An improved physics model for multi-material identification in photon counting CT

Xu Dong; Olga V. Pen; Zhicheng Zhang; Guohua Cao

doi:10.1117/12.2512525

1 March 2019 An improved physics model for multi-material identification in photon counting CT

Xu Dong, Olga V. Pen, Zhicheng Zhang, Guohua Cao

Author Affiliations +

Proceedings Volume 10948, Medical Imaging 2019: Physics of Medical Imaging; 109484O (2019) https://doi.org/10.1117/12.2512525
Event: SPIE Medical Imaging, 2019, San Diego, California, United States

Abstract

Photon-counting computed tomography (PCCT) with energy discrimination capabilities hold great potentials to improve the limitations of the conventional CT, including better signal-to-noise ratio (SNR), improved contrast-to-noise ratio (CNR), lower radiation dose, and most importantly, simultaneous multiple material identification. One potential way of material identification is via calculation of effective atomic number (Z_eff) and effective electron density (pe_eff) from PCCT image data. However, the current methods for calculating effective atomic number and effective electron density from PCCT image data are mostly based on semi-empirical models and accordingly are not sufficiently accurate. Here, we present a physics-based model to calculate the effective atomic number and effective electron density of various matters, including single element substances, molecular compounds, and multi-material mixtures as well. The model was validated over several materials under various combinations of energy bins. A PCCT system was simulated to generate the PCCT image data, and the proposed model was applied to the PCCT image data. Our model yielded a relative standard deviations for effective atomic numbers and effective electron densities at less than 1%. Our results further showed that five different materials can be simultaneously identified and well separated in a Z_eff − pe_eff map. The model could serve as a basis for simultaneous material identification from PCCT.

Citation Download Citation

Xu Dong, Olga V. Pen, Zhicheng Zhang, and Guohua Cao "An improved physics model for multi-material identification in photon counting CT", Proc. SPIE 10948, Medical Imaging 2019: Physics of Medical Imaging, 109484O (1 March 2019); https://doi.org/10.1117/12.2512525

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