Risk analysis of the Unity 1.5T MR-Linac adapt-to-shape workflow

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Workflow Analysis

Background:

• The adapt-to-shape (ATS) workflow on the Unity MR-Linac enables comprehensive replanning, including recontouring and reoptimization.
• Integrating MIM Maestro software with the Monaco treatment planning system adds complexity to the ATS workflow.

Purpose of the Study:

• To conduct a risk analysis of the adapt-to-shape (ATS) workflow on the Unity MR-Linac.
• To identify potential failure modes and assess their associated risks within the ATS workflow, particularly when using MIM Maestro and Monaco software.

Main Methods:

• Failure Modes and Effects Analysis (FMEA) was performed following Task Group 100 guidelines.
• A multidisciplinary team mapped the ATS process, identifying failure modes and scoring them by likelihood, severity, and detectability.
• Mitigation strategies were developed for the highest-risk failure modes.

Main Results:

• A total of 264 failure modes were identified within the ATS workflow.
• 82 high-ranking failure modes were found, with 62 concentrated in the contouring and planning stages.
• Contouring and planning steps present significant risks in ATS, unlike adapt-to-position (ATP) workflows.

Conclusions:

• The flexibility of ATS, while beneficial for reoptimization, introduces critical points for potential errors.
• Errors within the ATS workflow can lead to unintended negative dosimetric impacts.
• FMEA is a valuable tool for identifying and mitigating risks in complex radiotherapy workflows like ATS.