S2866
RTT - RTT education, training, and advanced practice
ESTRO 2026
MR-Linac Treatment Times in Clinical Routine: A Multi Treatment Site Evaluation Lieke Meijers, Pim Borman, Eline de Groot-van Breugel, Louk Snoeren, Alexis Kotte, Reijer Rutgers, Roel Bouwmans, Martijn Intven, Bas Raaymakers Radiotherapy, UMC Utrecht, Utrecht, Netherlands Purpose/Objective: Magnetic Resonance-guided Radiotherapy (MRgRT) provides superior soft-tissue visualization and enables daily online adaptation. Despite these advantages, MR- Linac treatments are often perceived as excessively time-consuming, limiting patient throughput and clinical feasibility. Over recent years, workflow optimizations and growing team experience have substantially shortened MRgRT treatment durations. This study aimed to quantify the current treatment times across all treatment sites treated with MRgRT at our center. Material/Methods: Total time per fraction was defined as the interval between the start of the 3D MRI pre-scan and the end of radiation delivery, as extracted from the record- and-verify system. Fractions were grouped by treatment site and workflow type: adapt-to-position (ATP), adapt-to-shape (ATS), and ATS with minimal manual contour adaptations (ATS-Lite). Mean and median times were calculated and compared with the benchmark data reported by Westerhoff et al [1]. Results: In total, 5295 treatment fractions across 585 patients were analyzed (Figure 1 and Table 1). Median treatment times were 25.8 minutes for prostate ATS, 35.8 minutes for abdominal ATS sites (liver, pancreas, kidney and adrenal gland) and 12.2 minutes for a prostate ATP treatment. Outliers resulted mostly from treatment interruptions or technical faults. Compared to the workflow timings reported by Westerhoff et al., all workflows showed improved efficiency, particularly prostate ATS, following implementation of a deep-learning auto-contouring step.
Purpose/Objective: Adaptive Radiation Therapy (ART) enhances treatment precision by accounting for anatomical and physiological changes throughout the treatment course. While ART is known to improve clinical outcomes, its implementation is resource-intensive, requiring frequent imaging, plan adaptation, and increased clinical oversight. In contrast, non-adaptive CBCT-guided workflows use static plans but often necessitate reactive interventions that also consume significant time and departmental resources. This study aims to quantify the time-related burden of unplanned activities in non-adaptive workflows and identify disease sites that may benefit most from planned ART, particularly in the context of limited ART- capable devices in Canada. Material/Methods: A retrospective analysis was performed on 6,887 treatment fractions from 300 patients treated with CBCT-guided radiotherapy across 20 treatment techniques of various disease sites. Unplanned activities, such as repeated CBCT acquisitions, aborted sessions, additional planning CTs, and mid-course replanning, were identified through electronic medical records and imaging logs. Time burden was calculated using timestamp data from treatment management systems. The study was approved by the institutional Quality Improvement Review Committee. Results: Repeated CBCTs were required in 55% of patients, resulting in 201.9 hours of additional imaging time. Each repeated CBCT added an average of 13 minutes (range: 2–219 minutes), impacting both patient experience and departmental throughput. Bladder and gynecologic cancers exhibited the highest frequency of repeat imaging, often due to organ filling variability. Six sessions were aborted and rescheduled due to unresolved anatomical discrepancies. Fifteen patients required plan modifications, including 9 repeat planning CTs, and 3 sarcoma cases with treatment interruption of 2-6 days. Conclusion: Non-adaptive CBCT-guided workflows impose a substantial resource burden, often comparable to or exceeding that of ART. These findings support a more strategic implementation of ART, particularly for bladder, cervix, and sarcoma cancers, where anatomical variability frequently disrupts standard workflows. Prioritizing ART for these high-burden disease sites may optimize resource utilization, reduce treatment delays, and improve overall patient care within current system constraints. Keywords: Non-Adaptive, resource burden and optimization
Digital Poster Highlight 2312
Made with FlippingBook - Share PDF online