Comparison of intracavitary brachytherapy and stereotactic body radiotherapy dose distribution for cervical cancer

Abstract

Purpose: To compare the dose distribution characteristics of stereotactic body radiotherapy (SBRT) with intracavitary high-dose-rate (HDR) brachytherapy in patients with cervical carcinoma.

Methods and materials: HDR intracavitary brachytherapy treatment plans for 11 women with cervical carcinoma were evaluated in this analysis. The total HDR brachytherapy dose was 28Gy given in four fractions. HDR brachytherapy was delivered with the microSelectron HDR therapy unit (Nucletron B. V., Veenendaal, The Netherlands). SBRT plans for each patient were generated with MultiPlan for CyberKnife Robotic Radiosurgery System (Accuray Inc., Sunnyvale, CA). The dose distributions, dose-volume histograms, and maximum dose points of the target and critical organs were recorded for both plans.

Results: SBRT yielded significantly better target coverage; the median target coverage for the 100% isodose line was 50.7% for HDR brachytherapy plans, whereas it was 99.1% for SBRT plans. The dose distributions for critical organs were similar in both types of plans. The exceptions were the 25% isodose being significantly better in brachytherapy plans for rectum, and the 100% isodose exposure being higher in brachytherapy plans for rectum, bladder, and sigmoid colon. Some significant differences were also found in maximum doses received by a 2-cc volume of bladder in favor of SBRT plans. In addition, maximum bone marrow doses were significantly higher in SBRT plans.

Conclusion: SBRT plans achieved better target coverage and better dose distributions to critical organs except bone marrow compared with HDR brachytherapy plans in patients with locally advanced cervical cancer.