Radiosurgery

Radiosurgery is a medical procedure that allows non-invasive treatment of benign and malignant tumors and other brain pathologies, such as trigeminal neuralgia and some cases of epilepsy. The initial application of radiosurgery was in treatment of lesions in the brain, a technique also known as stereotactic radiosurgery (SRS). The compound word stereotactic is made up from Greek words: στερεος, which means solid, and τακτική (hinted τηχνη) which means "ability in disposition," meaning "tactic" as used in military language. In fact radiosurgery is stereotactic only if the distribution of radiation beams is in three dimensions and not in two as in traditional radiotherapy. In addition to cancer, it has also been shown to be beneficial for the treatment of some non-cancerous conditions, including functional disorders such as arteriovenous malformations (AVMs) and trigeminal neuralgia.

Radiosurgery operates by directing highly focused beams of ionizing radiation with high precision. It is a relatively recent technique (starting in 1951 with Gammaknife by Leksell in Stockholm)) which is used to destroy, by means of a precise dosage of radiation, intracranial and extracranial 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 inadvisable due to deleterious consequences for the patient, such as damage to nearby arteries, nerves, and other vital structures. The unit of Leksell was a kind of big helmet usable only for the cranium that was firmly fixed to the helmet. In 1982 the use of a linear accelerator of high precision combined with a Leksell's device fastened to the couch sustaining the patient and the precise capability of the couch to rotate around a vertical axis made possible to obtain three-dimensional treatments similar to those obtained with Gammaknife.

Recent innovations in radiosurgery (Cyberknife 1994) include platforms that sense the position of the patient and adjust the radiation to patient position, to avoid the effects of the movements of patient and the breathing motion, in order to keep the necessary precision to also irradiate a very small target. In such manner the method can be applied also to extracranial lesions, extending enormously the treatment possibilities.

The latest radiosurgery technology available as of 2009 included the CyberKnife and Gamma Knife Perfexion systems, the Novalis Tx radiosurgery platform, and the Trilogy linear accelerator by Varian.