The effect of belly board location in rectal cancer patients treated with preoperative radiotherapy.

AIMS

To evaluate the effect of the belly board aperture location on the irradiated small bowel volume in rectal cancer patients treated with preoperative pelvic radiotherapy.

MATERIALS AND METHODS

Twenty patients with rectal cancer scheduled to receive preoperative pelvic radiotherapy were evaluated prospectively. Each patient underwent computed tomography with the belly board aperture lower border at three different locations relative to patient anatomy: the lumbosacral junction (location I), the lower end of the sacroiliac joint (location II) and the upper end of the symphysis pubis (location III). The irradiated small bowel volume was calculated for doses between 10 and 100% of the prescribed dose at 10% intervals. For each 10% dose increment, the effect of the belly board aperture at the three different locations on the irradiated small bowel volume was analysed using Wilcoxon signed rank and Wilcoxon rank sum tests.

RESULTS

At 10-20% dose levels, the irradiated small bowel volume increased in the order of locations I, II and III, and the differences between each location were significant. At > or = 30% dose levels, the irradiated small bowel volume increased in the order of locations III, II and I, and the differences between locations I and II were significant, but the differences between locations II and III were not significant.

CONCLUSION

The belly board aperture location can influence the irradiated small bowel volume differently at each dose level. When considering the use of a belly board in routine clinical practice, we recommend that the clinician take into account the patterns of irradiated small bowel volume according to belly board aperture location.