Modelling a Compact Compton Camera from HEXITEC Detectors for Radiation Therapy Applications

The detection of prompt gamma particles produced inside the patient’s body during radiation treatments (proton beam therapy, boron neutron capture therapy, among others) has been recognised as a promising tool for performing in-vivo verification studies. To achieve this, it is essential to obtain information about the production origin of such particles within the patient, as they are released from de-excitation processes in tissue nuclei during treatment. Compton cameras have the potential for accurate directional radiation detection with high count rates as no physical collimation is needed. However, current Compton camera models face challenges regarding both hardware in terms of portability and software in terms of useful event selection for noise reduction. The present work studies the feasibility of the High Energy X-ray Imaging Technology (HEXITEC) detector, which has a pixellated, energy resolved Cadmium Zinc Telluride sensor, as the elementary unit of a Compton camera. The study sets out to determine if the increased spectral and spatial information of the sensor can be exploited for this application, while maintaining a compact, portable detection system. This involves building a flexible Geant4 model where multiple HEXITEC modules are aligned pointing towards a prompt gamma source. The optimal geometric parameters including sensor placements, thicknesses and inter-layer spacing will be presented and discussed for experimental trials, along with an analysis on the effects of the back layers of the detector and the performance of the Stochastic Origin Ensemble as the reconstruction algorithm. Overall, this study represents a significant step towards a novel application of the HEXITEC detector for the development of a highly optimised, compact Compton camera system.