Analysis of prostate seed loading for permanent implants

The goal of radioactive seed implantation in prostate cancer is to treat th e tumor to the necessary dose while minimizing the dose to adjacent normal structures. The uniform and peripheral loading schemes used in the past hav e serious limitations. However, with the availability of three-dimensional treatment-planning systems, it has become possible to do custom volume load ing based on volumetric ultrasound imaging of the gland. As a result, the d ose distributions are more uniform, and the doses to the urethra and rectum are maintained in a safe range.