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overexposure incidents subsection</span> </button> <ul id="toc-Radiation_overexposure_incidents-sublist" class="vector-toc-list"> <li id="toc-Kennestone_Regional_Oncology_Center,_1985" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Kennestone_Regional_Oncology_Center,_1985"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Kennestone Regional Oncology Center, 1985</span> </div> </a> <ul id="toc-Kennestone_Regional_Oncology_Center,_1985-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Ontario_Cancer_Foundation,_1985" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Ontario_Cancer_Foundation,_1985"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Ontario Cancer Foundation, 1985</span> </div> </a> <ul id="toc-Ontario_Cancer_Foundation,_1985-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Yakima_Valley_Memorial_Hospital,_1985" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Yakima_Valley_Memorial_Hospital,_1985"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.3</span> <span>Yakima Valley Memorial Hospital, 1985</span> </div> </a> <ul id="toc-Yakima_Valley_Memorial_Hospital,_1985-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-East_Texas_Cancer_Center,_Tyler,_March_1986" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#East_Texas_Cancer_Center,_Tyler,_March_1986"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.4</span> <span>East Texas Cancer Center, Tyler, March 1986</span> </div> </a> <ul id="toc-East_Texas_Cancer_Center,_Tyler,_March_1986-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-East_Texas_Cancer_Center,_Tyler,_April_1986" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#East_Texas_Cancer_Center,_Tyler,_April_1986"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.5</span> <span>East Texas Cancer Center, Tyler, April 1986</span> </div> </a> <ul id="toc-East_Texas_Cancer_Center,_Tyler,_April_1986-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Yakima_Valley_Memorial_Hospital,_1987" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Yakima_Valley_Memorial_Hospital,_1987"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.6</span> <span>Yakima Valley Memorial Hospital, 1987</span> </div> </a> <ul id="toc-Yakima_Valley_Memorial_Hospital,_1987-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Root_causes" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Root_causes"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Root causes</span> </div> </a> <ul id="toc-Root_causes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> 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href="https://cs.wikipedia.org/wiki/Therac-25" title="Therac-25 – Czech" lang="cs" hreflang="cs" data-title="Therac-25" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Therac-25" title="Therac-25 – German" lang="de" hreflang="de" data-title="Therac-25" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Therac-25" title="Therac-25 – Spanish" lang="es" hreflang="es" data-title="Therac-25" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Therac-25" title="Therac-25 – French" lang="fr" hreflang="fr" data-title="Therac-25" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/Therac-25" title="Therac-25 – Korean" lang="ko" hreflang="ko" data-title="Therac-25" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Therac-25" title="Therac-25 – Italian" lang="it" hreflang="it" data-title="Therac-25" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Therac-25" title="Therac-25 – Lithuanian" lang="lt" hreflang="lt" data-title="Therac-25" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Therac-25" title="Therac-25 – Dutch" lang="nl" hreflang="nl" data-title="Therac-25" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%82%BB%E3%83%A9%E3%83%83%E3%82%AF25" title="セラック25 – Japanese" lang="ja" hreflang="ja" data-title="セラック25" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Therac-25" title="Therac-25 – Polish" lang="pl" hreflang="pl" data-title="Therac-25" data-language-autonym="Polski" 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class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Therac-25" title="Therac-25 – Swedish" lang="sv" hreflang="sv" data-title="Therac-25" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/Therac-25" title="Therac-25 – Ukrainian" lang="uk" hreflang="uk" data-title="Therac-25" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Therac-25" title="Therac-25 – Vietnamese" lang="vi" hreflang="vi" data-title="Therac-25" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng 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Unsourced material may be challenged and removed.<br /><small><span class="plainlinks"><i>Find sources:</i> <a rel="nofollow" class="external text" href="https://www.google.com/search?as_eq=wikipedia&q=%22Therac-25%22">"Therac-25"</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22Therac-25%22+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22Therac-25%22&tbs=bkt:s&tbm=bks">newspapers</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?tbs=bks:1&q=%22Therac-25%22+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22Therac-25%22">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22Therac-25%22&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">July 2023</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> </div> </div><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <p>The <b>Therac-25</b> is a computer-controlled <a href="/wiki/Radiation_therapy" title="Radiation therapy">radiation therapy</a> machine produced by <a href="/wiki/Atomic_Energy_of_Canada_Limited" title="Atomic Energy of Canada Limited">Atomic Energy of Canada Limited</a> (AECL) in 1982 after the Therac-6 and Therac-20 units (the earlier units had been produced in partnership with <span title="French-language text"><span lang="fr" style="font-style: normal;">Compagnie générale de radiologie (CGR)</span></span> of France).<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p><p>The Therac-25 was involved in at least six accidents between 1985 and 1987, in which some patients were given massive <a href="/wiki/Radiation_poisoning" class="mw-redirect" title="Radiation poisoning">overdoses of radiation</a>.<sup id="cite_ref-baase_2-0" class="reference"><a href="#cite_note-baase-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 425">: <a rel="nofollow" class="external text" href="https://archive.org/details/giftoffiresocial0000baas_r4k3/page/425/mode/2up">425</a> </span></sup> Because of <a href="/wiki/Race_condition" title="Race condition">concurrent programming errors</a> (also known as race conditions), it sometimes gave its patients radiation doses that were hundreds of times greater than normal, resulting in death or serious injury.<sup id="cite_ref-Raj_3-0" class="reference"><a href="#cite_note-Raj-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> These accidents highlighted the dangers of software <a href="/wiki/Control_system" title="Control system">control</a> of safety-critical systems. </p><p>The Therac-25 has become a standard case study in <a href="/wiki/Health_informatics" title="Health informatics">health informatics</a>, <a href="/wiki/Software_engineering" title="Software engineering">software engineering</a>, and <a href="/wiki/Computer_ethics" title="Computer ethics">computer ethics</a>. It highlights the dangers of engineer overconfidence<sup id="cite_ref-baase_2-1" class="reference"><a href="#cite_note-baase-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 428">: <a rel="nofollow" class="external text" href="https://archive.org/details/giftoffiresocial0000baas_r4k3/page/428/mode/2up">428</a> </span></sup> after the engineers dismissed end-user reports, leading to severe consequences. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Medical_Linac.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Medical_Linac.svg/220px-Medical_Linac.svg.png" decoding="async" width="220" height="311" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Medical_Linac.svg/330px-Medical_Linac.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Medical_Linac.svg/440px-Medical_Linac.svg.png 2x" data-file-width="744" data-file-height="1052" /></a><figcaption>Linear accelerator</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Medical_Linac_Animation.gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Medical_Linac_Animation.gif/220px-Medical_Linac_Animation.gif" decoding="async" width="220" height="312" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Medical_Linac_Animation.gif/330px-Medical_Linac_Animation.gif 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Medical_Linac_Animation.gif/440px-Medical_Linac_Animation.gif 2x" data-file-width="508" data-file-height="720" /></a><figcaption>Animation of the operation of a medical use linear accelerator</figcaption></figure> <p>The French company CGR manufactured the <i>Neptune</i> and <i>Sagittaire</i> linear accelerators. </p><p>In the early 1970s, CGR and the Canadian public company <i>Atomic Energy of Canada Limited</i> (AECL) collaborated on the construction of linear accelerators controlled by a DEC <a href="/wiki/PDP-11" title="PDP-11">PDP-11</a> minicomputer: the Therac-6, which produced X-rays of up to 6 MeV, and the Therac-20, which could produce X-rays or electrons of up to 20 MeV. The computer increased ease of use because the accelerator could operate without it. CGR developed the software for the Therac-6 and reused some subroutines for the Therac-20.<sup id="cite_ref-ComputerMagazine_4-0" class="reference"><a href="#cite_note-ComputerMagazine-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>In 1981, the two companies ended their collaboration agreement. AECL developed a new double pass concept for electron acceleration in a more confined space, changing its energy source from <a href="/wiki/Klystron" title="Klystron">klystron</a> to <a href="/wiki/Magnetron" class="mw-redirect" title="Magnetron">magnetron</a>. In certain techniques, the electrons produced are used directly, while in others they are made to collide against a tungsten anode to produce X-ray beams. This dual accelerator concept was applied to the Therac-20 and Therac-25, with the latter being much more compact, versatile, and easy to use. It was also more economical for a hospital to have a dual machine that could apply treatments of electrons and X-rays, instead of two machines. </p><p>The Therac-25 was designed as a machine controlled by a computer, with some safety mechanisms switched from hardware to software as a result. AECL decided not to duplicate some safety mechanisms, and reused modules and code routines from the Therac-20 for the Therac-25. </p><p>The first prototype of the Therac-25 was built in 1976 and was put on the market in late 1982. </p><p>The software for the Therac-25 was developed by one person over several years using PDP-11 assembly language. It was an evolution of the Therac-6 software. In 1986, the programmer left AECL. In a subsequent lawsuit, lawyers were unable to identify the programmer or learn about his qualification and experience. </p><p>Six machines were installed in Canada and five in the United States.