Date: 17 January 1987

Location: Yakima Valley Memorial Hospital, Yakima, Washington, USA

Type of event: radiotherapy accident

Description:

A defect in the computer program controlling the Therac-25 radiation therapy accelerator resulted in overexposures to patients. A male patient was overexposed (estimated dose 8000-10000 rads localized), immediately reporting pain and developing skin burns later that day. The patient, although previously suffering from terminal cancer, died in April of complications related to the overexposure.

Consequences: 1 fatality.

References:

• Leveson, Nancy, and Clark S. Turner, July 1993, "An investigation of the Therac-25 accidents," IEEE Computer, 26:18-41, on line at Computer Science at Virginia Tech [http://courses.cs.vt.edu/~cs3604/lib/Therac_25/Therac_3.html].

© 2004 by Wm. Robert Johnston.
Last modified 13 June 2004.
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