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| #REDIRECT [[X-rays]] | | #REDIRECT [[X-rays]] |
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| ==Medical uses==
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| [[Image:X-Ray Skull.jpg|right|thumb|150px||X-Ray Image of the Paranasal Sinuses, Lateral Projection]]
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| Since Röntgen's discovery that X-rays can identify bony structures, X-rays have been developed for their use in [[medical imaging]]. [[Radiology]] is a specialized field of [[medicine]]. Radiographers employ [[radiography]] and other techniques for [[diagnostic imaging]]. Indeed, this is probably the most common use of X-ray technology.
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| X-rays are especially useful in the detection of pathology of the [[bone|skeletal system]], but are also useful for detecting some disease processes in [[soft tissue]]. Some notable examples are the very common [[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 [[ileus]] (blockage of the [[intestine]]), free air (from visceral perforations) and free fluid (in [[ascites]]). In some cases, the use of X-rays is debatable, such as [[gallstone]]s (which are rarely [[radiopaque]]) or [[kidney stone]]s (which are often visible, but not always). Also, traditional plain X-rays pose very little use in the imaging of soft tissues such as the [[brain]] or [[muscle]]. Imaging alternatives for soft tissues are [[computed axial tomography]] (CAT or CT scanning), [[magnetic resonance imaging]] (MRI) or [[medical ultrasonography|ultrasound]]. Since 2005, X-rays are listed as a [[carcinogen]] by the U.S. government.<ref>[http://ntp.niehs.nih.gov/ntp/roc/toc11.html 11th Report on Carcinogens<!-- Bot generated title -->]</ref>
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| [[Radiotherapy]], a curative medical intervention, now used almost exclusively for [[cancer]], employs higher energies of radiation.
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| The efficiency of X-ray tubes is less than 2%. Most of the energy is used to heat up the anode.
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| ==Other uses==
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| Other notable uses of X-rays include
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| *[[X-ray crystallography]] in which the pattern produced by the [[diffraction]] of X-rays through the closely spaced lattice of atoms in a crystal is recorded and then analyzed to reveal the nature of that lattice. A related technique, [[fiber diffraction]], was used by [[Rosalind Franklin]] to discover the [[Double helix|double helical]] structure of [[DNA]]).<ref>{{cite book
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| | last = Kasai
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| | first = Nobutami
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| | authorlink =
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| | coauthors = Masao Kakudo
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| | title = X-ray diffraction by macromolecules
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| | publisher = Kodansha
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| | date = 2005
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| | location = Tokyo
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| | pages = pp291-2
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| | url =
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| | doi =
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| | id =
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| | isbn = 3540253173}}</ref>
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| *[[X-ray astronomy]], which is an observational branch of [[astronomy]], which deals with the study of X-ray emission from celestial objects.
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| *[[X-ray microscope|X-ray microscopic analysis]], which uses [[electromagnetic radiation]] in the soft X-ray band to produce images of very small objects.
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| *[[X-ray fluorescence]], a technique in which X-rays are generated within a specimen and detected. The outgoing energy of the X-ray can be used to identify the composition of the sample.
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| *Paintings are often X-rayed to reveal the [[underdrawing]] and [[pentimento|pentimenti]] or alterations in the course of painting, or by later restorers. Many [[pigment]]s such as [[lead white]] show well in X-ray photographs.
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| ==History==
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| Among the important early researchers in X-rays were Professor [[Ivan Pulyui]], Sir [[William Crookes]], [[Johann Wilhelm Hittorf]], [[Eugen Goldstein]], [[Heinrich Hertz]], [[Philipp Lenard]], [[Hermann von Helmholtz]], [[Nikola Tesla]], [[Thomas Edison]], [[Charles Glover Barkla]], [[Max von Laue]], and [[Wilhelm Conrad Röntgen]]. In a humorous case of hindsight, [[Lord Kelvin]] said "X-Rays are a hoax".
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| ===Johann Hittorf===
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| Physicist [[Johann Hittorf]] (1824 – 1914) observed [[vacuum tube|tubes]] with energy rays extending from a negative electrode. These rays produced a fluorescence when they hit the glass walls of the tubes. In 1876 the effect was named "[[cathode ray]]s" by [[Eugen Goldstein]], and today are known to be streams of [[electron]]s. Later, English physicist [[William Crookes]] investigated the effects of electric currents in gases at low pressure, and constructed what is called the [[Crookes tube]]. It is a glass cylinder mostly (but not completely) evacuated, containing electrodes for discharges of a high voltage electric current. He found, when he placed unexposed photographic plates near the tube, that some of them were flawed by shadows, though he did not investigate this effect. Crookes also noted that his cathode rays caused the glass walls of his tube to glow a dull blue colour. Crookes failed to realise that it wasn't actually the cathode rays that caused the blue glow, but the low-level X-rays produced when the cathode rays struck the glass.
