The purpose of this report is to present the physical aspects of stereotactic radiosurgery and give more through explanation of the technique which use linear accelerator-produced photons. The fixed reference stereotactic frames, the imaging of the frames and positioning of the patient for diagnostic and treatment procedures are briefly described. The dosimetry of narrow photon beams, depth-dose characteristics of megavoltage photons, isodose distributions in the transverse, sagittal, and coronal planes for various linac-based radiosurgery techniques are discussed.
The survey of experience in linac-based radiosurgery is given as well as the detailed description of dosimetric measurements for 15 MV X-ray beam from Mevatron, performed by the author in German Cancer Research Centre at Heidelberg.