Organ-Sparing Marrow-Targeted Irradiation Before Stem Cell Transplant in Treating Patients With High-Risk Hematologic Malignancies

Inclusion Criteria: * Patients with a diagnosis of acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), or myelodysplastic syndromes (MDS) with fewer than 10% myeloblasts or lymphoblasts in the bone marrow and no blasts in the peripheral blood on morphologic analysis performed within 30 days of start of the conditioning regimen; if remission bone marrow is available beyond 30 days a new bone marrow evaluation is required to assess remission status * The diagnosis of AML, ALL, or MDS will be based on World Health Organization (WHO) criteria * Pre-transplant bone marrow sample must be evaluable for assessment of remission status (i.e. aspirate smear containing particles and/or evaluable bone marrow core biopsy) * Patients with leukemia infiltration in the central nervous system (CNS) are eligible if cerebrospinal fluid (CSF) cytospin is negative for myeloblasts or lymphoblasts at time of enrollment * If the patient has an intra-abdominal chloroma on presentation, and has a partial response or complete response to treatment (size reduction of chloroma and marrow blast \< 10%), the patient is eligible; however the chloroma must be included as part of the treatment target * For patients receiving treatment of their AML, MDS or ALL prior to transplantation: * Interval between the start of a cycle of conventional cytotoxic chemotherapy and the start of conditioning regimen must be at least 30 days * Interval between completing treatment with a hypomethyla…