Trace Elements in the Body

Determination of trace element concentrations in biological tissues using neutrons and protons as probes for instrumental neutron activation analysis (INAA) with the isotopic neutron cyclic irradiation facility at the Imperial College Reactor Centre and for proton induced X-ray emission (PIXE) analysis at the University's Ion Beam Analysis (IBA) accelerator facilities provides the means for studying, for example, metabolism and pathology in diseases, in biomedical and environmental problems, proteins and metalloenzymes.  

Hydrophilic Phantoms

The group is developing "phantoms" made of tissue equivalent hydrophilic materials to represent various parts of the body, including breast and head for a number of imaging modalities and probes.  The material must accurately reproduce the response of tissue to the probe, so that the "phantoms" can be used for calibration of diagnostic and therapy equipment and for quality assurance.  Interest in these phantoms arises from our research in the characterisation of high energy electron and photon beams from medical linear accelerators used in therapy.  Initial theoretical modelling of the photon beam spectra was in collaboration with the National Physical Laboratory (NPL); experimental verification of the photon spectra and neutron spectra produced through photodisintegration reactions is in collaboration with the King Faisal Specialist Hospital and Research Centre, Saudi Arabia, the Mid-Kent Oncology Centre, Maidstone and the Walsgrave Hospital, Coventry.

X-ray Computer Tomography

X-ray tomography is conducted in a variety of unique modalities.  High spatial resolution imaging is performed down to 5 micrometres on a micro-focus tube cone-beam tomographic scanner.  Low-dose tomographic imaging is also conducted for the study of living organisms such as plants which are radiation sensitive.  Diffraction CT is used to characterise materials using a 2D detector and a collimated beam from a mono-chromatic X-ray source.   High temporal resolution CT (real-time tomography) is also used to image rapidly changing media such as multi-phase flow in pipes.  The group has excellent radiation imaging laboratories equipped with various X-ray tubes from 50 kV to 200 kV peak energy, including a Hamamatsu micro-focus tube.  We have wide experience in the use and characterisation of digital X-ray imaging sensors, and our laboratory is equipped with a state of the art amorphous silicon flat panel imager, various CMOS/scintillator flat panels, and image intensifiers.  We can also calibrate our X-ray beams to provide a specific dose rate, using a calibrated ion chamber.

Monte Carlo Radiation Simulations

GEANT4, EGS4, MCNP4C and other Monte Carlo codes are used to model a number of different radiation transportation problems.  Detectors have been modelled and characterised, as have a number of different radiation-dose problems.  Exotic particles such as cosmic-ray muons have also been modelled to explore their possible use in macro-scale tomographic imaging of large industrial structures.

Please contact David Bradley for further information about medical physics research at Surrey.