A general CT reconstruction algorithm for model-based material decomposition

Steven Tilley; Wojciech Zbijewski; Jeffrey H. Siewerdsen; J. Webster Stayman

doi:10.1117/12.2293776

9 March 2018 A general CT reconstruction algorithm for model-based material decomposition

Steven Tilley, Wojciech Zbijewski, Jeffrey H. Siewerdsen, J. Webster Stayman

Proceedings Volume 10573, Medical Imaging 2018: Physics of Medical Imaging; 105731E (2018) https://doi.org/10.1117/12.2293776
Event: SPIE Medical Imaging, 2018, Houston, Texas, United States

Abstract

Material decomposition in CT has the potential to reduce artifacts and improve quantitative accuracy by utilizing spectral models and multi-energy scans. In this work we present a novel Model-Based Material Decomposition (MBMD) method based on an existing iterative reconstruction algorithm derived from a general non-linear forward model. A digital water phantom with inserts containing different concentrations of calcium was scanned on a kV switching system. We used the presented method to simultaneously reconstruct water and calcium material density images, and compared the results to an image domain and a projection domain decomposition method. When switching voltage every other frame, MBMD resulted in more accurate water and calcium concentration values than the image domain decomposition method, and was just as accurate as the projection domain decomposition method. In a second, slower, kV switching scheme (changing voltage every ten frames) which precluded the use of traditional projection domain based methods, MBMD continued to produce quantitatively accurate reconstructions. Finally, we present a preliminary study applying MBMD to a water phantom containing vials of different concentrations of K₂HPO₄ which was scanned on a cone-beam CT test bench. Both the fast and slow (emulated) kV switching schemes resulted in similar reconstructions, indicating MBMD's robustness to challenging acquisition schemes. Additionally, the K2HPO4 concentration ratios between the vials were accurately represented in the reconstructed K₂HPO₄ density image.

Conference Presentation

Citation Download Citation

Steven Tilley, Wojciech Zbijewski, Jeffrey H. Siewerdsen, and J. Webster Stayman "A general CT reconstruction algorithm for model-based material decomposition", Proc. SPIE 10573, Medical Imaging 2018: Physics of Medical Imaging, 105731E (9 March 2018); https://doi.org/10.1117/12.2293776

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