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PURPOSE: To quantitatively evaluate through automated simulations the clinical significance of potential HDR prostate brachytherapy (HDRPB) physics errors selected from our internal failure-modes and effect analysis (FMEA). METHODS: A list of failure modes was compiled and scored independently by 8 brachytherapy physicists on a one-to-ten scale for severity (S), occurrence (O), and detectability (D), with risk priority number (RPN) = SxOxD. Variability of RPNs across observers (standard deviation / average) was calculated. Six idealized HDRPB plans were generated, and error simulations were performed: single (N=1,722) and systematic (N=126) catheter shifts (craniocaudal; −1cm:1cm); single catheter digitization errors (tip and connector needle-tips displaced independently in random directions; 0.1cm:0.5cm; N=44,318); and swaps (two catheters swapped during digitization or connection; N=528). The deviations due to each error in Prostate D90%, Urethra D20% and Rectum D1cm(3) were analyzed using two thresholds: 5–20% (possible clinical impact) and >20% (potentially reportable events). RESULTS: Twenty-nine relevant failure modes were described. Overall, RPNs ranged from 6 to 108 (average ± 1 standard deviation, 46±23), with responder variability ranging from 19% to 184% (average 75%±30%). Potentially reportable events were observed in the simulations for systematic shifts >0.4cm for prostate and digitization errors >0.3cm for the urethra and >0.4cm for rectum. Possible clinical impact was observed for catheter swaps (all organs), systematic shifts >0.2cm for prostate and >0.4cm for rectum, and digitization errors >0.2cm for prostate and >0.1cm for urethra and rectum. CONCLUSION: A high variability in RPN scores was observed. Systematic simulations can provide insight in the severity scoring of multiple failure modes, supplementing typical FMEA approaches.

To report long-term survival and toxicity outcomes with the use of high-dose intensity modulated radiation therapy (IMRT) to 86.4 Gy for patients with localized prostate cancer.Between August 1997 and December 2008, 1002 patients were treated to a dose of 86.4 Gy using a 5-7 field IMRT technique. Patients were stratified by prognostic risk group based on National Comprehensive Cancer Network risk classification criteria. A total of 587 patients (59%) were treated with neoadjuvant and concurrent androgen deprivation therapy. The median follow-up for the entire cohort was 5.5 years (range, 1-14 years).For low-, intermediate-, and high-risk groups, 7-year biochemical relapse-free survival outcomes were 98.8%, 85.6%, and 67.9%, respectively (P.001), and distant metastasis-free survival rates were 99.4%, 94.1%, and 82.0% (P.001), respectively. On multivariate analysis, T stage (P.001), Gleason score (P.001), and50% of initial biopsy positive core (P=.001) were predictive for distant mestastases. No prostate cancer-related deaths were observed in the low-risk group. The 7-year prostate cancer-specific mortality (PCSM) rates, using competing risk analysis for intermediate- and high-risk groups, were 3.3% and 8.1%, respectively (P=.008). On multivariate analysis, Gleason score (P=.004), percentage of biopsy core positivity (P=.003), and T-stage (P=.033) were predictive for PCSM. Actuarial 7-year grade 2 or higher late gastrointestinal and genitourinary toxicities were 4.4% and 21.1%, respectively. Late grade 3 gastrointestinal and genitourinary toxicity was experienced by 7 patients (0.7%) and 22 patients (2.2%), respectively. Of the 427 men with full potency at baseline, 317 men (74%) retained sexual function at time of last follow-up.This study represents the largest cohort of patients treated with high-dose radiation to 86.4 Gy, using IMRT for localized prostate cancer, with the longest follow-up to date. Our findings indicate that this treatment results in excellent clinical outcomes with acceptable toxicity.