeishi, E Dermosesian, S Hashim, NM Ung, FRM Adikan, DA Bradley (2015)Optical fiber based dosimeter sensor: Beyond TLD-100 limits, In: SENSORS AND ACTUATORS A-PHYSICAL222pp. 48-57 ELSEVIER SCIENCE SA
    AT Abdul Rahman, E Bräuer-Krisch, T Brochard, J Adamovics, SK Clowes, D Bradley, SJ Doran (2011)Sophisticated test objects for the quality assurance of optical computed tomography scanners., In: Phys Med Biol56(14)pp. 4177-4199

    Optical computed tomography (CT), in conjunction with radiochromic gels and plastics, shows great potential for radiation therapy dose verification in 3D. However, an effective quality assurance (QA) regime for the various scanners currently available still remains to be developed. We show how the favourable properties of the PRESAGE® radiochromic polymer may be exploited to create highly sophisticated QA phantoms. Five 60 mm diameter cylindrical PRESAGE® samples were irradiated using the x-ray microbeam radiation therapy facility on the ID-17 biomedical beamline at the European Synchrotron Radiation Facility. Samples were then imaged on the University of Surrey parallel-beam optical CT scanner. The sample irradiations were designed to allow a variety of tests to be performed, including assessments of linearity, modulation transfer function (three independent measurements), geometric distortion and the effect of treatment fractionation. It is clear that, although the synchrotron method produces extremely high-quality test objects, it is not practical on a routine basis, because of its reliance on a highly specialized radiation source. Hence, we investigated a second possibility: three PRESAGE® samples were illuminated with ultraviolet light of wavelength 365 nm, using cheap masks created by laser-printing patterns onto overhead projector acetate sheets. There was good correlation between optical densities measured by the CT scanner and the expected UV 'dose' delivered. The results are encouraging and a proposal is made for a scanner test regime based on calibrated and well-characterized PRESAGE® samples.

    S Yalcin, O Gurler, O Gundogdu, DA Bradley (2012)A practical method for in-situ thickness determination using energy distribution of beta particles, In: APPLIED RADIATION AND ISOTOPES70(1)pp. 128-132 Elsevier
    K Wells, DA Bradley (2012)A review of X-ray explosives detection techniques for checked baggage, In: Applied Radiation and Isotopes70(8)pp. 1729-1746

    In recent times, the security focus for civil aviation has shifted from hijacking in the 1980s, towards deliberate sabotage. X-ray imaging provides a major tool in checked baggage inspection, with various sensitive techniques being brought to bear in determining the form, and density of items within luggage as well as other material dependent parameters. This review first examines the various challenges to X-ray technology in securing a safe system of passenger transportation. An overview is then presented of the various conventional and less conventional approaches that are available to the airline industry, leading to developments in state-of-the-art imaging technology supported by enhanced machine and observer-based decision making principles. © 2012 Elsevier Ltd.

    S. Hashim, R.S. Omar, S.K. Ghoshal, N.Z.H.A. Hanifah, D.A. Bradley, Y.J. Lee, C.L. Goh (2023)Dose assessment of Betatron electron beam: A key component of safe and secure industrial operations, In: Radiation physics and chemistry (Oxford, England : 1993)211 Elsevier Ltd

    For diverse industrial operations, the safety level of the electron beam generated by the Betatron has paramount significance, wherein the hazardous radiation dose requires constant monitoring and accurate evaluation. Human safety is the primary concern in using X-rays with high energy levels ranging from 3 to 20 MV for rapidly screening cargo containers and vehicles for security reasons. Considering these factors, we evaluated the radiation dosage associated with a typical 7.5 MV X-ray Betatron that is commonly used for full scanning of cargo and drivers in cargo security. The dose levels for organ equivalent, scanner boundary, and cargo were measured using TLD-100™ rod-type dosimeters, and RadEye™ B20-ER alpha-beta-gamma survey meter. The results indicated that the dose level measured at the scanner boundary while the X-ray was operating for 12 s fell within the standard range of 0.015–0.295 μSv/h that can be realistically achieved in public areas. Additionally, it was observed that this level was below the control limit of 0.5 μSv/h. Moreover, the evaluation of organ dose levels in the Anthropomorphic Alderson Radiation Therapy phantom revealed that the equivalent dose assessments for organs such as the gonads, brain (left and right), and lens (left and right) ranged from 0.01 to 0.08 mSv. This range of values is deemed acceptable for public exposure since it is below the annual dose limit of 1 mSv. It has been determined that the Betatron electron beam, utilized for full cargo security scans, is highly secure even for drivers. This disclosure could serve as a foundation for systematically evaluating dosage and disseminating information to increase public awareness and ensure environmental safety. •Evaluation of radiation exposure for both drivers and cargo during security scanning using a 7.5 MV Betatron.•The dose measured at the scanner boundary during a 12s operation was 0.015 to 0.295 µSv/h.•The dose assessments using ART phantom for gonads, brain and lens were between 0.01 to 0.08 mSv.

    D.A. Bradley, R.Z. Essa, Suat-Cheng Peh, Sin-Yeang Teow, Ming-Tsuey Chew, H.T. Zubair, Adebiyi Oresegun, Azmi Basaif, Kan Yeep Choo, Siti A. Ibrahim, Hairul Azhar Abdul-Rashid (2023)Low dose and low dose rate radioluminescence dosimetry, In: Applied radiation and isotopes198pp. 110875-110875 Elsevier Ltd

    Review is provided of a number of low-dose, low dose rate situations that in study require advances in the development of dosimetric facilities. Using a clinical linac set up to provide doses down to the few mGy level, the performance of a real-time radioluminescence system has then been illustrated, accommodating pulsed as well as continuous dose delivery. The system gate times provide for tracking of the pattern of dose delivery, allowing detailed account of dose and dose-rate variations. The system has been tested in both x-ray and electron mode dose delivery. •The need for Low-Dose Low Dose-Rate Dosimetry addressed.•Radioluminscence used in combination with linac set-up.•Live time pulse-by-pulse dosimetry demonstrated in low-dose regime.•Linearity with dose demonstrated.

    K.S.A.K. Bakar, N.M. Noor, M.F. Hassan, F. Idris, D.A. Bradley (2023)Dose mapping in Cesium-137 blood irradiator using novel Ge-doped silica optical fibres in comparison with gafchromic EBT-XD film: A preliminary study, In: Radiation physics and chemistry (Oxford, England : 1993)209 Elsevier Ltd

    The purpose of dose-mapping in blood irradiation is to ensure radiation dose delivered to the blood bags is within the specified limits of minimum 15 Gy and maximum 50 Gy, thus preventing any blood transfusion-related diseases. In the present study, we investigated the feasibility of novel fabricated germanium-doped (Ge-doped) silica-based optical fibre as a potential passive dosimeter for dose-mapping of a Cesium-137 (Cs-137) gamma blood irradiator. The calibration curve of optical fibres and Gafchromic EBT-XD film was established by irradiating the samples in the dose range from 5 to 35 Gy at the central of a water-equivalent phantom in a dedicated blood irradiator machine. For dose mapping, the fabricated optical fibres and EBT-XD film were irradiated for a gamma exposure of 8 min and 56 s to deliver a central dose of 25 Gy. Thermoluminescence measurements were performed using a Harshaw 3500 TLD reader at a maximum acquisition temperature of 400 °C. The results of optical fibres were compared with EBT-XD film. The absorbed dose obtained from optical fibres shows deviation of within 0.1%–10.4% compared to that of dose of the film. The fabricated optical fibre studied in this work have a good potential as a new passive dosimeter for characterisation and dose mapping of gamma blood irradiator due to its high sensitivity and reproducible characteristics. •We investigate the fabricated Ge-doped for dose-mapping of a blood irradiator.•The calibration curve of optical fibres and Gafchromic EBT-XD film was established.•The absorbed dose obtained from optical fibres shows deviation within 10.4% compared to that of dose of the film.•The fabricated optical fibre shows good potential to map dose.

    Siti Shafiqah A.S, S.F. Abdul Sani, Nizam Tamchek, K.S. Almugren, F.H. Alkallas, D.A. Bradley (2023)Defect characteristic of oxygen-deficient Ge-doped preform using photoluminescence spectroscopy, In: Radiation physics and chemistry (Oxford, England : 1993)210 Elsevier Ltd

    Study has been made of the Photoluminescence properties of Ge-doped silica preforms fabricated using the MCVD process and subsequently subjected to γ-ray irradiation. The photoluminescence emissions pointed to the presence of defects related to oxygen vacancies. Two types of preform were fabricated, obtained using a different flow rate and deposition temperature for each case. Results from the absorption spectra of the samples named as P1 and P2, show a signature absorption peak at 5.1 eV and 6.8 eV, indicative of oxygen-deficient and oxygen-rich defects respectively. Photoluminescence investigation have been carried out before and after the irradiation process with both samples reveal two main peaks at 1.5 eV. The highest intensity at 1.5 eV is known as an interaction between the Non- Bridging Oxygen Hole Centre (NBHOC) with the presence of impurity in the glass matrix. Upon irradiation, weak peak can be observed at 1.8 eV, sample P1 and P2, the PL intensity increases by a factor of 20 × and 50 × , respectively. This peak is associated with the oxygen deficient state in the sample. The peak referring to defect known as Germanium Lone Pair Centre (GLPC) are observed in both samples, peak shown at 3.1 eV, regardless of the Germanium Oxygen Deficient Centre (GODC) content. In regard to this, it can be concluded that this defect is generated independently in all germanium samples and are not correlated with the GODC band observed in the absorption band. •Photoluminescence properties of Ge-doped silica preforms (oxygen-deficient and oxygen-rich) irradiated to γ-ray.•GLPC are observed in both samples, regardless of the GODC content.•Defect generated are not correlated with the GODC band observed in the absorption band.

    Mayeen Uddin Khandaker, Mohamed M. Abuzaid, Ikhlas A. Mohamed, Mohamed Yousef, Saddig Jastaniah, Qurain T. Alshammari, Salem Saeed Alghamdi, Hamid Osman, Amna Mohamed Ahmed, Alamin Musa, Afaf Mohamed Ahmed Medani, S.E. Lam, D.A. Bradley (2023)Investigation of the Radiographer's adherence and compliance with radiation protection and infection control practices during COVID-19 mobile radiography, In: Radiation physics and chemistry (Oxford, England : 1993)210pp. 111023-111023 Elsevier Ltd

    Radiological staff, especially radiographers, work as front liners against the COVID-19 outbreak. This study aims to assess compliance with radiation protection and infection control practices during COVID-19 mobile radiography procedures. This cross-sectional study included 234 radiographers (females, 56%, n = 131; males, 44%, n = 103) who were asked to complete an online questionnaire consisting of demographic data, radiation protection and infection control practices during COVID-19 portable cases, and knowledge and awareness. After informed consent was completed, SPSS statistical software was used for the data analysis. The most common age group of participants ranged from 18 to 25 years old (30.3%, n = 71). Bachelor's degree holders were 74.4% (n = 174). Most radiographers (39.7%, n = 93) had a working experience of 1–5 years, followed by 27.8% (n = 65) with more than 16 years of experience. Most respondents (62.4%, n = 146) handled approximately 1–5 cases daily, the majority of them (56%, n = 131) stated affirmatively they had obtained special training to handle COVID-19, and when inquired if they had received any special allowances for handling COVID-19 suspected/confirmed cases most of them stated negative (73.9%, n = 173). Most participants stated that they always wear a TLD during portable cases (67.1%, n = 157) and a lead apron (51.7%, n = 121). Around 73% (n = 171) knew the latest information on COVID-19 and attended the COVID-19 awareness course. A significant association was found between the work experience of the radiographers and their responses to following the best practices (p = 0.018, α = 0.05). Radiographers who had COVID-19 training (μ = 48.78) tend to adhere more to best practices than those who have not (p = 0.04, α = 0.05). Further, respondents who handled more than 16/more COVID-19 suspected/confirmed cases followed the best practices more (μ = 50.38) than those who handled less (p = 0.04, α = 0.05). This study revealed detailed information on radiation protection and infection control practices during COVID-19 mobile radiography. It has been observed that the participants/radiographers have good knowledge and awareness of radiation protection and infection-control practices. The present results may be used to plan future requirements regarding resources and training to ensure patient safety. •Radiographer's compliance with radiation protection for COVID-19 cases is studied.•COVID-19 infection to radiology personnel is due to poor understanding of the virus.•Isolation bag device reduces the risk of contamination in the radiology department.•Present results help to plan future requirements on resources toward patient safety.

    Tayaallen Ramachandran, Mohammad Rashed Iqbal Faruque, Mohammad Tariqul Islam, Mayeen Uddin Khandaker, Amal Alqahtani, D A Bradley (2022)Development and Analysis of Coding and Tailored Metamaterial for Terahertz Frequency Applications, In: Materials15(8)

    This study represents the development and analysis of the types of metamaterial structures for terahertz frequency. Recently, investigations about unique coding metamaterial have become well-known among the scientific community since it can manipulate electromagnetic (EM) waves by utilizing various coding sequences. Therefore, several coding and tailored metamaterial designs were compared and numerically analyzed the performances in this research work. The 1-bit coding metamaterial made up of only "0" and "1" elements by adopting two types of unit cells with 0 and π phase responses were analyzed for the coding metamaterial. Moreover, for the numerical simulation analyses, the well-known Computer Simulation Technology (CST) Microwave Studio software was adopted. This investigation focused on the frequency ranges from 0 to 5 THz. On the other hand, the proposed designs were simulated to find their scattering parameter behavior. The comparison of coding and tailored metamaterial revealed slight differences in the RCS values. The coding metamaterial designs manifested RCS values less than -50 dBm , while tailored metamaterial designs exhibited less than -60 dBm . Furthermore, the proposed designs displayed various transmission coefficient result curves for both types of metamaterial. Moreover, the bistatic far-field scattering patterns of both metamaterial designs were presented in this work. In a nutshell, the 1-bit coding metamaterial with a unique sequence can influence the EM waves and realize different functionalities.

    D.A. Bradley, Siti Nurasiah Mat Nawi, Mayeen Uddin Khandaker, K.S. Almugren, S.F Abdul Sani (2020)Sub kGy photon irradiation alterations in graphite, In: Applied radiation and isotopes161pp. 109168-109168 Elsevier Ltd

    Present work concerns polymer pencil-lead graphite (PPLG) and the potential use of these in elucidating irradiation-driven structural alterations. The study provides detailed analysis of radiation-induced structural interaction changes and the associated luminescence that originates from the energy absorption. Thermally stimulated emission from the different occupied defect energy levels reflects the received radiation dose, different for the different diameter PPLGs. The PPLG samples have been exposed to photon irradiation, specifically x-ray doses ranging from 1 to 10 Gy, extended to 30–200 Gy through use of a60Co gamma-ray source. Trapping parameters such as order of kinetics, activation energy and frequency factor are estimated using Chen's peak-shape method for a fixed-dose of 30 Gy. X-ray diffractometry was used to characterize the crystal structure of the PPLG, the aim being to identify the degree of structural order, atomic spacing and lattice constants of the various irradiated PPLG samples. The mean atomic spacing and degree of structural order for the different diameter PPLG are found to be 0.3332 nm and 26.6° respectively. Photoluminescence spectra from PPLG arising from diode laser excitation at 532 nm consist of two adjacent peaks, 602 nm (absorption) and 1074 nm (emission), with mean energy band gap values within the range 1.113–1.133 eV. •Sub kGy (1–200 Gy) photon irradiations made of various diameter polymer coated pencil-lead.•Structural alterations investigated via TL analysis, photoluminescence and x-ray diffraction.•The underpinning defects are analyzed via the glow-curve peak-shape method.•The irradiation effects are readily linked to changes occurring at the microscopic level.

    Amal Alqahtani, S.F. Abdul Sani, N.H. Amiera Narissa, Abdulaziz Alanazi, Z. Podolyak, A. Nisbet, D.A. Bradley (2020)Microscope cover-slip glass for TLD applications, In: Applied radiation and isotopes160pp. 109132-109132 Elsevier Ltd

    As a result of the various evolving needs, thermoluminescence dosimetry is constantly under development, with applications intended in environmental and personal radiation monitoring through to the sensing of radiotherapy and radiation processing doses. In radiotherapy dosimetry challenges include small-field profile evaluation, encompassing the fine beams of radiosurgery, evaluations confronting the steep dose gradients of electronic brachytherapy and the high dose rates of FLASH radiotherapy. Current work concerns the thermoluminescent dosimetric properties of commercial low-cost borosilicate glass in the form of thin (sub-mm to a few mm) plates, use being made of microscope cover-slips irradiated using clinical external-beam radiotherapy facilities as well as through use of 60Co gamma irradiators. In using megavoltage photons and MeV electrons, characterization of the dosimetric response has been made for cover-slips of thicknesses up to 4 mm. Reproducibility to within +/5% has been obtained. In particular, for doses up to 10 Gy, the borosilicate cover-slips have been demonstrated to have considerable potential for use in high spatial resolution radiotherapy dosimetry, down to 0.13 mm in present work, with a coefficient of determination in respect of linearity of >0.99 for the thinner cover-slips. Results are also presented for 0.13- and 1.00-mm thick cover slips irradiated to 60Co gamma-ray doses, initially in the range 5- to 25 Gy, subsequently extended to 5 kGy–25 kGy, again providing linear response.

    Mayeen Khandaker, Nur Zainuddin, D A Bradley, MRI Faruque, F I Almasoud, M I Sayyed, A Sulieman, P J Jojo (2020)Radiation dose to Malaysian populace via the consumption of roasted ground and instant coffee, In: Radiation physics and chemistry (Oxford, England : 1993)173 Elsevier BV

    Accompanying the busy lifestyles of modern Malaysia, coffee is becoming one of the nations' most popular stimulating drinks. In association with nutrients uptake, natural radionuclides in soil are also being taken up by the coffee plant, subsequently appearing in the human body through consumption of coffee. Present study concerns the assessment of the natural radionuclides 226Ra, 228Ra, and 40K in roasted ground and instant coffee consumed in Malaysia. A total of 12 sampled brands of coffee, originating from seven different countries including Malaysia, were collected from various supermarkets in Kuala Lumpur. The samples were analyzed by HPGe γ-ray spectrometry, obtaining a range of activities (in Bq/kg) 6.4 ± 1.3–21.4 ± 2.4, 6.6 ± 1.8–47.9 ± 10.6, and 220 ± 12–1510 ± 72 for 226Ra, 228Ra and 40K respectively. The annual committed effective dose estimate from such coffee consumption was found to be in the range 13.2–55.7 μSv/y, low in comparison with the UNSCEAR (2000) reference dose guidance limit of 290 μSv/y. The estimated threshold coffee consumption rates indicates a guidance limitation for Sample L of not more than 21 g/d (some 2 cups/d) to avoid deleterious health effect. While the presently sampled coffee brands do not represent a public concern in terms of radiological risk, cumulative daily dietary exposures from other or present brands may not be totally negligible because of the UNSCEAR reference limit is due to the contribution from all natural sources. Thus, periodic monitoring of radiation levels in coffee is suggested to be of importance.

    Anton Johannes Veldhuis, Jane Glover, David Bradley, Kourosh Behzadian, Alma López-Avilés, Julian Cottee, Clare Downing, John Ingram, Matthew Leach, Raziyeh Farmani, David Butler, Andy Pike, Lisa De Propris, Laura Purvis, Pamela Robinson, Aidong Yang (2019)Re-distributed manufacturing and the food-water-energy nexus: opportunities and challenges, In: Production planning & control30(7)pp. 593-609 Taylor & Francis

    Addressing the intersection of two important emerging research areas, re-distributed manufacturing (RDM) and the food-energy-water (FEW) nexus, this work combines insights from engineering, business and policy perspectives and explores opportunities and challenges towards a more localized and sustainable food system. Analysis centred on two specific food products, namely bread and tomato paste reveals that the feasibility and potential of RDM vary with the type of food product and the supply chain (SC) components. Physically, energy efficiency, water consumption and reduction of waste and carbon footprint may be affected by scale and location of production activities and potentials of industrial symbiosis. From the business perspective, novel products, new markets and new business models are expected in order for food RDM to penetrate within the established food industry. Studies on policies, through the lens of public procurement, call for solid evidence of envisioned environmental, social and economic benefits of a more localized food system. An initial integrated framework is proposed for understanding and assessing food RDM and the FEW nexus.

    M. Alkhorayef, H. I. Al-Mohammed, Fareed H. Mayhoub, Abdelmoneim Sulieman, Hassan Salah, M. Yousef, Othman I. Alomair, D. A. Bradley (2021)Staff radiation dose and estimated risk in an interventional radiology department, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier

    In interventional radiology attendant staff can be exposed to significant doses from the radiation scattered from the patient, giving rise to heterogeneous energy distribution, exposure occurring over extended periods of time. Protection of staff is a prime concern, also including reducing the risk of carcinogenesis. With only limited published studies available, as in for instance in regard to lens opacifications, further evaluation of staff exposures and assessment of radiation protection techniques and measures are crucial. Present study has sought to evaluate staff radiation exposure in a radiology department that performs interventional procedures. Annual occupational exposures were obtained for 32 personnel (6 females and 26 males) in a radiology department at a tertiary hospital. Personal dose equivalent H-p (d) was measured in terms of H-p (0.07) (shallow dose) and H-p (10) (deep dose). The measurements were made over a period of two consecutive years, 2017 and 2018, use being made of TLD-100 thermoluminescent dosimeters. In units of mSv, the corresponding average annual dose equivalent and range for H-p (10) and H-p (0.07) were 4.6 +/- 7.0 (0.1-25.5) and 5.1 +/- 7.3 (0.1-25.5). Notably, 16% of staff received doses that were greater than the annual dose limit. Since H-p (10) offers a conservative evaluation of effective dose, evaluation of the working environment is necessary in seeking to ensure dose values remain below annual dose limits.

    F. Moradi, Kh Rezaee Ebrahim Saraee, S. F. Abdul Sani, D. A. Bradley (2021)Metallic nanoparticle radiosensitization: The role of Monte Carlo simulations towards progress, In: Radiation physics and chemistry (Oxford, England : 1993)180 Elsevier

    Metallic nanoparticle radiosensitization (MNPR) is attracting a good deal of attention, promising enhanced efficiency target volume radiation therapy without escalation of damage to surrounding normal tissues, also devoid of modification to the irradiation setup. To study the process of DNA damage in MNPR, physical dose in the subcellular scale should be known. This, together with the lack of accurate measurement methods, has demanded micro and nanodosimetric calculations. Accordingly, Monte Carlo (MC) simulations have been supportive with evaluation of physical effects in the radioenhancement process, which together with experimental findings resulted in improved understanding of the underlying chemical and biological processes. This review discusses current progress in nanoparticle (NP) radiosensitization, summarizing findings from both experiment and MC simulation in respect of the various parameters that affect the efficiency of radioenhancement in photon and charged particle therapies. We describe the role of MC transport calculations in progress of NP radioenhancement and discuss the main perceptions achieved in use of MC simulations along with biological survival studies. Current challenges of MC simulations for the use in this field and future potentials are also discussed.

    M.Z.I. Mollah, M.R.I. Faruque, D.A. Bradley, M.U. Khandaker, Saphwan Al Assaf (2023)FTIR and rheology study of alginate samples: Effect of radiation, In: Radiation physics and chemistry (Oxford, England : 1993)202
    Nuha Al-Harbi, M I Sayyed, Yas Al-Hadeethi, Ashok Kumar, M Elsafi, K A Mahmoud, Mayeen Khandaker, D A Bradley (2021)A novel CaO–K2O–Na2O–P2O5 glass systems for radiation shielding applications, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier BV

    A novel phosphate-based glass system was fabricated to be applied in some dental applications. The fabricated glass system consists of non-toxic CaO–K2O–Na2O– P2O5 compounds and described by the chemical formula (40 + x) P2O5+20CaO+(30-x) Na2O+10K2O, where 0 = x ≤ 20 mol%. The absorption spectra of the fabricated glasses were recorded by the UV–Vis spectrophotometer in the wavelength range 200–1100 nm. The refractive index found to be decreased from 2.438 to 2.328, while the direct energy gap was enhanced from 3.626 to 3.880 eV with increasing the P2O5 concentration. Moreover, the fabricated glass system's gamma-ray shielding capacity was examined using the Geant 4 simulation code, and compared with the NIST photon cross-section database (XCOM) in the energy region between 0.161 and 2.51 MeV. The highest linear attenuation coefficient (LAC) was obtained for glass samples with 40 mol% of P2O5, varied between 0.326 and 0.091 cm−1. In contrast, the lowest LAC was achieved for glass samples with 60 mol% of the P2O5 compounds, decreased from 0.301 to 0.087 cm−1 when the gamma photon energy was raised from 0.161 to 2.51 MeV, respectively.

    Mengge Dong, Suying Zhou, Xiangxin Xue, Xiating Feng, M. Sayyed, Mayeen Uddin Khandaker, D. A. Bradley (2021)The potential use of boron containing resources for protection against nuclear radiation, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier

    Recognizing the large neutron capture cross section of boron, the suitability of boron containing resources are studied for protection against nuclear radiation. Experimental and simulation study for neutron (thermal and fast) and gamma-ray shielding features of six different types of boron containing natural materials, obtained from the utilization process of boron ores in Liaoning Province of China, are performed here. Shielding ability of B1-B6 for thermal neutron is mainly based on the on the absorption cross section of boron; The elements with higher content or cross section have higher contribution for the fast neutron shielding; The interactions of B1-B6 with gamma rays are different with each other because of the difference components, but the mainly are Photoelectric Absorption in the low energy region, Incoherent Scattering in the intermediate energy region and Pair Production in nuclear filed in the high energy region, the elements with higher content or high atomic number show higher contribution for the shielding performance. The neutron and gamma ray shielding show a positive correlation with the boron content and material density, respectively. Comprehensive shielding performance of the studied samples is found to be better than some commercial materials. Overall, the composites prepared by boron containing resources and epoxy resin show excellent shielding performances for neutron but poor for gamma rays. Particularly, the boron rich slag shows the greater performance for both neutron and gamma ray shielding. The obtained results show the pathway for potential use of boron containing resources as structural materials in the radiation environment, and provide protection to both radiation worker and general populace from harmful nuclear radiation.

    Mayeen Uddin Khandaker, S. N. Mat Nawi, S. F. Abdul Sani, Julia A. Karim, K. S. Almugren, D. A. Bradley (2022)Defects and structural changes of graphite-rich media subjected to low-level neutron doses for radiation dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)201 Elsevier

    Using commercially available, 0.3 mm thick rod-shaped, highly uniform 2B and HB grade polymer pencil lead graphite (PPLG), and subjected to a low-level neutron dose range of 2-10 Gy, a comprehensive understanding of radiation-induced effects have been achieved. The thermoluminescence (TL) and photoluminescence (PL) dose dependency, as well as changes in Raman spectroscopic characteristics, have been studied in order to understand the nature and distribution of defects in its crystal lattice structures that produce the luminescence signal. The atomic spacing, lattice constant, and the degree of structural order of the irradiated samples have been the primary focuses of the X-ray diffraction (XRD) study, which has then been followed by crystallite size calculations. The findings make it abundantly evident that neutron irradiation of different doses leads to some structural alteration in the studied sample at the microscopic level. Within the investigated dose range, all of the samples displayed an excellent linear response, with the sensitivity of the 2B grade PPLG being significantly higher than that of the HB. The findings show that the PPLG can be employed as a dosimetric medium for neutron radiation field. PPLG can provide a low-cost, highly effective system for researching radiation-driven changes in carbon, and all results anticipate 2B grade of PPLG to be a valuable material for new generation radiation dosimetry.

    Sabina Yasmin, Mayeen Uddin Khandaker, Siti Nurasiah Mat Nawi, Siti Fairus Abdul Sani, D.A. Bradley, Amal Alqahtani, Mohammad Rashed Iqbal Faruque (2022)The effectiveness of ornamental building materials (tiles) for retrospective thermoluminescence dosimetry, In: Applied radiation and isotopes184pp. 110218-110218 Elsevier Ltd

    Like many other decorative building materials, tiles are one of the most precious ornamental ingredients for making a lucrative building image. It not only offers beauty and luxury but also added value by protecting/monitoring ionizing radiation. In this study, the utmost regular use of seven varieties of tile samples has been considered for retrospective thermoluminescence dosimetry. To observe the potentials of tiles for retrospective dosimetry, the major thermoluminescence properties (such as dose-response, energy dependence, self-sensitivity, relative sensitivity, glow curves, repeatability, fading, and also effective atomic number) has been investigated following the annealing - irradiation – readout cycles. Making an allowance for the various TL parameters, White Horse (Mirror Polish) tiles demonstrate suitability to be used as emergency TL dosimeter in 0.5–100 Gy dose array. Comparing the values of Zeff of these numerous tiles’ samples (11.6–12.7) with TLD-200 (Zeff = 16.3), it is to be noted that tiles can be used as a suitable material for environmental radiation dosimetry. The thermoluminescent characteristics of tiles in the dose limit from 0.5 Gy to 100 Gy are reported here for the first time. •Commercially available widely used tiles in Bangladeshi dwellings are studied for retrospective dosimetry.•Tiles of the “White Horse (Mirror Polish)” brand show good TL features.•This is the first study for upgrading the measurement process in the dose range of 0.5–100 Gy.

    Siok Ee Lam, Siti Nurasiah Mat Nawi, Siti Fairus Abdul Sani, Mayeen Uddin Khandaker, David Andrew Bradley (2021)Raman and photoluminescence spectroscopy analysis of gamma irradiated human hair, In: Scientific reports11(1)pp. 7939-7939 NATURE PORTFOLIO

    Preliminary study has been made of black human hair, carbon concentration of some 53%, a model in examining the potential of hair of the human head in retrospective and emergency biodosimetry applications, also offering effective atomic number near to that of water. The hair samples were exposed to 60Co gamma rays, delivering doses from 0 to 200 Gy. Structural alterations were observed, use being made of Raman and photoluminescence (PL) spectroscopy. Most prominent among the features observed in the first-order Raman spectra are the D and G peaks, appearing at 1370 +/- 18 cm- 1 and 1589 +/- 11 cm- 1 respectively, the intensity ratio I D/ I G indicating dose-dependent defects generation and annealing of structural alterations. The wavelengths of the PL absorption and emission peaks are found to be centred at 592.3 +/- 12.5 nm and 1077.4 +/- 7.3 nm, respectively. The hair samples mean band gap energy ( E g) post-irradiation was found to be 2.10 +/- 0.04 eV, of the order of a semiconductor and approximately two times the E g of other carbon-rich materials reported via the same methodology.

    S Abdul Sani, M Othman, Amal Alqahtani, K Almugren, F Alkallas, D Bradley (2020)Low-cost commercial borosilicate glass slides for passive radiation dosimetry, In: PloS one15(12)pp. e0241550-e0241550 Public Library of Science

    For x- and gamma- irradiations delivering entrance doses from 2- up to 1000 Gy to commercial 1.0 mm thick borosilicate glass microscope slides, study has been made of their thermoluminescence yield. With an effective atomic number of 10.6 (approximating bone equivalence), photon energy dependency is apparent in the low x-ray energy range, with interplay between the photoelectric effect and attenuation. As an example, over the examined dose range, at 120 kVp the photon sensitivity has been found to be some 5× that of 60Co gamma irradiations, also with repeatability to within ~1%. The glow-curves, taking the form of a single prominent broad peak, have been deconvolved yielding at best fit a total of five peaks, the associated activation energies and frequency factors also being obtained. The results indicate borosilicate glass slides to offer promising performance as a low-cost passive radiation dosimeter, with utility for both radiotherapy and industrial applications.

    Md Salah Uddin Afsar, Mohammad Rashed Iqbal Faruque, Md Bellal Hossain, Air Mohammad Siddiky, Mayeen Uddin Khandaker, Amal Alqahtani, D. A. Bradley (2022)A New Octagonal Close Ring Resonator Based Dumbbell-Shaped Tuning Fork Perfect Metamaterial Absorber for C- and Ku-Band Applications, In: Micromachines (Basel)13(2) Mdpi

    In this paper, a new octagonal close ring resonator (OCRR)-based dumbbell-shaped tuning fork perfect metamaterial absorber for C- and Ku-band applications is presented. This design is a new combination of an octagonal ring close ring resonator with two dumbbell-shaped tuning forks metal strips integrated on epoxy resin dielectric substrate. The proposed perfect metamaterial absorber (PMA) is assessed by finite-integration technique (FIT)-based electromagnetic simulator-Computer simulation technology (CST) software. The anticipated assembly reveals dual resonance frequencies of 6.45 GHz and 14.89 GHz at 99.15% and 99.76% absorption, respectively, for TE incidence. The projected design is augmented through various types of parametric studies, such as design optimization, the effect of the octagonal ring resonator width, and varying the split gap of the double tuning fork. The numerical results are also investigated and verified using the equivalent circuit model, another electromagnetic simulator high frequency structural simulator (HFSS), and different array combinations that showed very negligible disparity. The TE polarization wave is applied to analyze the absorption separately and oblique incidence angle showing polarization insensitivity up to 30 degrees and wide incident angle up to 60 degrees. The presented metamaterial absorber is suitable for satellite communication bands, stealth-coating technology, and defense and security applications.

    A. Sulieman, A. Abdelrazig, M. Alkhorayef, E. Babikir, H.I. Al-Mohammed, K.S. Al-Mugren, D. Bradley (2019)Patient effective doses and radiation risks in cardiac catheterization procedures, In: Radiation physics and chemistry (Oxford, England : 1993)157pp. 54-59 Elsevier Ltd

    Cardiac catheterizations (CC) represent a set of interventional procedure used in the diagnosis and treatment of coronary arteries diseases. Whereas interventional procedures perhaps represent only some 12% of all radiological procedures they nevertheless contribute about 48% of the total collective dose worldwide. In a Sudanese based study, the objectives of present work have been to evaluate patient radiation dose and to estimate effective doses and cancer risks for three types of cardiac catheterization procedure. Radiation doses and the associated radiation risks have been evaluated for a total of 346 patients undergoing treatments for a range of clinical indications, including 187 Diagnostic Coronary Angiographic (DCA) procedures (54%), 118 Percutaneous Coronary Interventions (PCI) (34.1%) and 41 Pacemaker (PM) procedures (11.9%)). The respective effective dose ranges were 4.0- to 59.3 mSv, 11.4- to 175 mSv and 7.2- to 51.5 mSv. None of the present patient cohort developed tissue reactions, deterministic effects clearly being anathema in diagnostic radiological practice. With optimization of patient doses being fundamental to best practice, and with it an associated mitigation of stochastic risk, not least in regard to patients of younger age facing the greatest risk, there is particular concern regarding training and experience of radiographic staff, as results show. •Radiation dose survey for patients undergoing certain cardiac catheterization procedures.•Patient dose was measured using calibrated kerma area product (KAP) meter.•In complex procedures, patient may receive a higher doses that may lead to tissue reaction (erythema).•A radiation dose registry was initiated to monitor patient received a dose above 1.5 Gy for erythema detection.

    N.N.M. Rais, D.A. Bradley, A. Hashim, N.D. Osman, N.M. Noor (2019)Fabricated germanium-doped fibres for computed tomography dosimetry, In: Applied radiation and isotopes153pp. 108810-108810 Elsevier Ltd

    For a range of doses familiarly incurred in computed tomography (CT), study is made of the performance of Germanium (Ge)-doped fibre dosimeters formed into cylindrical and flat shapes. Indigenously fabricated 2.3 mol% and 6 mol% Ge-dopant concentration preforms have been used to produce flat- and cylindrical-fibres (FF and CF) of various size and diameters; an additional 4 mol% Ge-doped commercial fibre with a core diameter of 50 μm has also been used. The key characteristics examined include the linearity index f(d), dose sensitivity and minimum detectable dose (MDD), the performance of the fibres being compared against that of lithium-fluoride based TLD-100 thermoluminescence (TL) dosimeters. For doses in the range 2-40 milligray (mGy), delivered at constant potential of 120 kilovoltage (kV), both the fabricated and commercial fibres demonstrate supralinear behaviours at doses  4 mGy. In terms of dose sensitivity, all of the fibres show superior TL sensitivity when compared against TLD-100, the 2.3 mol% and 6 mol% Ge-doped FF demonstrating the greatest TL sensitivity at 84 and 87 times that of TLD-100. The TL yields for the novel Ge-doped silica glass render them appealing for use within the present medical imaging dose range, offering linearity at high sensitivity down to less than 2 mGy. •The fabricated 2.3 mol% and 6 mol% Germanium (Ge)-doped fibres are investigated for computed tomography dosimetry.•Linearity index, dose sensitivity and minimum detectable dose (MDD) for the fibres are compared against TLD-100.•The novel Ge-doped fibres offering linearity at high sensitivity down to less than 2 mGy.

    Ibrahim I. Suliman, Lamia H. Salih, Dua M. Ali, Abdulaziz S. Alaamer, M.A. Al-Rajhi, M. Alkhorayef, D.A. Bradley (2020)Reprint of “Occupational exposure in nuclear medicine and interventional cardiology departments in Sudan: Are they following radiation protection standards?”, In: Radiation physics and chemistry (Oxford, England : 1993)167 Elsevier Ltd

    Monitoring of staff's radiation exposure in medicine is an important radiation protection task. This study aimed to measure the staff doses in the nuclear medicine (NM) and interventional cardiology (IC) departments in Sudan and assess whether the measured doses fall within the recommended radiation protection standards. 37 members of staff involved in the NM and IC procedures were monitored using electronic personal dosimeters (EPDs). In IC, the average monthly Hp (10) values ranged from 30.0 to 38.9 µSv (to cardiologists), from 3.6 to 13.5 µSv (to nurses), and from 3.5 to 8.9 µSv (to technologists). The annual effective dose ranged from 1.95 to 2.53 mSv (to cardiologists), from 0.23 to 0.88 mSv (to nurses), and from 0.23 to 0.56 mSv (to technologists). In NM, the monthly Hp (10) values ranged between 83.0 and 84.0 µSv (to nurses), 38.8 and 54.0 µSv (to pharmacists), 16.9 and 70.2 µSv (to technologists), 40.2 and 76.6 µSv (to physicists). The annual effective doses ranged from 0.91 to 0.92 mSv (to nurses), 0.43–0.59 mSv (to pharmacists), 0.19–0.77 mSv (to technologists), and 0.44–0.84 mSv (to physicists). The estimated doses fall below the recommended annual dose limit. However, the lack of a radiation surveillance program and use of occupational exposure control tools are of concern in both the IC and NM departments. •Dose to staff were studied in nuclear medicine (NM) and interventional cardiology (IC) in Sudan.•In IC procedures, the estimated annual effective doses were: 1.95–2.53 mSv varied.•In NM procedures, the estimated annual effective doses were: 0.19–0.92 mSv varied.•Doses are below the annual dose limit but occupational exposure control tools are lacking.•The data are important in promoting radiation protection good practices at workplaces.

    Amjad Alyahyawi, T Jupp, M Alkhorayef, D A Bradley (2018)Tailor-made Ge-doped silica-glass for clinical diagnostic X-ray dosimetry, In: Applied radiation and isotopes138pp. 45-49

    In the modern clinical practice of diagnostic radiology there is a growing demand for radiation dosimetry, it also being recognized that with increasing use of X-ray examinations additional population dose will result, accompanied by an additional albeit low potential for genetic consequences. At the doses typical of diagnostic radiology there is also a low statistical risk for cancer induction; in adhering to best practice, to be also implied is a low but non-negligible potential for deterministic sensitive organ responses, including in regard to the skin and eyes. Risk reduction is important, in line with the principle of ALARP, both in regard to staff and patients alike; for the latter modern practice is usually guided by Dose Reference Levels (DRL) while for the former and members of the public, legislated controls (supported by safe working practices) pertain. As such, effective, reliable and accurate means of dosimetry are required in support of these actions. Recent studies have shown that Ge-doped-silica glass fibres offer several advantages over the well-established phosphor-based TL dosimeters (TLD), including excellent sensitivity at diagnostic doses as demonstrated herein, low fading, good reproducibility and re-usability, as well as representing a water impervious, robust dosimetric system. In addition, these silica-based fibres show good linearity over a wide dynamic range of dose and dose-rate and are directionally independent. In the present study, we investigate tailor made doped-silica glass thermoluminescence (TL) for applications in medical diagnostic imaging dosimetry. The aim is to develop a dosimeter of sensitivity greater than that of the commonly used LiF (Mg,Ti) phosphor. We examine the ability of such doped glass media to detect the typically low levels of radiation in diagnostic applications (from fractions of a mGy through to several mGy or more), including, mammography and dental radiology, use being made of x-ray tubes located at the Royal Surrey County Hospital. We further examine dose-linearity, energy response and fading.

    A. Sulieman, Fareed H. Mayhoub, Hassan Salah, H.I. Al-Mohammed, M. Alkhorayef, B. Moftah, M. Al Rowaily, D.A. Bradley (2020)Occupational and ambient radiation exposures from Lu-177 DOTATATE during targeted therapy, In: Applied radiation and isotopes164pp. 109240-109240
    A. N. Edam, A. Sulieman, N. Tamam, E. Abuelhaia, I. Salih, A. K. Sam, M. Yousef, M. Alkhorayef, D. A. Bradley (2021)Current Sudan protective practice in diagnostic nuclear medicine and patient dose, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier

    Reflecting upon the influence of current diagnostic imaging radiation protection practices in Sudan, a sampling evaluation is made of administered activity across all five of the nuclear medicine departments in the country. Data were collected in respect of 423 patients, administered nuclide activities showing accord with international levels. For administered activity, four of the five departments use International Atomic Energy Agency (IAEA) Basic Safety Standard protocols, the other adopting UK Administration of Radioactive Substances Advisory Committee (ARSAC) practice. For national nuclear medicine diagnostic purposes overwhelming use is made of Tc-99m. Thyroid and parathyroid scans account for 43% of the 423 investigations, while whole body bone and renal scans provide for the imaging needs of the respective 34% and 23% remaining patients. Of the acquired images, in excess of 80% of these were planar. The mean and standard deviation effective dose values were 2.26 +/- 0.61, 4.70 +/- 0.77 and 1.03 +/- 0.29 mSv, for thyroid, bone and dynamic renal scans respectively, comparable with that of previous studies. While department designs are observed to comply with radiation protection regulations, the personal monitoring service is much less satisfactory, data frequently being found to be absent in all five departments. Moreover, only 60% of the medical physicists have been in receipt of regular radiation protection training, while other medical staff within the departments have not benefited from the relevant training at all, including physicians, nurses and nuclear medicine technologists. None have received regular specific medical checks. Accordingly, the Sudanese Nuclear & Radiological Regulatory Authority are now playing a major role in development of nuclear medicine practice and associated safety requirements, seeking accord with the principle of ALARA. Physician/medical physicist cooperation is needed in addressing optimization of radiation dose and image quality, also radiation protection awareness and training, as well as in medical surveillance.

    Ibrahim I. Suliman, Lamia H. Salih, Dua M. Ali, Abdulaziz S. Alaamer, M.A. Al-Rajhi, M. Alkhorayef, D.A. Bradley (2019)Occupational exposure in nuclear medicine and interventional cardiology departments in Sudan: Are they following radiation protection standards?, In: Radiation physics and chemistry (Oxford, England : 1993)160pp. 100-104 Elsevier Ltd

    Monitoring of staff's radiation exposure in medicine is an important radiation protection task. This study aimed to measure the staff doses in the nuclear medicine (NM) and interventional cardiology (IC) departments in Sudan and assess whether the measured doses fall within the recommended radiation protection standards. 37 members of staff involved in the NM and IC procedures were monitored using electronic personal dosimeters (EPDs). In IC, the average monthly Hp (10) values ranged from 30.0 to 38.9 µSv (to cardiologists), from 3.6 to 13.5 µSv (to nurses), and from 3.5 to 8.9 µSv (to technologists). The annual effective dose ranged from 1.95 to 2.53 mSv (to cardiologists), from 0.23 to 0.88 mSv (to nurses), and from 0.23 to 0.56 mSv (to technologists). In NM, the monthly Hp (10) values ranged between 83.0 and 84.0 µSv (to nurses), 38.8 and 54.0 µSv (to pharmacists), 16.9 and 70.2 µSv (to technologists), 40.2 and 76.6 µSv (to physicists). The annual effective doses ranged from 0.91 to 0.92 mSv (to nurses), 0.43–0.59 mSv (to pharmacists), 0.19–0.77 mSv (to technologists), and 0.44–0.84 mSv (to physicists). The estimated doses fall below the recommended annual dose limit. However, the lack of a radiation surveillance program and use of occupational exposure control tools are of concern in both the IC and NM departments. •Dose to staff were studied in nuclear medicine (NM) and interventional cardiology (IC) in Sudan.•In IC procedures, the estimated annual effective doses were: 1.95–2.53 mSv varied.•In NM procedures, the estimated annual effective doses were: 0.19–0.92 mSv varied.•Doses are below the annual dose limit but occupational exposure control tools are lacking.•The data are important in promoting radiation protection good practices at workplaces.

    M. Alkhorayef, Y. Hamza, A. Sulieman, I. Salih, E. Babikir, D.A. Bradley (2019)Effective dose and radiation risk estimation in certain paediatric renal imaging procedures, In: Radiation physics and chemistry (Oxford, England : 1993)154pp. 64-68 Elsevier Ltd

    Renal imaging (scintigraphy, intravenous urography (IVU) and computed tomography urography (CTU)) are non-invasive procedures that provide information essential in the diagnosis and treatment of renal disorders. The importance of these procedures notwithstanding, radiation exposure to the different tissues and organs could result in diverse reaction possibilities of varying severity. Accordingly, patient dose measurement of such exposures represent an essential step in seeking radiation dose optimization. Present study seeks to quantify effective doses for paediatric patients undergoing renal scintigraphy, IVU and CTU procedures using technetium-99m-diethylene-triamine-pentaacetic acid. Patients population consist of 116 patients (68 boys and 48 girls) were investigated using an Orbiter 37 single-head gamma camera, a digital imaging system and a dual-slice CT detector unit. Patient effective doses were estimated, administered activity ranging between 37.0 and 129.5 MBq per procedure. The mean effective dose and range (in mSv) for renal scintigraphy, CT Urography and IVU procedures were 1.0, 0.98 and 0.6 mSv per procedure respectively. The associated radiation risk estimates per procedure range between 80 and 130 cancers per one million procedures. Patients undergoing renal scintigraphy and CTU procedures received comparable doses such that if CT parameters are optimized this then allows the referring physician to consider the best diagnostic outcome regardless of modality selected. •Dose to paediatric patients undergoing radiographic renal imaging calculated.•Effective dose & radiation risk estimated for 99mTc (DTPA), CT urography, intravenous urography.•The least dose to paediatric patients found to be from intravenous urography.•Patients undergoing renal scintigraphy and CTU procedures found to receive comparable doses.

