Effect of rectal enemas on rectal dosimetric parameters during high-dose-rate vaginal cuff brachytherapy A prospective trial

Purpose To evaluate the effects of rectal enemas on rectal doses during postoperative high-dose-rate (HDR) vaginal cuff brachytherapy (VCB). Patients and methods This prospective trial included 59 patients. Two rectal cleansing enemas were self-administered before the second fraction, and fraction 1 was considered the basal status. Dose-volume histogram (DVH) values were generated for the rectum and correlated with rectal volume variation. Statistical analyses used paired and unpaired t-tests. Results Despite a significant 15 % reduction in mean rectal volume (44.07 vs. 52.15 cc, p = 0.0018), 35.6 % of patients had larger rectums after rectal enemas. No significant rectal enema-related DVH differences were observed compared to the basal data. Although not statistically significant, rectal cleansing-associated increases in mean rectal DVH values were observed: D-0.1 cc: 6.6 vs. 7.21 Gy; D-1 cc: 5.35 vs. 5.52 Gy; D-2 cc: 4.67 vs. 4.72 Gy, before and after rectal cleaning, respectively (where D-x cc is the dose to the most exposed x cm(3)). No differences were observed in DVH parameters according to rectal volume increase or decrease after the enema. Patients whose rectal volume increased also had significantly larger DVH parameters, except for D-5 %, D-25 %, and D-50 %. In contrast, in patients whose rectal volume decreased, significance was only seen for D-25 % and D-50 % (D-x % dose covering x % of the volume). In the latter patients, nonsignificant reductions in D-2 cc, D-5 cc and V-5 Gy (volume receiving at least 5 Gy) were observed. Conclusion The current rectal enemas protocol was ineffective in significantly modifying rectal DVH parameters for HDR-VCB.