Previous pelvic irradiation, prostate brachytherapy, or bilateral orchiectomy Patients who have received previous vaginal, pelvic, or abdominal irradiation Prior radiotherapy (RT): At least four weeks since completion of whole-brain irradiation, at least two weeks since completion of prophylactic cranial irradiation, and to any other site. Patients must have had their last fraction of: \r\n* Craniospinal irradiation (> GRAY [Gy]) or total body irradiation > weeks prior to enrollment\r\n* Focal irradiation > weeks prior to enrollment\r\n* >= months since autologous bone marrow/stem cell transplant prior to enrollment Patient has received radiation therapy prior to study registration; patients must have had their last fraction of local irradiation to the primary tumor >= months prior to registration, their last fraction of craniospinal irradiation (>= Gy) or total body irradiation >= months prior to registration or >= weeks (wks) for the therapeutic doses of MIBG; patient has not received focal irradiation for symptomatic metastatic sites within days prior to registration Prior total body or hemi-body irradiation Subject who has received prior pelvic irradiation or is scheduled for pelvic nodal irradiation Radiation therapy within weeks prior to randomization, including stereotactic or partial brain irradiation. Whole brain irradiation within weeks prior to randomization Radiation: patients must have:\r\n* Had their last fraction of local irradiation to primary tumor >= weeks prior to registration; investigators are reminded to review potentially eligible cases to avoid confusion with pseudo-progression\r\n* Had their last fraction of craniospinal irradiation or total body irradiation >= weeks prior to registration Participants may have received prior cranial irradiation Disease has progressed through at least one systemic therapy or through local irradiation within the preceding months. Radiotherapy: patients must have had their last fraction of: \r\n* Focal irradiation > weeks prior to enrollment Prior prophylactic cranial irradiation (PCI) is allowed Radiation: patients must have:\r\n* Had their last fraction of local irradiation to primary tumor >= months prior to registration; investigators are reminded to review potentially eligible cases to avoid confusion with pseudo-progression\r\n* Had their last fraction of craniospinal irradiation (> Gy) > months prior to registration Prior irradiation to > % of BM reserves (including total body irradiation), regardless of the washout period; Prior radiation: Cranial irradiation, total body irradiation (TBI), or ? % radiation of pelvis ? months prior to screening. Focal irradiation: ? weeks prior to screening if radiation field involved a nontarget lesion; ? weeks prior to screening if radiation field involved a target lesion. Note: True disease progression following prior irradiation therapy must be confirmed by Investigator prior to screening. Bone marrow transplant: < months since allogeneic bone marrow transplant prior to screening. < months since autologous bone marrow/stem cell transplant prior to screening. < months since stem cell transplant (SCT) or Rescue without TBI with no evidence of GVHD prior to screening. Radioisotopes: fluorothymidine (FLT) ? hours prior to first dose of study drug Plans to administer irradiation to the breast only Prior whole brain irradiation Previous pelvic irradiation therapy history of mediastinal or pulmonary irradiation Prior conventional irradiation of the spine site and level to be treated with an interval shorter than months History of prior irradiation to the area to be treated Treatment plan that includes regional nodal irradiation Previous irradiation that precludes the safe administration of an additional dose of cGy of total body irradiation (TBI) Previous total body irradiation, or irradiation of >% of the patient's bone marrow. Patients who have received previous vaginal, pelvic, or abdominal irradiation Prior whole brain irradiation Prior mediastinal irradiation (for any reason) Prior whole brain irradiation Prior whole brain irradiation Previous pelvic irradiation, prostate brachytherapy Prior total body irradiation (TBI) Prior total body irradiation, prior total abdominal or whole liver radiation Patients must not have received previous irradiation to the brain Previous pelvic irradiation, prostate brachytherapy, or bilateral orchiectomy Progressive intracranial ependymoma after prior focal irradiation Prior craniospinal irradiation Prior intracavitary irradiation or Gliadel wafers Previous pelvic irradiation, prostate brachytherapy, or bilateral orchiectomy Prior whole brain irradiation Patients must have had their last fraction of: \r\n* Craniospinal irradiation (> Gy) > months prior to enrollment\r\n* Focal irradiation > days prior to enrollment\r\n* Local palliative irradiation (small port) > days Treatment plan that includes regional nodal irradiation Prior whole brain irradiation Prior cranial irradiation Patients who have received cranial or spinal irradiation less than weeks prior to the start of this protocol Stem cell infusions (with or without total body irradiation [TBI]): ? days ? weeks for total skin electron beam irradiation, Patients are excluded if they have received total body irradiation (TBI) Prior whole brain irradiation Prior whole brain irradiation. Patients must have:\r\n* Had their last fraction of local irradiation to primary tumor >= weeks prior to registration\r\n* Had their last fraction of craniospinal irradiation or total body irradiation >= weeks prior to registration Prior neck radiotherapy that would preclude re-irradiation Prior irradiation is allowed if > days prior to registration have elapsed since\n the date of last treatment. Patients with a history of pelvic irradiation for any reason Prior cranial irradiation Patients who have received prior pelvic irradiation are not eligible At least weeks for craniospinal, ?% radiation of pelvis, or total body irradiation prior to first dose of study drug Previous pelvic radiotherapy that would prevent prostate/seminal vesicle (SV) irradiation No prior abdominopelvic radiotherapy is allowed except for total body irradiation administered >= years prior; no prior systemic therapy for anal cancer Total body irradiation (TBI) or craniospinal radiation therapy = % radiation of pelvis > months prior to enrollment\r\n* Focal irradiation > weeks prior to enrollment\r\n* Local palliative radiation therapy (XRT) (small port) >= weeks Surgery or irradiation ? weeks prior to randomization Recommended to undergo pelvic irradiation with concurrent chemotherapy Prior abdomino-pelvic irradiation Prior irradiation of the spine site and level to be treated Patients who have received previous vaginal, pelvic, or abdominal irradiation Prior pelvic irradiation. No history of previous chemotherapy or pelvic irradiation History of prior chemotherapy or pelvic irradiation Patients must not have received any prior pelvic irradiation Patients must be at least weeks out from pelvic irradiation, and must not have more than % of bone marrow irradiated. Patients who have received cranial or spinal irradiation less than weeks prior to the start of this protocol Previous pelvic irradiation, prostate brachytherapy RECURRENT/ PROGRESSIVE DIPG (STRATUM ): Patients must have had their last fraction of: \r\n* Craniospinal irradiation or radiation to >= % of pelvis > months prior to enrollment\r\n* Focal irradiation to the primary site > days prior to enrollment\r\n* Local palliative irradiation other than previously irradiated primary site (small port) >= days NON-PROGRESSED DIPG (STRATUM ): Patients must have had their last fraction of focal irradiation to the primary site > days prior to enrollment; patients must not have received local palliative irradiation or craniospinal irradiation Prior total body irradiation (TBI) making TMI not feasible Patients who have pelvic irradiation with doses ? Grays (Gy). At least days from prior total body irradiation (TBI) Patient had a resection and/or completed a course of cranial irradiation; and Patients with prior whole brain irradiation Prior history of pelvic irradiation History of extensive prior pelvic irradiation. Has undergone chest irradiation within weeks prior to randomization (except palliative irradiation of bone lesions) External radiation therapy (XRT): Must not have received XRT within months prior to study entry for craniospinal irradiation (> Gy) or total body irradiation or if >= % radiation of pelvis; >= weeks for local irradiation to primary tumor; >= weeks for focal irradiation for symptomatic metastatic sites Prior whole brain irradiation Evidence or suspected recurrent or metastatic disease; prior brain irradiation is not allowed Participants with a history of pelvic irradiation; or chemotherapy or radiotherapy within the preceding days Disease-based radiation therapy (not total body irradiation) Patients receiving prior external beam irradiation to the head or neck, including any form of stereotactic irradiation Regional nodal irradiation is part of the treatment plan Subjects who have previously received or have planned Total Body Irradiation (TBI) Patient has received or is scheduled to receive total body irradiation, total nodal irradiation, upper abdomen radiotherapy, half or upper body irradiation, radiotherapy of the cranium, craniospinal regions, head and neck, lower thorax region or the pelvis within week prior to study entry (Day ) or within h after start of chemotherapy administration on Day . Indications for comprehensive regional nodal irradiation Prior pelvic irradiation History of re-irradiation to a field which includes the carotid arteries