Abstract

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Title:: Monte Carlo simulation of proton beams and investigation on ripple filters

Author(s):: KANG Yuehang1; 2; 3; SHENG Yinxiangzi1; 2; ZHAO Jingfang1; 2; ZHANG Qing2; 4; 1. Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Shanghai 201321, China 2. Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai 201321, China 3. Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, China 4. Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Shanghai 201321, China

Abstract:: Objective To explore the effect of ripple filter structure on the broadening of proton beams. Methods Monte Carlo program FLUKAwas used to establish a proton beam model, and the model was verified. The situations that proton beams passed through triangular prism type (A-type) and pyramid type (B-type) ripple filters were simulated, and the simulation data when the ripple filter was used or not were compared. The simulation data included the width between 50% of the maximum dose of the beam entrance and 50% of the maximum dose of the distal beam (E50-D50), the width between 80% of the maximum dose of the beam entrance and 80% of the maximum dose of the distal beam (E80-D80) and the width between 80% of the maximum dose of the distal beam and 20% of the maximum dose of the distal beam (D80-D20). Results The difference of E50, E70 and D80 between the integral depth dose curve plotted according to the simulation value of 121.1 MeV proton calculated by the model and the actually measured integral depth dose curve was no more than 0.06 mm. The E50-D50, E80-D80 and D80-D20 broadened byA-type ripple filter was 0.80, 0.27 and 0.08 mm wider than those broadened by B-type ripple filter. Conclusion The Monte Carlo model of proton beams is proved to be reasonable, and the triangular prism type (A-type) ripple filter has better effect on broadening the proton beams.