Stereotactic radiosurgery is an advanced form of radiation therapy. In contrast to other radiation treatments, stereotactic radiosurgery targets small areas with highly focused, intense beams of radiation. As a result, healthy surrounding tissues receive less radiation. Over the past 60-plus years, different stereotactic radiosurgery delivery systems have been developed. These systems vary in how radiation is delivered and how the patient is positioned for the treatment. Gamma Knife is one of these treatments, and was developed specifically to treat conditions of the brain and head.