CyberKnife Stereotactic Radiosurgery for Low and Intermediate Risk Prostate Cancer

The purpose of this study is to determine the side effects and how effective CyberKnife stereotactic ablative body radiation (SABR) is in patients with prostate cancer. The CyberKnife system is a new type of radiation machine that uses a special system to precisely focus large doses of x-rays on the tumor. The device is designed to concentrate large doses of radiation onto the tumor so that injury from radiation to the nearby normal tissue will be minimal. The purpose of this evaluation is to see if this treatment will help patients with low to intermediate risk prostate cancer and to evaluate the effect of this treatment on the patients' quality of life over time.