Impact of photon counting detector technology on kV selection and diagnostic workflow in CT

Wei Zhou, Dilbar Abdurakhimova, Michael Bruesewitz, Ahmed Halaweish, Cynthia H. McCollough, Shuai Leng

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

5 Scopus citations


The purpose of this study is to determine the optimal iodine contrast-to-noise ratio (CNR) achievable for different patient sizes using virtual-monoenergetic-images (VMIs) and a universal acquisition protocol on photon-counting-detector CT (PCD-CT), and to compare results to those from single-energy (SE) and dualsource- dual-energy (DSDE) CT. Vials containing 3 concentrations of iodine were placed in torso-shaped water phantoms of 5 sizes and scanned on a 2nd generation DSDE scanner with both SE and DE modes. Tube current was automatically adjusted based on phantom size with CTDIvol ranging from 5.1 to 22.3 mGy. PCD-CT scans were performed at 140 kV, 25 and 75 keV thresholds, with CTDIvol matched to the SE scans. DE VMIs were created and CNR was calculated for SE images and DE VMIs. The optimal kV (SE) or keV (DE VMI) was chosen at the point of highest CNR with no noticeable artifacts. For 10 mgI/cc vials in the 35 cm phantom, the optimal CNR of VMIs on PCD (22.6@50keV) was comparable to that of the best DSDE protocol (23.9@50keV) and was higher than that of the best SE protocol (19.7@80kV). In general, the difference of optimal CNR between PCD and SE increased with phantom size, with PCD 50 keV VMIs having an equivalent CNR (0.6% difference) with that of SE at the 25 cm phantom and 57% higher CNR at the 45 cm phantom. PCD-CT demonstrated comparable iodine CNR of VMIs to that of DSDE across patient sizes. Whereas SE and DSDE CT exams require use of patient-size-specific acquisitions settings, our findings point to the ability of PCD-CT to simplify protocol selection, using a single VMI keV setting (50 keV), acquisition kV (140 kV), and energy thresholds (25 and 75 keV) for all patient sizes, while achieving optimal or near optimal iodine CNR values.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2018
Subtitle of host publicationPhysics of Medical Imaging
EditorsTaly Gilat Schmidt, Guang-Hong Chen, Joseph Y. Lo
ISBN (Electronic)9781510616356
StatePublished - 2018
EventMedical Imaging 2018: Physics of Medical Imaging - Houston, United States
Duration: Feb 12 2018Feb 15 2018

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherMedical Imaging 2018: Physics of Medical Imaging
Country/TerritoryUnited States


  • Computed tomography (CT)
  • dual energy
  • kV selection
  • photon counting detector (PCD)
  • virtual monoenergetic image (VMI)

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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