<sup id="cite_ref-ComputerMagazine_4-1" class="reference"><a href="#cite_note-ComputerMagazine-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>After the accidents, in 1988 AECL dissolved the <i>AECL Medical</i> section and the company <i>Theratronics International Ltd</i> took over the maintenance of the installed Therac-25 machines.<sup id="cite_ref-Barbara_5-0" class="reference"><a href="#cite_note-Barbara-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Design">Design</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=2" title="Edit section: Design"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The machine had three modes of operation, with a turntable moving some apparatus into position for each of those modes: either a light, some <i>scan magnets</i>, or a tungsten target and <i>flattener</i>.<sup id="cite_ref-Safeware_6-0" class="reference"><a href="#cite_note-Safeware-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <ul><li>A "field light" mode, which allowed the patient and <a href="/wiki/Collimator" title="Collimator">collimator</a> to be correctly positioned by illuminating the treatment area with visible light.</li> <li>Direct <a href="/wiki/Electron_therapy" title="Electron therapy">electron-beam therapy</a>, in which a narrow, low-current beam of high-energy (5 to 25 <a href="/wiki/Electronvolt" title="Electronvolt">MeV</a> (0.80 to 4.01 <a href="/wiki/Joule" title="Joule">pJ</a>)) electrons was scanned over the treatment area by magnets;<sup id="cite_ref-Safeware_6-1" class="reference"><a href="#cite_note-Safeware-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Megavoltage_X-rays" title="Megavoltage X-rays">Megavolt X-ray</a> (or photon) therapy, which delivered a beam of 25 MeV <a href="/wiki/X-ray" title="X-ray">X-ray</a> photons. The X-ray photons are produced by colliding a high current, narrow beam of electrons with a <a href="/wiki/Tungsten" title="Tungsten">tungsten</a> target. The X-rays are then passed through a flattening filter, and then measured using an X-ray <a href="/wiki/Ion_chamber" class="mw-redirect" title="Ion chamber">ion chamber</a>. The flattening filter resembles an inverted ice-cream cone, and it shapes and attenuates the X-rays. The electron beam current required to produce the X-rays is about 100 times greater than that used for electron therapy.<sup id="cite_ref-Safeware_6-2" class="reference"><a href="#cite_note-Safeware-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup></li></ul> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Therac_25_Rotation.gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Therac_25_Rotation.gif/250px-Therac_25_Rotation.gif" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Therac_25_Rotation.gif/330px-Therac_25_Rotation.gif 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Therac_25_Rotation.gif/500px-Therac_25_Rotation.gif 2x" data-file-width="980" data-file-height="656" /></a><figcaption>Turntable rotation</figcaption></figure> <p>The patient is placed on a fixed stretcher. Above them is a turntable to which the components that modify the electron beam are fixed. The turntable has a position for the X-ray mode (photons), another position for the electron mode and a third position for making adjustments using visible light. In this position an electron beam is not expected, and a light that is reflected in a stainless steel mirror simulates the beam. In this position there is no ion chamber acting as a radiation dosimeter because the radiation beam is not expected to function. </p><p>The turntable has some <a href="/wiki/Miniature_snap-action_switch" title="Miniature snap-action switch">microswitches</a> that indicate the position to the computer. When the plate is in one of the three allowed fixed positions a plunger locks it by <a href="/wiki/Interlock_(engineering)" title="Interlock (engineering)">interlocking</a>. In this type of machine, electromechanical locks were traditionally used to ensure that the turntable was in the correct position before starting treatment. In the Therac-25, these were replaced by software checks.<sup id="cite_ref-Safeware_6-3" class="reference"><a href="#cite_note-Safeware-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Problem_description">Problem description</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=3" title="Edit section: Problem description"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Therac25_Interface.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/90/Therac25_Interface.png/250px-Therac25_Interface.png" decoding="async" width="220" height="132" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/90/Therac25_Interface.png/330px-Therac25_Interface.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/90/Therac25_Interface.png/500px-Therac25_Interface.png 2x" data-file-width="642" data-file-height="386" /></a><figcaption>Simulated Therac-25 user interface</figcaption></figure> <p>The six documented accidents occurred when the high-current electron beam generated in X-ray mode was delivered directly to patients. Two software faults were to blame.<sup id="cite_ref-Safeware_6-4" class="reference"><a href="#cite_note-Safeware-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> One was when the operator incorrectly selected X-ray mode before quickly changing to electron mode, which allowed the electron beam to be set for X-ray mode without the X-ray target being in place. A second fault allowed the electron beam to activate during field-light mode, during which no beam scanner was active or target was in place. </p><p>Previous models had hardware interlocks to prevent such faults, but the Therac-25 had removed them, depending instead on software checks for safety. </p><p>The high-current electron beam struck the patients with approximately 100 times the intended dose of radiation, and over a narrower area, delivering a potentially lethal dose of <a href="/wiki/Beta_radiation" class="mw-redirect" title="Beta radiation">beta radiation</a>. The feeling was described by patient Ray Cox as "an intense electric shock", causing him to scream and run out of the treatment room.<sup id="cite_ref-Phasers_On_Stun_pp11-16_7-0" class="reference"><a href="#cite_note-Phasers_On_Stun_pp11-16-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Several days later, <a href="/wiki/Radiation_burn" title="Radiation burn">radiation burns</a> appeared, and the patients showed the symptoms of <a href="/wiki/Radiation_poisoning" class="mw-redirect" title="Radiation poisoning">radiation poisoning</a>; in three cases, the injured patients later died as a result of the overdose.<sup id="cite_ref-Rose_1994_8-0" class="reference"><a href="#cite_note-Rose_1994-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Radiation_overexposure_incidents">Radiation overexposure incidents</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=4" title="Edit section: Radiation overexposure incidents"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Kennestone_Regional_Oncology_Center,_1985"><span id="Kennestone_Regional_Oncology_Center.2C_1985"></span>Kennestone Regional Oncology Center, 1985</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=5" title="Edit section: Kennestone Regional Oncology Center, 1985"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A Therac-25 had been in operation for six months in <a href="/wiki/Marietta,_Georgia" title="Marietta, Georgia">Marietta, Georgia</a> at the Kennestone Regional Oncology Center when, on June 3, 1985, applied radiation therapy treatment following a <a href="/wiki/Lumpectomy" title="Lumpectomy">lumpectomy</a> was being performed on 61-year-old woman Katie Yarbrough. She was set to receive a 10-MeV dose of electron therapy to her <a href="/wiki/Clavicle" title="Clavicle">clavicle</a>. When therapy began, she stated she experienced a "tremendous force of heat...this red-hot sensation." The technician entered the room, to whom Katie stated, "you burned me." The technician assured her this was not possible. She returned home where, in the following days, she experienced reddening of the treatment area. Shortly after, her shoulder became locked in place and she experienced spasms. Within two weeks, the aforementioned redness spread from her chest to her back, indicating that the source of the burn had passed through her, which is the case with radiation burns. The staff at the treatment center did not believe it was possible for the Therac-25 to cause such an injury, and it was treated as a symptom of her <a href="/wiki/Cancer" title="Cancer">cancer</a>. Later, the hospital physicist consulted the AECL about the incident. He calculated that the applied dose was between 15,000 and 20,000 <a href="/wiki/Rad_(radiation_unit)" title="Rad (radiation unit)">rad</a> when she should have been dosed with 200 rad. A dose of 1000 rad can be fatal. In October 1985, Katie sued the hospital and the manufacturer of the machine. In November 1985, the AECL was notified of the lawsuit. It was not until March 1986, after another incident involving the Therac-25, that the AECL informed the FDA that it had received a complaint from the patient. </p><p>Due to the radiation overdose, her breast had to be surgically removed, an arm and shoulder were immobilized, and she was in constant pain. The treatment printout function was not activated at the time of treatment and there was no record of the applied radiation data. An out-of-court settlement was reached to resolve the lawsuit.<sup id="cite_ref-Raj_3-1" class="reference"><a href="#cite_note-Raj-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Ontario_Cancer_Foundation,_1985"><span id="Ontario_Cancer_Foundation.2C_1985"></span>Ontario Cancer Foundation, 1985</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=6" title="Edit section: Ontario Cancer Foundation, 1985"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Terminal-dec-vt100.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Terminal-dec-vt100.jpg/250px-Terminal-dec-vt100.jpg" decoding="async" width="220" height="173" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Terminal-dec-vt100.jpg/330px-Terminal-dec-vt100.