Optimization of X-Ray Spectra in Medical Sterilization Accelerator through MCNP

Abstract

A Bremsstrahlung converter for medical apparatuses sterilization has been designed using tantalum and stainless-steel frame for a high energy electron accelerator operating at an incident electron energy of 7.5 MeV. Optimization of the x-ray spectra of the converter is investigated in this paper by adding a beam hardening filter from copper, aluminum, and stainless steel. The MCNP code is used to simulate the particle transport through the converter design. To survey the effect of each filtered spectra, angular dose distribution in the air is measured at radial distances of 50, 75, and 100 cm from the tantalum for the angle of 0° to 90°. A comparison between the unfiltered and the filtered spectra shows a marked decrease in low energy photon intensity up to the energy of 100 keV by all three filter materials with a greater reduction and hardening when combining the filter materials. These findings result in the angular dose distribution of the produced x-ray having a lower intensity at closer radial distances to the target due to the decreased intensity of x-rays with low energy, denoting a better dose homogeneity over the irradiated material.