title: New scanning technique using Adaptive Statistical Iterative Reconstruction (ASIR) significantly reduced the radiation dose of cardiac CT.
abstract: BACKGROUND
  The aims of our study were to evaluate the effect of application of Adaptive Statistical Iterative Reconstruction (ASIR) algorithm on the radiation dose of coronary computed tomography angiography (CCTA) and its effects on image quality of CCTA and to evaluate the effects of various patient and CT scanning factors on the radiation dose of CCTA.
  
  
  METHODS
  This was a retrospective study that included 347 consecutive patients who underwent CCTA at a tertiary university teaching hospital between 1 July 2009 and 20 September 2011. Analysis was performed comparing patient demographics, scan characteristics, radiation dose and image quality in two groups of patients in whom conventional Filtered Back Projection (FBP) or ASIR was used for image reconstruction.
  
  
  RESULTS
  There were 238 patients in the FBP group and 109 patients in the ASIR group. There was no difference between the groups in the use of prospective gating, scan length or tube voltage. In ASIR group, significantly lower tube current was used compared with FBP group, 550 mA (450-600) vs. 650 mA (500-711.25) (median (interquartile range)), respectively, P < 0.001. There was 27% effective radiation dose reduction in the ASIR group compared with FBP group, 4.29 mSv (2.84-6.02) vs. 5.84 mSv (3.88-8.39) (median (interquartile range)), respectively, P < 0.001. Although ASIR was associated with increased image noise compared with FBP (39.93 ± 10.22 vs. 37.63 ± 18.79 (mean ± standard deviation), respectively, P < 0.001), it did not affect the signal intensity, signal-to-noise ratio, contrast-to-noise ratio or the diagnostic quality of CCTA.
  
  
  CONCLUSIONS
  Application of ASIR reduces the radiation dose of CCTA without affecting the image quality.
authors.affiliation: Western Health, Footscray, Victoria, Australia. t_odgerel@hotmail.com
authors.forename: Odgerel
authors.initials: O
authors.lastname: Tumur
authors.forename: Kean
authors.initials: K
authors.lastname: Soon
authors.forename: Fraser
authors.initials: F
authors.lastname: Brown
authors.forename: Marcus
authors.initials: M
authors.lastname: Mykytowycz
mesh_terms: D001315:Australia / Q000453:epidemiology; D001822:Body Burden; D017023:Coronary Angiography / Q000706:statistics & numerical data*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000517:prevention & control; D011835:Radiation Protection / Q000379:methods / Q000706:statistics & numerical data*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011874:Radiometry / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*