Digital Tomosynthesis Mammography (DTM) is a promising modality that can improve breast cancer detection. DTM acquires low-dose mammograms at a number of projection angles over a limited angular range and reconstructs the 3D breast volume. DTM can provide depth information to separate overlapping breast tissues occurred in conventional mammograms, thereby facilitating detection of subtle lesions. In this work, we investigated the impact of the imaging parameters and reconstruction methods on the Z-axis resolution in DTM systems. The Z-axis resolution represents the ability of the DTM system to distinguish adjacent objects along the depth direction. A DTM system with variable image acquisition parameters was modeled. In this preliminary study, a computer phantom containing a high-density point object embedded in an air volume was used. We simulated a range of DTM conditions by generating an appropriate number of PV images in 3° increments covering a total tomosynthesis angle from ±15° to ±30°. The Simultaneous Algebraic Reconstruction Technique (SART) was used for reconstruction of the imaged volume from the noise-free projection data and the results were compared to those of back-projection method. Vertical line profiles along the Z-axis and through the object center were extracted from the reconstructed volume and the full-width-at-half-maximum (FWHM) of the normalized intensity profile was used to evaluate the Z-axis resolution. Preliminary results demonstrated that while the Z-axis resolution remains almost constant as a function of depth within a 5-cm-thick volume, it is strongly affected by the PV angular range such that the depth resolution improves with increasing total tomosynthesis angle. The depth resolution also depends on the reconstruction algorithm employed; the SART method is superior to the simple back-projection method in terms of depth resolution.

Date Published: 15 March 2007
PDF: 8 pages
Proc. SPIE 6510, Medical Imaging 2007: Physics of Medical Imaging, 65104A (15 March 2007); doi: 10.1117/12.713816

Published in SPIE Proceedings Vol. 6510:
Medical Imaging 2007: Physics of Medical Imaging
Jiang Hsieh; Michael J. Flynn, Editor(s)