Low Dose Radiation Therapy for Glioblastoma Multiforme

Inclusion Criteria: * Patients must have recurrent GBM (Glioblastoma Multiforme)or Anaplastic Astrocytoma. * The diagnosis of GBM or Anaplastic Astrocytoma. * Patients must have been previously treated with surgical resection (any extent okay) and adjuvant radiation therapy plus temozolomide. * Patients must be at least 12 months from completion of radiation therapy * At least 2 months from completion of temozolomide (to be consistent with the the "rechallenge" group from Perry et al. JCO 2010). * Age \>18 years * ECOG performance status \<2 (Karnofsky \>60%, see appendix A). * There must be measurable disease on MRI. * Patients must have normal organ and marrow function as defined below: * Women must not be pregnant * Ability to understand and the willingness to sign a written informed consent document * Temozolomide re-treatment is planned by the treating neuro-oncologist. * The most recent brain tumor pathology obtained for the patient must be glioblastoma. Exclusion Criteria: * Must be able to receive an MRI * Patients may not be receiving any other investigational cancer treatment agents at the time of enrollment. * Patients may not have previously failed treatment with salvage temozolomide. * Patients may not have previously failed treatment with a VEGF inhibitor. * Patients may not have previously been treated with \>1 course of radiotherapy. * Patients may not have previously been treated with radiosurgery to the brain. * Uncontrolled intercurrent illness * Pregnan…