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FLOYD CAREY E. Jr PhD; BAYDUSH, ALAN H. BSE; LO, JOSEPH Y. BSE; BOWSHER, JAMES E. PhD; RAVIN, CARL E. MD
Investigative Radiology: May 1993
Original Investigations: PDF Only
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RATIONALE AND OBJECTIVES.

An iterative maximum likelihood expectation maximization algorithm (MLEM) has been developed for scatter compensation in chest radiography.

METHODS.

The MLEM technique produces a scatterreduced image which maximizes the probability of observing the measured image. We examined the scatter content and the low-contrast signal-to-noise ratio (SNR) in digital radiographs of anatomical phantoms before and after compensation.

RESULTS.

MLEM converged to an accurate (6.4%RMS residual scatter error) estimate within 12 iterations. Both contrast and noise were increased in the processed images as iteration progressed. In the lung, contrast was increased 108% and SNR was improved by 10%. In the retrocardiac region, contrast was increased 180% while SNR decreased by 6%.

CONCLUSIONS.

This is the first report of a post-acquisition scatter compensation technique which can increase SNR. These results suggest that statistical estimation techniques can enhance image quality and quantitative accuracy for digital chest radiography.

© Lippincott-Raven Publishers.