Precision Radiotherapy Enabled by Molecular MRI

Inclusion Criteria: * Histologic confirmation of glioblastoma or grade 4 astrocytoma * Age \>18 * KPS at least 60 * Patients must have normal organ and marrow function as defined below: * leukocytes \>3,000/mcL * absolute neutrophil count \>1,500/mcL * platelets \>100,000/mcL * total bilirubin within normal institutional limits * AST(SGOT)/ALT(SGPT) \<2.5 * institutional upper limit of normal * creatinine within normal institutional limits OR creatinine clearance \>60 mL/min/1.73 m2 for patients with creatinine levels above institutional normal. * Patients of child-bearing potential (male or female) must practice adequate contraception due to possible harmful effects of radiation therapy on an unborn child. * Ability to understand and the willingness to sign a written informed consent document. Exclusion Criteria: * Patients who are unable to receive MRIs will be excluded from the study. * Patients may not be receiving any other investigational cancer treatment agents at the time of enrollment. * Patients may not have previously been treated with an overlapping course of radiotherapy to the brain. * Uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * Pregnant and/or breastfeeding women are excluded. Women of child-bearing potential who are unwilling or unable to use an acceptable method of birth control to avoid pregnancy for the entire study period and up to 12 weeks after the study are excluded. Male subjects must also agree to use effective contraception for the same period as above.