Towards a breast phantom: an evaluation of total mass attenuation coefficients for simulating breast tissues and pathologies

Mammography is currently the most widely recommended imaging modality for the diagnosis of breast cancer. However, due to the similar radiographic appearance of different breast tissues, high image quality is essential for accurate interpretation. To ensure the reliable reproduction of image patterns that allow for clear visualization of anatomical structures, performance tests are routinely conducted on mammographic systems using objects that simulate human tissue, commonly referred to as breast phantoms. This study presents the evaluation of 14 different candidate materials as tissue-equivalent substitutes, some of which are intended for 3D printing (polyethylene terephthalate glycol (PETG), acrylonitrile butadiene styrene (ABS), and polylactic acid (PLA)), while others are not (dental wax, beeswax, silicone, fiberglass, polyvinyl chloride (PVCF), and polyethylene terephthalate (PET)), in accordance with the reference compositions provided by the International Commission on Radiation Units & Measurements (ICRU) and the International Commission on Radiation Protection (ICRP). The tissues investigated include adipose tissue, glandular tissue, a composite breast tissue (50% adipose, 50% glandular), and skin. Additionally, pathological conditions such as invasive ductal carcinoma and both type I and type II microcalcifications were considered. The assessment was based on comparing the mass attenuation coefficients between the candidate materials and the reference tissues/pathologies over the energy range of 10 to 30 keV, typically used on mammographic images. The elemental compositions of the candidate materials were determined using energy-dispersive spectroscopy coupled with a scanning electron microscope. These compositions were then used to calculate the mass attenuation coefficients. In the quantitative analysis, the materials that showed a difference of up to ±10% in their attenuation coefficients relative to the attenuation characteristics of breast tissue were as follows: for adipose tissue, the most similar was PETG, followed by GPET, beeswax, and ABS; for glandular tissue, PLA was the only candidate with a difference of up to ±10%” (or “within ±10%”). For breast tissue, according to ICRU No. 44, the most similar was PLA, followed by PET; and for ICRP No. 89, the most similar was PET, followed by PETG and beeswax. Regarding pathologies, silicone exhibited attenuation characteristics most similar to those of invasive ductal carcinoma. None of the materials showed similarity to type I or type II microcalcifications. The results of this study demonstrate the proximity of each analyzed candidate to the various tissues present in the human breast. Furthermore, it facilitates the implementation of the Mammography Quality Control and Assurance Program at the national scale and provides an alternative for training professionals by enabling the creation of various structures of interest in a simulator.