Stereotactic radiation is the term applied to treatment methods and techniques which enable a high dose of radiation to be administered very precisely to a previously defined target volume of tissue. Steep dose gradients outside the target volume provide optimum protection of neighbouring, healthy structures which are susceptible to radiation.

The necessary geometric precision is achieved by using stereotactic localization and positioning systems (mask systems). A system of external coordinates enables targets inside the patient's body to be defined to an accuracy of a few millimetres. Therapy is planned using three-dimensional computed tomography, and the tumour is then radiated from outside the body from several directions with pin-point accuracy. Each of the fields along the beam contains such low energy that healthy tissue which is exposed to radiation is barely affected. All the beams converge at a point inside the target volume, where they combine to produce the required high dose.

Radiosurgery and fractionated stereotactic precision radiation are used mainly for localized lung tumours, liver metastases and brain metastases.