    M. Alkhorayef, A. Sulieman, H. Barakat, H.I. Al-Mohammed, K. Theodorou, C. Kappas, D. Bradley (2021)Urethrographic examinations: Patient and staff exposures and associated radiobiological risks, In: Saudi journal of biological sciences28(1)pp. 35-39 Elsevier B.V

    Medical exposure of the general population due to radiological investigations is the foremost source of all artificial ionising radiation. Here, we focus on a particular diagnostic radiological procedure, as only limited data are published with regard to radiation measurements during urethrograpic imaging. Specifically, this work seeks to estimate patient and occupational effective doses during urethrographic procedures at three radiology hospitals. Both staff and patient X-ray exposure levels were calculated in terms of entrance surface air kerma (ESAK), obtained by means of lithium fluoride thermoluminescent dosimeters (TLD-100(LiF:Mg:Cu.P)) for 243 urethrographic examinations. Patient radiation effective doses per procedure were estimated using conversion factors obtained from the use of Public Health England computer software. In units of mGy, the median and range of ESAK per examination were found to be 10.8 (3.6–26.2), 7.0 (0.2–32.3), and 24.3 (9.0–32.0) in Hospitals A, B, and C, respectively. The overall mean and range of staff doses (in µGy) were found to be 310 (4.0–1750) per procedure. With the exception of hospital C, the present evaluations of radiation dose have been found to be similar to those of previously published research. The wide range of patient and staff doses illustrate the need for radiation dose optimisation.

    A Sulieman, F Mayhoub, H Salah Ibrahim, H Omer, M Alkhorayef, Fouad A Abolaban, H Al-Mohammed, M U Khandaker, D A Bradley (2021)EVALUATION OF ANNUAL RADIATION EXPOSURE OF STAFF IN A CARDIAC CATHETERIZATION DEPARTMENT IN SAUDI ARABIA, In: Radiation protection dosimetry195(3-4)pp. 314-318 Oxford University Press

    Abstract The objective of this study is to estimate the annual effective dose for cardiologists and nurses by measuring Hp(10) and Hp(0.07) during cardiac catheterization procedures. A total of 16 staffs members were working in interventional cardiology during 1 year at a tertiary hospital. The occupational dose was measured using calibrated thermo-luminescent dosemeters (TLD-100, LiF:Mg,Ti). The overall mean and range of the annual Hp(10) and Hp(0.07) (mSv) for cardiologists were 3.7 (0.13–14.5) and 3.2 (0.21–14.7), respectively. Cardiologists were frequently exposed to higher doses compared with nurses and technologists. The exposure showed wide variations, which depend on occupation and workload. Staff is adhered to radiation protection guidelines regarding shielding the trunk, thyroid shield, thus appropriately protected. Lens dose measurement is recommended to ensure that dose limit is not exceeded.

    M. Alkhorayef, A. Sulieman, B. Alonazi, M. Alnaaimi, M. Alduaij, D. Bradley (2019)Estimation of radiation-induced cataract and cancer risks during routine CT head procedures, In: Radiation physics and chemistry (Oxford, England : 1993)155pp. 65-68 Elsevier

    Eye lenses lie within the radiation field during computed tomography (CT) procedures of the brain. Therefore, patients are at risk of forming eye lens opacity when exposures exceed the threshold for such onset. The purpose of this study was to estimate the eye lens equivalent and radiation effective doses during CT procedures of the brain, facial bones, and paranasal sinuses. A total of 85 patients were examined using a 16-detector CT machine. The organ and surface dose received by specific radiosensitive organs was carried out using software from the National Radiological Protection Board (NRPB). The overall mean patient doses were as follows: CTDIvol, 45.7 +/- 15.6 mGy for brain; and 7.6 mSv for the eye lens. The mean eye lens equivalent dose per CT procedure was 11.5 mSv, 4.5 mSv, and 6.7 mSv for the brain, paranasal sinuses, and facial bones, respectively. The radiation risk per procedure equates to 1 cancer case per 11 x 10(-3) procedures. The study shows there to be great need for improving the imaging protocol and for continuous training of staff. Dose reduction techniques in brain CT are required, eye lens irradiations potentially generating lens opacities.

    M. Alkhorayef, Fareed H. Mayhoub, Hassan Salah, A. Sulieman, H.I. Al-Mohammed, M. Almuwannis, C. Kappas, D.A. Bradley (2020)Assessment of occupational exposure and radiation risks in nuclear medicine departments, In: Radiation physics and chemistry (Oxford, England : 1993)170 Elsevier Ltd

    During the preparation of radioisotopes, during their administration and during patient imaging nuclear medicine personnel are routinely exposed to ionising radiation. With radiation risks increasing with dose, safety assessment is required in seeking to ensure practice complies with international guidelines and dose limits. A particular aim herein is to measure staff exposures during certain molecular imaging procedures including through use of positron emission tomography with computed tomography (PET/CT) and single photon emission computed tomography (SPECT) procedures. Over a one-year period occupational doses were monitored for 30 nuclear medicine personnel at King Faisal Specialist Hospital and Research Center (KFSH&RC) in Riyadh. Dose equivalent values were measured in terms of Hp (10) (deep dose) and Hp (0.07) (skin dose), extremity doses also being measured via ring dosimeters. The measurements were made using calibrated thermoluminescent dosimeters, type LiF:Mg, Ti (TLD-100). In mSv, the respective mean annual dose and range for Hp (10), Hp (0.07) and extremities were 3.05 ± 2.1 (0.23–0.91), 3.15 ± 2.2 (0.1–9.1) and 28.25 (0.1–298.0). In all cases, extremity dose values were well below the annual dose limit (500 mSv). Nevertheless, with personnel doses varying significantly, careful assessment of working conditions is recommended in efforts to ensure occupational exposures remain below annual dose limits. •Occupational doses were monitored for 30 nuclear medicine personnel over one year using thermoluminescent dosimeters.•The dose was quantified in terms of Hp (10) and Hp (0.07) and extremity doses.•Occupational doses were below the annual dose limits for whole body and extremities.•Careful assessment of working conditions are recommended in seeking to reduce gender differences in occupational exposures.

    M. Alkhorayef, A. Sulieman, E. Babikir, E. Daar, M. Alnaaimi, M. Alduaij, D. Bradley (2018)Patient Exposure during Fluoroscopy-guided Pacemaker Implantation Procedures, In: Applied radiation and isotopes138pp. 14-17 Elsevier Ltd

    A pacemaker, which is used for heart resynchronization with electrical impulses, is used to manage many clinical conditions. Recently, the frequency of pacemaker implantation procedures has increased to more than 50% worldwide. During this procedure, patients can be exposed to excessive radiation exposure. Wide range of doses has been reported in previous studies, suggesting that optimization of this procedure has not been fulfilled yet. The current study evaluated patient radiation exposure during cardiac pacemaker procedures and quantified the patient effective dose. A total of 145 procedures were performed for five pacemaker procedures (VVI, VVIR, VVD, VVDR, and DDDR) at two hospitals. Patient doses were measured using the kerma-area product meter. Effective doses were estimated using software based on Monte Carlo simulation from the National Radiological Protection Board (NRPB, now The Health Protection Agency). The effective dose values were used to estimate cancer risk from the pacemaker procedure. Patient demographic data and exposure parameters for fluoroscopy and radiography were quantified. The mean patient doses ± SD per procedure (Gy cm2) for VVI, VVIR, VVD, VVDR, and DDDR were 1.52 ± 0.13 (1.43–1.61), 3.28 ± 2.34 (0.29–8.73), 3.04 ± 1.67 (1.57–4.86), 6.04 ± 2.326 3.29–8.58), and 8.8 ± 3.6 (4.5–26.20), respectively. The overall patient effective dose was 1.1 mSv per procedure. It is obvious that the DDDR procedure exposed patients to the highest radiation dose. Patient dose variation can be attributed to procedure type, exposure parameter settings, and fluoroscopy time. The results of this study showed that patient doses during different pacemaker procedures are lower compared to previous reported values. Patient risk from pacemaker procedure is low, compared to other cardiac interventional procedures. Patients' exposures were mainly influenced by the type of procedures and the clinical indication. •Radiation dose measured for pediatric patients undergoing cardiac pacemaker procedure.•Entrance surface air kerma (ESAK) were measured using Kerma Area Product meter.•The patient dose during pacemaker implantation depends upon procedure type and type of fluoroscopic equipment.•Patient dose is within the safety limit and the risk from pacemaker procedures is low.

    M. Alkhorayef, A. Sulieman, M. Mohamed-Ahmed, H. I. Al-Mohammed, N. Alkhomashi, A. K. Sam, D. A. Bradley (2018)Staff and ambient radiation dose resulting from therapeutic nuclear medicine procedures, In: Applied radiation and isotopes141pp. 270-274 Elsevier

    With associated cure rates in excess of 90%, targeted 1311 radioactive iodine therapy has clearly improved thyroid cancer survival. Thus said, potential radiation risks to staff represent a particular concern, current stud) seeking to determine the radiation exposure of staff from 1311 patients during hospitalization, also estimating accumulated dose and related risk to staff during preparation of the radioactive iodine. In present study made over the three-month period 1st February to 1st May 2017, a total of 69 patient treatments were investigated (comprising a cohort of 46 females and 23 males), this being a patient treatment load typically reflective of the workload at the particular centre for such treatments. The patients were administered sodium iodide I-131, retained in capsules containing activities ranging from 370 to 5550 MBq at the time of calibration, radioiodine activity depends on many factors such as gender, clinical indication, body mass index and age. The staff radiation dose arising from each patient treatment was measured on three consecutive days subsequent to capsule administration. In units of mu Sv, the mean and dose -rates range at distances from the patients of 5 cm, 1 m and 2 m were 209 +/- 73 (165-294), 6.8 +/- 2 (5.3-9.5) and 0.9 +/- 0.3 (0.7-1.2). The annual dose (also measured in units of mu Sv), based on annual records of doses, for medical physicists, technologists and nurses were 604, 680 and 1000 mu Sv respectively. In regard to current practice and workload, staff exposures were all found to be below the annual dose limit for radiation workers.

    Zubair H. Tarif, Adebiyi Oresegun, Auwal Abubakar, Azmi Basaif, Hafiz M. Zin, Kan Yeep Choo, Siti A. Ibrahim, Hairul Azhar Abdul-Rashid, David A. Bradley (2022)Time-Resolved Radioluminescence Dosimetry Applications and the Influence of Ge Dopants In Silica Optical Fiber Scintillators, In: Quantum beam science6(2) Mdpi

    The quality of treatment delivery as prescribed in radiotherapy is exceptionally important. One element that helps provide quality assurance is the ability to carry out time-resolved radiotherapy dose measurements. Reports on doped silica optical fibers scintillators using radioluminescence (RL) based radiotherapy dosimetry have indicated merits, especially regarding robustness, versatility, wide dynamic range, and high spatial resolution. Topping the list is the ability to provide time-resolved measurements, alluding to pulse-by-pulse dosimetry. For effective time-resolved dose measurements, high temporal resolution is enabled by high-speed electronics and scintillator material offering sufficiently fast rise and decay time. In the present work, we examine the influence of Ge doping on the RL response of Ge-doped silica optical fiber scintillators. We particularly look at the size of the Ge-doped core relative to the fiber diameter, and its associated effects as it is adjusted from single-mode fiber geometry to a large core-to-cladding ratio structure. The primary objective is to produce a structure that facilitates short decay times with a sufficiently large yield for time-resolved dosimetry. RL characterization was carried out using a high-energy clinical X-ray beam (6 MV), delivered by an Elekta Synergy linear accelerator located at the Advanced Medical and Dental Institute, Universiti Sains Malaysia (USM). The Ge-doped silica optical fiber scintillator samples, fabricated using chemical vapor deposition methods, comprised of large core and small core optical fiber scintillators with high and low core-to-cladding ratios, respectively. Accordingly, these samples having different Ge-dopant contents offer distinct numbers of defects in the amorphous silica network. Responses were recorded for six dose-rates (between 35 MU/min and 590 MU/min), using a photomultiplier tube setup with the photon-counting circuit capable of gating time as small as 1 mu s. The samples showed linear RL response, with differing memory and afterglow effects depending on its geometry. Samples with a large core-to-cladding ratio showed a relatively short decay time (

    Siti Nurasiah Mat Nawi, Mayeen Uddin Khandaker, D. A. Bradley, S. F. Abdul Sani, K. S. Al-mugren (2021)Characterization of a promising luminescence-based graphite radiation dosimeter, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier

    Characterization has been undertaken of the thermoluminescence (TL) properties of 0.3 mm polymer pencil lead graphite (PPLG). For 60Co gamma irradiation doses from 0.5 Gy up to 20 Gy readout data have been taken at different heating rates, from 2 to 15 degrees C s-1, linear TL responses with radiation dose being found, also with a greater degree of sensitivity at the lowest dose. Estimation has been made of the principal trap parameters of the PPLG, use being made of the variable heating rate method via the Hoogenstraaten, Booth - Bohun - Parfianovitch and Two Point Two Heating Rate techniques. Among the trap parameters are included the order of kinetics, activation energy, the frequency factor, and the initial concentration of trapped electrons. Also determined are relations that allow estimation of the temperature lag between the heating element and that of the sample. The stability of TL signal has been examined at peak temperatures with the lifetime of the TL glow peak calculated. Structural alterations of the irradiated PPLGs have been observed via Raman and Photoluminescence (PL) spectroscopy, also via X-ray diffraction (XRD), providing information on physical parameters relating to the defects participating in the luminescence process. The results indicate 0.3 mm PPLG to offer promising potential as a new generation of radiation dosimeter, including for medical radiation applications.

    Mayeen Uddin Khandaker, S. N. Mat Nawi, S. E. Lam, S. F. Abdul Sani, Mohammad Amirul Islam, M. A. Islam, K. A. Naseer, Hamid Osman, D. A. Bradley (2023)Thermoluminescent characterization and defect studies of graphite-rich media under high dose neutron exposure, In: Applied radiation and isotopes196pp. 110771-110771 Elsevier

    Thermoluminescence (TL) materials have a broad variety of uses in various fields, such as clinical research, individual dosimetry, and environmental dosimetry, amongst others. However, the use of individual neutron dosimetry has been developing more aggressively lately. In this regard, present study establishes a relationship between the neutron dosage and the optical property changes of graphite-rich materials caused by high doses of neutron radiation. This has been done with the intention of developing a novel, graphite-based radiation dosimeter. Herein, the TL yield of commercially graphite-rich materials (i.e. graphite sheet, 2B and HB grade pencils) irradiated by neutron radiation with doses ranging from 250 Gy to 1500 Gy has been investigated. The samples were bombarded with thermal neutrons as well as a negligible amount of gamma rays, from the nuclear reactor TRIGA-II installed at the Bangladesh Atomic Energy Commission. The shape of the glow curves was observed to be independent of the given dosage, with the predominant TL dosimetric peak maintained within the region of 163 degrees C-168 degrees C for each sample. By studying the glow curves of the irradiated samples, some of the most well theoretical models and techniques were used to compute the kinetic parameters such as the order of kinetics (b), activation energy (E) or trap depth, frequency factor (s) or escape probability, and trap lifetime (t). All of the samples were found to have a good linear response over the whole dosage range, with 2B grade of polymer pencil lead graphite (PPLGs) demonstrating a higher level of sensitivity than both HB grade and graphite sheet (GS) samples. Additionally, the level of sensitivity shown by each of them is highest at the lowest dosage that was given, and it decreases as the dose increases. Importantly, the phenomenon of dose-dependent structural modifications and internal annealing of defects has been observed by assessing the area of deconvoluted microRaman spectra of graphite-rich materials in high-frequency areas. This trend is consistent with the cyclical pattern reported in the intensity ratio of defect and graphite modes in previously investigated carbon-rich media. Such recurrent occurrences suggest the idea of employing Raman microspectroscopy as a radiation damage study tool for carbonaceous materials. The excellent responses of the key TL properties of the 2B grade pencil demonstrate its usefulness as a passive radiation dosimeter. As a consequence, the findings suggest that graphiterich materials have the potential to be useful as a low-cost passive radiation dosimeter, with applications in radiotherapy and manufacturing.

    Z. Siti Rozaila, M. U. Khandaker, S. F. Abdul Sani, Siti Norbaini Sabtu, Y. M. Amin, M. J. Maah, D. A. Bradley (2018)Reply to Comment on 'Environmental monitoring through the use of silica-based TLD', In: Journal of radiological protection38(4)pp. 1535-1543 Iop Publishing Ltd
    Sabina Yasmin, Mayeen Uddin Khandaker, Z. Siti Rozaila, Md Abdur Rashid, D. A. Bradley, S. F. Abdul Sani (2020)Thermoluminescence features of commercial glass and retrospective accident dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)168 Elsevier

    Five window glass brands popularly used in Bangladeshi dwellings have been analyzed for retrospective accident dosimetry, being inexpensive, highly effective as a barrier to moisture and naturally transparent at optical wavelengths. In examining their potential for dosimetry, study has been made of the annealing - irradiation - readout steps contributing to characterization of the various key thermoluminescence properties. These include the respective glow curves, relative sensitivity, dose response, energy response, reproducibility and fading. An ERESCO model 200 MF4-RW X-ray machine and a Gammacell-220 Co-60 source was used for sample irradiation, while a Harshaw 3500 TLD reader (USA) supported by WinREMS software was used for TL readouts. Within the gamma-radiation dose range up to 50 Gy, the various TL parameters show Nasir glass (a locally produced glass brand) to offer the most promising performance for retrospective dosimetry. Fading studies indicate the reconstruction of absorbed dose to be possible for periods of up to four weeks post-exposure. Energy dispersive X-ray analysis shows the Z(eff) of the various glass to be in the range 12.5-15.1, closely according with that of TLD-200, a commercial dosimeter used for low-level environmental radiation dosimetry. Present work constitutes the first such study of low-cost commercial glass for doses in the range 10-50 Gy, previous literature relating to doses from 50 Gy up to 20 kGy.

    Siti Nurasiah Mat Nawi, Mayeen Uddin Khandaker, D. A. Bradley, S. F. Abdul Sani, K. S. Almugren, Abdelmoneim Sulieman (2020)Polymer pencil lead graphite for in vivo radiation dosimetry, In: Diamond and related materials106 Elsevier

    This work explores the use of polymer pencil-lead graphite (PPLG) as a novel material for passive radiation dosimetry, analysis including state-of-the-art techniques. The versatility of carbon materials in such applications arises in great part from the strong dependence of their physical properties on the ratio of sp2 (graphite-like) to sp3 (diamond-like) bonds. Investigation has been made of key dosimetric properties of commercially available PPLG, specifically the thermoluminescence (TL) glow curve, dose response, energy dependence, effective atomic number, sensitivity and fading. Four different diameter PPLG rods have been studied, their response to photon irradiations being examined. The PPLGs have been found to provide good linear response within the dose range 10 to 200 Gy, sensitivity increasing inversely with PPLG rod diameter. With a standard deviation < 3%, all samples showed excellent reproducibility. The fading study was also calculated, the stability of TL signal being examined at room temperatures in dark condition. Vibrational spectra of the irradiated PPLGs were determined using a 532 nm laser Raman spectrometer while bulk resistance, an indirect measure of dosimetry, was studied via electrochemical impedance spectroscopy. The various dose response evaluations reveal the 2B hardness polymer pencil-lead to possess favourable dosimetric features, suited to passive sensing of radiation for a range of ionizing radiation applications, medical and sterilizational work included.

    D. A. Bradley, Lam Siok Ee, Siti Nurasiah Mat Nawi, Siti Fairus Abdul Sani, Mayeen Khandaker, Khalid Alzimami, Layal Jambi, Amal Alqhatani (2022)Radiation induced defects in graphite, In: Applied radiation and isotopes182pp. 110141-110141 Elsevier

    The Raman intensity ratio I-D/I-G for: (a) graphite-rich pencil rods irradiated using x-ray doses up to 20 Gy; (b) a restricted view of the I-D/I-G response for the same group of media, limited to x-ray doses of no more than 6 Gy; (c1 and c2) an extended group of graphite-rich media irradiated using Co-60 gamma-rays; (d) a restricted view of the I-D/I-G response for a restricted group of the media shown in (c), with Co-60 gamma-ray doses limited to no more than 20 Gy; (e) 2B graphite-rich pencil rods irradiated using 6 MeV electrons, and: (f) irradiation of a subset of the media by thermal (0.025 eV) neutrons. The fluctuation of I-D/I-G with dose for carbon-rich human hair of nominal diameter 60 mu m is indicated by the dashed line in (c) and (d). The values in parentheses indicate the percentage carbon content and the surface area-to-volume ratio of samples. The data are a re-organisation of that included in the studies of Abdul Sani et al. (2020, Bradley et al. (2019, 2021), Mat Nawi et al. (2021a,b), and Lam et al. (2021) such as to illustrate three prime dependencies, viz. surface to volume ratio, carbon content, and linear energy transfer, LET. (g) and (h) are combination graphs as indicated in the key to each.

    Siti Nurasiah Mat Nawi, S. F. Abdul Sani, M. U. Khandaker, N. M. Ung, K. S. Almugren, F. H. Alkallas, D. A. Bradley (2021)Tailored Ge-doped fibres for passive electron radiotherapy dosimetry (vol 15, e0235053, 2020), In: PloS one16(9) Public Library Science
    K.S. Almugren, S.F. Abdul Sani, R. Wandira, Norfadira Wahib, Z. Siti Rozaila, M.U. Khandaker, D.A. Bradley (2019)Thermoluminescence response of X-ray irradiated commercial chalk, In: Applied radiation and isotopes151pp. 102-110 Elsevier Ltd

    Present research concerns the TL signal stored in chalk of the variety commercially available for writing on blackboards. Samples of this have been subjected to x-ray irradiation, the key dosimetric parameters investigated including dose and energy response, sensitivity, fading and glow curve analysis. Three types of chalk have been investigated, each in five different colours. The samples were annealed at 323 K prior to irradiation. For all three chalk types and all five colours, the dose response has been found linear over the investigated dose range, 0–9 Gy. Regardless of type or colour, photoelectric energy dependency is apparent at the low energy end down to the lowest investigated accelerating potential of 30 kV. Crayola (Yellow) has shown the greatest TL sensitivity, thus selection has been made to limit further analysis to this medium alone, specifically in respect of glow curve and fading study. In addition, elemental compositional and structural change characterizations were made for the same medium, utilizing Energy Dispersive X-Ray (EDX) and Raman spectroscopy, respectively. •Thermoluminescence characterisation of commercial chalk under X-ray exposure, producing a linear dose response.•Mass energy response of all chalks sample dominate at 30 keV X-ray irradiation.•Main elemental compositions in chalk are found to be carbon, oxygen, calcium and sulphur.•Alteration in structural damage upon exposure to ionising radiation using Raman spectroscopy.

    S.F. Abdul Sani, S.S. Ismail, K.S. Almugren, M.U. Khandaker, D.A. Bradley (2020)Dosimetric utility of structural changes in gamma irradiated graphite-rich pencils, In: Radiation physics and chemistry (Oxford, England : 1993)171 Elsevier Ltd

    9B and H grade carbon-based pencil (carbon concentrations approaching 81 and 62 wt respectively %) have been investigated for radiotherapy dosimetry applications, offering low dependence on photon energy and near soft tissue effective atomic number. Comparison has been made with highly oriented pyrolytic graphite (HOPG), a pure and ordered synthetic form of graphite. The samples were exposed to 60Co gamma ray doses from 0 to 20 Gy (encompassing the range of doses utilized in fractionated radiotherapy), structural interaction alterations resulting from the radiation doses being observed via Raman and Photoluminescence (PL) spectroscopy and X-ray diffraction (XRD). Among the most prominent features to be observed in Raman spectra are the so-called G and D peaks, appearing at 1578 cm−1 and 1348 cm−1 respectively. The intensity ratio ID/IG was used for further characterization of the dose-dependent defects produced in the graphitic materials. From PL measurement, sample average energy band gap values are observed to be within the region 1.114–1.116 eV, being considered direct bandgap-like semiconductors. The characteristic XRD crystal plane Miller index (002) peak was observed in order to calculate the atomic spacing, lattice constant and the degree of structural order of the irradiated samples. •Carbon-based pencil of 9B and H irradiated with 60Co gamma in comparison to HOPG.•Raman and PL spectroscopy and XRD techniques were used to investigate the microstructure and defects.•H-type pencil possesses potential application for radiation therapy application.

    Ashwitha Nancy D'Souza, K. Sharmila, M.I. Sayyed, H.M. Somshekarappa, Mayeen Uddin Khandaker, D.A. Bradley, Sudha D. Kamath (2021)Gamma ray shielding and thermoluminescence investigation of bismuth added heavy metal oxide glasses, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier Ltd

    Nowadays, as a replacement for lead which is a toxic element, bismuth glasses are explored extensively due to their higher density for radiation attenuation applications. This work is an attempt to portray the radiation shielding and thermoluminescence response of bismuth in the borosilicate glasses of composition (60-x) B2O3– 20SiO2- xBi2O3– 12ZnO– 8BaO with x = 0, 2, 4, 6, 8, 10 and 12 mol% coded as ZBiB glasses. The estimation of theoretical values of gamma ray shielding parameters with 137Cs gamma source such as mass attenuation co-efficient, effective atomic number, half value layer and mean free path was carried out using Photon Shielding and Dosimetry software and compared with experimental results. The data naturally showed high attenuation values for ZBiB-12 glass. Higher bismuth samples were observed to possess dark brown colour and opaque nature. The applicability of such glasses for gamma dosimetry using thermoluminescence (TL) property was also examined by irradiating the glasses with 3 kGy of 1.25 MeV gamma radiation from 60Co source. The radiation created defect centers by breaking Zn–O, Bi–O, Si–O, B–O and Si–O–B bonds resulting in high intensity TL peaks. The role of Bi as thermoluminescence quenching agents has been evaluated in the present investigation. Computer Glow Curve Deconvolution was done for the TL curves to get the information regarding trapped charges such as activation energy, half-life and frequency factor. Among the high bismuth incorporated glasses, ZBiB-8 sample exhibited comparably higher TL intensity at 576.1 K with half-life of 23 years. •MAC values at 662 keV of gamma energy were comparable with the theoretical values.•For 3 kGy dose, there was a major reduction in TL intensity upon adding Bi3+ ions.•ZBiB-8 glass was found to be more suitable for TLD application.

    Matthew Tikpangi Kolo, Mayeen Uddin Khandaker, Yusoff Mohd Amin, Wan Hasiah Binti Abdullah, David A. Bradley, Khalid S. Alzimami (2018)Assessment of health risk due to the exposure of heavy metals in soil around mega coal-fired cement factory in Nigeria, In: Results in physics11pp. 755-762 Elsevier B.V

    Mobilization and dispersion of potentially toxic elements into the atmosphere and human environment due to industrial and anthropogenic activities have been associated with significant human health challenges. In this investigation, 20 surface soil samples collected around a coal-fired cement factory in northeast Nigeria were analysed for their heavy metal (Cr, Pb, Ni, Cu, Zn and Mn) concentrations using inductively coupled plasma mass spectrometry. The results showed that mean concentrations of heavy metals, except for Cr were lower than their normal backgrounds (Cr = 76.44 > 64 mg kg−1, Pb = 19.32 

    Sabina Yasmin, Bijoy Sonker Barua, Mayeen Uddin Khandaker, Faruque-Uz-Zaman Chowdhury, Md. Abdur Rashid, David A. Bradley, Michael Adekunle Olatunji, Masud Kamal (2018)Studies of ionizing radiation shielding effectiveness of silica-based commercial glasses used in Bangladeshi dwellings, In: Results in physics9pp. 541-549 Elsevier B.V

    •Silica-based commercial glasses were studied for ionizing radiation effectiveness.•59–1332 keV energies of photon beams were used to obtain various interaction properties.•Glass sample ‘Rider’ from China shows aptness to be used as shielding material. Following the rapid growing economy, the Bangladeshi dwellers are replacing their traditional (mud-, bamboo-, and wood-based) houses to modern multistoried buildings, where different types of glasses are being used as decorative as well as structural materials due to their various advantageous properties. In this study, we inquire the protective and dosimetric capability of commercial glasses for ionizing radiation. Four branded glass samples (PHP-Bangladesh, Osmania-Bangladesh, Nasir-Bangladesh, and Rider-China) of same thickness and color but different elemental weight fractions were analyzed for shielding and dosimetric properties. The chemical composition of the studied material was evaluated by EDX technique. A well-shielded HPGe γ-ray spectrometer combined with associated electronics was used to evaluate the attenuation coefficients of the studied materials for 59 keV, 661 keV, 1173 keV and 1332 keV photon energies. A number of shielding parameters- half value layer (HVL), radiation protection efficiency (RPE) and effective atomic number (Zeff) were also evaluated. The data were compared with the available literature (where applicable) to understand its shielding capability relative to the standard materials such as lead. Among the studied brands, Rider (China) shows relatively better indices to be used as ionizing radiation shielding material. The obtained, Zeff of the studied glass samples showed comparable values to the TLD-200 dosimeter, thus considered suitable for environmental radiation monitoring purposes.

    Md Salah Uddin Afsar, Mohammad Rashed Iqbal Faruque, Md Bellal Hossain, Mohammad Tariqul Islam, Mayeen Uddin Khandaker, D.A. Bradley, Jamel Nebhen (2022)Tuning fork-hammer shaped perfect metamaterial absorber for C-band applications, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    The new compact octagonal split ring resonator with octagonal close ring resonator-based tuning fork-hammer-shaped metamaterial is a perfect metamaterial absorber (PMA) for C-band application. It is a new arrangement of two octagonal ring resonators with tuning fork-hammer shaped metal strips that are fabricated using FR-4 dielectric material. The numerical results obtained from the Computer Simulation Technology (CST) microwave studio exhibited dual resonance peaks at 4.34 GHz and 5.35 GHz with the absorption of 99.98% and 98.31%, respectively for transverse electric (TE) mode. The obtained numerical results were also authenticated using the high-frequency structure simulator (HFSS) simulator, an equivalent circuit model which shows a very insignificant amount of variation. Agilent N5227 Vector Network Analyzer was also used for measurement in this study. A slight variation at all peak points was observed when the simulation and measurement data were compared. Absorption individualities were also analysed using different polarisation angles and incident angles for TE mode. The projected absorber demonstrated near unity absorptions up to 30° polarisation angle and 60° wide incident angle. The proposed design was optimised using different types of parametric studies such as unit cell configurations, split gap, and width of the octagonal ring resonator. This C-band absorber is frequently used in satellite communication band, defence, security, and stealth coating equipment. •A new compact tuning fork-hammer shape PMA for C-band application.•The PMA cover dual absorption frequencies as 4.34 GHz (99.98%), and 5.35 GHz (98.31%).•The proposed PMA offers unity absorption with a simple configuration.•The developed PMA is a highly efficient which is easy to implement.•The PMA apply for satellite communication, defense, security and stealth technology.

    Nissren Tamam, Abdelmoneim Sulieman, Hiba Omer, Hind Toufig, Mohammed Alsaadi, Hassan Salah, Essam H. Mattar, Mayeen Uddin Khandaker, D.A. Bradley (2022)Assessment of breast dose and cancer risk for young females during CT chest and abdomen examinations, In: Applied radiation and isotopes190pp. 110452-110452 Elsevier Ltd

    CT scanning deliver much higher radiation doses than planar radiological procedures, which puts patients to high risks. This study measures and evaluates patient doses during chest and abdomen computed tomography procedures. Particular attention is given to measuring the dose to the equivalent breast (mSv) and to estimate the associated risks of breast cancer to young female patients (15–35 years). Data was obtained from standard examinations from three hospitals. The measured values of CT dose indexes, CTDI (mGy) as well as exposure-related parameters were used for assessment. Breast and effective doses were extrapolated using a software. The results showed remarkable variations of the mean organ equivalent doses for similar CT examinations in the studied hospitals. This could be attributed to the variation in CT scanning imaging technique, and clinical indications. The average effective dose to the chest was 7.9 mSv (2.3–47.0 mSv) and for the abdomen the mean dose was 6.6 mSv, ranging from (3.3–27 mSv). The breast received equivalent doses from chest and abdomen procedures as follows: 10.2 (1.6–33 mSv) and 10.1(2.3–19 mS) Sv respectively. Each procedure yielded high risks of breast cancer for young females. Implementation of accurate referral criteria is recommended to avoid unnecessary breast radiation exposure. •Breast radiation doses for young females were evaluated during CT chest and abdomen procedures.•CT chest and abdomen procedures yielded high risks of breast cancer for young females.•Breast doses varied from 1.6 to 33 mSv during chest CT procedure.•Proper justification and optimization are recommended to save young females from potential radiogenic risks.

    Mohamed Youssef Mohamed Hanfi, Masoud Salah Masoud, M. I. Sayyed, Mayeen Uddin Khandaker, Mohammed Rashed Iqbal Faruque, D. A. Bradley, Mostafa Yuness Abdelfatah Mostafa (2021)The presence of radioactive heavy minerals in prospecting trenches and concomitant occupational exposure, In: PloS one16(3)pp. e0249329-e0249329 Public Library Science

    Uranium, perhaps the most strategically important component of heavy minerals, finds particular significance in the nuclear industry. In prospecting trenches, the radioactivity of U-238 and Th-232 provides a good signature of the presence of heavy minerals. In the work herein, the activity concentrations of several key primordial radionuclides (U-238, Th-232, and K-40) were measured in prospecting trenches (each of the latter being of approximately the same geometry and physical situation). All of these are located in the Seila area of the South Eastern desert of Egypt. A recently introduced industry standard, the portable hand-held RS-230 BGO gamma-ray spectrometer (1024 channels) was employed in the study. Based on the measured data, the trenches were classified as either non-regulated (U activity less than 1000 Bq kg(-1)) or regulated (with U-238 activity more than 1000 Bq kg(-1)). Several radiological hazard parameters were calculated, statistical analysis also being performed to examine correlations between the origins of the radionuclides and their influence on the calculated values. While the radioactivity and hazard parameters exceed United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) guided limits, the mean annual effective doses of 0.49 and 1.4 mSv y(-1) in non-regulated and regulated trenches respectively remain well below the International Commission on Radiological Protection (ICRP) recommended 20 mSv/y maximum occupational limit. This investigation reveals that the studied area contains high uranium content, suitable for extraction of U-minerals for use in the nuclear fuel cycle.

    M.I. Sayyed, Ali Askin, M.H.M. Zaid, S.F. Olukotun, Mayeen Uddin Khandaker, Daria I. Tishkevich, D.A. Bradley (2021)Radiation shielding and mechanical properties of Bi2O3–Na2O–TiO2–ZnO–TeO2 glass system, In: Radiation physics and chemistry (Oxford, England : 1993)186 Elsevier Ltd

    Recently, heavy metal oxides (HMO) based glass systems attracted great attention to the scientific community to be used as an alternative to the conventional lead, lead composites and concrete based materials for protection of harmful radiation. In this work, we report the role of Bi2O3 on the mechanical and radiation shielding properties of Bi2O3–ZnO–TiO2–Na2O–TeO2 glass system as well as its mechanical behaviour. The mechanical properties of the glasses were calculated using Makishima-Mackenzie model and different shielding factors have been calculated using Monte Carlo simulation via Geant4 code and also using Phy-X software. The mechanical properties based on Makishima-Mackenzie model depend on the values of packing density (Vi) and dissociation energy (Gi) of the oxide constituents. The simulated values of the mass attenuation coefficient showed a good agreement between both approaches. The mass attenuation coefficient (MAC) at 0.284 MeV of the glass with 5 mol% of Bi2O3 is equal to 0.2083 cm2/g, at 0.662 MeV its equal to 0.0785 cm2/g, while at 1.33 MeV, its MAC is 0.0501 cm2/g. The transmitted percentage of the photons through the proposed glasses was found to rise with increasing the energy of the photon, while decreasing with rising the thickness of the glass sample. The transmission factor (TF) revealed that the greater the thickness of the glass, the lower the TF, and the better the shield. Also, the radiation protection efficiency of the glasses was enhanced with the addition of the Bi2O3. The glass sample with composition of 15Bi2O3–10ZnO–5TiO2–5Na2O–65TeO2 possesses the highest effective atomic number among the studied compositions and showed the lowest half value layer. From the obtained data, Bi2O3 seems to be a strong candidate for enhancing the gamma radiation attenuation factors in the bismuth-based tellurite glasses. •The MAC at 0.284 MeV of the glass with 5 mol% of Bi2O3 is equal to 0.2083 cm2/g.•The RPE of the glasses was enhanced with the addition of the Bi2O3.•The transmitted percentage of the photons decreases with increasing the thickness.

    M.I. Sayyed, M. Kh Hamad, M.H.A Mhareb, Recep Kurtulus, Nidal Dwaikat, Marwa Saleh, Mohamed Elsafi, Malaa M. Taki, Taner Kavas, Kh.A. Ziq, Mayeen Uddin Khandaker, D.A. Bradley (2022)Assessment of radiation attenuation properties for novel alloys: An experimental approach, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    In the current investigation, the conventional solid-state reaction was used to fabricate new Cr-based alloys (CrTe, CrTe0.95Sb0.05, CrTe0.90Sb0.10 and CrTe0.80Sb0.20). For these alloys, we experimentally explored the gamma ray shielding performance. Gamma radiation attenuation for the four prepared alloys were performed using “transmission method” with photons emitted from the sources (Ho-166 and Cs-137). The experimental results were compared with the theoretical data generated from Phy-X software, and a good agreement between both methods was reported. Moreover, the radiation protection efficiency for the prepared alloys was reported between 0.184 and 0.81 MeV. The half value layer (HVL) value for the four prepared alloys was also computed, and we discussed the variation of the HVL with the chemical composition for these alloys. The linear attenuation coefficient (LAC) results demonstrated that replacing CrTe alloy with Sb causes in enhancing LAC value in all photon energies. For instance, at 0.662 MeV, LAC is found as 0.330, 0.337, 0.368, and 0.387 1/cm for Sb0 to Sb20 series, respectively. •Four alloy samples were fabricated by solid state reactions.•The radiation shielding features were explored experimentally.•The alloys nature were investigated by using X-ray diffractions.•Adding Sb to CrTe alloys is helpful in enhancing the shielding features of the alloys.

    Edwin Humphrey Uguru, Mohd Faiq Bin Ahmad Sapli, S.F. Abdul Sani, Mayeen Uddin Khandaker, Mohamad Hairie Rabir, Julia Abdul Karim, D.A. Bradley (2021)Impact of weight percent gadolinium and the number of its fuel rods on the neutronic and safety parameters, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier Ltd

    Control of neutron multiplication in a nuclear reactor is fundamental in achieving stable reactor power. The present study has sought to determine the impact of gadolinium weight percent (w/o) in respect of the number of fuel rods on the neutronic and safety parameters of (Th, U)O2 fuel in a Westinghouse small modular reactor. The MCNPX 2.7 integrated with CINDER90 fuel depletion code was used. The results show that the k-infinite and reactivity swing peak decrease with increasing gadolinium weight percent, with the highest and lowest k-infinite recorded in the fuel assembly containing zero (0) and 12 w/o, respectively. The largest and lowest reactivity swing curve occurs in the fuel assembly with 3.6 and 12 w/o at ~15 and ~35 GWd/THM, respectively. It shows that the impact of gadolinium w/o and the number of fuel rods on k-infinite follow similar trend. Conversely, the reactivity swing curve is observed to flatten with increasing gadolinium w/o but increases with increase in the number of gadolinium burnable absorber fuel rods. These phenomenological variations suggest that flat reactivity swing and power control can be achieved within 9.2–12 w/o gadolinium although not without economic penalty on fuel utilisation. •The reactivity swing-peak decreases with gadolinium weight percent.•Reactivity swing curve increases with increasing number of gadolinium fuel rods.•Large gadolinium weight percent impacts negatively on FTC.•Large gadolinium weight percent impacts positively on MTC.•Gadolinium is not economically viable at and above 12 w/o.

    Abdelmoneim Sulieman, Nissren Tamam, Mayeen Uddin Khandaker, D.A. Bradley, R. Padovani (2021)Radiation exposure management techniques during endoscopic retrograde cholangio-pancreatography procedures, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    One the most complicated gastrointestinal procedures, endoscopic retrograde cholangio-pancreatography (ERCP) uses fluoroscopy guidance of an endoscope to diagnose and treat hepatobiliary system pathologies. As is true of all approved interventional radiology, it is justified by the massive benefit that it is capable of delivering, one which for the patient far outweighs the risks from radiation exposure. Nevertheless, for both patients and staff there is a need to minimize the risk of carcinogenesis and the potential for tissue reactions. Recent concern has been shown in regard to radiation induced eye lens opacifications and cataract, most particularly for the members of staff who during their regular theatre practice are in closest contact with the patient. Therefore, optimum balance between benefit versus radiation risk is required. This study reviews patient and staff dose during ERCP procedures, also seeking to provide comprehensive data regarding radiation exposure management techniques. Patient and staff doses depend on the operators, equipment and patient related factors, benefitting from awareness and experience in respect of radiation protection techniques and the availability of modern fluoroscopic equipment. It is apparent that in high workload departments, staff doses to eye lens may exceed the limits on annual exposure. •Previous studies in patients and occupational dosimetry had been studies.•Patients and staff remain constant regardless of the X ray technology development.•ERCP is safe during pregnancy for patients and pregnant workers.•It is apparent that in high workload departments, staff doses to eye lens may exceed the limits on annual exposure.•Lack of training and monitoring services in gastroenterology department are frequently reported.

    Mayeen Uddin Khandaker, Hauwau Kulu Shuaibu, Farida Assghir Amar Alklabi, Khalid S Alzimami, D A Bradley (2019)Study of Primordial 226Ra, 228Ra, and 40K Concentrations in Dietary Palm Dates and Concomitant Radiological Risk, In: Health physics (1958)116(6)pp. 789-798

    The presence of natural radionuclides in the food chain point to a need to assess concentration levels and concomitant radiological risk. Highly popular and forming a staple part of the diet in North Africa, the Arabian Peninsula, and West Asia, palm dates growing naturally there have even greater marketability than simple satisfaction of domestic demand, the palm dates representing a valuable export item. Accurate knowledge of the levels of natural radioactivity in the fruit is thus of importance. In this study, using high-purity germanium gamma-ray spectrometry, quantification has been made of natural radionuclide concentrations in imported dates originating from Iran, Saudi Arabia, and Tunisia. Sample analyses reveal respective mean activity concentrations of 1.4 ± 0.3, 0.8 ± 0.4, and 186 ± 9 Bq kg dry weight for Ra, Ra, and K. For each nuclide, the mean concentration varies little between the dates of the three represented regions. The estimated committed effective dose resulting from the consumption of date fruits for a typical adult was found to be 29.9 μSv y, well below the global internal dose of 290 μSv y assessed by the United Nations Scientific Committee on the Effects of Atomic Radiation to be due to food and water intake. Similarly, the excess lifetime cancer risk due to naturally occurring radioactive material exposure via date fruit consumption is seen to be below the International Commission on Radiological Protection cancer risk factor of 2.5 × 10 based on the additional annual dose limit of 1 mSv for a member of the general public. The results show no significant uptake in the analyzed date fruits.

    Mayeen Uddin Khandaker, Nurul 'Adillah Binti Heffny, Yusoff Mohd Amin, D.A. Bradley (2019)Elevated concentration of radioactive potassium in edible algae cultivated in Malaysian seas and estimation of ingestion dose to humans, In: Algal research (Amsterdam)38 Elsevier B.V

    Although the various benefits of seaweeds are well recognised, potential health hazards are much less well researched, as an instance the possible presence of concentrated levels of natural radionuclides. In present work the concentrations of natural radionuclides in seaweed cultivated in Malaysian seas are assessed using conventional HPGe γ-ray spectrometry. An edible species of seaweed has been collected from several seaweed farms located along coasts of the Andaman and South China Sea. Activity concentrations of 226Ra, 228Ra and 40K in samples collected from Langkawi are observed to be greater than those from Sabah, while 40K radioactivity levels (2.2E3 ± 100 – 3.8E3 ± 180 Bq kg−1) in all samples are noted to be well above the world average value of between 400 and 580 Bq kg−1. The estimated amount of total potassium is in the range 68 – 120 g (kg of seaweed)−1 and 53–106 g kg−1 obtained via ICP-OES, which are in line with data for New Zealand seaweed of between 43.7 and 123 g kg−1. The estimated total effective dose of 84 μSv·y−1 is lower compared to a global internal dose of 290 μSv·y−1 as reported by UNSCEAR. Accordingly, the mean cancer risk from such consumption was also estimated to be slightly lower (1.92 × 10−3) compared to the ICRP cancer risk factor of 2.5 × 10−3 based on the additional annual dose limit of 1 mSv for a member of the general public, which gives an annual mortality probability of 10−5 (1 in 100,000; ICRP, 1991). Although posing a low risk health hazard, periodic monitoring of natural radioactivity in foodstuff remains important in seeking to ensure the radiological safety of the public. •Activity concentrations of 226Ra, 232Th and 40K in edible seaweeds were determined.•Radioactivity of 40K in all samples is well above the world average value.•Committed effective dose and lifetime cancer risk for humans were estimated.•Seaweed consumption with the current rate posing a low risk to public health

    R. S. Omar, S. Hashim, D. A. Bradley, M. K. A. Karim, I. Kobayashi, A. B. A. Kadir, A. Hashim (2022)Al2O3:C and LiF: Mg, Ti characterisations at 100-150 kV energy range for computed tomography dose measurement, In: Radiation physics and chemistry (Oxford, England : 1993)199 Elsevier

    Performance characterisation has been carried out of nanoDotTM OSLDs and TLD-100TM, validating their use for diagnostic x-ray dose profile assessments. Investigations include optical annealing, signal depletion, signal fading, dose-response, sensitivity, and energy dependence. Both dosimeter types were exposed using the Con-stant Potential Industrial X-ray (Model Philips MG 165) in Standard Radiation Qualities (RQT) procedure located in Nuclear Malaysia, Bangi. OSLD annealing using a 14 W compact fluorescent lamp showed an average signal loss of-93% as a result of 60 min of illumination. For dosimetric signal depletion, screened nanoDotTM OSLDs gave rise to the most favorable performance, with a mean signal loss of 1.0% per reading. In respect of signal fading, similar favorable performance was found for the screened nanoDotTM OSLDs, after a stabilisation period of 11-12 days post-irradiation, the average reading decreased by-1% over a further 17 days. For doses up to 500 mGy the TLD-100TM and screened nanoDotTM OSLDs both provide a highly linear response, with a regression coefficient of 0.999 in both cases. Linear energy dependence was found for RQT spectra from 100 to 150 kV.

    F. Moradi, M. U. Khandaker, S. F. Abdul Sani, E. H. Uguru, A. Sulieman, D. A. Bradley (2021)Feasibility study of a minibeam collimator design for a Co-60 gamma irradiator, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier

    Recently much attention has been paid to microbeam and minibeam irradiations, present interest focusing on their use in study of the behaviour of single cells, groups of cells, also their application in spatially fractionated radiotherapy. Synchrotrons are the most common source for microbeam radiotherapy (MRT), albeit limited in access and typically offering photon energies very much lower than familiar in the practice of conventional radiotherapy. In this study of feasibility, the design has been investigated of a collimator coupled to a conventional Co-60 gamma-irradiator sample chamber to produce a minibeam. MCNPX code Monte Carlo simulations were used to model a Gammacell 220 Co-60 irradiator with lead and tungsten collimators. The dose profile was evaluated in the absence and presence of the collimator, seeking to optimize collimator design. The results pertain to specific shapes of lead and tungsten collimators producing narrow (millimeter dimension) beams, sufficient in thickness but yet still fitting within the sample chamber, with a peak-to-valley dose ratio (PVDR) greater than 15. The beam size can be tailored with modification in the size of the perforated part, the collimator optimized to minimize the dose-rate at points away from the collimator centre. However the dose-rate at the centre is reduced to between 2 to 20% of that in the absence of collimator. The findings of this study encourage the development of minibeam collimator for gamma irradiators, useful for preclinical minibeam radiotherapy research in centres with little or no access to other appropriate sources.

