Determination of optimal image type and lowest detectable concentration for iodine detection on a photon counting detector-based multi-energy CT system

Wei Zhou, Rachel Schornak, Gregory Michalak, Jayse Weaver, Dilbar Abdurakhimova, Andrea Ferrero, Kenneth A. Fetterly, Cynthia H McCollough, Shuai Leng

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

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.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2018
Subtitle of host publicationPhysics of Medical Imaging
PublisherSPIE
Volume10573
ISBN (Electronic)9781510616356
DOIs
StatePublished - Jan 1 2018
EventMedical Imaging 2018: Physics of Medical Imaging - Houston, United States
Duration: Feb 12 2018Feb 15 2018

Other

OtherMedical Imaging 2018: Physics of Medical Imaging
CountryUnited States
CityHouston
Period2/12/182/15/18

Keywords

  • computed tomography
  • iodine quantification
  • model observer
  • multi-energy
  • Photon-counting detectors

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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  • Cite this

    Zhou, W., Schornak, R., Michalak, G., Weaver, J., Abdurakhimova, D., Ferrero, A., Fetterly, K. A., McCollough, C. H., & Leng, S. (2018). Determination of optimal image type and lowest detectable concentration for iodine detection on a photon counting detector-based multi-energy CT system. In Medical Imaging 2018: Physics of Medical Imaging (Vol. 10573). [105734U] SPIE. https://doi.org/10.1117/12.2294949