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Terminal-dec-vt100.jpg/500px-Terminal-dec-vt100.jpg 2x" data-file-width="640" data-file-height="502" /></a><figcaption>DEC <a href="/wiki/VT100" title="VT100">VT100</a> video <a href="/wiki/Computer_terminal" title="Computer terminal">computer terminal</a></figcaption></figure> <p>The Therac-25 had been in operation in the clinic for six months when, on July 26, 1985, a 40-year-old patient was receiving her 24th treatment for <a href="/wiki/Cervical_cancer" title="Cervical cancer">cervical cancer</a>. The operator activated the treatment, but after five seconds the machine stopped with the error message "H-tilt", the treatment pause indication and the dosimeter indicating that no radiation had been applied. The operator pressed the <style data-mw-deduplicate="TemplateStyles:r1249182868">.mw-parser-output .keyboard-key{border:1px solid #aaa;border-radius:0.2em;box-shadow:0.1em 0.1em 0.2em rgba(0,0,0,0.1);background-color:var(--background-color-neutral-subtle,#f8f9fa);background-image:linear-gradient(to bottom,var(--background-color-neutral,#eaecf0),var(--background-color-neutral-subtle,#f8f9fa),var(--background-color-neutral,#eaecf0));color:var(--color-base,#202122);padding:0.1em 0.3em;font-family:inherit;font-size:0.85em}</style><kbd class="keyboard-key nowrap">P</kbd> key (Proceed : continue). The machine stopped again. The operator repeated the process five times until the machine stopped the treatment. A technician was called and found no problem. The machine was used to treat six other patients on the same day. </p><p>The patient complained of burning and swelling in the area and was hospitalized on July 30. She was suspected of a radiation overdose and the machine was taken out of service. On November 3, 1985, the patient died of cancer, although the autopsy mentioned that if she had not died then, she would have had to undergo a hip replacement due to damage from the radiation overdose. A technician estimated that she received between 13,000 and 17,000 rad. </p><p>The incident was reported to the FDA and the Canadian Radiation Protection Bureau. </p><p>The AECL suspected that there might be an error with three microswitches that reported the position of the turntable. The AECL was unable to replicate a failure of the microswitches and microswitch testing was inconclusive. They then changed the method to be tolerant of one failure and modified the software to check if the turntable was moving or in the treatment position. </p><p>Afterward, the AECL claimed that the modifications represented a five-order-of-magnitude increase in safety.<sup id="cite_ref-Raj_3-2" class="reference"><a href="#cite_note-Raj-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Yakima_Valley_Memorial_Hospital,_1985"><span id="Yakima_Valley_Memorial_Hospital.2C_1985"></span>Yakima Valley Memorial Hospital, 1985</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=7" title="Edit section: Yakima Valley Memorial Hospital, 1985"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In December 1985 a woman developed an <a href="/wiki/Erythema" title="Erythema">erythema</a> with a parallel band pattern after receiving treatment from a Therac-25 unit. Hospital staff sent a letter on January 31, 1986, to the AECL about the incident. The AECL responded in two pages detailing the reasons why radiation overdose was impossible on the Therac-25, stating both machine failure and operator error were not possible. </p><p>Six months later, the patient developed chronic ulcers under the skin due to tissue necrosis. She had surgery and skin grafts were placed. The patient continued to live with minor <a href="/wiki/Sequela" title="Sequela">sequelae</a>.<sup id="cite_ref-Raj_3-3" class="reference"><a href="#cite_note-Raj-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="East_Texas_Cancer_Center,_Tyler,_March_1986"><span id="East_Texas_Cancer_Center.2C_Tyler.2C_March_1986"></span>East Texas Cancer Center, Tyler, March 1986</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=8" title="Edit section: East Texas Cancer Center, Tyler, March 1986"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Over two years, this hospital treated more than 500 patients with the Therac-25 with no incident. On March 21, 1986, a patient presented for his ninth treatment session for a tumor on his back. The treatment was set to be 22-MeV of electrons with a dose of 180 rad in an area of 10x17 cm, with an accumulated radiation in 6 weeks of 6000 rad. </p><p>The experienced operator entered the session data and realized that she had written an “X” for ‘X-ray’ instead of an “E” for ‘electron beam’ as the type of treatment. With the cursor she went up and changed the “X” to an “E” and since the rest of the parameters were correct she pressed <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">↵ Enter</kbd> until she got down to the command box. All parameters were marked "Verified" and the message "Rays ready" was displayed. She hit the <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">B</kbd> key ("Beam on"). The machine stopped and displayed the message "Malfunction 54" (error 54). It also showed 'Treatment pause'. The manual said that the "Malfunction 54" message was a "dose input 2" error. A technician later testified that "dose input 2" meant that the radiation delivered was either too high or too low. </p><p>The radiation monitor (dosimeter) marked 6 units supplied when it had demanded 202 units. The operator pressed <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">P</kbd> ( Proceed : continue). The machine stopped again with the message "Malfunction 54" (error 54) and the dosimeter indicated that it had delivered fewer units than required. The surveillance camera in the radiation room was offline and the intercom had been broken that day. </p><p>With the first dose the patient felt an electric shock and heard a crackle from the machine. Since it was his ninth session, he realized that it was not normal. He started to get up from the table to ask for help. At that moment the operator pressed <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">P</kbd> to continue the treatment. The patient felt a shock of electricity through his arm, as if his hand was torn off. He reached the door and began to bang on it until the operator opened it. A physician was immediately called to the scene, where they observed intense <a href="/wiki/Erythema" title="Erythema">erythema</a> in the area, suspecting that it had been a simple electric shock. He sent the patient home. The hospital physicist checked the machine and, because it was calibrated to the correct specification, it continued to treat patients throughout the day. The technicians were unaware that the patient had received a massive dose of radiation between 16,500 and 25,000 rads in less than a second over an area of one cm<sup>2</sup>. The crackling of the machine had been produced by saturation of the ionization chambers, which had the consequence that they indicated that the applied radiation dose had been very low. </p><p>Over the following weeks the patient experienced paralysis of the left arm, nausea, vomiting, and ended up being hospitalized for radiation-induced <a href="/wiki/Myelitis" title="Myelitis">myelitis</a> of the spinal cord. His legs, mid-diaphragm and vocal cords ended up paralyzed. He also had recurrent herpes simplex skin infections. He died five months after the overdose. </p><p>From the day after the accident, AECL technicians checked the machine and were unable to replicate error 54. They checked the grounding of the machine to rule out electric shock as the cause. The machine was back in operation on April 7, 1986.<sup id="cite_ref-Raj_3-4" class="reference"><a href="#cite_note-Raj-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="East_Texas_Cancer_Center,_Tyler,_April_1986"><span id="East_Texas_Cancer_Center.2C_Tyler.2C_April_1986"></span>East Texas Cancer Center, Tyler, April 1986</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=9" title="Edit section: East Texas Cancer Center, Tyler, April 1986"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>On April 11, 1986, a patient was to receive electron treatment for skin cancer on the face. The prescription was 10 MeV for an area of 7x10 cm. The operator was the same as the one in the March incident, three weeks earlier. After filling in all the treatment data she realized that she had to change the mode from X to E. She did so and pressed <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">↵ Enter</kbd> to go down to the command box. As "Beam ready" was displayed, she pressed <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">P</kbd> (Proceed : continue). The machine produced a loud noise, which was heard through the intercom. Error 54 was displayed. The operator entered the room and the patient described a burning sensation on his face. The patient died on May 1, 1986, just shy of 3 weeks later. The autopsy showed severe radiation damage to the right temporal lobe and brain stem. </p><p>The hospital physicist stopped the machine treatments and notified the AECL. After strenuous work, the physicist and operator were able to reproduce the error 54 message. They determined that speed in editing the data entry was a key factor in producing error 54. After much practice, he was able to reproduce the error 54 at will. The AECL stated they could not reproduce the error and they only got it after following the instructions of the physicist so that the data entry was very rapid.<sup id="cite_ref-Raj_3-5" class="reference"><a href="#cite_note-Raj-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Yakima_Valley_Memorial_Hospital,_1987"><span id="Yakima_Valley_Memorial_Hospital.2C_1987"></span>Yakima Valley Memorial Hospital, 1987</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=10" title="Edit section: Yakima Valley Memorial Hospital, 1987"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>On January 17, 1987, a patient was to receive a treatment with two film-verification exposures of 4 and 3 rad, plus a 79-rad photon treatment for a total exposure of 86 rad. Film was placed under the patient and 4 rad were administered through a 22 cm × 18 cm opening. The machine was stopped, the aperture was opened to 35 cm × 35 cm and a dose of 3 rad was administered. The machine stopped. The operator entered the room to remove the film plates and adjust the patient's position. He used the hand control inside the room to adjust the turntable. He left the room, forgetting the film plates. In the control room, after seeing the "Beam ready" message, he pressed the <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">B</kbd> key to fire the beams. After 5 seconds the machine stopped and displayed a message that quickly disappeared. Since the machine was paused, the operator pressed <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">P</kbd> (Proceed : continue). The machine stopped, showing "Flatness" as the reason. The operator heard the patient on the intercom, but could not understand him, and entered the room. The patient had felt a severe burning sensation in his chest. The screen showed that he had only been given 7 rad. A few hours later, the patient showed burns on the skin in the area. Four days later the reddening of the area had a banded pattern similar to that produced in the incident the previous year, and for which they had not found the cause. The AECL began an investigation, but was unable to reproduce the event. </p><p>The hospital physicist conducted tests with film plates to see if he could recreate the incident, which involved two X-ray parameters with the turntable in field-light position. The film appeared to match the film that was left by mistake under the patient during the accident. It was found the patient was exposed to between 8,000 and 10,000 rad instead of the prescribed 86 rad. The patient died in April 1987 from complications due to radiation overdose. The relatives filed a lawsuit that ended with an out-of-court settlement.