Poster — Thur Eve — 63: Planning and Phantom Study of Oblique Needle Based Low Dose Rate Prostate Brachytherapy (LDRPB) Using 3D Trans-Rectal Ultrasound (TRUS) and Robotic Assistance



The purpose of this study was to create a phantom to validate the Low Dose Rate Prostate Brachytherapy (LDRPB) plans using oblique (angled) needles delivered using robotic guidance in overcoming pubic arch interference for large prostates. Five patient 3D Trans-rectal Ultra Sound (TRUS) images were selected. The images were required to show a maximum pubic arch interference of <= 1 cm and prostate volume of < 50 cc. The prostate contours were artificially enlarged to 60 cc while keeping the pubic arches constant. The following three different types of plans were manually created for each 60 cc prostate: parallel needle template based, parallel needle non template based, and oblique needle non template based. One sided t-tests between the three different types of plans were computed for DVH indices recommended by ESTRO for LDRPB. At the 1% significance level, a better DVH index for each organ (PTV, Urethra, and Rectum) was observed for oblique plans compared to the other two techniques. The feasibility of robot and 3D TRUS guided delivery of oblique plans are being tested in a phantom study. We created a phantom based on one of the 60 cc prostate contours with a plastic plate simulating pubic arch interference. Robot and 3D TRUS guided delivery of an oblique plan will be delivered. Results of CT images of the delivered seeds will be compared to that of the planned position, validating the feasibility of delivering oblique plans.