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A Comparison of Two Risk Analysis Techniques for Surface Image Guided Radiosurgery

G Kim

G Kim*, R Manger , T Pawlicki , University of California, San Diego, La Jolla, CA


MO-FG-CAMPUS-T-1 (Monday, July 13, 2015) 4:30 PM - 5:00 PM Room: Exhibit Hall

Purpose: Failure Modes and Effects Analysis (FMEA) techniques have been used to analyze surface image guided radiosurgery (SIG-RS). Hazard model, a modified FMEA approach developed by the Dutch, is applied to SIG-RS risk assessment and evaluated against the AAPM’s FMEA approach.

Methods: The SAFER approach uses a risk inventory matrix to categorize hazards (rather than probabilities). A multidisciplinary team was assembled to create the process map of SIG-RS and 91 steps and 167 failure modes were determined. Each failure mode was categorized for frequency (weekly, monthly, quarterly, yearly and less than once a year) and severity (negligible, minor, moderate, major and catastrophic) according to the SAFER procedures. All failure modes are placed in the matrix of arbitrary risk score matrix: very high, high, low, and very low. The top 14 high risk failure modes from the result of FMEA and SAFER analysis were compared.

Results: 167 failure modes categorized in the risk inventory matrix with 1 very high, 13 high, 66 low and 87 very low. Comparison of top 14 high risk failure modes between two techniques shows 9 common failure modes and 5 isolated failure modes. Two failure modes (FM: 58, 145) with the highest risk priority number (both RPN=288) in FMEA are also ranked as high risk in SAFER analysis. However one failure mode (FM: 154) with very high risk score in SAFER is not recognized by FMEA analysis due to its low “lack of detectability” score.

Conclusion: FMEA is a well-established technique for prospective risk analysis. SAFER is a practical alternative that is easy to implement with a reliable category structure. Also the risk inventory matrix is conceptually straightforward to obtain agreement among multidisciplinary team members but still demonstrates a full scale of criticality.

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