Evidence Hub

Estimation of backscatter factor in ISO-recommended phantoms for photon beams of different beam sizes using Monte Carlo simulations

Rohit Yadav, AK Bakshi, B K Sapra

Journal of Radiological Protection, 2026

Abstract

Abstract Backscatter factor (BSF) is a critical correction parameter in radiation dosimetry, accounting for dose enhancement due to photon scattering within irradiated media; however, systematic evaluations beyond the ISO slab phantom remain limited. In this work, BSFs were comprehensively estimated for all ISO-recommended phantoms—slab, cylindrical, pillar, and rod—over a photon energy range of 10 keV–2 MeV and multiple field sizes using the FLUKA Monte Carlo code with an air-kerma–based formalism. The results show a strong coupled dependence of BSF on photon energy and beam size, with a characteristic peak in the intermediate energy range (∼40–80 keV) and geometry-driven variations and field-size sensitivity—maximized in the slab phantom and minimized in the rod due to scattering volume constraints, while cylindrical and pillar phantoms exhibit intermediate behaviour. To extend these results to realistic irradiation conditions, a Python-based standalone tool was developed using PCHIP interpolation and fluence-weighted averaging to compute spectrum-averaged BSFs for ISO 4037 beams, diagnostic and therapeutic spectra, and user-defined spectra, demonstrating deviation within 0%–2.3% with published data. The study provides a BSF dataset across all ISO phantoms along with a validated computational framework, enabling improved accuracy in dosimeter calibration and determination of operational quantities such as H p (3) and H p (0.07). The Python-based standalone executable of…

Read the paper

Related studies

Go deeper in Evidence Hub

Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.

Open this study Sign up free