| Mammography has been shown to be the most and only effective means of screening cancer. Because mammography is a projection x-ray modality and is inherently planar in its imaging representation, efficacy of breast cancer detection is limited by the effect of overlapping tissue, which may obscure or confuse diagnosis of otherwise visible lesions. Digital breast tomosynthesis (DBT) is a three-dimensional (3D) imaging modality and involves the acquisition of x-ray projection images while the tube is rotated through a limited angular range (<50 degrees) over the detector. The projection images are reconstructed into an imaging volume and are viewed in 1 mm thick slices oriented parallel to the detector plane. The presentation of imaging information in 3D allows the removal of overlapping tissue to improve lesion conspicuity. The total glandular dose for a single-view DBT study should be comparable to that of a standard screening mammogram (∼1.5 mGy for a 4 cm breast).;In recent years, a great deal of research has been devoted to DBT on a number of different prototype and commercial units. Currently, there are no widespread standards for DBT acquisition geometry or system settings. Subtleties in these imaging parameters, however, may have profound effects on image quality. To this end, a direct-conversion x-ray detector model and a DBT model were developed based on a cascaded linear systems assumption to investigate the effects of various imaging and system parameters, including acquisition geometry, glandular dose, and detector physics. The primary objective of this thesis is to investigate the physics involved in DBT, understanding the effects of artifact propagation through the imaging process and overlying tissue as a deterministic source of noise, as well as the application the CLSM for the optimization of advanced imaging techniques such as non-uniform angular dose distributions and contrast enhanced (CE) imaging.;First, a previously designed and validated CLSM for amorphous selenium (aSe) direct panel digital mammographic detectors and DBT systems was employed in order to understand the effect of a number physical processes. Characteristic DBT artifact spread and its propagation through DBT imaging chain was investigated as was the effect of overlapping tissue acting as a deterministic source of noise (structural noise).;Finally, the CLSM was modified to include the effect of structural noise on both DM and DBT imaging. A partially isocentric acquisition geometry was modeled to more directly match results garnered from a prototype system. Advanced techniques such as non-uniform angular dose distribution and CE imaging (for both DM and DBT applications) were studied. The modeled results were validated using experimental measurements from the prototype systems, comparing physical, Fourier domain metrics such as noise power spectrum (NPS), modulation transfer function (MTF), and DQE. Additionally, these techniques were optimized to produce maximum object detectability by implementing Fourier domain imaging metrics into a formulation of the ideal observer signal-to-noise ratio (SNR), which for a simple signal known exactly (SKE) background known exactly (BKE) detection task, is known as the detectability index, d'. |