    S. Yasmin, M. U. Khandaker, D. A. Bradley, Hamid Osman, Amjad Alyahyawi, M. I. Sayyed, M. R. I. Faruque, K. A. Naseer, Abubakr M. Idris (2022)The efficacy of various thicknesses of float glasses for protection of gamma-radiation, In: Radiation physics and chemistry (Oxford, England : 1993)199 Elsevier

    Recognizing the availability and low cost of marketable glasses, this study evaluates the radiation protection efficacy of various thicknesses of float glasses used in Bangladeshi dwellings. Numerous float glasses differing in widths (2.5 mm, 3.2 mm, 5.0 mm, 5.9 mm, 7.9 mm, and 10 mm) and produced by the Nasir glass industry in Bangladesh are studied herein. In this regard, at energies 59 keV, 661 keV, 1173 keV, and 1332 keV, the major radiation protection attributes such as effective atomic number, narrow-beam absorption coefficients, mass absorption coefficients, half-value layer, and radiation protection efficiency have been evaluated. The incident and transmitted photon intensity have been measured via a well-shielded HPGe gamma-ray detector accompanied by obligatory electronics. The values of narrow-beam absorption coefficients of the studied glass specimens show a decreasing trend of SNG-1 > SNG-2 > SNG-3 > SNG-4 > SNG-5 > SNG-6. It has been perceived that the effective atomic number of the glass specimen is 13.6, which shows good aspirants of TLD-200 (Z(eff) = 16.3) as well as bone tissue equivalence. Based on the half-value layer (HVL) study, the lowest and highest thickness glass specimens SNG-1 (2.5 mm) and SNG-6 (10 mm) have lessened the incident radiation by 7% and 20%, respectively. On the other hand, the specimen SNG-6 has offered almost 2.5 times higher radiation protection efficacy than the specimen SNG-1 studied herein.

    Sabina Yasmin, Mayeen Uddin Khandaker, S. N. Mat Nawi, S. F. Abdul Sani, D. A. Bradley, M. A. Islam (2021)The potential of decorative building materials (marble) for retrospective thermoluminescence dosimetry, In: Applied radiation and isotopes175pp. 109782-109782 Elsevier

    Among the various types of decorative materials used in Bangladeshi dwellings, the marble/marble stone is one of the most common ones that used largely for enhancing the beauty and/or aristocracy of the dwelling environment. In this study, the most commonly used, six types of marble stones, have been analyzed for retrospective accident dosimetry. With the interest of characterizing several key thermoluminescence properties to examine their potentiality for dosimetry, annealing - irradiation - readout steps have been done chronologically which comprises the analysis of glow curves, relative sensitivity, dose dependence, repeatability and fading. Considering the various TL parameters, marble 'Carrara' imported from Italy present relatively better capability for reconstruction of radiation dose in the dose range of 10-50 Gy. From fading result, it is clear that for reconstruction of absorbed dose up to four weeks of post exposure, the marble 'Carrara' is found to be the most reliable media among the studied marble types. The Z(eff) values for the various marble samples are found to be in the range of 13.65-19.12, comparing favorably in replace of TLD-200 (Z(eff) = 16.3) which can be used for low-level environmental radiation dosimetry. Present work constitutes the first study to investigate the potentials of marble stone for reconstruction of absorbed dose in the range of 10-50 Gy dose.

    A. Sulieman, M.Z. Mahmoud, O. Serhan, B. Alonazi, M. Alkhorayef, K. Alzimami, D. Bradley (2018)CT examination effective doses in Saudi Arabia, In: Applied radiation and isotopes141pp. 261-265 Elsevier Ltd

    Patient effective doses and the associated radiation risks arising from particular computed tomography (CT) imaging procedures are assessed. The objectives of this research are to measure radiation doses for patients and to quantify the radiogenic risks from CT brain and chest procedures. Patient data were collected from five calibrated CT modality machines in Saudi Arabia. The results are from a study of a total of 60 patients examined during CT procedures using the calibrated CT units. For CT brain and chest, the mean patient effective doses were 1.9 mSv (with a range of 0.6–2.5 mSv) and 7.4 mSv (with a range of 0.5–34.8 mSv) respectively. The radiogenic risk to patients ranged from between 10−5 and 10−4 per procedure. With 65% of the CT procedure cases diagnosed as normal, this prompts re-evaluation of the referral criteria. The establishment of diagnostic reference levels (DRL) and implementation of radiation dose optimisation measures would further help reduce doses to optimal values. •Radiation dose survey for patients undergoing CT brain and chest examinations in Saudi Arabia.•Breast dose found to be high in CT chest examination, clear justification criteria being crucial.•Wide discrepancy between patient doses underlines need for establishing dose reference levels.•Dose delivered to patients found to be greater than reported in previous studies.

    A.N. Edam, M.R. Fornasier, M. De Denaro, A. Sulieman, M. Alkhorayef, D.A. Bradley (2018)Quality control in dual head gamma-cameras: Comparison between methods and software used for image analysis, In: Applied radiation and isotopes141pp. 288-291 Elsevier Ltd

    Patient radiation dose and image quality are primary issues in the conduct of nuclear medicine (NM) procedures. A range of protocols are currently used in image acquisition and analysis of quality control (QC) tests, with National Electrical Manufacturers Association (NEMA) methods and protocols widely accepted in providing an accurate description, measurement and report of γ-camera performance parameters. However, no standard software is available for image analysis. Present study compares vendor QC software analysis and three types of software freely downloadable from the internet: NMQC, NM Toolkit and ImageJ-NM Toolkit software. These were used for image analysis of QC tests of γ-cameras based on NEMA protocols including non-uniformity evaluation. Ten non-uniformity QC images were obtained using a dual head γ-camera installed in Trieste General Hospital and then analyzed. Excel analysis was used as the baseline calculation for the non-uniformity test according to NEMA procedures. The results of non-uniformity analysis showed good agreement between the independent types of software and Excel calculations (the average differences were 0.3%, 2.9%, 1.3% and 1.6% for the Useful Field of View (UFOV) integral, UFOV differential, Central Field of View (CFOV) integral and CFOV differential, respectively), while significant differences were detected following analysis using the company QC software when compared with Excel analysis (the average differences were 14.6%, 20.7%, 25.7% and 31.9% for the UFOV integral, UFOV differential, CFOV integral and CFOV differential, respectively). Compared to use of Excel calculations use of NMQC software was found to be in close accord. Variation in results obtained using the three types of software and γ-camera QC software was due to the use of different pixel sizes. It is important to conduct independent analyses tests in addition to using the vendor QC software in order to determine the differences between values. •Comparison of vendor QC analysis software with that freely downloadable from the internet.•Software for image analysis based on NEMA protocols including non-uniformity evaluation.•Significant differences between Excel and vendor software due to different pixel sizes used in analysis.

    H Salah, Mohammad Rabbaa, Mohammad Abuljoud, E Babikir, M Alkhorayef, N Tamam, Dahlang Tahir, A Sulieman, D A Bradley (2023)Paediatric effective radiation doses during brain computed tomography angiography procedure, In: Applied radiation and isotopes192pp. 110610-110610
    R.S. Omar, S. Hashim, S.K. Ghoshal, D.A. Bradley, N.D. Shariff (2021)Radiation dose assessment of 64 Multi-Slices Computed Tomography scanner, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    This paper reports the performance and dose assessment of the X-ray generator and CT dosimetry of 64 Multi-Slices Computed Tomography (MSCT) scanners operating under the CT scanning condition during the axial mode. The dose was evaluated at various parameters (kV, mA, and exposure time) using a multi-function detector (Unfors) and nanoDot™ optically stimulated luminescence dosimeters (OSLDs). The measured values of the weighted CT Dose Index (CTDIw) were obtained using a 100 mm standard pencil beam ion chamber and nanoDot™ OSLDs operated on a cylindrical PMMA phantom of 160 mm long (160 mm-diameter head and 320 mm-diameter). The CTDIw values were specified either according to the central axis or 10 mm from the 4 outer edges of the phantom. The two sizes of the phantoms based on the measurements of the CTDIw of the CT scanner were recorded. The values of CTDIw were calculated to determine the performance of the CT X-ray generator. The deviation accuracy of the tube voltage was ±5 kV or ±5% (whichever is greater) whereas the accuracy of the tube potential (mA) was ±10%. The execution of the CT dosimetry steps was shown to ensure patient safety with reduced risk during the improper selection of the dose. It is established that the measured CTDIw values for the radiation dosage under exceptional CT scanning conditions in the axial mode may enable to meet the manufacturer's guidelines (

    Edwin Humphrey Uguru, S. F. Abdul Sani, Mayeen Uddin Khandaker, Mohamad Hairie Rabir, F. Moradi, John Elom Ekpe, D. A. Bradley (2021)The impact of gadolinium on the reactor production of Sm-153, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier

    Radioisotopes represent major sources of ionizing radiation, not least for use in medical applications, brachytherapy and nuclear medicine included. In this, the nuclear reactor is the main source of beta-gamma emitting isotopes, an example product being Sm-153 used in the treatment of pain arising from bone metastases. Present analysis relates to the potential of gadolinium neutron capture reaction, its impact on reactor production of radioisotopes and the proliferation resistant potential of thorium fuel cycle. A comparative analysis has been made of the impact of gadolinium on the production of Sm-153 by UO2 and (Th, U) O-2 fuels in a Westinghouse small modular reactor. Five fuel assemblies were investigated: one containing no gadolinium, the other four containing 16, 24, 34 or 44 gadolinium fuel rods. The code Monte Carlo N-Particle eXtended (MCNPX) integrated with the CINDER90 burn-up code was used for calculations. In the production of Sm-153 the same trend is followed for the fuels containing gadolinium, increasing significantly with the number of gadolinium fuel rods. Zero production results from fuel assemblies without gadolinium. The concentration of Sm-153 increases significantly with burn-up, indicating that gadolinium has a positive impact on the production of Sm-153.

    Recep Kurtulus, M.I. Sayyed, Taner Kavas, K.A. Mahmoud, O.L. Tashlykov, Mayeen Uddin Khandaker, D.A. Bradley (2021)A lanthanum-barium-borovanadate glass containing Bi2O3 for radiation shielding applications, In: Radiation physics and chemistry (Oxford, England : 1993)186 Elsevier Ltd

    Radiation shielding materials are of prime importance for weighing the benefit-to-risk of ionizing radiation. In this perspective, a lanthanum-barium-borovanadate (BVBL) glass containing varying amounts of bismuth oxide (Bi2O3) is studied in this work. The glass composition of 5La2O3–10BaO-(65-x)B2O3–20V2O5-xBi2O3 where x: 0, 3, 6, 9, 12, 15 mol% has been purposed, and thus six different glass series with BVBL0 to BVBL15 coded were investigated for the physical, mechanical, and radiation shielding features. Physical property calculations revealed that the glass density increase from 3.1685 to 4.1345 g cm-3 with the insertion of Bi2O3 from 0 to 15 mol%. Furthermore, mechanical properties in terms of the Mackenzie-Makishima model demonstrated that Young's, bulk, shear, and longitudinal moduli were reduced following the concentration of Bi2O3. In particular, the BVBL0 sample showed the best mechanical moduli amongst others. Radiation shielding competencies were ascertained by using Phy-X/PSD and Monte Carlo N-Particle Transport Code (MCNP-5). The theoretical computations via Phy-X/PSD clearly indicated that the linear attenuation coefficient (LAC) showed enhanced characteristics with the increasing content of Bi2O3. Based upon the determined LAC, the other essential parameters such as half-value layer (HVL), effective atomic number (Zeff), and transmission factor (TF) were also assessed. Moreover, the MCNP-5 simulation demonstrated that the BVBL15 sample provided the best radiation attenuation compared to the undoped BVBL0. Moreover, both Phy-X/PSD and MCNP5 studies displayed good agreement with each other. Overall, we concluded that Bi2O3 seems to be a strong candidate for improving radiation attenuation coefficients in the BVBL glass system. •The ascending doping rate in Bi2O3 leads to the increment of the overall ρglass from 3.1685 to 4.1345 g/cm3.•The highest LAC values are relevant to the BVBL15.•MCNP-5 and Phy-X/PSD computations revealed a good agreement with each other.•Mechanical moduli decreased as the Bi2O3 content increased.

    D. A. Bradley, H. T. Zubair, A. Oresegun, G. T. Louay, H. A. Abdul-Rashid, N. M. Ung, Khalid S. Alzimami (2019)Towards the development of doped silica radioluminescence dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)154pp. 46-52 Elsevier

    We discuss recent investigations by members of this group concerning the performance of P-doped silica for radioluminescence-based dosimetry. Comparisons are made against that of an in-house developed Ge-doped silica system and carbon-doped alumina (Al2O3:C). The readout obtained for dose-rate evaluations herein make use of the phenomena of radioluminescence (RL), which is enabled by defects giving rise to electron trapping. We have compared the RL signal originating from our Ge- and P-doped silica optical fibres (doping of Ge and P being the primary sources of defects in the silica media) and commercial nanoDot Al2O3:C dosimeters, the RL signal being guided through PMMA optical fibres to obtain real-time measurements. In regard to afterglow, the P-doped fibre retains the least memory of prior irradiation, favouring its use in real-time evaluations in the use of pulsed beams, improving upon the performance of the Ge-doped fibre.

    Mayeen Uddin Khandaker, Khandoker Asaduzzaman, Abdullah Fadil Bin Sulaiman, D.A. Bradley, Matthew Omoniyi Isinkaye (2018)Elevated concentrations of naturally occurring radionuclides in heavy mineral-rich beach sands of Langkawi Island, Malaysia, In: Marine pollution bulletin127pp. 654-663 Elsevier Ltd

    Study is made of the radioactivity in the beach sands of Langkawi island, a well-known tourist destination. Investigation is made of the relative presence of the naturally occurring radionuclide 40K and the natural-series indicator radionuclides 226Ra and 232Th, the gamma radiation exposure also being estimated. Sample quantities of black and white sand were collected for gamma ray spectrometry, yielding activity concentration in black sands of 226Ra, 232Th and 40K from 451±9 to 2411±65Bqkg−1 (mean of 1478Bqkg−1); 232±4 to 1272±35Bqkg−1 (mean of 718Bqkg−1) and 61±6 to 136±7Bqkg−1 (mean of 103Bqkg−1) respectively. Conversely, in white sands the respective values for 226Ra and 232Th were appreciably lower, at 8.3±0.5 to 13.7±1.4Bqkg−1 (mean of 9.8Bqkg−1) and 4.5±0.7 to 9.4±1.0Bqkg−1 (mean of 5.9Bqkg−1); 40K activities differed insubstantially from that in black sands, at 85±4 to 133±7Bqkg−1 with a mean of 102Bqkg−1. The mean activity concentrations of 226Ra and 232Th in black sands are comparable with that of high background areas elsewhere in the world. The heavy minerals content gives rise to elevated 226Ra and 232Th activity concentrations in all of black sand samples. Evaluation of the various radiological risk parameters points to values which in some cases could be in excess of recommendations providing for safe living and working. Statistical analysis examines correlations between the origins of the radionuclides, also identifying and classifying the radiological parameters. Present results may help to form an interest in rare-earth resources for the electronics industry, power generation and the viability of nuclear fuels cycle resources. •Reference data of NORMs in beach sand of Langkawi Island is reported.•All radiological hazard indices for heavy mineral rich beach sand are found higher than the permissible limit.•Presence of monazite rich black sand is the reason for enrichment of UNat and ThNat.•Measured data may form an interest in rare-earth resources for electronics industry and nuclear fuels cycle resources.

    Aya Ahmed, Mohammed Ali, H. Salah, Rufida Elbushra Eisa, Hazem Mohieldin, Hiba Omer, A. Sulieman, N. Tamam, D.A. Bradley (2022)Evaluation of uptake values of FDG: Body surface area Vs. body weight correction, In: Radiation physics and chemistry (Oxford, England : 1993)201 Elsevier Ltd

    The uptake of Fluorine-18 fluoro-deoxy-glucose (18F-FDG) in tumors is assessed using the Standardized Uptake Values (SUVs). These values are usually normalized for the body weight of the patients (SUVbw). However, reported literature revealed an overestimation of uptake in obese patients who suffer from higher body fat content with low uptake of the 18F-FDG. Normalization of 18F-FDG uptake using body surface area (SUVbsa) may present a solution to overestimating uptake. The current study aims to evaluate uptake values of FDG in the tumor versus liver using two standardizing parameters: weight and area. Data for liver and tumor uptake were collected from 40 patients who underwent FDG-PET scans. Regarding uptake for the liver, the standardization using body weight, SUVbw, was calculated as tissue concentration over activity injected per body weight. Using surface area, SUVbsa used activity injected per surface area rather than weigh in the denominator. The correlation was performed to determine the association between the factors of age, body mass index (BMI), and liver SUVmax. The SUVbsa ranged between 0.79 and 5.8, and SUVbw ranged between 3.11 and 28.36. The range, as well as the standard deviation, were by far more in SUVbw than SUVbsa and the independence of the values on the size of patients proves that the latter is a preferable standardization method. •The uptake of 18F-FDG in tumors is assessed using the Standardized Uptake Values (SUVs).•Data for uptake in the liver and tumour were collected from 40 patients underwent FDG-PET scans.•Standardization using surface area, SUVbsa used activity injected per surface area rather than weigh in the denominator.•Normalization of 18F-FDG uptake using SUVbsa present a solution to the overestimation of uptake.

    H. Salah, H. Al-Mohammed, F. H. Mayhoub, A. Sulieman, M. Alkhorayef, Fouad A. Abolaban, Mayeen Uddin Khandaker, D. A. Bradley (2021)ASSESSMENT OF PATIENT'S RADIATION EXPOSURES RESULTED FROM PET/CT F-18-FCH AND (68)GA-PSMA PROCEDURES, In: Radiation protection dosimetry195(3-4)pp. 349-354 Oxford Univ Press

    This study has sought to evaluate patient exposures during the course of particular diagnostic positron emission tomography and computed tomography (PET/CT) techniques. A total of 73 patients were examined using two types of radiopharmaceutical: F-18-fluorocholine (FCH, 48 patients) and Ga-68-prostate-specific membrane antigen (PSMA, 25 patients). The mean and range of administered activity (AA) in MBq, and effective dose (mSv) for FCH were 314.4 +/- 61.6 (462.5-216.8) and 5.9 +/- 1.2 (8.8-4.11), respectively. Quoted in the same set of units, the mean and range of AA and effective dose for Ga-68-PSMA were 179.3 +/- 92.3 (603.1-115.1) and 17.9 +/- 9.2 (60.3-11.5). Patient effective doses from F-18-FCH being a factor of two greater than the dose resulting from Ga-68-PSMA PET/CT procedures. CT accounts for some 84 and 23% for F-18-FCH and Ga-68-PSMA procedures, accordingly CT acquisition parameter optimization is recommended. Patient doses have been found to be slightly greater than previous studies.

    Jane K. L. Teh, David A. A. Bradley, Woo Teck Ang, Kok Lay Teo, Jack Bee Chook, Kee Huong Lai, Suat-Cheng Peh (2022)Insights into Controlling the Spread of COVID-19: A Study Inspired by Seven of the Earliest Vaccinated Countries, In: Journal of environmental and public health2022pp. 1-14 Hindawi Publishing Group

    Background. The aim of the study is to derive deeper insights into the control of the spread of COVID-19 during the second half of 2021, from seven countries that are among the earliest to have accelerated the deployment of COVID-19 vaccines. Methodology. This study used data from the Global COVID-19 Index and Google COVID-19 Community Mobility Reports. Data was extracted on the 5(th) of each month from July to December 2021. Seven countries were selected-United Kingdom, United States of America, Israel, Canada, France, Italy, and Austria. The sample comprised number of new cases, hospitalisations, ICU admissions and deaths due to COVID-19, government stringency measures, partial and full vaccination coverage, and changes in human mobility. Principal component analysis was conducted, and the results were interpreted and visualized through 2-dimensional and 3-dimensional plots to reveal the systematic patterns of the data. Results. The first three principal components captured around 77.3% of variance in the data. The first component was driven by the spread of COVID-19 (31.6%), the second by mobility activities (transit, retail, and recreational) (24.3%), whereas the third by vaccination coverage, workplace-related mobility, and government stringency measures (21.4%). Visualizations showed lower or moderate levels of severity in COVID-19 during this period for most countries. By contrast, the surge in the USA was more severe especially in September 2021. Human mobility activities peaked in September for most countries and then receded in the following months as more stringent government measures were imposed, and countries began to grapple with a surge in COVID-19 cases. Conclusion. This study delineated the spread of COVID-19, human mobility patterns, widespread vaccination coverage, and government stringency measures on the overall control of COVID-19. While at least moderate levels of stringency measures are needed, high vaccine coverage is particularly important in curbing the spread of this disease.

    Mohammed Ali, Suhaib Alameen, Alaa Bashir, Aya Saeed, Hassan Salah, Nissren Tamam, Abdelmoneim Sulieman, D. A. Bradley (2022)Estimate of effective dose for adult patients from nuclear medicine examinations in Sudan, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier

    Artificial radiation is the primary radiogenic risk source to the general population. Medical field has been growing in Sudan. This study aims to estimate effective doses for adult patients from nuclear medicine examinations. The study involved 685 patients from five different hospitals in Sudan. In total, 300, 196, and 189 patients underwent renal, thyroid, and bone scans. All procedures were carried out using the Tc-99m radionuclide. Effective dose has been estimated using computer software depending on conductive activity. The results show that dose information for patients from thyroid, renal, and bone scan, for thyroid scan the patients' age was 42.82 +/- 16.46 years, the patient's weight 68.58 +/- 12.82 kg, the activity 4.75 +/- 0.543 mCi and the effective dose for thyroid was 2.28 +/- 0.26 mSv. For renal scan, the patients' age 45.19 +/- 16.36 years, the weight 65.96 +/- 13.78 kg, the activity 5.21 +/- 1.166 mCi, and the effective dose 0.94 +/- 0.211 mSv. For a bone scan, the patients' age was 57.59 +/- 14.92 years, the patient's weight was 69.48 +/- 13.71 kg, the activity 19.96 +/- 2.11 mCi, and the effective dose for bone was 4.208 +/- 0.443 mSv. The study revealed that the administered activity is independent of patient weight. Patients received unjustified exposure due to the high amount of administered activity. Implementation of national guidelines is necessary to improve the practice and patient safety.

    Mayeen Uddin Khandaker, D.A. Bradley, Hamid Osman, M.I. Sayyed, A. Sulieman, M.R.I. Faruque, K.A. Naseer, Abubakr M. Idris (2022)The significance of nuclear data in the production of radionuclides for theranostic/therapeutic applications, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    Accurate knowledge of nuclear data are important for the production of radionuclides to be used in medical applications. This study outlines the availability and scarcity of standardized nuclear data for the production of promising medical radionuclides, focusing on the accelerator route. The data are considered for the radionuclides that have the potentials to be used in theranostic applications, i.e., dual-mode imaging and targeted radionuclide therapy. The present status of nuclear data, current trends in nuclear data publication and further requirements for the production of promising theranostic/therapeutic radionuclides by using accelerators are discussed. This work is expected to provide a basic understanding on the accelerator-based production of promising radionuclides in no carrier added form for theranostic medical applications. •A brief review on production routes for NCA radionuclides has been presented.•We outlined the availability and scarcity of standardized nuclear data for the production of promising radionuclides.•The presented information may help in the development of novel therapeutic/theranostic radionuclides.

    Van Minh Truong, Xuan Hai Nguyen, Dong Vu Cao, Thanh Tai Duong, Dinh Khang Pham, Hoang Phuc Nguyen, Huu Tiep Nguyen, Tien Hung Dinh, Van Hiep Cao, Van Chuan Phan, Hiba Omer, Abdelmoneim Sulieman, David A. Bradleyj, Ngoc Anh Nguyen, David Andrew Bradley (2022)Determination of Fe and Tb concentrations in geological and environmental samples using the instrumental neutron activation analysis method combined with the gamma - gamma coincidence technique, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier

    The instrumental neutron activation analysis (INAA) method was combined with the gamma - gamma coincidence technique to measure Iron (Fe) and Terbium (Tb) concentrations in geological (Montana II Soil) and environmental (Coal Fly Ash) standard materials. The measured concentrations, which agree well with the corresponding certified values, are compared with those obtained from the traditional INAA method. It is demonstrated that employing the gamma - gamma coincidence technique slightly improves the accuracy of the analysis. Furthermore, the coincidence technique enhances the detection limits of Tb by similar to 4.5 and similar to 5.5 times in environmental and geological samples, respectively, but has almost no enhancement in those of Fe. The gamma - gamma coincidence technique therefore does not always promote the analysis quality of the INAA method, but it is effective for analyzing elements whose characteristic gamma rays sustain a high Compton background and/or are overlapped with other gamma rays.

    D.A. Bradley, Lam Siok Ee, Siti Nurasiah Mat Nawi, Siti Fairus Abdul Sani, Mayeen Khandaker, Khalid Alzimami, Layal Jambi (2021)Graphite sheets in study of radiation dosimetry and associated investigations of damage, In: Applied radiation and isotopes174pp. 109769-109769 Elsevier Ltd

    Present work builds upon prior investigations concerning the novel use of graphite-rich polymer pencil-lead for passive radiation dosimetry. Working with photon-mediated interactions at levels of dose familiar in radiotherapy, exploratory investigations have now been made using graphite produced commercially in the form of 50 μm thick sheets. Focusing on the relationship between absorbed radiation energy and induced material changes, investigations have been made of thermo- and photoluminescence dose dependence, also of alterations in Raman spectroscopic features. Photoluminescence studies have focused on the degree of structural order of the samples when exposed to incident MeV energy gamma-radiation, supported by crystallite size evaluations. The results are consistent and evident of structural alterations, radiation-driven thermal annealing also being observed. The results, supportive of previous TL, Raman and photoluminescence studies, are readily understood to arise from irradiation changes occurring at the microscopic level. Notwithstanding the non-linearities observed in the conduct of Raman and photoluminescence studies there is clear potential for applications in use of the defect-dependent methods herein, providing sensitive detection of radiation damage in graphite and from it dose determination. Most specifically, the readily available thin graphite sheets can provide the basis of a low-cost yet highly effective system for studies of radiation-driven changes in carbon (and/or carbon based composites), also as a dosimetric probe of skin dose, its atomic number closely matching with the effective atomic number of soft tissues.

    Mayeen Uddin Khandaker, Kotaro Nagatsu, Katsuyuki Minegishi, Ming-Rong Zhang, Amir R. Jalilian, D. A. Bradley (2020)Cyclotron production of no carrier added Re-186g radionuclide for theranostic applications, In: Applied radiation and isotopes166 Elsevier

    Re-186g (T-1/2 = 3.7183 d, E-(beta)mean(-)= 346.7 keV, I-(beta)mean(-) = 92.59%), a mixed beta and gamma-emitter shows great potential for use in theranostic applications. The dominant Re-185(n,gamma) route, via use of a nuclear reactor, provides 1(86g)Re in carrier added form with low specific activity, while cyclotrons offer no carrier-added (NCA) high specific activity production of 186 gRe. However, to be able to select the best possible nuclear reaction and to optimize the production route via the use of a cyclotron, information on the excitation function for the reaction of interest as well as for the competing reactions is necessary. Accordingly, we have conducted a detailed study of the excitation functions for W-nat(d, x) reactions in seeking optimized parameters for the NCA production of 186 gRe. Noting a discrepancy among the experimental data, we made an evaluation of the available literature, finally selecting optimum parameters for the production of Re-186g via the W-186(d,2n) Re-186 reaction. These beam parameters were then used for batch production of Re-186g by irradiating an enriched W-186 metallic powder target, followed by a subsequent automated chemical separation process. The preliminary results show 98.1% radionuclidic purity of Re-186g at 8 h subsequent to the End of Bombardment (EOB), offering the potential for use in clinical applications.

    Janatul Madinah Wahabi, Noor Zati Hani Abu Hanifah, Suhairul Hashim, D.A. Bradley (2022)Modified irradiation technique for transfusable blood using a clinical linear accelerator, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    Whole blood irradiation prior to blood transfusion mitigates the risk of Transfusion Associated Graft versus Host Disease (TA-GvHD) to the receiver. This study aimed to improve dose homogeneity, also to benefit from a faster technique and a simplified blood irradiation workflow. An acrylic box accommodating eight units of blood has been fabricated, build-up material being used to ensure dose homogeneity. A linear accelerator dose distribution treatment plan for blood bag irradiations has been evaluated, measurement of dose using nanoDot optically stimulated luminescent dosimeters (OSLD) allowing comparison with calculated dose. By using build-up material, dose distribution was within 95%–107% of the prescribed dose. With all eight units of blood accommodated in the box, an irradiation time of 20 min per box has been needed. Compared to a previously adopted procedure, use of the acrylic box and build-up material maintains dose homogeneity, also simplifying the workflow, the technique also being easy to undertake by the operators. •Simple blood irradiation process with improved dosage uniformity between blood bags.•Dose distribution can achieve 95%–107% of the prescribed dose using blood irradiation box and build-materials.•Automation of the procedure will reduce potential errors with the use of OIS.

    M. F. Hassan, W. N. W. A. Rahman, A. B. A. Kadir, N. M. Isa, T. Tominaga, M. Geso, H. Akasaka, D. A. Bradley, N. M. Noor (2018)Fabricated Ge-doped Flat Optical Fibres: Assessing the Thermoluminescence Glow Curves for Proton Beam Irradiation, In: M M Ramli, V C Hong, SSM Isa, N S Ismail, L WeiWen, MFM Fathil (eds.), 4TH ELECTRONIC AND GREEN MATERIALS INTERNATIONAL CONFERENCE 2018 (EGM 2018)2045(1) Amer Inst Physics

    We investigate the fundamental characteristics of thermoluminescence (TL) glow curves on the fabricated 2.3 and 6.0 mol% germanium (Ge) doped flat optical fibres subjected to proton beam irradiation. The novel fabricated flat Ge-doped optical fibres used in this study were manufactured using a modified chemical vapour deposition (MCVD) based technique. TLD-100 dosimeters and commercial optical fibres (CorActive High-Tech Inc., Canada) were employed to allow for comparable TL response of the fabricated flat optical fibres. The proton beam irradiations were carried out using a 150-MeV proton beam energy over the radiation doses in the range from 1 to 5 Gy. A Harshaw (TM) 3500 TLD reader was used to read out the given radiation dose to the samples. The results show that the general structure of the TL glow curve for the fabricated flat optical fibres remains unchanged independently within the investigated radiation dose range. Apparently, the fabricated 2.3 mol% Ge-doped flat optical fibres have the most ideal TL glow curves characteristic, representing a single peak distribution, whereas the double peaks distributions were observed for a 6.0 mol% Ge-doped flat optical fibre. All optical fibres were considerably high glow peak temperatures that suggesting the presence of deep-trapped electrons. This convenient position at relatively high temperature will open the way for such optical fibres to be used not only in proton radiotherapy dosimetry, but also in high temperature and difficult-to-access areas, such as that of nuclear power plants.

    Marzieh Hassanpour, Mehdi Hassanpour, Mohammadreza Rezaie, Eysa Salajegheh, Mohammad Rashed Iqbal Faruque, Mayeen Uddin Khandaker, D.A. Bradley (2022)Studies of the mechanical and neutron shielding features of concrete by incorporation of green additive materials: Experimental and numerical study, In: Radiation physics and chemistry (Oxford, England : 1993)191 Elsevier Ltd

    Concrete is one of the materials with a significant level of application in radiation shielding, especially in nuclear installations. However, the shielding features of concrete may vary depending on the composition of the concrete. In the present study, attempts have been made to assess the effects of the possible addition of two natural additives (hence 'green') - pistachios shell (PS) and date palm leaf (PL), in small dosages, as a partial replacement of conventional sand aggregates - on the neutron shielding properties of concrete mixes. Extensive numerical studies are made with Monte Carlo N-Particle code (MCNP-code) to investigate the influences of additives on neutron shielding performance of the candidate mixes for an assumed spherical geometry. Results are presented in terms of variation of the current transmission rate (CTR) and energy spectrum on assumed irradiation with a neutron beam. After initially comparing the NRS performance of the two materials under study, vis-à-vis four others - Cu, Li, Concrete, and Boron, the neutron shielding performance of concrete mixtures with increasing weight percentages of PS and PL incorporated in them have been assessed through the MCNP code. The results have indicated a general pattern for the neutron shielding with these mixtures, best performances achieved with a higher percentage of these green additives (10–15%). Mechanical strengths of the concrete samples with different weight percentages from 1% to 15% of PS and PL also have been experimentally investigated. The 7- and 28-days compressive strength optimized the concrete sample, however Cl with 1% of addition of PS- additive, has an acceptable, marginally lower compressive strength (6.33% and 6.87% at 7- and 28-days) as compared to the control concrete. Also, the density of the concrete was found to decrease with the increasing incorporation of PL and PS additives. Results thus have indicated that the incorporation of PS and PL additives in concrete can lead to quite enhanced shielding performance against the fast and thermal neutrons. As a result, the PL and PS additive materials may prove as a perfect replacement for expensive boron or enriched boron for neutron shielding application. •Mechanical and radiation shielding properties of concrete with two green additives are evaluated.•Pistachios shell (PS) and date palm leaf (PL) are the two additive materials used herein.•In numerical model, spherical geometry simulated by MCNPX as neutron shielding was studied.•Results indicate that addition of PS and PL leads a better neutron shielding performance.•Both PL and PS have a highest shielding percentage at spherical surfaces of radius >50 cm.

    Entesar Z. Dalah, Ousama Mahdi, Wiam Elshami, Mohamed M. Abuzaid, Leena R. David, Ola A. Mira, Abdulmunhem Obaideen, Hussein M. Elmandi, D. A. Bradley (2018)Occupational doses to cardiologists performing fluoroscopically-guided procedures, In: Radiation physics and chemistry (Oxford, England : 1993)153pp. 21-26 Elsevier

    Interventional cardiologists (ICs) receive the largest radiation dose of any medical specialist working with X-ray techniques. The aim of present study has been to obtain dose estimates received by ICs during fluoroscopically-guided imaging and interventional procedures. TLDs in the form of badges, rings, and chips have been used, measuring H-p(10) and H-p(0.07) as appropriate. During the course of 41 coronary angiography (CAG) cases, 50 percutaneous coronary intervention (PCI) cases and 9 (CAG + PCI) procedures, cardiologist doses to the skin of the hands, upper neck area and to the eyes were assessed. Two-TLD badges were placed at the level of the Pb-composite collar exterior to the shielding, with a further two placed under and two more over the Pb-composite apron. Four chip-form TLDs were positioned above the eyebrows (two for the right- and two for the left eye), and two ring dosimeters were worn on the left and right hands. Cardiologist doses correlated with total fluoroscopy time over the five month period of the survey, the annual effective doses received by the body, eyes, hands and upper trunk area being estimated to be 8.0-, 10.7-, 24.3- and 10.2 mSv respectively, all well below the ICRP recommended equivalent dose limits, indicating well-controlled radiation protection practices.

    Muhammad Zamir Mohyedin, Hafiz Mohd Zin, Suhairul Hashim, David A. Bradley, S. Aldawood, M. Alkhorayef, A. Sulieman, Ahmad Taufek Abdul Rahman (2022)2D and 3D dose analysis of PRESAGE® dosimeter using a prototype 3DmicroHD-OCT imaging system, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    The purpose of this study was to investigate the two dimensional (2D) and three dimensional (3D) radiotherapy dosimetric properties of PRESAGE® dosimeter using an in-house optical computed tomography (OCT) imaging system known as 3DmicroHD-OCT. Dosimetric properties for verification of intensity-modulated radiation therapy (IMRT) treatment technique were studied including dose linearity, dose integration, dose rate dependence and the percentage depth dose analysis. Nine cylindrical PRESAGE® of 5 cm diameter × 5 cm height were irradiated at 6 MV photon beam with different field geometry for the dose range of 0.1–15 Gy. We also irradiated PRESAGE® in the cuvette for UV–Vis analysis for the same dose range to verify the optical density value measured by the 3DmicroHD-OCT imaging system. The irradiation was repeated with EBT film dosimetry for the 2D analysis validation. The study shows that the optical density change increases as dose deposition increases on PRESAGE®, with R2 value better than 0.988. The same response was also recorded when multiple beam was integrated for the dose range investigated. The dose linearity result is consistent with the results obtained from UV–Vis spectrometry. It was also found that the dose rate variation does not affect the optical density change over the dose range investigated. PDD analysis of the PRESAGE® dosimeter investigated shows a good agreement with the ion chamber measurement. In summary, the study shows accurate 3D and 2D measurements of PRESAGE® and EBT film dosimeter were obtained using the 3DmicroHD-OCT imaging system. It shows potential for intensity-modulated radiation therapy (IMRT) treatment verification. •The prototype 3DmicroHD-OCT system provides 3D optical imaging for PRESAGE® dosimeter.•Multidimensional (2D and 3D) dose analysis was validated against EBT film.•The 3D dose integrated is linear from 0.1 to 15 Gy and independent of dose rates.

    N.T. Abahreh, S.F. Abdul Sani, S.S. Ismail, Laura Elizabeth Fernando, N. Tamchek, Julia A. Karim, K.S. Almugren, Nur Adilah Roslan, A.S. Siti Shafiqah, D.A. Bradley (2023)Thermoluminescence yield of neutron irradiated Gd:Mg-Doped silica glass, In: Radiation physics and chemistry (Oxford, England : 1993)202
    V. Kandan, M.F. Hassan, N. Omar, H.K. Shahar, F. Mohamad, M.K. Abdul Karim, S.F. Abdul Sani, D.A. Bradley, N. Mohd Noor (2021)Advanced glow curve analysis of fabricated fibres for various sources of ionizing radiation, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    Determination is made of glow curves attributes of Ge-doped silica fibres fabricated from Ge-doped preforms. In particular interest is in Ge-doped cylindrical (Ge-CF) and Ge-doped flat (Ge-FF). The fabrications are irradiated using various ionizing radiation sources types, protons (150 MeV, 210 MeV), 6 and 10 MV photons, 6 MeV electrons, and 60Co gammas (mean energy 1.25 MeV), all at a constant dose of 5 Gy. The fibres have been fabricated using the MCVD technique, notably with a Ge-CF having a larger core compared to the commercial cylindrical fibres (CF). Using WinGCF software the glow curves have been deconvolved, revealing five contributory glow peaks, evaluation being made of three kinetic parameters: maximum temperature (Tmax), activation energy (Ea) and peak integral (PI). Ge-CF Ea and PI values are found to be greater than those for Ge-FF. Moreover, for Ge-CF, the activation energy for electromagnetic irradiation (gamma photons) achieves a maximum reading at peak number 3 while its PI is found to be the least. The PI for photon irradiation is shown to be greater than that for electron and proton irradiation. For Ge-FF, Ea again achieves its greatest value at peak 3, the PI being maximum at peak 2 and least at peak 3. Particle irradiations are more greatly associated with deeper trapping levels. Additionally, the overall conclusion is that Ge-CF offers superior TL yield to that of Ge-FF. One-way analysis of variance (ANOVA) for the individual peaks shows there to be significant differences in terms of PI and Ea, p 

    A. Sulieman, B. Elhag, M. Alkhorayef, E. Babikir, K. Theodorou, C. Kappas, D. Bradley (2018)Estimation of effective dose and radiation risk in pediatric barium studies procedures, In: Applied radiation and isotopes138pp. 40-44 Elsevier

    The objectives of this study are to assess pediatric radiation exposure in certain barium studies and to quantify the organ and effective doses and radiation risk resultant from patients' irradiation. A total of 69 pediatric barium studies for upper and lower gastrointestinal tract. Patients' radiation dose was quantified in terms of Entrance surface air kerma (ESAKs) using exposure parameters and DosCal software. Organ and effective doses (E) were extrapolated using national Radiological Protection Board software (NRPB-R279). The mean +/- (SD) and the range of patient doses per procedure were 3.7 +/- 0.4 (1.0-13.0) mGy, 7.4 +/- 1.7(5.5-8.0) mGy and 1.4 +/- 0.9 (0.5-3.6) mGy for barium meal, swallow and enema, respectively. The mean effective doses were 0.3 +/- 0.03 (0.08-1.1) mSv, 0.2 +/- 1.6 (0.44-0.7) mSv and 0.3 +/- 0.9 (0.1-0.8) mSv at the same order. The radiation dose were higher compared to previous studies. Therefore, pediatrics are exposed to avoidable radiation exposure. Certain optimization measures are recommended along with establishing national diagnostic reference level (DRL) to reduce the radiation risk.

    Mohamad Annuar Assadat Husain, Suhairul Hashim, Sib Krishna Ghoshal, Mohamad Hairie Rabir, Norasalwa Zakaria, Muhammad Rawi Mohamed Zin, David Bradley (2019)Determination of out-core fuel burnup in TRIGA PUSPATI, In: MALAYSIAN JOURNAL OF FUNDAMENTAL AND APPLIED SCIENCES15(6)pp. 890-894 Penerbit Utm Press

    The investigation was conducted on the out-core neutron flux and burn-up at irradiated fuel stored in TRIGA PUSPATI research reactor tank. This is required to examine whether the thermal and/or fast neutron flux can influence burn-up of the irradiated fuel stored in the same vicinity of the reactor core, the fuel rack being located 1 m above the core. MCNPX code was used to simulate fast and thermal neutron flux for the reactor operating at 750 kW. In this work, the computational model was created using MCNPX version 2.7 with the evaluated nuclear data file for thermal neutron scattering law data (ENDF7) cross-section data library and using a 10 cm x 10 cm x 10 cm mesh model. The results showed that the axial distribution for thermal neutrons occurred at energy lower than 1 x 10-6 MeV. Thermal neutron traveled at the maximum distance of 78 cm due to thermalization by moderator. Based on the maximum distance traveled by the thermal neutron, the thermal neutron did not reach the storage rack located 1 m from the core, hence there was no burn-up occurring at the irradiated fuel since burn-up can only occur in the thermal neutron region. For fast neutron, the axial distribution energy was higher than 1 x 10-6 MeV and traveled more than 158 cm. The reaction time for the fast neutron was too short to result in burn-up due to its fast travel.

    Lorenzo Isolan, Francesco Teodori, Francesca Mariotti, Shakardokht Jafari, David Bradley, Marco Sumini (2020)Sensitivity analysis via adjoint Monte Carlo calculations of plasma focus irradiation of micro-silica beads in phantoms, In: Radiation physics and chemistry (Oxford, England : 1993)176 Elsevier Ltd

    One of the main issues in the analysis of the performances of radiation detectors via Monte Carlo methods is their sensitivity with respect to the various irradiation parameters: source intensity and position, detector effectiveness and sensitivity, etc. In the present work, the capability of a quite new Trueinvivo© micro-silica beads TLD has been analyzed from the point of view of the Monte Carlo modeling of the irradiation process and the possibility of a speed up of the calculations using accurate bias techniques based on the adjoint solution of the transport process. The source considered is a Plasma Focus device explicitly designed for cell cultures or “in vivo” tests. The experimental data and the pure analogic Monte Carlo simulation previously obtained results coming from dosimeters at different depth and positions in a PMMA phantom composed by slabs and built for hosting the TLDs, have been benchmarked with respect to the adjoint bias approach. The results obtained through different biasing techniques, backward particle transport analysis, Weight Windows and a discrete ordinate model solution, show how it is possible to optimize the Monte Carlo calculations with great effectiveness. •Ultra-high dose rate Plasma Focus irradiation of TLD in PMMA phantom.•Sensitivity analysis of Trueinvivo© micro-silica beads via adjoint Monte Carlo.•MCNP simulation biasing and acceleration through importance functions.

    Sabina Yasmin, Mayeen Uddin Khandaker, Bijoy Sonker Barua, Md Nurul Mustafa, Faruque-Uz-Zaman Chowdhury, M. A. Rashid, D. A. Bradley (2019)Ionizing radiation shielding effectiveness of decorative building materials (porcelain and ceramic tiles) used in Bangladeshi dwellings, In: Indoor + built environment28(6)pp. 825-836
    Ardiansyah Ardiansyah, Dahlang Tahir, Heryanto Heryanto, Bidayatul Armynah, Hassan Salah, Abdelmoneim Sulieman, David A. Bradley (2023)Science mapping for concrete composites as radiation shielding: A review, In: Radiation physics and chemistry (Oxford, England : 1993)207 Elsevier Ltd

    This paper provides a comprehensive bibliometric analysis to better understand the evolution of concrete composite as a radiation shielding research from when it was first published in 1949 to October 26, 2022. This study was conducted based on the Scopus database, and the publications analyzed a total of 541 documents. The data in this paper is visualized using the VOSviewer and Tableau to perform bibliometric analysis and scientific mapping. The analysis results show that published documents have continued to increase in recent years and are dominated by articles. Some countries show productivity and influence in their country/region with the broadest range of partners. This study presents the most contributed journals and the most frequently cited documents. In addition, keyword analysis was carried out to find the hotspots on this research topic. This paper helps scholars to understand the evolution of concrete composite as a radiation shielding research from a bibliometric perspective and inspires them to develop new concrete composite with high stability absorption properties from waste or natural material to replace concrete Lead (Pb)-based. •Evolution concrete composite as shielding research from 1949 to October 26, 2022.•Data perform using bibliometric analysis and scientific mapping.•To helps scholars, understand evolution of concrete composite as a radiation shield.•Bibliometric perspective help to develop new high absorption of concrete composite.•High stability from waste or natural material to replace concrete Lead (Pb)-based.

