Reconstruction points of intrauterine applicator in intracavitary brachytherapy for cervical cancer
10.3760/cma.j.cn113030-20231229-00219
- VernacularTitle:宫颈癌腔内近距离放疗中宫腔管的重建点研究
- Author:
Yongfu FENG
1
;
Shaojun CHEN
;
Yusong LONG
;
Junwen TAN
;
Xiantao HE
;
Gang LI
;
Chengjun FENG
;
Zhanyu WANG
Author Information
1. 柳州市工人医院肿瘤放射治疗室，柳州 545005
- Keywords:
Uterine cervical neoplasms;
Intracavitary brachytherapy;
Intrauterine applicator;
Reconstruction deviation;
Dosimetry
- From:
Chinese Journal of Radiation Oncology
2024;33(9):825-832
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To evaluate the effect of different reconstruction points of intrauterine applicator on the source dwell positions and plan dosimetry in intracavitary brachytherapy for cervical cancer.Methods:Clinical data of 43 patients with cervical cancer who had completed radical radiotherapy in Liuzhou Workers' Hospital from May 2020 to October 2022 were retrospectively analyzed. Among 43 patients, aged 32-79 years, 40 cases were diagnosed with squamous carcinoma and 3 cases of adenocarcinoma. All patients received external irradiation for 50.4 Gy / 28 fractions and CT-guided intracavitary brachytherapy (45° intrauterine applicator) was 36 Gy / 6 fractions. Brachytherapy was performed by using Fletcher applicator, the curvature of intrauterine applicator were 15°, 30°and45°. Two sets of brachytherapy plans were simulated for each patient. One set of plans extracted the simulated CT positioning images and the original plan of the patient's brachytherapy. The reconstruction point of the curved part of the 45° intrauterine applicator was adjusted to slice-by-slice reconstruction. The plan was optimized to meet clinical requirements according to the prescription, which was called the slice-by-slice group. In the other set of plans, slice-by-slice group was used as a template. The reconstruction points of the curved section of the 45° intrauterine applicator were adjusted to 1, 3, 5, and 7, without modifying the applicator weights and other parameters, which was called the average group 1, 3, 5 and 7. The deviation analysis of 15°, 30° and 45° intrauterine applicator with different number of reconstruction points was carried out, the reconstruction deviation of 45°, 30° and 15° intrauterine applicator at different reconstruction points was compared. Paired-sample t-test or Wilcoxon signed rank test were used to compare the differences in high-risk clinical target volume (HR-CTV) D 50%, D 90%, D 100%, V 100%, V 150%, V 200% and conformity index (CI) as well as D 2 cm3, D 1 cm3 and D 0.1 cm3 in bladder, rectum, and small intestine between two groups of 45° intrauterine applicator. Results:The reconstruction deviation in the average group was mainly from the vertical direction of the 45° intrauterine applicator. The mean reconstruction deviations of 45° (1, 3, 5, 7 reconstruction points), 30° (1, 3, 5 reconstruction points) and 15° (1, 2 reconstruction points) were 1.30 mm, 0.32 mm, 0.14 mm and 0.08 mm; 0.57 mm, 0.14 mm and 0.06 mm; 0.14 mm and 0.06 mm, respectively. There was no significant difference in the parameters of high-risk clinical target volume (HR-CTV) in the slice-by-slice group compared with the average group 5 and 7 (all P>0.005), and no significant difference was found between the average group 5 and 7 (all P>0.005). There were no statistically significant differences in bladder and rectum doses between the slice-by-slice group and the average groups or within the average groups (all P>0.005). The parameters of small intestine in the slice-by-slice group were higher than those of the average group 1, the difference was statistically significant ( P=0.002,<0.001,<0.001). The dose of small intestine in the slice-by-slice group was not statistically significant compared with those in the average group 5 and 7 (both P>0.005). The dose of small intestine in the average group 5 was not statistically significant compared with that in the average group 7 ( P>0.005). The small intestine dose deviations of D 0.1 cm3, D 1 cm3 and D 2 cm3 in the average groups at 1 reconstruction point were 2.41%±1.70%, 1.95%±1.27% and 1.71%±1.10%, respectively. Conclusion:The number of reconstruction points is recommended to be no less than 1, 3 and 5 of the curved part of the 15°, 30°and 45° Fletcher intrauterine applicator, respectively, during intracavitary brachytherapy for cervical cancer.
