Thursday, October 17, 2019

Reliability and Fault Tolerance Essay Example | Topics and Well Written Essays - 2500 words

Reliability and Fault Tolerance - Essay Example Report also indicates that several patients suffered serious injuries during the accident. In fact, the Therac-25 accident has been described as the worst ever series of radiation accidents in more than three decades of accelerator medical history (Leveson 1995, p. 18). This paper seeks to present a detailed analysis of the Therac-25 radiation overdose accident in light of technologies and equipments involved, what caused the accident and its consequences. The essay will also explore measures that ought to have been taken to prevent the accident. The Therac-25 radiation overdose accident of between June 1985 and January 1987 has been described as the worst ever radiation accident in the history of medical accelerators. The accidents resulted from the radiation overdose caused by the Therac-25 therapy machine. Report indicates that at least six patients were overdosed in a span of about 2 years due to faults of the machine. Report indicates that the radiation overdose was several time s the normal therapeutic dose resulting in severe burns and death, in some cases (Leveson 1995, p. 18). The first complaint of an accident was reported on June 3, 1985, when a female patient was placed on a 10-MeV electron treatment to clavicle area. However, few minutes after turning on of the Therac-25 machine, the patient complained of extreme force of heat on the body. It is then that the patient complained of having been burned by the machine. ... Nevertheless, the company still failed to investigate whether Therac-25 burned the patients or not. Shortly afterwards, the patient developed reddening and swelling at the area treated by the machine. The pain increased to a level that shoulder began freezing as spasms continued to appear. The patient’s condition continued to worsen, clearly indicating that the patient had suffered from radiation (Nancy and Clark 1993, p.19). A second series of the accident occurred at Ontario Cancer Foundation in 1985 just a week after the first patient had been overdosed at Kennestone. Report indicates that the Therac-25 at the Hamilton clinic had been in use for about six months (Leveson, Turner and Sarin 1993). However, on July 26, 1985, a patient aged 40 years old visited the hospital for the treatment of carcinoma of the cervix. Leveson, Turner, and Sarin (1993) indicate that the Therac-25 machine shut down barely five minutes after activation. This time around, the machine indicated an â€Å"H-tilt† error message. It also displayed a â€Å"no dose† and ‘treatment pause† (Nancy and Clark 1993, p.19). Despite these warnings, the operator went ahead to press the proceed button expecting the Therac-25 machine to deliver the right does this time around. Despite this being, a normal procedure since the machine had shown such faults before the machine still failed to operate. The procedure was repeated several time, but the machine showed suspend. The operator continued with the treatment after which the patient began complaining of a burning sensation on the treatment area, which she described as an â€Å"electric tingling shock† (Leveson, Turner and Sarin 1993). Other patients were successfully treated that day without accidents. The

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