    Hiba Omer, H. Salah, N. Tamam, Omer Mahgoub, A. Sulieman, Rufida Ahmed, M. Abuzaid, Ibrahim E. Saad, Kholoud S. Almogren, D.A. Bradley (2023)Assessment of occupational exposure from PET and PET/CT scanning in Saudi Arabia, In: Radiation physics and chemistry (Oxford, England : 1993)204 Elsevier Ltd

    Nuclear medicine diagnostic procedures such as positron emission tomography (PET) scans and hybrid imaging using a combination of PET and computed tomography (CT), commonly referred to as PET-CT scanning. Hybrid imaging, which allows accurate visualization of internal anatomical structure and the consequent physiological processes simultaneously, is extensively used in oncology and other departments. Nevertheless, this exposes patients and medical personnel in such departments to significant doses of ionizing radiation, especially in hybrid imaging, where two sources of radiation (the radiopharmaceutical infusion and the CT scanner) are used. This necessitates strict compliance with international guidelines and regulations on radiation protection. Recent reports showed that occupational staff exposure might exceed the annual dose limits. This study evaluated occupational exposure associated with diagnostic hybrid PET-CT imaging and the consequent risks. Twenty medical personnel: 5 physicists, ten technologists, two medical doctors, and three nurses are included in this study. The assessment includes measuring occupational ambient doses using calibrated optical stimulating-luminescent dosimeters (OSL) (Al2O3:C). These badges were read using an automatic OSL reader. The results, displayed as (mean ± standard deviation): (range) of the effective dose (mSv) for the different personnel, can be summarized as follows(mean standard deviation and range). Physicists 0.72 ± 0.14 (0.49–0.83) mSv in 2019 and 0.67 ± 0.07 (0.59–0.78) in 2020; technologist 1.4 ± 0.96 (0–3.27) mSv in 2019 and 1.395 ± 1.27 (0.64–4.36) mSv; medical doctors 0.445 ± 0.42 (0.15–0.74) mSv in 2019 and 0.70 ± 0.04 (0.67–0.73) in 2020; and nurses 1.38 ± 0.25 (1.21–1.66) mSv in 2019 and 1.41 ± 0.17 (1.23–1.55) in 2020. The tube voltage of the scanner used in this study had a constant value of 120 kVp for all patients. Staff working in PET or PET-CT departments receive significant doses from the radiopharmaceuticals and the energetic gamma rays from the CT scanners. Hence, optimizing the CT acquisition parameter is necessary to optimize the occupational doses and restrict them to acceptable dose limits. •Occupational ambient doses were quantified using calibrated (OSL (Al2O3:C) dosimeters.•Staff working in PET or PET-CT departments receive significant occupational doses.•Nurses received higher doses compared to other personnel.•Staff annual exposure is within the defined dose limits.

    Mohamed Y. Hanfi, Ahmed E. Abdel Gawad, Hassan Eliwa, Khaled Ali, Malaa M. Taki, M. I. Sayyed, Mayeen Uddin Khandaker, David A. Bradley (2022)Assessment of radioactivity in Granitoids at Nikeiba, Southeastern Desert, Egypt; radionuclides concentrations and radiological hazard parameters, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier

    Assessment of the radioactive impacts of building materials has become important before materials are employed in various infrastructure fields. The current study conducted a radiological survey on multiple granitoids in the Nikeiba area, southeastern Desert, Egypt. The petrographically studies were performed and illustrated the presence of radioactive bearing minerals in the investigated granitoids. The activity concentrations of 238U, 232Th, and 40K in these rocks, including the granitoids, are measured using a GS-256 spectrometer with a 0.35 L sodium iodide (NaI) thallium activated detector. The activity concentration of 238U, 232Th, and 40K varied from 1 +/- 0.3, 4 +/- 1 and 94 +/- 15 Bq kg-1 to 274 +/- 74, 229 +/- 24, and 3537 +/- 436 Bq kg-1 with the mean value of 83 +/- 47, 104 +/- 50 and 1140 +/- 462 Bq kg -1, respectively. Multivariate statistical analysis is applied to detect the correlation and similarities of radionuclides with the radioactive hazard indices. Pearson correlation analysis depicts the distribution of 232Th controls the distribution of 238U in the granitoids. The primary radiological health hazard characteristics related to the concentrations of 238U and 232Th were determined by the variance of 89.76% derived using PCA. The cluster analysis dendrogram results indicate a good match with the correlation analysis.

    Entesar Z. Dalah, David A. Bradley (2023)Protocols-based notification versus diagnostic reference levels as an optimization tool in computed tomography, In: Radiation physics and chemistry (Oxford, England : 1993)209 Elsevier Ltd

    We compare a dose baseline optimization tool built around clinical protocols and notification of dose based on the diagnostic reference level (DRL). In regard to computed tomography (CT), retrospective analysis has been made of the volume CT dose-index (CTDIvol) and dose-length-product (DLP) for a total of 230 adult patients undergoing enhanced CT abdomen and pelvis examinations. From this, a dose baseline was established. The DRL based notification level (NL) was set at twice the Local DRL. The protocol baselines for dose were set at the median and 75th percentiles of dose spectrum. Spearman coefficient and one-way ANOVA tests were used for statistical correlation and differences between DLP and various CT protocols. Significant differences (p 

    Abdullah Alsubaie, L. Alsulaiti, Abdullah N. Al-Dabbous, Mariem Chamakh, Maisarah Jaafar, Eman Daar, Abdulaziz H. Alanazi, Yasir Altowairqi, Z. Podolyak, N. I. Ward, D. A. Bradley (2019)A comparison of elemental presence in Riyadh and Doha road dust, In: Radiation physics and chemistry (Oxford, England : 1993)154pp. 58-63 Elsevier

    The monitoring of trace element concentrations in roadside dust can be used to evaluate vehicular contributions to the environment. Here we compare the utility of two analytical techniques for elemental analysis of dust samples, SEM/EDX and ICP-OES, detecting elements from Mg to Au. In an evaluation of roadside dust at several different sites within the campus of King Saud University, situated in Riyadh, and the University of Qatar, situated in Doha, four elements are observed to be particularly prominent: Al, Fe, Mg, and Si, notwithstanding that they all have natural abundance in desert sands. This study implicates the influence of new technology in vehicle construction, including engine capacity (vehicles in these countries tending to be of relatively large engine capacity). The concentrations of Al, Fe and Mg in Doha show greater elevations compared to that obtained in Riyadh, both cities being centres of large urban populations, the levels in both cities also being enhanced above uncontaminated regional sands. Absolute values have been determined from use of the ICP-OES facility while the SEM/EDX technique has provided evaluation in terms of weight %, offering complementary information on the contribution of elemental concentrations from vehicular emissions.

    Z. Zakaria, M.Z. Abdul Aziz, N.H. Ishak, S. Suppiah, D.A. Bradley, N. Mohd Noor (2020)Advanced thermoluminescence dosimetric characterization of fabricated Ge-Doped optical fibres (FGDOFs) for electron beams dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)166 Elsevier Ltd

    For fabricated Ge-doped optical fibres (FGDOFs) investigation is made of a range of optical fibre thermoluminescence (TL) characteristics: sensitivity, dose linearity, dose rate dependence and fading together with exploration also made of percentage depth dose (PDD) curves for electron beams dosimetry. The fibres used were of various shapes, cross-section dimensions and germanium (Ge) concentrations. The responses of FGDOFs were compared against commercial fibres as well as that of an ionization chamber (PTW 31010 Semiflex 31010) and Gafchromic™ EBT3 films. All fibres were irradiated at the Royal Surrey County Hospital (UK) using 6-, 9- and 12 MeV electron energies, with 100 cm focus-to-sample distance (FSD) and 10 × 10 cm2 field size, measurements being made up to the depth of dose maximum, Zmax. At a fixed 9 MeV electron energy, dose rates from 100 up to 600 cGy/min were used with field sizes ranging from 6 × 6 cm2 to 25 × 25 cm2. For PDD curves, the fibres were placed at depths from 0 cm to 6 cm, comparison being made against the ionization chamber and films. The water-to-air stopping power ratios and the fluence correction factors, Pfl were required in determining PDD curves when using the ionization chamber. TL yields against dose were highly linear (R2 > 0.99). A low dependence on dose rate was found for all fibres. The 2.3 mol% flat fibre (FF) produced the superior performance, with the highest sensitivity, minimum TL fading for up to 3 months as well as relative difference of less than 2% for the build-up and fall-off region for PDD curves. •The fabricated Ge-doped fibres characteristics for electron beams were studied.•Exploration also made of percentage depth dose (PDD) curves.•A low dependence on dose rate was found for all fibres.•The 2.3 mol% flat fibre (FF) produced the superior performance with minimal fading.•A small relative difference for PDD curves regions was observed.

    A. Sulieman, E. Yousif, M. Alkhorayef, E. Mattar, E. Babikir, D. Bradley (2018)Lens dose and radiogenic risk from Tc-99m nuclear medicine examinations, In: Journal of radioanalytical and nuclear chemistry318(1)pp. 797-801 Springer Nature

    Evaluation has been made of the radiogenic risks to patients and personnel during Tc-99m diagnostic nuclear medicine examinations. A highly sensitive form of thermoluminescent dosimeter, type TLD-GR200A (LiF: Mg, Cu, P), was used to quantify occupational exposure. Ambient exposure rates and patient doses were also assessed using a survey meter and knowledge of the administered activity respectively. For bone, renal and thyroid scans, the mean Tc-99m administered activities were 925.0 MBq, 148.0 MBq and 166.5 MBq respectively. The staff annual dose was estimated to be 11.2 mSv and eye lens dose equivalent was 2.2 mSv. The dose values are greater in comparison with other studies but with the current workload and practices they remain within the annual occupational dose limit.

    Abdullah Alsubaie, L. Alsulaiti, Eman Daar, Abdullah N. Al-Dabbous, Mariem Chamakh, Maisarah Jaafar, D.A. Bradley (2019)Elemental evaluation of urban road dirt via three analytical techniques, In: Radiation physics and chemistry (Oxford, England : 1993)165 Elsevier Ltd

    Worldwide, toxicological consequences are arising from vehicular contributions to environmental pollution. Herein, elemental monitoring has been conducted of road dirt via three analytical techniques, sampling being made along the busy campus roads of universities/research institutes in Guildford and Riyadh. Using the ICP-OES and ICPMS techniques, absolute values have been determined for Ti, Mn, Mg, Co, Zr, Mo, Ba, Tl, V, Rd, Cu, Zn, Ni, Cr, Cd, and As, while an SEM/EDX technique has provided weight % values. Results, both qualitative and quantitative, are compared. By using SEM most prominent among the elements observed in the road samples are Al, Fe, Mg, and Si, particularly in the Gulf city of Riyadh and are in agreement with values observed in previous work by the same group. By using ICPMS and ICPOES Mg, Ti, V, Cu, Zn, Ni, Cr and Ba have also been observed in both climates, albeit at lower concentrations than that found for Al, Fe, and Mg, with particle sizes of < 45 μm. Elemental presence is seen to be influenced by climatic conditions as well as vehicle engine size. In conclusion, the various techniques offer complementary information on vehicular emission elemental concentrations in urban environments. •Metal element concentrations in road dust samples investigated.•Results from SEM/EDX, ICP-MS and ICP-OES compared.•Elevated levels found, although less so in UK road dirt.•The concentrations of Mg show greater elevations in several Gulf locations.

    Hussin Aamri, Andrew Fielding, Ali Aamry, Abdelmoneim Sulieman, Nissren Tamam, Mohammed Alkhorayef, David A. Bradley (2021)Comparison between PRIMO and EGSnrc Monte Carlo models of the Varian True Beam linear accelerator, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    The study objectives were to simulate a 6 MV flattening filter-free (FFF) photon beam of a TrueBeam Varian LINAC, using the PRIMO code. The depth-dose profiles for various jaw open fields and cross-beam profiles for various depths inside water phantoms were determined using PRIMO simulations and were compared with the EGSnrc simulation results. A 93% match between both codes has generally been obtained, with a systematic variation in agreement between the two models that increases with field size. The closest agreement, to within 94%, was obtained for a 6 × 6 cm2 jaw open field at 5.0 cm and 10.0 cm depths, better at 10- than at 5.0 cm depth. The effects of how scatter is modelled has been shown to result in the differences. •6 MV flattening filter-free photon beam of a TrueBeam Varian LINAC was simulated.•PRIMO code simulations were compared with the EGSnrc simulation results.•A 93% match being between both codes has generally been obtained.•PRIMO can be successfully used as an alternative code for dosimetric calculations.

    Zuraidah Sulaiman, Hanis Syuhada Ahmad Sugiran, Nornajihah Nadia Hasbullah, Adaviah Mas'od, Suhairul Hashim, David Andrew Bradley (2022)Public Awareness of Consumer Products Containing Radioactive Materials: Empirical Evidence from Malaysia, In: International journal of environmental research and public health19(4) Mdpi

    The emergence of online purchase platforms makes products containing radioactive materials more accessible to consumers. These products are gaining popularity and are widely available and easily accessible in the market today. This study examined how consumer's psychological factors affect their decision of purchasing products containing radioactive materials in the market. Based on the protective action decision model (PADM) and the heuristic-systematic model (HSM), this study proposed a model to add to the literature on consumer awareness of risky products. In particular, this study investigated which type of regulatory focus message (promotion-focused advertisement or prevention-focused advertisement) is significant in moderating the effects of radiation safety knowledge and product knowledge on risk perception when purchasing products containing radioactive materials. The relationship between consumers' risk perception and information seeking, which leads to the purchase intention of such products was also investigated. Advertisements with varying regulatory focus messages were randomly distributed to participants to determine whether consumers are more influenced by promotion-focused advertisement or prevention-focused advertisement to mitigate the risk of purchasing products containing radioactive materials. The results revealed that promotion-focused advertising messages evoked a positive effect on consumers' radiation safety knowledge and product knowledge toward risk perception. However, prevention-focused regulatory advertising messages did not moderate the relationships between both radiation safety knowledge and product knowledge on consumers' risk perception. This study offers guidelines for manufacturers, sellers, and marketers of products containing radioactive materials, and, importantly, for the government to devise strategies in designing effective social marketing advertisement for business, environmental and societal benefits.

    Muhammad Safwan Ahmad Fadzil, Noramaliza Mohd Noor, Ung Ngie Min, Norhayati Abdullah, Mohd Taufik Dolah, Mahzom Pawanchek, David Andrew Bradley (2022)Dosimetry audit for megavoltage photon beams applied in non-reference conditions, In: Physica medica100pp. 99-104 Elsevier

    Purpose: We have conducted for the first time a Malaysian postal dosimetry audit of external beam under non -reference conditions by evaluating the output performance while screening for systematic errors within the dosimetry chain. The potential use from the choice of detector were investigated along with the search for other sources of discrepancies. Methods: Ten radiotherapy centres were audited, encompassing 16 megavoltage photon beam arrangements, adopting the IAEA postal dosimetry protocol for non-reference conditions, with a holder modified to accommodate three TLD types: Ge-doped cylindrical silica fibres (CF), Ge-doped flat silica fibres (FF), and TLD-100 powder. Results: Eight of the centres operated within +/- 5% of stated dose, one other exceeding tolerance for all measured points, and one did not return any dosimeters for analysis after failing the initial irradiations. Post remedial measures, the mean relative response for CF, FF, and TLD-100 was 1.00, 0.99, and 0.98 respectively, with associated coefficients of variation 6.87%, 6.45%, and 5.06%. Conclusion: High quality radiotherapy clinical practice postal dosimetry audits that are based on sensitive TLDs are seen to be particularly effective in identifying and resolving dose delivery discrepancies.

    Habila Nuhu, Suhairul Hashim, Mohamad Syazwan Mohd Sanusi, Sib Krishna Ghoshal, David A. Bradley (2022)Thoron activity concentration in Malaysian soil gas: Geogenic impact assessment, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier

    Given the rather short half-life of thoron (220Rn), at 56 s, its contribution to radiation exposure is often over-looked. Nevertheless, in a thorium (232Th) rich environment potential hazard does exist, in particular regarding prolonged duration exposures to 220Rn and its short-lived alpha-particle emitting progeny [polonium (216Po)]. Herein, concerning the geology and major soil types in the Malaysian state of Perak, an activity concentration map has been established for 220Rn in soil gas, with the use made of a RAD7 detector and the THORON protocol for in-situ measurements. The detector has been coupled to a soil probe driven to a depth of 0.8 m. The activity concentration of 220Rn in the soil ranged from undetectable to 563 kBq m- 3 with a mean value of 38 +/- 11 kBq m- 3. Granite and Triassic-Jurassic formations in the region showed more elevated 220Rn activity while Qua-ternary and Silurian formations revealed low 220Rn values. Moreover, while elevated 220Rn activity concentra-tions were found in peat, riverine, and granite source soils, the activity concentrations in marine and other soils were low. A primary map of 220Rn in the soil gas has been developed based on geogenic impact assessment, with a greater 220Rn activity concentration in the central part of the state.

    K. Ley, S. A. Hashim, A. Lohstroh, C. Shenton-Taylor, D. A. Bradley (2020)Thermoluminescent response of silica beads to high-dose irradiations, In: Radiation physics and chemistry (Oxford, England : 1993)167 Elsevier

    Glow-curves obtained using a Riso TL/OSL reader, have been studied for 10 different coloured bead types from the manufacturer Toho, Japan, after irradiation using a 1 MeV electron beam at the Alurtron Irradiation Facility, Malaysia Nuclear Agency, giving doses up to 250 kGy. For doses larger than and including 5 kGy, it can be observed by eye that the beads darken with increasing dose. The beads almost return to their original appearance after being read out and annealed at 400 degrees C, showing the potential for a colour changing dosimeter that is reusable and chemically inert. Beads showing the highest TL response are the Frosted and Pink colours which show evidence of a possible maximum Mass Normalised TL Response as a function of dose in the range of 40 kGy-50 kGy. Data fitting was achieved using weighted fits of second order exponentials and linear fits for different data sets, with calculated p-values

    S E Lam, N Mohd Noor, D A Bradley, R Mahmud, M Pawanchek, H A Abdul Rashid (2020)Small-field output ratio determination using 6 mol% Ge-doped silica fibre dosimeters, In: Biomedical physics & engineering express6(6) IOP Publishing

    This work investigates the suitability of locally fabricated 6 mol% Ge-doped optical fibres as dosimeters for small-field output ratio measurements. Two fabrications of fibre, cylindrical (CF) and flat (FF) fibres, were used to measure doses in small photon fields, from 4 to 15 mm. The findings were compared to those of commercial Ge-doped fibre (COMM), EBT3 film and an IBA CC01 ionization chamber. Irradiations were carried out using a 6 MV SRS photon beam operating at a dose rate of 1000 cGy min−1, delivering a dose of 16 Gy. To minimise the possibility of the fibres failing to be exposed to the intended dose in small fields, the fibres were accommodated in a custom-made Perspex phantom. For the 4 mm cone the CF and FF measured output ratios were found to be smaller than obtained with EBT3 film by 32% and 13% respectively. Conversely, while for the 6 to 15 mm cone fields the FF output ratios were consistently greater than those obtained using EBT3 film, the CF output ratios differed from those of EBT3 film by at most 3.2%, at 6 mm, otherwise essentially agreeing with EBT3 values at the other field sizes. For the 4 to 7.5 mm cones, all output ratios obtained from Ge-doped optical fibre measurements were greater than those of IBA CC01 ionization chamber. The measured FF and CF output ratios for the 7.5 to 15 mm cones agreed with published MC estimates to within 15% and 13%, respectively. Down to 6 mm cone field, present measurements point to the potential of CF as a small-field dosimeter, its use recommended to be complemented by the use of EBT3 film for small-field dosimetry.

    Nwokoma Oliver Chijioke, Mayeen Uddin Khandaker, Kolo Matthew Tikpangi, D.A. Bradley (2020)Metal uptake in chicken giblets and human health implications, In: Journal of food composition and analysis85 Elsevier Inc

    •14 heavy metals were determined in 280 poultry chicken giblets.•Presence of Sr and Sb in chicken giblet determined for the first time•Essential metals show higher values than the potentially toxic metals.•Estimated carcinogenic risk show higher values than the US-EPA safety limit.•Chemical risk due to some essential metals show no harm for giblets to be consumed. Recognizing the global concerns about metal contamination in food chain coupled with the high rate of consumption of chicken products as a major component of daily diet to humans, the presence of 14 metals (Fe, Cu, Mg, Zn, Al, Hg, Cd, As, Pb, Se, Ni, Sr, Cr and Sb) due to their persistence in our environment and food chain were determined in poultry chicken giblets to assess the potential non-carcinogenic and carcinogenic risks to human health. In general, essential elements such as Mg, Fe show higher concentrations than the potentially toxic metals. Statistical analysis indicates the latter to have similar origin and/or similar feedstuffs, consistent with the wide spread use of Cu and Zn as feed supplements in intensive poultry farming. The daily intake of the studied metals by the Malaysian population showed to be below the permissible levels of dietary intake set by various international organizations. Estimated non-carcinogenic risk due to all of the metals in the giblets show a value of 0.51 indicating the giblets to be safe for consumption at the current intake level. However, the carcinogenic risk resulting from toxic metals show slightly higher values than the US-EPA reference limit of 10−4. The results may not be thought to be of concern given the fact that chicken giblets form only a very minor part of dietary habit. However, considering the non-degradability of toxic metals and their potential accumulation in animal tissues, reduction in metal supplementation in animal feed should be introduced and periodic monitoring of chicken giblets may help to mitigate non-essential metal toxicity to public health.

    Amjad Alyahyawi, Alexis Dimitriadis, Andrew Nisbet, D.A. Bradley (2021)GeB flat fibre TL dosimeters for in-vivo measurements in radiosurgery, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    Noting an increase in demand for procedures involving clinical radiosurgery we seek to develop a high spatial resolution thermoluminescence dosimeter (TLD) to allow conduct of in vivo dose verification measurements. An associated need is for a dynamic dose range exceeding that of the well-established LiF (Mg,Ti) phosphor TLD-100, with in particular the latter being limited in performance at the elevated doses seen in radiotherapy. The work investigates the performance of a novel GeB co-doped Flat Fibre (GeB-FF) fabricated using the modified chemical vapour deposition (MCVD) process, the hollow capillary optical fibres (COF) produced from this being collapsed down into flat fibres (FF) to create strain-related defects. This process has already been demonstrated to increase the low dose sensitivity of optical fibres, notably at diagnostic x-ray potentials, with Minimum Detectable Dose (MDD) values of down to 0.1 μGy. The intent of present work, conducted as a component of a safety audit, part of the hospital periodic radiation protection quality assurance program, has been to examine and compare the performance of the two forms of TL dosimeter, GeB-FF and TLD-100, measuring scattered radiation resulting from cranial cavity radiosurgery procedures. The dosimeters were placed on the neck, chest and pelvis of 20 patients. Using both types of dosimeter, raw dose values at each site show general accord (±3 mGy at 1 σ), covering mean doses ranging from some 10 mGy to less than 1 mGy, representing doses of

    H. Salah, Mohammad Rabbaa, Mohammad Abuljoud, A. Sulieman, M. Alkhorayef, Nissren Tamam, D. A. Bradley (2021)Evaluation of patients radiation dose in computed tomography paranasal sinuses in children, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier

    This study evaluates pediatric patients' radiation doses during paranasal CT procedures. A total of 48 (28 (58.3%) male, 20 (41.7%) female pediatric patients have undergone CT paranasal sinuses (PNS) in three consecutive years. The pediatric patient's radiation exposure was estimated based on justified medical procedures. Calibrated multidetector CT (MDCT) machine (Siemens Somatom Sensation 64 (64 detectors)) was used for all the procedures. All the PNS procedures were conducted at Riyadh Care Hospital. The parameters included the volume CT dose index (CTDIvol (mGy) and dose length product (DLP) ( The mean, standard deviation and range of the volume CTDI (mGy) and DLP ( for the 3 particular years were (2018) 9.36 (3.49-34.88), 196.1 (56.27-812.1), (2019) 16.9 (3.74-45.8), 333.9 (55.8-832.9) and (2020) 22.8 (4.03-45.8), 474.9 (63.9-979.02), respectively. Patients' doses were lower compared to most previous studies. However, proper exposure parameters and precise justification will reduce pediatric radiation doses during CT-PNS significantly.

    A. K. M. Mizanur Rahman, Mahfuza Begum, H. T. Zubair, H. A. Abdul-Rashid, Z. Yusoff, N. M. Ung, D. A. Bradley (2020)OSL using a prototype fibre-mounted sensor and automated reader assembly, In: Radiation physics and chemistry (Oxford, England : 1993)166 Elsevier

    Application-viable yields of optically stimulated luminescence (OSL) are known to be provided by a number of materials, Al2O3:C nanoDot OSLDs being one of those currently favoured, dominating the world of commercial passive radiation dosimetry. Associated with the use of such materials is the need for versatile, high performance readout devices, opportunities remaining for novel developments in support of the OSL media, as emphasised herein. Present study focuses on the data acquisition capability of an in-house prototype OSL reader, luminescence stimulation being provided by a 30 mW green LED light (spectral mid-point similar to 515 nm). In providing for the additional versatility of making stand-off (at a distance) measurements, the dosimeter sensors (nanoDot OSLD chips) were attached to a polymethyl-methcrylate (PMMA) fibre cable, allowing characterization of the OSL (phosphorescence) at very low risk. Using this prototype instrument, key OSL features from an Al2O3:C sensor medium have been captured, excellent quantitative agreement being found between present results and those of others using other readers. One further feature of the current design is that it also allows investigation of the excitation light wavelength dependence of sensor media that could be competitive to Al2O3:C, there being the additional ability to swap out the OSL sensor, filters and other support components.

    S. E. Lam, D. A. Bradley, M. U. Khandaker (2021)Small-field radiotherapy photon beam output evaluation: Detectors reviewed, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier

    Small fields (few cm and below) are being applied in therapy independently or as mm/sub-cm segments of larger fields. Included are intensity modulated radiotherapy (IMRT)/volumetric modulated arc therapy (VMAT), proton beam therapy, stereotactic radiosurgery (SRS)/stereotactic radiotherapy (SRT) and stereotactic body radiotherapy (SBRT). With an ability to more closely conform to the target volume, small field applications are nevertheless a challenge to accurate dose evaluation and treatment planning. The influencing factors include finite source size, steep dose gradients, charged particle disequilibrium, detector size and associated volume averaging effects, and changes in energy spectrum and associated dosimetric parameters. Accordingly, small field dosimetric problems attract interest, not least in consideration of new generation small-volume detectors that promise to reduce energy and dose/dose-rate dependence, also perturbation effects. These include developments made prior to the IAEA-AAPM TRS-483 report on the dosimetry of small static fields in external beam radiotherapy. In present review, the small-field problem is revisited, attention being given to output factor determination using contemporary detectors (Gafchromic film, microDiamond-, diodeand plastic scintillation detectors), also optical fibre dosimeters developed by a University of Surrey/Malaysian Consortium, measurements being made in flattening (FF) and flattening filter-free (FFF) beams. Also included are the effects on output factors in using the daisy-chaining approach associated with the small-field detectors. A survey of small-size dosimeter research shows insignificant difference in small-field output values obtained via direct normalisation or daisy-chaining approach. For fields down to 1 x 1 cm(2), microDiamond detector, stereotactic field diode (SFD) and EBT3 film show minor differences (< 3.4%) in the dose response ratio between flattened and non-flattened beams. Present review emphasizes the use of at least two dosimeters to address the variations in small-field dose response using the active micro-dosimeters or passive dosimeters discussed herein.

    Halmat J. Hassan, S. Hashim, N. Z. H. Abu Hanifah, M. S. M. Sanusi, M. R. Fahmi, R. M. Tahar, D. A. Bradley (2022)Use of tourmaline-based healthcare products and associated radiation risks, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier

    Investigation is made of 23 commercially available tourmaline-based healthcare products containing naturally occurring radioactive material (the products including hot spa stones, face masks, waist supporter slimming belts, arm relief belts, socks, insoles, soaps, and combs) with negative ion health benefits claimed by the purveyors. Assessment is made of the radiological risk posed by the use of such products, external exposure dose being the particular focus. Gamma spectroscopy analysis and Geant4 Monte Carlo (GMC) simulations are used. Organ doses are obtained using male and female human phantoms, dose conversion factors (DCFs) being included. For U-238 and Th-232t the tourmaline sock, code T20 was found to contain the greatest activity, at 2.4 +/- 0.2 and 28.0 +/- 1.3 Bq g(-1) respectively; least was for the magnetic therapy face mask, code T02, at respective values 0.04 +/- 0.01 and 0.1 +/- 0.01 Bq g(-1). Across all of the tourmaline products, the K-4 range was 0.16 +/- 0.01-16.4 +/- 1.1 Bq g(-1). In terms of elemental concentration, sample T20 offered the greatest concentration, with mean percentages of 0.022 +/- 0.001 and 0.78 +/- 0.10, for Th and U, respectively. With the assumption of exposure for a period of 8 h per day, wearing the tourmaline sock product T20 would give rise to an annual effective dose of 0.64 mSv, less than the public annual dose limit of 1 mSv. Noting that the samples may give rise to greater doses, national screening programmes for activity are suggested in seeking to mitigate unnecessary radiation exposure.

    A. Sulieman, H. Adam, N. Tamam, M. Alkhorayef, A. Alhailiy, S. Alghamdi, A. Elnour, O. Alomair, Y. Alashban, M. U. Khandaker, D. A. Bradley (2021)A survey of the pediatric radiation doses during multiphase abdominal computed tomography examinations, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier

    This work investigates pediatric patients' radiation doses during multiphasic computed tomography (CT) abdomen procedures in six hospitals. A total of 58 (14 (24% females)) and 44 males (44, 76%) underwent CT single or multiphase procedures. A single phase and triple phase CT examination were carried a wide range of clinical indications, including renal and digestive systems pathologies. All procedures were performed at six radiology departments. Three departments are equipped with 16 slice CT machines, and the other three departments are equipped with 160, 128 and 16 slice CT machines. The overall 3rd quartile values for CTDIvol (mGy) and DLP ( were 8.6 +/- 4.7 (mGy) and 1580 +/- 594.64 ( per CT abdomen procedure. The current study indicates the need for dose optimization for pediatric patients by establishing proper imaging protocols based on the international guidelines. The variation in patients' doses is attributed to variation in the imaging protocols, scan length and number of phases performed per pediatric CT abdomen procedure.

    Adebiyi Oresegun, H.T. Zubair, Louay Ghassan, Hairul Azhar Abdul-Rashid, Siti Aiasah Hashim, David A. Bradley (2021)Effects of hydroxyl content in pure silica optical fiber exposed to kGy electron beams, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    We present a study on the effect of high dose (kGy) electron beams on pure silica core fibers through examining the following phenomena within the fibers: radioluminescence (RL), radiation induced attenuation (RIA), and recovery. The objective is to identify the relevant characteristics of these fibers having favourable radiation response, that can be utilized in the development of dose measurement systems for high dose (kGy) environments. Two types of 20 m long pure silica optical fiber samples have been used, differing in their concentrations of hydroxyl (OH) content. Segments of 3.5 m length from each fiber were wound into coils of radius ~25 cm and exposed to consecutive irradiation doses, in the order of tens of kGy (10 kGy through 70 kGy in individual exposures), leading to a cumulative dose of some 300 kGy. The low-OH fiber showed saturation of response at the shorter wavelengths of the RL spectrum for doses of 30 kGy and above, resulting from presence of Oxygen Defect Centers (ODC). At the longer wavelengths the RL response of the low-OH optical fibers is observed to increase with dose, attributed to various bonding structural defects of silica nanoclusters. The saturation effect at shorter wavelengths is less prominent in the high-OH samples, where a monotonic increase is observed up to ~60 kGy indicating the formation of radiation induced ODC beyond this point. For cumulative dose of ~70 kGy, the highest RIA losses were registered at 550 nm (12.74 dB/m) for low-OH sample, and at 460 nm (4.75 dB/m) for high-OH sample. The high-OH sample showed much faster recovery post-irradiation, making it more suitable for repeated usage. Both the RL and RIA phenomena observed herein show the feasibility of pure silica optical fibers for dose measurement in high dose (kGy) environments up to individual dose of ~70 kGy. •Electron beam induces luminescence of different peak in vary hydroxyl fiber.•Intensity of the emissions peak vary in accordance to the dose.•Radiative induced effects of the optical fiber may occur simultaneously.•Recovery in the silica fiber varies at different emission peak wavelength.

    Halmat Jalal Hassan, Suhairul Hashim, Mohamad Syazwan Mohd Sanusi, David Andrew Bradley, Abdullah Alsubaie, Rafael Garcia Tenorio, Noor Fitriah Bakri, Rozman Mohd Tahar (2021)The Radioactivity of Thorium Incandescent Gas Lantern Mantles, In: Applied sciences11(3)pp. 1-11 Mdpi

    The use of thorium in providing the intense white luminescence emitted from gas mantles, has a history of some 130 years, the initial application pre-dating by several decades large-scale urban electric lighting. Accordingly, the thoriated gas mantle has proved itself to be of enormous utility, remaining popular in more rural areas well into the 20th century, continuing to enjoy use in campsites and street night markets lanterns until today. The discovery of thorium in 1828 preceded the discovery of radioactivity, with subsequent little appreciation initially of any potential harm from exposure to radioactivity. Study has been made herein of small quantities of five different types of the thoriated gas mantle, all purchased online devoid of any control measures. Several approaches were used concerning the Th-232 activity and dose consequence. First, the activity of Th-232 was estimated using an HPGe detector, with sample M5 providing the greatest activity at 1.25 x 10(4) Bq, exceeding the exemption limit for thorium in a mantle. Compared to sample M5, samples M1 to M4 were low in radioactivity, from 5.1 +/- 1.31 to 16.33 +/- 1.92 Bq. Moreover, the thorium content in M5 constituted 50% of the mantle mass, somewhat greater than previous literature values. The dose equivalent rate on the surface of a single M5 mantle was found to be 0.68 mu Sv/h, while at the surface of a pack of six the level was 1.9 mu Sv/h. Monte Carlo simulation codes have been used to obtain organ equivalent and effective dose rates, the greatest close contact (10 cm) exposure to an unlit mantle being to the thymus, at 0.68 mu Sv/h and 0.62 mu Sv/h for a male and female phantom respectively. Accordingly, with packages of thoriated gas mantles potentially giving rise to non-negligible equivalent doses, greater incorporation of controls on the sale of such items in national radiation protection legislation would seem worthy of consideration.

    Abdullah Alsubaie, Maisarah Jaafar, Abdullah N. Al-Dabbous, S. Alomairy, Yasir Altowairqi, Eman Daar, Mohammed Alkhorayef, L. Alsulaiti, K. S. Almugren, N. I. Ward, D. A. Bradley (2019)A comparison of elemental presence in UK and Kuwait road dust, In: Radiation physics and chemistry (Oxford, England : 1993)155pp. 341-347 Elsevier

    The monitoring of concentrations of metals in road dust can be used in evaluating vehicular contributions to the environment. Here we compare the efficacy of several analytical techniques for such samples: XRF, SEM/EDX and ICP-MS, providing for both qualitative and absolute quantitative analysis. To-date we have made evaluation of key elemental levels from roadside dust sampled at different locations within the University of Surrey and the Kuwait Research Institute, in so-doing also investigating the influence of engine size (Kuwaiti vehicles tending to be of larger engine capacity than those in the UK) and the influence of climate, maritime and arid in the present case. With a total of 36 street dust samples collected to-date, 18 have now been analyzed, elemental concentrations being reported for Mg, Al, Ti, Mn, Fe, Co, Zr, Mo, Ba, Tl, V, Rd, Pb, Cu, Zn, Ni, Cr, Cd, As, Hg and Au. For University of Surrey samples, obtained at three different times of the year, SEM/EDX findings range from below the lower limit of detection for Ag, through to 4.7 x 10(-6) mg/m(2) for Co, up to 3.6 x 10(-2) mg/m(2) for Fe. Using ICP-MS on sieved University of Surrey road dust samples similarly taken at different times of the year, mean particle dimensions < 45 mu m (i.e. respirable dust) have been obtained yielding elevated elemental concentrations in units of mg/kg (ppm), with mean values as follows: Cu (70.4 mg/kg), Zn (288 mg/kg,) Al (3081 mg/kg) and Fe (14,133 mg/kg). These values can be compared against that for Co (3.5 mg/kg) and V (12.3 mg/kg), a primary source of the latter deriving from their use in vehicle tyres production, also for 78.0 mg/kg (Pb). Other toxic metals found in the Guildford and Kuwait samples in different low concentrations were Ti, Cr, and Ba. The concentrations of Pb were found to be low compared to previous analyses, attributable to modern restrictions on Pb in fuel. Au and Ag were also detected, albeit in very low concentrations in the samples from both countries, in particle sizes of the order of 0.5 mu m. In summary, present study shows a number of elements presenting at particularly elevated concentrations, a major source being motorpart wear debris.

    S.F. Abdul Sani, M.H.U. Othman, Amal Alqahtani, A.A.Z. Ahmad Nazeri, K.S. Almugren, N.M. Ung, S.A. Hashim, F.H. Alkallas, D.A. Bradley (2021)Passive dosimetry of electron irradiated borosilicate glass slides, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    Thermoluminescence dosimetry most typically concerns the sensing and quantification of ionizing radiation exposures, with evaluation of absorbed dose arising from electron-hole trapping in well-disposed insulating/semi-conducting media. In this passive form of dosimetry the signal derives from photons released post-irradiation heating of the dosimeter over a specific temperature range. Herein, for entrance doses from 2 Gy up to 250 kGy, investigation is made of the thermoluminescence properties of electron irradiated borosilicate glass (SiO2–B2O3), the samples deriving from commercial microscope slides (coverslips) of thickness 1.0 mm. The coverslips provide linear TL response over a wide range of radiation dose, through use of a clinical linear accelerator in a lower dose regime (2–10 Gy) and use of a product-irradiation electron linac in a higher dose regime (25 kGy–250 kGy), obtaining a regression coefficient in excess of 96%. In the high dose regime comparison has been made with the response of Ge–B doped Flat Fibre (FF) and Ge–B doped photonic crystal fibre (PCF) (collapsed). Deconvolution shows the glow curves of the borosilicate glass to be formed of five overlapping peaks, with figures of merit (FOM) of between 0.62 – 1.72 and 0.87–1.00 for the particular dose ranges 2–10 Gy and 25 kGy–250 kGy respectively. Through use of Glowfit deconvolution software, the key trapping parameters of activation energy and frequency factor were calculated for the borosilicate glass slide. •Borosilicate glass slide of 1 mm thickness irradiated to electrons.•The glow curve deconvolution appears five overlapping peaks.•Si–Si and Si–O oxygen interactions are responsible of the overlapping peaks.

    Bindhu Christopher, Y. Sheena Mary, Mayeen Uddin Khandaker, D.A. Bradley, M.T. Chew, P.J. Jojo (2020)Effects of mobile phone radiation on certain hematological parameters, In: Radiation physics and chemistry (Oxford, England : 1993)166 Elsevier Ltd

    Elevated chronic exposure to any sort of radiation is hazardous to human health. Besides ionizing radiation, exposures to electromagnetic radiation mainly from the use of mobile phones have become a matter of great health concern, especially its extended duration use even by children. At the same time there are several unknowns related to the ill effects including carcinogenicity of prolonged exposure. The objective of this investigation was to find the effect on certain vital hematological parameters namely hemoglobin level, white blood cell (WBC) count, platelet count and erythrocytes sedimentation rate (ESR) due to the prolonged exposure to mobile radiations through in vitro examination of human blood samples. Matched case control methodology was adopted for the study. Blood samples were collected by clinicians from 27 voluntary subjects for investigation. From each, one sample was kept un-exposed while the other three samples were exposed to mobile microwave radiations for 60 min continuously in identical and controlled conditions. A 4G hand phone of a very popular brand having transmission frequency range from 2.3 to 2.4 GHz including uplink and downlink was used. Hematological analyses were carried out on fresh samples immediately after collection. For comparison of the levels of hematological parameters, blood exposed to 1 h of phone radiation and control were analysed. Experimental results show that there is a significant change on the hematological components. The exposed blood samples were found to display decrease in platelet count only. Hemoglobin level, ESR rate and the WBC counts were found to be increased. While these observations are performed under controlled laboratory conditions, given the tremendous growth in number of mobile phone users, the effects could be a real concern especially in work places and cities even through passive exposure. •Mobile phone radiation affects blood hemoglobin level, WBC and platelets count and ESR.•Effects of mobile phone radiation on hematological factors studied.•A matched case control approach was adopted for the investigation.•Long time and over exposure to mobile phone radiation may affect the individual health.

    Sneha Sarwar, Md. Jamal Hossain, Nafis Md Irfan, Tamima Ahsan, Md. Saidul Arefin, Arebia Rahman, Abdullah Alsubaie, Badr Alharthi, Mayeen Uddin Khandaker, David A. Bradley, Talha Bin Emran, Sheikh Nazrul Islam (2022)Renoprotection of Selected Antioxidant-Rich Foods (Water Spinach and Red Grape) and Probiotics in Gentamicin-Induced Nephrotoxicity and Oxidative Stress in Rats, In: Life (Basel, Switzerland)12(1) Mdpi

    Objectives: The current study investigated the curative effects of two selected antioxidant-rich foods (water spinach and red grape) and probiotics on the kidney exposed to nephrotoxicity induced by gentamicin. Methods: A total of 30 Wistar Albino female rats equally divided into six groups were studied for seven days. Except for the normal control (NC) group, all groups received 80 mg/kg/day gentamicin (GEN) injection intra-peritoneally for seven days. NC and GEN groups received only regular diet. In the water spinach group (GEN + WS) and red grape (GEN + RG) groups, rats were provided with 20 g/rat/day of boiled water spinach and 5 mL/rat/day of red grape juice, respectively. The probiotic (GEN + P-4) and (GEN + P-8) groups received 4 x 10(9) and 8 x 10(9) viable bacteria, respectively. On the 8th day, all the rats were sacrificed to collect blood and kidney. Serum creatinine, urea, uric acid, malondialdehyde (MDA), nitric oxide (NO), and superoxide dismutase (SOD) were analyzed. In addition, kidney histopathology was taken for final observation. Results: Both antioxidant-rich foods and probiotic (P-4) significantly (p < 0.05) attenuated the GEN-induced oxidative and nitrosative stress and improved kidney function by lowering uremic toxin (serum creatinine, and uric acid) levels. Histopathological findings of kidney tissues of all groups were consistent with the biochemical findings. Conclusion: The current preclinical study suggests that the consumption of antioxidant-rich foods might be a promising fighting option against gentamycin-induced nephrotoxicity and oxidative stress. However, extensive studies and clinical monitoring are immediately required to determine the appropriate probiotic doses and mechanism of action for such effects.

    F. Moradi, Mayeen Uddin Khandaker, T. Alrefae, H. Ramazanian, D. A. Bradley (2019)Monte Carlo simulations and analysis of transmitted gamma ray spectra through various tissue phantoms, In: Applied radiation and isotopes146pp. 120-126 Elsevier

    Studies of radiation interactions with tissue equivalent material find importance in efforts that seek to avoid unjustifiable dose to patients, also in ensuring quality control of for instance nuclear medicine imaging equipment Use of the Monte Carlo (MC) simulation tool in such characterization processes allows for the avoidance of costly experiments involving transmitted X- and gamma-ray spectrometry. Present work investigates MC simulations of gamma-ray transmission through tissue equivalent solid phantoms. Use has been made of a range of radionuclide gamma ray sources, Tc-99m, I-131, Cs-137, Co-60 (offering photons in the energy range from a few keV up to low MeV), popularly applied in medicine and in some cases for gauging in industry, obtaining the transmission spectra following their interaction with various phantom materials and thicknesses. In validation of the model, the simulated values of mass attenuation coefficients (mu/rho) for different phantom materials and thicknesses were found to be in good agreement with reference values (NIST, 2004) to within 1.1% for all material compositions. For all of the primary photon energies and medium thicknesses of interest herein, results show that multiple scattering peaks are generally located at energies lower than 100 keV, although for the larger phantom thicknesses it is more difficult to distinguish single, double and multiple scattering in the gamma spectra. Transmitted photon spectra investigated for water, soft tissue, breast, brain and lung tissue slab phantoms are demonstrated to be practically independent of the phantom material, while a significant difference is observed for the spectra transmitted through bone that was proved to be due to the density effect and not material composition.

    Norfadira Binti Wahib, Mayeen Uddin Khandaker, Nur Aqilah Binti Mohamad Ramli, S. F. Abdul Sani, D. A. Bradley (2019)Commercial kitchenware glass as a potential thermoluminescent media for retrospective dosimetry, In: Applied radiation and isotopes148pp. 218-224 Elsevier

    Study has been made of the thermoluminescence (TL) yield of various glass-based commercial kitchenware (Reko-China, Skoja-France, Godis-China, Glass Tum-Malaysia, Lodrat-France). Interest focuses on their potential for retrospective dosimetry. Use was made of a(60)Co gamma-ray irradiator, delivering doses in the range 2-10 Gy. Results for the various media show all the glassware brands to yield linearity of response against dose, with a lower limit of detection of similar to 0.06 and similar to 0.08 Gy for loose and compact powdered samples. Among all of the brands under study, the Lodrat glassware provides the greatest sensitivity, at 6.0 E + 02 nC g(-1) Gy(-1) and 1.5E +03 nC g(-1) Gy(-1) for compact- and loose-powdered forms respectively. This is sufficiently sensitive to allow its use as a TL material for accident dosimetry (2 Gy being the threshold dose for the onset of a number of deterministic biological effects, including skin erythema and sterility). Energy Dispersive X-ray (EDX) analyses have been conducted, showing the presence of a number of impurities (including C, O, Na, Mg, Al, Si, Ca and Br). Fading of the irradiated glasses show the amount of better than 3% and 5% of the stored energy for both loose and compact powdered samples within 9 days post irradiation. As such, commercial kitchenware glass has the potential to act as relatively good TL material for gamma radiation dosimetry at accident levels. This is the first endeavour reporting the TL properties of low cost commercial kitchenware glasses for gamma-ray doses in the few Gy range, literature existing for doses from 8 Gy to 200 Gy.

    Adebiyi Oresegun, Zubair H Tarif, Louay Ghassan, Hafiz Zin, Hairul Azhar Abdul-Rashid, D A Bradley (2021)Radioluminescence of cylindrical and flat Ge-doped silica optical fibers for real-time dosimetry applications, In: Applied radiation and isotopes176pp. 109812-109812

    Investigation has been made of the radioluminescence dose response of Ge-doped silica flat and cylindrical fibers subjected to 6 and 10 MV photon beams. The fibers have been custom fabricated, obtaining Ge dopant concentrations of 6 and 10 mol%, subsequently cut into 20 mm lengths. Each sample has been exposed under a set of similar conditions, with use made of a fixed field size and source to surface distance (SSD). Investigation of dosimetric performance has involved radioluminescence linearity, dose-rate dependence, energy dependence, and reproducibility. Mass for mass, the 6 mol% Ge-doped samples provided the greater radioluminescence yield, with both flat and cylindrical fibers responding linearly to the absorbed dose. Further found has been that the cylindrical fibers provided a yield some 38% greater than that of the flat fibers. At 6 MV, the cylindrical fibers were also found to exhibit repeatability variation of

    Sabina Yasmin, Z. Siti Rozaila, Mayeen Uddin Khandaker, Bijoy Sonker Barua, Faruque-Uz-Zaman Chowdhury, Md. Abdur Rashid, David A. Bradley (2018)The radiation shielding offered by the commercial glass installed in Bangladeshi dwellings, In: Radiation effects and defects in solids173(7-8)pp. 657-672 Taylor & Francis

    One sign of a vibrant Bangladeshi economy has been the move away from the use of more traditional housing materials towards a preference for modern constructional media. Glass, one such example, used both decoratively and in a structural context, offers various advantageous properties and facets including a protective feature against radiation that has not previously been considered. Current interest examines the dosimetric possibilities offered by the commercial glass as a secondary shield and also in retrospective ionising radiation exposure analysis. Four popular brands of window glass are investigated, all available within the local market (PHP-Bangladesh, Usmania-Bangladesh, Nasir-Bangladesh and Rider-China), all with the same thickness and colour, varying in terms of elemental weight fractions as evaluated by energy dispersive X-ray analysis. As potential attenuators of transmitted radiation thereby forming secondary barriers against radiation exposure from penetrating radiations, the four brands of glass have been studied using photon energies from 59 up to 1332 keV, a range of values representative of that potentially encountered in incidents. Use has been made of a well-shielded high-purity germanium -ray spectrometer and associated electronics, providing for evaluation of the characteristic barrier parameters of half-value layer, radiation protection efficiency and effective atomic number (Z(eff)). Of the four brands investigated, Rider provides superior secondary shielding performance. Concerning potential retrospective dosimetry the effective atomic number of the glass samples are comparable with that of the commercial thermoluminescence (TL) dosimeter TLD-200. At high doses, the TL yields are sufficient to provide for retrospective accident dosimetry.

