RecruitingRadiation therapyREMIND Maintenance Radiotherapy for Newly Diagnosed GlioblastomaREMIND is a single-center feasibility study testing maintenance radiotherapy in adult patients with newly diagnosed glioblastoma. Participants will be consented before starting standard-of-care concurrent temozolomide and radiotherapy. After enrollment, participants will enter an observational lead-in phase while receiving standard-of-care therapy off study. Approximately 4 weeks after temozolomide, participants will receive one study-specific 2 Gy fraction of maintenance radiotherapy directed at the post-operative cavity and areas of prior enhancing disease. The study will evaluate the safety and feasibility of delivering maintenance radiotherapy. Blood samples will also be collected before and after maintenance radiotherapy to descriptively compare myeloid-derived suppressor cell frequency.