Dosimetric comparison of rectal dose-reductive techniques in intra-cavitary brachytherapy for cervical cancer: A retrospective analysis

Abstract

Purpose Rectal complications in radiotherapy for cervical cancer can highly affect quality of life and correlate with rectal dose. Vaginal gauze packing (VP) and rectal retraction (RR) are widely used for rectal dose reduction in high-dose-rate brachytherapy. We aimed to perform a dosimetric comparison of these two methods for three-dimensional image-guided adaptive brachytherapy. Material and methods We retrospectively examined 50 patients with cervical cancer treated with definitive radiotherapy, including intra-cavitary brachytherapy, performed with VP and RR. We extracted two fractions for each patient: one fraction with VP and the next fraction with RR, and then compared dose-volume parameters. In total, 50 fractions each were analyzed in VP and RR groups. Dose to 90% (D 90 ) of high-risk clinical target volume (HR-CTV), and minimum dose to most exposed 2.0 cm 3 of other organs at risk (D 2cm 3 ) for the rectum and bladder were determined from planning computed tomography. Results There were no significant differences between VP and RR in D 90 of HR-CTV (mean: 7.479 Gy and 7.652 Gy, respectively, p = 0.172). The D 2cm 3 values for the rectum (mean: 4.234 Gy vs. 4.627 Gy, p = 0.008) and bladder (mean: 5.959 Gy vs. 6.690 Gy, p < 0.001) were significantly lower with VP compared with RR. Conclusions VP reduced the dose to the rectum and bladder when compared with RR without impairing the dose to CTV.