Small-bowel displacement system for the sparing of small bowel in three-dimensional conformal radiotherapy for cervical cancer

Aims: The efficacy of the small-bowel displacement system (SBDS) in three-dimensional conformal radiotherapy (3-D CRT) planning for sparing the volume of small bowel is presented for cervical cancer. Materials and methods: Ten consecutive patients, who received pelvic radiation therapy for uterine cervical cancer with the SBDS from January to March 2003, were included in this study. The SBDS consists of a customised Styrofoam compression device, which can displace the small bowel out of the radiation fields, and an individualised immobilisation board. With oral contrast before scanning, computed tomography was taken in the prone position with and without the SBDS. 3-D conformal planning was carried out, and dose distribution was compared in the target volumes and in the organs-at-risk with and without the SBDS. Results: In all patients, the SBDS significantly reduced the small-bowel volume within radiation fields. The median small-bowel volume with SBDS was reduced by 56.4% compared with the small-bowel volume without SBDS (from 491 to 214 cm(3); P = 0.004). Among the 10 patients, the highest small-bowel volume reduction was 70.2% (from 544 to 62 cm 3). At the prescription dose, the median volume of small bowel irradiated was reduced significantly with SBDS (9.8% vs 1.2%; P = 0.005). Differences in the dose-volume histogram for the rectum and the bladder between the 3-D CRT plans with and without SBDS were not statistically significant (P > 0.1). All patients completed radiotherapy without a break in treatment. Conclusion: The SBDS is a novel method that can be used to displace the small bowel away from the 3-D CRT fields effectively, and reduce radiation therapy morbidity. (C) 2004 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.