    Siti Nurasiah Mat Nawi, Mayeen Uddin Khandaker, S. F. Abdul Sani, S. E. Lam, N. M. Ung, K. S. Almugren, D. A. Bradley (2022)Low-cost commercial graphite-rich pencils subjected to electron irradiation for passive radiation dosimetry, In: Applied radiation and isotopes188pp. 110419-110419 Elsevier

    Various thicknesses of 2B grade polymer pencil lead graphite (PPLG) were used in the present study, which focussed on the alteration in crystalline lattice and the structural defect caused by the electron irradiation dosage ranging from 0.5 to 20 Gy delivered by an Elekta HD Linac. The fundamental trap parameters i.e. kinetics order (b), activation energy (E), and frequency factor (s) of the PPLG samples have been estimated using the initial rise and peak shape approaches by fitting the thermoluminescence (TL) glow peaks of the PPLG samples exposed to 20 Gy. The lifetime of the TL glow peak is also presented, which provides information on the stability of the TL signal at maximum temperatures. Raman, Photoluminescence (PL), and X-ray diffraction (XRD) spectra are being used to observe the structural changes that have occurred as a result of the radiation doses. These spectroscopies offer an understanding of the physical parameters that are related to the defects and taking part in the lumi-nescence process. When all of the data are taken into account, it is anticipated that 0.3 mm PPLG is an effective material for dosimetry. The results of these lines of research are intended to educate the innovation of versatile graphite radiation dosimeters as a low-cost efficient system for radiation detection. The studied PPLG offers tissue equivalence as well as high spatial resolution, both are desirable criteria for a material to be used in the monitoring of ionising radiation or a variety of medical applications.

    Yehia H. Johary, Sultan Albarakati, Abdullah AlSohaim, Ali Aamry, Hussin Aamri, N. Tamam, Hassan Salah, Dahlang Tahir, Mohammed Alkhorayef, Abdelmoneim Sulieman, David Bradley (2023)Evaluation occupationally radiation exposure during diagnostic imaging examinations, In: Applied radiation and isotopes193pp. 110648-110648 Elsevier

    Occupational radiation exposure can occur due to various human activities, including the use of radiation in medicine. Occupationally exposed personnel surpassing 7.4 millions, and respresent the biggest single group of employees who are exposed to artificial radiation sources at work. This study compares the occupational radiation dose levels for 145 workers in four different hospitals located in the Aseer region in Saudi Arabia. The occupational exposure was quantified using thermoluminescence dosimeters (TLD-100). The levels of annual occupational exposures in targeted hospitals were calculated and compared with the levels of the international atomic energy agency (IAEA) Safety Standards. An average yearly cumulative dose for the two consecutive years. The average, highest and lowest resulted occupational doses under examination in this work is 1.42, 3.9 mSv and 0.72 for workers in various diagnostic radiology procedures. The resulted annual effective dose were within the IAEA approved yearly dose limit for occupational exposure of workers over 18, which is 20 mSv. Staff should be monitored on a regular basis, according to current practice, because their annual exposure may surpass 15% of the annual effective doses.

    F Moradi, Kh Saraee, D A Bradley (2021)Skin dose assessment at diagnostic and therapeutic photon energies: A Monte Carlo study on TLDs, In: Radiation physics and chemistry (Oxford, England : 1993)185 Elsevier BV

    In radiotherapy but also as a part of quality assurance in diagnostic imaging, assessment of radiation dose to the skin of the patient is of particular importance. While skin dose is recommended to be measured at a reference depth of 70 μm, in practice in both diagnostic radiology as well as therapeutic applications, the dosimeter is placed on the skin surface, the measured dose depending in large part on dosimeter thickness. Thermoluminescent dosimeters (TLDs) are commonly applied as skin dosimeters, most of the commercial forms being thicker than 140 μm, also with a density greater than that of soft tissue, accordingly representing in effective point of measurement deeper than 70 μm. On the other hand, Monte Carlo (MC) simulations can be used to accurately calculate the dose at an intended depth. In this work we first validate our MC simulations, comparison being made with a previously published correction factor for LiF TLD of dimensions 3 × 3 × 0.1 mm3. Then correction factors to convert the dose measured by various commercial LiF-based TLDs (with thicknesses ranging from 0.15 to 1 mm) to skin dose at 70 μm depth are calculated for RQR reference diagnostic photon spectra and some common MV photon therapy spectra. These results are useful for correction of TLD responses in various clinical situations.

    Amir Entezam, Andrew Fielding, Davide Moi, David Bradley, Gishan Ratnayake, Lucy Sim, Chelsea Kralik, Davide Fontanarosa (2021)Investigation of scattered dose in a mouse phantom model for pre-clinical dosimetry studies, In: Radiation physics and chemistry (Oxford, England : 1993)189 Elsevier Ltd

    Tissue-equivalent phantoms are suitable tools for radiation dosimetry investigations. The goal of this study was to determine the scattered dose in a simple phantom model of a mouse with a xenographic tumour using experimental dose measurements and Monte-Carlo calculations. We manufactured a cubic polymethyl methacrylate (PMMA) phantom with an extrusion on its side to model both normal tissue and xenograft tumour of a tumour-bearing mouse. The phantom was positioned in a novel add-on collimator, designed by our research group, to enable targeted irradiation of the xenograft tumour with a dose of 20 Gy using a137Cs gamma irradiator. EBT3 GAFchromic film was utilized to measure the dose distribution within the phantom. EGSnrc MC code was used to simulate the irradiation system and to calculate the dose distribution in the phantom for comparison with the film dose measurements. Good agreement was observed between film dose measurements and simulation results based on gamma index analysis. The results demonstrate that the out of field dose (dose to the normal tissue) is of the order 8–9% of the prescribed dose when irradiating the xenographic tumour of the phantom. Our physical phantom is a useful tool to assess the out of field dose when irradiating xenographic tumours. •A mouse phantom with a xenographic tumour was manufactured for dosimetry.•Out of field dose was determined when irradiating the xenographic tumour model.•Monte Carlo modelling of the phantom irradiation was created for dose calculation.•Gamma analysis was used to compare the measured and calculated dose profiles.

    Md Salah Uddin Afsar, Mohammad Rashed Iqbal Faruque, Mayeen Uddin Khandaker, Amal Alqahtani, David A. Bradley (2022)A New Compact Split Ring Resonator Based Double Inverse Epsilon Shaped Metamaterial for Triple Band Satellite and Radar Communication, In: Crystals (Basel)12(4) Mdpi

    This study presents a double-inverse-epsilon-shaped, triple-band epsilon-negative (ENG) metamaterial with two split ring resonators (SRRs). The proposed unit cell comprises a single slit two SRRs with two inverse-epsilon-shaped metal bits. Rogers RT6002, of dimension 10 x 10 x 1.524 mm(3), is used as a substrate. An electromagnetic simulator CST microwave studio is used to investigate the effective medium parameters of the material. The proposed metamaterial shows three resonance peaks that are demarcated at the frequencies 2.38 GHz, 4.55 GHz and 9.42 GHz consecutively. The negative permittivity of the metamaterial is observed at the frequency ranges of 2.39-2.62 GHz, 4.55-4.80 GHz and 9.42-10.25 GHz. The goodness of the material was presented by the effective medium ratio (EMR) of the unit cell at 12.61. In addition, the simulated results are authenticated by using different electromagnetic simulators such as HFSS and ADS for the equivalent circuit model, which exhibits insignificant disparity. The anticipated scheme was finalised through some parametric analyses, together with configuration optimisation, different unit cell dimensions, several substrate materials, and altered electromagnetic (EM) field transmissions. The proposed triple band (S-, C- and X-bands) with negative permittivity (epsilon) metamaterial is practically used for numerous wireless uses, for instance, far distance radar communication, satellite communication bands and microwave communication.

    Mayeen Uddin Khandaker, Siti Nurasiah Mat Nawi, David Andrew Bradley, Siok Ee Lam, Siti Fairus Abdul Sani, Abdelmoneim Sulieman (2021)Studies of thermoluminescence kinetic parameters of polymer pencil lead graphite under photon exposures, In: Applied radiation and isotopes174pp. 109757-109757 Elsevier Ltd

    This study analysed thermoluminescence (TL) glow curves of the polymer pencil lead graphite (PPLG) due to its potential applications in radiation dosimetry. The TL glow curves provide information on the physical parameters of the defects participating in luminescence process. The glow curves for different diameters PPLG samples were obtained with varying temperature from 50 to 300 °C, at a fixed heating rate of 10 °Cs−1. A number of methods (initial rise, peak shape and curve fitting) were used to fit the TL glow peaks of the PPLG samples obtained under photon dose of 200 Gy. From the fitted TL signals, the trap parameters such as the order of kinetics, the activation energy, the frequency factor, etc. for the individual peaks were numerically determined. The lifetimes of TL process were calculated assuming the first-order kinetics. The results are compared among the different methods adopted in this study. Implications about the possible results in glow curve deconvolution are discussed. •Novel use of polymer pencil-lead graphite (PPLG) for radiation dosimetry.•TL Kinetic parameters of PPLG are studied for the first time using various techniques.•Principal trapping parameters are evaluated and compared among different methods.•The data suggest that the TL glow peaks of the PPLG obey general-order kinetics.

    M.S.A. Fadzil, N.M. Noor, N. Tamchek, N.M. Ung, N. Abdullah, M.T. Dolah, D.A. Bradley (2022)A cross-validation study of Ge-doped silica optical fibres and TLD-100 systems for high energy photon dosimetry audit under non-reference conditions, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    This study compares the practicality of Ge-doped silica optical fibres as a potential remote dosimeter for radiotherapy postal dosimetry audit in non-reference conditions with a commercial thermoluminescence dosimeter (TLD-100). The optical fibre system consists of two types of fibres: cylindrical (CF) and flat fibres (FF). The dosimetric characteristics of the systems were investigated and compared, with particular attention to dose linearity, energy dependence, reproducibility, and fading. Measurements of absorbed doses of CF, FF, and TLD-100 were made, along with uncertainty budgets. A preliminary test was performed under non-reference conditions to evaluate the variations in absorbed doses measured with CF and FF versus TLD-100. For both 6 MV and 10 MV photon beams, CF, FF, and TLD-100 show a linear dose-response from 1 Gy to 3 Gy with a coefficient of determination (R2) greater than 0.99, minimal energy dependence, and good reproducibility with less than 3% deviation. The highest fading rates were 37.6%, 63.4%, and 14.2% for CF, FF, and TLD-100, respectively, at day 106 after irradiation. For irradiation with a photon beam of 6 MV, the combined relative standard uncertainty of absorbed dose determined from CF, FF, and TLD-100 measurements was estimated to be 4.3%, 5.56%, and 0.74%, respectively. Preliminary absorbed dose measurement tests under non-reference conditions showed that the mean ratios of Ge-doped silica optical fibres to TLD-100 for on-axis dose, wedge transmission, and output factor were 1.014, 0.991, and 1.013, respectively. The Ge-doped silica optical fibre systems have dosimetric performance commensurate with the TLD-100 and can be used as a potential remote dosimeter for mailed dosimetry audits if appropriate correction factors are applied to the absorbed dose measurements. •Ge-doped silica optical fibres and TLD-100 dosimetric properties were investigated.•The uncertainty analysis was performed on Ge-doped silica optical fibres and TLD-100.•The absorbed dose measured by Ge-doped silica optical fibres is comparable to TLD-100.•Ge-doped silica optical fibres provide reasonable accuracy as a remote dosimeter.

    H.T. Zubair, Mahfuza Begum, Farhad Moradi, A.K.M. Mizanur Rahman, Ghafour A. Mahdiraji, Adebiyi Oresegun, G.T. Louay, Nasr Y.M. Omar, Mayeen U. Khandaker, Faisal R. M. Adikan, Noramaliza M. Noor, K.S. Almugren, Hairul Azhar Abdul-Rashid, David A. Bradley (2020)Recent Advances in Silica Glass Optical Fiber for Dosimetry Applications, In: IEEE photonics journal12(3)pp. 1-25 IEEE

    In this paper, we review the highly promising silica glass, fabricated as doped and undoped optical fiber for intended use in radiation dosimetry. The dosimetry techniques reviewed here, underpinned by intrinsic and extrinsic defects in silica glass, focus on Thermoluminescence (TL), Optically Stimulated Luminescence (OSL) and Radioluminescence (RL), with occasional references to the much more established Radiation Induced Attenuation (RIA). The other focus in this review is on the various materials that have been reported earlier as dopants and modifiers used in silica glass optical fiber radiation dosimeters. This article also elaborates on recently reported optical fiber structures, namely, cylindrical fibers, photonic crystal fibers and flat fibers, as well as dimensions and shapes used for optimization of dosimeter performance. The various types of optical fiber radiation dosimeters are subsequently reviewed for various applications ranging from medical dosimetry such as in external beam radiotherapy, brachytherapy and diagnostic imaging, as well as in industrial processing and space dosimetry covering a dynamic dose range from μGy to kGy. Investigated dosimetric characteristics include reproducibility, fading, dose response, reciprocity between luminescence yield to dose-rate and energy dependence. The review is completed by a brief discussion on limitations and future developments in optical fiber radiation dosimetry.

    Adebiyi Oresegun, A. Basaif, Zubair H. Tarif, H. A. Abdul-Rashid, Siti Aiasah Hashim, D. A. Bradley (2021)Radioluminescence of silica optical fibre scintillators for real-time industrial radiation dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier

    Dosimetry systems are important in any radiation facility to ensure quality, safety, validation, qualification and quality control of established and new processes, including at industrial radiation facilities. We present a study of silica optical fibre as scintillators for industrial radiation dosimetry using Radioluminescence (RL). The RL technique provides for a remote and real-time dosimetry measurement in such a high dose environment. This study establishes the dosimetric characteristics of two variants of pure silica optical fibre, low and high hydroxyl (OH) when exposed to industrial radiation levels. The samples were exposed to a linear accelerator, with doses in the order of tens of kGy (from 10 kGy through to 70 kGy in individual exposures). The performance parameters observed during the study include the RL emission spectrum, emission intensity and emission linearity with exposure dose. The RL spectrum demonstrated a central wavelength of 650 nm and 550 nm for the high and low OH scintillators, respectively. RL intensity was observed to increase with exposed dose, a result of recombination of ionizing radiation generated electron-hole pairs. The RL intensity relation with exposed dose indicated a linear response, with the higher OH sample showing the greater slope, indicating greater sensitivity. The overall results indicate the potential use of pure silica optical fibre as scintillators for remote and real-time industrial radiation dosimetry.

    Jane K. L. Teh, David A. Bradley, Jack Bee Chook, Kee Huong Lai, Woo Teck Ang, Kok Lay Teo, Suat-Cheng Peh (2021)Multivariate visualization of the global COVID-19 pandemic: A comparison of 161 countries, In: PloS one16(5)pp. e0252273-e0252273 Public Library Science

    Background The aim of the study was to visualize the global spread of the COVID-19 pandemic over the first 90 days, through the principal component analysis approach of dimensionality reduction. Methods This study used data from the Global COVID-19 Index provided by PEMANDU Associates. The sample, representing 161 countries, comprised the number of confirmed cases, deaths, stringency indices, population density and GNI per capita (USD). Correlation matrices were computed to reveal the association between the variables at three time points: day-30, day-60 and day-90. Three separate principal component analyses were computed for similar time points, and several standardized plots were produced. Results Confirmed cases and deaths due to COVID-19 showed positive but weak correlation with stringency and GNI per capita. Through principal component analysis, the first two principal components captured close to 70% of the variance of the data. The first component can be viewed as the severity of the COVID-19 surge in countries, whereas the second component largely corresponded to population density, followed by GNI per capita of countries. Multivariate visualization of the two dominating principal components provided a standardized comparison of the situation in the161 countries, performed on day-30, day-60 and day-90 since the first confirmed cases in countries worldwide. Conclusion Visualization of the global spread of COVID-19 showed the unequal severity of the pandemic across continents and over time. Distinct patterns in clusters of countries, which separated many European countries from those in Africa, suggested a contrast in terms of stringency measures and wealth of a country. The African continent appeared to fare better in terms of the COVID-19 pandemic and the burden of mortality in the first 90 days. A noticeable worsening trend was observed in several countries in the same relative time frame of the disease's first 90 days, especially in the United States of America.

    A. N. Edam, A. Sulieman, A. K. Sam, I. Salih, M. Alkhorayef, D. A. Bradley (2020)Quality control of radiopharmaceuticals and diagnostic nuclear medicine equipment, In: Radiation physics and chemistry (Oxford, England : 1993)167 Elsevier

    Quality control (QC) in nuclear medicine (NM) is used to detect deterioration or irregularities with respect to the imaging device (e.g. the gamma camera), the dose calibrator, or the radiopharmaceutical. National Regulatory Authority (RA) regulations and requirements have an essential role to play in improving diagnostic image quality (IQ) and reduction of radiation dose to patients. To-date, little attention has been given to IQ and instrument QC in Sudan, including gamma cameras, dose calibrators, and radiopharmaceuticals. The aim of the present work was to evaluate the current QC application status of NM equipment and radiopharmaceuticals in Sudan. All existing five NM Departments in the country were included in this survey and data was collected using a questionnaire. The survey data showed that for gamma cameras and radiopharmaceuticals, the level of implementation for the recommended QC tests was 60% and 35%, respectively, and as such they are not fully compliant with international recommendations. Dose calibrators, however, were complying with the international QC recommendations (75%). These results highlight the need for awareness and training programmes in IQ and patient dose control. The study concludes that the operation of NM equipment in the country is inadequate and does not ensure good quality images for diagnosis, patients also potentially receiving unnecessary radiation dose due to the lack of a proper QC program. Compliance with the national RA regulations is necessary to improve IQ and seek optimum patient dose.

    M.F. Hassan, W.N. Rahman, T. Akagi, N.S. Sulaiman, D.A. Bradley, N.M. Noor (2023)Thermoluminescence kinetic parameters of proton-irradiated germanium doped flat-shape optical fibres, In: Radiation physics and chemistry (Oxford, England : 1993)202 Elsevier Ltd

    Glow curve is a key element in thermoluminescence (TL) studies as it provides on-the-ground understanding on the trapping mechanism inside the crystal lattice and hence stability of the TL material. In the present work, luminescence mechanism of the in-house fabricated germanium doped (Ge-doped) flat-shape silica optical fibres have been investigated following irradiation by 150-MeV proton beams. Results of TL dose-response showed that there is a linear relationship between TL response and proton doses from 1 to 10 Gy, with a coefficient of determination close to one. The structure of glow curve remains unchanged throughout the studied dose range with a maximum glow peak dominated at temperature of within 250–290 °C. A Tmax-Tstop plot reveals not only horizontal regions but also smooth slopes, indicative of the presence of a continuum distribution of glow peaks and trap depth. A computerised glow curve deconvolution analysis of the respective fibre glow-curves demonstrated that they were composed of five strongly overlapping peaks underlying a broad TL spectrum, obtaining figures of merit in the range of 0.56–1.64%. The main physical kinetic parameters (activation energy and frequency factor) of the fitted glow peaks were obtained using GlowFit software. The data suggest that the TL glow peaks of the Ge-doped silica optical fibres obey second-order kinetics. •The fabricated Ge-doped optical fibres provide excellent dose response to proton beam.•Tmax-Tstop reveals the existence of quasi-continuous distribution of peaks and traps.•Five closely overlapping peaks are obtained via computerised glow curve deconvolution.•TL glow peaks of the Ge-doped optical fibres obey second-order kinetics.

    Ibrahim Gaafar, Mona Elbarbary, M. I. Sayyed, Abdelmoneim Sulieman, Nissren Tamam, Mayeen Uddin Khandaker, David A. Bradley, Mohamed. Y. Hanfi (2022)Assessment of Radioactive Materials in Albite Granites from Abu Rusheid and Um Naggat, Central Eastern Desert, Egypt, In: Minerals (Basel)12(2) Mdpi

    The present study aims to assess Abu Rusheid and Um Naggat albite granite's natural radioactivity in the Central Eastern Desert, Egypt, using an HPGe laboratory spectrometer. A total of 17 albite granite samples were detected for this study. The activity concentrations were estimated for U-238 (range from 204 to 1127 Bq/kg), Ra-226 (range from 215 to 1300 Bq/kg), Th-232 (from 130 to 1424 Bq/kg) and K-40 (from 1108 to 2167 Bq/kg) for Abu Rusheid area. Furthermore U-238 (range from 80 to 800 Bq/kg), Ra-226 (range from 118 to 1017 Bq/kg), Th-232 (from 58 to 674 Bq/kg) and K-40 (from 567 to 2329 Bq/kg) for the Um Naggat area. The absorbed dose rates in the outdoor air were measured with average values of 740 nGy/h for Abu Rusheid albite granite and 429 nGy/h for Um Naggat albite granite. The activity concentration and gamma-ray exposure dose rates of the radioactive elements U-238, Ra-226, Th-232 and K-40 at Abu Rusheid and Um Naggat exceeded the worldwide average values that recommend the necessity of radiation protection regulation. Moreover, the corresponding outdoor annual effective dose (AED(out)) was calculated to be 0.9 and 0.5 mSv y(-1) for Abu Rusheid and Um Naggat albite granite, respectively, which are lower than the permissible level (1 mSv y(-1)). By contrast, the indoor annual effective dose (AED(in)) exceeded the recommended limit (3.6 and 2.1 for Abu Rusheid and Um Naggat, respectively). Therefore, the two areas are slightly saving for development projects concerning the use of the studied rocks. The statistical analysis displays that the effects of the radiological hazard are associated with the uranium and thorium activity concentrations in Abu Rusheid and Um Naggat albite granites.

    A. Bushra, A. Sulieman, A. Edam, N. Tamam, E. Babikir, N. Alrihaima, E. Alfaki, S. Babikir, A. Almujally, Ahmed Otayni, M. Alkhorayef, A. Abdelradi, D.A. Bradley (2023)Patient's effective dose and performance assessment of computed radiography systems, In: Applied radiation and isotopes193pp. 110627-110627 Elsevier Ltd

    Computed tomography is widely used for planar imaging. Previous studies showed that CR systems involve higher patient radiation doses compared to digital systems. Therefore, assessing the patient's dose and CR system performance is necessary to ensure that patients received minimal dose with the highest possible image quality. The study was performed at three medical diagnostic centers in Sudan: Medical Corps Hospital (MCH), Advance Diagnostic Center (ADC), and Advance Medical Center (AMC). The following tools were used in this study: Tape measure, Adhesive tape, 1.5 mm copper filtration (>10 × 10 cm), TO 20 threshold contrast test object, Resolution test object (e.g., Huttner 18), MI geometry test object or lead ruler, Contact mish, Piranha (semiconductor detector), Small lead or copper block (∼5 × 5 cm), and Steel ruler, to do a different type of tests (Dark Noise, Erasure cycle efficiency, Sensitivity Index calibration, Sensitivity Index consistency, Uniformity, Scaling errors, Blurring, Limiting spatial Resolution, Threshold, and Laser beam Function. Entrance surface air kerma (ESAK (mGy) was calculated from patient exposure parameters using DosCal software for three imaging modalities. A total of 199 patients were examined (112 chest X rays, 77 lumbar spine). The mean and standard deviation (sd) for patients ESAK (mGy) were 2.56 ± 0.1 mGy and 1.6 mGy for the Anteroposterior (AP) and lateral projections for the lumbar spine, respectively. The mean and sd for the patient's chest doses were 0.1 ± 0.01 for the chest X-ray procedures. The three medical diagnostic centers' CR system performance was evaluated and found that all of the three centers have good CR system functions. All the centers satisfy all the criteria of acceptable visual tests. CR's image quality and sensitivity were evaluated, and the CR image is good because it has good contrast and resolution. All the CR system available in the medical centers and upgraded from old X-ray systems to new systems, has been found to work well. The patient's doses were comparable for the chest X-ray procedures, while patients' doses from the lumbar spine showed variation up to 2 folds due to the variation in patients' weight and X-ray machine setting. Patients dose optimization is recommended to ensure the patients received a minimal dose while obtaining the diagnostic findings. •Computed radiography system performance were evaluated at three hospitals in Sudan.•Patients ESAK (mGy) was quantified for chest X rays and lumber spine procedures.•CR systems performance was acceptable and within the predefined limits.•The ESAK (mGy) was lower compared to previous published studies.

    Nurul Absar, Jainal Abedin, Md Mashiur Rahman, Moazzem Hossain Miah, Naziba Siddique, Masud Kamal, Mantazul Islam Chowdhury, Abdelmoneim Adam Mohamed Sulieman, Mohammad Rashed Iqbal Faruque, Mayeen Uddin Khandaker, David Andrew Bradley, Abdullah Alsubaie (2021)Radionuclides Transfer from Soil to Tea Leaves and Estimation of Committed Effective Dose to the Bangladesh Populace, In: Life (Basel, Switzerland)11(4) Mdpi

    Considering the probable health risks due to radioactivity input via drinking tea, the concentrations of Ra-226, Th-232,K-40 and Cs-137 radionuclides in the soil and the corresponding tea leaves of a large tea plantation were measured using high purity germanium (HPGe) gamma-ray spectrometry. Different layers of soil and fresh tea leaf samples were collected from the Udalia Tea Estate (UTE) in the Fatickchari area of Chittagong, Bangladesh. The mean concentrations (in Bq/kg) of radionuclides in the studied soil samples were found to be 34 +/- 9 to 45 +/- 3 for Ra-226, 50 +/- 13 to 63 +/- 5 for Th-232, 245 +/- 30 to 635 +/- 35 for K-40 and 3 +/- 1 to 10 +/- 1 for Cs-137, while the respective values in the corresponding tea leaf samples were 3.6 +/- 0.7 to 5.7 +/- 1.0, 2.4 +/- 0.5 to 5.8 +/- 0.9, 132 +/- 25 to 258 +/- 29 and

    M.Y. Hanfi, Bahaa M. Emad, M.I. Sayyed, Mayeen Uddin Khandaker, D.A. Bradley (2021)Natural radioactivity in the prospecting tunnel in Egypt: Dose rate and risk assessment, In: Radiation physics and chemistry (Oxford, England : 1993)187 Elsevier Ltd

    Uranium, apparently the most important item of heavy minerals, gains appropriate prominence in nuclear application. The present study divided into two parts is the occupational exposure contributed from the granitic rocks inside the prospecting tunnel as well as the public exposure associated with the extraction of raw materials that may be used in the infrastructure and other their activities. In the present study, the samples are distributed regularly inside various drafts of the prospecting tunnel (El-Missikat). A portable gamma spectrometry was used to detect the content of primordial radionuclides are associated with the granites (each of the sample being of the same geometry approximately). The results showed the mean activity concentrations of 238U, 232Th and 40K are higher than the recommended worldwide average at all monitoring stations in the tunnel. Three radiological indices: radium equivalent (Raeq) activity, absorbed dose rate (Dair), outdoor annual effective dose (AEDO) were detected based on the activity concentration of radionuclide in the tunnel. The annual effective dose was contributed from gamma radiation is 1.98 mSv that is lower than the recommended limit of 20 mSv, so no significant dose. While the public exposure for a long time for the extracted raw material can because a serious health effect. This is owing to the mean annual effective dose value (1.2 mSv) is a comparable to the recommended limit (1 mSv). •Natural radioactivity characterization of El-Missikat tunnel Egypt, was performed.•Radiological hazard indexes were calculated and assessed the risk assessment.•Significant natural radiation hazard comes from the studied granites.

    M.F. Hassan, W.N.W.A. Rahman, T. Tominaga, M. Geso, H. Akasaka, D.A. Bradley, N.M. Noor (2019)Ge-doped silica fibre for proton beam dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)165 Elsevier Ltd

    An investigation has been made of nominal 2.3 mol% and 6.0 mol% germanium (Ge) doped cylindrical optical fibres as novel radiation dosimeters for 150-MeV proton beam measurements. These optical fibres were locally fabricated using a modified chemical vapour deposition technique with a subsequent pulling process. Combined scanning electron microscope and energy dispersive X-ray spectroscopy analyses were performed to map the relative presence of the germanium and other elements in the optical fibres. Prior to irradiation, a thermal annealing process was carried out to erase any pre-irradiation signals potentially existing in the samples. Results were compared against nanoDot™, TLD-100, and commercial optical fibres to allow for a relative comparison of the response. For radiation dose in the range 1 up to 10 Gy, the fabricated optical fibres exhibit excellent radiation dose response (R2 > 0.99), with a linearity index that remains close to one (indicating a linear response). In terms of minimum detectable dose, these optical fibres are able to detect relatively low radiation dose (for the present batch of fibres down to 10.7 mGy). After repeated various irradiation campaigns, the fabricated optical fibres have been shown to provide consistent response, effectively without noticeable change in thermoluminescence (TL) yield (ANOVA, p > 0.05), suggesting excellent reproducibility. In regard to signal fading, 96 days post-irradiation the fabricated optical fibres showed minimal signal loss, at 19% at the most. These dosimetric characteristics confirm the potential of the fabricated optical fibres as TL dosimeters, specifically for present studies in conducting proton beam measurements. •The fabricated Ge-doped optical fibres provide excellent dose response to proton beam.•Minimal nonlinearity is observed particularly in the low-dose regions.•Fibres responses are reproducible after repeat irradiations under various conditions .•The minimum detectable dose for the fibres has shown to be down to miligray levels .•The fibres experience a minimal signal fading rate after 96 days of post-irradiation .

    Mayeen Uddin Khandaker, Onosohwo Bemigho Uwatse, Khairi Azri Bin Shamsul Khairi, M. R. I. Faruque, D. A. Bradley (2019)TERRESTRIAL RADIONUCLIDES IN SURFACE (DAM) WATER AND CONCOMITANT DOSE IN METROPOLITAN KUALA LUMPUR, In: Radiation protection dosimetry185(3)pp. 343-350 Oxford Univ Press

    Batu Dam is of considerable importance to the metropolis of Kuala Lumpur, its existence and the quality assessment of its waters being essential in helping to maintain the lives of a large sector of the Malaysian population. Concerning the level of naturally occurring radioactivity contained within its waters, a well characterised HPGe gamma-ray technique has been used in making measurements of the concentrations of primordial radionuclides in samples of surface water from the Dam. Based on the mean individual daily consumption of dam water, estimation has been made of the concomitant radiation dose. Activity concentrations, in units of Bq l(-1), have been found to be in the range 2.4-3.2 for Ra-226, 1.1-1.3 for Th-232 and 22.7-40.7 for K-40, in line with literature data for surface waters. The total annual ingestion dose for infants (

    F. Moradi, S.F. Abdul Sani, M.H. Norazri, N.M. Ung, K.S. Almugren, Kh.Rezaee Ebrahim Saraee, D.A. Bradley (2022)Evaluation of perturbation effects for various size TLDs in small field dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    Small field treatments in radiotherapy have been increasingly developed during the last years due to the potential to produce more conformal dose in the target volume and to enhance the therapeutic ratio. On the other hand, dosimetric task for small field techniques is more challenging because of the production of small dimension high dose areas with rapid dose rate fall off margins. Dosimetry of such small fields necessitate a significant decrease in the size of routine radiation dosimeters. In this work we look at the effect of dosimeter size on the perturbation effect caused by the presence of the dosimeter in the radiation field. Monte Carlo simulations were used to characterize the radiation field and obtain distribution of energy deposition in a water phantom. Changes in electron spectra within various size (LiF and SiO2) TLDs in different size radiation fields 10 × 10 cm2, 2 × 2 cm2 and 0.5 × 0.5 cm2 were investigated and perturbation effect caused by the presence of dosimeter was observed. The results showed significant perturbations produced by conventional LiF TLDs that is especially important in small radiation fields. The use of small size silica fibre (SiO2) TL dosimeters for application in small field dosimetry was observed to be reasonably advantageous. Based on the simulation results, cylindrical silica fibres with 0.5 mm diameter do not produce a significant perturbation in the 10 × 10 cm2, 2 × 2 cm2 fields. The perturbation in the field by 0.125 mm diameter silica fibre was observed to be negligible even in 0.5 × 0.5 cm2 radiation field. •High spatial resolution is the most important factor for a dosimeter in small field dosimetry.•Monte Carlo simulations were used to evaluate perturbation effect of TLDs in small fields.•Perturbation of LiF and SiO2 TLDs in 10 × 10, 2 × 2 and 0.5 × 0.5 cm2 fields were compared.•Results show considerable perturbation caused by conventional LiF TLDs in small fields.•Miniaturized silica fibre TLDs were shown to be advantageous for small field dosimetry.

    Halmat Jalal Hassan, Suhairul Hashim, Mohamad Syazwan Mohd Sanusi, Mohamad Hidayat Jamal, Sitti Asmah Hassan, David Andrew Bradley, Rafael Garcia-Tenorio, Rozman Mohd Tahar (2021)The naturally occurring radioactivity of 'scalar energy' pendants and concomitant radiation risk, In: PloS one16(6)pp. e0250528-e0250528 Public Library Science

    Forming part of a study of radiological risk arising from use of radioactive consumer products, investigation is made of pendants containing naturally occurring radioactive material. Based on use of gamma-ray spectrometry and Monte Carlo (MC) simulations, the study investigates commercially available 'scalar energy pendants'. The doses from these have been simulated using MIRD5 mathematical phantoms, evaluation being made of dose conversion factors (DCFs) and organ dose. Metallic pendants code MP15 were found to contain the greatest activity, at 7043 +/- 471 Bq from Th-232, while glass pendants code GP11 were presented the greatest U-238 and K-40 activity, at 1001 +/- 172 and 687 +/- 130 Bq respectively. MP15 pendants offered the greatest percentage concentrations of Th, Ce, U and Zr, with means of 25.6 +/- 0.06, 5.6 +/- 0.005, 1.03 +/- 0.04 and 28.5 +/- 0.08 respectively, giving rise to an effective dose of 2.8 mSv for a nominal wearing period of 2000 h. Accordingly, these products can give rise to annual doses in excess of the public limit of 1 mSv.

    Z. Siti Rozaila, Mayeen Uddin Khandaker, Norfadira Binti Wahib, Mohd Khairul Hanif bin Abdul Jilani, S. F. Abdul Sani, D. A. Bradley (2020)Thermoluminescence characterization of smartphone screen for retrospective accident dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)167 Elsevier

    With increasing use of ionizing radiation and associated nuclear materials, concern arises regarding the possibility of harm from unplanned events, both to the surrounding environment as well as to its inhabitants; the Three Mile Island, Chernobyl and Fukushima Daiichi nuclear power plant incidents come to mind. Retrospective dosimetry can provide estimation of the radiation dose received from such accidents, the information allowing appropriate remedial measures to be formulated. In the affected area a number of objects can be applied as natural dosimeters. Given that the mobile phone is a device used by a large fraction of the population, investigation has been made of the suitability of the phone screen for retrospective dosimetry. Samples of five brands of phone screen were studied (Iphone, Sony, Samsung, Asus and Xiomi), investigating key thermoluminescence (TL) properties, including TL dose response, glow curves, reproducibility and long-term stability of the TL signal. Within the gamma-radiation dose range up to 10 Gy, these parameters show the Iphone screen to offer best use as a suitable material for retrospective dosimetry. Reconstruction of absorbed dose is possible for a period of up to four weeks post-incident. One proviso concerns the ability to adequately correct for TL signal loss during this time.

    N N M Rais, D A Bradley, A Hashim, N M Isa, N D Osman, I Ismail, H A Hassan, N M Noor (2019)Dosimetric response of fabricated Ge-doped optical fibres in computed tomography RQT beam quality x-ray beams, In: Journal of radiological protection39(3)pp. N8-N18 IOP Publishing

    Novel germanium (Ge)-doped silica glass fibres tailor-made in Malaysia are fast gaining recognition as potential media for thermoluminescence (TL) dosimetry, with active research ongoing into exploitation of their various beneficial characteristics. Investigation is made herein of the capability of these media for use in diagnostic imaging dosimetry, specifically at the radiation dose levels typically obtained in conduct of Computed Tomography (CT). As a first step within such efforts, there is need to investigate the performance of the fibres using tightly defined spectra, use being made of a Philips constant potential industrial x-ray facility, Model MG165, located at the Malaysian Nuclear Agency Secondary Standards Dosimetry Lab (SSDL). Standard radiation beam qualities (termed RQT) have been established for CT, in accord with IEC 61267: 2003 and IAEA Technical Reports Series No. 457: 2007. A calibrated ionisation chamber has also been utilised, forming a component part of the SSDL equipment. The fabricated fibres used in this study are 2.3 mol% flat fibre (FF) of dimensions 643 × 356 m2 and 2.3 mol% cylindrical fibre (CF) of 481 m diameter, while the commercial fibre used is 4 mol% with core diameter of 50 m. The dopant concentrations are nominal preform values. The fibres have been irradiated to doses of 20, 30 and 40 milligray (mGy) for each of the beam qualities RQT 8, RQT 9 and RQT 10. For x-rays generated at constant potential values from 100 to 150 kV, a discernible energy-dependent response is seen, comparisons being made with that of lithium fluoride (LiF) thermoluminescence dosimeters (TLD-100). TL yield versus dose has also been investigated for x-ray doses from 2 to 40 mGy, all exhibiting linearity. Compared to TLD-100, greater sensitivity is observed for the fibres.

    Siti Nurasiah Mat Nawi, S. F. Abdul Sani, M. U. Khandaker, N. M. Ung, K. S. Almugren, F. H. Alkallas, D. A. Bradley (2020)Tailored Ge-doped fibres for passive electron radiotherapy dosimetry, In: PloS one15(7)pp. e0235053-e0235053 Public Library Science

    Study has been made of the thermoluminescence yield of various novel tailor-made silica fibres, 6 and 8 mol % Ge-doped, with four differing outer dimensions, comprised of flat and cylindrical shapes, subjected to electron irradiation. Main thermoluminescence dosimetric characteristics have been investigated, including the glow curve, dose response, energy dependence, minimum detectable dose, effective atomic number, linearity of index and sensitivity of the fibres. The studies have also established the uncertainties involved as well as the stability of response in terms of fading effect, reproducibility and annealing. In addition, dose-rate dependence was accounted for as this has the potential to be a significant factor in radiotherapy applications. The 6 and 8 mol % fibres have been found to provide highly linear dose response within the range 1 to 4 Gy, the smallest size flat fibre, 6 mol% Ge-doped, showing the greatest response by a factor of 1.1 with respect to the highly popular LiF phosphor-based medium TLD100. All of the fibres also showed excellent reproducibility with a standard deviation of < 2% and < 4% for 6 and 8 mol % Ge-doped fibres respectively. For fading evaluation, the smallest 6 mol% Ge-doped dimension flat fibre, i.e., 85 x 270 mu m displayed the lowest signal loss within 120 days post-irradiation, at around 26.9% also showing a response superior to that of all of the other fibres. Moreover, all the fibres and TLD-100 chips showed independence with respect to electron irradiation energy and dose-rate. Compared with the 8 mol% Ge-doped optical fibres, the 6 mol% Ge-doped flat optical fibres have been demonstrated to possess more desirable performance features for passive dosimetry, serving as a suitable alternative to TLD-100 for medical irradiation treatment applications.

    Yehia H. Johary, Ali Aamry, Sultan Albarakati, Abdullah AlSohaim, Hussin Aamri, Nissren Tamam, Abdelmoneim Sulieman, Hiba Omer, Esameldeen Babikir, Mayeen Uddin Khandaker, David Bradley (2022)Staff radiation exposure at four radiology departments in the Aseer region of Saudi Arabia, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    Occupational exposure to ionizing radiation of medical personnel is very common at radiology and nuclear medicine departments. Strict regulations and guidelines for the exposure of staff working in such departments were regulated by international authorities such as the International Atomic Energy Agency (IAEA), and the International Commission on Radiological Protection (ICRP) as well as national protocols. In order to reduce stochastic effects, for example, radiation induced carcinogenesis, the exposure of staff working at nuclear medicine department should be maintained at levels lower than 20 mSv per year or 100 mSv in five years. The objective of this study is to measure staff radiation dose at four radiology departments in the south region of the Kingdom of Saudi Arabia. Exposures received by a total of 106 staff working at the radiology department were monitored for two consecutive years using calibrated Thermoluminecnt dosimeters (LiF:Mg:Ti (TLD-100). Exposure was then quantified in terms of deep dose: Hp (10). The TLD signal was obtained using an automatic TLD reader (Harshaw 6600). The overall annual dose for staff was 1.4 ± 0.37 (0.67–8.74). The study revealed that the annual radiation exposure in the four-radiology department is below the annual dose limits. However, staff doses could be reduced if proper radiation protection are followed. •Staff annual radiation dose were assessed for radiology technologists for two consecutive years.•Occupational doses were quantified with LiF: Mg, Ti (TLD-100).•90% of monitored staff received an annual occupational dose below 2.0 mSv.•Radiology technologists are well protected against occupational exposure.

    N. Z. H. Abu Hanifah, S. Hashim, Halmat J. Hassan, M. R. F. Abdul Hadi, M. S. M. Sanusi, D. A. Bradley, R. Garcia-Tenorio, R. M. Tahar (2022)Radiation hazard assessment from NORM-added paint products in Malaysia, In: Journal of King Saud University. Science34(3) Elsevier

    Introduction: Across the globe, radioactive consumer products are widely marketed for daily use. Objectives: The present study investigated commercially available ion paint, and the evaluations were using gamma (c)-ray spectroscopy and Geant4 Monte Carlo (GMC) simulations. Methods: An assessment of a radiological risk arising from using such products in the painting of living areas is conducted when Technologically Enhanced Naturally Occurring Radioactive Material (TENORM) was observed, with a daily inhalation exposure dose being of particular concern. Organ doses were simulated using adult mathematical Medical Internal Radiation Dose 5 (MIRD5)-type phantoms, incorporating dose conversion factors (DCFs). Results: Results showed that a product sample code of IP04 contained the highest activity, i.e., 4449 +/- 530, 31888 +/- 2175, and 2963 +/- 405 Bq kg-1, for 238U, 232Th, and 40K, respectively. Contrarily, NP18 recorded the lowest, i.e., 16 +/- 2 and 30 +/- 5, Bq kg-1 of 238U and 232Th, respectively. The IP04 paint offered the most significant concentrations, with mean percentages of 0.026, 0.81, and 0.06 for 238U, 232Th, and 212Pb, respectively. Its use in a designated Room 1 had resulted in an annual effective dose of 1.53 mSv y-1, assuming an exposure for a period of 8 h day-1. Conclusion: In brief, using these ion paints could result in amounts that exceed the annual public dose limit of 1 mSv. (c) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (

    F. Bajuri, D. A. Bradley, S. Mustafa, N. Tamchek, F. F. Ahmad Saad, N. Mazlan, N. Mohd Noor (2022)Morphology and thermoluminescence characteristics of customised Ge-doped optical fibre under Am-Be neutron source as a potential to be used for space radiation detector, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier

    In the low Earth orbit (LEO) neutron particles exist from secondary radiations due to interactions of Galactic Cosmic Ray (GCR) or trapped protons in the Earth's inner radiation belt with the Earth's atmosphere or space object materials or the astronaut themselves. Apart from that, high energy neutrons produced during solar tivities may survive in the distance travelled to the Earth. For passive dosimetry in space, the presence neutrons should be considered. In this work, we focused on the capability of Customised Optical Fibres (CusOF) to detect the neutrons produced by 241AmBe neutron source. Also, the morphology of flat fibres (FF) was ana-lysed using scanning electron microscopy (SEM) and Electron Dispersive X-ray (EDX). From the SEM images, ImageJ software was employed to measure the area of the organic shaped core of the FF accurately. From the EDX results, it was found that the effective atomic number of CusOF were in the range of 13.40-15.25, similar human skeleton. Irradiation of CusOF to 241AmBe neutron source shows that at a distance of 0 cm and 15 cm from the source, CusOF had high coefficient of determination (R2) value of 0.95-0.99, better than that of TLD-100 and TLD-700, 0.86 and 0.92, respectively, at 0 cm. This shows that the CusOF has high potential to be used for neutron radiation detector.

    Lian-Kuang Lim, Seong-Ling Yap, D. A. Bradley (2018)Time-resolved characteristics of deuteron-beam generated by plasma focus discharge, In: PloS one13(1)pp. e0188009-e0188009 Public Library of Science

    The plasma focus device discussed herein is a Z-pinch pulsed-plasma arrangement. In this, the plasma is heated and compressed into a cylindrical column, producing a typical density of > 10 25 particles/m 3 and a temperature of (1–3) × 10 7 o C. The plasma focus has been widely investigated as a radiation source, including as ion-beams, electron-beams and as a source of x-ray and neutron production, providing considerable scope for use in a variety of technological situations. Thus said, the nature of the radiation emission depends on the dynamics of the plasma pinch. In this study of the characteristics of deuteron-beam emission, in terms of energy, fluence and angular distribution were analyzed. The 2.7 kJ plasma focus discharge has been made to operate at a pressure of less than 1 mbar rather than at its more conventional operating pressure of a few mbar. Faraday cup were used to determine deuteron-beam energy and deuteron-beam fluence per shot while CR-39 solid-state nuclear track detectors were employed in studying the angular distribution of deuteron emission. Beam energy and deuteron-beam fluence per shot have been found to be pressure dependent. The largest value of average deuteron energy measured for present conditions was found to be (52 ± 7) keV, while the deuteron-beam fluence per shot was of the order of 10 15 ions/m 2 when operated at a pressure of 0.2 mbar. The deuteron-beam emission is in the forward direction and is observed to be highly anisotropic.

    Alla G. Morozova, Tatiana M. Lonzinger, Vadim A. Skotnikov, Gennady G. Mikhailov, Yury Kapelyushin, Mayeen Uddin Khandaker, Amal Alqahtani, D. A. Bradley, M. I. Sayyed, Daria I. Tishkevich, Denis A. Vinnik, Alex V. Trukhanov (2022)Insights into Sorption-Mineralization Mechanism for Sustainable Granular Composite of MgO-CaO-Al2O3-SiO2-CO2 Based on Nanosized Adsorption Centers and Its Effect on Aqueous Cu(II) Removal, In: Nanomaterials (Basel, Switzerland)12(1) Mdpi

    Although copper is needed for living organisms at low concentrations, it is one of the pollutants that should be monitored along with other heavy metals. A novel and sustainable composite mineralizing sorbent based on MgO-CaO-Al2O3-SiO2-CO2 with nanosized adsorption centers was synthesized using natural calcium-magnesium carbonates and clay aluminosilicates for copper sorption. An organometallic modifier was added as a temporary binder and a source of inovalent ions participating in the reactions of defect formation and activated sintering. The sorbent-mineralizer samples of specified composition and properties showed irreversible sorption of Cu2+ ions by the ion exchange reactions Ca2+ Cu2+ and Mg2+ Cu2+. The topochemical reactions of the ion exchange 2OH(-) -> CO32-, 2OH(-) -> SO42- and CO32- -> SO42- occurred at the surface with formation of the mixed calcium-copper carbonates and sulfates structurally connected with aluminosilicate matrix. The reverse migration of ions to the environment is blocked by the subsequent mineralization of the newly formed interconnected aluminosilicate and carbonate structures.

