Research on accuracy of material identification based on photon counting spectral CT

Article type: Research Article

Authors: Zhang, Xiaomei^{a; b; 1} | Wang, Zhe^{a; c; *} | Yun, Xiangyu^{a; b} | Li, Mohan^{a; c} | Hu, Jinming^{a; b} | Wang, Chengmin^{a; b} | Wei, Cunfeng^{a; b; c; *}

Affiliations: [a] Beijing Engineering Research Center of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China | [b] School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China | [c] Jinan Laboratory of Applied Nuclear Science, Jinan, China

Correspondence: [*] Corresponding author: Cunfeng Wei and Zhe Wang, Beijing Engineering Research Center of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China. E-mails: [email protected] (CW), [email protected] (ZW).

Note: [1] ORCID ID: Xiaomei Zhang https://orcid.org/0009-0000-3332-339X

Abstract: BACKGROUND:Photon counting spectral CT is a significant direction in the development of CT technology and material identification is an important application of spectral CT. However, spectrum estimation in photon counting spectral CT is highly complex and may affect quantification accuracy of material identification. OBJECTIVE:To address the problem of energy spectrum estimation in photon-counting spectral CT, this study investigates empirical material decomposition algorithms to achieve accurate quantitative decomposition of the effective atomic number. METHODS:The spectrum is first calibrated using the empirical dual-energy calibration (EDEC) method and the effective atomic number is then quantitatively estimated based on the EDEC method. The accuracy of estimating the effective atomic number of materials under different calibration conditions is investigated by designing different calibration phantoms, and accurate quantitation is achieved using suitable calibration settings. Last, the validity of this method is verified through simulations and experimental studies. RESULTS:The results demonstrate that the error in estimating the effective atomic number is reduced to within 4% for low and medium Z materials, thereby enabling accurate material identification. CONCLUSION:The empirical dual-energy correction method can solve the problem of energy spectrum estimation in photon counting spectral CT. Accurate effective atomic number estimation can be achieved with suitable calibration.

Keywords: Photon counting detectors (PCDs), material decomposition, spectral CT, effective atomic number, polynomial fitting, calibration phantoms

DOI: 10.3233/XST-230054

Journal: Journal of X-Ray Science and Technology, vol. 31, no. 4, pp. 811-824, 2023