Prostate brachytherapy intraoperative dosimetry using a combination of radiographic seed localization with a C-arm and deformed ultrasound prostate contours.

PURPOSE: The purpose of the study was to assess the feasibility of performing intraoperative dosimetry for permanent prostate brachytherapy by combining transrectal ultrasound (TRUS) and fluoroscopy/cone beam CT [CBCT] images and accounting for the effect of prostate deformation. METHODS AND MATERIALS: 13 patients underwent TRUS and multiview two-dimensional fluoroscopic imaging partway through the implant, as well as repeat fluoroscopic imaging with the TRUS probe inserted and retracted, and finally three-dimensional CBCT imaging at the end of the implant. The locations of all the implanted seeds were obtained from the fluoroscopy/CBCT images and were registered to prostate contours delineated on the TRUS images based on a common subset of seeds identified on both image sets. Prostate contours were also deformed, using a finite-element model, to take into account the effect of the TRUS probe pressure. Prostate dosimetry parameters were obtained for fluoroscopic and CBCT-dosimetry approaches and compared with the standard-of-care Day-0 postimplant CT dosimetry. RESULTS: High linear correlation (R2 > 0.8) was observed in the measured values of prostate D90%, V100%, and V150%, between the two intraoperative dosimetry approaches. The prostate D90% and V100% obtained from intraoperative dosimetry methods were in agreement with the postimplant CT dosimetry. Only the prostate V150% was on average 4.1% (p-value <0.05) higher in the CBCT-dosimetry approach and 6.7% (p-value <0.05) higher in postimplant CT dosimetry compared with the fluoroscopic dosimetry approach. Deformation of the prostate by the ultrasound probe appeared to have a minimal effect on prostate dosimetry. CONCLUSIONS: The results of this study have shown that both of the proposed dosimetric evaluation approaches have potential for real-time intraoperative dosimetry.

Population-based 10-year event-free survival after radical prostatectomy for patients with prostate cancer in British Columbia.

INTRODUCTION: We determined (1) the 10-year survival outcomes after radical treatment of prostate cancer and (2) the 10-year event-free survival following radical prostatectomy (RP) at a population-level in British Columbia (BC), Canada. METHODS: We identified all men with a new diagnosis of prostate cancer in BC between 1999 and 2000. Those treated with RP, external beam radiotherapy (EBRT) or brachytherapy (BT) were identified. Overall survival, and prostate cancer specific survival (PCSS) were calculated from diagnosis using the Kaplan-Meier method. For those men treated with RP, we calculated the 10-year event-free survival (freedom from salvage EBRT or androgen ablation, or death from prostate cancer). Reasons for initiating androgen therapy were unknown and may include symptomatic metastatic disease or asymptomatic biochemical recurrence. An important limitation was the absence of prostate-specific antigen data for staging or follow-up. RESULTS: Among 6028 incident cases, RP was the curative-intent treatment within 1 year in 1360 (22.6%) patients, EBRT in 1367 (22.7%), and BT in 357 (5.9%). The 10-year PCSS was 98% for RP, 95% for EBRT and 98% for BT (log rank p < 0.0001). The 10-year overall survival was 87%. The 10-year event-free survival for those treated with RP was 79% and varied with Gleason grade: 87%, 74%, and 52% for Gleason 2-6, 7, and 8-10, respectively (p < 0.0001). CONCLUSIONS: This population-based study provides outcomes which can inform patient decision-making and provide a benchmark to which other therapies can be compared. Event-free rates for patients treated with RP vary with Gleason score. There is room for improvement in the outcomes of patients with high Gleason score treated with RP.