Editing CT scan (section)

=== Lungs ===
{{Main|Computed tomography of the chest}}
A CT scan can be used for detecting both acute and chronic changes in the [[Parenchyma#Lung parenchyma|lung parenchyma]], the tissue of the [[lung]]s.<ref>{{Cite book |url=https://books.google.com/books?id=rQlDDwAAQBAJ |title=Computed Tomography of the Lung |publisher=Springer Berlin Heidelberg |year=2007 |isbn=978-3-642-39518-5 |pages=40, 47}}</ref> It is particularly relevant here because normal two-dimensional X-rays do not show such defects. A variety of techniques are used, depending on the suspected abnormality. For evaluation of chronic interstitial processes such as [[Pneumatosis#Lungs|emphysema]], and [[Pulmonary fibrosis#|fibrosis]],<ref>{{Cite book |url=https://books.google.com/books?id=VKATAQAAMAAJ&q=ct+of+lungs |title=High-resolution CT of the Lung |publisher=Lippincott Williams & Wilkins |year=2009 |isbn=978-0-7817-6909-9 |pages=81,568}}</ref> thin sections with high spatial frequency reconstructions are used; often scans are performed both on inspiration and expiration. This special technique is called [[high resolution CT]] that produces a sampling of the lung, and not continuous images.<ref>{{Cite book |last1=Martínez-Jiménez |first1=Santiago |url=https://books.google.com/books?id=QjouDwAAQBAJ&q=HRCT |title=Specialty Imaging: HRCT of the Lung E-Book |last2=Rosado-de-Christenson |first2=Melissa L. |last3=Carter |first3=Brett W. |date=2017-07-22 |publisher=Elsevier Health Sciences |isbn=978-0-323-52495-7}}</ref>

[[File:High-resolution computed tomographs of a normal thorax (thumbnail).jpg|thumb|left|link=Commons:Scrollable high-resolution computed tomography images of a normal thorax|[[High-resolution computed tomography|HRCT]] images of a normal thorax in [[Axial plane|axial]], [[Coronal plane|coronal]] and [[sagittal plane]]s, respectively. {{noprint|[[Commons:Scrollable high-resolution computed tomography images of a normal thorax|Click here to scroll through the image stacks.]]}}|120x120px]]
[[File:Bronchial wall thickness (T) and diameter (D).svg|thumb|upright|Bronchial wall thickness (T) and diameter of the bronchus (D)]]
[[Peribronchial cuffing|Bronchial wall thickening]] can be seen on lung CTs and generally (but not always) implies inflammation of the [[bronchus|bronchi]].<ref>{{Cite web |last=Yuranga Weerakkody |title=Bronchial wall thickening |url=https://radiopaedia.org/articles/bronchial-wall-thickening |url-status=dead |archive-url=https://web.archive.org/web/20180106063640/https://radiopaedia.org/articles/bronchial-wall-thickening |archive-date=2018-01-06 |access-date=2018-01-05 |website=[[Radiopaedia]]}}</ref>

An [[Incidental medical findings|incidentally]] found nodule in the absence of symptoms (sometimes referred to as an [[incidentaloma]]) may raise concerns that it might represent a tumor, either [[Benignity|benign]] or [[cancer|malignant]].<ref>{{Cite journal |vauthors=Wiener RS, Gould MK, Woloshin S, Schwartz LM, Clark JA |year=2012 |title="What do you mean, a spot?": A qualitative analysis of patients' reactions to discussions with their doctors about pulmonary nodules |journal=Chest |volume=143 |issue=3 |pages=672–677 |doi=10.1378/chest.12-1095 |pmc=3590883 |pmid=22814873}}</ref> Perhaps persuaded by fear, patients and doctors sometimes agree to an intensive schedule of CT scans, sometimes up to every three months and beyond the recommended guidelines, in an attempt to do surveillance on the nodules.<ref name="ACCPandATSfive">{{Citation |last1=American College of Chest Physicians |title=Five Things Physicians and Patients Should Question |date=September 2013 |url=http://www.choosingwisely.org/doctor-patient-lists/american-college-of-chest-physicians-and-american-thoracic-society/ |work=[[Choosing Wisely]] |archive-url=https://web.archive.org/web/20131103063427/http://www.choosingwisely.org/doctor-patient-lists/american-college-of-chest-physicians-and-american-thoracic-society/ |publisher=American College of Chest Physicians and American Thoracic Society |access-date=6 January 2013 |archive-date=3 November 2013 |last2=American Thoracic Society |author-link=American College of Chest Physicians |author-link2=American Thoracic Society |url-status=live}}, which cites
*{{cite journal |vauthors=MacMahon H, Austin JH, Gamsu G, Herold CJ, Jett JR, Naidich DP, Patz EF, Swensen SJ |s2cid=14498160 |title=Guidelines for Management of Small Pulmonary Nodules Detected on CT Scans: A Statement from the Fleischner Society1 |journal=Radiology |volume=237 |issue=2 |pages=395–400 |year=2005 |pmid=16244247 |doi=10.1148/radiol.2372041887}}
*{{cite journal |vauthors = Gould MK, Fletcher J, Iannettoni MD, Lynch WR, Midthun DE, Naidich DP, Ost DE |title=Evaluation of Patients with Pulmonary Nodules: When is It Lung Cancer?* |journal=Chest |volume=132 |issue=3_suppl |pages=108S–130S |year=2007 |pmid=17873164 |doi=10.1378/chest.07-1353 |author8=American College of Chest Physicians |s2cid=16449420}}
*{{cite journal |vauthors=Smith-Bindman R, Lipson J, Marcus R, Kim KP, Mahesh M, Gould R, Berrington de González A, [[Diana Miglioretti|Miglioretti DL]] |title=Radiation Dose Associated with Common Computed Tomography Examinations and the Associated Lifetime Attributable Risk of Cancer |journal=Archives of Internal Medicine |volume=169 |issue=22 |pages=2078–2086 |year=2009 |pmid=20008690 |pmc=4635397 |doi=10.1001/archinternmed.2009.427 }}
*{{cite journal |vauthors=Wiener RS, Gould MK, Woloshin S, Schwartz LM, Clark JA |title="What do you mean, a spot?": A qualitative analysis of patients' reactions to discussions with their doctors about pulmonary nodules |journal=Chest |volume=143 |issue=3 |pages=672–677 |year=2012 |pmid=22814873 |pmc=3590883 |doi=10.1378/chest.12-1095}}</ref> However, established guidelines advise that patients without a prior history of cancer and whose solid nodules have not grown over a two-year period are unlikely to have any malignant cancer.<ref name="ACCPandATSfive" /> For this reason, and because no research provides supporting evidence that intensive surveillance gives better outcomes, and because of risks associated with having CT scans, patients should not receive CT screening in excess of those recommended by established guidelines.<ref name="ACCPandATSfive" />