Effect of customized small bowel displacement system in pelvic irradiation

Purpose: Authors designed a customized small bowel displacement system (SBDS) to displace the small bowel out of the pelvic radiation fields and to minimize treatment related bowel morbidity. Methods and Materials: From August 1995 to May 1996, 55 consecutive patients who received pelvic radiation therapy with the SBDS were included in this study. The SBDS consists of a customized Styrofoam compression device that can displace the small bowel out of the radiation fields and an individualized immobilization abdominal board for easy daily setup of the patient in prone position. After opacifying the small bowel with barium, the patients were laid prone and posterior-anterior (PA) and lateral (LAT) simulation films were taken with and without the SBDS. The volume of the small bowel included in the radiation fields with and without the SBDS were compared. Results: Using the SBDS, the mean small bowel volume was reduced by 59% on PA and 51% on LAT films (p = 0.0001). In six patients (6 of 55, 11%), it was possible that no small bowel was included within the treatment fields. The mean upward displacement of the most caudal small bowel was 4.8 cm using the SBDS. Patients treated with the SBDS manifested a significantly lower incidence of diarrhea requiring medication (8 of 55, 15%) vs. those without the SBDS (24 of 39, 62%) (p < 0.05). Conclusion: The SBDS is a novel method that can be used to displace the small bowel away from the treatment portal effectively and to reduce the radiation therapy morbidity. Compliance with setup is excellent.