Frameless Stereotactic Radiosurgery for Brain Metastases

Inclusion Criteria: * Patients with brain metastases from a biopsy-proven primary extra-cranial tumor site, excluding lymphoma, germ cell, and small cell lung carcinoma histologies. * One to four metastases, and all lesions \< 3.5 cm in maximal diameter. Extracranial metastases is of minimal volume or stable with treatment. - Karnofsky performance status ≥ 70 Exclusion Criteria: * None of the lesions is abutting or within critical neurological structures: \*brainstem * optic chiasm * eye, and optic nerve. * The clearance between metastatic lesions and all critical structures must be at least 2 mm. * Patients must not have leptomeningeal disease. * Contraindications to imaging or radiation (e.g. pregnancy, elevated serum creatinine, allergy to contrast agents, severe claustrophobia, metal particles in the eye).