<sup id="cite_ref-Raj_3-6" class="reference"><a href="#cite_note-Raj-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Root_causes">Root causes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=11" title="Edit section: Root causes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A commission attributed the primary cause to generally poor software design and development practices, rather than singling out specific coding errors. In particular, the software was designed so that it was realistically impossible to test it in a rigorous, <a href="/wiki/Test_automation" title="Test automation">automated</a> way.<sup class="reference nowrap"><span title="Page: Safeware, 48">: Safeware, [48] </span></sup><sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="The cited source doesn't make any claim about automated testing (April 2021)">additional citation(s) needed</span></a></i>]</sup> </p><p>Researchers who investigated the accidents found several contributing causes. These included the following institutional causes: </p> <ul><li>AECL did not have the software code independently <a href="/wiki/Code_review" title="Code review">reviewed</a> and chose to rely on in-house code, including the operating system.</li> <li>AECL did not consider the design of the software during its assessment of how the machine might produce the desired results and what failure modes existed, focusing purely on hardware and asserting that the software was free of bugs.</li> <li>Machine operators were reassured by AECL personnel that overdoses were impossible, leading them to dismiss the Therac-25 as the potential cause of many incidents.<sup id="cite_ref-baase_2-2" class="reference"><a href="#cite_note-baase-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 428">: <a rel="nofollow" class="external text" href="https://archive.org/details/giftoffiresocial0000baas_r4k3/page/428/mode/2up">428</a> </span></sup></li> <li>AECL had never tested the Therac-25 with the combination of software and hardware until it was assembled at the hospital.</li></ul> <p>The researchers also found several <a href="/wiki/Engineering" title="Engineering">engineering</a> issues: </p> <ul><li>Several error messages merely displayed the word "MALFUNCTION" followed by a number from 1 to 64. The user manual did not explain or even address the error codes, nor give any indication that these errors could pose a threat to patient safety.</li> <li>The system distinguished between errors that halted the machine, requiring a restart, and errors which merely paused the machine (which allowed operators to continue with the same settings using a keypress). However, some errors which endangered the patient merely paused the machine, and the frequent occurrence of minor errors caused operators to become accustomed to habitually unpausing the machine. <ul><li>One failure occurred when a particular sequence of keystrokes was entered on the <a href="/wiki/VT100" title="VT100">VT100</a> terminal that controlled the <a href="/wiki/PDP-11" title="PDP-11">PDP-11</a> computer: If the operator were to press "X" to (erroneously) select 25 MeV photon mode, then use "cursor up" to edit the input to "E" to (correctly) select 25 MeV Electron mode, then "Enter", all within eight seconds of the first keypress and well within the capability of an experienced user of the machine, the edit would not be processed and an overdose could be administered. These edits were not noticed as it would take 8 seconds for startup, so it would go with the default setup.<sup id="cite_ref-Safeware_6-5" class="reference"><a href="#cite_note-Safeware-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup></li></ul></li> <li>The design did not have any hardware <a href="/wiki/Interlock_(engineering)" title="Interlock (engineering)">interlocks</a> to prevent the electron-beam from operating in its high-energy mode without the target in place.</li> <li>The engineer had <a href="/wiki/Code_reuse" title="Code reuse">reused</a> software from the Therac-6 and Therac-20, which used hardware interlocks that masked their software defects. Those hardware safeties had no way of reporting that they had been triggered, so preexisting errors were overlooked.</li> <li>The hardware provided no way for the software to verify that sensors were working correctly. The table-position system was the first implicated in Therac-25's failures; the manufacturer revised it with redundant switches to cross-check their operation.</li> <li>The software set a <a href="/wiki/Flag_(programming)" title="Flag (programming)">flag variable</a> by incrementing it, rather than by setting it to a fixed non-zero value. Occasionally an <a href="/wiki/Integer_overflow" title="Integer overflow">arithmetic overflow</a> occurred, causing the flag to return to zero and the software to bypass safety checks.</li></ul> <p><a href="/wiki/Nancy_Leveson" title="Nancy Leveson">Leveson</a> notes that a lesson to be drawn from the incident is to not assume that reused software is safe:<sup id="cite_ref-Leveson_2017_9-0" class="reference"><a href="#cite_note-Leveson_2017-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> "A naive assumption is often made that reusing software or using commercial off-the-shelf software will increase safety because the software will have been exercised extensively. Reusing software modules does not guarantee safety in the new system to which they are transferred ..."<sup id="cite_ref-Safeware_6-6" class="reference"><a href="#cite_note-Safeware-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> In response to incidents like those associated with Therac-25, the <a href="/wiki/IEC_62304" title="IEC 62304">IEC 62304</a> standard was created, which introduces development life cycle standards for medical device software and specific guidance on using <a href="/wiki/Software_of_unknown_pedigree" title="Software of unknown pedigree">software of unknown pedigree</a>.<sup id="cite_ref-mddi_10-0" class="reference"><a href="#cite_note-mddi-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=12" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/1962_Mexico_City_radiation_accident" title="1962 Mexico City radiation accident">1962 Mexico City radiation accident</a></li> <li><a href="/wiki/1990_Clinic_of_Zaragoza_radiotherapy_accident" class="mw-redirect" title="1990 Clinic of Zaragoza radiotherapy accident">1990 Clinic of Zaragoza radiotherapy accident</a></li> <li><a href="/wiki/Ciudad_Ju%C3%A1rez_cobalt-60_contamination_incident" title="Ciudad Juárez cobalt-60 contamination incident">Ciudad Juárez cobalt-60 contamination incident</a></li> <li><a href="/wiki/Computer_ethics" title="Computer ethics">Computer ethics</a></li> <li><a href="/wiki/Goi%C3%A2nia_accident" title="Goiânia accident">Goiânia accident</a></li> <li><a href="/wiki/High_integrity_software" title="High integrity software">High integrity software</a></li> <li><a href="/wiki/IEC_62304" title="IEC 62304">IEC 62304</a></li> <li><a href="/wiki/Ionizing_radiation" title="Ionizing radiation">Ionizing radiation</a></li> <li><a href="/wiki/List_of_civilian_radiation_accidents" title="List of civilian radiation accidents">List of civilian radiation accidents</a></li> <li><a href="/wiki/List_of_orphan_source_incidents" title="List of orphan source incidents">List of orphan source incidents</a></li> <li><a href="/wiki/Nuclear_and_radiation_accidents_and_incidents" title="Nuclear and radiation accidents and incidents">Nuclear and radiation accidents and incidents</a></li> <li><a href="/wiki/Radiation_protection" title="Radiation protection">Radiation protection</a></li> <li><a href="/wiki/Radioactive_scrap_metal" title="Radioactive scrap metal">Radioactive scrap metal</a></li> <li><a href="/wiki/Samut_Prakan_radiation_accident" title="Samut Prakan radiation accident">Samut Prakan radiation accident</a></li> <li><a href="/wiki/List_of_software_bugs#Medical" title="List of software bugs">List of software bugs</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=13" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFLeveson" class="citation web cs1">Leveson, Nancy. <a rel="nofollow" class="external text" href="http://sunnyday.mit.edu/papers/therac.pdf">"Medical Devices: The Therac-25"</a> <span class="cs1-format">(PDF)</span>. <i>sunnyday.mit.edu</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20000819003929/http://sunnyday.mit.edu/papers/therac.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on 2000-08-19.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=sunnyday.mit.edu&rft.atitle=Medical+Devices%3A+The+Therac-25&rft.aulast=Leveson&rft.aufirst=Nancy&rft_id=http%3A%2F%2Fsunnyday.mit.edu%2Fpapers%2Ftherac.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> <li id="cite_note-baase-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-baase_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-baase_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-baase_2-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFBaase2012" class="citation book cs1">Baase, Sara (5 August 2012). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/giftoffiresocial0000baas_r4k3/page/425/mode/2up">"8.2 Case Study: The Therac-25"</a></span>. <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/giftoffiresocial0000baas_r4k3"><i>A Gift of Fire: Social, Legal, and Ethical Issues for Computing Technology</i></a></span> <span class="cs1-format">(application/ld+json)</span> (4th ed.). <a href="/wiki/Prentice_Hall" title="Prentice Hall">Pearson Prentice Hall</a>. pp. <span class="nowrap">425–</span>430. