Editing CT scan (section)

== Society and culture ==
{|class="wikitable floatright"
|+ Number of  CT scanners by country (OECD)<br />as of 2017<ref>{{Cite web |title=Computed tomography (CT) scanners |url=https://data.oecd.org/healtheqt/computed-tomography-ct-scanners.htm |publisher=OECD}}</ref><br />(per million population)
!Country !! Value
|-
|{{flagcountry| JPN}} || 111.49
|-
|{{flagcountry| AUS}} || 64.35
|-
|{{flagcountry| ISL}} || 43.68
|-
|{{flagcountry| USA}} || 42.64
|-
|{{flagcountry| DNK}} || 39.72
|-
|{{flagcountry| CHE}} || 39.28
|-
|{{flagcountry| LVA}} || 39.13
|-
|{{flagcountry| KOR}} || 38.18
|-
|{{flagcountry| DEU}} || 35.13
|-
|{{flagcountry| ITA}} || 34.71
|-
|{{flagcountry| GRC}} || 34.22
|-
|{{flagcountry| AUT}} || 28.64
|-
|{{flagcountry| FIN}} || 24.51
|-
|{{flagcountry| CHL}} || 24.27
|-
|{{flagcountry| LTU}} || 23.33
|-
|{{flagcountry| IRL}} || 19.14
|-
|{{flagcountry| ESP}} || 18.59
|-
|{{flagcountry| EST}} || 18.22
|-
|{{flagcountry| FRA}} || 17.36
|-
|{{flagcountry| SVK}} || 17.28
|-
|{{flagcountry| POL}} || 16.88
|-
|{{flagcountry| LUX}} || 16.77
|-
|{{flagcountry| NZL}} || 16.69
|-
|{{flagcountry| CZE}} || 15.76
|-
|{{flagcountry| CAN}} || 15.28
|-
|{{flagcountry| SVN}} || 15.00
|-
|{{flagcountry| TUR}} || 14.77
|-
|{{flagcountry| NLD}} || 13.48
|-
|{{flagcountry| RUS}} || 13.00
|-
|{{flagcountry| ISR}} || 9.53
|-
|{{flagcountry| HUN}} || 9.19
|-
|{{flagcountry| MEX}} || 5.83
|-
|{{flagcountry| COL}} || 1.24
|-
|}

=== Campaigns ===
In response to increased concern by the public and the ongoing progress of best practices, the Alliance for Radiation Safety in Pediatric Imaging was formed within the [[Society for Pediatric Radiology]]. In concert with the [[American Society of Radiologic Technologists]], the [[American College of Radiology]] and the [[American Association of Physicists in Medicine]], the Society for Pediatric Radiology developed and launched the Image Gently Campaign which is designed to maintain high-quality imaging studies while using the lowest doses and best radiation safety practices available on pediatric patients.<ref>{{Cite web |title=Image Gently |url=http://www.pedrad.org/associations/5364/ig/?page=365 |url-status=dead |archive-url=https://web.archive.org/web/20130609063515/http://www.pedrad.org/associations/5364/ig/?page=365 |archive-date=9 June 2013 |access-date=19 July 2013 |publisher=The Alliance for Radiation Safety in Pediatric Imaging}}</ref> This initiative has been endorsed and applied by a growing list of various professional medical organizations around the world and has received support and assistance from companies that manufacture equipment used in Radiology.

Following upon the success of the ''Image Gently'' campaign, the American College of Radiology, the Radiological Society of North America, the American Association of Physicists in Medicine and the American Society of Radiologic Technologists have launched a similar campaign to address this issue in the adult population called ''Image Wisely''.<ref>{{Cite web |title=Image Wisely |url=http://www.imagewisely.org/ |url-status=dead |archive-url=https://web.archive.org/web/20130721032437/http://imagewisely.org/ |archive-date=21 July 2013 |access-date=19 July 2013 |publisher=Joint Task Force on Adult Radiation Protection}}</ref>

