Evaluation of X-ray Attenuation Characteristics of 3D Printed Thermoplastic Slabs for Phantom Replacement Application

This study quantitatively investigated the attenuation characteristics of 3D printed thermoplastic materials under electromagnetic radiation in the diagnostic energy range to evaluate their feasibility as substitutes for the conventional phantom material, polymethyl methacrylate (PMMA). Slabs fabricated from polylactic acid (PLA) and acrylonitrile–butadiene–styrene (ABS) were examined at equivalent beam energies corresponding to tube potentials of 50, 70, and 100 kVp, with thicknesses of 5, 10, and 15 mm and infill densities of 20%, 60%, and 100%. Both experimental measurements and Monte Carlo simulations using MCNP 6.3 were performed. The average discrepancy between simulation and experiment was within 2.3%, indicating excellent agreement. Compared with PMMA, the mean attenuation differences for PLA and ABS were 3.7% and 8.8%, respectively. The penetrated dose increased linearly as the infill density decreased due to a reduction in effective density caused by higher porosity. PLA exhibited attenuation behavior nearly identical to PMMA because of its similar density and effective atomic number, which governs the electromagnetic interaction behavior, whereas ABS showed higher penetration, suggesting potential use as a lightweight structural support material. These results demonstrate that 3D printed thermoplastics provide sufficient quantitative reliability to serve as alternative phantom materials and can be effectively applied to patient-specific phantom fabrication and quality assurance (QA) or quality control (QC) procedures in diagnostic and therapeutic imaging systems.