Image quality characteristics for virtual monoenergetic images using dual-layer spectral detector CT: Comparison with conventional tube-voltage images |
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| Affiliation: | 1. Graduate School of Health Sciences, Kumamoto University, Kumamoto, Japan;2. Department of Radiology, Kumamoto University Hospital, Kumamoto, Japan;3. Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan;4. The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, USA;5. Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan;1. Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan;2. Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan;3. Department of Cardiovascular Medicine, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan;1. Department of Medical Imaging, British Columbia Children''s Hospital, Vancouver, Canada;2. Department of Medical Imaging, St Paul’s Hospital, Vancouver, Canada;3. Faculty of Health Sciences, The University of Sydney, Discipline of Medical Radiation Sciences, Cumberland Campus, Lidcombe, Australia;4. Department of Medical Imaging, Princess Alexandra Hospital, Brisbane, Australia;1. Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Switzerland;2. Division of Radiology and Nuclear Medicine, Kantonsspital St Gallen, Switzerland;1. Department of Medical Imaging, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210002, China;2. Department of Nuclear Medicine, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210002, China;3. Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29401, USA;4. Department of Interventional Radiology, Changzhou First People’s Hospital, Changzhou, Jiangsu 213003, China;1. Eberhard Karls University, Department of Radiology, Diagnostic and Interventional Radiology, Hoppe-Seyler-Str. 3, D-72076 Tübingen, Germany |
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| Abstract: | PurposeTo investigate the image quality characteristics for virtual monoenergetic images compared with conventional tube-voltage image with dual-layer spectral CT (DLCT).MethodsHelical scans were performed using a first-generation DLCT scanner, two different sizes of acrylic cylindrical phantoms, and a Catphan phantom. Three different iodine concentrations were inserted into the phantom center. The single-tube voltage for obtaining virtual monoenergetic images was set to 120 or 140 kVp. Conventional 120- and 140-kVp images and virtual monoenergetic images (40–200-keV images) were reconstructed from slice thicknesses of 1.0 mm. The CT number and image noise were measured for each iodine concentration and water on the 120-kVp images and virtual monoenergetic images. The noise power spectrum (NPS) was also calculated.ResultsThe iodine CT numbers for the iodinated enhancing materials were similar regardless of phantom size and acquisition method. Compared with the iodine CT numbers of the conventional 120-kVp images, those for the monoenergetic 40-, 50-, and 60-keV images increased by approximately 3.0-, 1.9-, and 1.3-fold, respectively. The image noise values for each virtual monoenergetic image were similar (for example, 24.6 HU at 40 keV and 23.3 HU at 200 keV obtained at 120 kVp and 30-cm phantom size). The NPS curves of the 70-keV and 120-kVp images for a 1.0-mm slice thickness over the entire frequency range were similar.ConclusionVirtual monoenergetic images represent stable image noise over the entire energy spectrum and improved the contrast-to-noise ratio than conventional tube voltage using the dual-layer spectral detector CT. |
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| Keywords: | Dual-layer spectral detector CT Virtual monoenergetic image Image quality Iodine Different object sizes |
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