Novel Physical Heterogeneous Breast Phantom for X-Ray Phase Contrast Imaging

摘要

This study is aiming to investigate the contribution of phase contrast breast tomosynthesis, in image quality and detectability of mammographic findings, using a breast phantom within a highly heterogeneous background incorporating details that mimic various breast lesions. A physical phantom was constructed with complex background composed of egg white part and lard, mimicking a breast with 40% glandular-60% adipose tissue. Nylon spheres and CaCO3 specks simulating masses and microcalcifications respectively, were embedded into the mixture at different depths. Mammographic and tomosynthesis images of 44° acquisition arc were obtained, in phase contrast mode with two different object to detector distances of 50 and 150 cm. The experiments were performed using synchrotron radiation at 20 keV within the conventional mean glandular dose (MGD) range. Line contrast measured across two of the mammographic findings was used as evaluation metric, in order to assess quantitatively the detection of breast abnormalities and the image quality from the different modalities. Visual and quantitative assessment of the images acquired, showed that the increase of object to detector distance resulted in superior contrast and stronger edge enhancement for both low and high contrast features. Tomosynthesis images eliminated the overlapping effect and made the in-depth localization of structures possible. Specifically, in case of the low contrast features, the smallest sized mass was hardly detected in the 2D images while it can be well visualized in the BT tomograms. Results of this study showed that tomosynthesis phase contrast imaging is a promising technique that can be proved important for the detection of small details in breast screening and diagnosing.