Purpose: To evaluate adaptive planning for permanent prostate brachytherapy and to identify the prostate regions that needed adaptation. Methods and materials: After the implantation of stranded seeds, using real-time intraoperative planning, a transrectal ultrasound (TRUS)-scan was obtained and contoured. The positions of seeds were determined on a C-arm cone-beam computed tomography (CBCT)-scan. The CBCT-scan was registered to the TRUS-scan using fiducial gold markers. If dose coverage on the combined imagedataset was inadequate, an intraoperative adaptation was performed by placing remedial seeds. CBCT-based intraoperative dosimetry was analyzed for the prostate (D 90 , V 100 , and V 150 ) and the urethra (D 30 ). The effects of the adaptive dosimetry procedure for Day 30 were separately assessed. Results: We analyzed 1266 patients. In 17.4% of the procedures, an adaptation was performed. Without the dose contribution of the adaptation Day 30 V 100 would be < 95% for half of this group. On Day 0, the increase due to the adaptation was 11.8 AE 7.2% (1SD) for D 90 and 9.0 AE 6.4% for V 100 . On Day 30, we observed an increase in D 90 of 12.3 AE 6.0% and in V 100 of 4.2 AE 4.3%. For the total group, a D 90 of 119.6 AE 9.1% and V 100 of 97.7 AE 2.5% was achieved. Most remedial seeds were placed anteriorly near the base of the prostate. Conclusion: CBCT-based adaptive planning enables identification of implants needing adaptation and improves prostate dose coverage. Adaptations were predominantly performed near the anterior base of the prostate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.