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Proceedings Paper

Determination of optimal image type and lowest detectable concentration for iodine detection on a photon counting detector-based multi-energy CT system
Author(s): Wei Zhou; Rachel Schornak; Gregory Michalak; Jayse Weaver; Dilbar Abdurakhimova; Andrea Ferrero; Kenneth A. Fetterly; Cynthia H. McCollough; Shuai Leng
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Paper Abstract

Photon counting detector (PCD) based multi-energy CT is able to generate different types of images such as virtual monoenergetic images (VMIs) and material specific images (e.g., iodine maps) in addition to the conventional single energy images. The purpose of this study is to determine the image type that has optimal iodine detection and to determine the lowest detectable iodine concentration using a PCD-CT system. A 35 cm body phantom with iodine inserts of 4 concentrations and 2 sizes was scanned on a research PCD-CT system. For each iodine concentration, 80 repeated scans were performed and images were reconstructed for each energy threshold. In addition, VMIs at different keVs and iodine maps were also generated. CNR was measured for each type of images. A channelized Hotelling observer was used to assess iodine detectability after being validated with human observer studies, with area under the ROC curve (AUC) as a figure of merit. The agreement between model and human observer performance indicated that model observer could serve as an effective approach to determine optimal image type for the clinical practice and to determine the lowest detectable iodine concentration. Results demonstrated that for all size and concentration combinations, VMI at 70 keV had similar performance as that of threshold low images, both of which outperformed the iodine map images. At the AUC value of 0.8, iodine concentration as low as 0.2 mgI/cc could be detected for an 8 mm object and 0.5 mgI/cc for a 4 mm object with a 5 mm slice thickness.

Paper Details

Date Published: 9 March 2018
PDF: 7 pages
Proc. SPIE 10573, Medical Imaging 2018: Physics of Medical Imaging, 105734U (9 March 2018); doi: 10.1117/12.2294949
Show Author Affiliations
Wei Zhou, Mayo Clinic (United States)
Rachel Schornak, Mayo Clinic (United States)
Gregory Michalak, Mayo Clinic (United States)
Jayse Weaver, Mayo Clinic (United States)
Dilbar Abdurakhimova, Mayo Clinic (United States)
Andrea Ferrero, Mayo Clinic (United States)
Kenneth A. Fetterly, Mayo Clinic (United States)
Cynthia H. McCollough, Mayo Clinic (United States)
Shuai Leng, Mayo Clinic (United States)

Published in SPIE Proceedings Vol. 10573:
Medical Imaging 2018: Physics of Medical Imaging
Joseph Y. Lo; Taly Gilat Schmidt; Guang-Hong Chen, Editor(s)

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