Comparison of rectal and bladder dose between retractor insertion and gauze packing in intracavitary brachytherapy for cervical cancer.

This study aimed to compare and verify the rectal and bladder doses of intracavitary brachytherapy (ICBT) using both rectal retractor (RR) and gauze packing (GP) in the same patients. A total of 37 patients who underwent ICBT using RR and GP for cervical cancer were included in this study. Rectal and bladder dose and volume data were compared with the RR and GP treatments in the same patients and the confounding factors were examined. When comparing RR and GP, the median and interquartile ranges for rectal D2cc were 2.8 (2.5-3.7) Gy with RR and 3.2 (2.7-3.8) Gy with GP. The median bladder D2cc was 4.9 (4.5-6.3) Gy with RR and 4.8 (3.9-5.4) Gy with GP. The Wilcoxon signed-rank test revealed that rectal doses were significantly lower with RR (P = 0.02), whereas bladder doses were significantly higher with RR (P < 0.001). Analysis of the correlation between the number of gauze pieces and the difference in rectal D2cc between GP and RR using Pearson's distribution revealed no significant correlation (R = -0.20, P = 0.22), as well as bladder D2cc between GP and RR also revealed no significant correlation (R = -0.20, P = 0.22). The number of gauze pieces did not necessarily correlate with a reduction in the rectal and bladder dose. In conclusion, rectal D2cc was lower with RR in image-guided brachytherapy for cervical cancer, whereas bladder D2cc was higher with RR than with GP.