Three-dimensional treatment planning considerations for prostate cancer.

Over 300 treatment plans for a total of eight disease sites based on 3-D treatment planning considerations utilizing serial CT delineated target volumes were generated by four institutions as part of an NCI supported contract to both assess the current state-of-the-art capabilities and point directions for future efforts. Two patients with stage C prostate cancer were evaluated with protocol plans which required treatment of the prostate to 70 Gy and the pelvic lymph nodes to 46 Gy. When full 3-D target definition and multiple beam arrangements were employed, all institutions were able to submit plans which scored higher on tumor coverage and had lower normal tissue complication scores compared to traditional plans. The 3-D plans using standard beam arrangements, however, were often rated as highly as the 3-D unconstrained plans due to the multiple beam arrangements already selected to optimize standard plans at most institutions. For this site, heterogeneity corrections, beam energy changes and changes in CT number did not substantially change plan scores.