title: Noise-based tube current reduction method with iterative reconstruction for reduction of radiation exposure in coronary CT angiography.
abstract: OBJECTIVE
  To investigate the potential of noise-based tube current reduction method with iterative reconstruction to reduce radiation exposure while achieving consistent image quality in coronary CT angiography (CCTA).
  
  
  METHODS
  294 patients underwent CCTA on a 64-detector row CT equipped with iterative reconstruction. 102 patients with fixed tube current were assigned to Group 1, which was used to establish noise-based tube current modulation formulas, where tube current was modulated by the noise of test bolus image. 192 patients with noise-based tube current were randomly assigned to Group 2 and Group 3. Filtered back projection was applied for Group 2 and iterative reconstruction for Group 3. Qualitative image quality was assessed with a 5 point score. Image noise, signal intensity, volume CT dose index, and dose-length product were measured.
  
  
  RESULTS
  The noise-based tube current modulation formulas were established through regression analysis using image noise measurements in Group 1. Image noise was precisely maintained at the target value of 35.00 HU with small interquartile ranges for Group 2 (34.17-35.08 HU) and Group 3 (34.34-35.03 HU), while it was from 28.41 to 36.49 HU for Group 1. All images in the three groups were acceptable for diagnosis. A relative 14% and 41% reduction in effective dose for Group 2 and Group 3 were observed compared with Group 1.
  
  
  CONCLUSIONS
  Adequate image quality could be maintained at a desired and consistent noise level with overall 14% dose reduction using noise-based tube current reduction method. The use of iterative reconstruction further achieved approximately 40% reduction in effective dose.
authors.affiliation: Department of Radiology, Xuanwu Hospital of Capital Medical University, No. 45, Chang-Chun St., Xicheng District, Beijing 100053, China. shenjunlin8390@163.com
authors.forename: Junlin
authors.initials: J
authors.lastname: Shen
authors.forename: Xiangying
authors.initials: X
authors.lastname: Du
authors.forename: Daode
authors.initials: D
authors.lastname: Guo
authors.forename: Lizhen
authors.initials: L
authors.lastname: Cao
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.forename: Mei
authors.initials: M
authors.lastname: Bai
authors.forename: Pengyu
authors.initials: P
authors.lastname: Li
authors.forename: Jiabin
authors.initials: J
authors.lastname: Liu
authors.forename: Kuncheng
authors.initials: K
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001822:Body Burden; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*