A CT or MRI scan is used to pinpoint the exact location of the tumor in the brain. High-energy radiation beams are trained on the tumor from different angles. The radiation destroys the tumor.
Radiosurgery is called "surgery" because it is a one-session treatment with a similar result as an open surgical procedure. Gamma knife is one type of radiosurgery. The advantage of radiosurgery over open surgery is it has fewer complications and the recovery time is much shorter.