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| {{clear}}
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| ===Ivan Pulyui===
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| In 1877 [[Ukrane|Ukranian]]-born [[Ivan Pulyui|Pulyui]], a lecturer in experimental physics at the [[University of Vienna]], constructed various designs of [[Geissler tube|vacuum discharge tube]] to investigate their properties.<ref name=mayo>{{cite web
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| | last = Gaida
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| | first = Roman
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| | authorlink =
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| | coauthors = et al
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| | title = Ukrainian Physicist Contributes to the Discovery of X-Rays
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| | work =
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| | publisher = [[Mayo Clinic|Mayo Foundation for Medical Education and Research]]
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| | date = 1997
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| | url = http://www.meduniv.lviv.ua/oldsite/puluj.html
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| | format =
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| | doi =
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| | accessdate =2008-04-06 }}</ref> He continued his investigations when appointed professor at the [[Czech Technical University in Prague|Prague Polytechnic]] and in 1886 he found that that sealed photographic plates became dark when exposed to the emanations from the tubes. Early in 1896, just a few weeks after [[Wilhelm Conrad Röntgen|Röntgen]] published his first X-ray photograph, Pulyui published high-quality x-ray images in journals in Paris and London.<ref name=mayo/> Although Pulyui had studied with Röntgen at the [[University of Strasbourg]] in the years 1873-75, his biographer Gaida (1997) asserts that his subsequent research was conducted independently.<ref name=mayo/>
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| The first medical X-ray made in the United States was obtained using a discharge tube of Pulyui's design. In January 1896, on reading of Röntgen's discovery, Frank Austin of [[Dartmouth College]] tested all of the discharge tubes in the physics laboratory and found that only the Pulyui tube produced X-rays. This was a result of Pulyui's inclusion of an oblique "target" of [[mica]], used for holding samples of [[fluorescent]] material, within the tube. On [[3 February]] [[1896]] Gilman Frost, professor of medicine at the college, and his brother Edwin Frost, professor of physics, exposed the wrist of Eddie McCarthy, whom Edwin had treated some weeks earlier for a fracture, to the x-rays and collected the resulting image of the broken bone on [[Photographic plate|gelatin photographic plates]] obtained from Howard Langill, a local photographer also interested in Röntgen's work.<ref>{{cite journal
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| | last = Spiegel
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| | first = Peter K
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| | authorlink =
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| | coauthors =
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| | title = The first clinical X-ray made in America—100 years
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| | journal = American Journal of Roentgenology
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| | volume = 164
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| | issue = 1
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| | pages = pp241–243
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| | publisher = American Roentgen Ray Society
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| | location = Leesburg, VA
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| | date = 1995
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| | url = http://www.ajronline.org/cgi/reprint/164/1/241.pdf
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| | doi =
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| | id = ISSN: 1546-3141
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| | accessdate = }}</ref>
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| ===Nikola Tesla===
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| In April 1887, [[Nikola Tesla]] began to investigate X-rays using high voltages and tubes of his own design, as well as [[Crookes tube]]s. From his technical publications, it is indicated that he invented and developed a special single-electrode X-ray tube <ref>Morton, William James, and Edwin W. Hammer, American Technical Book Co., 1896. Page 68.</ref> <ref>{{US patent|514170}}, ''Incandescent Electric Light'', and {{US patent|454622}}, ''System of Electric Lighting''.</ref>, which differed from other X-ray tubes in having no target electrode. The principle behind Tesla's device is called the [[Bremsstrahlung]] process, in which a high-energy secondary X-ray emission is produced when charged particles (such as electrons) pass through matter. By 1892, Tesla performed several such experiments, but he did not categorize the emissions as what were later called X-rays. Tesla generalized the phenomenon as [[radiant energy]] of "invisible" kinds.<ref>Cheney, Margaret, "[http://books.google.com/books?vid=ISBN0743215362 Tesla: Man Out of Time ]". Simon and Schuster, 2001. Page 77.</ref> <ref>Thomas Commerford Martin (ed.), "[http://books.google.com/books?vid=OCLC04049568 The Inventions, Researches and Writings of Nikola Tesla]". Page 252 "When it forms a drop, it will emit visible and invisible waves. [...]". (ed., this material originally appeared in an article by Nikola Tesla in The Electrical Engineer of 1894.)</ref> Tesla stated the facts of his methods concerning various experiments in his 1897 X-ray lecture <ref>Nikola Tesla, "The stream of Lenard and Roentgen and novel apparatus for their production", Apr. 6, 1897.</ref> before the [[New York Academy of Sciences]]. Also in this lecture, Tesla stated the method of construction and safe operation of X-ray equipment. His X-ray experimentation by vacuum high field emissions also led him to alert the scientific community to the biological hazards associated with X-ray exposure.<ref>Cheney, Margaret, Robert Uth, and Jim Glenn, "[http://books.google.com/books?vid=ISBN0760710058 Tesla, master of lightning]". Barnes & Noble Publishing, 1999. Page 76. ISBN 0760710058</ref>
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