    N. Abdullah, D. A. Bradley, A. Nisbet, Z. Kamarul Zaman, S. S. Deraman, N. Mohd Noor (2022)Dosimetric characteristics of fabricated germanium doped optical fibres for a postal audit of therapy electron beams, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier

    The dosimetric characteristics of germanium (Ge) doped optical fibres are investigated as a potential dosimetric alternative for electron beam therapy postal audits. The dosimetric characteristics of 6 mol% Ge-doped optical fibres fabricated as cylindrical fibres (CF) and flat fibres (FF) are established in terms of signal fading, linearity of dose-response, beam energy- and dose rate dependence. Pilot electron beam therapy audit study irradiations are made with a linear accelerator located at the Royal Surrey County Hospital, applying International Atomic Energy Agency (IAEA) standard irradiation procedures for reference and non-reference conditions. Results for the CF and FF show fading of 26% and 20% respectively at 120 days post-irradiation. For a 6 MeV electron beam the dose-response is observed to be linear over the dose range 1-3 Gy, the least determination coefficient, R2, being 0.985. The results of the electron beam therapy audit are within the tolerance limit of 5% recommended by the International Commission on Radiation Units and Measurements (ICRU) Report No. 24, with a maximum deviation of 4% for FF at a 6 MeV electron beam under non-reference conditions. In conclusion, the fabricated Ge-doped optical fibres are seen to offer suitability for use as an alternative dosimeter to TLD-100 in electron beam therapy postal audit.

    M. Rubio, J. E. Fernandez, D. A. Bradley (2020)Editorial Preface, In: Radiation physics and chemistry (Oxford, England : 1993)167 Elsevier
    S.E. Lam, D.A. Bradley, R. Mahmud, M. Pawanchek, H.A. Abdul Rashid, N. Mohd Noor (2019)Dosimetric characteristics of fabricated Ge-doped silica optical fibre for small-field dosimetry, In: Results in physics12pp. 816-826 Elsevier B.V

    We study 3 mm long germanium-doped (Ge-doped) silica fibres for small-field dosimetry, seeking to overcome spatial resolution and charged-particle disequilibrium issues, also any associated dose deviation from that of computerised treatment plan dose delivery. Investigation has been made of the thermoluminescent (TL) dependency of locally fabricated 6 mol% Ge-doped preforms subsequently made into cylindrical (CF) and flat fibres (FF), also commercial Ge-doped fibres (COMM), the dopant and mechanical strain created in fibres production providing the trapping levels generating the TL yield. A Perspex phantom was designed for study of angular dependency, fibres being positioned at angles ranging from 0° to 90° while a scanning electron microscopy with energy dispersive X-ray (SEM/EDX) analysis study allowed evaluation of relative Ge content of the three TL types. Flat Fibre dose repeatability was found to be similar to that for the commercial fibre (in the range 2%–6%), improving appreciably upon that for the cylindrical fibre (

    O.L. Tashlykov, M.I. Sayyed, K.A. Mahmoud, Mayeen Uddin Khandaker, D.A. Bradley, S.G. Vlasova (2021)Tailor made barium borate doped Bi2O3 glass system for radiological protection, In: Radiation physics and chemistry (Oxford, England : 1993)187 Elsevier Ltd

    The study presents a ternary glass series fabricated as a mixture of 60B2O3-(40-x)BaO-xBi2O3, x = 0, 2.5, and 5 wt%. The glass density was measured using the Archimedes method with Xylene as an immerse liquid. The fabricated glass samples' mechanical features and elastic moduli were evaluated utilizing the Makishima-Makenzie (M-M) model based on the fabricated glass chemical composition and density. The elastic moduli were varied in the range between 92.862 and 99.734, 71.142–81.750, 36.208–38.457, and 119.420–133.027 Gpa for Young, bulk, shear, and longitudinal moduli. Other mechanical properties like Poisson ratio, microhardness, fractal bond conductivity, and softening temperature were predicted based on the fabricated glass samples' elastic moduli. Moreover, experimental measurements were applied to evaluate the linear attenuation coefficient at energies 662, 1173, and 1332 keV. The experimental measurements were confirmed with the theoretical XCOM program. Monte Carlo N- particle transport code version 5, XCOM, and BXCOM programs were used to evaluate the fabricated glass samples' radiation shielding properties. •Four Bismuth abased barium borate were fabricated using the melt quenching method.•Samples density increased from 3.15 to 3.28 g/cm3 with raising the Bi2O3 ratio.•The elastic moduli predicted based on the Makishima-Mackenzie model.•The elastic moduli increased with the Gt while they decreased with the Vi values.•Glasses' shielding properties were enhanced with the BaO replacement.

    Ahmed Mahfuz Tamim, Mohammad Rashed Iqbal Faruque, Mayeen Uddin Khandaker, Mohammad Tariqul Islam, David Andrew Bradley (2021)Electromagnetic radiation reduction using novel metamaterial for cellular applications, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier

    Excessive exposure to radiation has an adverse impact on human health, as an increase in body temperature may damage human organs or tissues, including the brain, eyes, and skin. Hence, this study assessed the effect of overexposure of radiation on the human head by analysing specific absorption rate (SAR) and reduction of SAR through the use of novel metamaterial (MTM). The SAR reduction was performed for GSM 900 MHz and 1800 MHz bands. A high-frequency electromagnetic simulator was employed throughout this study. The SAR investigation was performed on the head model for three categories of usage, namely voice calling, messaging, and video calling. This study looked into the impact on SAR of various free space distances between mobile phone and head model. A novel electric field driven LC (ELC) resonator-based MTM was used to reduce SAR. Based on the properties of the tissue, the rate of tissue absorption escalated with an increase in radiated power, especially when the distance between head and mobile phone decreased. The study outcomes signified that MTM could decrease a significant amount of SAR. This is beneficial to protect the human body from harmful radiation, wherein the distance from the device in biological effect should be maintained.

    Denis A. Vinnik, Vladimir E. Zhivulin, Evgeny A. Trofimov, Svetlana A. Gudkova, Alexander Yu Punda, Azalia N. Valiulina, Maksim Gavrilyak, Olga V. Zaitseva, Sergey V. Taskaev, Mayeen Uddin Khandaker, Amal Alqahtani, David A. Bradley, M. I. Sayyed, Vitaliy A. Turchenko, Alex V. Trukhanov, Sergei V. Trukhanov (2022)A-Site Cation Size Effect on Structure and Magnetic Properties of Sm(Eu,Gd)Cr0.2Mn0.2Fe0.2Co0.2Ni0.2O3 High-Entropy Solid Solutions, In: Nanomaterials (Basel, Switzerland)12(1) Mdpi

    Three high-entropy Sm(Eu,Gd)Cr0.2Mn0.2Fe0.2Co0.2Ni0.2O3 perovskite solid solutions were synthesized using the usual ceramic technology. The XRD investigation at room temperature established a single-phase perovskite product. The Rietveld refinement with the FullProf computer program in the frame of the orthorhombic Pnma (No 62) space group was realized. Along with a decrease in the V unit cell volume from ~224.33 angstrom(3) for the Sm-based sample down to ~221.52 angstrom(3) for the Gd-based sample, an opposite tendency was observed for the unit cell parameters as the ordinal number of the rare-earth cation increased. The average grain size was in the range of 5-8 mu m. Field magnetization was measured up to 30 kOe at 50 K and 300 K. The law of approach to saturation was used to determine the M-s spontaneous magnetization that nonlinearly increased from ~1.89 emu/g (Sm) up to ~17.49 emu/g (Gd) and from ~0.59 emu/g (Sm) up to ~3.16 emu/g (Gd) at 50 K and 300 K, respectively. The M-r residual magnetization and H-c coercive force were also determined, while the SQR loop squareness, k magnetic crystallographic anisotropy coefficient, and H-a anisotropy field were calculated. Temperature magnetization was measured in a field of 30 kOe. ZFC and FC magnetization curves were fixed in a field of 100 Oe. It was discovered that the T-mo magnetic ordering temperature downward-curve decreased from ~137.98 K (Sm) down to ~133.99 K (Gd). The spin glass state with ferromagnetic nanoinclusions for all the samples was observed. The average and D-max maximum diameter of ferromagnetic nanoinclusions were calculated and they were in the range of 40-50 nm and 160-180 nm, respectively. The mechanism of magnetic state formation is discussed in terms of the effects of the A-site cation size and B-site poly-substitution on the indirect superexchange interactions.

    Halmat Jalal Hassan, Suhairul Hashim, Noor Zati Hani Abu Hanifah, Muhammad Fahmi Rizal Abdul Hadi, Mohamad Syazwan Mohd Sanusi, David Andrew Bradley, Rafael Garcia Tenorio, Rozman Mohd Tahar (2021)The Enhanced Naturally Occurring Radioactivity of Negative Ion Clothing and Attendant Risk, In: Applied sciences11(12) Mdpi

    The study investigates commercially available negative ion clothing, and evaluations are made using gamma-ray spectroscopy and Geant4 Monte Carlo simulations. Observed to contain naturally occurring radioactive material (NORM), evaluations are made of the radiological risk arising from the use of these as items of everyday wear, undergarments in particular. Organ doses from these were simulated using the MIRD5 mathematical female phantom, with the incorporation of dose conversion factors (DCFs). At 175 +/- 26, 1732 +/- 247, and 207 +/- 38 Bq, for U-238, Th-232, and K-40 respectively, item code S05 was found to possess the greatest activity, while item code S07 was shown to have the least activity, at 2 +/- 0.5 and 15 +/- 2 Bq, and again for U-238 and Th-232, respectively. Sample code S11 recorded least activity, at 29 +/- 5 Bq, for K-40. Among the clothing items, sample item code S05 offered the greatest concentrations of Th, U and Zr, with percentage means of 1.23 +/- 0.1, 0.045 +/- 0.001, and 1.29 +/- 0.1, respectively, giving rise to an annual effective dose of 1.57 mSv/y assuming a nominal wearing period of 24 h per day. Accordingly, the annual public dose limit of 1 mSv can be exceeded by their use.

    F. Moradi, S.F. Abdul Sani, M.U. Khandaker, A. Sulieman, D.A. Bradley (2021)Dosimetric evaluation of gold nanoparticle aided intraoperative radiotherapy with the Intrabeam system using Monte Carlo simulations, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    Radiosensitization using high atomic number nanoparticles (NPs) has been shown to be an effective method to enhance radiotherapy efficiency. The pathways by which NPs cause sensitization, are generally categorized as physical, chemical and biological effects. Specifically in the case of keV photon radiotherapy where the contribution of physical effects in radiosensitization mechanism is considerable, Monte Carlo (MC) simulations have been an efficient tool to predict the radioenhancement level and to calculate dose enhancement factor (DEF). To-date, several analytical, simulational and experimental studies have reported the radiosensitization effect of gold nanoparticles (GNPs) in various brachytherapy situations. In this work we report for the first time, the DEFs achievable in intraoperative radiotherapy through use of the Intrabeam system and its spherical applicators with addition of GNPs. The MCNPX Monte Carlo code was used for radiation transport and dose calculations. The results of macroscopic and microscopic analysis show that for the Intrabeam system and a homogeneous distribution of 50 nm diameter GNPs, respective DEFs of up to some 1.5, 2, 2.5 and 3 in the tumour bed can be achieved with 5, 10, 15 and 20 mg/g concentrations. Due to rapid change in electron spectra, DEFs greater than 1 mm separation from the applicator surface decrease with distance, offering an additional advantage. •Gold nanoparticles (GNPs) are potential radiosensitizers for use in brachytherapy.•MC simulation is a familiar approach in prediction of dose enhancement factor (DEF).•DEFs achievable using GNPs in Intrabeam system brachytherapy were estimated.•Macroscopic and microscopic analysis were performed on the MC results.•DEFs of 1.5, 2, 2.5 & 3 were obtained with 5, 10, 15 & 20 mg/g gold concentrations.

    Sabina Yasmin, Bijoy Sonker Barua, Mayeen Uddin Khandaker, Masud Kamal, Md Abdur Rashid, S.F. Abdul Sani, H. Ahmed, Bijan Nikouravan, D.A. Bradley (2018)The presence of radioactive materials in soil, sand and sediment samples of Potenga sea beach area, Chittagong, Bangladesh: Geological characteristics and environmental implication, In: Results in physics8pp. 1268-1274 Elsevier B.V

    Accurate quantification of naturally occurring radioactive materials in soil provides information on geological characteristics, possibility of petroleum and mineral exploration, radiation hazards to the dwelling populace etc. Of practical significance, the earth surface media (soil, sand and sediment) collected from the densely populated coastal area of Chittagong city, Bangladesh were analysed using a high purity germanium γ-ray spectrometer with low background radiation environment. The mean activities of 226Ra (238U), 232Th and 40K in the studied materials show higher values than the respective world average of 33, 36 and 474 Bq/kg reported by the UNSCEAR (2000). The deduced mass concentrations of the primordial radionuclides 238U, 232Th and 40K in the investigated samples are corresponding to the granite rocks, crustal minerals and typical rocks respectively. The estimated mean value of 232Th/238U for soil (3.98) and sediment (3.94) are in-line with the continental crustal average concentration of 3.82 for typical rock range reported by the National Council on Radiation Protection and Measurements (NCRP). But the tonalites and more silicic rocks elevate the mean value of 232Th/238U for sand samples amounting to 4.69. This indicates a significant fractionation during weathering or associated with the metasomatic activity in the investigated area of sand collection.

    A. Sulieman, A. Elnour, M.Z. Mahmoud, M. Alkhorayef, O. Hamid, D.A. Bradley (2020)Diagnostic reference level for computed tomography abdominal examinations: A multicentre study, In: Radiation physics and chemistry (Oxford, England : 1993)174 Elsevier Ltd

    Computed tomography (CT) represents one of the largest sources of medical diagnostic ionizing radiation exposures to patients. As with other radiological imaging procedures, optimization leading to adoption of diagnostic reference levels (DRL) is recommended, mitigating unnecessary exposure. Present study has made evaluation of patient exposures, seeking a national DRL in Sudan for several abdominal CT techniques. In a study involving 16 radiology departments, data were obtained in imaging of a total of 321 patients examined for issues associated wtith the abdomen and pelvis. Patient weight and age ranges were 65–75 kg and 18–70 years respectively. Observed have been abdomen and abdomen-pelvis dose length products (DLP) in the range 1331 mGy cm to 3172 mGy cm and 370 mGy cm to 1687 mGy cm, respectively. The mean and range of CTDIvol (in mGy) for the abdomen and abdomen-pelvis respectively were found to be 28.2 (3.0–13.0) and 26.0 (4.0–80.0). Patient doses were observed to vary both between departments and within the same department, wide variation in technical settings suggesting need for staff training in CT dose optimization techniques. The patient doses are found to be greater than those typically observed in other studies elsewhere. DRLs are proposed for all of the investigated CT procedures. •Radiation dose was measured for patients undergoing 3 different CT abdomen Examination.•Patient doses data from 16 CT modalities were collected.•Patients exposed to avoidable radiation dose from two type CT abdomen procedure.•DRLs are proposed for all of the investigated CT procedures.

    Faradiba Tsani Arif, Heryanto Heryanto, Abdelmoneim Sulieman, David A. Bradley, Dahlang Tahir (2023)Geopolymer cellulose-based composite Black Carbon (BC)/Fe/Cu/polyvinyl alcohol for eco-friendly apron X-ray, In: Radiation physics and chemistry (Oxford, England : 1993)207 Elsevier Ltd

    Composite geopolymer apron cellulose/black carbon (BC)/Fe–Cu/polyvinyl alcohol (PVA) has been successfully synthesized with variations in Fe–Cu (Cel/Bc I, Cel/Bc II, and Cel/Bc III) as shielding X-ray radiation by employing a simple approach characterized by Fourier Transform Infra-Red (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray mobile. The quantitative analysis of the FTIR spectrum using the Kramers-Kronig (K–K) relation was employed to analyze the optical properties, the refractive index (n), the extinction coefficient (k), real (ε1), and imaginary (ε2) of the dielectric function and the energy loss function. The analysis of XRD spectra demonstrated that the crystallite size decreases as the Fe concentration decreases in the composite's apron and the best radiation shielding characteristics are shown in the Cel/Bc III sample with a small crystallite size of 12.72 nm. The quantitative analysis of X-ray mobile showed that the absorption properties of Cel/Bc III by the attenuation coefficient 0.441 cm−1 is higher and more effective with a half value layer of 1.57 cm and mean free path of 2.26 cm, which is indicated as a new cellulose-based composite apron X-ray in future. •Geopolymer Cellulose-Based Composite for Eco-Friendly Apron X-Ray.•Surface morphology with stretched cellulose (elongated and crossed).•Crystallite size decreases as the Fe concentration decreases.•Best absorption is composite Cel/Bc III with attenuation coefficient 0.441 cm−1.•The half value layer of 1.57 cm and mean free path of 2.26 cm.

    Khalid Alzimami, Layal Jambi, Essam Mattar, Ahmed Alenezi, Abdulrahman Alfuraih, Hassan Salah, Mohammad Rabbaa, Mohammad Abuljoud, Khaled Alsafi, Abdullah Alsubaie, Abdelmoneim Sulieman, David A. Bradley (2022)Effective radiation doses in neck computed tomography scans, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    A significant source of ionizing radiation for medical use is computed tomography (CT). According to estimates, more than 84 million CT scans are carried out yearly in the US. Because the neck area contains several organs and tissues that are very sensitive to ionizing radiation, such as the thyroid gland, CT for the neck region is commonly done for a variety of clinical causes. This study's goal is to assess the patient doses to radiosensitive organs and effective doses received during the CT neck surgery in the pastAt Riyadh Care Hospital, a multislice CT (MSCT) system (Siemens Somatom Sensation, 64 slices/detector) was used to perform improved CT treatments on a total of 54 patients. Patient ages were 41.5–15.5 years old on average, with a wide variation (21–73). Using computer software based on Monte Carlo simulation, organ and effective dosages were assessed. The International Commission of Radiological Protection (ICRP) risk variables were used to calculate the patient's radiogenic risk for a particular organ. The patients' dose length product (DLP, for CT neck examination were 993.3 ± 539.5 (267.3–2441.7). The mean and range of volume CT dose per slice (CTDIvol (mGy)) were 1.5 ± 3.9 (3.91–22.55). The overall effective dose (mSv) per procedure is ranged from 1.3 to 11.7 with a mean value 2.8 mSv. Patients' CT neck procedures have been repeated the procedure up to 7 times during the treatment course. The risk of malignancy is 1x10-6 CT procedure. The study showed that patients received wide discrepancies in patients' doses up to 9 times. Optimization of image acquisition protocol and scan length is necessary to reduce the unnecessary risk. •The effective and organ equivalent doses during neck CT procedure were studied.•Lens of the eye, salivary gland and thyroid gland received a high radiation dose.•The overall effective dose (mSv) per procedure is ranged from 1.3 to 11.7•Patients' CT neck procedures have been repeated the procedure up to 7 times during the treatment course.

    F. Moradi, M.A. Olatunji, S.F. Abdul Sani, N.M. Ung, F. Forouzeshfar, M.U. Khandaker, D.A. Bradley (2019)Composition and thickness dependence of TLD relative dose sensitivity: A Monte Carlo study, In: Radiation measurements129 Elsevier Ltd

    Absorbed dose sensitivity (SAD) of a dosimeter results from absorbed dose energy dependence (f) and intrinsic energy dependence (kbq) both influenced by compositional and dimensional details. Within attenuating media the SAD is also affected by the depth at which measurements are made as beam quality varies. Monte Carlo simulations allow for studying absorbed dose, importantly providing an effective means by which correction terms for detector response (frel) can be determined. Among the wide range of TLD materials that are available, most generally in particular geometries and size, the commercial products TLD-100 and TLD-100H are perhaps the types most commonly favoured by users. Comprising lithium fluoride (Li natural) co-doped with the activators Mg and Ti or Mg, Cu and P and compressed in a teflon binder to form thicknesses of from 1 mm to a few mm, these have been investigated in previous studies. For some common TLD materials available in small thickness, from 0.125 mm up to 1.000 mm, present study seeks to calculate and compare frel values obtained at different measurement depths in water relative to a reference depth. In simulating a reference radiation field, use has been made of the MCNPX code, calculation providing the correction factors at various depths in a water phantom. Results show that at sub-millimeter dimensions, the effect of detector thickness is more pronounced than the effective atomic number, Zeff, and density of the TLDs. Smaller thickness and higher Zeff TLDs need significant correction factors, with their deviation from unity increasing with the depth up to 15 cm; frel values in the range of 0.96–1.01 were obtained in this study. Perturbation resulting from the presence of the dosimeter was also evaluated in terms of dosimeter size and material composition. Although dosimeter size, density and Zeff are well-known parameters, all important in assessing the amount of perturbation, it has been shown herein that the effect of density is more pronounced than Zeff. For the particular TLDs it is also shown that 0.125 mm thick dosimeters produce a perturbation that might be considered negligible for radiation fields larger than a few centimeters. •MCNPX code was used to evaluate spectral changes with depth of a 6 MeV clinical photon beam.•Absorbed dose energy dependence and field perturbation of various small size TLDs were calculated.•LiF, SiO2 and CaF2 TLD materials with thicknesses of 0.125–1 mm were studied.•Results show that a larger correction is needed for higher density and Zeff and smaller TLD thicknesses.•The field perturbation caused by presence of a dosimeter is affected by its density more than Zeff.

    M. K. Muhamad Azim, A. Arifutzzaman, R. Saidur, M. U. Khandaker, D. A. Bradley (2022)Recent progress in emerging hybrid nanomaterials towards the energy storage and heat transfer applications: A review, In: Journal of molecular liquids360 Elsevier

    Hybrid nanomaterials, which is a combination of two or more nanoparticles have been extensively evaluated as a promising candidate for energy storage and heat transfer applications, benefitting from the rise of synergistic effects between them. The unique form of this emerging combination of nanomaterials not only offers the improved features of the integrated nanoparticles but gives us the opportunity to tailor their physicochemical properties simply by modifying their composition and morphology. Scientific findings have demonstrated that the dispersion of hybrid nanomaterials in the base fluids, known as -hybrid nanofluids gives us the alternative way to replace mono nanofluid and the conventional heat transfer fluids as it provides a much better heat transfer enhancement that is beneficial for advanced heat transfer devices. On the other hand, when hybrid nanomaterials were utilized for energy storage devices, it exhibits an outstanding electrochemical performance, providing a significant contribution to the specific capacitance which permits a new strategy to design new electrodes for advanced energy storage devices. In this article review, we summarised the recent advancements made on the emerging hybrid nanomaterials, comprising of the general overview of the emerging nanomaterials, the synthesis routes for hybrid nanomaterials and their acquired hybrid structures along with their practical applications as electrodes in electrochemical energy storage and as heat transfer fluids for advanced heat transfer devices. Finally, we have also outlined some challenging issues associated with hybrid nanomaterials that requires further attention for future research.(c) 2022 Elsevier B.V. All rights reserved.

    K. Aladeniyi, A.M. Arogunjo, A.J.S.C. Pereira, Mayeen Uddin Khandaker, D.A. Bradley, A. Sulieman (2021)Evaluation of radiometric standards of major building materials used in dwellings of South-Western Nigeria, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    Realizing the probable health risk via the exposures to gamma radiations caused by terrestrial radionuclides, concentrations of 40K, 226Ra(238U) and 232Th radionuclides in popularly used building materials were investigated by gamma-ray spectroscopy. A total of 173 samples representative of major building materials (both structural and decorative category) used for Nigerian dwellings were studied. The mean (GM) activity concentrations of the 40K, 226Ra(238U) and 232Th in the surveyed samples are 286 ± 3, 29 ± 3 and 26 ± 5 Bqkg-1 respectively. Associated radiation hazard parameters were estimated and the results are compared with the available literature data and the prescribed limits set by international regulatory bodies to identify the radiometric standards of the studied materials. This study shows that the use of tile and granite should be minimized for building constructions. Moreover, perpetual monitoring of radiation level in clay- and mud-bricks should be intensified to avoid unwanted radiation exposure to dwellers. Overall, measured data may serve as an important component of the database to set up guidelines required for controlling building materials usage in dwelling purposes. •The presence of terrestrial radionuclides in a range of building materials are determined.•Measured data show higher levels in mud-, clay-, cement-blocks and Tiles samples.•The mixing of glaze materials in the tiles may elevate the NORM level.•Calculated ELCR were observed to be higher than the world average value of 0.29 × 10-3.

    Ammar Alhasan, S.F. Abdul Sani, Hairul Anuar Tajuddin, Tammar Hussein Ali, Shameer Hisham, N.M. Ung, Nurul Amniyyah Azhar, Nur Akmarina BM Said, Amira Hajirah Abd Jamil, D.A. Bradley (2023)Synthesis of I@MPA-Mn:ZnSe as an efficient contrast agent for CT/fluorescence bi-modal imaging application, In: Radiation physics and chemistry (Oxford, England : 1993)209 Elsevier Ltd

    Bi-modal imaging contrast agent has attracted considerable attention in medical physics research field via quantum dots (QDs) fabrications. Doped quantum dots are playing an important role in seeking alternatives to conventional heavy metal-containing particles for medical applications. In order to improve imaging diagnosis, herein we report the design and synthesis of I@MPA-Mn:ZnSe as an efficient contrast agent. The medium, mercaptopropionic acid (MPA) capped Mn:ZnSe QDs surface-conjugated with a commercial contrast agent (Iohexol), was synthesized in seeking to overcome the limitations of Iohexol, also towards advancing bi-modal imaging approaches. In this study, morphology, elemental, absorption and fluorescence analysis were investigated, followed by a preliminary study of CT contrast enhancement and cell viability. In comparison to Iohexol, the fluorescence of I@MPA-Mn:ZnSe is observed at 585 nm. The CT Hounsfield unit (HU) increases linearly with mass concentration, with a four-fold increment in HU over that of Iohexol, producing greater than 328 ΔHU at similar concentrations, confirming the CT contrast efficiency of I@MPA-Mn:ZnSe. Cytotoxicity studies have confirmed that the medium possesses good biocompatibility and low toxicity to cells (HepG2 and MDA-MB-321). Present results for CT enhancement and brightness of fluorescence of I@MPA-Mn:ZnSe point to its great potential as a bi-modal contrast medium for further diagnosis applications. •I@MPA-Mn:ZnSe as bi-modal contrast agent via quantum dots (QDs) fabrications.•CT Hounsfield unit (HU) of I@MPA-Mn:ZnSe increases linearly by four-fold over that of Iohexol.•Good biocompatibility and low toxicity of I@MPA-Mn:ZnSe to cells (HepG2 and MDA-MB-321).

    D. A. Bradley, M. Iqbal Saripan (2021)Preface, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier
    F. Moradi, N. M. Ung, G. A. Mahdiraji, M. U. Khandaker, M. H. See, N. A. Taib, D. A. Bradley (2019)Evaluation of Ge-doped silica fibre TLDs for in vivo dosimetry during intraoperative radiotherapy, In: Physics in medicine & biology64(8)pp. 08-NT04 Iop Publishing Ltd

    Ge-doped silica fibre (GDSF) thermoluminescence dosimeters (TLD) are non-hygroscopic spatially high-resolution radiation sensors with demonstrated potential for radiotherapy dosimetry applications. The INTRABEAM (R) system with spherical applicators, one of a number of recent electronic brachytherapy sources designed for intraoperative radiotherapy (IORT), presents a representative challenging dosimetry situation, with a low keV photon beam and a desired rapid dose-rate fall-off close-up to the applicator surface. In this study, using the INTRABEAM (R) system, investigations were made into the potential application of GDSF TLDs for in vivo IORT dosimetry. The GDSFs were calibrated over the respective dose- and depth-range 1 to 20 Gy and 3 to 45 mm from the x-ray probe. The effect of different sizes of spherical applicator on TL response of the fibres was also investigated. The results show the GDSF TLDs to be applicable for IORT dose assessment, with the important incorporated correction for beam quality effects using different spherical applicator sizes. The total uncertainty in use of this type of GDSF for dosimetry has been found to range between 9.5% to 12.4%. Subsequent in vivo measurement of skin dose for three breast patients undergoing IORT were performed, the measured doses being below the tolerance level for acute radiation toxicity.

    K. Alzimami, A. Sulieman, Hiba Omer, Layal K. Jambi, A. Alfuraih, N. Al Hossain, E. Babikir, M. Alkhorayef, Mayeen Uddin Khandaker, D.A. Bradley (2021)Evaluation of pediatric radiation doses in computed tomography procedures in the Kingdom of Saudi Arabia, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier Ltd

    Computed tomography (CT) frequency is approximately 11% of medical radiological procedures. Nevertheless, CT examinations contribute up to 70% collective doses. CT procedures carried out in pediatric patients represent 33% of CT procedures. This study aimed to assess pediatric doses during chest and abdomen procedures and estimated the projected radiogenic risk. In total, 83 pediatric were divided into four groups, according to their age (years). The patients were ≤six months, six months - ≤3 years, 4 - ≤ 6 years and, 7 - ≤ 15 years. The mean and range of DLP ( and CTDIvol (mGy) for pediatric CT chest were 42 (33–52) and 2 (1.9–2.2), respectively. The mean and range of DLP ( and CTDIvol (mGy) for pediatric CT abdomen pelvic region were 116 (105–129) and 3.8 (3.7–3.9), in that order. Even though pediatric' radiation doses are below the published diagnostic reference levels (DRL), additional dose reduction is required and achievable if the imaging protocol is adjusted according to the child size. •Pediatric doses during CT chest and abdomen procedures were assessed.•The variation in patients' doses was due to the scan length and child weight.•The Patients' radiation doses were lower than available published values.•The study has revealed an indispensable need for justified referring criteria.•Establishing an imaging protocol based on a pediatric subgroup is recommended.

    S.S. Ismail, S.F. Abdul Sani, M.U. Khandaker, N. Tamchek, C.M. Ridzuan, Julia A. Karim, K.S. Almugren, F.H. Alkallas, D.A. Bradley (2021)Effect of neutron exposure on structural and optical properties of tailor-made Gd-Doped SiO2 glass, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier Ltd

    The effect of neutron irradiation is investigated in respect of five different Gd dopant concentrations of silica (SiO2) glass; 1–10 mol% via sol-gel route fabrication. Using Raman spectroscopy and X-ray diffraction (XRD), characterization was made of the defects that give rise to the luminescence signal. The approach allows the Si–O–Si coordination to be identified and studied. The fabrication process as well as irradiation have been found to produce defects which influence the luminescence response of the material. The Raman spectra from Gd-doped SiO2 glass neutron irradiated to doses from 2 to 10 Gy show five prominent peaks (at 300, 430, 680, 820, 1050 cm−1) with the presence of Gd-O-Gd seen at 300 cm−1. The Miller index (211) crystal plane observed from XRD allowed calculation of the atomic spacing, lattice constant and degree of structural order of the irradiated samples. The results show that from fabrication of silica of different Gd dopant concentration and the effect of neutron irradiation these lead to a number of desirable characteristics for use of the medium as a dosimetric system for neutron radiation physics applications. •Sol gel glass doped with Gd at 1–10 mol% concentration irradiated to neutron source.•Change in lattice structure and defect upon exposure to neutron radiation.•Gd-O-Gd bond is found to be at 300 cm−1 Raman band.•Si–O–Si bond are found to be at 430, 680, 820 and 1050 cm−1 Raman band.•The doping support an increase in amorphous.

    Mahfuza Begum, A K M Mizanur Rahman, H A Abdul-Rashid, Z Yusoff, Siti Nurasiah Mat Nawi, Mayeen Uddin Khandaker, D A Bradley (2021)Photonic crystal fibre as a potential medium for radiotherapy dosimetry, In: Applied radiation and isotopes174pp. 109771-109771

    Present study concerns the key thermoluminescence (TL) properties of photonic crystal fibres (PCFs), seeking development of alternatively structured TL materials that are able to offer a advantages over existing passive dosimeters. In terms of their internal structure and light guiding properties the PCFs, collapsed and structured, differ significantly from that of conventional optical fibres. To investigate the dosimetric parameters of the PCFs use was made of a linear accelerator producing a 6 MV photon beam, delivering doses ranging from 0.5 Gy to 8 Gy. The parameters studied included TL response, linearity index, glow curves, relative sensitivity and TL signal fading, the results being compared against those obtained using TLD-100 chips. At 4 Gy photon dose the Ge-doped collapsed PCFs were found to provide a response 27 × that of structured PCF, also giving a TL yield similar to that of standard TLD-100 chips. Over post-irradiation periods of 15 and 30 days collapsed PCF TL signal fading were 8% and 17% respectively, with corresponding values of 37% and 64% for the structured PCF. Trapping parameters including the order of kinetics (b), activation energy (E) and frequency factor (s ) were assessed with Chen's peak shape method. Lifetime of trapping centre was found to be (2.36 E+03) s and (9.03 E +01) s regarding the collapsed and structured PCF respectively with 6 Gy of photon beam. For the Ge-doped collapsed PCF, the high TL yield, sensitivity and low fading provide the basis of a highly promising system of TLD for radiotherapy applications.

    Halmat Jalal Hassan, Suhairul Hashim, Noor Zati Hani Abu Hanifah, Sib Krishna Ghoshal, Mohamad Syazwan Mohd Sanusi, Fariza Hanim Binti Suhailin, Muhammad Fahmi Rizal Abdul Hadi, Rozman Mohd Tahar, David Andrew Bradley (2021)Naturally Occurring Radioactive Materials in Bracelets and Necklaces: Radiological Risk Evaluation, In: International journal of environmental research and public health18(21) MDPI

    A particular category of jewelry is one involving bracelets and necklaces that are deliberately made to contain naturally occurring radioactive material (NORM)—purveyors making unsubstantiated claims for health benefits from the release of negative ions. Conversely, within the bounds of the linear no-threshold model, long-term use presents a radiological risk to wearers. Evaluation is conducted herein of the radiological risk arising from wearing these products and gamma-ray spectrometry is used to determine the radioactivity levels and annual effective dose of 15 commercially available bracelets (samples B1 to B15) and five necklaces (samples N16 to N20). Various use scenarios are considered; a Geant4 Monte Carlo (Geant4 MC) simulation is also performed to validate the experimental results. The dose conversion coefficient for external radiation and skin equivalent doses were also evaluated. Among the necklaces, sample N16 showed the greatest levels of radioactivity, at 246 ± 35, 1682 ± 118, and 221 ± 40 Bq, for 238 U, 232 Th, and 40 K, respectively. For the bracelets, for 238 U and 232 Th, sample B15 displayed the greatest level of radioactivity, at 146 ± 21 and 980 ± 71 Bq, respectively. N16 offered the greatest percentage concentrations of U and Th, with means of 0.073 ± 0.0002% and 1.51 ± 0.0015%, respectively, giving rise to an estimated annual effective dose exposure of 1.22 mSv, substantially in excess of the ICRP recommended limit of 1 mSv/year.

    R.S. Omar, S. Hashim, D.A. Bradley, M.K.A. Karim, N.D. Shariff (2022)Anthropomorphic phantom organ dose assessment using optically stimulated luminescence dosimeters unified in multi-detector computed tomography, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    This organ dose profile investigation is based on a technology that allows for the acquisition of densely sampled dose data, obtained using modified nanoDot™ OSLDs and a typical anthropomorphic Alderson Radiation Therapy phantom (ARTM 1092 model). The CT scan parameters were based on adult chest-abdomen and head region CT procedures, which were performed using a Siemens Somatom Definition AS+ at Hospital Sultanah Aminah in Johor. In studying the scanned region, the tube voltage and exposure duration values were considerably altered, with modulation approaches significantly altering the dosage distribution. In the head-neck procedure, the average absorbed dose per slice for the brain and thyroid was 3.469–33.645 mGy and 3.372–34.528 mGy, respectively. The distribution of chest-abdomen region organ dose mapping explains that the lungs received the highest organ dose, receiving a dose of 20.795 mGy from protocol P4, a setting of 140 kV tube voltage in the CT chest-abdomen protocol. The organ dosage levels in this investigation varied from 2.277 to 20.794 mGy, depending on tube voltage, tube current, and exposure period, as well as the organ composition, location, and surrounding anatomic structures. The average absorbed dosage in the lungs per slice varied from 3.439 to 20.794 mGy. The most significant coefficient of variation (CoV) for dosage samples of the lungs inside separate slices was 13%. The radiation dose patterns are consistent with similar tests and modalities, with variations dependent on tube voltage, exposure period, tube current, slice collimation, and pitch factor. The LED and CAL measured data (Mean ± SD) were determined to be an average of 4657 ± 563 and 1677 ± 31 counts, respectively. The supplied data is evidence of the microStar reader's superior performance. •We utilized nanodot OSL to measure absorbed dose from routine CT examination.•Nanodot OSL dosimeter were calibrated and shows good linearity and stability.•CT acquisition parameter significantly influence the dose distribution.•Lung and thyroid in CT chest-abdominal examination record highest organ absorbed dose.

    S.N. Mat Nawi, Mayeen Uddin Khandaker, S.F. Abdul Sani, N.M. Ung, S.E. Lam, K.S. Al-mugren, D.A. Bradley (2021)The potential of polymer pencil-lead graphite for clinical electron beam dosimetry, In: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment1010 Elsevier B.V

    The dosimetric capabilities of tissue equivalent rod-shaped polymer pencil lead graphite (PPLG) has been investigated using an Elekta HD Linac, evaluated for electrons from 6 to 15 MeV and doses in the range 0.5 Gy up to 20 Gy. These encompass the major irradiation value ranges used in electron radiation therapy procedures. Parameters concerning thermoluminescence (TL) dosimetry have been investigated, including reproducibility, TL glow curve, the linearity of dose response, sensitivity, energy response and fading. The smaller diameter PPLG samples (0.3 mm) offer excellent dosimetric characteristics, superior to that of the 0.5 mm, 0.7 mm, and 0.9 mm diameter rods. This study confirms that low-cost Pencil Lead-Graphite (PLG) dosimeters provide energy independent dose sensitive linear response over a wide dose range. The small physical size offers unchallenged point detector spatial resolution, also enjoying minimal rates of fading and insensitivity to room lighting. As such, PPLG offers a viable alternative to current commercial dosimeters, well suited to applications in radiotherapy.

    L. Isolan, M. Sumini, F. Teodori, D. Bradley, S. Jafari, F. Mariotti, F. Buontempo (2019)Dosimetric analysis and experimental setup design for in-vivo irradiation with a Plasma Focus device, In: Radiation physics and chemistry (Oxford, England : 1993)155pp. 17-21 Elsevier Ltd

    Looking at possible clinical applications of the Plasma Focus (PF) technology as medium-low energy extremely fast radiation source, aiming at the treatment of skin cancer pathologies, in vivo experiments on mice are a due step. To properly design the experiments, a dosimetric analysis on a PMMA mouse phantom has been devised and carried out. The dose delivered to the phantom has been evaluated in experiments using Gafchromic films, standard TLD chips and TL glass beads to be able to optimally reconstruct the radiation field produced by the PF at various depths in the phantom. The whole setup has also been analysed with a Monte Carlo model using the MCNP6 code to produce a correlation between the results obtained from the various dosimetric technologies. •A Plasma Focus device is analysed as X-ray source for medical applications.•The dosimetry to evaluate the possibility of in-vivo experiments has been setup.•A comparison between experimental data and MC simulations with the MCNP6 code has been carried out.

    Mohamed M. Abuzaid, Wiam Elshami, H. O. Tekin, Abdelmoneim Sulieman, D. A. Bradley (2021)COMPARISON OF RADIATION DOSE AND IMAGE QUALITY IN HEAD CT SCANS AMONG MULTIDETECTOR CT SCANNERS, In: Radiation protection dosimetry196(1-2)pp. 10-16 Oxford Univ Press

    The present study compares three different multidetector CT (MDCT) scanners for routine brain imaging in terms of image quality and radiation doses. The volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose (E) were calculated. Subjective image assessment was obtained based on a scale ranging from 1 (unacceptable) to 5 (optimum). All images scored 3.5 or over, with the 160-slice MDCT images being favoured. For the 4-, 16- and 160-slice MDCT scanners, the respective median values for CTDIvol were 57 mGy, 41 mGy, and 28 mGy; DLP values were 901, 680, and 551; and effective doses were 2 mSv, 1.5 mSv, and 1 mSv, respectively. Compared to the 160-slice MDCT, the dose values for the 4- and 16-slice units were significantly greater. In practice, the CT modality used must be carefully selected to avoid elevated radiation doses and maintain image quality.

    Tareq Alrefae, Tiruvachi N. Nageswaran, Nasser S. Demir, Mayeen Uddin Khandaker, David A. Bradley, Mohammed Alkhorayef, Khalid S. Alzimami (2018)Committed effective dose to the Kuwaiti population via the dietary intake of red meat, In: Results in physics10pp. 827-831 Elsevier

    Meat is a major component of the daily diet of the Kuwait population. Realizing the negative consequences of the presence of radioactive materials in foodstuffs, various types of meat (fresh and processed lamb and beef) on sale in Kuwaiti markets have been assessed. The interest is in seeking to obtain a measure of the potential radiological impact to human health that results from their consumption. High purity germanium.-ray spectrometry of the meat has revealed low activities of Ra-226 and Ra-228, key indicators of the respective U-238 and Th-232 natural decay series. While elevated activities of K-40 were observed in a number of the fresh meat samples, evidence of the anthropogenic radionuclide Cs-137 was found in one sample only. A statistically significant difference was found between the mean value of activity concentration of K-40 in fresh and processed beef samples. The total potassium concentration in the meat samples was calculated from observation of K-40 activity, values ranging between 2.6 and 17.2 g kg(-1). The annual effective dose resulting from meat consumption for a typical adult in Kuwait has been estimated to be 217 mu Sv y(-1), somewhat less than the 290 mu Sv y(-1) assessed by UNSCEAR (2008) to prevail more globally. Findings from this research are intended to underline the importance of periodic monitoring of foodstuffs in efforts towards mitigating radiological risk.

    F. Moradi, G.A. Mahdiraji, M.U. Khandaker, N.M. Ung, F.R. Mahamd Adikan, I. Khellaf, D.A. Bradley (2018)Investigation on various types of silica fibre as thermoluminescent sensors for ultra-high dose radiation dosimetry, In: Sensors and actuators. A. Physical273pp. 197-205 Elsevier B.V

    •13 types silica fibres are examined as potential sensor material for high dose dosimetry.•Thermoluminescence response of fibres are obtained at dose range of 0.1–100 kGy.•Various fibre types show different dose level of saturation starting from 5 kGy.•Borosilicate fibre demonstrates best performance with linear response till 100 kGy.•Further dosimetric characterisation of Borosilicate fibre are presented. With high-dose applications lacking the benefit of an economic yet versatile dosimeter that provides for a wide dynamic dose range, ongoing research is seeking to introduce suitable thermoluminescent (TL) material for such needs. Acknowledging the high potential of silica fibres, as developed by members of this group over the past few years, in present work evaluation has been made of 13 types of fibre, differing in dopant, dopant concentration and diameter including P−, Al−, Er−, Ge− and Al-Tm-doped fibres, ultra-high numerical aperture and borosilicate fibre, and two non-doped fibres, quartz and suprasil F300. Evaluation is made in terms of TL response to photon and electron irradiations with the objective of determining a TL material that can offer sensitive yet extended dose capability, saturating only above the few tens of kGy range. The various silica fibres that have been investigated were found to show saturation levels from 5 kGy for Ge-doped fibre (4 mol %) to 80 kGy for 2 mol % Al−doped silica fibre. Borosilicate fibres demonstrated the greatest potential for high dose dosimetry, maintaining a highly-linear response, any tendency towards saturation only being indicated to beyond receipt of doses of 100 kGy. For this fibre type detailed TL characterizations were conducted, including glow curve analysis, reproducibility and fading tests. The results suggest borosilicate fibre to be suitable for high dose TL dosimetry, providing sufficient sensitivity and appropriate dosimetric characteristics.

    M. A. A. Husain, S. Hashim, D. Bradley, M. H. Rabir, N. Zakaria, M. R. M. Zin (2019)Investigation on Neutron Flux Effect onto Irradiated Fuel Burn-up Stored in the Reactor TRIGA PUSPATI, In: Atom Indonesia45(1)pp. 59-65 Natl Atomic Energy Agency Indonesia

    An investigation on the out-core neutron flux in the Reactor TRIGA PUSPATI is carried out in this work to determine whether the thermal and/or fast neutron from the core would cause burn-up of the irradiated fuel stored in the same vicinity of the reactor core. The storage rack is positioned at 1 m from the central thimble. MCNPX code is used to calculate the fast and thermal neutron flux at 750 kW reactor power using 10 cm x 10 cm x 10 cm mesh while MATLAB model on 20 cm x 20 cm mesh model is used to plot the axial and radial distribution of the neutron flux density. The results show that the thermal neutrons occurred at energy lower than 1 x 10(-6) MeV and traveled to a maximum distance of 78 cm. The greatest flux for thermal and fast neutrons is 1 x 10(13) and 5 x 10(13) respectively. The fission-rate of the fuel in the core is determined to be 3.18 x 10(14) particle/s compared to 1.51 x 10(7) particle/s of the irradiated fuel in the storage rack. The burn-up of the fuel in the storage rack is in the order of micrograms and therefore is negligible. It is concluded that neutron flux from the core would not impart burn up effect onto the irradiated fuel stored at the storage rack in the reactor pool. (C) 2019 Atom Indonesia. All rights reserved

    N.N.M. Rais, D.A. Bradley, A. Hashim, N.M. Isa, N.D. Osman, I. Ismail, H.A. Hassan, N.M. Noor (2021)Fabricated germanium-doped optical fibres for computed tomography dosimetry: Glow curve characteristics, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier Ltd

    Fabricated germanium (Ge)-doped optical fibre glow curve characteristics are investigated with respect to computed tomography (CT) dosimetry. 2.3 mol% and 6 mol% Ge-dopant concentration preforms have been used to produce flat and cylindrical fibres (FF and CF) of various size and diameter. The fibres are irradiated to doses of 20, 30 and 40 mGy for each of the beam qualities RQT 8 (100 kV), RQT 9 (120 kV) and RQT 10 (150 kV). The thermoluminescence (TL) kinematic parameters studied are maximum temperature (Tmax), activation energy (Ea) and peak integral (PI). The glow curve formations are reconstructed from the Windows®–based radiation evaluation and management system (WinREMS), deconvoluted using glow curve deconvolution (CGCD) analysis software. The structures of the glow curves are broad single or double-peaked, occurring at relatively high glow peak temperatures, TL response increases with radiation dose and peak height decreases with increasing energy, showing clear photoelectric dependence. The deconvoluted glow curves for all fibres are seen to consist of five individual glow peaks, P1 to P5, P1 being dominant in all cases other than for 6 mol% Ge-FF for which P3 is dominant due to the formation of a double-peaked glow curve. Tmax increases from P1 to P5 for all fibres, throughout the energy range used. P1 and P3 (6 mol% Ge-FF) have the lowest Ea, while P4 shows the greatest Ea for all fibres. The results indicate that electrons in P1 and P3 (6 mol% Ge-FF) are occupied at low energy traps while for P4, the electrons are trapped at a deeper energy level. The lowest PI value, indicative of the least number of electrons, is shown to be that of the deeper trap P4 for all energies investigated. This study provides support for the use of 6 mol% and 2.3 mol% preform fibres for CT dosimetry, each with similar kinetic parameters. •Glowcurve characteristics of fabricated 2.3 mol% and 6 mol% Ge-doped optical fibres investigated for CT dosimetry.•Thermoluminescence kinematic parameters studied are: maximum temperature, activation energy and peak integral.•Majority of low energy electron traps are occupied using RQT beam quality radiation.

