Abstract: Objective To simulate the multi-leaf collimator of Varian linear accelerator using Monte Carlo method. Methods The
multi-leaf collimator model was established using the DYNVMLC module of BEAMnrc and validated by comparison of Monte
Carlo simulation and actual measurement results. Results The simulation results were well consistent with the actual
measurement results with a bias of less than 3%. Conclusion The multi-leaf collimator of Varian linear accelerator can be
successfully modeled using Monte Carlo method for analysis of the impact of the geometric properties of the multi-leaf
collimator on the dose distribution.