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0132492676" title="Special:BookSources/978-0132492676"><bdi>978-0132492676</bdi></a>. <a href="/wiki/LCCN_(identifier)" class="mw-redirect" title="LCCN (identifier)">LCCN</a> <a rel="nofollow" class="external text" href="https://lccn.loc.gov/2012020988">2012020988</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/840390999">840390999</a>. <a href="/wiki/OL_(identifier)" class="mw-redirect" title="OL (identifier)">OL</a> <a rel="nofollow" class="external text" href="https://openlibrary.org/books/OL25355635M">25355635M</a> – via <a href="/wiki/Internet_Archive" title="Internet Archive">Internet Archive</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=8.2+Case+Study%3A+The+Therac%26%2345%3B25&rft.btitle=A+Gift+of+Fire%3A+Social%2C+Legal%2C+and+Ethical+Issues+for+Computing+Technology&rft.pages=%3Cspan+class%3D%22nowrap%22%3E425-%3C%2Fspan%3E430&rft.edition=4th&rft.pub=Pearson+Prentice+Hall&rft.date=2012-08-05&rft_id=info%3Aoclcnum%2F840390999&rft_id=info%3Alccn%2F2012020988&rft_id=https%3A%2F%2Fopenlibrary.org%2Fbooks%2FOL25355635M%23id-name%3DOL&rft.isbn=978-0132492676&rft.aulast=Baase&rft.aufirst=Sara&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fgiftoffiresocial0000baas_r4k3%2Fpage%2F425%2Fmode%2F2up&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> <li id="cite_note-Raj-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-Raj_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Raj_3-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Raj_3-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Raj_3-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Raj_3-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-Raj_3-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-Raj_3-6"><sup><i><b>g</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFLevesonTurner1993" class="citation journal cs1"><a href="/wiki/Nancy_G._Leveson" class="mw-redirect" title="Nancy G. Leveson">Leveson, Nancy G.</a>; Turner, Clark S. (1 July 1993). <a rel="nofollow" class="external text" href="https://escholarship.org/uc/item/5dr206s3">"An Investigation of the Therac-25 Accidents"</a>. <i><a href="/wiki/Computer_(magazine)" title="Computer (magazine)">Computer</a></i>. <b>26</b> (7). <a href="/wiki/IEEE_Computer_Society" title="IEEE Computer Society">IEEE Computer Society</a>: <span class="nowrap">18–</span>41. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FMC.1993.274940">10.1109/MC.1993.274940</a>. <a href="/wiki/EISSN_(identifier)" class="mw-redirect" title="EISSN (identifier)">eISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1558-0814">1558-0814</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0018-9162">0018-9162</a>. <a href="/wiki/LCCN_(identifier)" class="mw-redirect" title="LCCN (identifier)">LCCN</a> <a rel="nofollow" class="external text" href="https://lccn.loc.gov/74648480">74648480</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/2240099">2240099</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:9691171">9691171</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Computer&rft.atitle=An+Investigation+of+the+Therac-25+Accidents&rft.volume=26&rft.issue=7&rft.pages=%3Cspan+class%3D%22nowrap%22%3E18-%3C%2Fspan%3E41&rft.date=1993-07-01&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A9691171%23id-name%3DS2CID&rft.eissn=1558-0814&rft_id=info%3Adoi%2F10.1109%2FMC.1993.274940&rft_id=info%3Aoclcnum%2F2240099&rft.issn=0018-9162&rft_id=info%3Alccn%2F74648480&rft.aulast=Leveson&rft.aufirst=Nancy+G.&rft.au=Turner%2C+Clark+S.&rft_id=https%3A%2F%2Fescholarship.org%2Fuc%2Fitem%2F5dr206s3&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> <li id="cite_note-ComputerMagazine-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-ComputerMagazine_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ComputerMagazine_4-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFLeveson1993" class="citation web cs1">Leveson, Nancy G. (1 July 1993). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20041128024227/http://www.cs.umd.edu/class/spring2003/cmsc838p/Misc/therac.pdf">"An Investigation of the Therac-25 Accidents"</a> <span class="cs1-format">(PDF)</span>. Archived from <a rel="nofollow" class="external text" href="http://www.cs.umd.edu/class/spring2003/cmsc838p/Misc/therac.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 28 November 2004<span class="reference-accessdate">. Retrieved <span class="nowrap">20 May</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=An+Investigation+of+the+Therac-25+Accidents&rft.date=1993-07-01&rft.aulast=Leveson&rft.aufirst=Nancy+G.&rft_id=http%3A%2F%2Fwww.cs.umd.edu%2Fclass%2Fspring2003%2Fcmsc838p%2FMisc%2Ftherac.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> <li id="cite_note-Barbara-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-Barbara_5-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFRose1994" class="citation web cs1">Rose, Barbara Wade (1 June 1994). <a rel="nofollow" class="external text" href="http://ccnr.org/fatal_dose.html">"Fatal Dose. Radiation Deaths linked to AECL Computer Errors"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">25 May</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Fatal+Dose.+Radiation+Deaths+linked+to+AECL+Computer+Errors&rft.date=1994-06-01&rft.aulast=Rose&rft.aufirst=Barbara+Wade&rft_id=http%3A%2F%2Fccnr.org%2Ffatal_dose.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> <li id="cite_note-Safeware-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-Safeware_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Safeware_6-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Safeware_6-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Safeware_6-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Safeware_6-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-Safeware_6-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-Safeware_6-6"><sup><i><b>g</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFLeveson1995" class="citation book cs1"><a href="/wiki/Nancy_G._Leveson" class="mw-redirect" title="Nancy G. Leveson">Leveson, Nancy G.</a> (17 April 1995). <a rel="nofollow" class="external text" href="https://www.cs.ucf.edu/~dcm/Teaching/COP4600-Fall2010/Literature/Therac25-Leveson.pdf">"Appendix A: Medical Devices: The Therac-25"</a> <span class="cs1-format">(PDF)</span>. <i>Safeware: System Safety and Computers</i> (1st ed.). <a href="/wiki/Addison-Wesley" title="Addison-Wesley">Addison-Wesley</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0201119725" title="Special:BookSources/978-0201119725"><bdi>978-0201119725</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/841117551">841117551</a>. <a href="/wiki/OL_(identifier)" class="mw-redirect" title="OL (identifier)">OL</a> <a rel="nofollow" class="external text" href="https://openlibrary.org/books/OL7406745M">7406745M</a> – via <a href="/wiki/University_of_Central_Florida" title="University of Central Florida">University of Central Florida</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Appendix+A%3A+Medical+Devices%3A+The+Therac-25&rft.btitle=Safeware%3A+System+Safety+and+Computers&rft.edition=1st&rft.pub=Addison-Wesley&rft.date=1995-04-17&rft_id=info%3Aoclcnum%2F841117551&rft_id=https%3A%2F%2Fopenlibrary.org%2Fbooks%2FOL7406745M%23id-name%3DOL&rft.isbn=978-0201119725&rft.aulast=Leveson&rft.aufirst=Nancy+G.&rft_id=https%3A%2F%2Fwww.cs.ucf.edu%2F~dcm%2FTeaching%2FCOP4600-Fall2010%2FLiterature%2FTherac25-Leveson.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> <li id="cite_note-Phasers_On_Stun_pp11-16-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-Phasers_On_Stun_pp11-16_7-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFCasey1998" class="citation book cs1">Casey, Steven (1 January 1998). <i>Set Phasers on Stun: And Other True Tales of Design, Technology, and Human Error</i> (2nd ed.). Aegean Publishing Company. pp. <span class="nowrap">11–</span>16. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0963617880" title="Special:BookSources/978-0963617880"><bdi>978-0963617880</bdi></a>. <a href="/wiki/LCCN_(identifier)" class="mw-redirect" title="LCCN (identifier)">LCCN</a> <a rel="nofollow" class="external text" href="https://lccn.loc.gov/97077875">97077875</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/476275373">476275373</a>. <a href="/wiki/OL_(identifier)" class="mw-redirect" title="OL (identifier)">OL</a> <a rel="nofollow" class="external text" href="https://openlibrary.org/books/OL712024M">712024M</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Set+Phasers+on+Stun%3A+And+Other+True+Tales+of+Design%2C+Technology%2C+and+Human+Error&rft.pages=%3Cspan+class%3D%22nowrap%22%3E11-%3C%2Fspan%3E16&rft.edition=2nd&rft.pub=Aegean+Publishing+Company&rft.date=1998-01-01&rft_id=info%3Aoclcnum%2F476275373&rft_id=info%3Alccn%2F97077875&rft_id=https%3A%2F%2Fopenlibrary.org%2Fbooks%2FOL712024M%23id-name%3DOL&rft.isbn=978-0963617880&rft.aulast=Casey&rft.aufirst=Steven&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> <li id="cite_note-Rose_1994-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-Rose_1994_8-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFRose1994" class="citation magazine cs1">Rose, Barbara Wade (1 June 1994). <a rel="nofollow" class="external text" href="http://www.ccnr.org/fatal_dose.html">"Fatal Dose - Radiation Deaths linked to AECL Computer Errors"</a>. <i><a href="/wiki/Saturday_Night_(magazine)" title="Saturday Night (magazine)">Saturday Night</a></i>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0036-4975">0036-4975</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/222180972">222180972</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20211124020747/http://www.ccnr.org/fatal_dose.html">Archived</a> from the original on 24 November 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">27 December</span> 2021</span> – via <a href="/wiki/Anti-nuclear_movement_in_Canada#Canadian_Coalition_for_Nuclear_Responsibility" title="Anti-nuclear movement in Canada">Canadian Coalition for Nuclear Responsibility (CCNR)</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Saturday+Night&rft.atitle=Fatal+Dose+%26%2345%3B+Radiation+Deaths+linked+to+AECL+Computer+Errors&rft.date=1994-06-01&rft_id=info%3Aoclcnum%2F222180972&rft.issn=0036-4975&rft.aulast=Rose&rft.aufirst=Barbara+Wade&rft_id=http%3A%2F%2Fwww.ccnr.org%2Ffatal_dose.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> <li id="cite_note-Leveson_2017-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-Leveson_2017_9-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFLeveson2017" class="citation journal cs1"><a href="/wiki/Nancy_G._Leveson" class="mw-redirect" title="Nancy G. Leveson">Leveson, Nancy G.