title: Assessment of Low-Contrast Resolution for the American College of Radiology Computed Tomographic Accreditation Program: What Is the Impact of Iterative Reconstruction?
abstract: OBJECTIVE
  To compare contrast-to-noise ratio (CNR) thresholds with visual assessment of low-contrast resolution (LCR) in filtered back projection (FBP) and iteratively reconstructed (IR) computed tomographic (CT) images.
  
  
  METHODS
  American College of Radiology (ACR) CT accreditation phantom LCR images were acquired at CTDIvol levels of 8, 12, and 16 mGy using 2 scanner models and reconstructed using one FBP and 2 IR kernels. Acquisitions were repeated 100 times. Three board-certified medical physicists blindly reviewed the LCR section images. Pass-percentage rates (PPRs) using previous and current ACR CT accreditation criteria were compared.
  
  
  RESULTS
  Observer PPRs for FBP images were less than 32%. For IR images, 5 of 18 settings/dose/model configurations had PPRs greater than 32% (maximum 76.3%). For CNR evaluation of FBP images, PPRs for 15 configurations were greater than 70%. For IR images, all PPRs were at least 96%.
  
  
  CONCLUSIONS
  The CNR threshold used by the ACR CT accreditation program yields higher PPRs than visual assessment of LCR, potentially resulting in lower-quality images passing the ACR CNR criteria.
authors: From the Departments of *Radiology and †Health Sciences Research, Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN.
authors: James M
authors: JM
authors: Kofler
authors: Lifeng
authors: L
authors: Yu
authors: Shuai
authors: S
authors: Leng
authors: Yi
authors: Y
authors: Zhang
authors: Zhoubo
authors: Z
authors: Li
authors: Rickey E
authors: RE
authors: Carter
authors: Cynthia H
authors: CH
authors: McCollough
mesh_terms: D000068:Accreditation / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D059629:Signal-To-Noise Ratio; D012955:Societies, Medical; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014481:United States