ESTRO 2025 - Abstract Book

S3263

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2025

FB and AC are dominated by respiratory motion (median HD95: 3.8 and 2.6 mm), wherein cardiac motion is blurred, while BH shows predominantly cardiac motion (3.3 mm). FB patients displayed significantly larger motion (Mann Whitney U-test p<10 -6 ) compared to AC (Fig.1). Smaller CS showed larger VR, with the largest VR for the coronary arteries in every setup (Fig.1).

The change in CI was marginal for FB, TR, and AC (median ΔCI: -0.05, -0.02, and -0.02, respectively) but larger for BH (-0.136), likely due to smaller PTVs (Fig.2). LV dose parameters are stable, but small CS dose can be severely impacted (Fig.2). Conclusion: FB showed the largest motion although the median values are low and the dose effect of this motion was limited. BH showed reduced motion but larger dose differences for targets and CS. In the future, 5-dimensional imaging data is desirable to analyse combined CRM.

Keywords: cardiorespiratory motion, STAR, substructures

References: [1] van der Pol LHG, et al. Auto-contouring of cardiac substructures for Stereotactic arrhythmia radioablation (STAR): A STOPSTORM.eu consortium study. Radiother Oncol. 2024;202:110610. [2] S. Klein, M. Staring, K. Murphy, M.A. Viergever, J.P.W. Pluim, "elastix: a toolbox for intensity based medical image registration," IEEE Transactions on Medical Imaging, vol. 29, no. 1, pp. 196 - 205, January 2010