- 作者：Dilini S. Pinnaduwage ; J. Adam Cunha ; Vivian Weinberg ; Devan Krishnamurthy ; Marc Nash ; I-Chow Hsu ; Jean Pouliot
- 关键词：Interfraction dosimetry ; HDR brachytherapy ; Cervical cancer ; Tandem&ndash ; ring
- 刊名：Brachytherapy
- 出版年：2013
- 出版时间：September-October, 2013
- 年：2013
- 卷：12
- 期：5
- 页码：487-494
- 全文大小：1037 K
Purpose
To evaluate the dosimetric impact of using one treatment plan for multiple fractions from a single tandem and ring applicator insertion of high-dose-rate brachytherapy for cervical cancer.Methods and Materials
Thirteen cervical cancer patients undergoing high-dose-rate brachytherapy were followed. Patients received the total dose from a single applicator insertion in two fractions, given with at least 6 hours apart within 24 hours. The treatment plan was based on a CT scan taken before the first treatment fraction. A second CT was obtained before the second treatment fraction. The co-registered image series were used to evaluate the dosimetric impact of using a single treatment plan for both fractions. Applicator and catheters were measured to quantify interfraction displacement.
Results
When the Day 1 plan was applied to the Day 2 images, high-risk clinical target volume (HR-CTV) coverage was reduced by as much as 17.4 percentage points. The mean decrease was 9.4?¡À?5.0 percentage points (p?<?0.0001). The rectum V75 increase was significant (p?=?0.03), whereas the bladder V75 increase was not significant (p?=?0.28). Volume changes in the HR-CTV contour from Day 1 to Day 2 were also observed (p?=?0.29). Maximum applicator and catheter displacements of 10-30 mm were seen, from Day 1 to Day?2.
Conclusions
When the Day 1 plan was used on the Day 2, the HR-CTV coverage decreased significantly (p?<?0.0001). Our study establishes the need for institutions to evaluate the necessity for replanning based on imaging obtained before each treatment fraction for their gynecologic brachytherapy techniques.