The [[World Health Organization]] and [[International Atomic Energy Agency]] (IAEA) of the United Nations have also been working in this area and have ongoing projects designed to broaden best practices and lower patient radiation dose.<ref>{{Cite web |title=Optimal levels of radiation for patients |url=http://new.paho.org/hq10/index.php?option=com_content&task=view&id=3365&Itemid=2164 |url-status=dead |archive-url=https://web.archive.org/web/20130525051814/http://new.paho.org/hq10/index.php?option=com_content&task=view&id=3365&Itemid=2164 |archive-date=25 May 2013 |access-date=19 July 2013 |publisher=World Health Organization}}</ref><ref>{{Cite web |title=Global Initiative on Radiation Safety in Healthcare Settings |url=https://www.who.int/ionizing_radiation/about/GI_TM_Report_2008_Dec.pdf |url-status=live |archive-url=https://web.archive.org/web/20131029171805/http://www.who.int/ionizing_radiation/about/GI_TM_Report_2008_Dec.pdf |archive-date=29 October 2013 |access-date=19 July 2013 |publisher=World Health Organization}}</ref>

=== Prevalence ===

Use of CT has increased dramatically over the last two decades.<ref name="Smith2009" /> An estimated 72&nbsp;million scans were performed in the United States in 2007,<ref name="Berrington2009" /> accounting for close to half of the total per-capita dose rate from radiologic and nuclear medicine procedures.<ref>{{Cite journal |last1=Fred A. Mettler Jr |last2=Mythreyi Bhargavan |last3=Keith Faulkner |last4=Debbie B. Gilley |last5=Joel E. Gray |last6=Geoffrey S. Ibbott |last7=Jill A. Lipoti |last8=Mahadevappa Mahesh |last9=John L. McCrohan |last10=Michael G. Stabin |last11=Bruce R. Thomadsen |last12=Terry T. Yoshizumi |year=2009 |title=Radiologic and Nuclear Medicine Studies in the United States and Worldwide: Frequency, Radiation Dose, and Comparison with Other Radiation Sources — 1950-2007 |journal=Radiology |volume=253 |pages=520–531 |doi=10.1148/radiol.2532082010 |pmid=19789227 |number=2}}</ref> Of the CT scans, six to eleven percent are done in children,<ref name="Risk2011" /> an increase of seven to eightfold from 1980.<ref name="Furlow2010" /> Similar increases have been seen in Europe and Asia.<ref name="Furlow2010" /> In Calgary, Canada, 12.1% of people who present to the emergency with an urgent complaint received a CT scan, most commonly either of the head or of the abdomen. The percentage who received CT, however, varied markedly by the [[emergency physician]] who saw them from 1.8% to 25%.<ref>{{Cite journal |last=Andrew Skelly |date=Aug 3, 2010 |title=CT ordering all over the map |journal=The Medical Post}}</ref> In the emergency department in the United States, CT or [[Magnetic resonance imaging|MRI]] imaging is done in 15% of people who present with [[injuries]] as of 2007 (up from 6% in 1998).<ref>{{Cite journal |vauthors=Korley FK, Pham JC, Kirsch TD |date=October 2010 |title=Use of advanced radiology during visits to US emergency departments for injury-related conditions, 1998–2007 |journal=JAMA |volume=304 |issue=13 |pages=1465–71 |doi=10.1001/jama.2010.1408 |pmid=20924012 |doi-access=free|pmc=11660594 }}</ref>

The increased use of CT scans has been the greatest in two fields: screening of adults (screening CT of the lung in smokers, virtual colonoscopy, CT cardiac screening, and whole-body CT in asymptomatic patients) and CT imaging of children. Shortening of the scanning time to around 1 second, eliminating the strict need for the subject to remain still or be sedated, is one of the main reasons for the large increase in the pediatric population (especially for the diagnosis of [[appendicitis]]).<ref name="Brenner2007" /> As of 2007, in the United States a proportion of CT scans are performed unnecessarily.<ref name="Semelka2007">{{Cite journal |vauthors=Semelka RC, Armao DM, Elias J, Huda W |date=May 2007 |title=Imaging strategies to reduce the risk of radiation in CT studies, including selective substitution with MRI |journal=J Magn Reson Imaging |volume=25 |issue=5 |pages=900–9 |doi=10.1002/jmri.20895 |pmid=17457809 |s2cid=5788891|doi-access=free }}</ref> Some estimates place this number at 30%.<ref name="Risk2011" /> There are a number of reasons for this including: legal concerns, financial incentives, and desire by the public.<ref name="Semelka2007" /> For example, some healthy people avidly pay to receive full-body CT scans as [[screening (medicine)|screening]]. In that case, it is not at all clear that the benefits outweigh the risks and costs. Deciding whether and how to treat [[incidentaloma]]s is complex, radiation exposure is not negligible, and the money for the scans involves [[opportunity cost]].<ref name="Semelka2007" />