</a> (1 November 2017). <a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FMC.2017.4041349">"The Therac-25: 30 Years Later"</a>. <i><a href="/wiki/Computer_(magazine)" title="Computer (magazine)">Computer</a></i>. <b>50</b> (11). <a href="/wiki/IEEE_Computer_Society" title="IEEE Computer Society">IEEE Computer Society</a>: <span class="nowrap">8–</span>11. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FMC.2017.4041349">10.1109/MC.2017.4041349</a></span>. <a href="/wiki/EISSN_(identifier)" class="mw-redirect" title="EISSN (identifier)">eISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1558-0814">1558-0814</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0018-9162">0018-9162</a>. <a href="/wiki/LCCN_(identifier)" class="mw-redirect" title="LCCN (identifier)">LCCN</a> <a rel="nofollow" class="external text" href="https://lccn.loc.gov/74648480">74648480</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/2240099">2240099</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Computer&rft.atitle=The+Therac-25%3A+30+Years+Later&rft.volume=50&rft.issue=11&rft.pages=%3Cspan+class%3D%22nowrap%22%3E8-%3C%2Fspan%3E11&rft.date=2017-11-01&rft.eissn=1558-0814&rft_id=info%3Adoi%2F10.1109%2FMC.2017.4041349&rft_id=info%3Aoclcnum%2F2240099&rft_id=info%3Alccn%2F74648480&rft.issn=0018-9162&rft.aulast=Leveson&rft.aufirst=Nancy+G.&rft_id=https%3A%2F%2Fdoi.org%2F10.1109%252FMC.2017.4041349&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> <li id="cite_note-mddi-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-mddi_10-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFHall2010" class="citation journal cs1">Hall, Ken (1 June 2010). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20161112064520/http://www.mddionline.com/article/developing-medical-device-software-iec-62304">"Developing Medical Device Software to IEC 62304"</a>. <i><a href="/wiki/MD%26DI" title="MD&DI">MD&DI</a></i>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0194-844X">0194-844X</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/647577709">647577709</a>. Archived from <a rel="nofollow" class="external text" href="http://www.mddionline.com/article/developing-medical-device-software-iec-62304">the original</a> on 12 November 2016<span class="reference-accessdate">. Retrieved <span class="nowrap">24 December</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=MD%26DI&rft.atitle=Developing+Medical+Device+Software+to+IEC+62304&rft.date=2010-06-01&rft_id=info%3Aoclcnum%2F647577709&rft.issn=0194-844X&rft.aulast=Hall&rft.aufirst=Ken&rft_id=http%3A%2F%2Fwww.mddionline.com%2Farticle%2Fdeveloping-medical-device-software-iec-62304&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Therac-25&action=edit&section=14" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFGallagher" class="citation book cs1">Gallagher, Troy. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20071212183729/http://neptune.netcomp.monash.edu.au/cpe9001/assets/readings/www_uguelph_ca_~tgallagh_~tgallagh.html"><i>THERAC-25: Computerized Radiation Therapy</i></a>. Archived from <a rel="nofollow" class="external text" href="http://neptune.netcomp.monash.edu.au/cpe9001/assets/readings/www_uguelph_ca_~tgallagh_~tgallagh.html">the original</a> on 2007-12-12.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=THERAC-25%3A+Computerized+Radiation+Therapy&rft.aulast=Gallagher&rft.aufirst=Troy&rft_id=http%3A%2F%2Fneptune.netcomp.monash.edu.au%2Fcpe9001%2Fassets%2Freadings%2Fwww_uguelph_ca_~tgallagh_~tgallagh.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATherac-25" class="Z3988"></span> (short summary of the Therac-25 Accidents)</li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt 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class="navbox-group" style="width:1%"><a href="/wiki/Nuclear_fuel" title="Nuclear fuel">Fuel</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Tritium" title="Tritium">Tritium</a></li> <li><a href="/wiki/Deuterium" title="Deuterium">Deuterium</a></li> <li><a href="/wiki/Helium-3" title="Helium-3">Helium-3</a></li> <li><a href="/wiki/Fertile_material" title="Fertile material">Fertile material</a></li> <li><a href="/wiki/Fissile_material" title="Fissile material">Fissile material</a></li> <li><a href="/wiki/Isotope_separation" title="Isotope separation">Isotope separation</a></li> <li><a href="/wiki/Nuclear_material" title="Nuclear material">Nuclear material</a> <ul><li><a href="/wiki/Uranium" title="Uranium">Uranium</a> <ul><li><a href="/wiki/Enriched_uranium" title="Enriched uranium">enriched</a></li> <li><a href="/wiki/Depleted_uranium" title="Depleted uranium">depleted</a></li></ul></li> <li><a href="/wiki/Plutonium" title="Plutonium">Plutonium</a></li> <li><a href="/wiki/Thorium" title="Thorium">Thorium</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Neutron" title="Neutron">Neutron</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Neutron_activation" title="Neutron activation">Activation</a></li> <li><a href="/wiki/Neutron_capture" title="Neutron capture">Capture</a></li> <li><a href="/wiki/Neutron_poison" title="Neutron poison">Poison</a></li> <li><a href="/wiki/Neutron_cross_section" title="Neutron cross section">Cross section</a></li> <li><a href="/wiki/Neutron_generator" title="Neutron generator">Generator</a></li> <li><a href="/wiki/Neutron_radiation" title="Neutron radiation">Radiation</a></li> <li><a href="/wiki/Neutron_reflector" title="Neutron reflector">Reflector</a></li> <li><a href="/wiki/Neutron_temperature" title="Neutron temperature">Temperature</a></li> <li><a href="/wiki/Thermal_neutron" class="mw-redirect" title="Thermal neutron">Thermal</a></li> <li><a href="/wiki/Fast_neutron" class="mw-redirect" title="Fast neutron">Fast</a></li> <li><a href="/wiki/Neutron#Fusion_neutrons" title="Neutron">Fusion</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Nuclear_power" title="Nuclear power">Power</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Nuclear_power_by_country" title="Nuclear power by country">by country</a></li> <li><a href="/wiki/Nuclear_power_plant" title="Nuclear power plant">Power plant</a></li> <li><a href="/wiki/Economics_of_nuclear_power_plants" title="Economics of nuclear power plants">Economics</a></li> <li><a href="/wiki/Nuclear_and_radiation_accidents_and_incidents" title="Nuclear and radiation accidents and incidents">Accidents and incidents</a></li> <li><a href="/wiki/Nuclear_energy_policy" title="Nuclear energy policy">Policy</a></li> <li><a href="/wiki/Fusion_power" title="Fusion power">Fusion</a></li> <li><a href="/wiki/Radioisotope_thermoelectric_generator" title="Radioisotope thermoelectric generator">Radioisotope thermoelectric (RTG)</a> <ul><li><a href="/wiki/Multi-mission_radioisotope_thermoelectric_generator" title="Multi-mission radioisotope thermoelectric generator">MMRTG</a></li></ul></li> <li><a href="/wiki/Nuclear_propulsion" title="Nuclear propulsion">Propulsion</a> <ul><li><a href="/wiki/Nuclear_thermal_rocket" title="Nuclear thermal rocket">rocket</a></li></ul></li> <li><a href="/wiki/Nuclear_safety_and_security" title="Nuclear safety and security">Safety and security</a> <ul><li><a href="/wiki/Nuclear_meltdown" title="Nuclear meltdown">Nuclear meltdown</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Nuclear_medicine" title="Nuclear medicine">Medicine</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0;background:none;"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:4.0em;font-weight:normal;"><a href="/wiki/Medical_imaging" title="Medical imaging">Imaging</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Autoradiograph" title="Autoradiograph">Autoradiograph</a></li> <li><a href="/wiki/RadBall" title="RadBall">RadBall</a></li> <li><a href="/wiki/Scintigraphy" title="Scintigraphy">Scintigraphy</a></li> <li><a href="/wiki/Single-photon_emission_computed_tomography" title="Single-photon emission computed tomography">Single-photon emission (SPECT)</a></li> <li><a href="/wiki/Positron_emission_tomography" title="Positron emission tomography">Positron-emission tomography (PET)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:4.0em;font-weight:normal;"><a href="/wiki/Radiation_therapy" title="Radiation therapy">Therapy</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0;background:none;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Fast_neutron_therapy" title="Fast neutron therapy">Fast-neutron</a></li> <li><a href="/wiki/Neutron_capture_therapy_of_cancer" title="Neutron capture therapy of cancer">Neutron capture therapy of cancer</a></li> <li><a href="/wiki/Targeted_alpha-particle_therapy" title="Targeted alpha-particle therapy">Targeted alpha-particle</a></li> <li><a href="/wiki/Proton_therapy" title="Proton therapy">Proton-beam</a></li> <li><a href="/wiki/Tomotherapy" title="Tomotherapy">Tomotherapy</a></li> <li><a href="/wiki/Brachytherapy" title="Brachytherapy">Brachytherapy</a></li> <li><a href="/wiki/Radiosurgery" title="Radiosurgery">Radiosurgery</a></li> <li><a href="/wiki/Radiopharmacology" title="Radiopharmacology">Radiopharmacology</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Irradiation" title="Irradiation">Processing</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0;background:none;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Atomic_gardening" title="Atomic gardening">Atomic gardening</a></li> <li><a href="/wiki/Electron-beam_processing" title="Electron-beam processing">Electron-beam processing</a></li> <li><a href="/wiki/Food_irradiation" title="Food irradiation">Food irradiation</a></li> <li><a href="/wiki/Gemstone_irradiation" title="Gemstone irradiation">Gemstone irradiation</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Nuclear_weapon" title="Nuclear weapon">Weapons</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0;background:none;"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:4.0em;font-weight:normal;">Topics</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Nuclear_arms_race" title="Nuclear arms race">Arms race</a></li> <li><a href="/wiki/Nuclear_weapons_delivery" title="Nuclear weapons delivery">Delivery</a></li> <li><a href="/wiki/Nuclear_weapon_design" title="Nuclear weapon design">Design</a></li> <li><a href="/wiki/Nuclear_disarmament" title="Nuclear disarmament">Disarmament</a></li> <li><a href="/wiki/Nuclear_ethics" title="Nuclear ethics">Ethics</a></li> <li><a href="/wiki/Nuclear_explosion" title="Nuclear explosion">Explosion</a> <ul><li><a href="/wiki/Effects_of_nuclear_explosions" title="Effects of nuclear explosions">effects</a></li></ul></li> <li><a href="/wiki/History_of_nuclear_weapons" title="History of nuclear weapons">History</a></li> <li><a href="/wiki/Nuclear_proliferation" title="Nuclear