ESTRO 2025 - Abstract Book

S2423

Physics - Autosegmentation

ESTRO 2025

Table 1 summarizes pooled results comparing AI-detected volumes with clinical volumes across patients. The bladder is reliably detected, while the rectum shows good overlap (DSC > 0.85) but a high Hausdorff distance due to outliers. The prostate is generally well estimated but tends to be overestimated in size. SVs are poorly represented in both position and size.

The time taken for the adaptive process on ETHOS TM averaged 7.77 minutes. A learning curve was observed where large outliers (60 minutes or more) were eliminated.

Conclusion: AI accurately predicts bladder contours and shows some systematic differences in rectal contours due to fixed drawing protocols. While AI-delineated prostate contours are generally reasonable, variability exists. Seminal vesicles are poorly delineated by AI. Effective use of ETHOS TM requires well-trained staff, to facilitate a labour intensive procedure and maintain good patient throughput.

Keywords: ETHOS, Adaptive Radiotherapy, Contouring