Assessment of Transmission Factors and Shielding Requirements for Lead, Concrete and Iron in PET Imaging Environments

Abstract

Positron Emission Tomography (PET) facilities require tailored radiation shielding because of the highly penetrating 511 keV annihilation photons and the increased construction costs associated with overly conservative designs. In many low-resource settings, reliance on Monte Carlo–based calculations further limits the feasibility of establishing PET services. This study aims to assess transmission factors and determine shielding requirements for PET facilities using a practical analytical approach, validated against published Monte Carlo–derived reference data. A certified architect developed a complete PET facility layout in compliance with international architectural and radiation safety standards. Based on this layout, shielding requirements for lead, Iron, and concrete were calculated using standard attenuation equations and validated through comparison with transmission data published by the American Association of Physicists in Medicine (AAPM). The analytical method yielded shielding thicknesses of 0.089–0.81 cm for lead, 0.20–1.87 cm for Iron, and 0.98–8.91 cm for concrete, all of which complied with safety limits and were generally lower than corresponding Monte Carlo–based recommendations. These findings indicate that analytically derived designs, when applied to a realistic architectural layout, can achieve regulatory compliance while reducing the potential for unnecessary over-shielding. The proposed approach offers a reliable and accessible alternative for institutions—particularly in low-resource regions—by reducing computational complexity, while recognizing that more complex geometries and scatter conditions may still require Monte Carlo–based analyses.