Pilot Trial of Short Course Radiotherapy for Primary or Secondary CNS Malignancies

Inclusion Criteria: * Male or female, aged 21 years or below * Lansky performance status \>= 40 * Has a diagnosis of an incurable malignancy that: * Originates outside the brain but is metastatic to 1 or more sites within the brain, or originates and recurs within the brain. For this diagnosis to be confirmed, there must be multidisciplinary review of up to date imaging at a pediatric tumor board with unanimous consensus of intracranial relapse or metastasis. If the consensus is not unanimous, short-interval repeat imaging with subsequent unanimous consensus would be required in order for this eligibility criteria to be met * Has at least 1 targetable intracranial lesion as seen on imaging * Has a multidisciplinary consensus recommendation for palliative intent radiation * Consents to the study or has caregiver who is able to provide signed and dated informed consent. For subjects under the age of 18, a signed and dated assent form as able. * Patients who had prior radiation in planned treatment area are also eligible to enter the trial * Stated willingness to comply with all study procedures and availability for the duration of the study Exclusion Criteria: * Radiotherapy for curative intent * Serious uncontrolled systemic or psychiatric disorders that would interfere with participation in the protocol * Being planned for proton radiation