S1336
Interdisciplinary - Education in radiation oncology
ESTRO 206
2 Department of Physics, St Luke’s Radiation Oncology Network, Dublin, Ireland Purpose/Objective: Inter-observer variability in target volume and organ- at-risk (OAR) delineation remains a source of uncertainty in radiotherapy planning.This study evaluated the impact and durability of structured contouring workshops on delineation accuracy and confidence among radiation oncology trainees. Material/Methods: A prospective analysis was conducted among radiation oncology trainees who participated in two structured, site-specific contouring workshops in head and neck (H&N) and prostate tumour sites. Each participant completed contouring tasks before the workshop, immediately afterward (within one week), and three months later, using standardised imaging datasets for selected H&N and prostate cancer cases. Participant contours were compared against expert consensus contours using quantitative spatial metrics, including Surface Dice coefficients (at 1, 2, 3 mm tolerance), Average Surface Distance (ASD), and Hausdorff Distance (HD). Improvement was defined as the percentage of participants whose post-workshop performance was greater than or equal to pre- workshop values, while retention represented the percentage maintaining or exceeding post-workshop accuracy at three months. Confidence and self- perceived learning were assessed through pre- and post-workshop questionnaires. Results: Six trainees (H&N) and seven trainees (prostate) completed all contouring tasks at the time points indicated. For H&N, contour improvement from pre- to post-workshop ranged from 62–70% and 32-68% for prostate. Immediate improvement was larger in H&N, while retention favoured prostate. For H&N, key metric improvements were Surface Dice 68.3%, ASD 70.0%, HD 70.0%, with three-month retention 39.3%, 35.7%, 42.9%; most contours remained better than pre at three months (63.0–77.8%, highest for HD, 77.8%). For prostate, improvements were Surface Dice 66.7%, ASD 67.6%, HD 32.4%, with retention 68.9%, 76.7%, 86.7%; most contours remained better than pre (86.2– 89.7%, highest for HD 89.7%).On a per-participant basis, H&N improvement ranged from 48–80%, with retention between 24–53%, whereas prostate improvement ranged from 0–96%, with higher retention (64–100%). These findings suggest that prostate contouring, which typically starts at a higher baseline accuracy, maintains improvement more effectively, while H&N—being more anatomically complex—shows greater initial gains from a much lower baseline.
Conclusion: Structured contouring workshops significantly enhanced delineation accuracy and confidence among trainees. However, improvements in contouring accuracy diminished over time, indicating limited long- term retention, especially for anatomically challenging regions. These results highlight that a single workshop provides valuable but transient benefit. To sustain and consolidate proficiency, reinforcement sessions or repeated training may be necessary to ensure consistent delineation and long-term competency in radiotherapy planning. Keywords: trainee education, skills retention, workshops Bridging the gap between knowledge and practice in radiation protection during pregnancy: a cross- sectional study. Rym zanzouri 1 , Dalia Yazid 1 , Asma Falfoul 2 , Haifa Haj Abdallah 1 , Amal Chamsi 1 , Ons Bettaieb 1 , Sarra Sghaier 1 , sabrine Tbessi 1 , Samia Kanoun 1 , Nadia Bouzid 1 , Sameh Tebra 1 1 Radiation therapy, Farhat Hached Hospital, Sousse, Tunisia. 2 Medical Oncology, Fattouma Bourguiba Hospital, Monastir, Tunisia Digital Poster 3227
Purpose/Objective: Despite well-established international
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