ESTRO 2025 - Abstract Book

S2481

Physics - Autosegmentation

ESTRO 2025

Results: In daily practice, DL-based auto-contouring for thoraco-abdominal paediatric RT is applied by 8/12 participants (median experience: 11–15 years; range: 3–25 years). All participants manually delineated at least one case. The median number of contoured organs per session was significantly higher with DL-based revision compared to manual delineation: 24 (range: 7–32) vs. 10 (range: 6–24), respectively. The average time required for full-case delineation was reduced by 61%, from 69 minutes in manual sessions to 27 minutes with DL-based revision (Figure 1A). Accuracy (DSC) improved across all OARs when DL contours were available, increasing from 0.91±0.09 (manual) to 0.97±0.03 (DL-based revision), with the pancreas showing the largest gain (0.67±0.29 to 0.92±0.04) (Figure 1B). IOV decreased by 43% overall, improving from 0.05 (manual) to 0.03 (DL-based revision). Conclusion: DL-based auto-contouring with manual revision significantly reduces delineation time, enhances accuracy, and improves inter-observer consistency in paediatric CT-based OAR delineation.