title: How Different Iterative and Filtered Back Projection Kernels Affect Computed Tomography Numbers and Low Contrast Detectability.
abstract: OBJECTIVE
  The aim of this study was to evaluate how different iterative and filtered back projection kernels affect the computed tomography (CT) numbers and low contrast detectability.
  
  
  METHODS
  Five different scans were performed at 6 different tube potentials on the same Catphan 600 phantom using approximately the same dose level and otherwise identical settings. The scans were reconstructed using all available filtered back projection body kernels and with iterative reconstruction techniques.
  
  
  RESULTS
  The CT numbers and the contrast-to-noise ratios were reported and how they are affected by the kernel choice and strength of iterative reconstruction.
  
  
  CONCLUSIONS
  Iterative reconstruction improved contrast-to-noise ratio in most cases, but in certain situations, it decreased it. Variations in CT numbers can be large between kernels with similar sharpness for certain densities.
authors.affiliation: From the *Faculty of Computer Science and Media Technology, Gjøvik University College, Gjøvik; †Department of Research and Development in Forensic Pathology, The Norwegian Institute of Public Health; ‡Department of Forensic Medicine, University of Oslo, Oslo; §Faculty of Health, Care and Nursing, Gjøvik University College, Gjøvik; ∥The Intervention Centre, Oslo University Hospital Rikshospitalet; and ¶Department of Physics, University of Oslo, Oslo, Norway.
authors.forename: David
authors.initials: D
authors.lastname: Völgyes
authors.forename: Marius
authors.initials: M
authors.lastname: Pedersen
authors.forename: Arne
authors.initials: A
authors.lastname: Stray-Pedersen
authors.forename: Dag
authors.initials: D
authors.lastname: Waaler
authors.forename: Anne Catrine Trægde
authors.initials: AC
authors.lastname: Martinsen
mesh_terms: D000465:Algorithms; D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*