PHITS-based Monte Carlo analysis of stainless steel as a bremsstrahlung converter for electron beam dosimetry

Abstract

This study evaluates stainless steel 304 as a bremsstrahlung converter for a 2.5 MeV electron beam to improve penetration depth and moderate dose delivery for electron beam dosimetry, comparing its performance with copper and tantalum using PHITS-based Monte Carlo simulations. A cylindrical water phantom with a centrally sliced core, irradiated by a uniform disk source of monoenergetic electrons, was simulated to assess depth-dose distributions and spatial-energy fluence profiles. Spatial distributions showed photons penetrating deeper than electrons, which were mostly absorbed or backscattered by the converter. Depth-dose curves indicated comparable dose deposition across materials, with Tantalum yielding slightly higher doses due to greater bremsstrahlung efficiency. Fluence spectra confirmed photon dominance over secondary electrons in the cell nearest to the stainless steel converter. Overall, these findings highlight stainless steel 304 as a cost-effective alternative to high-Z materials for bremsstrahlung-based electron beam dosimetry.