In addition, patients with positive para-aortic lymph nodes on PET, greater amounts (more than 45 Gy) of radiation must be used to improve the probability of controlling the cancer. However, doses greater than this have been limited because of the dose and volume limits to the small bowel. But, Intensity Modulated Radiation Therapy (IMRT) is a new way of calculating and delivering radiation therapy. Compared to external beam radiation, IMRT has the improved ability to deliver large doses of radiation to specific targets while minimizing the exposure to surrounding normal tissue.