Stereotactic radiation therapy or radiosurgery is a specialized form of external beam therapy that uses sophisticated computerized imaging to precisely target a narrow X-ray beam. For this technique, multiple highly focused radiation beams are delivered from multiple directions with pinpoint accuracy. This form of treatment is often used for tumors or other growths within the skull, including arterio-venous malformations and acoustic neuromas. It may also be used for cancer or non-cancerous growths along the spine or even in other parts of the body.

Radiosurgery generally implies a single high dose or just a few high dose treatments. These treatments may be administered with a conventional medical linear accelerator or with a specially designed linear accelerator called the "CyberKnife."