The patient through visual and audio monitors located within the Order to prevent unnecessary radiation exposure to individuals The Therac-25 is enclosed in a radiation treatment room in
Machine, in the event that a beam is incorrectly produced This produces another possible hazard of the Mechanism is used to control the beam concentration because noīeam is expected. When the machine is in field light position, no Position, which uses a light to help position patientsĬorrectly. The turntable also includes a third mode, the field-light High output rate will occur this is a significant hazard of aĭual-mode machine, because it is possible that not all theĭevices will be lined up properly and a high output could occur. If the beam flattener is not in position, a dangerously Only one level ofĮnergy (25-MeV) is available in photon mode (O'Brien, 1985, p.ġ01). Used to produce a consistent treatment area. In photon mode, a much greaterĮlectron-beam current is needed because a "beam flattener" is Various levels of energy are available (from 5 to 25-MeV) When the machine is in electron mode, magnets on the turntable By positioning elementsĬorrectly, a turntable controls which mode the machine will use. Two magnets to fold the electrons 180 degrees and 270 degreesīefore reaching their target. Structure (Leveson and Turner, 1993, p.19). It requires much less space because it has a unique design Like the Therac-20, the Therac-25 is a dual-mode machine, but Of work needed to move an electron through a potential of 1 voltĬompanies ended their partnership, AECL developed the Therac-25. That produced X-rays only and the Therac-20 is a 20-MeV X-ray The Therac-6 is a six million electron volt (MeV) accelerator Two linacs before the Therac-25: the Therac-6 and the Therac-20. To reach deeper tissue, X-ray photons are needed (Grolier,ĪECL combined forces with a French company, CGR, and created Shallow tissue is treated with electrons, but That is fatal to tumor cells but causes relatively minor damage Normal tissues to radiation exposure, a treatment plan can beĭeveloped that permits the absorption of an amount of radiation Since malignant tissues are more sensitive than To beams of particles, or radiation, in doses designed to kill a Linacs are used to treat cancer patients. Introduction of an electric field, producing beams of particles The charged particle are accelerated by the A linear accelerator ("linac") is a particle accelerator,Ī device that increases the energy of electrically chargedĪtomic particles. The Therac-25 is a medical linear accelerator manufactured byĪECL. Have an answer to the question: Whose job is it to ask, andĪnswer, medical equipment safety questions? Lastly, I will lookĪt the government's reactions and explore what has been done to
7 DAYS TO DIE CONSOLE COMMANDS DENIED SOFTWARE
Will examine the Therac-25's software bugs. I will study various propositions, regarding theĪccidents, made by Atomic Energy of Canada Limited (AECL), theĬompany who designed and produces the Therac-25. Next, I willĮxamine the accident history, and explore the causes behind theĪccidents. In this paper I willįirst explain what a medical linear accelerator is and thenĭescribe the birthing process of the Therac-25. So, whose job is it to ask, and answer,īetween June 1995 and January 1987, six patients were seriously injured or killed by unsafe administration of radiation from the Therac-25 medical linear accelerator. Is safe and that the people who designed it and manipulate itĪre properly qualified. That you would assume that the machine delivering the radiation I would guess that you might ask a few of these questions, but