RecruitingPhase 1Radiation therapyHypofractionation (Radiation) Trial for Multiple MyelomaThis study if for people who have been diagnosed with multiple myeloma and their doctors are recommending radiation to help treat it. Typically, radiation consists of 2-3 weeks of external beam radiation therapy. Doctors leading this study would like to see if a shorter radiation course (i.e., hypofractionation) for pelvic radiation is safe for multiple myeloma. Because participants in this study will receive a shortened radiation course, each daily treatment dose that is delivered would be slightly higher than normal. This higher daily dose would be delivered because the study team would like to see if higher doses of radiation are as safe given over a shorter number of days compared to 2-3 weeks. The purpose of this study is to make sure that hypofractionation is safe and effective for individuals with multiple myeloma.