title: Dual-energy CT quantitative imaging: a comparison study between twin-beam and dual-source CT scanners.
abstract: OBJECTIVE
  To assess image quality and to quantify the accuracy of relative electron densities (ρe) and effective atomic numbers (Zeff) for three dual-energy computed tomography (DECT) scanners: a novel single-source split-filter (i.e., twin-beam) and two dual-source scanners.
  
  
  METHODS
  Measurements were made with a second generation dual-source scanner at 80/140Sn kVp, a third-generation twin-beam single-source scanner at 120 kVp with gold (Au) and tin (Sn) filters, and a third-generation dual-source scanner at 90/150Sn kVp. Three phantoms with tissue inserts were scanned and used for calibration and validation of parameterized methods to extract ρeand Zeff, whereas iodine and calcium inserts were used to quantify Contrast-to-Noise-Ratio (CNR). Spatial resolution in tomographic images was also tested.
  
  
  RESULTS
  The third-generation scanners have an image resolution of 6.2, ~0.5 lp/cm higher than the second generation scanner. The twin-beam scanner has low imaging contrast for iodine materials due to its limited spectral separation. The parameterization methods resulted in calibrations with low fit residuals for the dual-source scanners, yielding values of ρeand Zeffclose to the reference values (errors within 1.2% for ρeand 6.2% for Zefffor a dose of 20 mGy, excluding lung substitute tissues). The twin-beam scanner presented overall higher errors (within 3.2% for ρeand 28% for Zeff, also excluding lung inserts) and also larger variations for uniform inserts.
  
  
  CONCLUSIONS
  Spatial resolution is similar for the three scanners. The twin-beam is able to derive ρeand Zeff, but with inferior accuracy compared to both dual-source scanners.
authors.affiliation: Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Isabel P
authors.initials: IP
authors.lastname: Almeida
authors.affiliation: Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Lotte E J R
authors.initials: LE
authors.lastname: Schyns
authors.affiliation: Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Michel C
authors.initials: MC
authors.lastname: Öllers
authors.affiliation: Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Wouter
authors.initials: W
authors.lastname: van Elmpt
authors.affiliation: Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748, Garching b. München, Germany.
authors.forename: Katia
authors.initials: K
authors.lastname: Parodi
authors.affiliation: Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748, Garching b. München, Germany.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Landry
authors.affiliation: Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Verhaegen
mesh_terms: D005240:Feasibility Studies; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D019279:Resin Cements; D059629:Signal-To-Noise Ratio; D015898:Tomography Scanners, X-Ray Computed
chemical_list: C433205:Calibra; D019279:Resin Cements
keywords: Dual-energy dual-source CT; Dual-energy twin-beam CT; effective atomic number; relative electron density