Grant: Doctoral Award - Frederick Banting and Charles Best Canada Graduate Scholarships

Brachytherapy, the insertion of encapsulated radioactive material directly into the cancer, is a popular treatment option for prostate cancer. Permanent prostate brachytherapy is an out-patient operative procedure where a physician inserts radioactive sources (< 1mm diameter) into the prostate via thin needles under the guidance of a template and an ultrasound (US) probe. The standard radiation dose prescription to the prostate is 140 Gy. However, the spatial locations of the implanted seeds after the probe is removed are expected to differ from their intended positions (when the probe is in place during the implantation). This is cased by the pressure from the US probe and results in a lower dose delivered to the patient. To compensate, the physician on purpose over-estimates to delivery 180 Gy. The actual dose on average reduces to the desired 140 Gy. However, the planned target dose of 180 Gy is only an estimate and patients can receive anywhere between 100 to 180 Gy, reflecting the lack of knowledge affecting the reduction in dose. It is essential that the prostate receives the prescribed dose of 140 Gy. Insufficient dose decreases the chances of eliminating the tumour while too much dose results in unnecessary side-effects. The proposed project aims to study and model the effect of the US probe on the prostate shape. Using Magnetic Resonance (MR) images, ultrasound images, and information on the pressures exerted by the probe, the model will calculate the changes in prostate shape and seed positions when the probe is removed. We will then build an experimental apparatus to simulate these effects and test the computer model. Once this is successful, we can test the model using real patient data. With a suitable model, we can create a "preview" of the seed positions and the dose to the prostate. We can then modify the seed positions to correct for the effects of the US probe, delivering 140 Gy to each and every patient.