One approach to limit toxicity from external beam radiotherapy is the use of intensity modulated radiation therapy (IMRT). IMRT can limit radiation dose to normal rectum (above and below the tumor) and surrounding organs at risk (OARs) such as bladder and sexual organs. IMRT utilizes multiple beams of radiation to treat the rectal tumor plus a margin and limits dose to OARs. While IMRT decreases radiation dose to normal structures, it requires an additional 2-3 cm margin for microscopic extension (clinical treatment volume=CTV), set-up error, and rectal motion (planning treatment volume=PTV). Furthermore, IMRT still requires 5-6 weeks of radiation with concurrent chemotherapy, is substantially more expensive than conformal radiation, and is especially prohibitive in countries where access to technology necessary for IMRT is limited (20). Based on the preliminary results of RTOG 0822 and others, it still remains to be determined whether IMRT confers a statistically significant improvement in pCR, toxicity rates and QOL relative to standard NCRT.