title: Adaptive iterative dose reduction 3D versus filtered back projection in CT: evaluation of image quality.
abstract: OBJECTIVE
  The purpose of this study was to evaluate image quality with filtered back projection (FBP) and adaptive iterative dose reduction 3D (AIDR 3D).
  
  
  METHODS
  Phantom acquisitions were performed at six dose levels to assess spatial resolution, noise, and low-contrast detectability (LCD). Spatial resolution was assessed with the modulation transfer function at high and low contrast levels. Noise power spectrum and SD of attenuation were assessed. LCD was calculated with a mathematic model observer applied to phantom CT images. The subjective image quality of clinical CT scans was assessed by five radiologists.
  
  
  RESULTS
  Compared with FBP, AIDR 3D resulted in substantial noise reduction at all frequencies with a similar shape of the noise power spectrum. Spatial resolution was similar for AIDR 3D and FBP. LCD improved with AIDR 3D, which was associated with a potential average dose reduction of 36% (range, 9-86%). The observer study showed that overall image quality improved and artifacts decreased with AIDR 3D.
  
  
  CONCLUSIONS
  AIDR 3D performs better than FBP with regard to noise and LCD, resulting in better image quality, and performs similarly with respect to spatial resolution. The evaluation of image quality of clinical CT scans was consistent with the objective assessment of image quality with a phantom. The amount of dose reduction should be investigated for each clinical indication in studies with larger numbers of patients.
authors.affiliation: 1 Department of Radiology, Leiden University Medical Center, C2-S, PO Box 9600, 2300RC Leiden, The Netherlands.
authors.forename: Raoul M S
authors.initials: RM
authors.lastname: Joemai
authors.forename: Wouter J H
authors.initials: WJ
authors.lastname: Veldkamp
authors.forename: Lucia J M
authors.initials: LJ
authors.lastname: Kroft
authors.forename: Irene
authors.initials: I
authors.lastname: Hernandez-Giron
authors.forename: Jacob
authors.initials: J
authors.lastname: Geleijns
mesh_terms: D000465:Algorithms; D006801:Humans; D021621:Imaging, Three-Dimensional; D019047:Phantoms, Imaging; D011786:Quality Control; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*