Safety in MR-enhanced daily adaptive SBRT Radiotherapy using a conventional C-arm linear accelerator: An FMEA approach.

Background And Purpose: MR-guided adaptive Radiotherapy has the potential to compensate for interfractional changes in patient anatomy. Modern hybrid devices, which combine MR and linear accelerator technologies, have been clinically implemented but their costs may prevent broad adoption. To accelerate the adoption of MR-guided adaptive radiotherapy, we developed a workflow for MR-enhanced daily adaptive Radiotherapy on a C-arm linac using a dedicated MR simulator and a patient transfer shuttle system. A failure mode and effects analysis (FMEA) was performed to identify possible risks in this newly developed workflow.

Materials And Methods: A workflow for MR-enhanced daily adaptive SBRT (MEDAS) on a Varian Truebeam linac was developed using a stand-alone 1.5T MR-simulator and patient transfer using a shuttle system. The different process steps were conceptualized in a multidisciplinary team and an FMEA of the different process steps was performed as well as measures for mitigation of possible risks were discussed.

Results: The FMEA identified 23 failure modes across eight process steps, with the majority occurring during base plan preparation and adaptive planning. Seventeen (74%) failure modes were classified as low risk, while six (26%) were assessed as medium risk. No high-risk failure modes were identified. Risk mitigation measures, including workflow automation and checklist enhancements, successfully reduced all failure modes to low risk while not introducing new risks CONCLUSION: We developed a workflow for MEDAS on a conventional C-Arm linac. In this process, an FMEA was performed in a multidisciplinary team. The FMEA identified and addressed six medium-risk failure modes within the MEDAS workflow. Through further automation and adaption of existing checklists, the occurrence- and discover probability was successfully reduced, such that these failure modes are decreased to a low risk.