proliferation">Proliferation</a></li> <li><a href="/wiki/Nuclear_weapons_testing" title="Nuclear weapons testing">Testing</a> <ul><li><a href="/wiki/High-altitude_nuclear_explosion" title="High-altitude nuclear explosion">high-altitude</a></li> <li><a href="/wiki/Underground_nuclear_weapons_testing" title="Underground nuclear weapons testing">underground</a></li></ul></li> <li><a href="/wiki/Nuclear_warfare" title="Nuclear warfare">Warfare</a></li> <li><a href="/wiki/Nuclear_weapon_yield" title="Nuclear weapon yield">Yield</a> <ul><li><a href="/wiki/TNT_equivalent" title="TNT equivalent">TNTe</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:4.0em;font-weight:normal;">Lists</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/List_of_states_with_nuclear_weapons" title="List of states with nuclear weapons">States with nuclear weapons</a></li> <li><a href="/wiki/Historical_nuclear_weapons_stockpiles_and_nuclear_tests_by_country" title="Historical nuclear weapons stockpiles and nuclear tests by country">Historical stockpiles and tests</a> <ul><li><a href="/wiki/List_of_nuclear_weapons_tests" title="List of nuclear weapons tests">Tests</a></li> <li><a href="/wiki/List_of_nuclear_weapons_tests_of_the_United_States" class="mw-redirect" title="List of nuclear weapons tests of the United States">Tests in the United States</a></li></ul></li> <li><a href="/wiki/List_of_weapons_of_mass_destruction_treaties" title="List of weapons of mass destruction treaties">WMD treaties</a></li> <li><a href="/wiki/Nuclear-weapon-free_zone" title="Nuclear-weapon-free zone">Weapon-free zones</a></li> <li><a href="/wiki/List_of_nuclear_weapons" title="List of nuclear weapons">Weapons</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Radioactive_waste" title="Radioactive waste">Waste</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0;background:none;"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:4.0em;font-weight:normal;">Products</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Actinide" title="Actinide">Actinide</a> <ul><li><a href="/wiki/Reprocessed_uranium" title="Reprocessed uranium">Reprocessed uranium</a></li> <li><a href="/wiki/Reactor-grade_plutonium" title="Reactor-grade plutonium">Reactor-grade plutonium</a></li> <li><a href="/wiki/Minor_actinide" title="Minor actinide">Minor actinide</a></li></ul></li> <li><a href="/wiki/Activation_product" title="Activation product">Activation</a></li> <li><a href="/wiki/Nuclear_fission_product" title="Nuclear fission product">Fission</a> <ul><li><a href="/wiki/Long-lived_fission_product" title="Long-lived fission product">LLFP</a></li></ul></li> <li><a href="/wiki/Actinide_chemistry" title="Actinide chemistry">Actinide chemistry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:4.0em;font-weight:normal;">Disposal</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Nuclear_fuel_cycle" title="Nuclear fuel cycle">Fuel cycle</a></li> <li><a href="/wiki/High-level_waste" title="High-level waste">High-level (HLW)</a></li> <li><a href="/wiki/Low-level_waste" title="Low-level waste">Low-level (LLW)</a></li> <li><a href="/wiki/Nuclear_decommissioning" title="Nuclear decommissioning">Nuclear decommissioning</a></li> <li><a href="/wiki/Deep_geological_repository" title="Deep geological repository">Repository</a></li> <li><a href="/wiki/Nuclear_reprocessing" title="Nuclear reprocessing">Reprocessing</a></li> <li><a href="/wiki/Spent_nuclear_fuel" title="Spent nuclear fuel">Spent fuel</a> <ul><li><a href="/wiki/Spent_fuel_pool" title="Spent fuel pool">pool</a></li> <li><a href="/wiki/Dry_cask_storage" title="Dry cask storage">cask</a></li></ul></li> <li><a href="/wiki/Nuclear_transmutation" title="Nuclear transmutation">Transmutation</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Debate</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Nuclear_power_debate" title="Nuclear power debate">Nuclear power</a></li> <li><a href="/wiki/Nuclear_weapons_debate" title="Nuclear weapons debate">Nuclear weapons</a></li> <li><a href="/wiki/Blue_Ribbon_Commission_on_America%27s_Nuclear_Future" title="Blue Ribbon Commission on America's Nuclear Future">Blue Ribbon Commission on America's Nuclear Future</a></li> <li><a href="/wiki/Anti-nuclear_movement" title="Anti-nuclear movement">Anti-nuclear movement</a></li> <li><a href="/wiki/Uranium_mining_debate" title="Uranium mining debate">Uranium mining</a></li> <li><a href="/wiki/Nuclear_power_phase-out" title="Nuclear power phase-out">Nuclear power phase-out</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible expanded navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Nuclear_reactors476" style="font-size:114%;margin:0 4em"><a href="/wiki/Nuclear_reactor" title="Nuclear reactor">Nuclear reactors</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible mw-collapsed navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Fission834" style="font-size:114%;margin:0 4em"><span style="font-size: 85%;"><a href="/wiki/Nuclear_reactor#Fission" title="Nuclear reactor">Fission</a></span></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div><div style="float: left;"><b><a href="/wiki/Neutron_moderator" title="Neutron moderator">Moderator</a></b></div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Light-water_reactor" title="Light-water reactor">Light water</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;background:none;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Aqueous_homogeneous_reactor" title="Aqueous homogeneous reactor">Aqueous homogeneous</a></li> <li><a href="/wiki/Boiling_water_reactor" title="Boiling water reactor">Boiling</a> <ul><li><a href="/wiki/GE_BWR" title="GE BWR">BWR</a></li> <li><a href="/wiki/Advanced_boiling_water_reactor" title="Advanced boiling water reactor">ABWR</a></li> <li><a href="/wiki/Economic_Simplified_Boiling_Water_Reactor" title="Economic Simplified Boiling Water Reactor">ESBWR</a></li> <li><a href="/wiki/Kerena_boiling_water_reactor" class="mw-redirect" title="Kerena boiling water reactor">Kerena</a></li></ul></li> <li><a href="/wiki/Natural_nuclear_fission_reactor" title="Natural nuclear fission reactor">Natural fission</a></li> <li><a href="/wiki/Pressurized_water_reactor" title="Pressurized water reactor">Pressurized</a> <ul><li><a href="/wiki/AP1000" title="AP1000">AP1000</a></li> <li><a href="/wiki/APR-1400" title="APR-1400">APR-1400</a></li> <li><a href="/wiki/APR%2B" class="mw-redirect" title="APR+">APR+</a></li> <li><a href="/wiki/APWR" class="mw-redirect" title="APWR">APWR</a></li> <li><a href="/wiki/ATMEA1" class="mw-redirect" title="ATMEA1">ATMEA1</a></li> <li><a href="/wiki/CAP1400" title="CAP1400">CAP1400</a></li> <li><a href="/wiki/CPR-1000" title="CPR-1000">CPR-1000</a></li> <li><a href="/wiki/EPR_(nuclear_reactor)" title="EPR (nuclear reactor)">EPR</a></li> <li><a href="/wiki/Hualong_One" title="Hualong One">HPR-1000</a> <ul><li><a href="/wiki/ACPR1000" class="mw-redirect" title="ACPR1000">ACPR1000</a></li> <li><a href="/wiki/ACP1000" class="mw-redirect" title="ACP1000">ACP1000</a></li></ul></li> <li><a href="/wiki/VVER" title="VVER">VVER</a></li> <li><a href="/wiki/RITM-200" title="RITM-200">RITM-200</a> <ul><li><a href="/wiki/KLT-40_reactor" title="KLT-40 reactor">KLT-40</a></li> <li><a href="/wiki/OK-150_reactor" title="OK-150 reactor">OK-150/OK-900</a></li> <li><a href="/wiki/OK-650_reactor" title="OK-650 reactor">OK-650</a></li></ul></li> <li><a href="/wiki/KN-3_reactor" title="KN-3 reactor">KN-3</a></li> <li><a href="/wiki/VM_reactor" title="VM reactor">VM</a></li> <li><a href="/wiki/IPWR-900" title="IPWR-900">IPWR-900</a></li> <li>many others</li></ul></li> <li><a href="/wiki/Supercritical_water_reactor" title="Supercritical water reactor">Supercritical (SCWR)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Heavy-water_reactor" class="mw-redirect" title="Heavy-water reactor">Heavy water</a><br /><span style="font-size: 85%;"><span class="nobold">by <a href="/wiki/Nuclear_reactor_coolant" title="Nuclear reactor coolant">coolant</a></span></span></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;background:none;;background:whitesmoke;"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Deuterium_oxide" class="mw-redirect" title="Deuterium oxide">D<sub>2</sub>O</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Pressurized_heavy-water_reactor" title="Pressurized heavy-water reactor">Pressurized</a> <ul><li><a href="/wiki/CANDU_reactor" title="CANDU reactor">CANDU</a> <ul><li>CANDU 6</li> <li>CANDU 9</li> <li>EC6</li> <li>AFCR</li> <li><a href="/wiki/ACR-1000" class="mw-redirect" title="ACR-1000">ACR-1000</a></li></ul></li> <li><a href="/wiki/Carolinas%E2%80%93Virginia_Tube_Reactor" title="Carolinas–Virginia Tube Reactor">CVTR</a></li> <li><a href="/wiki/IPHWR" title="IPHWR">IPHWR</a> <ul><li><a href="/wiki/IPHWR-220" title="IPHWR-220">IPHWR-220</a></li> <li><a href="/wiki/IPHWR#IPHWR-540" title="IPHWR">IPHWR-540</a></li> <li><a href="/wiki/IPHWR-700" title="IPHWR-700">IPHWR-700</a></li></ul></li> <li><a href="/wiki/Nuclear_energy_in_Argentina" class="mw-redirect" title="Nuclear energy in Argentina">PHWR KWU</a></li> <li><a href="/w/index.php?title=MZFR&action=edit&redlink=1" class="new" title="MZFR (page does not exist)">MZFR</a></li> <li><a href="/wiki/%C3%85gestaverket" class="mw-redirect" title="Ågestaverket">R3</a></li> <li><a href="/wiki/R4_nuclear_reactor" title="R4 nuclear reactor">R4 Marviken</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/H2O" class="mw-redirect" title="H2O">H<sub>2</sub>O</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/w/index.php?title=HWLWR&action=edit&redlink=1" class="new" title="HWLWR (page does not exist)">HWLWR</a> <ul><li><a href="/wiki/Fugen_Nuclear_Power_Plant" title="Fugen Nuclear Power Plant">ATR</a></li> <li><a href="/wiki/Gentilly_Nuclear_Generating_Station#Gentilly-1" title="Gentilly Nuclear Generating Station">HW BLWR 250</a></li></ul></li> <li><a href="/wiki/Steam-generating_heavy_water_reactor" class="mw-redirect" title="Steam-generating heavy water reactor">Steam-generating (SGHWR)</a></li> <li><a href="/wiki/Advanced_heavy-water_reactor" title="Advanced heavy-water reactor">AHWR</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Organic_matter" title="Organic matter">Organic</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/WR-1" title="WR-1">WR-1</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Carbon_dioxide" title="Carbon dioxide">CO<sub>2</sub></a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/w/index.php?title=HWGCR&action=edit&redlink=1" class="new" title="HWGCR (page does not exist)">HWGCR</a> <ul><li><a href="/wiki/Brennilis_Nuclear_Power_Plant" title="Brennilis Nuclear Power Plant">EL-4</a></li> <li><a