title: Radiation dose efficiency of dual-energy CT benchmarked against single-source, kilovoltage-optimized scans.
abstract: OBJECTIVE
  This study evaluated the radiation dose and image quality implications of dual-energy CT (DECT) use, compared with kilovoltage-optimized single-source/single-energy CT (SECT) on a dual-source Siemens Somatom(®) Definition Flash CT scanner (Siemens Healthcare, Forcheim, Germany).
  
  
  METHODS
  With equalized radiation dose (volumetric CT dose index), image noise (standard deviation of CT number) and signal-difference-to-noise ratio (SDNR) were measured and compared across three techniques: 100, 120 and 100/140 kVp (dual energy). Noise in a 30-cm-diameter water phantom and SDNR within unenhanced soft-tissue regions of a small adult (50 kg/165 cm) anthropomorphic phantom were utilized for the assessment.
  
  
  RESULTS
  Water phantom image noise decreased with DECT compared with the lower noise SECT setting of 120 kVp (p = 0.046). A decrease in SDNR within the anthropomorphic phantom was demonstrated at 120 kVp compared with the SECT kilovoltage-optimized setting of 100 kVp (p = 0.001). A further decrease in SDNR was observed for the DECT technique when compared with 120 kVp (p = 0.01).
  
  
  CONCLUSIONS
  On the Siemens Somatom Definition Flash system (Siemens Healthcare), and for equalized radiation dose conditions, image quality expressed as SDNR of unenhanced soft tissue may be compromised for DECT when compared with kilovoltage-optimized SECT, particularly for smaller patients.
  
  
  CONCLUSIONS
  DECT on a dual-source CT scanner may require a radiation dose increase to maintain unenhanced soft-tissue contrast detectability, particularly for smaller patients.
authors.affiliation: 1 Biomedical Technology Services, Health Support Queensland, Queensland, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Schick
authors.affiliation: 2 Division of Diagnostic Radiology, Princess Alexandra Hospital, Brisbane, Australia.
authors.forename: Jit
authors.initials: J
authors.lastname: Pratap
mesh_terms: D000328:Adult; D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*