Observational Trial of the Impact of Radiation Dose in Children With Brain and Skull Base Tumors.

Inclusion Criteria: * Patient (parent) must give study-specific informed consent on an IRB-approved consent prior to any research related procedures or study treatment. Written assent will be obtained as per Institutional guidelines. * Patients (Age equal to or less than 35 years old) that are planned to receive photon or proton RT to the brain according to standard of care are eligible to participate. * Patients that are planned to receive fractionated RT at 1.2-2.0 Gy RBE dose per fraction per standard of care are eligible to participate. If patients are planned to receive an alternative dose/fractionation regimen, then they should be treated according to standard of care and should not be enrolled. * Zubrod/Eastern Cooperative Oncology Group (ECOG) Performance Status ≤1 Exclusion Criteria: * Patient cannot undergo MRI without contrast as per standard of care * Patient and family do not speak English or Spanish * Patient receiving treatment with non-curative intent * Patients with an expected 3-year overall survival less than 50%