The Gamma Knife is the technically most advanced instrument in radiosurgery.  it is a prcision tool for medical iiadietion making it possible to eliminate lesiona in the brain. Since its therapeutic effect can be compared to that of a surgeon´s knife, the name Gamma Knife was established. In 1968 the Gamma Knife was first used for patient treatment and the Gamma Knife method has now been used for more than three decades during which a lot of clinical experience has been gathered. Subsequent and continuous improvements have turned the Gamma Knife into the technologically advanced precision tool in neurosurgery it is today.

The Leksell Gamma Knife uses 201 finely focused beams of Co-60 gamma rays. They are semi spherically positioned around the head of a patient. These beams simultaneously intersect at a precise location (see figure to the right).It is only in the very center of this intersection that the delivered dose will be biologically effective. Therefore, the patient is positioned in such a way that the lesion is moved exactly in this focus point. Depending on the shape of the lesion several positions (isocenters) may have to be chosen to completely cover the lesion with the necessary dose.