Technical overview of gamma knife radiosurgery

Abstract

The Gamma Knife (GK) technology is developed for stereotactic radiosurgery (SRS). In 1951 Swedish physician Lars Leksell invented stereotactic fixation frame to target beam of radiation into human brain using polar coordinates. Later this system was used to develop the Gamma Knife in 1967 by L. Leksell and B. Larsson in Stockholm, Sweden. For GammaKnife photon radiation Cobalt-60 source was selected. Half-life of Cobalt-60 is 5.26 years and emitted gamma photons are 1.17 MeV and 1.33 MeV energy. First GK prototype was used for neurological surgery for treatment of patients with pain and movement disorders. In 1972 L. Leksell established “Elekta” and continued to improve this technology. Today without prototypes are established Leksell Gamma Knife models: U (A), B, C, 4C, Perfexion and Icon. Introduction Original Gamma Knife had 201 Cobalt-60 sources arranged in a hemispheric configuration and was installed in Sophiahemmet Hospital, Sweden [1]. It was designed for precise and efficient stereotactic radiosurgery for intracranial radiosurgery to treatpituitary tumours, vestibular schwannomas, vascular malformations and functional disorders. The collimation system in GK focuses individual beams of gamma radiation to precise focus point, thus minimizing biological radiation effect for healthy cells. During radiosurgery, stereotactic frame is attached to patient’s head and external collimator helmet (GK U and helmetis in Fig. 1). Typically, one single fraction of radiation in one treatment day. Later new version of Leksell Gamma Knife Model U (A) was developed with computer dose planning system and so decreased dose to patient’s body. Because of hemispheric sources configuration there was challenging issues with load and reload in this early GK models.. […].