Medical Devices The Therac

Between June and January a computer controlled radiation ther apy machine called the Therac massively overdosed six people These accidents have been described as the worst in the year history of medical accelerators A detailed accident investigation drawn from publicly available docu ments can be found in Leveson and Turner The following account is taken from this report and includes both the factors involved in the overdoses themselves and the attempts by the users manufacturers and governments to deal with them Because this accident was never o cially investigated some information on the Therac software development management and quality control procedures are not available What is included below has been gleaned from law suits and depositions government records and copies of correspondence and other material obtained from the U S Food and Drug Administration FDA which regulates these devices