Radiosurgery means delivery of a single dose of precisely directed ionizing radiation to a small volume of intracranial tissue without opening of the skull after the stereotactic localisation of the preselected target. Leksell gamma knife is a device enabling to deliver focused radiation toward the intracranial volume with the gamma rays emitted by the 201 sources of the isotope Co 60. Suitable indications for radiosurgery are cerebral arteriovenous malformations, benign and malignant intracranial tumors and functional diseases of the brain.