Operating procedures, risk management and challenges during implementation of adaptive and non-adaptive MR-guided radiotherapy: 1-year single-center experience

Abstract

Background Main purpose was to describe procedures and identify challenges in the implementation process of adaptive and non-adaptive MR-guided radiotherapy (MRgRT), especially new risks in workflow due to the new technique. We herein report the single center experience for the implementation of (MRgRT) and present an overview on our treatment practice. Methods Descriptive statistics were used to summarize clinical and technical characteristics of treatment and patient characteristics including sites treated between April 2019 and end of March 2020 after ethical approval. A risk analysis was performed to identify risks of the online adaptive workflow. Results A summary of the processes on the MR-Linac including workflows, quality assurance and possible pitfalls is presented. 111 patients with 124 courses were treated during the first year of MR-guided radiotherapy. The most commonly treated site was the abdomen (42% of all treatment courses). 73% of the courses were daily online adapted and a high number of treatment courses (75%) were treated with stereotactic body irradiation. Only 4/382 fractions could not be treated due to a failing online adaptive quality assurance. In the risk analysis for errors, the two risks with the highest risk priority number were both in the contouring category, making it the most critical step in the workflow. Conclusion Although challenging, establishment of MRgRT as a routinely used technique at our department was successful for all sites and daily o-ART was feasible from the first day on. However, ongoing research and reports will have to inform us on the optimal indications for MRgRT because careful patient selection is necessary as it continues to be a time-consuming treatment technique with restricted availability. After risk analysis, the most critical workflow category was the contouring process, which resembles the need of experienced staff and safety check paths.

Dosimetric benefits of adaptive radiation therapy for patients with stage III non-small cell lung cancer

“…This offers the possibility to adjust the therapy based on the biological information [ 58 ]. The disadvantages of MR-guided ART are the low availability of MR linacs [ 62 ], the required manpower that has to be present during the entire treatment [ 60 ], and the treatment duration [ 61 – 63 ].…”

Risk analysis of the Unity 1.5 T MR‐Linac adapt‐to‐position workflow

“…A secondary monitor unit check and dosimetric measurements of the plan were also performed. Specialized training was also necessary for all professionals treating on the MRL as workflow and the software used likely deviated from those that previously existed in the clinic 13–15 . Klüter et al.…”

ICRU REPORT 97: MRI-Guided Radiation Therapy Using MRI-Linear Accelerators

“…Mitigation strategies such as standardized workflow, clearly-defined protocols, and checklists to ensure protocol adherence were implemented to minimize all the high risks that were classified based on the combination of probability and severity levels to an acceptable level (Klüter et al , 2021). Contouring and electron density assignment were also reported to be the highest risk priority categories by different institutions (Garcia Schüler et al , 2021; Rippke et al , 2022). The quality of the contour directly impacts the quality of the treatment plan as shown by an example in Fig.…”