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Influence of Radiation Dose, Photon Energy, and Reconstruction Kernel on rho/z Analysis in Spectral Computer Tomography: A Phantom Study


Chatzaraki, Vasiliki; Bolsi, Alessandra; Kubik-Huch, Rahel A; Schmidt, Bernhard; Lomax, Antony John; Weber, Damien C; Thali, Michael; Niemann, Tilo (2022). Influence of Radiation Dose, Photon Energy, and Reconstruction Kernel on rho/z Analysis in Spectral Computer Tomography: A Phantom Study. In Vivo, 36(2):678-686.

Abstract

Background/aim: The effective atomic number (Zeff) and electron density relative to water (ρe or Rho) of elements can be derived in dual-energy computed tomography (DECT). The aim of this phantom study was to investigate the effect of different photon energies, radiation doses, and reconstruction kernels on Zeff and Rho measured in DECT.
Materials and methods: An anthropomorphic head phantom including five probes of known composition was scanned under three tube-voltage combinations in DECT: Sn140/100 kV, 140/80 kV and Sn140/80 kV with incremented radiation doses. Raw data were reconstructed with four reconstruction kernels (I30, I40, I50, and I70). Rho and Zeff were measured for each probe for all possible combinations of scan and reconstruction parameters.
Results: DECT-based Rho and Zeff closely approached the reference values with a mean and maximum error of 1.7% and 6.8%, respectively. Rho was lower for 140/80 kV compared with Sn140/100 kV and Sn140/80 kV with differences being 0.009. Zeff differed among all tube voltages with the most prominent difference being 0.28 between 140/80 kV and Sn140/100 kV. Zeff was lower in I70 compared with those of I30 and I40 with a difference of 0.07. Varying radiation dose yielded a variation of 0.0002 in Rho and 0.03 in Z, both considered negligible in practice.
Conclusion: DECT comprises a feasible method for the extraction of material-specific information. Slight variations should be taken into account when different radiation doses, photon energies, and kernels are applied; however, they are considered small and in practice not crucial for an effective tissue differentiation.

Keywords: Tomography; X-ray computed; image reconstruction; radiation dosage.

Abstract

Background/aim: The effective atomic number (Zeff) and electron density relative to water (ρe or Rho) of elements can be derived in dual-energy computed tomography (DECT). The aim of this phantom study was to investigate the effect of different photon energies, radiation doses, and reconstruction kernels on Zeff and Rho measured in DECT.
Materials and methods: An anthropomorphic head phantom including five probes of known composition was scanned under three tube-voltage combinations in DECT: Sn140/100 kV, 140/80 kV and Sn140/80 kV with incremented radiation doses. Raw data were reconstructed with four reconstruction kernels (I30, I40, I50, and I70). Rho and Zeff were measured for each probe for all possible combinations of scan and reconstruction parameters.
Results: DECT-based Rho and Zeff closely approached the reference values with a mean and maximum error of 1.7% and 6.8%, respectively. Rho was lower for 140/80 kV compared with Sn140/100 kV and Sn140/80 kV with differences being 0.009. Zeff differed among all tube voltages with the most prominent difference being 0.28 between 140/80 kV and Sn140/100 kV. Zeff was lower in I70 compared with those of I30 and I40 with a difference of 0.07. Varying radiation dose yielded a variation of 0.0002 in Rho and 0.03 in Z, both considered negligible in practice.
Conclusion: DECT comprises a feasible method for the extraction of material-specific information. Slight variations should be taken into account when different radiation doses, photon energies, and kernels are applied; however, they are considered small and in practice not crucial for an effective tissue differentiation.

Keywords: Tomography; X-ray computed; image reconstruction; radiation dosage.

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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Legal Medicine
Dewey Decimal Classification:340 Law
610 Medicine & health
Scopus Subject Areas:Life Sciences > General Biochemistry, Genetics and Molecular Biology
Life Sciences > Pharmacology
Uncontrolled Keywords:Pharmacology, General Biochemistry, Genetics and Molecular Biology, Cancer Research
Language:English
Date:1 January 2022
Deposited On:27 May 2022 13:32
Last Modified:28 May 2024 01:37
Publisher:International Institute of Anticancer Research
ISSN:0258-851X
OA Status:Gold
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.21873/invivo.12753
PubMed ID:35241522
Other Identification Number:EMBASE: L2017647953
  • Content: Published Version
  • Language: English
  • Licence: Creative Commons: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)