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Proceedings Paper

Noise reduction in material decomposition for low-dose dual-energy cone-beam CT
Author(s): W. Zbijewski; G. Gang; A. S. Wang; J. W. Stayman; K. Taguchi; J. A. Carrino; J. H. Siewerdsen
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Paper Abstract

Purpose: Dual-energy cone-beam CT (DE-CBCT) is an emerging technology with potential application in diagnostic imaging and image-guided interventions. This paper reports DE-CBCT feasibility and investigates decomposition algorithms for maximizing low-dose performance for reconstruction-based DE decomposition. A framework of binary decision theory is used to examine the accuracy of DE decompositions obtained from analytical reconstructions of differentially filtered low-energy (LE) and high-energy (HE) data and from penalized likelihood (PL) reconstructions with differential regularization using quadratic and total variation penalties. Methods: Accurate DE-CBCT decomposition benefits from consideration of all system noise components. Filtered backprojection (FBP) reconstruction-based decomposition was investigated with differential filtering of LE and HE data. Penalized likelihood reconstruction-based decomposition with differential regularization was hypothesized to further improve low-dose performance, especially when coupled with regularization through a total variation edge preserving penalty that encourages piecewise smooth images. Performance of decomposition was assessed in terms of a binary hypothesis framework of sensitivity, specificity, and accuracy. Studies involved experiments on a DE-CBCT testbench, phantoms of variable material type and concentration, and cadavers (knee arthrography). Results: Studies support the overall feasibility of accurate, low-dose DE-CBCT at concentration down to 5 mg/ml (iodine), dose ~3-6 mGy, and accuracy of material classification ~90%. Reconstruction-based decomposition with quadratic PL performed comparably to FBP. PL with a total variation penalty provided edge preservation and piecewise smooth images that aided DE classification and achieved improved performance over FBP and quadratic PL, reaching accuracy of ~0.98 for 2 mg/mL iodine at 3.2 mGy, compared to approx. 0.9 for FBP and quadratic PL. Conclusions: Accurate material decomposition with DE-CBCT is feasible at low dose and benefits from a rigorous assessment of noise mechanisms among various reconstruction-based techniques. The work points to the potential for non-linear iterative reconstruction methods for high-quality decomposition at low material concentration and dose.

Paper Details

Date Published: 21 March 2013
PDF: 7 pages
Proc. SPIE 8668, Medical Imaging 2013: Physics of Medical Imaging, 866819 (21 March 2013); doi: 10.1117/12.2008431
Show Author Affiliations
W. Zbijewski, Johns Hopkins Univ. (United States)
G. Gang, Johns Hopkins Univ. (United States)
A. S. Wang, Johns Hopkins Univ. (United States)
J. W. Stayman, Johns Hopkins Univ. (United States)
K. Taguchi, Johns Hopkins Univ. (United States)
J. A. Carrino, Johns Hopkins Univ. (United States)
J. H. Siewerdsen, Johns Hopkins Univ. (United States)


Published in SPIE Proceedings Vol. 8668:
Medical Imaging 2013: Physics of Medical Imaging
Robert M. Nishikawa; Bruce R. Whiting; Christoph Hoeschen, Editor(s)

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