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We are developing a computerized technique to reduce intra- and interplane ghosting artifacts caused by high-contrast
objects such as dense microcalcifications (MCs) or metal markers on the reconstructed slices of digital
tomosynthesis mammography (DTM). In this study, we designed a constrained iterative artifact reduction method
based on a priori 3D information of individual MCs. We first segmented individual MCs on projection views (PVs)
using an automated MC detection system. The centroid and the contrast profile of the individual MCs in the 3D breast
volume were estimated from the backprojection of the segmented individual MCs on high-resolution (0.1 mm isotropic
voxel size) reconstructed DTM slices. An isolated volume of interest (VOI) containing one or a few MCs is then
modeled as a high-contrast object embedded in a local homogeneous background. A shift-variant 3D impulse response
matrix (IRM) of the projection-reconstruction (PR) system for the extracted VOI was calculated using the DTM
geometry and the reconstruction algorithm. The PR system for this VOI is characterized by a system of linear equations.
A constrained iterative method was used to solve these equations for the effective linear attenuation coefficients (eLACs)
within the isolated VOI. Spatial constraint and positivity constraint were used in this method. Finally, the intra- and
interplane artifacts on the whole breast volume resulting from the MC were calculated using the corresponding impulse
responses and subsequently subtracted from the original reconstructed slices.
The performance of our artifact-reduction method was evaluated using a computer-simulated MC phantom, as
well as phantom images and patient DTMs obtained with IRB approval. A GE prototype DTM system that acquires 21
PVs in 3º increments over a ±30º range was used for image acquisition in this study. For the computer-simulated MC
phantom, the eLACs can be estimated accurately, thus the interplane artifacts were effectively removed. For MCs in
phantom and patient DTMs, our method reduced the artifacts but also created small over-corrected areas in some cases.
Potential reasons for this may include: the simplified mathematical modeling of the forward projection process, and the
amplified noise in the solution of the system of linear equations.
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