I scheduled my radiation treatment for 11:30AM, since my bowels worked like clockwork and were naturally empty by then -- a consideration that can ease cocerns of empty bowel and no gas. My RO had instructed me to take milk-of-magnesia and Gas-X the night before the RT. The former kept stools soft (could be tapered if they became too soft) and the latter helped prevent gas. She also recommended avoiding gas producing foods for the duration of RT. Of course, check with your RO before taking any OTC meds or supplements.