Comparison of spectral performance of three dual-energy CT scanners equipped with a deep-learning image reconstruction algorithm and one photon counting CT scanner: A phantom study.

Journal: Diagnostic and interventional imaging
Published Date: Nov 29, 2025

Abstract

PURPOSE: The purpose of this study was to compare the spectral performance of three dual-energy CT (DECT) scanners and one photon-counting CT (PCCT) scanner on virtual monoenergetic images (VMIs) at low-energy levels and on iodine maps. MATERIALS AND METHODS: A spectral phantom was scanned using one PCCT scanner and three different DECT scanners that included a rapid kV-switching CT (R-KVSCT), an ultrafast kV-switching (U-KVSCT) and a dual-layer CT (DLCT) scanner. Acquisitions were obtained with each CT system using classical abdominal and pelvic examination parameters, as well as a volume CT dose index at 11 mGy. VMI at 40/50/60/70 keV and iodine maps were reconstructed for each scanner. Noise power spectrum (NPS) and task-based transfer function (TTF) were evaluated. Detectability indexes (d') were computed to model the detection task of two contrast-enhanced lesions. RESULTS: Noise magnitude decreased from 40 to 70 keV for all DECT scanners and this decrease was greater for R-KVSCT (-80.0 ± 0.1 [standard deviation (SD)] %) and less pronounced for DLCT (-14.4 ± 0.8 [SD] %) scanners. The average NPS spatial frequency (fav) values decreased from 40 to 70 keV (0.26 to 0.17 mm-1) for R-KVSCT, increased for DLCT (0.18 to 0.25 mm-1) but were similar for U-KVSCT (0.19 ± 0.002 [SD] mm-1) and PCCT (0.21 ± [SD] 0.008 mm-1) scanner. For R-KVSCT and PCCT scanners, TTF at 50 % (f50) values increased from 40 to 70 keV for both inserts. For U-KVSCT and DLCT scanners, similar f50 values were found according to energy level for both inserts. For both contrast-enhanced lesions, d' values decreased from 40 to 70 keV for PCCT, DLCT and U-KVSCT scanners. For R-KVSCT scanner, d' values peaked at 60 keV. At 40 and 50 keV, the greatest d' values were found with DLCT and PCCT scanners. CONCLUSION: At 40 or 50 keV, the best combined results (objective and subjective assessments) are obtained with DLCT and PCCT scanners.

Authors

  • Joël Greffier
    Department of Medical Imaging, CHU Nimes, Medical Imaging Group Nimes, Univ Montpellier, EA 2415, Bd Prof Robert Debré, 30029, Nîmes Cedex 9, France. [email protected].
  • Cécile Salvat
    Department of Medical Physics, hôpital Lariboisière, AP-HP Nord-université Paris Cité, Paris, France.
  • Maxime Pastor
    IMAGINE UR UM 103, Montpellier University, Department of Medical Imaging, Nîmes University Hospital, 30029 Nîmes, France.
  • Valérie Bousson
    Université de Paris, 85 boulevard Saint-Germain, Paris 75006, France; Radiology Department, Hopital Lariboisiére - AP-HP.Nord Université de Paris, 2 Rue Ambroise Paré, Paris 75010, France.
  • Salim Si-Mohamed
    Department of Radiology, Hospices Civils de Lyon, 69500 Lyon, France.
  • Jean-Paul Beregi
    DRIM France IA, 75013 Paris, France; Collège des Enseignants en Radiologie de France (CERF), 75013 Paris, France; Medical Imaging Group Nîmes, Nîmes University Hospital, 34000 Nîmes, France.
  • Lama Hadid-Beurrier
    Medical Physics Department, Lariboisière's Hospital, AP-HP.Nord-Université de Paris, Paris, France (L.H.-B., C.S.).
  • Djamel Dabli
    Department of Medical Imaging, CHU Nimes, Univ Montpellier, Medical Imaging Group Nimes, EA 2992, 30029 Nîmes, France.

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