The development of a silicon detector quality assurance system for high dose rate brachytherapy

Prostate cancer was the most commonly diagnosed cancer in males in Australia in 2012, with over 18,560 cases. It is estimated that 1 in 9 men in Australia will develop prostate cancer at one time in their lives, with the risk of being diagnosed by age of 85 close to 1 in 5. In 2011 – 2012, over 2000 prostate cancer patients were treated by radiation therapy. Brachytherapy accounted for 62% of radiotherapy procedures in prostate cancer-related hospitalisations over this period. High Dose Rate (HDR) brachytherapy is the temporary insertion of a radioactive source directly in or close to a tumour. Small, hollow catheters are inserted into the treatment region and a remote afterloader is used to drive the highly active radiation source through each catheter to deliver dose. The remote afterloader fully controls the placement of the source, by driving it to planned points inside of each catheter, for an amount of time determined to deliver the planned dose to the tumour. As there can be complications resulting from an incorrect treatment of HDR brachytherapy, it is essential that methods and instrumentation for quality assurance (QA) are available to medical physicists. Direct and accurate verification the treatment plan delivery and the functionality of the remote afterloader are of paramount importance in ensuring appropriate treatment. Currently, there are no comprehensive QA solutions available for HDR brachytherapy. This aim of this thesis is to develop a novel HDR QA system, the Magic Plate , using an 11×11 array of silicon epitaxial diodes, fast readout electronics and a software tool kit, capable of triangulating the HDR source position in three-dimensions. A HDR brachytherapy specialised casing, the Magic Phantom , was designed and tested for pretreatment delivery confirmation of any HDR brachytherapy plan. A feasibility study was performed to assess the Magic Plate in real-time verification during patient treatment