This research study is studying proton radiation as a possible treatment for brain tumor that requires radiation.

The radiation involved in this study is:

-Proton Radiation

This research study is a Pilot Study to determine whether using proton therapy in participants that require craniospinal radiation (whole brain and spinal cord radiation therapy) with sparing of the bony spine will work. This is the first time investigators are examining bone sparing proton therapy in pediatric craniospinal radiation.

The FDA (the U.S. Food and Drug Administration) has not approved proton radiation for this specific disease but it has been approved for other uses.

In this research study, the investigators are studying proton radiation in participants that require craniospinal radiation. The standard of care for this procedure is photon radiation, which is very similar to proton radiation. The investigators believe that the precision of proton radiation may help to reduce the negative effects radiation has on the surrounding non-cancerous growing and developing tissue

Inclusion Criteria:

• Age ≥ 3 years and ≤ 18 years at the time of registration
• Histologically proven malignancy necessitating cranio-spinal irradiation. This will include patients with a diagnosis of medulloblastoma, Supratentorial primitive neuroectodermal tumor (SPNET), germ cell tumor (GCT), disseminated ependymoma, embryonal tumor with abundant neuropil and true rosettes (ETANTR), Atypical Teratoid/Rhabdoid Tumor (ATRT), and disseminated low-grade glioma (LGG).
• Life expectancy ≥ 12 months.
• Signed informed consent document and assent when appropriate.
• HGB of > 10 g/L and PLT count > 80 K/uL

Exclusion Criteria:

• Any prior therapeutic radiation therapy > 500 cGy has been delivered.
• Individuals with a history of a different malignancy are ineligible except for the following circumstances: if they have been disease-free for at least 5 years and are deemed by the investigator to be a low-risk for recurrence of that malignancy; or, have had only cervical cancer in situ, or basal cell or squamous cell carcinoma of the skin.
• Any major uncontrolled or poorly controlled intercurrent illness that would limit compliance with study requirements.
• Pregnant females are excluded. Females of childbearing age/menstruating must confirm that either they are not sexually active or have a negative pregnancy test prior to initiation of radiation therapy.
• Patients that receive concurrent chemotherapy with the exception of concurrent Vincristine.