    F. Moradi, M. Jalili, Kh Rezaee Ebrahim Saraee, M.U. Khandaker, D.A. Bradley (2022)Geant4 track structure simulation of electron beam interaction with a gold nanoparticle, In: Radiation physics and chemistry (Oxford, England : 1993)200
    Chetan Pandit, Arpita Roy, Suresh Ghotekar, Ameer Khusro, Mohammad Nazmul Islam, Talha Bin Emran, Siok Ee Lam, Mayeen Uddin khandaker, David Andrew Bradley (2022)Biological agents for synthesis of nanoparticles and their applications, In: Journal of King Saud University. Science34(3) Elsevier

    In terms of cost-efficiency, biocompatibility, environmental friendliness, and scalability, green nanoparticle (NP) synthesis is a novel field of nanotechnology that outperforms both physical and chemical approaches. Plants, bacteria, fungi, and algae have lately been used to produce metals and metal oxide nanoparticles as an alternate method. The development of alternative strategies to restrict the growth of hazardous bacteria, as well as the building of resistance by germs to various antibiotics, led to the introduction of nanoparticles as novel antimicrobial agents. Metal oxides have been found to form oxide monolayer structures for drug delivery when they react with a transporter's surface. Metal oxide nanoparticles have emerged as biomedical materials in recent years, with applications in immunotherapy, tissue treatment, diagnostics, regenerative medicine, wound healing, dentistry, and biosensing platforms. Biotoxicology and its antimicrobial, antifungal, and antiviral characteristics were hotly contested. Metal oxide nanoparticles have tremendous applicability and commercial value, as evidenced by important discoveries in the realm of nanobiomedicine in terms of locations and amounts. This paper describes the production of nanometal oxides from various green materials, as well as their applications.(c) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY license (

    Niloofar Azadegan, Mehdi Hassanpour, Mayeen Uddin Khandaker, Mohammad Rashed Iqbal Faruque, K.S. Al-mugren, D.A. Bradley (2021)Calculation of secondary radiation absorbed doses due to the proton therapy on breast cancer using MCNPX code, In: Radiation physics and chemistry (Oxford, England : 1993)183 Elsevier Ltd

    Secondary radiation damage caused by proton radiation therapy can affect other tissues and result in unwanted doses. Therefore, it is necessary to calculate the secondary radiation doses (from scattering processes) for radiation protection issues. In this study, we simulated a proton beam in a 10 cm distance (from source-to-surface distance) was used to irradiate a hypothetical breast tumor at the MIRD phantom under conditions of variable beam radius and energy. Thereafter, absorbed doses to the tumor and scattering radiation doses to the heart, lung, liver, stomach, and spleen were calculated. The results showed that the maximum scattered neutron dose-to-organs close to the breast, such as the heart, lung, liver, stomach and spleen, with 70 MeV proton energy and beam radius of 1 cm are negligible. Finally, the spread-out Bragg peak was obtained using an appropriate weighted combination of beams of different energies which can be replaced as a suitable method instead of modulator wheel design for applying in MCNPX code input program. The evaluated indices in this study are the absorbed tumor doses for single particle and the scattered doses due neutrons and photons. The results showed that the majority of scattered radiation is neutrons. Scattered particle spectral powers for neutrons and photons were also plotted. It was observed that in the photon spectra, the maximum scattered radiation occurs with the beam of 1 cm radius and 70 MeV energy, while the neutron spectra show that scattered radiation is predominantly at low energy. Finally, a spread-out Bragg peak appropriate for a hypothetical tumor with 1.77 cm width was obtained, and the absorbed doses and scattered doses were calculated. •Secondary radiation from proton radiation therapy may result in unwanted doses to normal tissues.•Scattering radiation doses on the heart, lung, liver, stomach, and spleen were calculated by MCNPX.•The spread-out Bragg peak was obtained using the energy change method.•The maximum photon scattering dose occurs in the beam with 1 cm radius and 70 MeV energy,•The neutrons spectra in low energy shows the highest scattered radiation dose.

    W. Ali, A. Sulieman, Nissren Tamam, N. Boshara, A. Aldhebaib, M. Alkhorayef, Mayeen Uddin Khandaker, D.A. Bradley (2021)Estimation of patients organ doses and staff exposure during bone scan examination, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier Ltd

    Radiopharmaceuticals are utilized in diagnostic nuclear medicine (NM) for a wide range of disorders. The purposes of the work are to assess patient organ doses in bone scan procedure with 99 m Tc-Methyl diphosphonate (MDP) and quantify the NM technologist exposure during bone scan procedure. Staff radiation exposure was determined using thermo-luminescent dosimeters (TLDs, Type LiF: Mg, Cu, P (GR200A)) were placed at the dominant hand. The TLD was calibrated to estimate the personal equivalent dose Hp (10) and Hp (0.07). The mean and range of the annual personal dose equivalent (Hp (10) and Hp (0.07) mSv) were 7.6 (3.2–9.1) and 30 (17.2–44), respectively. The patients' bladder retains an insignificant amount of the administered activity. Vast differences in patients’ and occupational doses were detected. Increasing staff awareness about radiation safety is recommended to enhance radiation protection and education unnecessary radiation doses. The personal doses equivalent are within the acceptable annual determined limits. •NM Technologist personal equivalent dose Hp (10) and Hp (0.07) were quantified.•Vast differences in patients' and occupational doses were detected.•The patients' bladder retains an insignificant amount of the administered activity.•The personal doses equivalent are within the acceptable annual determined limits.

    D.A. Bradley, Siti Nurasiah Mat Nawi, S.F Abdul Sani, Mayeen Uddin Khandaker, K.S. Almugren (2022)Characterisation of graphite-based material for dosimetry in the mammographic energy range, In: Radiation physics and chemistry (Oxford, England : 1993)201
    D A Bradley, H T Zubair, A Oresegun, G T Louay, Alawiah Ariffin, Mayeen Uddin Khandaker, Khalid S Alzimami, H A Abdul-Rashid (2018)Radioluminescence sensing of radiology exposures using P-doped silica optical fibres, In: Applied radiation and isotopes141pp. 176-181

    In previous work we investigated the real-time radioluminescence (RL) yield of Ge-doped silica fibres and Al O nanodot media, sensing electron- and x-ray energies and intensities at values familiarly obtained in external beam radiotherapy. The observation of an appreciable low-dose sensitivity has given rise to the realisation that there is strong potential for use of RL dosimetry in diagnostic radiology. Herein use has been made of P-doped silica optical fibre, 2 mm diameter, also including a 271 µm cylindrical doped core. With developing needs for versatile x-ray imaging dosimetry, preliminary investigations have been made covering the range of diagnostic x-ray tube potentials 30 kVp to 120 kVp, demonstrating linearity of RL with kVp as well as in terms of the current-time (mAs) product. RL yields also accord with the inverse-square law. Given typical radiographic-examination exposure durations from tens- to a few hundred milliseconds, particular value is found in the ability to record the influence of x-ray generator performance on the growth and decay of beam intensity, from initiation to termination.

    Fawzia E. M. Elbashir, Wassim Ksouri, Mohamed Hassan Eisa, Sitah Alanazi, Farouk Habbani, Abdelmoneim Sulieman, David A. Bradley, Ibrahim I. Suliman (2021)Comparison of Dosimetry Protocols for Electron Beam Radiotherapy Calibrations and Measurement Uncertainties, In: Life (Basel, Switzerland)12(1) Mdpi

    This paper presents guidelines for the calibration of radiation beams that were issued by the International Atomic Energy Agency (IAEA TRS 398), the American Association of Physicists in Medicine (AAPM TG 51) and the German task group (DIN 6800-2). These protocols are based on the use of an ionization chamber calibrated in terms of absorbed dose to water in a standard laboratory's reference quality beam, where the previous protocols were based on air kerma standards. This study aims to determine uncertainties in dosimetry for electron beam radiotherapy using internationally established high-energy radiotherapy beam calibration standards. Methods: D-w was determined in 6-, 12- and 18 MeV electron energies under reference conditions using three cylindrical and two plane-parallel ion chambers in concert with the IAEA TRS 398, AAPM TG 51 and DIN 6800-2 absorbed dose protocols. From mean measured D-w values, the ratio TRS 398/TG 51 was found to vary between 0.988 and 1.004, while for the counterpart TRS 398/DIN 6800-2 and TG 51/DIN 6800-2, the variation ranges were 0.991-1.003 and 0.997-1.005, respectively. For the cylindrical chambers, the relative combined uncertainty (k = 1) in absorbed dose measurements was 1.44%, while for the plane-parallel chambers, it ranged from 1.53 to 1.88%. Conclusions: A high degree of consistency was demonstrated among the three protocols. It is suggested that in the use of the presently determined dose conversion factors across the three protocols, dose intercomparisons can be facilitated between radiotherapy centres.

    Meshari Alnaaimi, Abdelmoneim Sulieman, Nissren Tamam, Mohammed Alkhorayef, Musa Alduaij, Talal Mohammedzein, Othman Alomair, Y. Alashban, H. Salah, Amr A. Abd-Elghany, Hiba Omer, D. A. Bradley (2021)Estimation of patient effective doses in PET/CT-F-18-Sodium Fluoride examinations, In: Applied radiation and isotopes178 Elsevier

    The positron emitters (F-18-Sodium Fluoride (NaF)) and X-rays used in Positron emission tomography (PET) combined with computed tomography (PET/CT) imaging have a high radiation dose, which results in a high patient dose. The present research intends to determine the radiation dose and risks associated with PET/CT-18F-Sodium fluoride examinations in patients. The 18F-NaF PET/CT was used to investigate the doses of 86 patients. Patient exposure parameters and ImPACT software were used to calculate mean effective doses. The administered activity of 185 MBq (5.0 mCi) per procedure has a mean and range based on the patient's BMI (BMI). The range of patient effective doses per procedure was found to be 4-10 mSv, with a radiation risk of 1 x 10(-5) per procedure. Patient doses are determined by the patient's size, scanner type, imaging protocol, and reconstruction method. For further dose reduction, proper justification and radiation dose optimization is required.

    Edwin H. Uguru, Siti F. Abdul Sani, Mayeen U. Khandaker, Mohamad H. Rabir, Julia A. Karim, Daniel U. Onah, David A. Bradley (2021)Burn-up calculation of the neutronic and safety parameters of thorium-uranium mixed oxide fuel cycle in a Westinghouse small modular reactor, In: International journal of energy research45(8)pp. 12013-12028 Wiley

    Thorium fuel is presently a globally known future nuclear fuel alternative, having good neutronic, physical and chemical properties in addition to its spent nuclear fuel characteristic proliferation resistance. This research focused on the neutronic and safety parameters of thorium-uranium mixed oxide fuel cycle, utilising three fissile enrichment zones, a departure from the conventional single enrichment. The aim was to determine the range of three fissile zones adequate for thorium-uranium fuel cycle; investigating the performance efficiency of the fuel neutronic and inherent safety parameters in response to temperature differentials, which determines the viability of the fuel and core composition. Use was made of the MCNPX 2.7 code integrated with the CINDER90 fuel depletion code for steady-state and burn-up calculations. The k(eff), moderator temperature coefficient (MTC) and fuel temperature coefficient (FTC) of reactivity are affected by the range of fissile enrichment and fuel temperature which decreased with their respective increases. The MTC for all the moderator temperatures was within 0 to -40 pcm/K design value for UO2 fuel. Similarly, the FTC was within -3.5 to -1 pcm/K design value for all the fuel temperatures except after 2000 days, where a positive reactivity feedback was introduced. At similar to 86 MWd/kgHM single discharge burn-up, the result shows that similar to 90% of the initial fissile load was utilised for energy production at the normal reactor operating temperature (600 K) with a slight reduction at higher fuel temperature. The total fissile inventory ratio (FIR), U-233/kg-Th-232 and Pu-239/kg-U-238 inventory ratios were significantly large and increased with burn-up. It is remarkable that the FIR and the(233)U/kg-Th-232 inventory ratio did not reach conversion equilibrium until exit burn-up. The large percentage fuel utilisation supports the advantage of fissile enrichment zoning in a thermal nuclear reactor core, making the chosen novel three fissile enrichment zones for thorium-uranium fuel cycle reliable.

    Syed Taimoor Hussain Shah, Shahzad Ahmad Qureshi, Aziz ul Rehman, Syed Adil Hussain Shah, Arslan Amjad, Adil Aslam Mir, Amal Alqahtani, David A. Bradley, Mayeen Uddin Khandaker, Mohammad Rashed Iqbal Faruque, Muhammad Rafique (2021)A Novel Hybrid Learning System Using Modified Breaking Ties Algorithm and Multinomial Logistic Regression for Classification and Segmentation of Hyperspectral Images, In: Applied sciences11(16) Mdpi

    A new methodology, the hybrid learning system (HLS), based upon semi-supervised learning is proposed. HLS categorizes hyperspectral images into segmented regions with discriminative features using reduced training size. The technique utilizes the modified breaking ties (MBT) algorithm for active learning and unsupervised learning-based regressors, viz. multinomial logistic regression, for hyperspectral image categorization. The probabilities estimated by multinomial logistic regression for each sample helps towards improved segregation. The high dimensionality leads to a curse of dimensionality, which ultimately deteriorates the performance of remote sensing data classification, and the problem aggravates further if labeled training samples are limited. Many studies have tried to address the problem and have employed different methodologies for remote sensing data classification, such as kernelized methods, because of insensitiveness towards the utilization of large dataset information and active learning (AL) approaches (breaking ties as a representative) to choose only prominent samples for training data. The HLS methodology proposed in the current study is a combination of supervised and unsupervised training with generalized composite kernels generating posterior class probabilities for classification. In order to retrieve the best segmentation labels, we employed Markov random fields, which make use of prior labels from the output of the multinomial logistic regression. The comparison of HLS was carried out with known methodologies, using benchmark hyperspectral imaging (HI) datasets, namely "Indian Pines" and "Pavia University". Findings of this study show that the HLS yields the overall accuracy of {99.93% and 99.98%}(Indian Pines) and {99.14% and 99.42%}(Pavia University) for classification and segmentation, respectively.

    D Bradley, H Zubair, A Oresegun, G Louay, Hafiz Zin, N Ung, H Abdul-Rashid (2020)Time-resolved dose measurements of linear accelerator pulses using a fibre optic sensor: Applications and challenges, In: Radiation physics and chemistry (Oxford, England : 1993)167 Elsevier BV

    We present time-resolved radioluminescence (RL) measurements from P-doped silica optical fibre, demonstrating potential utility in pulsed source dosimetry. When subjected to 140 MU/min from a 6 MV photon linac source, a 220 µm-core fibre has produced a RL response of 720 ± 20 photon counts/pulse from a saw-tooth ~ 40 µs duration return-to-baseline waveform. Conversely, the Cerenkov stem signal within the radiation insensitive carrier fibre is observed to offer an amplitude amounting to a little less than 3% of that of the P-doped fibre, the sharply spiked response being of ~ 2 µs duration. On the basis of these results, the practical applications and the challenges in the establishment of an effective dosimetry system are discussed.

    Muhammad Zul Azri Muhammad Jamil, Faizal Mohamed, Nur Ratasha Alia Md Rosli, Irman Abdul Rahman, Mohd Idzat Idris, David Andrew Bradley, Marlida Md Nor, Siti Norsyafiqah Mohd Mustafa (2019)Effect of gamma irradiation on magnetic gadolinium oxide nanoparticles coated with chitosan (GdNPs-Cs) as contrast agent in magnetic resonance imaging, In: Radiation physics and chemistry (Oxford, England : 1993)165 Elsevier Ltd

    This study elucidates a gamma irradiation-reduction approach in producing small gadolinium nanoparticles specifically gadolinium oxide nanoparticles coated with chitosan (GdNPs-Cs). Chitosan was used as a natural stabilizer and coating agent, whereas gadolinium (III) chloride hexahydrate (GdCl3.6H2O) was used as a precursor. The gadolinium nanoparticle was synthesized via hydrothermal method prior to chitosan coating and gamma irradiation. The properties of the synthesized GdNPs-Cs were studied in term of molecular conformation, surface plasmon resonance and particle distribution via ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) characterization. Formation of two new UV–Vis peaks at 260 nm and 290 nm depicts the chemical changes of chitosan post gamma irradiation with visible surface plasmon resonance band correlating the reduction of nanoparticle size. Further analysis via TEM demonstrates that synthesized GdNPs-Cs had an average diameter size in the range of 30–45 nm post gamma irradiation, a reduction of size in comparison with control GdNPs-Cs of 120 nm particle size. Enhancement of T1 image obtained via magnetic resonance imaging (MRI) testing proved the capability of synthesized GdNPs-Cs as a contrast agent. Coherently, gamma irradiation-reduction method may be used in controlling the size of nanoparticle and potentially be applied in all major fields related to gadolinium nanoparticle. •Gadolinium nanoparticles (GdNPs-Cs) synthesized via gamma irradiation reduction method post hydrothermal synthesis.•Reduction of GdNPs-Cs particle size post gamma irradiation.•GdNPs-Cs enhances MRI image contrast.

    Abdullah Alsubaie, Eman Daar, L. Alsulaiti, Abdullah N. Al-Dabbous, Mariem Chamakh, Maisarah Jaafar, D A Bradley (2019)Elemental evaluation of urban road dirt in tropical, arid and maritime climates, In: Radiation physics and chemistry (Oxford, England : 1993)160pp. 48-55 Elsevier Ltd

    Interest is in vehicular trace elemental contributions to the environment, evaluated via analysis of road dirt. Results from SEM/EDX, ICP-MS and ICP-OES are compared for a wide range of elements. ICP-OES and ICPMS provide absolute quantification while SEM/EDX has provided weight % assessments. Roadside dirt has been sampled along busy campus roads of universities/research centres in Guildford, Riyadh, Kuwait City, Doha and Kuala Lumpur, satisfying interest in climatic influences as well as vehicle engine size (Gulf non-commercial vehicle engine capacities tending to be greater than those in the UK or Malaysia). A total of 100 street dust samples have been analyzed, elemental concentrations being reported for Mg, Al, Ti, Mn, Fe, Co, Zr, Mo, Ba, Tl, V, Rd, Pb, Cu, Zn, Ni, Cr, Cd, As, Hg and Au. For all five urban centres, Al, Fe, Mg, and Si values were found to be well above background while concentrations of Ti, Cr and Ba were lower than values reported by others. Au and Ag from catalytic convertors were found in some centres, albeit at very low concentrations and with particle sizes of the order of 0.5 µm. The various techniques offer complementary information on vehicular emission elemental concentrations in urban environments. •Metal element concentrations investigated in road dirt.•Concentration obtained in urban road dirt in tropical, arid and maritime climates.•Elevated levels Al, Fe, Mg and Si found, less so in tropical and maritime roads than in the arid zones.•The concentrations of Mg show greater elevations in a few of the Doha locations.

    Mahfuza Begurn, A. K. M. Mizanur Rahman, Mahbuba Begum, H. A. Abdul-Rashid, Z. Yusoff, D. A. Bradley (2018)Harnessing the thermoluminescence of Ge-doped silica flat-fibres for medical dosimetry, In: Sensors and actuators. A. Physical270pp. 170-176 Elsevier

    Study has been made of key thermoluminescence (TL) properties of Ge-doped silica flat-fibre, including TL glow curves, dose-rate dependency and reproducibility, the fibres being photon irradiated over the dose range 0.5- to 8 Gy, use being made of a medical linear accelerator (LINAC) operated at either 6- or 10 MV. Percentage depth doses (PDD) were also studied, comparison being made of fibre-measured PDD values against those obtained using an ionization chamber and standard TLD-100 and TLD-700 chips. The flat-fibre samples displayed a single prominent TL glow curve dosimetry peak at 249 degrees C, the structure of this remaining unchanged during repeat cycles of annealing and irradiation at different doses. For fixed dose, the TL responses of the samples also remained practically constant in use of five different dose rates in the range100 MU/min to 500 MU/min. The effective atomic number (Zeff) of the flat-fibre was calculated to be 13.37, greater than soft tissue (7.42) but within the range of values for human bone (11.6-13.8). Using the 6 MV photon beam, PDD studies yielded a dmax of 1.5 cm, consistent with the value attained using the ionization chamber and the standard TLD chips. At 2 cm depth, the optical fibre samples showed good agreement to within -4%, 1.3% and 4% respectively with measurements made in use of the ionization chamber, standard TLD-100 chips and TLD-700 chips. The study represents part of an overall plan towards development of silica fiber-based dosimeters for radiotherapy and diagnostic radiology applications. (C) 2018 Elsevier B.V. All rights reserved.

    S. Hashim, Y. Musa, S. K. Ghoshal, N. E. Ahmad, I. H. Hashim, M. Yusop, D. A. Bradley, A. B. A. Kadir (2018)Optically stimulated Al2O3:C luminescence dosimeters for teletherapy: H-p(10) performance evaluation, In: Applied radiation and isotopes135pp. 7-11 Elsevier

    The performance of optically stimulated luminescence dosimeters (OSLDs, Al2O3:C) was evaluated in terms of the operational quantity of H-P(10) in Co-60 external beam teletherapy unit. The reproducibility, signal depletion, and dose linearity of each dosimeter was investigated. For ten repeated readouts, each dosimeter exposed to 50 mSv was found to be reproducible below 1.9 +/- 3% from the mean value, indicating good reader stability. Meanwhile, an average signal reduction of 0.5% per readout was found. The dose response revealed a good linearity within the dose range of 5-50 mSv having nearly perfect regression line with R-2 equals 0.9992. The accuracy of the measured doses were evaluated in terms of operational quantity H-P(10), wherein the trumpet curve method was used respecting the 1990 International Commission on Radiological Protection (ICRP) standard. The accuracy of the overall measurements from all dosimeters was discerned to be within the trumpet curve and devoid of outlier. It is established that the achieved OSL Al2O3:C dosimeters are greatly reliable for equivalent dose assessment.

    D.A. Bradley, Z. Siti Rozaila, M.U. Khandaker, K.S. Almugren, Worawat Meevasana, S.F. Abdul Sani (2019)Raman spectroscopy and X-ray photo-spectroscopy analysis of graphite media irradiated at low doses, In: Applied radiation and isotopes147pp. 105-112 Elsevier Ltd

    We explore the utility of controlled low-doses (0.2–100 Gy) of photon irradiation as initiators of structural alteration in carbon-rich materials. To-date our work on carbon has focused on β-, x- and γ-irradiations and the monitoring of radiotherapeutic doses (from a few Gy up to some tens of Gy) on the basis of the thermoluminescence (TL) signal, also via Raman and X-ray photo-spectroscopy (XPS), providing analysis of the dose dependence of single-walled carbon nanotubes (SWCNT). The work has been extended herein to investigate possibilities for analysis of structural alterations in graphite-rich mixtures, use being made of two grades of graphite-rich pencil lead, 8H and 2B, both being in the form produced for mechanical pencils (propelling or clutch pencils). 2B has the greater graphite content (approaching 98 wt %), 8H being a mixture of C, O, Al and Si (with respective weight percentages 39.2, 38.2, 9.8 and 12.8). Working on media pre-annealed at 400 °C, both have subsequently been irradiated to penetrating photon-mediated doses. Raman spectroscopy analysis has been carried out using a 532 nm laser Raman spectrometer, while for samples irradiated to doses from 1 to 40 Gy, XPS spectra were acquired using Al Kα sources (hv ∼1400 eV); carbon KLL Auger peaks were acquired using 50 eV Pass Energy. At these relatively low doses, alterations in order-disorder are clearly observed, defect generation and internal annealing competing as dominating effects across the dose range. •Low-dose photon irradiations used in initiating structural alteration in carbon-rich materials.•Analysed via Raman and X-ray photo-spectroscopy, providing analysis of dose dependence.•Order-disorder via defect creation and annealing as competing dominant effects across dose range.•O1s/C1s ratio a potential parameter for dose dependent damage analysis in graphite.

    A. K. M. Mizanur Rahman, Mahfuza Begum, Mahbuba Begum, H. T. Zubair, H. A. Abdul-Rashid, Z. Yusoff, D. A. Bradley (2018)Radioluminescence of Ge-doped silica optical fibre and Al2O3:C dosimeters, In: Sensors and actuators. A. Physical270pp. 72-78 Elsevier

    Using an electron accelerator producing a 6 MV X-ray photon beam several experimentally observed excitation phenomena that are associated with radioluminescence (RL) have been investigated, the signal originating from a Ge-doped silica optical fibre and commercial nanoDot Al2O3:C dosimeters. Using PMMA optical communication fibres the RL signals have been guided from the beam-delivery room out to the readout instrumentation that has been located beyond the concrete maze providing effective radiation shield. Ge-doped silica fibre memory effects and afterglow (phosphorescence) were compared with that of the commercial Al2O3:C dosimeter. Immediately following RL, observation was made of the decay curves of the afterglow signal of Al2O3:C. Conversely, there was little practically observable afterglow for the Ge-doped fibre used for the majority of present investigations (the dopant concentration of this being 3.6 wt %). Among three different concentration of Ge-doped fibres that were subsequently investigated in a follow-up study, the intensity of afterglow was found to be greatest for the more highly doped concentration (7.0 wt % Ge), with progressive reduction of the effect for the Ge 4.7 wt % and Ge 3.6 wt % fibres. These observations can be compared against the much more marked RL memory effect observed using the Al2O3:C chips. Current results point to the Ge-doped silica optical fibre being a highly promising candidate for real-time RL dosimetry and sensing. (C) 2017 Elsevier B.V. All rights reserved.

    Pervaiz Ahmad, Mayeen Uddin Khandaker, Fida Rehman, Nawshad Muhammad, Mohammad Rashed Iqbal Faruque, Zahoor Ullah, Muhammad Abdul Rauf Khan, Ghulamullah Khan, Muhammad Imtiaz Khan, Hazrat Ali, Sirajul Haq, Yousaf Iqbal, Khalid Alzimami, Layal Jambi, David A. Bradley (2021)Facile Synthesis of High-Quality Nano-Size B-10-Enriched Fibers of Hexagonal Boron Nitride, In: Crystals (Basel)11(3) Mdpi

    The interesting properties of hexagonal boron nitride (h-BN) and its potential uses in thermo-structural advanced applications have been limited or restricted by its inherent brittleness, which can easily be eliminated by its fibers (h-BN) in nanoscale dimensions. The current study is based on the synthesis of nanoscale B-10-enriched fibers of h-BN ((10)BNNFs) from B-10 in the precursors instead of B in two-hour annealing at 900 degrees C and one-hour growth at 1000 degrees C. All of the (10)BNNFs are randomly curved and highly condensed or filled from (10)h-BN species with no internal space or crack. XRD peaks reported the (10)h-BN phase and highly crystalline nature of the synthesized (10)BNNFs. (10)h-BN phase and crystalline nature of (10)BNNFs are confirmed from high-intensity peaks at 1392 (cm(-1)) in Raman and FTIR spectroscopes.

    Samer K I Ali, Mayeen Uddin Khandaker, K S Al-Mugren, Sk A Latif, D A Bradley, A A Okhunov, A Sulieman (2021)Evaluation of production cross-sections for theranostic 67Cu radionuclide via proton-induced nuclear reaction on 68Zn target, In: Applied radiation and isotopes173pp. 109735-109735
    Sarah K. Albahiti, Rashid A. Barnawi, Khalid Alsafi, Mawya Khafaji, Rowa Aljondi, Salem Saeed Alghamdi, Zuhier Awan, Abdelmoneim Sulieman, Mustafa Jafer, Nissren Tamam, Abdulrahman Tajaldeen, Essam H. Mattar, Khaled Mudis Al-Malki, David Bradley (2022)Establishment of institutional diagnostic reference levels for 6 adult computed tomography examinations: Results from preliminary data collection, In: Radiation physics and chemistry (Oxford, England : 1993)201 Elsevier Ltd

    Computed tomography (CT) is the leading source of the cumulative effective doses to the general populace from medicinal and artificial sources. With the increased use of CT examinations comes the concern regarding the health effects of unnecessary radiation exposure and the need to optimize the doses that patients receive. The current study evaluates the patients' doses during specific CT procedures and establishes institutional diagnostic reference levels (DRLs) for the frequent CT scans performed. 8156 CT scan examinations were performed during three years from 2015 to 2018 using a single CT scan machine at our institution. Data from the six most common examinations were analyzed. The volume CT dose index (CTDIvol (mGy)) and dose length product (DLP) distribution's median and 75th percentile values were computed. The results were descriptively compared with DRLs from different countries and regions. The six most common examinations constituted 5815 studies. We established our DRLs as the median value of CTDIvol (mGy)| and DLP (mGy × cm) as follows: CT of the brain: 35.0 mGy and 839 mGy× cm, respectively; chest with contrast: 4 mGy and 148 mGy-cm, respectively; chest without contrast: 5 mGy and 190 mGy-cm, respectively; abdomen and pelvis with contrast: 8 mGy and 636 mGy-cm, respectively; abdomen and pelvis without contrast 8 mGy and 568 mGy-cm, in that order; abdomen, pelvis, and kidneys: 11 mGy and 458 mGy× cm, respectively. Our values for brain and chest CTs were lower than the international DRLs, while those for abdominal imaging were higher. The established DRLs offer an opportunity for us to optimize the dose delivered to patients and compare them to the national benchmarks when they are issued. The study revealed that CT dose showed wide discrepancies for the same procedures at the department levels suggesting that the practice was neither optimized nor harmonized. Therefore, DRL should be reassessed after the operators' training and awareness to reduce the patients' dose and related radiogenic risk to its minimal value. •DRL was quantified for six standard CT examinations.•The study revealed that CT dose showed wide discrepancies for the same procedures.•The proposed DRLs are within the international values.•DRL should be reassessed after the technologists' training on imaging protocol optimization.

    A. Basaif, Adebiyi Oresegun, H. T. Zubair, Hafiz Zin, K. Y. Choo, S. A. Ibrahim, Tingyu Wang, Jianxiang Wen, Dingpeng Gang, Elfed Lewis, H. A. Abdul-Rashid, D. A. Bradley (2023)Time-resolved radiation dosimetry using a cerium and terbium Co-doped YAG crystal scintillator, In: Radiation physics and chemistry (Oxford, England : 1993)204 Elsevier

    Time-resolved radiation dosimetry is an important factor in ensuring dose delivery during radiotherapy is within the prescribed doses for treatment. One method for time-resolved radiation dosimetry is by radioluminescence (RL) measurement technique using doped-silica optical fibre scintillators. The benefits of RL measurement technique include the capability to measure in real-time, high spatial resolution, and greater adaptability. Additionally, time-resolved dosimetry can be achieved by employing suitable scintillators with short rise and decay time. Silica optical fibre scintillators when doped with suitable dopants, provides the temporal resolution required for pulse-by-pulse dosimetry. Yttrium Aluminium Garnet (YAG) crystal optical fiber doped with Cerium and Terbium are discussed as a possible scintillator for time-resolved radiation dosimetry. The Cerium and Terbium co-doped YAG crystal scintillator samples are irradiated under a 6 MV photon beam from a Elekta Synergy (R) LINAC. The irradiation doses ranged from 100 cGy/min to 600 cGy/min. The measurements were made using an RL system with a gating time of 1 mu s. Linear RL response to dose of the irradiated scintillator samples was shown with minimal detectable memory, no afterglow or plateau effects. A rise time of 189.3 ns and a decay time of 260 ns were recorded, indicating promising potential for time-resolved radiation dosimetry.

    Y. Musa, S. Hashim, S. K. Ghoshal, D. A. Bradley, N. E. Ahmad, M. K. A. Karim, A. Hashim, A. B. A. Kadir (2018)General radiographic attributes of optically stimulated luminescence dosimeters: A basic insight, In: Radiation physics and chemistry (Oxford, England : 1993)147pp. 1-6 Elsevier

    We report the ubiquitous radiographic characteristics of optically stimulated luminescence dosimeters (OSLO) so called nanoDot OSLDs (Landauer Inc., Glendwood, IL). The X-ray irradiations were performed in free air ambiance to inspect the repeatability, the reproducibility, the signal depletion, the element correction factors (ECFs), the dose response and the energy dependence. Repeatability of multiple readouts after single irradiation to 10 mGy revealed a coefficient of variation below 3%, while the reproducibility in repeated irradiation readout-annealing cycles was above 2%. The OSL signal depletion for three nanoDots with simultaneous irradiation to 20 mGy and sequential readouts of 25 times displayed a consistent signal reduction approximate to 0.5% per readout with R-2 values over 0.98. ECFs for individual OSLDs were varied from 0.97 to 1.03. In the entire dose range under 80 kV, a good linearity with an R2 exceeding 0.99 was achieved. Besides, the percentage difference between OSLO and ion-chamber dose was less than 5%, which was superior to TLD. The X-ray photon irradiated energy response factors (between 0.76 and 1.12) in the range of 40-150 kV (26.1-61.2 keV) exhibited significant energy dependence. Indeed, the nanoDot OSLDs disclosed good repeatability, reproducibility and linearity. The OSLDs measured doses were closer to ion-chamber doses than that of TLD. It can be further improved up to a 3% by applying the individual dosimeter ECF. On top, the energy dependent uncertainties can be minimized using the energy correction factors. It is established that the studied nanoDot OSLDs are prospective for measuring entrance dose in general radiographic practices.

    K. S. Almugren, S. F. Abdul Sani, E. H. Uguru, N. H. Amiera Narissa, R. Zakaria, F. H. Alkallas, D. A. Bradley (2021)Measurement of photoelectron generation in a gold coated glass slide, In: Radiation physics and chemistry (Oxford, England : 1993)178 Elsevier

    In thin low-Z media irradiated by photon energies of several tens of keV, the presence of a high-Z additive can result in manifest locally modified secondary electron dose. Present study analyses the photoelectron dose enhancement resulting from nanometre thickness gold (atomic number Z = 78) coated on commercial borosilicate (B2O3) glass microscope cover-slips. Two thicknesses of B2O3 cover-slip have been utilized, 0.13 +/- 0.02 mm and 1.00 +/- 0.01 mm, with single-sided Au coatings of 20, 40, 60, 80 and 100 nm. An additional uncoated glass slide has been kept as a comparator. The samples have been exposed to X-rays generated at kVp potentials, delivering a fixed dose of 2 Gy. Dose enhancement resulting from the 1.00 mm glass has been observed to be similar to 1.32 x that of the 0.13 mm thickness glass. The elemental composition of the samples has been obtained via Electron Dispersive X-ray (EDX), elemental content differences between the two thicknesses of glass leading to a difference in effective atomic number of less than 0.3%. The influence on photon yield of the gold coating and variations in elemental content has been modelled using Monte Carlo simulation, allowing comparison with the measured values of enhanced TL yield.

    M.K. Muhamad Azim, S.F. Abdul Sani, E. Daar, M.U. Khandaker, K.S. Almugren, F.H. Alkallas, D.A. Bradley (2020)Luminescence properties of natural dead sea salt pellet dosimetry upon thermal stimulation, In: Radiation physics and chemistry (Oxford, England : 1993)176 Elsevier Ltd

    In the event of a radiological accident or attack, immediate need arises for reliable estimation of dose to the population from an affected environment. This would contribute to proper medical treatment and any need for isolation of affected areas. As such, it is important to improve dosimetry assessment through use of locally available materials, the latter acting as accident/prospective dosimeters. Present investigation has examined the TL properties of natural salt collected in Jordan, from the Dead Sea, and exposed using 60Co gamma radiation. Entrance doses ranging from 2 to 10 Gy have been delivered, providing desirable luminescence features. Natural Dead Sea NaCl are produced in cylindrical pellet form, achieved with 0.1 and 0.3 cm thickness sized from the salt grains obtained by a compression force of 5.0 ± 0.1 tonnes. With these NaCl pellets, linear dose response has been achieved, producing strong TL yield for a 0.1 cm thick layer, exceeding that of 0.3 cm thickness by a factor of 3. The shape of the glow curves was found to be independent of delivered dose, the main TL dosimetric peak remaining within the range 180 °C to 280 °C and 300 °C to 400 °C for the 0.1- and 0.3 cm NaCl pellets respectively. Computerised glow curve deconvolution was carried out, comprising of ten peaks, with associated activation energies and frequency factors. TL response per unit mass of NaCl pellets for both thicknesses were found to be energy dependent, predominating in yield at 60 keV. Over a period of 35 days the 0.3 cm NaCl pellet showed the least effect of fading, with loss of TL signals of 56% compared to an 81% loss for the 0.1 cm pellet. It is also noted that the combination of low activation energy and high frequency factors for the electrons to escape a trap for the 0.1 cm NaCl pellet samples subjected to 2 Gy gamma irradiation resulted in a highly substantial loss of TL signal over the first 7 days in comparison to the 0.3 cm NaCl pellet. Both samples thicknesses were unable to produce reproducible TL responses for the second and greater use. It has also been found that in addition to particle size, moisture and pre-irradiation annealing influence the TL properties. The excellent TL properties achieved by 0.1 cm NaCl pellets indicate their potential use as an accident/prospective dosimeter. •Two pellet thicknesses; 0.1- and 0.3 cm of natural dead sea salt.•TL yield of 0.1 cm thick provide linear dose response; 3 times greater than 0.3 cm.•Glow curve deconvolution of natural dead sea salt comprised of ten peaks.


    The present study concerns measurement of the radon concentration in drinking and irrigation waters obtained from the eastern part of Oman, in particular in regard to water quality assessment of the region. The samples were collected from different places covering most types of water sources in the region. A passive and time-integrated track etch detector (LR-115 type II) combined with a high-resolution optical microscope has been used to obtain the radon concentration in the studied samples. Values of dissolved radon in water varied among the water sources; the highest concentration of radon was found to be 363 Bq m-3 in a drinking water sample while well water used for irrigation showed the lowest value, at 140 Bq m-3. Measured data for all water sources are below the permissible limit of 11.1 kBq m-3 recommended by the US-EPA. Annual effective doses for the studied samples were in the range 0.38-0.99 μSv y-1 which is significantly less than the action level recommended by the WHO (0.1 mSv y-1), indicating that the water sources in the Jalan BBH region of Oman are safe to use. The obtained data may serve as a reference for any future radiological study of the waterbody of this region.

    Siti Nurasiah Mat Nawi, Mayeen Uddin Khandaker, S.F Abdul Sani, S.S. Ismail, K.S. Al-Mugren, Mohammad Amirul Islam, Kamrun Naher, D.A. Bradley (2021)Structural and dosimetric study of sub-kGy neutron-irradiated graphitic media, In: Radiation physics and chemistry (Oxford, England : 1993)189 Elsevier Ltd

    Associated with the marked difference between the mechanism of neutrons interactions relative to that of low linear-energy transfer (LET) radiations, few convenient dosimeters offer well differentiated measurement of neutron doses at useful sensitivity and spatial resolution. Present study has made use of highly uniform 2B and HB grade polymer pencil lead graphite (PPLG) (approximately 95 wt % and 61 wt % graphite content, respectively), addressing variation in lattice structure and defects resulting from sub-kGy neutron-doses. The latter have been provided by the TRIGA-II nuclear reactor located at the Bangladesh Atomic Energy Commission. Raman, photoluminescence (PL), and thermoluminescence (TL) techniques were used to perform structural and luminescence characterization of PPLGs. Comparison was made with highly-oriented pyrolytic graphite (HOPG), a pure ordered synthetic form of graphite. The dose-dependent defects produced in graphitic structures were characterized based on the Raman ID/IG intensity ratio, with observation of the Wigner effect. Analysis of PL spectra provides an average band gap energy in the range of 1.111–1.114 eV. All samples have been found to provide excellent linear response within the dose range 0–200 Gy, 2B grade PPLGs showing greater sensitivity compared to that of HB. The outcomes from this research may contribute to the development of cost effective, versatile graphite-based dosimeters, with particular applications to ionizing radiation dosimetry in clinical radiotherapy and industrial spheres. •Novel use of polymer pencil-lead graphite (PPLG) for radiation dosimetry.•This study performs structural and luminescence characterization of PPLGs.•2B grade commercially available PPLG shows the greatest sensitivity compared to others.•Studied sub-kGy dose (neutron) range are well suited to applications in radiotherapy and industrial spheres.•PPLG offers a viable alternative to current commercial dosimeters.

    Amjad Alyahyawi, Abdulaziz H. Alanazi, Mansour Almurayshid, Saad Alshahri, Meshari Almeshari, D.A. Bradley (2021)Off-the-shelf thermoluminescent silica glass media for use in medical diagnostic dosimetry applications, In: Applied radiation and isotopes178pp. 109953-109953 Elsevier Ltd

    In respect of radiation exposure assessments, thermoluminescent dosimeters (TLD) represent a notable and important subset of passive detector technology, gaining widespread use over a period of many decades, not least for medical applications. TLDs are available in a range of physical and chemical forms, in particular the popularity of phosphor-based commercial products arising from features that include availability down to low mm dimensions, soft-tissue equivalence in some cases, and relatively low TL fading. Novel doped silica glass TL material fabricated as fibres also offer favourable responses, recent developments in co-doping leading to their ability to also provide for diagnostic radiology applications, adding to the attractive features of being impervious to water, of good sensitivity, and generally offering wide dynamic range. Thus said, doping and fibre fabrication involve relatively high costs. Accordingly, herein exploratory investigations are made of the cost-effective colourless silica-based glass medium from which marbles are made, reduced into chip form for ease of application, examining sensitivity to dose. In particular, the study focuses on the computerised tomography clinical application regime, 80- to 140 kVp, with excellent response being shown for doses within the range 2- to 50 mGy. •Off-the-shelf thermoluminescent silica glass media.•Easily formed into cost effective convenient chip dosimeters.•Elemental and glow curve analysis points to soda-lime glass.•Tested in clinical CT dosimetry applications regime.

    Norfadira Binti Wahib, S F Abdul Sani, Ain Ramli, S S Ismail, Muhammad Hussin Abdul Jabar, M U Khandaker, E Daar, K S Almugren, F H Alkallas, D A Bradley (2020)Natural dead sea salt and retrospective dosimetry, In: Radiation and environmental biophysics59(3)pp. 523-537

    Accidents resulting in widespread dispersal of radioactive materials have given rise to a need for materials that are convenient in allowing individual dose assessment. The present study examines natural Dead Sea salt adopted as a model thermoluminescence dosimetry system. Samples were prepared in two different forms, loose-raw and loose-ground, subsequently exposed to Co gamma-rays, delivering doses in the range 2-10 Gy. Key thermoluminescence (TL) properties were examined, including glow curves, dose response, sensitivity, reproducibility and fading. Glow curves shapes were found to be independent of given dose, prominent TL peaks for the raw and ground samples appearing in the temperature ranges 361-385 ºC and 366-401 ºC, respectively. The deconvolution of glow curves has been undertaken using GlowFit, resulting in ten overlapping first-order kinetic glow peaks. For both sample forms, the integrated TL yield displays linearity of response with dose, the loose-raw salt showing some 2.5 × the sensitivity of the ground salt. The samples showed similar degrees of fading, with respective residual signals 28 days post-irradiation of 66% and 62% for the ground and raw forms respectively; conversely, confronted by light-induced fading the respective signal losses were 62% and 80%. The effective atomic number of the Dead Sea salt of 16.3 is comparable to that of TLD-200 (Z 16.3), suitable as an environmental radiation monitor in accident situations but requiring careful calibration in the reconstruction of soft tissue dose (soft tissue Z 7.2). Sample luminescence studies were carried out via Raman and Photoluminescence spectroscopy as well as X-ray diffraction, ionizing radiation dependent variation in lattice structure being found to influence TL response.

    F. Moradi, G. A. Mahdiraji, Kh Rezaee Ebrahim Saraee, M. U. Khandaker, F. R. M. Adikan, D. A. Bradley (2022)Impact of dosimeter size on energy dependence: An experimental study on glass TLDs, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier

    Practical Use of a dosimeter in a range of photon energies necessitates identification of radiation field as well as energy response of the dosimeter. Energy dependence of absorbed dose is caused by the unequal absorption properties of the material from various radiation energies, while the process of dosimeter response generation may also be energy dependent. The aim in this work is to measure the energy dependence of the response of submillimeter size glass silica fibre thermoluminescent dosimeters and to check whether there is a relation between energy dependence and the size of the dosimeter. Small size TLDs of capillary rod shape with the external/internal diameters of 870/544, 386/241 and 127/79 mu m and 3 mm length prepared by a precision cutting process and appropriate preconditioning, were irradiated at various photon energies. Irradiations were performed in free-in-air condition at the secondary standard dosimetry laboratory (SSDL) of the Malaysian Nuclear Agency using X-ray narrow series spectra and gamma rays from a137Cs source as the reference photon energy. Theoretical energy dependence calculated by using the cavity theory was found in an acceptable agreement with the experimental results. The results show an increasing degree of energy dependence with the dosimeter size in the studied size range. This can be explained based on the low dimensions of the dosimeter that are comparable with the range of secondary electrons produced in the dosimeter, while luminescence efficiency may also play a role.

    Maeve Masterson, George Wood-Stott, Shakardokht M. Jafari, David Bradley (2022)A review of micro silica beads in radiation dosimetry applications, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier

    A recent development in the field of radiation measurement is the use of silica glass beads as high performance thermoluminescent detectors. The application of using doped silica glass jewellery beads as radiation detectors was first proposed by Jafari in 2014, on the basis that it held the potential to resolve long standing issues in dosimetry, could be cheaply implemented, and had yielded good results in initial experimental work. Today the body of literature concerned with glass bead do-simeters has grown extensively, covering their behaviour in various radiation fields, as well as their handling and storage properties. The purpose of this review is to summarise the results obtained in the literature so far. Paramount among these is the finding that beads could offer excellent performance in radiotherapy appli-cations, particularly due to their small volume (1-3 mm3), measurement reproducibility of less than 3% (k = 2), chemical inertness and low fading rate (10% over the first 30 days after irradiation). The beads are energy independent over the MV photon and MeV electron energy ranges and exhibit good linearity in electron, proton, carbon ion and photon radiation (an R2 of 0.999 having been achieved from 1 cGy to 50 Gy in a 6 MV photon beam) as well as being dose-rate and angular in-dependent. However, significant energy dependence in the lower energy range is apparent (< 300 kV), thus careful calibration is required. Irradiation of beads with neutrons has also been studied, the reported results indicate their potential use as high spatial resolution alternatives to the gas detectors presently used in industrial and scientific fields. Published use cases of silica beads have been identified and summarised in this review, these include treatment plan verification, small field dosimetry, SABR audits and kV therapy all of which demonstrating the potential use for silica bead TLDs within Radiotherapy.

