Editing X-ray (section)

==Medical uses==
{{More citations needed|section|date=November 2017}}<!--"Projectional radiographs" and "Fluoroscopy" sections have no citations-->
[[File:Hospital Radiology Room Philips DigitalDiagnost Digital Radiography System.jpg|thumb|Patient undergoing an X-ray exam in a hospital radiology room]]
[[File:Radiografía pulmones Francisca Lorca.cropped.jpg|thumb|A [[chest radiograph]] of a female patient, demonstrating a [[hiatal hernia]]]]

Since Röntgen's discovery that X-rays can identify bone structures, X-rays have been used for [[medical imaging]].<ref name=Thomas2007>{{cite journal |last1=Thomas |first1=Adrian M.K. |title=The first 50 years of military radiology 1895–1945 |journal=European Journal of Radiology |date=August 2007 |volume=63 |issue=2 |pages=214–219 |doi=10.1016/j.ejrad.2007.05.024 |pmid=17629432 }}</ref> The first medical use was less than a month after his paper on the subject.<ref name="PKS" /> Up to 2010, five&nbsp;billion medical imaging examinations had been conducted worldwide.<ref name="Roobottom CA, Mitchell G, Morgan-Hughes G 2010 859–67">{{cite journal | vauthors = Roobottom CA, Mitchell G, Morgan-Hughes G | title = Radiation-reduction strategies in cardiac computed tomographic angiography | journal = Clinical Radiology | volume = 65 | issue = 11 | pages = 859–867 | date = November 2010 | pmid = 20933639 | doi = 10.1016/j.crad.2010.04.021 | quote = Of the 5 billion imaging investigations performed worldwide... | doi-access = free }}</ref> Radiation exposure from medical imaging in 2006 made up about 50% of total ionizing radiation exposure in the United States.<ref name=Science09/>

===Projectional radiographs===
{{Main|Projectional radiography}}
[[File:Knee plain X-ray.jpg|thumb|upright|Plain radiograph of the right knee]]

[[Projectional radiography]] is the practice of producing two-dimensional images using X-ray radiation. Bones contain a high concentration of [[calcium]], which, due to its relatively high [[atomic number]], absorbs X-rays efficiently. This reduces the amount of X-rays reaching the detector in the shadow of the bones, making them clearly visible on the radiograph. The lungs and trapped gas also show up clearly because of lower absorption compared to tissue, while differences between tissue types are harder to see.<ref>{{cite journal |last1=Rhinehart |first1=D. A. |title=Air and Gas in the Soft Tissues: A Radiologic Study |journal=Radiology |date=December 1931 |volume=17 |issue=6 |pages=1158–1170 |doi=10.1148/17.6.1158 }}</ref>

Projectional radiographs are useful in the detection of [[pathology]] of the [[bone|skeletal system]] as well as for detecting some disease processes in [[soft tissue]]. Some notable examples are the very common [[chest radiograph|chest X-ray]], which can be used to identify lung diseases such as [[pneumonia]], lung cancer, or [[pulmonary edema]], and the [[abdominal x-ray]], which can detect [[bowel obstruction|bowel (or intestinal) obstruction]], free air (from visceral perforations), and free fluid (in [[ascites]]). X-rays may also be used to detect pathology such as [[gallstone]]s (which are rarely [[radiodensity|radiopaque]]) or [[kidney stone]]s which are often (but not always) visible. Traditional plain X-rays are less useful in the imaging of soft tissues such as the brain or [[muscle]]. One area where projectional radiographs are used extensively is in evaluating how an orthopedic [[Implant (medicine)|implant]], such as a knee, hip or shoulder replacement, is situated in the body with respect to the surrounding bone. This can be assessed in two dimensions from plain radiographs, or it can be assessed in three dimensions if a technique called '2D to 3D registration' is used. This technique purportedly negates projection errors associated with evaluating implant position from plain radiographs.<ref>{{cite journal | vauthors = Van Haver A, Kolk S, DeBoodt S, Valkering K, Verdonk P |title=Accuracy of total knee implant position assessment based on postoperative X-rays, registered to pre-operative CT-based 3D models |journal=Orthopaedic Proceedings |url=http://bjjprocs.boneandjoint.org.uk/content/99-B/SUPP_4/80 |volume=99-B |number=Supp 4 |date=2018}}</ref>

[[Dental radiography]] is commonly used in the diagnoses of common oral problems, such as [[dental caries|cavities]].

