X-ray Attenuation Measurements of a Fibrous Breast Tissue Phantom and X-ray Contrast Measurements with Various Plastics

Conventional diagnostic x-ray imaging modalities exploit x-ray linear attenuation coefficient differences (µ) of human tissues (i.e., tissues attenuate x-rays differently). The largest µ is between bone and ‘soft’ tissues. Clinical studies and µ measurements conducted over the past few decades indicated that dense (or fibrous) and cancerous human breast tissues have similar x-ray attenuation properties hindering accurate diagnosis and screening of breast cancer. Higher contrast was demonstrated by x-ray scattering experiments relying on histological differences between normal / malignant tissues and wave-like nature of x-rays. A silicon x-ray detector and an integrated x-ray tube (with tungsten target) and polycapillary x-ray lens unit were used to measure µ of a resin-based breast tissue phantom. Fiberglass resin was mixed with NaCl to match reported mean µ values of fibrous/tumor breast tissues. The resin-salt mixture µ values were measured at tungsten L-shell x-ray and bremsstrahlung energies. Measured µ values were in the 1.1 to 7.9 cm^-1 range for 15.5 down to 8.3 keV photon energies. Measured values of µ of 1.4, 1.1, and 1.0 cm^-1 at the 15, 17, and 19 keV photon energies were within the reported µ values for tumor and fibrous breast tissues at 17 and 19 keV energies, and ~11% lower than minimum µ of breast tumor at 15 keV. Plastics were also evaluated for contrast with favorable results.