href="/w/index.php?title=Kernkraftwerk_Niederaichbach&action=edit&redlink=1" class="new" title="Kernkraftwerk Niederaichbach (page does not exist)">KKN</a></li> <li><a href="/wiki/KS_150" title="KS 150">KS 150</a></li> <li><a href="/wiki/Lucens_reactor" title="Lucens reactor">Lucens</a></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;"><a href="/wiki/Graphite-moderated_reactor" title="Graphite-moderated reactor">Graphite</a><br /><span style="font-size: 85%;"><span class="nobold">by <a href="/wiki/Nuclear_reactor_coolant" title="Nuclear reactor coolant">coolant</a></span></span></div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;background:none;"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;">Water</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th id="H2O22" scope="row" class="navbox-group" style="width:2.5em;font-weight:normal;"><a href="/wiki/H2O" class="mw-redirect" title="H2O">H<sub>2</sub>O</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Obninsk_Nuclear_Power_Plant" title="Obninsk Nuclear Power Plant">AM-1</a></li> <li><a href="/wiki/Beloyarsk_Nuclear_Power_Station#Early_reactors" title="Beloyarsk Nuclear Power Station">AMB-X</a></li> <li><a href="/wiki/EGP-6" title="EGP-6">EGP-6</a></li> <li><a href="/wiki/RBMK" title="RBMK">RBMK</a></li> <li><a href="/wiki/MKER" title="MKER">MKER</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Gas-cooled_reactor" title="Gas-cooled reactor">Gas</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:2.5em;font-weight:normal;"><a href="/wiki/Carbon_dioxide" title="Carbon dioxide">CO<sub>2</sub></a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/UNGG_reactor" title="UNGG reactor"><i>Uranium Naturel Graphite Gaz</i> (UNGG)</a></li> <li><a href="/wiki/Magnox" title="Magnox">Magnox</a></li> <li><a href="/wiki/Advanced_Gas-cooled_Reactor" class="mw-redirect" title="Advanced Gas-cooled Reactor">Advanced gas-cooled (AGR)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:2.5em;font-weight:normal;"><a href="/wiki/Helium" title="Helium">He</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Gas_turbine_modular_helium_reactor" title="Gas turbine modular helium reactor">GTMHR</a> <ul><li><a href="/w/index.php?title=MHR-T&action=edit&redlink=1" class="new" title="MHR-T (page does not exist)">MHR-T</a></li></ul></li> <li><a href="/wiki/UHTREX" title="UHTREX">UHTREX</a></li> <li><a href="/wiki/Very-high-temperature_reactor" class="mw-redirect" title="Very-high-temperature reactor">VHTR (HTGR)</a> <ul><li><a href="/wiki/Pebble-bed_reactor" title="Pebble-bed reactor">PBR (PBMR)</a> <ul><li><a href="/wiki/AVR_reactor" title="AVR reactor">AVR</a></li> <li><a href="/wiki/HTR-10" title="HTR-10">HTR-10</a></li> <li><a href="/wiki/HTR-PM" title="HTR-PM">HTR-PM</a></li> <li><a href="/wiki/THTR-300" title="THTR-300">THTR-300</a></li></ul></li> <li><a href="/w/index.php?title=Prismatic_block_reactor&action=edit&redlink=1" class="new" title="Prismatic block reactor (page does not exist)">PMR</a></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Molten_salt_reactor" class="mw-redirect" title="Molten salt reactor">Molten-salt</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th id="Fluorides19" scope="row" class="navbox-group" style="width:2.5em;font-weight:normal;"><a href="/wiki/FLiBe" title="FLiBe">Fluorides</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Fuji_Molten_Salt_Reactor" title="Fuji Molten Salt Reactor">Fuji MSR</a></li> <li><a href="/wiki/Liquid_fluoride_thorium_reactor" title="Liquid fluoride thorium reactor">Liquid-fluoride thorium reactor (LFTR)</a></li> <li><a href="/wiki/Molten-Salt_Reactor_Experiment" title="Molten-Salt Reactor Experiment">Molten-Salt Reactor Experiment (MSRE)</a></li> <li><a href="/wiki/Integral_Molten_Salt_Reactor" title="Integral Molten Salt Reactor">Integral Molten Salt Reactor (IMSR)</a></li> <li><a href="/wiki/TMSR-500" class="mw-redirect" title="TMSR-500">TMSR-500</a></li> <li><a href="/wiki/TMSR-LF1" title="TMSR-LF1">TMSR-LF1</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">None<br /><span class="nobold">(<a href="/wiki/Fast-neutron_reactor" title="Fast-neutron reactor">fast-neutron</a>)</span></div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;background:none;"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td colspan="2" class="navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Fast_breeder_reactor" class="mw-redirect" title="Fast breeder reactor">Breeder (FBR)</a></li> <li><a href="/wiki/Integral_fast_reactor" title="Integral fast reactor">Integral (IFR)</a></li> <li><a href="/wiki/Liquid_metal_cooled_reactor" title="Liquid metal cooled reactor">Liquid-metal-cooled (LMFR)</a> <ul><li><a href="/wiki/OK-550_reactor" title="OK-550 reactor">OK-550</a></li> <li><a href="/wiki/BM-40A_reactor" title="BM-40A reactor">BM-40A</a></li> <li><a href="/wiki/VT-1_reactor" title="VT-1 reactor">VT-1</a></li></ul></li> <li><a href="/wiki/Small,_sealed,_transportable,_autonomous_reactor" title="Small, sealed, transportable, autonomous reactor">Small sealed transportable autonomous (SSTAR)</a></li> <li><a href="/wiki/Traveling_wave_reactor" title="Traveling wave reactor">Traveling-wave (TWR)</a></li> <li><a href="/wiki/Energy_Multiplier_Module" title="Energy Multiplier Module">Energy Multiplier Module (EM2)</a></li> <li><a href="/wiki/Reduced_moderation_water_reactor" title="Reduced moderation water reactor">Reduced-moderation (RMWR)</a></li> <li><a href="/wiki/Fast_Breeder_Test_Reactor" title="Fast Breeder Test Reactor">Fast Breeder Test Reactor (FBTR)</a></li> <li><a href="/wiki/Dual_fluid_reactor" title="Dual fluid reactor">Dual fluid reactor (DFR)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Generation_IV_reactor" title="Generation IV reactor">Generation IV</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Sodium-cooled_fast_reactor" title="Sodium-cooled fast reactor">Sodium (SFR)</a> <ul><li><a href="/wiki/BN-350_reactor" title="BN-350 reactor">BN-350</a></li> <li><a href="/wiki/BN-600_reactor" title="BN-600 reactor">BN-600</a></li> <li><a href="/wiki/BN-800_reactor" title="BN-800 reactor">BN-800</a></li> <li><a href="/wiki/BN-1200_reactor" title="BN-1200 reactor">BN-1200</a></li> <li><a href="/wiki/CFR-600" title="CFR-600">CFR-600</a></li> <li><a href="/wiki/Ph%C3%A9nix" title="Phénix">Phénix</a></li> <li><a href="/wiki/Superph%C3%A9nix" title="Superphénix">Superphénix</a></li> <li><a href="/wiki/Prototype_Fast_Breeder_Reactor" title="Prototype Fast Breeder Reactor">PFBR</a></li> <li><a href="/wiki/FBR-600" title="FBR-600">FBR-600</a></li> <li><a href="/wiki/China_Experimental_Fast_Reactor" title="China Experimental Fast Reactor">CEFR</a></li> <li><a href="/wiki/Dounreay#Prototype_Fast_Reactor_(PFR)" title="Dounreay">PFR</a></li> <li><a href="/wiki/PRISM_(reactor)" title="PRISM (reactor)">PRISM</a></li></ul></li> <li><a href="/wiki/Lead-cooled_fast_reactor" title="Lead-cooled fast reactor">Lead</a> <ul><li><a href="/wiki/BREST_(reactor)" title="BREST (reactor)">BREST-300</a></li></ul></li> <li><a href="/wiki/Gas-cooled_fast_reactor" title="Gas-cooled fast reactor">Helium gas (GFR)</a></li> <li><a href="/wiki/Stable_salt_reactor" title="Stable salt reactor">Stable Salt Reactor (SSR)</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Others</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;background:none;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Organic_nuclear_reactor" title="Organic nuclear reactor">Organic nuclear reactor</a> <ul><li><a href="/wiki/Organic_Moderated_Reactor_Experiment" title="Organic Moderated Reactor Experiment">OMRE</a></li> <li><a href="/w/index.php?title=Arbus-reactor&action=edit&redlink=1" class="new" title="Arbus-reactor (page does not exist)">Arbus</a></li> <li><a href="/wiki/Piqua_Nuclear_Generating_Station" title="Piqua Nuclear Generating Station">Piqua</a></li></ul></li> <li><a href="/wiki/Aircraft_Nuclear_Propulsion" title="Aircraft Nuclear Propulsion">Aircraft Reactor Experiment</a></li></ul> </div></td></tr></tbody></table><div> </div><table class="nowraplinks mw-collapsible autocollapse navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Fusion215" style="font-size:114%;margin:0 4em"><span style="font-size: 85%;"><a href="/wiki/Nuclear_reactor#Fusion_reactors" title="Nuclear reactor">Fusion</a></span></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div>by <a href="/wiki/Thermonuclear_fusion#Confinement" class="mw-redirect" title="Thermonuclear fusion">confinement</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Magnetic_confinement_fusion" title="Magnetic confinement fusion">Magnetic</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Field-reversed_configuration" title="Field-reversed configuration">Field-reversed configuration</a></li> <li><a href="/wiki/Levitated_dipole" title="Levitated dipole">Levitated dipole</a></li> <li><a href="/wiki/Reversed_field_pinch" title="Reversed field pinch">Reversed field pinch</a></li> <li><a href="/wiki/Spheromak" title="Spheromak">Spheromak</a></li> <li><a href="/wiki/Stellarator" title="Stellarator">Stellarator</a></li> <li><a href="/wiki/Tokamak" title="Tokamak">Tokamak</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Inertial_confinement_fusion" title="Inertial confinement fusion">Inertial</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bubble_fusion" title="Bubble fusion">Bubble <span style="font-size: 85%;">(acoustic)</span></a></li> <li><a href="/wiki/Fusor" title="Fusor">Fusor</a> <ul><li><a href="/wiki/Inertial_electrostatic_confinement" title="Inertial electrostatic confinement">electrostatic</a></li></ul></li> <li><a href="/wiki/Inertial_confinement_fusion" title="Inertial confinement fusion">Laser-driven</a></li> <li><a href="/wiki/Magnetized_target_fusion" title="Magnetized target fusion">Magnetized-target</a></li> <li><a href="/wiki/Z-pinch" title="Z-pinch">Z-pinch</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Dense_plasma_focus" title="Dense plasma focus">Dense plasma focus</a></li> <li><a href="/wiki/Migma" title="Migma">Migma</a></li> <li><a href="/wiki/Muon-catalyzed_fusion" title="Muon-catalyzed fusion">Muon-catalyzed</a></li> <li><a href="/wiki/Polywell" title="Polywell">Polywell</a></li> <li><a href="/wiki/Pyroelectric_fusion" title="Pyroelectric fusion">Pyroelectric</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><b><span class="nowrap"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b5/Radioactive.svg/21px-Radioactive.svg.png" decoding="async" width="21" height="18" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b5/Radioactive.svg/32px-Radioactive.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b5/Radioactive.svg/42px-Radioactive.svg.png 2x" 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