National Trends in CT Use in the Emergency Department: 1995–2007

Published Online:

We found that use of CT in the emergency department in the United States has increased at a consistent exponential rate and at a rate higher than that reported in other settings.


To identify nationwide trends and factors associated with the use of computed tomography (CT) in the emergency department (ED).

Materials and Methods

This study was exempt from institutional review board approval. Data from the 1995–2007 National Hospital Ambulatory Medical Care Survey were used to evaluate the numbers and percentages of ED visits associated with CT. A mean of 30 044 visits were sampled each year. Data were also subcategorized according to multiple patient and hospital characteristics. The Rao-Scott χ2 test was performed to determine whether CT use was similar across subpopulations. Data were evaluated according to exponential and logistic growth models.


From 1995 to 2007, the number of ED visits that included a CT examination increased from 2.7 million to 16.2 million, constituting a 5.9-fold increase and a compound annual growth rate of 16.0%. The percentage of visits associated with CT increased from 2.8% to 13.9%, constituting a 4.9-fold increase and a compound annual growth rate of 14.2%. The exponential growth model provided the best fit for the trend in CT use. CT use was greater in older patients, white patients, patients admitted to the hospital, and patients at facilities in metropolitan regions. By the end of the study period, the top chief complaints among those who underwent CT were abdominal pain, headache, and chest pain. The percentage of patient visits associated with CT for all evaluated chief complaints increased—most substantially among those who underwent CT for flank, abdominal, or chest pain.


Use of CT has increased at a higher rate in the ED than in other settings. The overall use of CT had not begun to taper by 2007.

© RSNA, 2010

Supplemental material:


  • 1 Flohr TG, Schaller S, Stierstorfer K, Bruder H, Ohnesorge BM, Schoepf UJ. Multi-detector row CT systems and image-reconstruction techniques. Radiology 2005;235(3):756–773. LinkGoogle Scholar
  • 2 Broder J, Warshauer DM. Increasing utilization of computed tomography in the adult emergency department, 2000-2005. Emerg Radiol 2006;13(1):25–30. Crossref, MedlineGoogle Scholar
  • 3 Griffey RT, Ledbetter S, Khorasani R. Changes in thoracolumbar computed tomography and radiography utilization among trauma patients after deployment of multidetector computed tomography in the emergency department. J Trauma 2007;62(5):1153–1156. Crossref, MedlineGoogle Scholar
  • 4 IMV Medical Information Division. Benchmark report CT 2007. Des Plaines, Ill: IMV Medical Information Division, 2007. Google Scholar
  • 5 National Center for Health Statistics. Health, United States, 2009 with special feature on medical technology. U.S. Department of Health and Human Services Web site. Updated February 24, 2010. Accessed March 24, 2010. Google Scholar
  • 6 Smits M, Dippel DW, Nederkoorn PJet al.. Minor head injury: CT-based strategies for management—a cost-effectiveness analysis. Radiology 2010;254(2):532–540. LinkGoogle Scholar
  • 7 Babcock CR. Chest scan costs $550 to $3,232 in opaque market for radiology. Business Week Web site. Published March 4, 2010. Accessed March 24, 2010. Google Scholar
  • 8 National Council on Radiation Protection and Measurements. Ionizing radiation exposure of the population of the United States. NCRP report no. 160. Bethesda, Md: National Council on Radiation Protection, 2009. Google Scholar
  • 9 Berrington de González A, Mahesh M, Kim KPet al.. Projected cancer risks from computed tomographic scans performed in the United States in 2007. Arch Intern Med 2009;169(22):2071–2077. Crossref, MedlineGoogle Scholar
  • 10 Brenner DJ, Hall EJ. Computed tomography: an increasing source of radiation exposure. N Engl J Med 2007;357(22):2277–2284. Crossref, MedlineGoogle Scholar
  • 11 Lehnert BE, Bree RL. Analysis of appropriateness of outpatient CT and MRI referred from primary care clinics at an academic medical center: how critical is the need for improved decision support? J Am Coll Radiol 2010;7(3):192–197. Crossref, MedlineGoogle Scholar
  • 12 Iglehart JK. Health insurers and medical-imaging policy: a work in progress. N Engl J Med 2009;360(10):1030–1037. Crossref, MedlineGoogle Scholar
  • 13 Landro L. Radiation risks prompt push to curb CT scans. Wall Street Journal Web site. Published March 2, 2010. Accessed March 24, 2010. Google Scholar
  • 14 Protection of Human Subjects. Fed Regist 2009. Codified at 45 CFR §46.101(b)(4). Google Scholar
  • 15 Mahajan V, Peterson R. Models for innovation diffusion (quantitative applications in the social sciences). New Bury Park, Calif: Sage, 1985. CrossrefGoogle Scholar
  • 16 Cavallini F. Fitting a logistic curve to data. Coll Math J 1993;24(3):247–253. CrossrefGoogle Scholar
  • 17 Broder J, Bowen J, Lohr J, Babcock A, Yoon J. Cumulative CT exposures in emergency department patients evaluated for suspected renal colic. J Emerg Med 2007;33(2):161–168. Crossref, MedlineGoogle Scholar
  • 18 Blackwell CD, Gorelick M, Holmes JF, Bandyopadhyay S, Kuppermann N. Pediatric head trauma: changes in use of computed tomography in emergency departments in the United States over time. Ann Emerg Med 2007;49(3):320–324. Crossref, MedlineGoogle Scholar
  • 19 Mettler FA, Huda W, Yoshizumi TT, Mahesh M. Effective doses in radiology and diagnostic nuclear medicine: a catalog. Radiology 2008;248(1):254–263. LinkGoogle Scholar
  • 20 Brenner D, Elliston C, Hall E, Berdon W. Estimated risks of radiation-induced fatal cancer from pediatric CT. AJR Am J Roentgenol 2001;176(2):289–296. Crossref, MedlineGoogle Scholar
  • 21 Linton OW, Mettler FA; National Council on Radiation Protection and Measurements. National conference on dose reduction in CT, with an emphasis on pediatric patients. AJR Am J Roentgenol 2003;181(2):321–329. Crossref, MedlineGoogle Scholar
  • 22 Goske MJ, Applegate KE, Boylan Jet al.. The Image Gently Campaign: working together to change practice. AJR Am J Roentgenol 2008;190(2):273–274. Crossref, MedlineGoogle Scholar
  • 23 Salim A, Sangthong B, Martin M, Brown C, Plurad D, Demetriades D. Whole body imaging in blunt multisystem trauma patients without obvious signs of injury: results of a prospective study. Arch Surg 2006;141(5):468–473; discussion 473–475. Crossref, MedlineGoogle Scholar
