Master of Philosophy (Medical Radiation Physics)
School of Physics
Vohradsky, James E., Study in the Feasibility of Silicon and Diamond Microdosimetry use in Boron Neutron Capture Therapy, Master of Philosophy (Medical Radiation Physics) thesis, School of Physics, University of Wollongong, 2017. https://ro.uow.edu.au/theses1/94
The shift from reactor to accelerator based neutron production has created a renewed interested in Boron Neutron Capture Therapy (BNCT). This method is typically used to treat inoperable brain tumours (glioblastoma) that cannot be treated by traditional forms of radiotherapy or chemotherapy. BNCT is reliant upon the favourable uptake of boron 10 by tumour cells along with the interaction with neutrons to produce high LET fragments (He and Li nuclei) that deposit energy locally within the tumour site. As with any radiation based treatment, Quality Assurance (QA) is crucial in terms of patient safety.
This study extends previous work in proton and Heavy Ion Therapy and concerns the application of solid state microdosimetry in the field of BNCT. The project has been performed by means of Monte Carlo simulations. Geant4 was used to model and optimise the design of silicon on insulator and diamond based microdosimeters. Detector optimisation in this context, pertains to the geometry and materials (i.e., sensitive volume size and probability of neutron activation) to be used in the construction of detectors.
The study has shown conclusively that the currently available microdosimeters do not pose any radiation protection risk with the typical exposure times of BNCT.
Whilst the materials currently used in the fabrication of silicon and diamond based microdosimeters are appropriate, there are changes with respect to the sensitive volume thickness that must be addressed. Lastly, the applicability of previously determined correction factors to convert microdosimetric spectra from silicon/diamond to water was evaluated within the context of BNCT.