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A scatter correction method for dual-energy digital mammography: Monte Carlo simulation.

PURPOSE
To develop a novel scatter correction method without additional patient dose for dual-energy digital mammography (DEDM) to reduce scatter's impacts and enhance microcalcification detectability in dual-energy X-ray subtraction image.


METHODS
Combining scatter radiation is lower spatial frequency component and calcifications are sparsely distributed in digital mammogram, we develop a new scatter correction strategy. First, an adaptive sampling scheme is presented to find possible noncalcification (zero calcification) pixels. Then the maximum likelihood expectation maximization (MLEM) algorithm is applied to evaluate initial scatter surface. The accurate scatter radiation of sampling pixels is obtained by solving dual-energy computational formula with zero calcification constraint and scatter surface constraint.


RESULTS
After scatter correction, the scatter-to-primary ratio (SPR) of wedge phantom is reduced from ~36.0% to ~3.1% for low-energy (LE) image and ~29.6% to ~0.6% for high-energy (HE) image. For step phantom, the SPR is reduced from ~42.1% and ~30.3% to ~3.9% and ~0.9% for LE and HE image, respectively. The calcification contrast-to-noise ratio is improved by two orders of magnitudes in calcification images.


CONCLUSIONS
The proposed method shows an excellent performance on scatter reduction and calcification detection. Compared with hardware based scatter correction strategy, our method need no extra exposure and is easy to implementation.