A risk assessment of automated treatment planning and recommendations for clinical deployment

Abstract

Purpose: To assess the risk of failure of a recently developed automated treatment planning tool, the radiation planning assistant (RPA), and to determine the reduction in these risks with implementation of a quality assurance (QA) program specifically designed for the RPA.

Methods: We used failure mode and effects analysis (FMEA) to assess the risk of the RPA. The steps involved in the workflow of planning a four-field box treatment of cervical cancer with the RPA were identified. Then, the potential failure modes at each step and their causes were identified and scored according to their likelihood of occurrence, severity, and likelihood of going undetected. Additionally, the impact of the components of the QA program on the detectability of the failure modes was assessed. The QA program was designed to supplement a clinic's standard QA processes and consisted of three components: (a) automatic, independent verification of the results of automated planning; (b) automatic comparison of treatment parameters to expected values; and (c) guided manual checks of the treatment plan. A risk priority number (RPN) was calculated for each potential failure mode with and without use of the QA program.

Results: In the RPA automated treatment planning workflow, we identified 68 potential failure modes with 113 causes. The average RPN was 91 without the QA program and 68 with the QA program (maximum RPNs were 504 and 315, respectively). The reduction in RPN was due to an improvement in the likelihood of detecting failures, resulting in lower detectability scores. The top-ranked failure modes included incorrect identification of the marked isocenter, inappropriate beam aperture definition, incorrect entry of the prescription into the RPA plan directive, and lack of a comprehensive plan review by the physician.

Conclusions: Using FMEA, we assessed the risks in the clinical deployment of an automated treatment planning workflow and showed that a specialized QA program for the RPA, which included automatic QA techniques, improved the detectability of failures, reducing this risk. However, some residual risks persisted, which were similar to those found in manual treatment planning, and human error remained a major cause of potential failures. Through the risk analysis process, we identified three key aspects of safe deployment of automated planning: (a) user training on potential failure modes; (b) comprehensive manual plan review by physicians and physicists; and (c) automated QA of the treatment plan.

Keywords: FMEA; automated treatment planning; external beam radiation therapy; quality assurance; risk analysis.

Figure 1

Depiction of the subprocesses and steps involved in automatically planning a four‐field box radiotherapy treatment for cervical cancer with the radiation planning assistant (RPA). Subprocesses 1 and 2 computed tomography (CT simulation and plan directive) involve many manual steps from which errors could propagate downstream. Subprocess 3 (RPA plan creation) is entirely automatic. Abbreviations: MLC, multileaf collimator; TPS, treatment planning system.

Figure 2

Histogram of the risk priority numbers (RPN) for all potential failure modes identified for automatic planning of a cervical cancer treatment using the radiation planning assistant (RPA) with (blue) and without (red) the quality assurance (QA) program.

Figure 3

Histogram of the detectability score (D) for all potential failure modes identified for automatic planning of a cervical cancer treatment using the radiation planning assistant (RPA) with (blue) and without (red) the quality assurance (QA) program.