Gamma knife

A type of radiosurgery (radiation therapy) machine that acts by focusing low-dosage gamma radiation from many sources on a precise target. Areas adjacent to the target receive only slight doses of radiation, while the target gets the full intensity. The gamma knife may be used to treat brain tumors, metastatic tumors in the brain (from sites such as the breast, lung, and skin), vascular malformations of the brain, acoustic neuromas (a tumor of the hearing nerve); meningiomas (tumors on the protective layers of the brain); trigeminal neuralgia causing severe facial pain; and temporal lobe epilepsy.