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The Therac-25 is a computer-controlled radiation therapy machine produced by Atomic Energy of Canada Limited (AECL) in 1982 after the Therac-6 and Therac-20 units (the earlier units had been produced in partnership with Compagnie générale de radiologie (CGR) of France).
Between 1985 and 1987, a series of design flaws in AECL's Therac-25 medical accelerator caused massive overdoses of radiation [18] on 6 different occasions, resulting in five deaths. In 1987 the machine was found defective by the Food and Drug Administration (FDA) and eventually recalled by AECL despite their multiple denials that the problems ...
Therac-25 Incidents [ edit ] Yakima Valley Memorial Hospital was the site of two clinical radiotherapy incidents, wherein hospital staff used a Therac-25 machine to treat cancer patients. [ 12 ]
There are exceptions, such as the Therac-25 accidents and the 1958 Cecil Kelley criticality accident, where the absorbed doses in Gy or rad are the only useful quantities, because of the targeted nature of the exposure to the body. Radiotherapy treatments are typically prescribed in terms of the local absorbed dose, which might be 60 Gy or higher.
1985 to 1987 – The Therac-25 was a radiation therapy machine produced by Atomic Energy of Canada Limited (AECL). It is known to be responsible for six accidents between 1985 and 1987, in which patients were given massive overdoses of radiation, which were in some cases on the order of hundreds of grays. Three patients died as a result of the ...
Therac-25 used a 25 MeV electron beam to produce an X-ray for treatment. 25 MeV is 25 million electron volts (eV -- an eV is the energy needed to move one electron through a potential of one volt). Image A simulated cross section view of radiation dispersing upon entering the body [A simulated cross section view of radiation dispersing upon ...
Race conditions were among the flaws in the Therac-25 radiation therapy machine, which led to the death of at least three patients and injuries to several more. [18] Another example is the energy management system provided by GE Energy and used by Ohio-based FirstEnergy Corp (among other power facilities). A race condition existed in the alarm ...
Electron beams impinging on metal produce X-rays. The X-rays may be diagnostic, e.g., dental or limb images. Often in these X-ray tubes the metal is a spinning disk so that it doesn't melt; the disk is spun in vacuum via a magnetic motor. The X-rays may also be used to kill cancerous tissue. The Therac-25 machine is an infamous example of this.