title: Radiation Dose Consideration in Kidney Stone CT Examinations: Integration of Iterative Reconstruction Algorithms With Routine Clinical Practice.
abstract: OBJECTIVE
  The objective of our study was to evaluate three commercially available iterative reconstruction (IR) algorithms-ASiR, iDOSE, and SAFIRE-and conventional filtered back projection (FBP) on image quality and radiation dose in kidney stone CT examinations.
  
  
  METHODS
  During the 6-month study period, 684 unenhanced kidney stone CT examinations of consecutive adults were performed on 17 CT scanners (GE Healthcare [vendor 1], n = 12 scanners; Philips Healthcare [vendor 2], n = 2; Siemens Health-care [vendor 3], n = 3); these examinations were retrieved using dose-monitoring software (eXposure). A total of 347 kidney stone CT examinations were reconstructed using FBP, and 337 examinations were processed using IR (ASiR, n = 248; iDOSE, n = 50; SAFIRE, n = 39). The standard-dose scanning parameters for FBP scanners included a tube potential of 120 kVp, a tube current of 75-450 mA for vendor 1 and a Quality Reference mAs of 160-180 for vendor 3, and a slice thickness of 2.5 or 5 mm. The dose-modified protocol for the IR scanners included a higher noise index (1.4 times higher than the standard-dose FBP protocol) for vendor 1, a lower reference tube current-exposure time product for vendor 2 (150 reference mAs), and a lower Quality Reference mAs for vendor 3 (120 Quality Reference mAs). Three radiologists independently reviewed 60 randomly sampled kidney stone CT examinations for image quality, noise, and artifacts. Objective noise and attenuation were also determined. Size-specific dose estimates (SSDEs) were compared using ANOVA.
  
  
  RESULTS
  Significantly higher subjective and objective measurements of image noise were found in FBP examinations compared with dose-modified IR examinations (p < 0.05). The radiation dose was substantially lower for the dose-modified IR examinations than the standard-dose FBP examinations (mean SSDE ± SD: 8.1 ± 3.8 vs 11.6 ± 3.6 mGy, respectively) (p < 0.0001), but the radiation dose was comparable among the three IR techniques (ASiR, 7.8 ± 3.1 mGy; iDOSE, 7.5 ± 1.9 mGy; SAFIRE, 7.6 ± 3.2 mGy) (p > 0.05).
  
  
  CONCLUSIONS
  The three IRs enable 20-33% radiation dose reduction in kidney stone CT examinations compared with the FBP technique without any image quality concerns. The radiation dose and image quality were comparable among these three IR algorithms.
authors.affiliation: 1 Department of Radiology, Division of Abdominal Imaging and Intervention, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St, White 270, Boston, MA 02114-2696.
authors.forename: Yasir
authors.initials: Y
authors.lastname: Andrabi
authors.forename: Oleg
authors.initials: O
authors.lastname: Pianykh
authors.forename: Mukta
authors.initials: M
authors.lastname: Agrawal
authors.forename: Avinash
authors.initials: A
authors.lastname: Kambadakone
authors.forename: Michael A
authors.initials: MA
authors.lastname: Blake
authors.forename: Dushyant V
authors.initials: DV
authors.lastname: Sahani
mesh_terms: D000465:Algorithms; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: CT; dose monitoring; iterative reconstruction; kidney stones; radiation dose