    D.A. Bradley, M.U. Khandaker, Abdulaziz Alanazi (2020)Irradiated glass and thermoluminescence yield: Dosimetric utility reviewed, In: Radiation physics and chemistry (Oxford, England : 1993)170 Elsevier Ltd

    With numbers of efforts being made towards harnessing the thermoluminescence yield of doped glass media for dosimetric applications, predominantly in the radiotherapeutic regime, review is provided of the background to this, tracing developments leading to the present day. Included are an examination of the relative strengths of the various TLD currently on offer and that of glass fabrications, commercial Ge-doped optical fibre as well as novel fibres fabricated from Ge-doped glass. The demands that modern radiotherapeutic dose delivery systems are placing upon these passive forms of dosimetry are reviewed together with the various responses arising from current efforts. Also reviewed are the basis of the luminescence yield, citing the defect types occurring in silica, even in the absence of extrinsic dopants. •Review of thermoluminescence yield of doped glass media for dosimetric applications.•Focuses on radiotherapeutic regime, addressing the various challenges of modern practices in radiation dosimetry.•Origin of the underpinning defects emphasised.

    S.S. Ismail, S.F. Abdul Sani, M.U. Khandaker, N. Tamchek, Julia A. Karim, K.S. Almugren, F.H. Alkallas, A.S. Siti Shafiqah, D.A. Bradley (2022)Dosimetric characteristics of Gd-doped silica glass subjected to neutron and gamma irradiations, In: Applied radiation and isotopes189pp. 110409-110409 Elsevier Ltd

    The dosimetric characteristics of newly developed gadolinium (Gd) glass dosimeter produced via sol-gel method are reported. Irradiation were made using a 750 kW neutron flux thermal power and 1.25 MeV 60Co gamma rays with entrance doses from 2 to 10 Gy. Investigation has been done on various Gd dopant concentrations, ranging from 1 to 10 mol%. The Gd-doped silica glass have been characterised for thermoluminescence (TL) dose response, sensitivity, linearity index, glow curve and kinetic parameter analysis. For particular dopant concentration obtained in 6 mol% Gd, the least squares fit shows the change in TL yield, correlation coefficient (r2) of better than 0.980 (at 95% confidence level), with neutron and gamma exposure to be 8 and 4 times greater than that of 1 mol% Gd, respectively. Broad peaks in the absence of any sharp peak observed in the glow curve confirms the amorphous nature of the prepared glass. A glow curve of Gd-doped SiO2 sample is observed with a single prominent peak (Tm) within 200–250 °C (peak shifting appears with respect to the increment of dopant concentration) and 350 °C (for all respective Gd dopants) for neutron and gamma irradiations, respectively. Deconvolution shows the glow curves of the Gd-doped SiO2 glass to be formed of seven and five overlapping peaks, with figures of merit below 2% (FOM) of between 1.38-1.79 and 1.30–1.97 for the particular neutron and gamma irradiations, respectively. Through use of Glowfit deconvolution software, the key trapping parameters of activation energy, E and frequency factor, s−1 were calculated for the Gd-doped SiO2 glass. The mechanism of TL yield with the gradual increase in Gd concentrations and doses is explained upon the incorporation of Gd and radiation damage that change the structure of the electron traps in the glass matrix. These early results indicate that selectively screened Gd-SiO2 glass can be developed into a promising TL system towards dosimetric applications. •We provide experimental report for our work on tailor made gadolinium doped silica glass.•The construction and performance of a TL emission spectra facility is described.•TL intensity of TL spectra were influenced by Gd concentration and radiation dose.•6mol% of Gd show great promise for use as next-generation radiation dosimeters.

    Y. Musa, S. Hashim, S. K. Ghoshal, N. E. Ahmad, D. A. Bradley, M. K. A. Karim, A. Sabarudin (2019)Effectiveness of Al2O3:C OSL dosimeter towards entrance surface dose measurement in common X-ray diagnostics, In: Radiation physics and chemistry (Oxford, England : 1993)165 Elsevier

    We report the successful use of nanoDots Optically Stimulated Luminescence Dosimeters (OSLDs) for the determination of the entrance surface dose (ESD) in common X-ray diagnostics. ESD evaluation is made on six radiographic projections including abdomen (AP and LAT), chest (AP and PA), skull (AP), and thoracic spine (AP). Indirect and direct ESD measurements have been performed with and without whole-body anthropomorphic phantom using GE radiography system installed at the Diagnostic Imaging Laboratory, Universiti Kebangsaan Malaysia (UKM), wherein the International Atomic Energy Agency protocol (IAEA TRS-457) has been followed. The CALDose_X 5.0 software is used to calculate ESDs in these projections. The mean ESDs obtained with indirect measurements for AP abdomen, LAT abdomen, AP chest, PA chest, AP thoracic spine, and AP skull projections are 4.8, 8.3, 0.7, 0.2, 7.2, and 3.7 mGy respectively, and with direct measurements, the respective mean ESDs are 4.3, 8.3, 0.7, 0.3, 6.8, and 2.8 mGy. The values obtained by CALDose_X calculations are 8.3, NA, 1.1, 0.7, 8.8, and 4.5 mGy, respectively. Significant variations ranging from 18% to 59% are observed between measured and calculated ESDs, which are attributed to the difference in phantom size and field size. The overall uncertainty for direct measurements has a maximum of +/- 0.86 mGy compared to +/- 0.47 mGy for indirect measurement. Measured ESDs are within the IAEA and European Commission (EC) DRLs range, while calculated ESDs are slightly above the measured values. It is concluded that the use of nanoDots OSLD is beneficial for ESD measurement in routine X-ray examinations.

    Sezai Yalcin, Urkiye Akar Tarim, Orhan Gurler, Ozcan Gundogdu, D. A. Bradley (2021)Screening parameter for elastic scattering of electrons, In: Radiation effects and defects in solids176(9-10)pp. 919-939 Taylor & Francis

    The present work, with its interest focusing on the elastic scattering of energetic electrons, provides a novel formulation that is demonstrated to give accurate values of the screening parameter. This is a matter considered vital in obtaining transport cross-sections, the work herein covering not only a wide range of electron energies popular in applications (1-3000 keV) but also a comprehensively wide range of target atomic numbers (Z: 1-94). Such ability has hitherto not been commonly available in making use of existing formulations. Results from the proposed formula together with comparisons made against previously published results are presented for seventeen representative elements, covering the energy range 1 keV to 3 MeV, providing a representative condensation from the 94 elements for which we have made comparable calculations. The new formulation is seen to offer a viable and accurate approximation, being both simple to apply and devoid of limitations within the bracketed electron energy and target atomic number ranges.

    Ming Tsuey Chew, David A. Bradley, Masao Suzuki, Naruhiro Matsufuji, Takeshi Murakami, Bleddyn Jones, Andrew Nisbet (2019)The radiobiological effects of He, C and Ne ions as a function of LET on various glioblastoma cell lines, In: Journal of radiation research60(2)pp. 178-188 Oxford Univ Press

    The effects of the charged ion species He-4, C-12 and Ne-20 on glioblastoma multiforme (GBM) T98G, U87 and LN18 cell lines were compared with the effects of 200 kVp X-rays (1.7 keV/pm). These cell lines have different genetic profiles. Individual GBM relative biological effectiveness (RBE) was estimated in two ways: the RBE10 at 10% survival fraction and the RBE2 Gy after 2 Gy doses. The linear quadratic model radiosensitivity parameters alpha and beta and the alpha/beta ratio of each ion type were determined as a function of LET. Mono-energetic He-4, C-12 and Ne-20 ions were generated by the Heavy Ion Medical Accelerator at the National Institute of Radiological Sciences in Chiba, Japan. Colony-formation assays were used to evaluate the survival fractions. The LET of the various ions used ranged from 2.3 to 100 keV/mu m (covering the depth-dose plateau region to clinically relevant LET at the Bragg peak). For U87 and LN18, the RBE(10 )increased with LET and peaked at 85 keV/mu m, whereas T98G peaked at 100 keV/mu m. All three GBM alpha parameters peaked at 100 keV/mu m. There is a statistically significant difference between the three GBM RBE10 values, except at 100 keV/pm (P < 0.01), and a statistically significant difference between the a values of the GBM cell lines, except at 85 and 100 keV/mu m. The biological response varied depending on the GBM cell lines and on the ions used.

    Halmat J. Hassan, S. Hashim, N.Z.H. Abu Hanifah, M.S.M. Sanusi, M.R. Fahmi, R.M. Tahar, D.A. Bradley (2022)External dose assessment of NORM added consumer products using Geant4 Monte Carlo simulations, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    Radioactive consumer products (RCP) are widely marketed for everyday use. The study herein was conducted on 21 commercially available RCP, including bio-glass discs, energy cards, scalar energy products, and anti-radiation stickers, all purposefully designed to contain naturally occurring radioactive material (NORM). This study investigates the dose influence of such consumer products which acts as external radiation sources that may be in contact with human body. The goal of this study is to assess the potential risk of using NORM-added consumer products, the presence of such products in the living environment unnecessarily exposing members of the public to radiation. A Pb-shielded high purity Ge (HPGe) spectrometer was used to perform the analysis of samples radioactivity levels. Simulations were performed using Geant4 Monte Carlo (GMC) simulations to estimate the equivalent organ doses and annual effective dose (AED) in the use of such products. The total activity in such radioactive consumer products ranges from 2.0 ± 0.1 to 7413 ± 576 Bq, 1.9 ± 0.8 to 1168 ± 131 Bq, and 21 ± 5–574 ± 103 Bq, for 232Th, 238U, and 4 K, respectively. It was found that RCP contains monazite, giving a relatively high concentration of uranium and thorium. The radiological risk posed by the use of such items as healthcare products is assessed, with the daily external exposure doses of particular concern. Dose assessments of the organ equivalent and average effective doses were performed by measuring the activity of 232Th, 238U, and 4 K using the aforementioned products for various exposure duration scenarios. Accordingly, sample A13 a bio-glass disc offered concentrations with mean percentages of 1.29 ± 0.003% and 0.043 ± 0.0003% for Th and U, respectively, giving rise to estimate the greatest annual effective dose exposure of 2.54 mSv among samples, considerably in excess of the public dose limit of 1 mSv y-1 •Radioactivity levels contain in NORM-added consumer products been evaluated using HPGe.•Annual effective dose of using radioactive consumer product (RCP) been evaluated.•External dose exposure from using RCP been assessed using Monte Carlo simulation.•Recommendation of prohibiting RCP is made, to prevent unnecessary radiation exposure.

    H.T. Zubair, R. Rifiat, Adebiyi Oresegun, F. Hamidi, J. Othman, M.D. Khairina, A. Basaif, S.A. Ibrahim, H.A. Abdul-Rashid, D.A. Bradley (2021)Fiber optic coupled survey meter for NORM and low-level radioactivity monitoring, In: Radiation physics and chemistry (Oxford, England : 1993)188 Elsevier Ltd

    Currently existing low-level gamma-ray monitoring and measurement devices in the oil and gas and minerals beneficiations industries have several operational limitations, typically including an inability to be operated in an intrinsically safe mode, restrictions in making remote measurements, and an inability to operate in aqueous or high temperature environments. Herein, characterization is made of an optical fiber system based on a LYSO:Ce scintillator, investigated at dose rates and contamination levels comparable to that in dealing with NORM. The measurements were calibrated against a Geiger Muller (GM) pancake counter. The scintillators produce radioluminescence (RL), propagating in the optical fiber waveguide to the photodetection system, providing real-time, remote and intrinsically safe radiation measurements of NORM and other low-level gamma emissions. The response has been found to be dependent on the orientation of the scintillator axis with respect to the source centre. The LYSO:Ce scintillator has been found to be responsive to naturally radioactive sources, tested using monazite and xenotime offering in-contact dose rates down to 20 μSv/h. The measurements were found to be comparable to that of the GM based measurements, further providing intrinsically safe RL remote capabilities, the study pointing to the potential use of scintillation based optical fiber dosimetry systems for NORM and low gamma-ray level measurement in a variety of industrial scenarios. •Fiber optic coupled radiation sensor for NORM sample dose rate measurement.•Sub-cm LYSO:Ce scintillator diameter.•Sensitivity of 45 cpm/μSv/h during remote measurements (Cs-137).•Probe is intrinsically safe, and resistant to water and electromagnetic interference.

    K.S. Almugren, S.F. Abdul Sani, Irzwan Affendy Sulong, S.N. Mat Nawi, A.S. Siti Shafiqah, D.A. Bradley (2022)Structural and defect changes in black carbon charcoal irradiated with gamma ray, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    This study investigates the use of black carbon charcoal as passive radiation dosimetry, offering low dependence on photon energy and near soft tissue effective atomic number with state-of-the-art techniques. Regression analyses have now been conducted using graphite manufactured commercially in the form of charcoal from three different types: mangrove, coconut, and green charcoal recycled from sawdust, working with photon-mediated interactions at radiotherapy dose levels. Explorations of changes in Raman spectroscopic characteristics, and photoluminescence dose dependence have been performed with a focus on the relationship between absorbed radiation energy and induced material changes, using a 60Co gamma-ray source doses ranging from 0 to 10 Gy. Raman spectroscopy has established to be an effective method for exploring defects in carbon-based materials due to its high sensitivity, most commonly focusing on the use of ID/IG parameter. While photoluminescence analysis will provide information on electronic properties and the band gap energy. The crystal structure of the black charcoal samples was characterised using X-ray diffractometry, with the goal of determining the degree of structural order, atomic spacing, and lattice constants of the various irradiated charcoal samples, supported by crystallite size assessments. The findings of this study could pave the way for a low-cost yet highly effective system for studying radiation-induced changes in carbon, as well as offering a viable alternative to current commercial dosimeters, well suited to applications in radiotherapy. •Radiation induced defect in charcoal exposed to 60Co gamma irradiation.•Raman D peak of three charcoals is ranging from 1344 to 1352 cm−1, while G peak is ranging from 1581 to 1585 cm−1.•The band gap energy for charcoal is found to be 1.111 ± 0.091 eV.•XRD spectra shows asymmetric shape of the (002) peaks.•Charcoal have Zeff values ranging from 6.65 to 6.74

    Nissren Tamam, Abdelmoneim Sulieman, D.A. Bradley (2023)Evaluation of patients doses at medical imaging departments, In: Radiation physics and chemistry (Oxford, England : 1993)203 Elsevier Ltd

    Radiation exposures for medical purposes is remained the main sources to public from manmade radiation. The aims of the study are to patients’ radiation doses during specific planar radiography procedures. A total of 247 patients were examined at four radiology department in Khartoum state, Sudan. The absorbed dose to air at the center of the beam, including backscattered radiation, is known as the entrance surface air kerma (ESAK, mGy). ESAK (Ke) can be computed using the product backscatter factor (B) and incident air kerma Ki. The mean ESAK (mGy) for the chest, skull, abdomen, hip, lumbar spine and limbs procedures were 0.2, 0.76, 97, 1.88, 1.25, 2.25 and 0.30 mGy, respectively. The average ESAK (mGy) values attained for eight planar radiography procedures are comparable or slightly lesser than the previously published studies for the chest, pelvis, and limbs. The patient doses during the skull, abdomen, hip, and spinal cord (lumbar spine) are lower than the previously published values. •ESAK during eight planar imaging procedures were evaluated.•The radiographic equipment performance in all hospitals was acceptable.•Wide variability in the patients' doses per radiographic was noticed.•Standardized imaging protocols are recommended.

    Ming Tsuey Chew, Andrew Nisbet, Bleddyn Jones, Masao Suzuki, Naruhiro Matsufuji, Takeshi Murakami, David A. Bradley (2019)Ion beams for space radiation radiobiological effect studies, In: Radiation physics and chemistry (Oxford, England : 1993)165 Elsevier Ltd

    Space radiation exposures to the heavier particles found in galactic cosmic rays (GCR) present a risk in manned space travel, particularly to the central nervous system (CNS). GCR are made up of a mixture of multiple charged particles such as protons, 4He, and 56Fe heavy ions. The most harmful to the CNS are the more highly charged and energetic (HZE) particles, including 56Fe because of their significant biological effect contribution to GCR dose and high linear energy transfer. These HZE particles can result in altered cognitive function, reduced motor function and behavioural changes and long term chronic brain disease. There is currently a lack of data on the biological response to 56Fe ions. In this regard, ground based experiments could be used to infer the effects of the cosmic environment on cell survival. A mono-energetic beam of 56Fe ions was generated by the Heavy Ion Medical Accelerator Chiba, National Institute of Radiological Sciences, Chiba, Japan. Three different types of glioblastoma multiforme (GBM) cell lines were studied. Using GBM cell lines which arise from the glia cells could aid in the understanding of the effects of space radiation to the brain. Clonogenic assay was used to determine the efficacy of the radiations. Certain strains of GBM are low-dose hypersensitive and hence, the very low doses used to study space radiation here are relevant. Results show that 0.2 Gy 56Fe (500 MeV/- 200 keV/μm) ions were able to inactivate approximately 8% of T98G, 15% LN18 and 27% of U87 cells. These results may infer and demonstrate the deleterious effects of 56Fe ions on human CNS, since a significant percentage of GBM cells were killed at very low doses. The data presented may therefore be employed in assessing risk related to high LET radiation exposure, simulating the effects in space radiation. •Space radiation exposures are a risk to the central nervous system.•There is a lack of data on the biological response to 56Fe ions.•Even low dose of 0.2 Gy of 56Fe ions has deleterious effects on glioblastoma cells.•Data presented could be used to assess risk related to high LET space radiation exposure.

    D. A. Bradley, R. Zainon (2020)Current and future direction of radiation physics in medicine, In: Radiation physics and chemistry (Oxford, England : 1993)176 Elsevier
    A. Basaif, Adebiyi Oresegun, Zubair H. Tarif, Hafiz Zin, K.Y. Choo, S.A. Ibrahim, H.A. Abdul-Rashid, D.A. Bradley (2021)Ge-doped silica optical fibre for Time Resolved Radiation Dosimetry, In: Radiation physics and chemistry (Oxford, England : 1993)189 Elsevier Ltd

    Time-resolved radiation dosimetry in radiotherapy helps determine the quality of delivery of patient prescribed doses. Earlier reports on doped silica optical fibres as scintillators in radioluminescence (RL) based radiation dosimetry have indicated particular merits, including versatility, robustness, high spatial resolution, wide dynamic range, and the ability for real-time measurements. Time-resolved radiation dosimetry requires high temporal resolution, enabled using a suitable scintillator and high-speed electronics. We report on the potential of Ge-doped optical fibres as a suitable scintillator to be adopted for use in a time-resolved radiation dosimetry system. High-energy clinical X-ray beams (6 MV) were used to irradiate the Ge-doped optical fibre samples. RL responses were recorded for six dose-rates (between 100 MU/min and 600 MU/min) delivered by a Varian 2100 C/D linear accelerator. The photon-counting circuit gating time was set at its shortest capability of 100 μs? The Ge-doped optical-fibre scintillator showed linear RL response, with minimal observable memory and afterglow and plateau effects. The fluorescence lifetime analysis, demonstrate a calculated rise time of 590.1 ns and a decay time of 0.423 μs, indicating superior performance compared to other scintillator forms. These results demonstrate the potential for the Ge-doped optical-fibre scintillator to be used in a time-resolved radiation dosimetry system. •Manuscript Number: RPC-D-21-00446.•Ge-doped Silica Optical Fiber for Time Resolved Radiation Dosimetry.•Time-resolved radiation dosimetry at 100 μs gating time using Ge-doped Silica Optical Fiber as a scintillator.•Linear response with minimal observable memory and afterglow and plateau effects.•The fluorescence lifetime analysis, demonstrate a calculated rise time of 590.1 ns and a decay time of 0.423 μs.

    Yeh Siang Lau, Ming Tsuey Chew, Amal Alqahtani, Bleddyn Jones, Mark A. Hill, Andrew Nisbet, David A. Bradley (2021)Low Dose Ionising Radiation-Induced Hormesis: Therapeutic Implications to Human Health, In: Applied sciences11(19) Mdpi

    The concept of radiation-induced hormesis, whereby a low dose is beneficial and a high dose is detrimental, has been gaining attention in the fields of molecular biology, environmental toxicology and radiation biology. There is a growing body of literature that recognises the importance of hormetic dose response not only in the radiation field, but also with molecular agents. However, there is continuing debate on the magnitude and mechanism of radiation hormetic dose response, which could make further contributions, as a research tool, to science and perhaps eventually to public health due to potential therapeutic benefits for society. The biological phenomena of low dose ionising radiation (LDIR) includes bystander effects, adaptive response, hypersensitivity, radioresistance and genomic instability. In this review, the beneficial and the detrimental effects of LDIR-induced hormesis are explored, together with an overview of its underlying cellular and molecular mechanisms that may potentially provide an insight to the therapeutic implications to human health in the future.

    Amal Alqahtani, D.A. Bradley, Abdulaziz Alanazi, Andrew Nisbet (2020)Characterisation of borosilicate glass media as potential thermoluminescent dosimeters, In: Radiation physics and chemistry (Oxford, England : 1993)168 Elsevier Ltd

    Thermoluminescence dosimetry applications range from environmental radiation monitoring to sensing of the doses delivered in radiotherapy, through to verifying the doses of large-scale industrial irradiation. Particular utilisations largely depend upon the sensitivity of the dosimetric medium. In present work the thermoluminescent dosimetric properties of commercial low-cost borosilicate glass slides and glass-fibre filters were characterized, use being made initially of a 250 kV clinical therapy x-beam facility. From this, reproducibility and linearity were determined for radiation doses of 0.5, 1, 2, 4, 6, 8, and 10 Gy. Reproducibility of +/5% was obtained following appropriate screening, excellent linearity to dose also being demonstrated for both the borosilicate glass slides and glass-fibre filters, sufficient to demonstrate the potential of these media for use in radiotherapy dosimetry. Of note is the appreciable but not unsurprising dose response of the nominal 1.0 mm thickness borosilicate glass slides, with a per unit dose response some twice that of the less substantial glass-fibre filters. Further work has characterized the borosilicate glass slides for the megavoltage photons and electrons produced by linacs. A further potential interest results from the boron content, recognizing the associated appreciable neutron cross-sections. It is posited that the additional response observed at 10 MV over that at 6 MV is partly a result of photo-neutron production, a matter that is expected to form the basis of further investigations. •Comparison of the thermoluminescence response of three glass-based media.•Characterization using orthovoltage x-ray photons.•Linearity of borosilicate glass demonstrated for megavoltage photons and MeV electrons.

    Ming Tsuey Chew, David A. Bradley, Bleddyn Jones, Andrew Nisbet, Mark Hill (2022)Review of the effect of reduced levels of background radiation on living organisms, In: Radiation physics and chemistry (Oxford, England : 1993)200 Elsevier Ltd

    It is well understood that all life is subject to continuous low levels of ionizing radiation, most prominently from the natural background of the biosphere, differing appreciably in particular situations across the surface of the globe. Added to this, albeit in much more isolated situations inclusive of particular workplaces and different environments, are exposures from ionizing radiations traced to human activities. Accordingly, studies of the effects of background-level radiations are subject to complex multifactorial influences. The radiation safety regulations and limits for lower levels of exposure are based on extrapolation from more elevated doses and dose rates, embodied in the linear no-threshold (LNT) model. The LNT model assumes the relationship between biological effects and radiation dose at low levels to be linear, all doses in excess of normal background carrying risk. Substantiated for high dose exposures, the validity of the model is unknown for low doses, the elucidation of possible beneficial hormetic and adaptive effects remaining a challenge. Herein, an overview of the effect on organisms of reduced low-levels of radiations is presented using available evidence and discussion of theoretical possibilities. •Earth's low natural background radiation and cosmic rays are relevant during the evolution of living organisms.•Effects of background-level radiations are subject to complex multifactorial influences.•Low-level background radiations could be beneficial to organisms.•Possibilities of harnessing the benefits of low-level background radiations.

    K Ley, S.A Hashim, A Lohstroh, C Shenton-Taylor, D.A Bradley (2021)Fading and residual responses for thermoluminescent dosimetry of silica beads irradiated using a high-dose electron-beam, In: Radiation Physics and Chemistry (Oxford, England : 1993)182109366 Elsevier Ltd

    Thermoluminescent (TL) glow-curves of 10 different coloured Toho Japan bead types have been obtained using a Risø TL/OSL reader studied for a fading period of 6 months as well as for residual dosimetry for fading up to 16 months after irradiation. For the entirety of the delay period studied the Frosted beads showed the largest TL response followed by Pink and Rose beads. Pink beads showed the best fit to the second order polynomial fit applied to the observed fading. In a more detailed dose curve fitted for a 6 month delay between irradiation and readout in order to determine the nature of the TL response as a function of increasing dose, it was found to follow the same trend for all bead colours. The residual TL response was also studied for beads that showed a large TL response. In these studies all colours showed similar dose response curves to those for the 1st readout, with Pink beads showing the best agreement to the fit applied to model fading. •TL response measured for electron beam irradiation of 1 kGy to 250 kGy, for 10 colours of beads.•The fading effect on TL response was studied in depth for Pink beads over a 16-month period.•Greatest TL produced from Pink and Frosted beads, Green and Lime beads show no correlation.•A detailed comparison of dose dependence with a 6 month fading time was evaluated for Pink beads.•All beads were evaluated for residual dosimetry at a fading time of 3 weeks.

    AL Palmer, D Bradley, A Nisbet (2014)Evaluation and implementation of triple-channel radiochromic film dosimetry in brachytherapy, In: JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS15(4)pp. 280-296 MULTIMED INC
    AL Palmer, DA Bradley, A Nisbet (2015)Evaluation and mitigation of potential errors in radiochromic film dosimetry due to film curvature at scanning, In: JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS16(2)pp. 425-431 MULTIMED INC
    E Dalah, D Bradley, A Nisbet (2010)A mathematical approach towards simulating a realistic tissue activity curve of Cu-64-ATSM for the purpose of sub-target volume delineation in radiotherapy, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT619(1-3)pp. 283-286
    EZ Dalah, A Nisbet, D Bradley (2010)Effect of window level on target volume delineation in treatment planning, In: APPLIED RADIATION AND ISOTOPES68(4-5)pp. 602-604
    J Cottee, A Lopez-Aviles, K Behzadian, D Bradley, D Butler, C Downing, R Farmani, J Ingram, M Leach, A Pike, L De Propris, L Purvis, P Robinson, A Yang (2016)The Local Nexus Network: Exploring the Future of Localised Food Systems and Associated Energy and Water Supply, In: R Setchi, RJ Howlett, Y Liu, P Theobald (eds.), Sustainable Design and Manufacturing 2016 (Smart Innovation Systems and Technologies). Special Volumepp. 613-624 Springer

    This volumes consists of 59 peer-reviewed papers, presented at the International Conference on Sustainable Design and Manufacturing (SDM-16) held in Chania, Crete Greece in April 2016. Leading-edge research into sustainable design and manufacturing aims to enable the manufacturing industry to grow by adopting more advanced technologies, and at the same time improve its sustainability by reducing its environmental impact. SDM-16 covers a wide range of topics from sustainable product design and service innovation, sustainable process and technology for the manufacturing of sustainable products, sustainable manufacturing systems and enterprises, decision support for sustainability, and the study of societal impact of sustainability including research for circular economy. Application areas are wide and varied. The book will provide an excellent overview of the latest research and development in the area of Sustainable Design and Manufacturing.

    AL Palmer, A Nisbet, DA Bradley (2013)Semi-3D dosimetry of high dose rate brachytherapy using a novel Gafchromic EBT3 film-array water phantom, In: 7TH INTERNATIONAL CONFERENCE ON 3D RADIATION DOSIMETRY (IC3DDOSE)444pp. ?-?
    DA Bradley, RP Hugtenburg, AL Yusoff (2006)At-edge minima in elastic photon scattering amplitudes for dilute aqueous ions, In: RADIATION PHYSICS AND CHEMISTRY75(11)pp. 1676-1682
    AT Abdul Rahman, SF Abdul Sani, DA Bradley (2012)Doped SiO 2 telecommunication fibre as a 1-D detector for radiation therapy dosimetry, In: AIP Conference Proceedings1423pp. 347-353

    Present studies concern Ge-doped SiO2 telecommunication fibre as a high spatial resolution 1-D thermoluminescence (TL) system for radiotherapeutic dosimetry. Using tube xray bremsstrahlung sources operating at kilovoltage energies, these fibres have been shown to offer linear response, from < 1Gy up to in excess of 30 Gy. Measurement of the photoelectron dose enhancement resulting from use of a moderately high atomic number medium (iodinated contrast media) demonstrates the fibres to have the local dose sensitivity required of interface dosimetry. In PMMA, the TL yield is ~60% greater in the presence of iodine than in its absence.

    Shakardokht Jafari, Clare Gouldstone, Peter Sharpe, Amani Alalawi, David Bradley, Catharine Clark, Andrew Nisbet, Nicholas Spyrou (2018)Low-cost commercial glass beads as dosimeters in radiotherapy
    E Daar, L King, A Nisbet, Rex Thorpe, DA Bradley (2010)Viscosity changes in hyaluronic acid: Irradiation and rheological studies, In: APPLIED RADIATION AND ISOTOPES68(4-5)pp. 746-750
    H Al-Sulaiti, T Nasir, PH Regan, D Bradley, K Al-Mugren, N Alkhomashi, N Al-Dahan, M Al-Dosari, SJ Bukhari, M Matthews, T Santawamaitre, D Malain, A Habib (2014)Effect of the grain size of the soil on the measured activity and variation in activity in surface and subsurface soil samples, In: Pakistan Journal of Scientific and Industrial Research Series A: Physical Sciences57(3)pp. 129-138

    Correlation between grain size and activity concentrations of soils and concentrations of various radionuclides in surface and subsurface soils has been measured for samples taken in the State of Qatar by gamma-spectroscopy using a high purity germanium detector. From the obtained gamma-ray spectra, the activity concentrations of the 238U (226Ra) and 232Th (228Ac) natural decay series, the long-lived naturally occurring radionuclide 40K and the fission product radionuclide 137Cs have been determined. Gamma dose rate, radium equivalent, radiation hazard index and annual effective dose rates have also been estimated from these data. In order to observe the effect of grain size on the radioactivity of soil, three grain sizes were used i.e., smaller than 0.5 mm; smaller than 1 mm and greater than 0.5 mm; and smaller than 2 mm and greater than 1 mm. The weighted activity concentrations of the 238U series nuclides in 0.5-2 mm grain size of sample numbers was found to vary from 2.5±0.2 to 28.5±0.5 Bq/kg, whereas, the weighted activity concentration of 40 K varied from 21±4 to 188±10 Bq/kg. The weighted activity concentrations of 238U series and 40 K have been found to be higher in the finest grain size. However, for the 232Th series, the activity concentrations in the 1-2 mm grain size of one sample were found to be higher than in the 0.5-1 mm grain size. In the study of surface and subsurface soil samples, the activity concentration levels of 238 U series have been found to range from 15.9±0.3 to 24.1±0.9 Bq/kg, in the surface soil samples (0-5 cm) and 14.5±0.3 to 23.6±0.5 Bq/kg in the subsurface soil samples (5-25 cm). The activity concen- trations of 232Th series have been found to lie in the range 5.7±0.2 to 13.7±0.5 Bq/kg, in the surface soil samples (0-5 cm) and 4.1±0.2 to 15.6±0.3 Bq/kg in the subsurface soil samples (5-25 cm). The activity concentrations of 40K were in the range 150±8 to 290±17 Bq/kg, in the surface soil samples (0-5 cm) and 129±7 to 299±14 Bq/kg, in the subsurface soil samples (5-25 cm). The activity concentrations of 238U series, 232Th series and 40K in the surface and deep soil samples are approximately same. The 137Cs activity concentration levels in surface soil samples in four sites were found to be higher than those observed for the soil samples that been collected at a depth of 5-25 cm. They ranged from 1.65±0.22 to 19.0±0.9 Bq/kg, in the surface soil samples (0-5 cm) and 0.5±0.2 to 15.4±0.7 Bq/kg, in the subsurface soil samples (5-25 cm).

    AS Habib, DA Bradley, PH Regan, AL Shutt (2010)The use of MCNP and gamma spectrometry in supporting the evaluation of NORM in Libyan oil pipeline scale, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT619(1-3)pp. 245-251
    S M Jafari, G Distefano, D Bradley, N M Spyrou, A Nisbet, C H Clark (2014)Validation of glass bead TLDs for radiotherapy treatment verification, In: Radiotherapy and Oncology111(1)PO-0793pp. p317-317 0167-8140
    ATA Rahman, DA Bradley, SJ Doran, B Thierry, E Braeuer-Krisch, A Bravin (2010)The thermoluminescence response of Ge-doped silica fibres for synchrotron microbeam radiation therapy dosimetry, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT619(1-3)pp. 167-170
    F Issa, RP Hugtenburg, DA Bradley, A Nisbet (2012)Investigating radionuclide source shielding performance using Ge-doped optical fibre thermoluminescence dosimeters, In: AIP Conference Proceedings1423pp. 401-405
    RP Hugtenburg, DW England, DA Bradley (2007)Near-edge elastic photon scattering in amorphous systems, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS263(1)pp. 22-26
    S Hashim, DA Bradley, MI Saripan, AT Ramli, H Wagiran (2010)The thermoluminescence response of doped SiO2 optical fibres subjected to fast neutrons, In: APPLIED RADIATION AND ISOTOPES68(4-5)pp. 700-703
    DA Bradley, RP Hugtenburg, S Hashim, OO Okoya, AL Yusoff, AAM Hassan, AT Ramli, H Wagiran (2007)The development of doped radiosensitive glass, In: KHB Senin, NH Idris (eds.), Solid State Science and Technology909pp. 9-18
    Amani Alalawi, Shakardokht Jafari, M Najem, K Clark, A Nisbet, F Abolaban, R Hugtenburg, M Hussein, Khalid Alzimami, N Spyrou, D Bradley (2013)Comparison of Ge-doped TL optical fibres and glass beads with ion chamber and Gafchromic film for small field photon dosimetry, In: 1st International Conference on Dosimetry and its Applications - Book of abstractspp. pp1-206 České vysoké učení technické v Praze Fakulta jaderná a fyzikálně inženýrská

    Small field (≤ 4 × 4 cm) photon radiotherapy treatments include intensity-modulated radiation therapy (IMRT)and stereotactic body radiation therapy (SBRT). These require small, high spatial resolution dosimeters of adequate dynamic range. In this study, field sizes of 1 cm × 1 cm, 2 cm × 2 cm, 3 cm × 3 cm, 4 cm × 4 cm, and 10 cm × 10 cm have been investigated using commercially available silica-based fibres and glass beads (GB) as TL dosimeters and a Varian linear accelerator operating at 6, 10 and 15 MV. Ge-doped SiO2 fibres have previously been shown by this group to offer a viable system for use as dosimeters. The fibres and GB, offer good spatial resolution (∼120 μm and 2 mm respectively), large dynamic dose range (with linearity from tens of mGy up to well in excess of many tens of Gy), a non-hygroscopic nature and low cost. The main aim of this present work is to investigate the use of Ge-doped optical fibres and GBs as thermoluminescence dosimeters in small photon fields for different photon beam energies, comparing the measurements against Gafchromic films, hospital commissioning data obtained from small ionisation chambers and photon diodes and Monte Carlo simulations with FLUKA and BEAMnrc.

    DA Bradley, AZ Aziz, AJ Knapton, HA Abdul-Rashid, AKMM Rahman, YM Amin, RM Nor, MJ Maah, R Mahat (2013)Optically Stimulated Luminescence in Beta Irradiated Ge-doped Optical Fibre, In: F Abdullah (eds.), 2013 IEEE 4TH INTERNATIONAL CONFERENCE ON PHOTONICS (ICP)pp. 38-40 IEEE
    DA Bradley, P Muthuvelu, RE Ellis, EM Green, D AttenburrOW, R Barrett, K Arkill, DB Colridge, CP Winlove (2007)Characterisation of mineralisation of bone and cartilage: X-ray diffraction and Ca and SrK alpha X-ray fluorescence microscopy, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS263(1)pp. 1-6
    NM Noor, MA Jusoh, AFA Razis, A Alawiah, DA Bradley (2015)Flat Ge-doped Optical Fibres for Food Irradiation Dosimetry, In: FA Rahman, Y ThianKhok, P YeongNan, L HorngSheng (eds.), NATIONAL PHYSICS CONFERENCE 2014 (PERFIK 2014)1657
    S Hashim, DA Bradley, N Peng, AT Ramli, H Wagiran (2010)The thermoluminescence response of oxygen-doped optical fibres subjected to photon and electron irradiations, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT619(1-3)pp. 291-294
    DA Bradley, MJ Farquharson, O Gundogdu, A Al-Ebraheem, EC Ismail, W Kaabar, O Bunk, F Pfeiffer, G Falkenberge, M Bailey (2010)Applications of condensed matter understanding to medical tissues and disease progression: Elemental analysis and structural integrity of tissue scaffolds, In: RADIATION PHYSICS AND CHEMISTRY79(2)pp. 162-175
    DJ Garrity, AJ De Rosa, DA Bradley, SE Jarman, PM Jenneson, SM Vincent (2010)Development of a prototype pipework scanning system based upon energy dispersive X-ray diffraction (EDXRD), In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT619(1-3)pp. 287-290
    DA Bradley, CJ Moger, CP Winlove (2007)Zn deposition at the bone-cartilage interface in equine articular cartilage, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT580(1)pp. 473-476
    DA Bradley, W Kaabar, O Gundogdu (2012)Elemental and structural studies at the bone-cartilage interface, In: AIP Conference Proceedings1423pp. 319-326

    The techniques μProton-Induced X-and γ-ray Emission, μ-PIXE and μ-PIGE, were used to investigate trace and essential element distributions in sections of normal and osteoarthritic (OA) human femoral head. μ-PIGE yielded 2-D mappings of Na and F while Ca, Z, P and S were mapped by μ-PIXE. The concentration of chondroitin sulphate supporting functionality in healthy cartilage is significantly reduced in OA samples. Localised Zn points to osteoblastic/osteoclastic activity at the bone-cartilage interface. Small-angle X-ray scattering applied to decalcified OA-affected tissue showed spatial alterations of collagen fibres of decreased axial periodicity compared to normal collagen type I.

    M Begum, AKMM Rahman, HA Abdul-Rashid, WSW Abdullah, NM Noor, MI Zulkifli, SZ Muhamad-Yasin, KA Mat-Sharif, N Tamchek, SNM Nawi, N Wahib, YM Amin, DA Bradley (2013)Thermoluminescence Response of Ge-doped Optical Fiber Dosimeters with Different Core Sizes, In: F Abdullah (eds.), 2013 IEEE 4TH INTERNATIONAL CONFERENCE ON PHOTONICS (ICP)pp. 290-292
    E Dalah, David Lloyd, D Bradley, A Nisbet (2009)Computational simulation of tumour hypoxia as applied to radiation therapy applications, In: IFMBE Proceedings25(1)pp. 64-66

    It has long been appreciated that hypoxia plays a significant role in tumour resistance to radiotherapy treatment, chemotherapy treatment and also in surgery. For present interests, it is noted that tumour radio-sensitivity increases with the increase of oxygen concentration across tumour regions. A theoretical representation of oxygen distribution in 2D vascular architecture using a reaction diffusion model enables relationships between tissue diffusivity, tissue metabolism, anatomical structure of blood vessels and oxygen gradients to be characterized quantitatively. We present a refinement to the work of Kelly and Brady (2006) and demonstrate the significant effect of the role of the venules supply on the microcirculation process at the intracellular level. With our representation of the two latter forces, the model is being developed to simulate the uptake of various PET reagents, such as 64Cu-ATSM, to demonstrate their potential use in radiation therapy treatment planning as an indicator of tumour hypoxic regions.

    AL Palmer, DA Bradley, A Nisbet (2015)Evaluation and mitigation of potential errors in radiochromic film dosimetry due to film curvature at scanning., In: J Appl Clin Med Phys16(2)pp. 5141-?

    This work considers a previously overlooked uncertainty present in film dosimetry which results from moderate curvature of films during the scanning process. Small film samples are particularly susceptible to film curling which may be undetected or deemed insignificant. In this study, we consider test cases with controlled induced curvature of film and with film raised horizontally above the scanner plate. We also evaluate the difference in scans of a film irradiated with a typical brachytherapy dose distribution with the film naturally curved and with the film held flat on the scanner. Typical naturally occurring curvature of film at scanning, giving rise to a maximum height 1 to 2 mm above the scan plane, may introduce dose errors of 1% to 4%, and considerably reduce gamma evaluation passing rates when comparing film-measured doses with treatment planning system-calculated dose distributions, a common application of film dosimetry in radiotherapy. The use of a triple-channel dosimetry algorithm appeared to mitigate the error due to film curvature compared to conventional single-channel film dosimetry. The change in pixel value and calibrated reported dose with film curling or height above the scanner plate may be due to variations in illumination characteristics, optical disturbances, or a Callier-type effect. There is a clear requirement for physically flat films at scanning to avoid the introduction of a substantial error source in film dosimetry. Particularly for small film samples, a compression glass plate above the film is recommended to ensure flat-film scanning. This effect has been overlooked to date in the literature.

    WL Dunn, CJ Solomon, KW Loschke, DA Bradley, WB Gilboy (2007)Ionizing photon methods for standoff bomb detection, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT580(1)pp. 778-781
    AS Siti Shafiqah, YM Amin, R Md Nor, N Tamchek, MS Khairul Anuar, HA Abdul Rashid, DA Bradley (2015)Properties of ge-doped silica preform by raman spectroscopy, In: ARPN Journal of Engineering and Applied Sciences10(15)pp. 6214-6218

    ©2006-2015 Asian Research Publishing Network (ARPN).In the present work, the structural modifications of Ge-doped silica preforms due to γ-irradiation at room temperature have been investigated using Raman spectroscopy. The MCVD fabricated preforms labelled as P1 and P2 are distinguishable by the oxidation and thermal history during the fabrication process, in which related to the oxygen bonding of SiO4 tetrahedral. From Raman analysis, the 480 cm-1(D1) and 609 cm-1(D2) peaks are the main network features of pure and doped silica glass, suggest the formation of defect centers in the preforms. The structural modifications of this defects centers are more sensitive in P2, due to the oxygen deficient state of the preform.

    F Mohamed, DA Bradley, CP Winlove (2006)Effects of ionizing radiation on extracellular matrix, In: Transactions of the American Nuclear Society95pp. 433-?
    F Mohamed, DA Bradley, CP Winlove (2007)Effects of ionizing radiation on extracellular matrix, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT580(1)pp. 566-569
    S M Jafari, N M Bates, T Jupp, S F Abdul Sani, A Nisbet, D Bradley (2016)Characterisation of commercial glass beads as TLDs in radiotherapy, In: Radiation Physics and Chemistry137pp. pp181-186 Elsevier
    Shakardokht Jafari, G. Distefano, J. Lee, C. Gouldstone, H. Mayles, D. A. Bradley, N. M. Spyrou, A. Nisbet, C. H. Clark (2015)Feasibility of using glass bead TLDs for a postal dosimetry audit of MV radiotherapy photon beams, In: Proceedings of the 8th UK Radiation Oncology Conference (UKRO) Varian Medical Systems, Inc.
    RP Hugtenburg, F Saeedi, DA Bradley (2007)Modeling dose response to synchrotron X-rays in solid-state and biological systems, In: RADIATION EFFECTS AND DEFECTS IN SOLIDS162(10-12)pp. 765-769
    S Jafari, C Gouldstone, P H G Sharpe, D A Bradley, C H Clark, A Nisbet, N M Spyrou (2018)Characterisation of Glass Beads for Radiotherapy Dosimetry, In: Proceedings of the 7th United Kingdom & Republic of Ireland Postgraduate Conference in Biomedical Engineering and Medical Physicspp. p15-15

    Examinations have been made of a low cost commercially available material which is potentially useful as a dosimeter in radiotherapy. An investigation of the thermoluminescent (TL) yield and electron paramagnetic resonance (EPR) signal was performed by irradiating acid-washed glass jewellery beads to MV photons using a medical linear-accelerator and 60Co gamma rays. For comparison, irradiation exposures were also carried out on 5 mm length of Ge-doped optical fibres that have been widely investigated for their TL properties [1]. The dose response was linear for the investigated dose range of 1 to 2500 cGy, with an R2 correlation coefficient of > 0.999 and reproducibility of 1.7%. The results suggest the potential for use of glass beads as TL dosimeters in radiotherapy.

    Anton Johannes Veldhuis, Jane Glover, David Bradley, Kourosh Behzadian, Alma Lopez-Aviles, Julian Cottee, Clare Downing, John Ingram, Matthew Leach, Raziyeh Farmani, David Butler, Andy Pike, Lisa De Propris, Laura Purvis, Pamela Robinson, Aidong Yang (2017)Re-distributed manufacturing and the food-water-energy nexus: Opportunities and challenges, In: Production Planning & Control Taylor & Francis

    Addressing the intersection of two important emerging research areas, re-distributed manufacturing (RDM) and the food-energy-water (FEW) nexus, this work combines insights from engineering, business and policy perspectives and explores opportunities and challenges towards a more localised and sustainable food system. Analysis centred on two specific food products, namely bread and tomato paste reveals that the feasibility and potential of RDM vary with the type of food product and the supply chain (SC) components. Physically, energy efficiency, water consumption and reduction of waste and carbon footprint may be affected by scale and location of production activities and potentials of industrial symbiosis. From the business perspective, novel products, new markets and new business models are expected in order for food RDM to penetrate within the established food industry. Studies on policies, through the lens of public procurement, call for solid evidence of envisioned environmental, social and economic benefits of a more localised food system. An initial integrated framework is proposed for understanding and assessing food RDM and the FEW nexus

    W Kaabar, O Gundogdu, M Tzaphlidou, M Janousch, D Attenburrow, DA Bradley (2008)Investigation of essential element distribution in the equine metacarpophalangeal joint using a synchrotron radiation micro x-ray fluorescence technique, In: HB Senin, G Carini, J Abdullah, DA Bradley (eds.), CURRENT ISSUES OF PHYSICS IN MALAYSIA1017pp. 18-24
    D Malain, PH Regan, DA Bradley, M Matthews, T Santawamaitre, HA Al-Sulaiti (2010)Measurements of NORM in beach sand samples along the Andaman coast of Thailand after the 2004 tsunami, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT619(1-3)pp. 441-445
    E Daar, E Woods, JL Keddie, A Nisbet, DA Bradley (2010)Effect of penetrating ionising radiation on the mechanical properties of pericardium, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT619(1-3)pp. 356-360