Year

2014

Degree Name

Master of Science - Research

Department

School of Physics

Abstract

This project investigates the optimisation of the detector packing required for the electromagnetic screening of the in vivo urethral mini-dosimeter, developed by the Centre for Medical Radiation Physics (CMRP), through Monte Carlo simulations. Monte Carlo simulations were performed for the device detector within a liquid water phantom to optimise the geometry of the device encapsulation, with a priority on angular isotropy and depth-dose response.

Monte Carlo simulations were performed to determine the effect of the depletion region depth on angular isotropy and depth dose response of the detector. The use of a thin, grounded, aluminium shield within the device encapsulation was found to not substantially perturb the response of the detector within the device. The normalised depth-dose response of the device was within ±2.0% of the simulated doses in water, up to 35mm and within ±5.3% of the simulated doses in water, up to 50mm from a brachytherapy seed, for all thicknesses of aluminium shielding. The angular isotropy response distribution was within ±3.8% for 20μm of aluminium shielding, ±3.0% for 50μm of aluminium shielding and ±2.5% for 100μm of aluminium shielding. The depletion depth was found to have an effect on the angular isotropy and depth dose response of the device, necessitating full depletion for optimal operation. The urethral mini dosimetry system will provide real time monitoring of the urethral dose during low dose rate prostate brachytherapy, allowing additional quality assurance of the treatment modality.

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