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Study of dose distortion and Bragg peak location correction in MRI-guided proton therapy
Deng Xiuzhen1,2, Li Xiufang3, Guo Mengya1,2, Gu Shuaizhe1,2, Liu Qi1,2, Chen Zhiling1,4
1Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; 2University of Chinese Academy of Sciences, Beijing 100049, China; 3Shanghai APACTRON Particle Equipment Co., Ltd, Shanghai 201800, China; 4Shanghai Advanced Research Institute Chinese Academy of Sciences, Shanghai 201210, China
AbstractObjective To analyze the influence of magnetic field on the proton beam delivery and dose distribution, and develop a correction method for the Bragg peak (BP) shift under the vertical magnetic field, providing reference for the dose calculation and beam delivery of MRI-guided proton therapy. Methods Monte Carlo (MC) simulation was used to study the dose distribution of the proton beam in the water phantom under the magnetic field. The BP location was corrected by the method of"angle correction+ energy correction", and the correction parameters were calculated by the analytical formula based on the simulation data. Results The magnetic field caused the dose distortion and shift of BP location. The shift degree was increased with the increase of field strength and initial energy. Compared with MC simulation, the result of calculating proton deflection in the air by the analytical method yielded a deviation within 0.2%. Based on the simulation data and calculation formulas, the correction parameters under different conditions could be calculated within 1s by using the MATLAB programming. The calculation results showed that the air layer with magnetic field, isocenter depth, irradiation direction exerted different influence on the correction parameters. After correction, the BP location was basically consistent with the expected (offset ≤0.2mm). Conclusions The BP shift under the vertical magnetic field can be effectively corrected by "the angle correction+ energy correction" method. The correction parameters under different conditions can be quickly and accurately calculated by the calculation formulas based on simulation data.
Deng Xiuzhen,Li Xiufang,Guo Mengya et al. Study of dose distortion and Bragg peak location correction in MRI-guided proton therapy[J]. Chinese Journal of Radiation Oncology, 2022, 31(2): 176-181.
Deng Xiuzhen,Li Xiufang,Guo Mengya et al. Study of dose distortion and Bragg peak location correction in MRI-guided proton therapy[J]. Chinese Journal of Radiation Oncology, 2022, 31(2): 176-181.
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2022, Vol. 31 
