Radiosurgery is surgery using ionizing radiation to destroy selected regions of tissue rather than excision with a blade. It is used to treat cancer just like other forms of radiation therapy. The basic principle of radiosurgery is that of selective ionization of tissue, by using radiation beams of high-energy.

The production of free radicals and ions which are usually harmful to the cells is called as Ionization. Irreparable damage can be caused to DNA, proteins and lipids by these ions and radicals, which may be created from the water in the cell or from the biological materials, resulting in cell death. Biological inactivation is therefore carried out with a precise destructive effect, in a bulk of tissue to be treated. The word stereotactic in ‘stereotactic radiosurgery’ refers to a 3-D coordinate system. Accurate correlation of virtual target as viewed in the diagnostic images of patient with the actual target position in the patient anatomy is enabled by this 3-D coordinate system. Radiosurgery is carried out by a multidisciplinary team of radiation oncologists and medical physicists, who operate and maintain instruments that are extremely sophisticated, highly accurate and complex, like the Gamma Knife and Medical Linacs.

After using information from medical images obtained by means of computer tomography, angiography and magnetic resonance, a highly precise irradiation of targets within the brain and spine is planned. Radiosurgery is mainly recommended for tumour therapy, vascular lesions and functional disorders. The outcome of radiosurgery may not be seen immediately and would take months post treatment. Radiosurgery causes the biological inactivation of tumour and does not eradicate it, therefore lack of lesion growth is generally considered to be a success in treatment. Many types of brain tumours like germinomas, neuromas, meningionomas, acoustic neuromas, metastases, arteriovenous malformations, trigeminal neuralgia, skull base tumours etc. are the common indicators for radiosurgery.