Intensity-modulated radiotherapy with a belly board for rectal cancer

Abstract

Intensity-modulated radiotherapy (IMRT) techniques can reduce the irradiated small bowel volume in rectal cancer patients, but combined use of IMRT and a belly board is yet to be reported on for rectal cancer patients. The aim of this study was to determine whether additional use of a belly board reduced the irradiated small bowel volume observed using IMRT alone in rectal cancer patients. Twenty patients scheduled to receive preoperative radiotherapy for rectal cancer underwent two series of CT scans, with and without a belly board. IMRT planning was performed using 6-MV photon beams and seven equispaced fields. The bladder, small bowel, and planning target volume (PTV) were analyzed for doses between 10% and 100% of the prescribed dose at 10% intervals. Data were analyzed using Wilcoxon signed rank tests. There were no significant differences between patients undergoing IMRT with a belly board and those without a belly board in terms of total small bowel volumes, bladder, and PTV (p=0.571, p=0.841, and p=0.870, respectively). Statistical analysis showed that the irradiated small bowel volume with a belly board was smaller than that without a belly board (p<0.05 at 20-100% dose levels), with the mean relative reduction in the irradiated small bowel volume being 37.8+/-32.8%. IMRT with a belly board is more effective than IMRT alone in reducing the irradiated small bowel volume. These findings suggest that the use of a belly board with IMRT may reduce small bowel complications in preoperative radiotherapy.