title: Computed tomography radiation dose reduction: effect of different iterative reconstruction algorithms on image quality.
abstract: OBJECTIVE
  We evaluated the effects of hybrid and model-based iterative reconstruction (IR) algorithms from different vendors at multiple radiation dose levels on image quality of chest phantom scans.
  
  
  METHODS
  A chest phantom was scanned on state-of-the-art computed tomography scanners from 4 vendors at 4 dose levels (4.1 mGy, 3.0 mGy, 1.9 mGy, and 0.8 mGy). All data were reconstructed with filtered back projection (FBP) and reduced-dose data also with IR (iDose4, Adaptive Iterative Dose Reduction 3D, Adaptive Statistical Iterative Reconstruction, Sinogram-Affirmed Iterative Reconstruction, prototype Iterative Model Reconstruction, and Veo). Computed tomography numbers and noise were measured in the spine and lungs. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated and differences were analyzed with the Friedman test.
  
  
  RESULTS
  For all vendors, radiation dose reduction with FBP resulted in significantly increased noise levels (≤148%) as well as decreased SNR (≤57%) and CNR (≤58%) (P < 0.001). Conversely, IR resulted in decreased noise levels (≤48%) as well as increased SNR (≤94%) and CNR (≤94%). The SNRs and CNRs of the model-based algorithms at 80% reduced dose were similar to reference-dose FBP.
  
  
  CONCLUSIONS
  Hybrid IR algorithms have the potential to reduce radiation dose with 27% to 54% and model-based IR algorithms with up to 80%.
authors.affiliation: From the Departments of *Radiology, and †Anatomy, University Medical Center Utrecht, Utrecht; ‡Maastricht University Medical Center, Maastricht; §Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands; and ∥Department of Radiology, UZ Brussel, Brussels, Belgium.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Willemink
authors.forename: Richard A P
authors.initials: RA
authors.lastname: Takx
authors.forename: Pim A
authors.initials: PA
authors.lastname: de Jong
authors.forename: Ricardo P J
authors.initials: RP
authors.lastname: Budde
authors.forename: Ronald L A W
authors.initials: RL
authors.lastname: Bleys
authors.forename: Marco
authors.initials: M
authors.lastname: Das
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Wildberger
authors.forename: Mathias
authors.initials: M
authors.lastname: Prokop
authors.forename: Nico
authors.initials: N
authors.lastname: Buls
authors.forename: Johan
authors.initials: J
authors.lastname: de Mey
authors.forename: Tim
authors.initials: T
authors.lastname: Leiner
authors.forename: Arnold M R
authors.initials: AM
authors.lastname: Schilham
mesh_terms: D000465:Algorithms; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000592:standards*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*