title: Feasibility of radiation dose reduction using AIDR-3D in dynamic pulmonary CT perfusion.
abstract: OBJECTIVE
  To assess the feasibility of radiation dose reduction with adaptive iterative dose reduction (AIDR-6 3D) reconstruction in dynamic pulmonary CT perfusion.
  
  
  METHODS
  CTP examinations of 10 patients acquired at 100 kVp/50 mAs were reconstructed with filtered back projection (FBP) and AIDR-3D. Artificial noise was added to raw data (pre-reconstruction projection data) to simulate lower tube current scanning. Radiodensity (in Hounsfield units), noise, and perfusion values were compared.
  
  
  RESULTS
  There was no significant difference in noise between the full and simulated reduced tube current with AIDR-3D reconstruction (p = 1). There was significantly lower noise in lung tissue with AIDR-3D images when compared to reconstructions without AIDR-3D (p = 0.005) and no significant change in the radiodensity (p = 1; mean difference <6 HU). Mean perfusion values increased significantly at lower tube currents (25 and 12.5 mAs), compared to 50 mAs (p = 0.005). This effect was significantly greater in larger patients compared to thin patients.
  
  
  CONCLUSIONS
  AIDR-3D produced significantly lower noise images than FBP-based algorithms and maintained consistent noise levels in lung at 12.5 mAs, indicating this algorithm is suitable for reduced dose lung perfusion imaging. Iterative reconstruction allows significant radiation dose reduction of up to fourfold in smaller patients, and up to twofold in the medium/large size patients. The increase in perfusion values at 25% simulated tube currents is attributed to attenuation bias.
authors.affiliation: Clinical Research Imaging Centre, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK. Electronic address: saeed.mirsadraee@ed.ac.uk.
authors.forename: S
authors.initials: S
authors.lastname: Mirsadraee
authors.affiliation: Department of Radiology, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, UK.
authors.forename: N W
authors.initials: NW
authors.lastname: Weir
authors.affiliation: University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
authors.forename: S
authors.initials: S
authors.lastname: Connolly
authors.affiliation: Department of Radiology, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, UK.
authors.forename: J T
authors.initials: JT
authors.lastname: Murchison
authors.affiliation: Clinical Research Imaging Centre, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
authors.forename: J H
authors.initials: JH
authors.lastname: Reid
authors.affiliation: Department of Respiratory Medicine, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
authors.forename: N
authors.initials: N
authors.lastname: Hirani
authors.affiliation: Clinical Research Imaging Centre, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
authors.forename: M
authors.initials: M
authors.lastname: Connell
authors.affiliation: Clinical Research Imaging Centre, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
authors.forename: E J
authors.initials: EJ
authors.lastname: van Beek
mesh_terms: D000465:Algorithms; D004646:Emphysema / Q000000981:diagnostic imaging*; D005240:Feasibility Studies; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011658:Pulmonary Fibrosis / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*