臨床マンモグラフィスペクトル下における3Dプリント材料の実効X線減弱係数の実験的決定

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.

An experimental framework was implemented to determine the effective X-ray attenuation coefficient (μ _eff ) 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 μ _eff were obtained from measurements on images and fitted to an empirical model yielding μ ₀ (attenuation at thickness tending to zero) and k (decay rate) to characterize beam hardening and scatter influences. 3D-reference material equivalences were evaluated based on μ _eff and μ ₀ .

Beam hardening and scatter reduced μ _eff 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 μ _eff 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 μ ₀ values preserving attenuation ranking and enabling derivation of equivalent glandular proportions.

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.