Abstract

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Title:: Monte Carlo simulation of Varian Trilogy linear accelerator 6 MV photon treatment head

Author(s):: SONG Bingwen; PAN Jiannan; WU Siyu; ZHU Fengying; LIANG Jiale; Department of Radiation Oncology, Shunde Hospital of Southern Medical University, Foshan 528300, China

Keywords:: ; Keywords: linear accelerator; Monte Carlo simulation; MCNP5; percent depth dose; lateral dose distribution

Abstract:: Abstract：Objective To construct an accurate Monte Carlo model of Varian Trilogy linear accelerator 6 MV photon treatment head for dose calculation. Methods The treatment head model was constructed using the MCNP5 package of Monte Carlo code according to the geometric parameters and material parameters of the components in linear accelerator treatment head. Over 20 accelerator components were defined in MCNP5. A water tank model with a size of (50×50×50) cm3 was used to calculate the percent depth dose and lateral dose distribution at field sizes of (5×5), (10×10), (20×20) and (40×40) cm2, respectively, with treatment head model at source skin distance=100 cm. The differences between the simulated results and the actual measured values were analyzed to determine the accuracy of the treatment head model. Results The statistical errors of all MCNP5 calculations were less than 5%. The difference between the calculated and measured values of the percent depth dose was less than 2%, and the maximum difference of the lateral dose distribution was no larger than 3%. Conclusion The good agreement between Monte Carlo simulations and measurements proves the accuracy of the treatment head model. Therefore, the treatment head model can be used for further dose calculation and radiation protection research.