In medical diagnostic applications, the low energy (soft) X-rays are unwanted, since they are totally absorbed by the body, increasing the radiation dose without contributing to the image. Hence, a thin metal sheet, often of aluminium, called an [[X-ray filter]], is usually placed over the window of the X-ray tube, absorbing the low energy part in the spectrum. This is called ''hardening'' the beam since it shifts the center of the spectrum towards higher energy (or harder) X-rays.

To generate an image of the [[Cardiovascular system#Human cardiovascular system|cardiovascular system]], including the arteries and veins ([[angiography]]) an initial image is taken of the anatomical region of interest. A second image is then taken of the same region after an iodinated [[Radiocontrast agent|contrast agent]] has been injected into the blood vessels within this area. These two images are then digitally subtracted, leaving an image of only the iodinated contrast outlining the blood vessels. The [[Radiology|radiologist]] or surgeon then compares the image obtained to normal anatomical images to determine whether there is any damage or blockage of the vessel.

===Computed tomography===
{{Main|CT scan}}
[[File:Brain CT scan.jpg|thumb|Head [[X-ray computed tomography|CT scan]] ([[transverse plane]]) slice – a modern application of [[medical radiography]]]]

[[Computed tomography]] (CT scanning) is a medical imaging modality where [[tomography|tomographic images]] or slices of specific areas of the body are obtained from a large series of two-dimensional X-ray images taken in different directions.<ref name="ref1">{{Cite book | vauthors = Herman GT |author-link=Gabor Herman |title= Fundamentals of Computerized Tomography: Image Reconstruction from Projections |date= 2009 |publisher= Springer |edition=2nd |isbn=978-1-85233-617-2 }}</ref> These cross-sectional images can be combined into a [[three-dimensional space|three-dimensional]] image of the inside of the body.<ref name=":0">{{cite book |last1=Hermena |first1=Shady |last2=Young |first2=Michael |title=StatPearls |date=2025 |publisher=StatPearls Publishing |chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK574548/ |chapter=CT-scan Image Production Procedures |pmid=34662062 }}</ref> CT scans are a quicker and more cost effective imaging modality that can be used for diagnostic and therapeutic purposes in various medical disciplines.<ref name=":0" />

===Fluoroscopy===
{{Main|Fluoroscopy}}

[[Fluoroscopy]] is an imaging technique commonly used by physicians or [[radiation therapist]]s to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope.<ref name=":1">{{cite journal |last1=Davros |first1=William J. |title=Fluoroscopy: basic science, optimal use, and patient/operator protection |journal=Techniques in Regional Anesthesia and Pain Management |date=April 2007 |volume=11 |issue=2 |pages=44–54 |doi=10.1053/j.trap.2007.02.005 }}</ref> In its simplest form, a fluoroscope consists of an X-ray source and a fluorescent screen, between which a patient is placed. However, modern fluoroscopes couple the screen to an [[X-ray image intensifier]] and [[charge-coupled device|CCD]] [[video camera]] allowing the images to be recorded and played on a monitor. This method may use a contrast material. Examples include cardiac catheterization (to examine for [[coronary circulation|coronary artery blockages]]), embolization procedures (to stop bleeding during [[hemorrhoidal artery embolization]]), and barium swallow (to examine for [[esophageal disorder]]s and swallowing disorders). As of recent, modern fluoroscopy utilizes short bursts of x-rays, rather than a continuous beam, to effectively lower radiation exposure for both the patient and operator.<ref name=":1" />

===Radiotherapy===
The use of X-rays as a treatment is known as [[radiation therapy]] and is largely used for the management (including [[palliation]]) of cancer; it requires higher radiation doses than those received for imaging alone. X-rays beams are used for treating skin cancers using lower energy X-ray beams while higher energy beams are used for treating cancers within the body such as brain, lung, prostate, and breast.<ref>Advances in kilovoltage x-ray beam dosimetry in {{cite journal | vauthors = Hill R, Healy B, Holloway L, Kuncic Z, Thwaites D, Baldock C | title = Advances in kilovoltage x-ray beam dosimetry | journal = Physics in Medicine and Biology | volume = 59 | issue = 6 | pages = R183–R231 | date = March 2014 | pmid = 24584183 | doi = 10.1088/0031-9155/59/6/r183 | bibcode = 2014PMB....59R.183H }}</ref><ref>{{cite journal | vauthors = Thwaites DI, Tuohy JB | title = Back to the future: the history and development of the clinical linear accelerator | journal = Physics in Medicine and Biology | volume = 51 | issue = 13 | pages = R343–R362 | date = July 2006 | pmid = 16790912 | doi = 10.1088/0031-9155/51/13/R20 | bibcode = 2006PMB....51R.343T }}</ref>