Empirical and semi-empirical routine dose calculation algorithms have been commonly selected for the radiation treatment planning system
though they have limited accuracy for dose distribution calculation. The Monte Carlo method can precisely give the above distributions
but its long CPU time affects clinic application. This paper presents a calculation instance. Namely
based on the CT data of a patient’s head and neck
the Monte Carlo code is used to investigate the effect of different voxel sizes on the accuracy of dose distribution calculation and the computing time.