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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. The software set a flag variable by incrementing it, rather than by setting it to a fixed non-zero value.
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 ...
Such incidents would not have been an issue in a single-use machine and unlike previous models, the Therac-25 relied on software rather than hardware safety interlocks. What happened was the operator using a keypad would select a particular mode. The machine would then start a programmed cycle and move plates into position.
However, mistakes do occasionally occur; for example, the radiation therapy machine Therac-25 was responsible for at least six accidents between 1985 and 1987, where patients were given up to one hundred times the intended dose; two people were killed directly by the radiation overdoses.
MINC-11 – Laboratory system based on 11/03 or 11/23; [25] when based on the 11/23, it was sold as a 'MINC-23', but many MINC-11 machines were field-upgraded with the 11/23 processor. Early versions of the MINC-specific software package would not run on the 11/23 processor because of subtle changes in the instruction set; MINC 1.2 is ...
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 ...
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.
The most notable is the Therac-25 incident. [3] Here, the software for a large radiotherapy device was poorly designed and tested. In use, several interconnected problems led to several devices giving doses of radiation several thousands of times higher than intended, which resulted in the death of three patients and several more being ...