A preliminary study of Bragg peak broadening by using mesh-stacked porous structure in scanning particle beam
10.3760/cma.j.cn113030-20231031-00152
- VernacularTitle:应用网格堆叠结构展宽粒子束流布拉格峰的初步研究
- Author:
Sixue DONG
1
;
Jiazhou WANG
;
Yinxiangzi SHENG
;
Weigang HU
Author Information
1. 复旦大学附属肿瘤医院放射治疗中心，复旦大学上海医学院肿瘤学系，上海市放射肿瘤学重点实验室，上海市放射治疗临床医学研究中心，上海 200032
- Keywords:
Radiotherapy, particle;
Ripple filter;
Bragg peak broadening;
Monte Carlo simulation
- From:
Chinese Journal of Radiation Oncology
2024;33(9):833-839
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To develop and validate a structure for broadening the Bragg peak to improve the efficiency and conformality of particle radiotherapy.Methods:Techniques of random stacking and regular stacking were employed to fabricate the mesh-stacked porous structure (MPS). In each layer of the grid, the thickness, line width and spacing were set at 0.1 mm, 0.1 mm and 0.5 mm, respectively, resulting in a total size of 10 cm ×10 cm. Monte Carlo code FLUKA was performed to simulate the transportation of 196 MeV/u carbon ion beam and a 105 MeV proton beam through the MPS. Dose distribution, fluence homogeneity, and modulation stability of the modulated beams were evaluated. Moreover, the modulation effect of MPS in clinical radiotherapy plans for nasopharyngeal carcinoma (63 Gy in 21 fractions), lung cancer (77 Gy in 22 fractions) and prostate cancer (70.4 Gy in 16 fractions) was also evaluated, respectively.Results:The MPS was capable of broadening the Bragg peak width by 1.73 mm for proton beams and 2.95 mm for carbon ion beams. For different entrance positions, regular stacking of more than 10 layers could reduce the modulation power difference of MPS to within 5%. For MPS with 30 layers of regular stacking, the modulated fluence homogeneity could achieve a value of less than 3% by transporting 18 cm distance in air. When comparing to the clinically used ripple filters, MPS reduced the isocenter spot size of proton beams by 0.91 mm. In the comparison study of the treatment plan for nasopharyngeal carcinoma, the use of MPS could shorten the treatment time by 213 s (37%) and reduce the maximum dose to the brainstem by 3.28 Gy (7.5%).Conclusions:MPS effectively broadens the Bragg peak of particle beams and improves the efficiency of clinical radiotherapy. Regularly stacked MPS demonstrates robust modulation stability, and the modulated beam achieves relatively well fluence homogeneity, making it a promising clinical application for closer to the patients and reducing lateral scattering.
