Isodose distribution in an axial CT plane after 125I brachytherapy implantation with a RBI. The prescribed dose to the prostate (red) was 145 Gy (green). The high-dose region >120% (yellow) and the low-dose region <40% (purple) with minimal overlap in the rectum (dark-blue). Abbreviation: RBI = Rectal Balloon Implant. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)