University of Oulu

Satu I Inkinen et al 2022 Biomed. Phys. Eng. Express 8 015029,

Virtual monochromatic imaging reduces beam hardening artefacts in cardiac interior photon counting computed tomography : a phantom study with cadaveric specimens

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Author: Inkinen, Satu I.1; Juntunen, Mikael A. K.1,2; Ketola, Juuso1,3;
Organizations: 1Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
2Oulu University Hospital, Department of Diagnostic Radiology, Oulu, Finland
3The South Savo Social and Health Care Authority, Mikkeli Central Hospital, Mikkeli, Finland
4Cancer and Translational Medicine Research Unit, Medical Research Center, University of Oulu and Oulu University Hospital, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.6 MB)
Persistent link:
Language: English
Published: IOP Publishing, 2021
Publish Date: 2023-06-09


In interior cardiac computed tomography (CT) imaging, the x-ray beam is collimated to a limited field-of-view covering the heart volume, which decreases the radiation exposure to surrounding tissues. Spectral CT enables the creation of virtual monochromatic images (VMIs) through a computational material decomposition process. This study investigates the utility of VMIs for beam hardening (BH) reduction in interior cardiac CT, and further, the suitability of VMIs for coronary artery calcium (CAC) scoring and volume assessment is studied using spectral photon counting detector CT (PCD-CT). Ex vivo coronary artery samples (N = 18) were inserted in an epoxy rod phantom. The rod was scanned in the conventional CT geometry, and subsequently, the rod was positioned in a torso phantom and re-measured in the interior PCD-CT geometry. The total energy (TE) 10–100 keV reconstructions from PCD-CT were used as a reference. The low energy 10–60 keV and high energy 60–100 keV data were used to perform projection domain material decomposition to polymethyl methacrylate and calcium hydroxylapatite basis. The truncated basis-material sinograms were extended using the adaptive detruncation method. VMIs from 30–180 keV range were computed from the detruncated virtual monochromatic sinograms using filtered back projection. Detrending was applied as a post-processing method prior to CAC scoring. The results showed that BH artefacts from the exterior structures can be suppressed with high (≥100 keV) VMIs. With appropriate selection of the monoenergy (46 keV), the underestimation trend of CAC scores and volumes shown in Bland-Altman (BA) plots for TE interior PCD-CT was mitigated, as the BA slope values were −0.02 for the 46 keV VMI compared to −0.21 the conventional TE image. To conclude, spectral PCD-CT imaging using VMIs could be applied to reduce BH artefacts interior CT geometry, and further, optimal selection of VMI may improve the accuracy of CAC scoring assessment in interior PCD-CT.

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Series: Biomedical physics & engineering express
ISSN: 2057-1976
ISSN-E: 2057-1976
ISSN-L: 2057-1976
Volume: 8
Article number: 015029
DOI: 10.1088/2057-1976/ac4397
Type of Publication: A1 Journal article – refereed
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
Funding: The authors acknowledge financial support from Business Finland (project no. 1392/31/2016), Academy of Finland (project no. 316899).
Academy of Finland Grant Number: 316899
Detailed Information: 316899 (Academy of Finland Funding decision)
Copyright information: © 2021 The Author(s). Published by IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.