Approximately 75% of the breast cancer biopsies performed after recommendations from diagnostic mammography are benign, making it clear that specificity for diagnostic mammography still needs significant improvements. A novel three-compartment breast (3CB) composition technique developed by Laidevant et al. seeks to improve the specificity of diagnostic digital mammography, but it is prone to estimate incorrect compositional estimates for patient lesions. The focus of this thesis was to further develop this three-compartment technique for clinical applications in dual-energy X-ray imaging modalities.
Three potential sources of error in the 3CB technique were studied: (1) attenuation coefficient differences in biological materials—for which 3CB is estimating compositional estimates—and their calibration equivalents, (2) nonuniformities in full-field digital mammography (FFDM) from X-ray source spectra, and (3) initial intensity I_0 differences between biological and calibration images. Initial developments for 3CB applications in digital breast tomosynthesis were also investigated, and these were in two areas: (1) dose measurements and estimates were made for high energy 3CB digital breast tomosynthesis (DBT) images and (2) derivation of potential variables of interest as predictors of breast thickness from raw DBT projections. Lastly, a novel technique for measuring body composition from 2D optical images to help monitor and maintain healthy body weight was investigated, which could potentially aid in monitoring adipose and muscular tissues to monitor and maintain a lean weight to reduce risk of cancer for postmenopausal women in low-resource settings.
To reduce error in the attenuation coefficient differences between biological and calibration materials, linear mappings were created using bovine and chicken phantoms. This linear mapping corrected negative 3CB compositional estimates in a population study. To reduce error in nonuniformities in FFDM source spectra, polynomial flat-fielding models were created. These reduced nonuniformities to at or below imaging noise levels. To reduce I_0 differences between biological and calibration images, two I_0 correction models made it possible to obtain similar log-signal values between breast and calibration images.
To make the 3CB applicable to DBT, two areas were investigated. Firstly, dose measurements and estimates were made for HE 3CB DBT images. It was found that a copper filter of 0.4064 mm (16 mils) seems to be optimal in terms of meeting dose requirements, availability, and CNR. In addition, imaging at 71 mAs seems to optimize CNR while satisfying dose requirements. Secondly, investigations sought to derive potential variables of interest as predictors of breast thickness from raw DBT projections. It was found that variables derived from sinograms could be potentially useful in estimating breast thickness from raw DBT projections.
The last topic discussed in this thesis focused on developing a novel body composition technique from optical images. This proof-of-concept study showed that it may be possible to determine fat mass index, fat-free mass index, and percent-fat from 2D optical images.
Two of the three major works in this study advanced the 3CB imaging technique to become more clinically practical in dual-energy absorptiometry applications. The last focus of this thesis may make it easier to monitor body composition in low-resource settings.