title: Use of computed tomography scanning before and after sitting in an emergency department.
abstract: OBJECTIVE
  Before a computed tomography (CT) scanner was installed in the emergency department, this hospital had no dedicated CT scanner for patients in the emergency department, and transporting these patients to the CT scanners in the radiology department took approximately 8-10 min each way. We sought to determine whether the presence of a CT scanner within the emergency department would lead to an increase in the number of emergent cranial CT examinations and a decrease in the diagnostic yield of these examinations.
  
  
  METHODS
  More than 8,000 records of cranial CT examinations were reviewed for the 12 months before and the 12 months after the installation of the CT scanner in the emergency department. A positive case was defined as one that showed acute abnormality such as ischemia, hemorrhage, edema, or mass effect.
  
  
  RESULTS
  Our results show a 30.1% increase in the number of CT scans of the head ordered by physicians in the emergency department after the installation of a CT scanner (p < .0001). This is compared with the background 1.8% increase in the total number of emergency department visits. However, in both periods, 12% of the total number of head scans done were positive.
  
  
  CONCLUSIONS
  The convenience of having a CT scanner in the emergency department leads to greater use of CT examinations. However, the increase in the number of emergent CT studies is justified because the number of positive CT examinations increases proportionately.
authors.affiliation: Department of Radiology, University of California, San Diego, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Chen
authors.forename: G S
authors.initials: GS
authors.lastname: Dorfman
authors.forename: M C
authors.initials: MC
authors.lastname: Li
authors.forename: J J
authors.initials: JJ
authors.lastname: Cronan
mesh_terms: D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D006257:Head / Q000000981:diagnostic imaging; D006801:Humans; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*