title: CT quality assurance in the lung screening study component of the National Lung Screening Trial: implications for multicenter imaging trials.
abstract: OBJECTIVE
  The purpose of this study was to describe the effect of implementing an imaging quality assurance program on CT image quality in the Lung Screening Study component of the National Lung Screening Trial.
  
  
  METHODS
  The National Lung Screening Trial is a multicenter study in which 53,457 subjects at increased risk of lung cancer were randomized to undergo three annual chest CT or radiographic screenings for lung cancer to determine the relative effect of use of the two screening tests on lung cancer mortality. Of the 26,724 subjects randomized to the CT screening arm of the National Lung Screening Trial, the Lung Screening Study randomized 17,309 through 10 screening centers. The others were randomized through the American College of Radiology Imaging Network. Quality assurance procedures were implemented that included centralized review of a random sample of 1,504 Lung Screening Study CT examinations. Quality defect rates were tabulated.
  
  
  RESULTS
  Quality defect rates ranged from 0% (section reconstruction interval) to 7.1% (reconstructed field of view), and most errors were sporadic. However, a recurrently high effective tube current-time product setting at one center, excessive streak artifact at one center, and excessive section thickness at one center were detected and corrected through the quality assurance process. Field-of-view and scan length errors were less frequent over the second half of the screening period (p < 0.01 for both parameters, two-tailed, paired Student's t test). Error rates varied among the screening centers and reviewers for most parameters evaluated.
  
  
  CONCLUSIONS
  Our experience suggested that centralized monitoring of image quality is helpful for reducing quality defects in multicenter trials.
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd., Campus Box 8131, St. Louis, MO 63105, USA. gieradad@wustl.edu
authors.forename: David S
authors.initials: DS
authors.lastname: Gierada
authors.forename: Kavita
authors.initials: K
authors.lastname: Garg
authors.forename: Hrudaya
authors.initials: H
authors.lastname: Nath
authors.forename: Diane C
authors.initials: DC
authors.lastname: Strollo
authors.forename: Richard M
authors.initials: RM
authors.lastname: Fagerstrom
authors.forename: Melissa B
authors.initials: MB
authors.lastname: Ford
mesh_terms: D016477:Artifacts; D002986:Clinical Trials as Topic / Q000592:standards; D003951:Diagnostic Errors / Q000517:prevention & control*; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality; D008403:Mass Screening / Q000592:standards*; D015337:Multicenter Studies as Topic / Q000592:standards; D011785:Quality Assurance, Health Care; D014057:Tomography, X-Ray Computed / Q000592:standards*