S2895
RTT - RTT education, training, and advanced practice
ESTRO 2026
surrogate structure (MatchN), Body (B), Mediastinum (M), fluid (F), Atelectasis or pneumonia (AP), and Bone (Columna). Figure 1 shows an automated patientspecific treatment overview (in-house developed), which contains all the daily observations done by RTTs. In case of three consecutice observations a physicist will review if replanning is waranted or toleranced can be changed. The quality of the RTT-driven trigger system, the treatment overview and the daily observations were reviewed for all 106 patients.
of the ROI and a steadier on-screen display. During sinusoidal vertical motion (7 ± 0.5 mm), the breast ROI accurately tracked motion (7.2 ± 0.1 mm), whereas the flat ROI overestimated displacement (9.7 ± 0.9 mm).
Conclusion: ROIs demonstrating accurate and stable SGRT tracking were topographically distinct from those that performed poorly. This controlled evaluation confirms that surface topography underlies variability in ROI performance, supporting the use of quantitative surface metrics as objective indicators of ROI suitability. Incorporating these metrics into clinical workflows may facilitate standardised, data-driven ROI selection for more consistent SGRT performance. Keywords: SGRT, ROI, Topographic Metrics References: [1] Malone C, Ryan S, Nicholson J, Brennan S, McArdle O, Woods R, MacGairbhith A, Waldron J, Callagh C, Harwood R, McClean B, Duane F, Hanna GG. From rugged ridges to radiotherapy ROIs: Translating topographical metrics to Surface-Guided Radiation Therapy regions of Interest in radiotherapy. Radiother Oncol. 2025 Dec;213:111173. doi: 10.1016/j.radonc.2025.111173. Epub 2025 Sep 28. PMID: 41027513. Digital Poster 4967 High quality of RTT evaluation of anatomical changes triggering offline adaptations for patients with locally advanced lung cancer. Troels Lautrup Stråleklinik, AUH, Aarhus, Denmark Purpose/Objective: We evaluate the quality of the department´s systematic collection of daily registrations, made by RTTs on different structures from daily IGRT. Material/Methods: 106 patients with locally advanced lung cancer underwent radiotherapy in 2024. Daily CBCT-scans used for tumor-based setup were evaluated for anatomical changes by RTT’s before treatment. RTT’s evaluated all fractions for deviations in tumor shrinkage (TS), tumor position (T), lymphnode
Figure 1: Shows the program treatment overview and how the RTTs can see what registration has been noted for each fraction. An empty line indicates that no remake for that fraction was made. Changes made by the physicist are shown either in the blue or yellow line, depending on what was changed. Results: A total of 2899 fractions were completed. 1173 fractions (40%) had no remarks. On the remaining 1723 fractions, a total of 2709 registrations were registered. A total of 362 systematic changes triggered a physicist review. Figure 2 presents the distribution of observations and triggered reviews across the various categories. The physicist could not identify, or didn´t agree with the RTTs registrations, in only 32 (8.8%) cases. The majority of these 32 cases were due to deviations in T (15). This deviation was often caused by artifacts from respiration and the RTTs being very thorough with the evaluation. The remaining 17 cases were due to deviations in Body outline, Mediastinum, Bones, Atelectasis/Pneumonitis or MatchN
Figure 2: The blue collum shows the total number of registration made by RTTs for each of the eight categories. The purple collum indicate the number of IGRT reviews sent to a physicist for a closer inspection.
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