Treatment time and learning curve analysis of 1.5 T MR-Linac workflows led by radiation oncologists or therapists

J. M. Westerhoff*, F. J. Raaijmakers, L. A. Daamen, E. N. de Groot-van Breugel, L. T.C. Meijers, J. R.N. van der Voort van Zyp, J. J.C. Verhoeff, S. Mook, H. M. Verkooijen, M. P.W. Intven

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Background and purpose: This study assessed the treatment time of online adaptive (i.e. Adapt-to-Shape, ATS) and virtual couch shift (i.e. Adapt-to-Position, ATP) magnetic resonance guided radiotherapy (MRgRT) on a 1.5 Tesla MR-Linac. Additionally, the transition from a radiation oncologists (RO)-led to a radiation therapist (RTT)-led workflow, and the presence of a learning curve were assessed. Materials and methods: This study was conducted utilizing the prospective Multi-OutcoMe EvaluatioN of radiation Therapy Using the MR-Linac study (MOMENTUM, NCT04075305). Mean (±standard deviation) online adaptation time and total treatment time were collected from MR-Linac log files. Learning and proficiency phases were defined using a cumulative sum (CUSUM) analysis. Independent T-tests were performed. A p-value < 0.01 was considered statistically significant. Results: In total, 4942 fractions of 645 patients were included. Mean total treatment time was 39 (±7), 15 (±2), 34 (±8), 41 (±11), and 40 (±7) minutes for ATS-treated prostate cancer, ATP-treated prostate cancer, ATS-treated pelvic lymph node metstasis (LNM), ATS-treated abdominal LNM and ATS-treated rectal cancer, respectively. Mean online adaptation time of RO-led and RTT-led treatment was 28 (±6) and 25 (±6) minutes (p < 0.001) for ATS-treated prostate cancer. No significant differences in the remaining subgroups were found. In subgroups with a learning curve, mean online adaptation time of learning and proficiency phase were 30 (±6) and 26 (±5) minutes (p < 0.001) for ATS-treated prostate cancer, 27 (±8) and 19 (±7) minutes for pelvic LNM (p < 0.001), and 29 (±7) and 25 (±7) minutes (p < 0.001) for rectal cancer, respectively. Conclusion: The transition from RO-led to RTT-led workflows did not significantly increase total treatment time. The online adaptation time reduced after a learning curve for ATS-treated prostate cancer, pelvic LNM and rectal cancer. Keywords; MRgRT, MR-Linac, time, prostate cancer, oligolymphnode metastasis, rectal cancer.

Original languageEnglish
Article number100901
JournalClinical and translational radiation oncology
Volume51
DOIs
Publication statusPublished - Mar 2025

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