Session Item

Rectal complications are common in radiotherapy for cervical cancer and correlates with rectal dose. Vaginal gauze packing (VP) and rectal retractor (RR) are widely used for rectal dose reduction in high dose rate brachytherapy. The purpose of this study is dosimetric comparison of these two methods in 3D image-guided adaptive brachytherapy.

We retrospectively analyzed 33 patients with cervical cancer who treated with definitive radiotherapy including intracavitary brachytherapy, which was performed with VP in first one or two fractions and with rectal RR in subsequent fractions. We extracted two fractions for each patients: one fraction with VP and a next fraction with RR and compared dose volume parameters. 33 fractions each in VP group and RR group were analyzed. Treatment planning was prescribed 6 Gy to point A initially, and then manually optimized to reduce dose to organs at risk (OAR) and ensure coverage of the target. Dose to 90 % (D90) of high-risk CTV (CTV_HR), dose to point A and dose to 2.0 cc (D_2cc) for OAR (bladder, rectum, sigmoid and small bowel) were collected from planning CT. The significance of differences of parameters were evaluated using paired t-tests.

There were no significant difference between VP vs. RR in D90 of CTV_HR (mean 750.2 cGy vs. 770.3 cGy p=0.2061). Dose to point A were significantly higher in VP (mean 622.1 cGy vs. 592.4 cGy, p=0.0310). D_2cc for the rectum (mean 392.8 cGy vs. 440.3 cGy, p=0.0149), D_2cc for the sigmoid (mean 415.7 cGy vs. 528.5 cGy, p<0.0001) and D_2cc for the bladder (mean 576.0 cGy vs. 827.6 cGy, p<0.0001) was significantly lower in VP. Significant differences were not found between VP vs. RR in D_2cc for the small bowel (mean 488.4 cGy vs. 486.4 cGy, p=0.9724). 

Our results show that VP reduces the dose to rectum, sigmoid and bladder compared with RR without impairing dose to CTV or point A.