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Phys Med Biol. 2019 Jul 1. doi: 10.1088/1361-6560/ab2df1. [Epub ahead of print]

Image reconstruction for interrupted-beam X-ray CT on diagnostic clinical scanners.

Author information

1
Radiology, NYU School of Medicine, 650 First Ave., Second Floor, New York, New York, 10016, UNITED STATES.
2
Department of Radiology, Mayo Clinic, Rochester, UNITED STATES.
3
Siemens Healthineers, Erlangen, GERMANY.
4
Siemens Healthineers, Malvern, Pennsylvania, UNITED STATES.
5
Radiology, New York University School of Medicine, New York, New York, UNITED STATES.
6
Harvard Medical School, Boston, Massachusetts, UNITED STATES.
7
Memorial Sloan Kettering Cancer Center, New York, New York, UNITED STATES.

Abstract

Low-dose X-ray CT is a major research area with high clinical impact. Compressed sensing using view-based sparse sampling and sparsity-promoting regularization has shown promise in simulations, but these methods can be difficult to implement on diagnostic clinical CT scanners since the X-ray beam cannot be switched on and off rapidly enough. An alternative to view-based sparse sampling is interrupted-beam sparse sampling. SparseCT is a recently-proposed interrupted-beam scheme that achieves sparse sampling by blocking a portion of the beam using a multislit collimator. The use of a multislit collimator necessitates a number of modifications to the standard compressed sensing reconstruction pipeline. In particular, we find that SparseCT reconstruction is feasible within a model-based image reconstruction framework that incorporates data fidelity weighting to consider penumbra effects and source jittering to consider the effect of partial source obstruction. Here, we present these modifications and demonstrate their application in simulations and real-world prototype scans. In simulations compared to conventional low-dose acquisitions, SparseCT is able to achieve smaller normalized root-mean square differences than tube-current reduction at larger dose reduction levels. In prototype experiments, we successfully apply our reconstruction modifications and maintain image resolution at the quarter-dose reduction level. The SparseCT design requires only small hardware modifications to current diagnostic clinical scanners, opening up new possibilities for CT dose reduction.

KEYWORDS:

compressed sensing; interrupted-beam CT; low-dose CT

PMID:
31258151
DOI:
10.1088/1361-6560/ab2df1

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