University of Oulu

Mikael A. K. Juntunen, Antti O. Kotiaho, Miika T. Nieminen, Satu I. Inkinen, "Optimizing iterative reconstruction for quantification of calcium hydroxyapatite with photon counting flat-detector computed tomography: a cardiac phantom study," J. Med. Imag. 8(5) 052102 (10 March 2021)

Optimizing iterative reconstruction for quantification of calcium hydroxyapatite with photon counting flat-detector computed tomography : a cardiac phantom study

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Author: Juntunen, Mikael A. K.1,2; Kotiaho, Antti O.2; Nieminen, Miika T.1,2,3;
Organizations: 1University of Oulu, Research Unit of Medical Imaging, Physics, and Technology, Oulu, Finland
2Oulu University Hospital, Department of Diagnostic Radiology, Oulu, Finland
3Medical Research Center, University of Oulu, Oulu University Hospital, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.1 MB)
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Language: English
Published: SPIE, 2021
Publish Date: 2021-12-03


Purpose: Coronary artery calcium (CAC) scoring with computed tomography (CT) has been proposed as a screening tool for coronary artery disease, but concerns remain regarding the radiation dose of CT CAC scoring. Photon counting detectors and iterative reconstruction (IR) are promising approaches for patient dose reduction, yet the preservation of CAC scores with IR has been questioned. The purpose of this study was to investigate the applicability of IR for quantification of CAC using a photon counting flat-detector.

Approach: We imaged a cardiac rod phantom with calcium hydroxyapatite (CaHA) inserts with different noise levels using an experimental photon counting flat-detector CT setup to simulate the clinical CAC scoring protocol. We applied filtered back projection (FBP) and two IR algorithms with different regularization strengths. We compared the air kerma values, image quality parameters [noise magnitude, noise power spectrum, modulation transfer function (MTF), and contrast-to-noise ratio], and CaHA quantification accuracy between FBP and IR.

Results: IR regularization strength influenced CAC scores significantly (p  <  0.05). The CAC volumes and scores between FBP and IRs were the most similar when the IR regularization strength was chosen to match the MTF of the FBP reconstruction.

Conclusion: When the regularization strength is selected to produce comparable spatial resolution with FBP, IR can yield comparable CAC scores and volumes with FBP. Nonetheless, at the lowest radiation dose setting, FBP produced more accurate CAC volumes and scores compared to IR, and no improved CAC scoring accuracy at low dose was demonstrated with the utilized IR methods.

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Series: Journal of medical imaging
ISSN: 2329-4302
ISSN-E: 2329-4310
ISSN-L: 2329-4302
Volume: 8
Issue: 5
Article number: 052102
DOI: 10.1117/1.JMI.8.5.052102
Type of Publication: A1 Journal article – refereed
Field of Science: 217 Medical engineering
Funding: This research was financially supported by the Academy of Finland (Project No. 316899), Business Finland (Project No. 1392/31/2016), Jenny and Antti Wihuri Foundation, Otto A. Malm Foundation, Oulu University Hospital (No. VTR K33745), and Tauno Tönning Foundation. We thank Detection Technology Oyj. for allowing access to its x-ray lab.
Academy of Finland Grant Number: 316899
Detailed Information: 316899 (Academy of Finland Funding decision)
Copyright information: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. [DOI: 10.1117/1.JMI.8.5.052102].