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Human Factors Risk Management as a Way to Improve Medical Device Safety: A Case Study of the Therac 25 Radiation Therapy System

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Background: In a fatal incident in 1984 much discussed in the literature, a patient received 16,000 rads instead of the intended 180 rads when undergoing radiation treatment. This incident likely could have been prevented by the use of risk analysis.

Risk Analysis: Risk analysis techniques to identify use errors have received increasing attention in health care. Use errors are defined as a pattern of predictable human errors that can be attributable to inadequate or improper design. Among the most widely used of the risk analysis tools are Failure Modes and Effects Analysis (FMEA) and fault tree analysis (FTA). The Therac 25 Radiation Therapy System incidents involved a combination of technical failures (software and possibly hardware) combined with human behavior resulting in catastrophic radiation overdoses.

Summary and Conclusions: From a manufacturer's perspective, FMEAs and FTAs are valuable methods to systematically evaluate a medical device design's potential for inducing use errors. When these risk analyses are done early in the development cycle, potential faults and their resulting hazards are identifiable and much easier to mitigate with error-reducing designs. These risk management methods are excellent complements to other important user-centered design best practices.

Document Type: Research Article

Publication date: December 1, 2004

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  • Published monthly, The Joint Commission Journal on Quality and Patient Safety is a peer-reviewed publication dedicated to providing health professionals with the information they need to promote the quality and safety of health care. The Joint Commission Journal on Quality and Patient Safety invites original manuscripts on the development, adaptation, and/or implementation of innovative thinking, strategies, and practices in improving quality and safety in health care. Case studies, program or project reports, reports of new methodologies or new applications of methodologies, research studies on the effectiveness of improvement interventions, and commentaries on issues and practices are all considered.

    Also known as Joint Commission Journal on Quality Improvement and Joint Commission Journal on Quality and Safety
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