title: AdaptiveIterative Dose Reduction in coronary CT angiography using 320-row CT: assessment of radiation dose reduction and image quality.
abstract: BACKGROUND
  Several methods have been developed to reduce the radiation dose in coronary computed tomography angiography (CTA).
  
  
  OBJECTIVE
  The objective of our study was to evaluate the effects of Adaptive Iterative Dose Reduction (AIDR) on objective and subjective image quality as well as the radiation dose, compared with conventional filtered back projection (FBP), in coronary CTA.
  
  
  METHODS
  We retrospectively reviewed 100 consecutive patients who underwent coronary CTA. In the first 50 patients, a higher tube current was used, and images were reconstructed with FBP. In the last 50 patients, a lower tube current was used, and images were reconstructed with AIDR. Subjective and objective image quality (noise, signal-to-noise ratio, contrast-to-noise ratio) were assessed.
  
  
  RESULTS
  The median radiation dose of the AIDR group was 22% lower than that of the FBP group (4.2 vs 5.4 mSv; P = 0.0001). No significant difference was found in subjective image quality, noise, signal-to-noise ratio, or contrast-to-noise ratio between the 2 groups.
  
  
  CONCLUSIONS
  AIDR reduced the tube current which resulted in reduction of radiation dose in coronary CTA while maintaining subjective and objective image quality compared with coronary CTA reconstructed with FBP.
authors.affiliation: Department of Radiology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. tomizawa-tky@umin.ac.jp
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tomizawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nojo
authors.forename: Masaaki
authors.initials: M
authors.lastname: Akahane
authors.forename: Rumiko
authors.initials: R
authors.lastname: Torigoe
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kiryu
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007479:Iopamidol; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D003287:Contrast Media; D007479:Iopamidol