For many patients with prostate cancer, physicians at Virginia Mason use an advanced technique known as real-time dosimetry prostate seed brachytherapy. This technique allows the most precise placement of radioactive seeds into the prostate with millimeter accuracy. The traditional pre-plan method requires a preoperative ultrasound study in which the patient's position must be matched exactly at the time of the implant. Matching this position in the operating room is often difficult and can result in inaccurate placement of seeds. The real-time technique avoids this problem by using a computer system in the operating room to map the prostate gland. In addition, it also gives the physician the ability to precisely track the position of each seed as it is placed, ensuring proper radiation dose within the prostate. Equally important, this technique helps physicians avoid the placement of seeds near normal tissues such as the bladder, urethra, and rectum, thus minimizing toxicity. It is the most focused and conformal radiation treatment for prostate cancer.