Treatment plan optimization for intensity-modulated brachytherapy based on the conjugate gradient algorithm
10.3760/cma.j.cn112271-20240103-00004
- VernacularTitle:基于共轭梯度法的调强近距离放射治疗计划优化方法的研究
- Author:
Miao QI
1
;
Junyi LIU
;
Shijun LI
;
Yankui CHANG
;
Jieping ZHOU
;
Bing YAN
;
Yong CHENG
;
Aidong WU
;
Xi PEI
;
Xie XU
Author Information
1. 中国科学技术大学核科学技术学院，合肥 230001
- Publication Type:Journal Article
- Keywords:
Intensity-modulated brachytherapy;
Treatment plan optimization;
Conjugate gradient method
- From:
Chinese Journal of Radiological Medicine and Protection
2025;45(1):56-62
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the application of the conjugate gradient (CG) algorithm to treatment plan optimization for intensity-modulated brachytherapy (IMBT).Methods:The general Monte Carlo software TOPAS was utilized to simulate the 192Ir source of IMBT, and the unit dose contribution matrix was calculated. An objective function was established using the weighted least squares method and was solved using the CG algorithm to achieve optimized IMBT treatment plans. The optimization was validated using five clinical cervical cancer cases under modulation width 60°. The dose distributions of IMBT treatment plans under 45°, 60°, 90°, 120°, and 180° modulation widths were compared using the Wilcoxon test to determine the optimal IMBT treatment plan for cervical cancer treatment. Results:The CG algorithm successfully optimized IMBT treatment plans under modulation width 60° for five cases within 22.2 s on average. On the premise of sufficient target dose coverage, the average D2 cm 3 values of the bladder and rectum in IMBT treatment plans were 3.66 and 1.97 Gy, respectively, representing reductions of 0.54 and 0.69 Gy compared to traditional brachytherapy plans. For the five modulation widths, the D90% values of all IMBT treatment plans reached 6 Gy, without statistically significant differences ( P > 0.05). The average D2 cm 3 values of the bladder in IMBT treatment plans were significantly lower than those in the traditional brachytherapy plans( P<0.05), with modulation width 60° associated with the greatest reduction of 0.61 Gy. In contrast, the average D2 cm 3 values of the rectum under 45°, 60°, and 90° modulation widths decreased by 0.63, 0.54, and 0.45 Gy, respectively, compared to traditional plans, with statistically significant differences( P<0.05). Conclusions:The CG method enables rapid achievement of optimized IMBT treatment plans that meet clinical requirements, and modulation width 60° contributes to valid dosimetric optimization. This study can serve as a guide for the clinical implementation of IMBT.
