Study of Stereotactic Radiosurgery to the Subventricular Zone in Malignant Gliomas

Inclusion Criteria: * Consent to participate in a clinical trial * Confirmed WHO III or WHO IV malignant glioma, based upon Northwell Health neuropathology review. Outside cases must be submitted for central neuropathology review. * Completion of major surgical debulking procedure, defined as residual tumor volume of less than 20% original mass * Age greater than 18 years old. Children are not included because their disease behaves in a biologically distinct manner and there are already national clinical trials specific to them * Patients will not be excluded on the basis of advanced age (i.e., \>75 years old), but there will need to be an intent to deliver standard chemoradiation therapy. Patients scheduled for accelerated radiation therapy are ineligible * Karnofsky performance status of 50 or higher. Patients may require considerable assistance and frequent medical care. * Willingness to sign HIPAA authorization that allows the investigators to continue to obtain clinical information even if patient leaves the study institution for care elsewhere in order to collect long term outcome and toxicity data. * Lobar tumor location (Frontal, temportal, parietal, occipital, or thalamic) Exclusion Criteria: * Inability to consent to participate in a clinical trial, as determined during the standard of care practice evaluation of a malignant brain tumor patient. * Prior malignant glioma treatment less than 12 months prior to chemoradiation therapy, other than surgery with or with…