title: Evaluation of Low-Contrast Detectability of Iterative Reconstruction across Multiple Institutions, CT Scanner Manufacturers, and Radiation Exposure Levels.
abstract: OBJECTIVE
  To compare image resolution from iterative reconstruction with resolution from filtered back projection for low-contrast objects on phantom computed tomographic (CT) images across vendors and exposure levels.
  
  
  METHODS
  Randomized repeat scans of an American College of Radiology CT accreditation phantom (module 2, low contrast) were performed for multiple radiation exposures, vendors, and vendor iterative reconstruction algorithms. Eleven volunteers were presented with 900 images by using a custom-designed graphical user interface to perform a task created specifically for this reader study. Results were analyzed by using statistical graphics and analysis of variance.
  
  
  RESULTS
  Across three vendors (blinded as A, B, and C) and across three exposure levels, the mean correct classification rate was higher for iterative reconstruction than filtered back projection (P < .01): 87.4% iterative reconstruction and 81.3% filtered back projection at 20 mGy, 70.3% iterative reconstruction and 63.9% filtered back projection at 12 mGy, and 61.0% iterative reconstruction and 56.4% filtered back projection at 7.2 mGy. There was a significant difference in mean correct classification rate between vendor B and the other two vendors. Across all exposure levels, images obtained by using vendor B's scanner outperformed the other vendors, with a mean correct classification rate of 74.4%, while the mean correct classification rate for vendors A and C was 68.1% and 68.3%, respectively. Across all readers, the mean correct classification rate for iterative reconstruction (73.0%) was higher compared with the mean correct classification rate for filtered back projection (67.0%).
  
  
  CONCLUSIONS
  The potential exists to reduce radiation dose without compromising low-contrast detectability by using iterative reconstruction instead of filtered back projection. There is substantial variability across vendor reconstruction algorithms.
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Ganesh
authors.initials: G
authors.lastname: Saiprasad
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: James
authors.initials: J
authors.lastname: Filliben
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Adele
authors.initials: A
authors.lastname: Peskin
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Eliot
authors.initials: E
authors.lastname: Siegel
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Joseph
authors.initials: J
authors.lastname: Chen
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Christopher
authors.initials: C
authors.lastname: Trimble
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Zhitong
authors.initials: Z
authors.lastname: Yang
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Olav
authors.initials: O
authors.lastname: Christianson
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Ehsan
authors.initials: E
authors.lastname: Samei
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Krupinski
authors.affiliation: From the Software and Systems Division, National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305 (G.S., J.F., A.P., A.D.); Department of Diagnostic Radiology, University of Maryland Medical Center, Baltimore, Md (E. Siegel, J.C., C.T., Z.Y.); Departments of Medical Physics (O.C.) and Radiology (E. Samei), Duke University School of Medicine, Durham, NC; and Department of Radiology-Research, University of Arizona School of Medicine, Tucson, Ariz (E.K.).
authors.forename: Alden
authors.initials: A
authors.lastname: Dima
mesh_terms: D007091:Image Processing, Computer-Assisted; D019047:Phantoms, Imaging; D000069079:Radiation Exposure; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed