MCNP simulation of X-ray beam for a 15 MV medical linear accelerator

BackgroundThe application of high-energy medical electron accelerators in the radiotherapy becomes more and more widespread. Study of the radiation source and shielding of high-energy medical electron accelerators has been the focus of attention.PurposeThis study aims to simulate 15 MV X-ray beam of Clinac 23EX medical linear accelerator by using Monte Carlo method.MethodsFirst of all, a fine geometric model of the accelerator head in X-ray mode was constructed according to the material composition and geometric dimensions of the internal parts of the head provided by the manufacturer. Then the Monte Carlo N-Particle Transport Code (MCNP) software was applied to the calculation of the percentage depth dose (PDD) curves and profile curves of the X-ray beam under different irradiation fields. Comparisons of those results with that of measured results at the same conditions in the three-dimensional (3D) water model were performed. In addition, the effects of different components on the X-ray energy spectrum and