Stereotactic Radiosurgery was initially defined as a single-faction technique using stereotactic principles for targeting and treating intracranial lesions through the use of noncoplanar beams. The techniques on which radiosurgery is founded have been applied to fractionated treatments termed stereotactic radiotherapy. SRT is an advanced and modernized form of radiation therapy that uses high energy x-ray beams to shrink or control the growth of a tumor or abnormal cells by either killing the cells directly or by disrupting their ability to grow.

The type of radiation is the same for both conventional radiation therapy and SRT, however, SRT enables radiation oncologists to deliver high-dose radiation to a small focused area. Using SRT, radiation oncologists are better able to exclude the surrounding normal tissues or organs than with conventional radiotherapy. This specialized form of radiation treatment involves a team of specialists including neurosurgeons, radiation oncologists, radiologists, radiation physicists, radiation therapists, and nurses.

Although very similar therapies, SRS delivers a large dose of radiation on a single day, while SRT has a fractionated treatment schedule. With SRT, treatment will span multiple days. While the total dose with SRT

may be larger than in SRS, in any single day, patients undergoing SRT receive a smaller radiation dose. Cranial SRS or SRT is now the standard of care for benign and malignant brain tumors and numerous benign conditions including arteriovenous fistulas, trigeminal neuralgia, and other pain conditions, and movement disorders such as Parkinson’s disease and epilepsy. More recently, SRS and SRT are also being used extra cranially, namely for locations outside the brain.