LET Optimized IMPT in Treating Pediatric Patients With Ependymoma

Inclusion Criteria: * Previous pathologic confirmation of ependymoma, World Health Organization (WHO) grade II or III * Disease must be confined to the brain (no evidence of spread on MR imaging of the spine or on staging lumbar puncture) * Patient may not receive chemotherapy concurrent with radiation * Signed informed consent by patient and/or parents or legal guardian * Lansky performance status score of 50 -100 Exclusion Criteria: * Patients with previous radiation therapy to the brain * Ependymoma of the spine * Disseminated ependymoma requiring craniospinal radiation therapy * Pregnancy * Inability to undergo MR imaging * Inability to receive gadolinium-based contrast agent