 2. Patients with newly diagnosed or progressive DIPG as confirmed by gadolinium enhanced MRI are eligible. MRI must demonstrate that at least 23 of the tumor is situated in the pons and that the origin of the tumor is clearly in the pons. Biopsy is not required. Tumors with features not typical of diffuse intrinsic brainstem glioma are not eligible. These include dorsally exophytic brainstem gliomas, cervicomedullary junction tumors, and focal low grade gliomas of the midbrain or brainstem which should undergo resection and pathologic evaluation. Patients, who have received re-irradiation for progression of the tumor, will be eligible if they show evidence of measurable progressive disease after the re-irradiation. Patients at diagnosis with involvement of the spine will not be eligible, however if at progression features of spine involvement are present they will be eligible for Stratum II. 