Optimisation of the End-To-End Phantom for Real-time High Dose Rate Prostate Brachytherapy Verification

High dose rate (HDR) brachytherapy is a form of close range radiotherapy whereby dose is delivered by means of an internal radiation source. By doing so, a high level of dose con-formity and accuracy can be achieved. However, due to the high source activity coupled with the close proximity of radio-sensitive organs such as the rectum, bladder and urethra, there exists the potential of incorrect dose delivery; the irradiation of these organs may con-sequently lead to post-treatment complications. As a result, the need for accurate forms of quality assurance methodology which can verify different aspects of the treatment delivery is paramount. These methodologies must be able to perform real-time dose analysis to monitor crucial organ exposure as well as accurately localise the HDR source within space to verify its position according to the treatment plan. An End-to-end Phantom was developed with anatomically correct Gel Prostate phantoms to create an anthropomorphic representation of the clinical environment. This allowed the testing of clinically relevant treatment plans on the MP987 detector system to test its source localisation capabilities. It was shown that when comparing to the TPS defined dwell po-sitions, the system was able to determine positions on average to within (3.69±0.14)mm,(3.70±0.15)mm, (3.53±0.12)mm and (0.30±0.06)s for the x, y, z and t coordinates respec-tively.