Efficacy of prostate stabilizing techniques during brachytherapy procedure

During the prostate brachytherapy procedure, multiple needles are inserted into the prostate and radioactive seeds are deposited. Stabilizing needles are first inserted to provide some rigidity and support to the prostate, ideally this will provide better seed placement and an overall improved treatment. However, there is much speculation regarding the effectiveness of using regular brachytherapy needles as stabilizers. In this study, we explored the efficacy of (1) two types of needles--18 gauge brachytherapy needle vs. 18 gauge hooked needle; and (2) parallel vs. angulated needle configurations to stabilize the prostate. Prostate phantom movement and needle insertion progression were imaged using ultrasound (US). The recorded images were analyzed and prostate displacement was computed from images using implanted artifacts. Experimentation allowed us to further understand the mechanics behind prostate stabilization. We observed superior stabilization by the hooked needles compared to the regular brachytherapy needles (more than 40% for parallel stabilization). Prostate movement was also reduced significantly when regular brachytherapy needles were in an angulated configuration as compared to the parallel configuration (approximately 40%). When the hooked needles were angled for stabilization, further improvement in decreased displacement was observed. In general, for convenience of dosimetric planning, all needles are desired to be in parallel and in this case, hooked needles are better suited to improve stabilization of the prostate. On the other hand, both regular and hooked needles appear to be equally effective in reducing prostate movement when they are in angulated configurations, which will be useful in robotic permanent seed implantation (PSI).