Introduction: Radiation dose to erectile tissue may contribute to erectile dysfunction (ED) in the treatment of prostate cancer. This report for the first time studies the ability to limit dose to erectile tissue using IMRT. Methods: Twenty-three consecutive men with palpable Tl-3 NX or NO MO prostate cancer received IMRT alone. The median prescribed prostate dose was 74Gy to the PTY The volumes of the prostate, penile bulb (PB) & corporal bodies (CB) were defined by CT/MRI prior to treatment. Three plans with different PB and CB constraints were generated for each patient: no dose constraint, 20 &r 15Gy (intermediate dose) and 15 & 7Gy (low dose). All plans were normalized such that the prostate D95 received at least 100% of the prescribed dose. For each plan, the ability to meet prostate dose homogeneity criteria (PHC; prostate Dmax < 120.5% prescribed dose) & rectal tolerance DVH criteria (RTC; rectal V40Gy < 35% & V65Gy < 17%) was determined. For each plan the D90.V50 & V75 were determined for both the PB & CB. Results: The median PB D90, V50 & V75 for plans with no dose, intermediate dose and low dose restriction were: 20.8Gy, 33.8%, 9.9%; S.OGy, 1.7%, 0%; & 7.1Gy, 0.1%, 0%, respectively. The median CB D90.V50 & V75 for plans with no dose, intermediate dose & low dose restriction were: 10.2Gy, 3.8%, 0%; 6.0Gy, 0%, 0%; & 4.9Gy, 0%, 0%, respectively. Overall differences in the median D90, V50 & V100 between groups were significant for both the PB & CB (P < 0.0001). All no dose restriction plans met PHC &r RTC. Twenty-one intermediate dose plans met both PHC &r RTC. Eighteen low dose plans met PHC and 19 met RTC. There was no significant difference in the median number of beam segments for the 3 groups (51, 55 & 53; P = 0.8) Conclusions: It is possible to limit dose to erectile tissues with 1MRT usually by s 50% without compromising PHC, RTC or treatment duration. Clinical correlation between dose & ED requires further study.
ASJC Scopus subject areas
- Cancer Research