X-Ray Attenuation Measurements of a Breast Tissue Phantom

Conventional diagnostic x-ray imaging modalities exploit linear attenuation coefficient differences (Δµ) among human tissues. The largest Δµ is between bone and so-called 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 and malignant tissues and wave-like nature of x-rays. A silicon x-ray detector and an integrated x-ray tube and polycapillary x-ray lens unit were used to measure µ and scattering properties of a resin-based breast phantom material. Only x-ray attenuation measurements are reported here. Resin was mixed with salt (NaCl) to increase its µ and bring it closer to that of dense/cancerous breast tissues. Measured µ of resin-salt mixture was in the 0.022 mm^-1 to 0.41 mm^-1 range corresponding to 17.5 keV down to 9.6 keV photon energy range. Values for 15 and 17 keV photons were ~70% and ~60% smaller than reported µ of dense breast and resin, respectively. These results point to misalignment and low-angle x-ray scatter reduction problems.