Radiosurgery Techniques for Brain Metastases

As a notable cause of cancer-related morbidity and mortality, brain metastases (BMs) represent the most prevalent intracranial tumors arising in up to 40% of all adult solid tumors during the course of treatment. Intracranial stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) gained wide appreciation by the radiation oncology communities for the treatment of BM with regards to the grim prognosis of such patients after alternative therapies, including the whole brain radiotherapy (WBRT).  Additional concerns on the neurocognitive deterioration and comparably low tumor control rates offered by the conventional WBRT further quickened the implementation of SRS to the daily practice of radiation oncology clinics. However, the striking diversities among the treatment algorithms and the treatment planning systems of the gamma knife-, linear accelerator- (LINAC), tomotherapy-, robotic Cyberknife-, or the proton therapy-based SRS render the administration of SRS/FSRT challenging. Acknowledging these difficulties, the present review intended to offer a thorough outline of the main principals of the SRS/FSRT technique from the initial patient fixation to the final machine and dose delivery quality assurance treads.