The effect of patient positioning (prone or supine) on the dose received by small bowel in pelvic radiotherapy in rectal cancer patients.

PURPOSE The small bowel is a main dose-limiting organ in pelvic radiotherapy in the patients with rectal cancer. Conventionally, pelvic radiotherapy of patients with rectal cancer is performed in the prone position. MATERIAL AND METHODS Thirty-nine patients underwent CT planning scan in the treatment position (20 patients in prone position group and 19 patients in supine position group). After radiation treatment planning optimization, the volumes of the irradiated small intestines were investigated. RESULTS The volume of irradiated small bowel was higher in the supine position (mean difference; 36,274 cm3). However, it was not statistically significant (P value=0.187) CONCLUSION: Supine position could be accepted for the patients undergoing preoperative rectal cancer chemo-radiation.