title: Quantitative analysis of the effect of iterative reconstruction using a phantom: determining the appropriate blending percentage.
abstract: OBJECTIVE
  To investigate the optimal blending percentage of adaptive statistical iterative reconstruction (ASIR) in a reduced radiation dose while preserving a degree of image quality and texture that is similar to that of standard-dose computed tomography (CT).
  
  
  METHODS
  The CT performance phantom was scanned with standard and dose reduction protocols including reduced mAs or kVp. Image quality parameters including noise, spatial, and low-contrast resolution, as well as image texture, were quantitatively evaluated after applying various blending percentages of ASIR. The optimal blending percentage of ASIR that preserved image quality and texture compared to standard dose CT was investigated in each radiation dose reduction protocol.
  
  
  RESULTS
  As the percentage of ASIR increased, noise and spatial-resolution decreased, whereas low-contrast resolution increased. In the texture analysis, an increasing percentage of ASIR resulted in an increase of angular second moment, inverse difference moment, and correlation and in a decrease of contrast and entropy. The 20% and 40% dose reduction protocols with 20% and 40% ASIR blending, respectively, resulted in an optimal quality of images with preservation of the image texture.
  
  
  CONCLUSIONS
  Blending the 40% ASIR to the 40% reduced tube-current product can maximize radiation dose reduction and preserve adequate image quality and texture.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hyun Gi
authors.initials: HG
authors.lastname: Kim
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea. yelv@yuhs.ac.
authors.forename: Yong Eun
authors.initials: YE
authors.lastname: Chung
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Choi
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Mi Suk
authors.initials: MS
authors.lastname: Park
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Myeong Jin
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Ki Whang
authors.initials: KW
authors.lastname: Kim
mesh_terms: D000465:Algorithms; D016477:Artifacts; D003287:Contrast Media; D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media
keywords: CT Image quality; filtered back projection; iterative reconstruction; radiation dose reduction; texture analysis