title: Tube Current Modulation Between Single- and Dual-Energy CT With a Second-Generation Dual-Source Scanner: Radiation Dose and Image Quality.
abstract: OBJECTIVE
  The purpose of this study was to compare the effects of tube current modulation between single- and dual-energy CT with a second-generation dual-source scanner.
  
  
  METHODS
  Custom-made elliptic polymethylmethacrylate phantoms for slim and large patients were used. Absorbed radiation dose at the central point of the phantoms was measured with a solid-state detector while the phantoms were scanned in single-energy (120 kV) and dual-energy (100/Sn140, 80/Sn140, and 140/80 kV) modes with a second-generation dual-source CT scanner. Tube current modulation was activated in both modes, and quality reference tube current-time settings of 150, 300, 450, and 600 mAs were selected. Scanning was performed three times under the same conditions, and image noise was evaluated by measuring the SD of CT numbers in four separate regions of three adjacent images of the phantoms.
  
  
  RESULTS
  Absorbed dose increased and image noise decreased with an increase in quality reference tube current-time setting when the slim phantom was scanned. For the large phantom, the radiation dose and noise level reached a plateau above quality reference tube current-time settings of 300 mAs for 100/Sn140 kV and 450 mAs for 120 kV. The radiation dose was small and the noise level was large with 80/Sn140 kV compared with that obtained with 120 and 100/Sn140 kV at all quality reference tube current-time settings.
  
  
  CONCLUSIONS
  When a large phantom is scanned with 100/Sn140 kV, exposure demand for tube current modulation exceeds system limits at a lower quality reference tube current-time setting than for scanning 120 kV.
authors.affiliation: 1 Department of Quantum Medical Technology, Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Matsubara
authors.affiliation: 2 Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan.
authors.forename: Tadanori
authors.initials: T
authors.lastname: Takata
authors.affiliation: 3 Faculty of Radiological Technology, School of Health Sciences, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Masanao
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: 1 Department of Quantum Medical Technology, Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: 1 Department of Quantum Medical Technology, Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan.
authors.forename: Kichiro
authors.initials: K
authors.lastname: Koshida
authors.affiliation: 4 Department of Radiology, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Gabata
mesh_terms: D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*
keywords: dosimetry; dual-energy CT; image noise; radiation dose; tube current modulation