Evaluation of safety in a radiation oncology setting using failure mode and effects analysis

Abstract

Purpose: Failure mode and effects analysis (FMEA) is a widely used tool for prospectively evaluating safety and reliability. We report our experiences in applying FMEA in the setting of radiation oncology.

Methods and materials: We performed an FMEA analysis for our external beam radiation therapy service, which consisted of the following tasks: (1) create a visual map of the process, (2) identify possible failure modes; assign risk probability numbers (RPN) to each failure mode based on tabulated scores for the severity, frequency of occurrence, and detectability, each on a scale of 1 to 10; and (3) identify improvements that are both feasible and effective. The RPN scores can span a range of 1 to 1000, with higher scores indicating the relative importance of a given failure mode.

Results: Our process map consisted of 269 different nodes. We identified 127 possible failure modes with RPN scores ranging from 2 to 160. Fifteen of the top-ranked failure modes were considered for process improvements, representing RPN scores of 75 and more. These specific improvement suggestions were incorporated into our practice with a review and implementation by each department team responsible for the process.

Conclusions: The FMEA technique provides a systematic method for finding vulnerabilities in a process before they result in an error. The FMEA framework can naturally incorporate further quantification and monitoring. A general-use system for incident and near miss reporting would be useful in this regard.

Fig. 1

External beam process map exhibiting 269 process nodes. Nodes highlighted in black indicate the top 15 potential failure points as ranked by the risk probability number (RPN). The square indicates the detailed region shown in Fig. 2. Symbols denote the following: square, action; ellipse, process; diamond, decision point; and trapezoid, record.

Fig. 2

Example of a process map highlighting the production and handling of digitally reconstructed radiographs (DRR) in the radiation treatment planning process circa 2006.