Stereotactic radiosurgery

Stereotactic radiosurgery (SRS) is a form of precisely targeted radiation therapy that delivers a high radiation dose to a defined intracranial lesion while limiting exposure to surrounding brain tissue. Despite its name, it is noninvasive and does not involve an incision. Treatment may use systems such as gamma knife radiosurgery or linear-accelerator platforms and may be delivered in a single session or in a small number of fractions. Accurate immobilization, image guidance, dose calculation, and quality assurance are essential, particularly when treating multiple lesions with a single isocenter.

SRS is used as focal therapy for selected cranial conditions, including brain metastases, recurrent glioblastoma, embryonal and germ cell tumors, vestibular schwannomas, and cerebral cavernous malformations. Its therapeutic effect is mediated primarily by concentrated ionizing radiation that damages cellular DNA within the target, producing tumor control or lesion injury over time. Current work includes comparisons with whole-brain radiotherapy and laser interstitial thermal therapy, evaluation of local control and local failure, and analysis of radiographic changes after treatment. Planning research addresses tumor volume, margin dose, target geometry, plan complexity, and dosimetric algorithms, with outcomes also examined using measures such as the Karnofsky scoring system, Kaplan–Meier method, Cox proportional hazards model, Brier score, and area under the curve.