ResearchSummary of MASc Thesis Research: "Real-Time Dosimetry for Prostate Brachytherapy Using TRUS and Fluoroscopy"Prostate brachytherapy is frequently used to treat low-risk prostate cancer. Transrectal ultrasound (TRUS) is used to guide needles and permanently implant between 80 and 150 small radioactive seeds in the prostate. Because of inaccuracies in needle placement and intraoperative prostate shifting and swelling, there is a need to provide accurate real-time dosimetric feedback. This feedback will allow radiation oncologists to intraoperatively modify the planned seed locations (i.e. interactive planning) ensuring the prostate receives sufficient radiation to destroy cancerous cells.We are developing a new approach for computing real-time dosimetry (RTD) for prostate brachytherapy that easily fits into the current clinical procedure practiced at the Vancouver Cancer Clinic. A single fluoroscopic image of the TRUS probe is used to register the fluoroscopic and TRUS images. As is current procedure, the radiation oncologist inserts each needle locating its tip in the TRUS image. From the tip location and the entry point of the needle, a needle path is computed by interpolating from the needle base to the tip. Periodically, a fluoroscopic image is taken to determine the (x,z)-coordinates of the seeds. Using these coordinates and the needle path, the y-coordinates of the seeds are computed. Knowing the coordinates of each seed allows dosimetry to be displayed to the radiation oncologist, so the preoperative plan can be intraoperatively modified to reflect inaccuracies in seed placement and intraoperative seed motion. |