An in silico evaluation of signal and separability properties of k-edge materials in spectral CT

Jayasai R. Rajagopal; Faraz Farhadi; Pooyan Sahbaee; Elizabeth C. Jones; Ehsan Samei; William F. Pritchard

doi:10.1038/s41598-025-21693-0

An in silico evaluation of signal and separability properties of k-edge materials in spectral CT

Jayasai R. Rajagopal
, Faraz Farhadi
, Pooyan Sahbaee
, Elizabeth C. Jones
, Ehsan Samei
, William F. Pritchard

Research output: Contribution to journal › Article › peer-review

Abstract

Spectral CT can acquire signal at multiple x-ray energy levels. This enables material quantification by exploiting differences in x-ray attenuation across energy levels, particularly for k-edge materials. This simulation study quantified the signal and separability of current and potential clinical contrast agents across a range of materials and energies. A validated CT simulation platform was used to simulate a clinical photon-counting CT scanner with two energy thresholds. A cylindrical phantom containing common biological materials, clinical contrast agents, candidate contrast agents and nanoparticles, and investigational materials was imaged with varying upper energy thresholds (50–90 keV). At each energy level, images were assessed for noise, each material was assessed for contrast, and each material pair was evaluated for separability. Material contrasts reached peak value at the closest threshold higher than their respective k-edge. The energy threshold that produced the highest separability for each pair was characterized. Selection of energy threshold was dependent on the materials of interest. Threshold values at or just above a material’s k-edge maximized material signal while separability was maximized by the threshold that best separated k-edge signals.

Original language	English
Article number	5365
Journal	Scientific Reports
Volume	16
Issue number	1
DOIs	https://doi.org/10.1038/s41598-025-21693-0
State	Published - Dec 2026
Externally published	Yes

Funding

This study was supported in part by the National Institutes of Health (NIH) Clinical Center Radiology and Imaging Sciences (RADIS), the NIH Graduate Partnership Program, the NIH Intramural Research Program and NIH grant P41EB028744. Author PS is an employee of Siemens Healthineers. Author ES lists relationships with the following entities unrelated to the present publication: GE, Siemens, Imalogix, Metis Health Analytics, Cambridge University Press, and Wiley and Sons. The other authors list no competing interests.The contributions of the NIH authors were made as part of their official duties as NIH federal employees, are in compliance with agency policy requirements, and are considered Works of the United States Government. However, the findings and conclusions presented in this paper are those of the author(s) and do not necessarily reflect the views of the NIH or the U.S. Department of Health and Human Services.

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title = "An in silico evaluation of signal and separability properties of k-edge materials in spectral CT",

abstract = "Spectral CT can acquire signal at multiple x-ray energy levels. This enables material quantification by exploiting differences in x-ray attenuation across energy levels, particularly for k-edge materials. This simulation study quantified the signal and separability of current and potential clinical contrast agents across a range of materials and energies. A validated CT simulation platform was used to simulate a clinical photon-counting CT scanner with two energy thresholds. A cylindrical phantom containing common biological materials, clinical contrast agents, candidate contrast agents and nanoparticles, and investigational materials was imaged with varying upper energy thresholds (50–90 keV). At each energy level, images were assessed for noise, each material was assessed for contrast, and each material pair was evaluated for separability. Material contrasts reached peak value at the closest threshold higher than their respective k-edge. The energy threshold that produced the highest separability for each pair was characterized. Selection of energy threshold was dependent on the materials of interest. Threshold values at or just above a material{\textquoteright}s k-edge maximized material signal while separability was maximized by the threshold that best separated k-edge signals.",

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AU - Farhadi, Faraz

AU - Sahbaee, Pooyan

AU - Jones, Elizabeth C.

AU - Samei, Ehsan

AU - Pritchard, William F.

PY - 2026/12

Y1 - 2026/12

N2 - Spectral CT can acquire signal at multiple x-ray energy levels. This enables material quantification by exploiting differences in x-ray attenuation across energy levels, particularly for k-edge materials. This simulation study quantified the signal and separability of current and potential clinical contrast agents across a range of materials and energies. A validated CT simulation platform was used to simulate a clinical photon-counting CT scanner with two energy thresholds. A cylindrical phantom containing common biological materials, clinical contrast agents, candidate contrast agents and nanoparticles, and investigational materials was imaged with varying upper energy thresholds (50–90 keV). At each energy level, images were assessed for noise, each material was assessed for contrast, and each material pair was evaluated for separability. Material contrasts reached peak value at the closest threshold higher than their respective k-edge. The energy threshold that produced the highest separability for each pair was characterized. Selection of energy threshold was dependent on the materials of interest. Threshold values at or just above a material’s k-edge maximized material signal while separability was maximized by the threshold that best separated k-edge signals.

AB - Spectral CT can acquire signal at multiple x-ray energy levels. This enables material quantification by exploiting differences in x-ray attenuation across energy levels, particularly for k-edge materials. This simulation study quantified the signal and separability of current and potential clinical contrast agents across a range of materials and energies. A validated CT simulation platform was used to simulate a clinical photon-counting CT scanner with two energy thresholds. A cylindrical phantom containing common biological materials, clinical contrast agents, candidate contrast agents and nanoparticles, and investigational materials was imaged with varying upper energy thresholds (50–90 keV). At each energy level, images were assessed for noise, each material was assessed for contrast, and each material pair was evaluated for separability. Material contrasts reached peak value at the closest threshold higher than their respective k-edge. The energy threshold that produced the highest separability for each pair was characterized. Selection of energy threshold was dependent on the materials of interest. Threshold values at or just above a material’s k-edge maximized material signal while separability was maximized by the threshold that best separated k-edge signals.

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An in silico evaluation of signal and separability properties of k-edge materials in spectral CT

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