radiosurgery

n. (Medicine) destruction of diseased tissue by directing concentrated beams of radiation at the tissue (rather than physically cutting away the tissue through traditional surgery)

Radiosurgery is a medical procedure which allows non-invasive brain surgery, i.e., without actually opening the skull, by means of directed beams of ionizing radiation. It is a relatively recent technique (1951), which is used to destroy, by means of a precise dosage of radiation, intracranial tumors and other lesions that could be otherwise inaccessible or inadequate for open surgery. There are many nervous diseases for which conventional surgical treatment is difficult or has many deleterious consequences for the patient, due to arteries, nerves, and other vital structures being damaged.
See more at Wikipedia.org...

Radiosurgery /ra·dio·sur·gery/ surgery in which tissue destruction is performed by means of ionizing radiation rather than by surgical incision. [more]Radiosurgery - Community and Resources

A radiation therapy technique that delivers radiation directly to the tumor while sparing the healthy tissue. Also called radiation surgery and stereotactic external beam irradiation.