Characterization and applicability of low-density materials for making 3D physical anthropomorphic breast phantoms

• Published in: Radiation physics and chemistry (Oxford, England : 1993) England : 1993), 2019-11, Vol.164, p.108361, Article 108361
• Main Authors: Santos, J.C., Almeida, C.D., Iwahara, A., Peixoto, J.E.
• Format: Article
• Language: English
• Subjects: 3-D printers; 3D breast phantom; Adipose tissue; Anthropomorphism; Attenuation coefficients; Blood; Breast; Breast tissue–equivalent materials; Diagnostic systems; Equivalence; Image contrast; Image quality; Low density materials; Optimization; Photons; Polymethyl methacrylate; Quality assessment; Quality control; Skin; Systems analysis; Thickness measurement; Three dimensional printing; X ray spectra; X-ray spectrometry
• ISSN: 0969-806X; 1879-0895
• DOI: 10.1016/j.radphyschem.2019.108361

Test objects or phantoms are important tools for the optimization of dose and image quality in mammography. The main quality control protocols in mammography adopt homogeneous phantoms for image quality assessment, which generate images with unrealistic uniform background and do not consider the effect of breast anatomy on image quality. Realistic three-dimensional (3D) anthropomorphic phantoms with characteristic contrast of breast tissues are required to better evaluate clinical systems in terms of their intended diagnostic tasks. This work aims to characterize low-density materials by determining their linear attenuation coefficients, μ(E), and to evaluate their suitability as breast tissue–equivalent materials for printing 3D anthropomorphic breast phantoms. Incident and transmitted mammographic X-ray spectra through different material thicknesses were measured using a CdTe detector. Attenuation curves were derived for each photon energy, and the coefficients μ(E) were calculated between 10 and 20 keV for various materials. These coefficients were compared with data for breast tissues (glandular, adipose, skin, and blood) presented in the literature. Polymethyl methacrylate (PMMA) was used as the reference material to validate the methodology used in this work. The experimental μ(E) for PMMA agreed with the results of the literature, with an average relative difference of −0.44% and average relative uncertainty of ±3.70%. Among the analysed materials, 3D printing materials TangoBlackPlus™ and VeroClear™ (Stratasys, USA) presented the best glandular equivalency, with average percentage differences relative to the theoretical coefficients, μ(E), for glandular tissue of −0.36% and +1.85%, respectively. A urethane-based polymer (water simulant) was the material with the best adipose equivalency, showing an average relative difference in μ(E) of +3.39%. None of the studied materials was suitable to provide the photon attenuation equivalent to skin or blood. TangoBlackPlus™ and VeroClear™ presented similar attenuation to the glandular tissue when compared with results from reference data of ICRP 110. These materials can be suitable for 3D printing of glandular tissue in a breast phantom, while the urethane-based polymer might be used to fill the phantom as adipose tissue–equivalent material. •Materials for 3D breast phantoms were characterized.•Linear attenuation coefficients for these materials were obtained by X-ray spectrometry.•Two candidates for breast