  • 24 Huber-Wagner S, Lefering R, Qvick LMet al.. Effect of whole-body CT during trauma resuscitation on survival: a retrospective, multicentre study. Lancet 2009;373(9673):1455–1461. Crossref, MedlineGoogle Scholar
  • 25 Hadley JL, Agola J, Wong P. Potential impact of the American College of Radiology appropriateness criteria on CT for trauma. AJR Am J Roentgenol 2006;186(4):937–942. Crossref, MedlineGoogle Scholar
  • 26 Katz SI, Saluja S, Brink JA, Forman HP. Radiation dose associated with unenhanced CT for suspected renal colic: impact of repetitive studies. AJR Am J Roentgenol 2006;186(4):1120–1124. Crossref, MedlineGoogle Scholar
  • 27 Griffey RT, Sodickson A. Cumulative radiation exposure and cancer risk estimates in emergency department patients undergoing repeat or multiple CT. AJR Am J Roentgenol 2009;192(4):887–892. Crossref, MedlineGoogle Scholar
  • 28 Smith-Bindman R, Lipson J, Marcus Ret al.. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med 2009;169(22):2078–2086. Crossref, MedlineGoogle Scholar
  • 29 Broder J, Fordham LA, Warshauer DM. Increasing utilization of computed tomography in the pediatric emergency department, 2000-2006. Emerg Radiol 2007;14(4):227–232. Crossref, MedlineGoogle Scholar
  • 30 Levin DC, Rao VM, Parker L. Physician orders contribute to high-tech imaging slowdown. Health Aff (Millwood) 2010;29(1):189–195. Crossref, MedlineGoogle Scholar
  • 31 Smith-Bindman R, Miglioretti DL, Larson EB. Rising use of diagnostic medical imaging in a large integrated health system. Health Aff (Millwood) 2008;27(6):1491–1502. Crossref, MedlineGoogle Scholar
  • 32 Levin DC, Bree RL, Rao VM, Johnson J. A prior authorization program of a radiology benefits management company and how it has affected utilization of advanced diagnostic imaging. J Am Coll Radiol 2010;7(1):33–38. Crossref, MedlineGoogle Scholar
  • 33 Levin DC, Rao VM, Parker L, Frangos AJ, Sunshine JH. Recent shifts in place of service for noninvasive diagnostic imaging: have hospitals missed an opportunity? J Am Coll Radiol 2009;6(2):96–99. Crossref, MedlineGoogle Scholar
  • 34 Gralla J, Spycher F, Pignolet C, Ozdoba C, Vock P, Hoppe H. Evaluation of a 16-MDCT scanner in an emergency department: initial clinical experience and workflow analysis. AJR Am J Roentgenol 2005;185(1):232–238. Crossref, MedlineGoogle Scholar
  • 35 Kock MC, Adriaensen ME, Pattynama PMet al.. DSA versus multi-detector row CT angiography in peripheral arterial disease: randomized controlled trial. Radiology 2005;237(2):727–737. LinkGoogle Scholar
  • 36 Baker LC, Atlas SW, Afendulis CC. Expanded use of imaging technology and the challenge of measuring value. Health Aff (Millwood) 2008;27(6):1467–1478. Crossref, MedlineGoogle Scholar
  • 37 Katz DA, Williams GC, Brown RLet al.. Emergency physicians’ fear of malpractice in evaluating patients with possible acute cardiac ischemia. Ann Emerg Med 2005;46(6):525–533. Crossref, MedlineGoogle Scholar
  • 38 Iglehart JK. The new era of medical imaging: progress and pitfalls. N Engl J Med 2006;354(26):2822–2828. Crossref, MedlineGoogle Scholar
  • 39 Vartanians VM, Sistrom CL, Weilburg JB, Rosenthal DI, Thrall JH. Increasing the appropriateness of outpatient imaging: effects of a barrier to ordering low-yield examinations. Radiology 2010;255(3):842–849. LinkGoogle Scholar
  • 40 Amis ES, Butler PF, Applegate KEet al.. American College of Radiology white paper on radiation dose in medicine. J Am Coll Radiol 2007;4(5):272–284. Crossref, MedlineGoogle Scholar
  • 41 Dunnick NR, Applegate KE, Arenson RL. The inappropriate use of imaging studies: a report of the 2004 Intersociety Conference. J Am Coll Radiol 2005;2(5):401–406. Crossref, MedlineGoogle Scholar
  • 42 Bernardy M, Ullrich CG, Rawson JVet al.. Strategies for managing imaging utilization. J Am Coll Radiol 2009;6(12):844–850. Crossref, MedlineGoogle Scholar
  • 43 Haydel MJ, Preston CA, Mills TJ, Luber S, Blaudeau E, DeBlieux PM. Indications for computed tomography in patients with minor head injury. N Engl J Med 2000;343(2):100–105. Crossref, MedlineGoogle Scholar
  • 44 Stiell IG, Wells GA, Vandemheen Ket al.. The Canadian CT head rule for patients with minor head injury. Lancet 2001;357(9266):1391–1396. Crossref, MedlineGoogle Scholar
  • 45 Smits M, Dippel DW, de Haan GGet al.. Minor head injury: guidelines for the use of CT—a multicenter validation study. Radiology 2007;245(3):831–838. LinkGoogle Scholar

Article History

Received March 26, 2010; revision requested May 21; revision received June 22; final version accepted June 28.
Published online: Jan 2011
Published in print: Jan 2011