In-line Phase Contrast Mammography, Phase Contrast Digital Breast Tomosynthesis and Phase Contrast Breast Computed Tomography with a Dedicated CT Scanner and a Microfocus X-ray tube: Experimental Phantom Study

We performed laboratory investigations of the image quality for 2D (digital mammography, DM) and 3D (digital breast tomosynthesis, DBT, and computed tomography, CT) in-line phase contrast imaging dedicated to the breast. We employed the cone-beam, microfocus computed tomography scanner developed in-house. Planar imaging tests were carried out with BR50/50 and PMMA test objects, at tube voltages of 60 kV, 80 kV and 100 kV. CT volume images, acquired at 80 kV at dose levels comparable to two-view mammography (mean glandular dose 4 mGy), as well as at 120 kV, were reconstructed from phase contrast projection images as well as from corresponding phase retrieved projection images (Paganin’s algorithm). We assumed 3D spatial uniform distribution of the ratio δ/β of the X-ray optical coefficients of the sample material, at the effective energy of the X-ray beam. In 2D imaging, all phantom details showed higher contrast after phase retrieval. In particular, contrast-to-noise ratio between a simulated mass and phantom background in phase retrieved images resulted up to 6.5 times than for absorption-based images. CT and DBT phase retrieval images of a homogeneous 50/50 test object at 120 kV produced higher signal-to-noise ratio of microcalcifications than in phase contrast DBT and CT of the same object, at the same glandular dose. In CT reconstructed volume images, microcalcifications down to 0.230–0.290 mm size presented an increased visibility after phase retrieval, in a two-components 50/50 breast phantom. For the first time, the advantages of in-line phase imaging in microfocus breast imaging have been shown with one setup for all techniques (DM, DBT and breast CT). These results motivate further research on in-line phase contrast 2D and 3D imaging of the breast with a microfocus X-ray tube for potential application in the clinic of in-line phase contrast DM, DBT and breast CT at dose levels comparable with corresponding attenuation-based exams.