To accomplish these objectives, the investigators will recruit 20 patients for treatment with helical tomotherapy. Patients with solid malignancy of any primary site with proven or suspected metastatic disease involving the abdomen, pelvis, or bones of the lumbar spine or pelvis will be eligible, provided they are over 18 years of age; signed informed consent is obtained; and there are no contraindications for radiotherapy. The investigators will select patients for enrollment who have a high likelihood (>50%) of suffering from grade 2 or higher acute GI toxicity if standard radiotherapy techniques were used. Treatment will be delivered with the helical tomotherapy system, with the dose plan designed to treat the target volume to a homogeneous dose, while minimizing dose to normal structures including the small bowel. The first 10 patients will be treated with a dose of 2500 cGy in 10 fractions, and the second cohort of 10 patients to 3000 cGy in 10 fractions. The slightly lower than normal dose used for the first cohort is designed to provide an extra margin of safety.