Human imaging with photon counting-based computed tomography at clinical dose levels: Contrast-to-noise ratio and cadaver studies

Ralf Gutjahr, Ahmed F. Halaweish, Zhicong Yu, Shuai Leng, Lifeng Yu, Zhoubo Li, Steven M. Jorgensen, Erik L. Ritman, Steffen Kappler, Cynthia H. McCollough

Research output: Contribution to journalArticlepeer-review

108 Scopus citations


Objectives: The purpose of this work was to measure and compare the iodine contrast-to-noise ratio (CNR) between a commercial energy-integrating detector (EID) computed tomography (CT) system and a photon-counting detector (PCD) CT scanner capable of human imaging at clinical dose rates, as well as to determine clinical feasibility using human cadavers. Materials and Methods: A research dual-source PCD-CT scanner was used, where the "A" tube/detector subsystem used an EID and the "B" tube/detector subsystem used a PCD. Iodine CNR was measured in 4 anthropomorphic phantoms, simulating 4 patient sizes, at 4 tube potential settings. After biospecimen committee approval, PCD scans were performed on a fresh-frozen human head and a whole-body cadaver using clinical dose rates. Scans were repeated using the EID and identical parameters, and qualitative side-by-side comparisons were performed. Results: For the same photon fluence, phantom measurements demonstrated a mean increase in CNR of 11%, 23%, 31%, 38% for the PCD system, relative to the EID system, at 80, 100, 120, and 140 kV, respectively. Photon-counting detector CT additionally provided energy-selective imaging, where low- and high-energy images reflected the energy dependence of the iodine signal. Photon-counting detector images of cadaveric anatomy demonstrated decreased beam hardening and calcium blooming in the high-energy bin images and increased contrast in the low-energy bins images relative to the EID images. Threshold-based PCD images were qualitatively deemed equivalent in other aspects. Conclusions: The evaluated research PCD-CT system was capable of clinical levels of image quality at clinical dose rates. It further provided improved CNR relative to state-of-the-art EID-CT. The energy-selective bin images provide further opportunity for dual-energy and multienergy analyses.

Original languageEnglish (US)
Pages (from-to)421-429
Number of pages9
JournalInvestigative radiology
Issue number7
StatePublished - Jul 1 2016


  • Computed tomography
  • Multienergy CT
  • Photon-counting CT
  • Photon-counting detectors
  • Spectral CT

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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