Prospective comparison of rectal dose reduction during intracavitary brachytherapy for cervical cancer using three rectal retraction techniques

Publication date: Available online 16 April 2016
Source:Brachytherapy
Author(s): Iwa Kong, Sachi Vorunganti, Malti Patel, Thomas Farrell, Emilia Timotin, Sean Quinlan-Davidson, Greg Pond, Ranjan Sur, Robert Hunter
PurposeTo compare three rectal retraction methods on dose to organs at risk, focusing on rectal dose, in cervix cancer patients treated with high-dose-rate intracavitary brachytherapy.Methods and MaterialsA prospective study was conducted on patients with cervical carcinoma treated with chemoradiotherapy, including external beam radiation and four fractions of high-dose-rate intracavitary brachytherapy prescribed to Point A using a ring and tandem applicator under conscious sedation. Rectal retraction methods included: a rectal retractor blade (RR), vaginal gauze packing (VP), and a tandem Foley balloon (FB). All three methods were used in all patients. The RR was used first, and the following applications were randomly assigned to VP or FB. CT planning was used to calculate D2cc for rectum, sigmoid, small bowel, and bladder. The Wilcoxon signed rank test was used to determine if the median dose differences between methods were statistically significant.ResultsIn these 11 patients, median dose (min, max) in cGy to the rectum using RR, FB, and VP was 131 (102, 165), 199 (124, 243), and 218 (149, 299), respectively. The RR demonstrated lower median intrapatient doses to rectum compared with FB and VP (−55 cGy; p = 0.014 and −76 cGy; p = 0.004, respectively). The RR also resulted in lower sigmoid doses. No differences in dose were observed between the VP and FB methods.ConclusionThe rectal retractor significantly reduced the dose to rectum and sigmoid compared with FP and VP. In patients treated under conscious sedation, the RR method provides the best rectal sparing. There were no significant differences in dose observed between the FB and VP techniques.



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