Design of a drum-shaped applicator through Monte Carlo simulation for breast intraoperative radiotherapy
10.3760/cma.j.cn113030-20210304-00087
- VernacularTitle:使用蒙特卡罗模拟方法设计乳腺癌术中放疗的鼓形施照器
- Author:
Pan MA
1
;
Minghui LI
;
Chuanmeng NIU
;
Xin XIE
;
Min MA
;
Jianrong DAI
Author Information
1. 国家癌症中心/国家肿瘤临床医学研究中心/中国医学科学院北京协和医学院肿瘤医院放疗科 100021
- Keywords:
Monte Carlo simulation;
Drum-shaped applicator;
Breast neoplasms/intraoperative radiotherapy
- From:
Chinese Journal of Radiation Oncology
2021;30(6):587-591
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To design a drum-shaped applicator through Monte Carlo simulation for breast intraoperative radiotherapy.Methods:Applicator designing process is as follows: first, determined the shape of the applicator based on the geometric characteristics of the breast tumor bed closed to the chest wall; second, calculated the scattering angle and dose rate of the electron beam after passing through a series of scattering foils of different thicknesses to determine the thickness of the scattering foil; thrid, modeled the layer according to the applicator′s geometric characteristics where modulator located, and designed the modulator through the relationship between the geometric characteristics of the layer and the surface dose of the applicator. EGSnrc/BEAMnrc and EGS4/DOSXYZ were employed to model the head of the Mobetron, the layer, the applicator, and to calculate the dose distributions.Results:The applicator has two components. The upper component is a 3cm-diametre cylindrical collimator with 0.5cm wall made of 0.3cm steel and 0.2cm water equivalent material (WEM), a 0.13cm-foil made of tansgen. The lower component is a 4cm-diametre drum made of 0.2cm WEM and a 0.14cm maximum thickness hill-shaped modulator made of steel. When the energy of electron beam was 12MeV, the dose rate was about 90.44 cGy/min, and the depth of the 50% isodose curve was 1cm.Conclusion:The applicator is successfully designed, and can obtain a drum-shaped dose distribution.
