title: National variation of technical factors in computed tomography of the head.
abstract: OBJECTIVE
  The objectives of this study were to describe head computed tomography (CT) technical factors used in the United States; assess guideline compliance and variability by sex, geographic region, institution, and manufacturer; and compare with NEXT (Nationwide Evaluation of X-ray Trends) survey.
  
  
  METHODS
  Two thousand thirty-five head CT studies from 895 sites were analyzed. Peak kilovoltage, exposure, slice and image number, slice thickness, field of view, interslice gap, reformations, examination inclusiveness, use of contrast, and reconstruction filter were compared by sex, geographic region, institution type, and manufacturer.
  
  
  RESULTS
  One hundred twenty to 140 kVp (peak kilovoltage) was used by 99.8% of the sites. There was no correlation between mAs and kVp. There was a 30-fold increase in number of images and nearly 9-fold increase in number of slices from least to most. Nearly 4% use slice thickness and interslice gap greater than guidelines. There were significant regional differences in field of view, image number, and slice thickness. Some variation related to manufacturers was found. Minor difference was also found between academic and nonacademic institutions. There were significant differences in kVp and mAs compared with NEXT.
  
  
  CONCLUSIONS
  Significant variations in head CT technique exist in the United States.
authors.affiliation: vRAD, Eden Prairie, MN 55344, USA. David.Thickman@vrad.com
authors.forename: David
authors.initials: D
authors.lastname: Thickman
authors.forename: Guoqiao
authors.initials: G
authors.lastname: Wang
authors.forename: Jaleh
authors.initials: J
authors.lastname: White
authors.forename: Gary
authors.initials: G
authors.lastname: Cutter
mesh_terms: D001927:Brain Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D005260:Female; D019983:Guideline Adherence / Q000706:statistics & numerical data*; D006257:Head / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D015995:Prevalence; D011829:Radiation Dosage; D017678:Sex Distribution; D014057:Tomography, X-Ray Computed / Q000592:standards* / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology