Gamma knife is a computerized way of delivering high dose radiation
to a tumor without much of the radiation hurting the brain.
For benign tumors like meningiomas and acoustic neuromas, tumors can be controlled for 10 to 20years and maybe more. Tumors have to be smaller than 3 cm (1 1/2 in) in diameter. Gamma knife can also slow the growth of malignant brain tumors.