RecruitingPhase 3Radiation therapyA Study of Reduced Dose Radiation Therapy for People With B-Cell LymphomasThe researchers are doing this study to find out whether a very low dose of radiation therapy (VLDRT) is an effective treatment for people with follicular lymphoma (FL) or marginal zone lymphoma (MZL) and works as well as the standard dose of radiation therapy. The researchers will see if VLDRT works against cancer in the area that is currently affected by cancer and if the therapy prevents new spots of lymphoma from developing. The researchers will also compare VLDRT with the standard dose of radiation therapy to see if VLDRT causes fewer side effects. Radiation therapy uses beams of intense energy to kill cancer cells. Standard doses of radiation therapy can cause short- and long-term side effects. Researchers think VLDRT may be as effective as standard doses, and, because VLDRT uses less radiation, researchers think VLDRT may cause fewer side effects than standard doses.