Experimental Determination of Effective X-ray Attenuation Coefficients of 3D-Printed Materials Under Clinical Mammography Spectra

ADRIÁN BELARRA^1*Irene Hernández-Girón²Julia Garayoa^1,3Luis Carlos Martínez^1,4Julio Valverde³María José Rot⁴Alejandro Ferrando^4,5Antonio Martín⁵Margarita Chevalier¹

• ¹Medical Physics, Radiology and Rehabilitation Department, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
• ²University College Dublin School of Physics, Dublin, Ireland
• ³Servicio de Protección Radiológica, Hospital Universitario Fundacion Jimenez Diaz, Madrid, Spain
• ⁴Servicio de Radiofísica Hospitalaria, Hospital Universitario 12 de Octubre, Madrid, Spain
• ⁵Unidad de Tecnologías Avanzadas en Diseño e Impresión 3D (UTADI 3D), Instituto i+12. Hospital Universitario 12 de Octubre, Madrid, Spain

Background 3D printing enables the fabrication of customized breast phantoms for image quality assessment in digital mammography (DM) and digital breast tomosynthesis (DBT). A major challenge is the absence of standardized, accessible methods to characterize the attenuation properties of 3D-printed materials under clinical DM/DBT spectra. Methods An experimental framework was implemented to determine the effective X-ray attenuation coefficient (μeff) of six 3D-printed polymers (PLA, PET, resin, ABS, ABS+, HIPS) and reference breast tissue-equivalent materials (CIRS plates simulating different breast glandular/adipose ratios (BR) and PMMA) using two commercial DM/DBT systems, with and without anti-scatter grid. Step-wedges (0.5–5.5 cm) were imaged across multiple kVp and filter settings. The μeff were obtained from measurements on images and fitted to an empirical model yielding μ₀ (zero-thickness attenuation) and k (decay rate) to characterize beam hardening and scatter influences. 3D-reference material equivalences were evaluated based on μeff and μ₀. Results Beam hardening and scatter reduced μeff with thickness, by 6–14% with grid and 12–28% without grid, with scatter contributing 47–76% of the reduction in no-grid acquisitions. No significant differences were observed between the two mammography systems. Based on μeff values, attenuation equivalences (within ±6%) were identified between 3D-printed and reference breast tissue-equivalent materials: PLA with BR 100/0; PET and resin with BR 70/30 and PMMA; ABS+ with BR 30/70 and BR 50/50. ABS and HIPS showed larger mismatches. The empirical model achieved excellent fits (R² > 0.99), with μ₀ values preserving attenuation ranking and enabling derivation of equivalent glandular proportions. Conclusion This framework demonstrates that routine clinical mammography systems can be used directly, without specialized instrumentation, to characterize 3D-printed materials as tissue surrogates. Several low-cost, widely available polymers were shown to reproduce breast tissue attenuation, supporting the local fabrication of anthropomorphic breast phantoms for realistic and clinically relevant image quality evaluation.