ESTRO 2025 - Abstract Book

S3532

Physics - Optimisation, algorithms and applications for ion beam treatment planning

ESTRO 2025

Results: Figure 2 shows the population D 99.8%,CTV histogram, patient adequate CTV-dose probabilities and the scenario D mean,Heart and 2YM-NTCP distributions. The 90 th -10 th percentile range of the population D 99.8% /D pres was well above the prescription (95%), with a D 99.8% /D pres of 97.4 (range:96.4-98.0)% on average at a 90% probability. Patient adequate CTV-dose probabilities were 99.6 (range:96.0-100)% on average. D mean heart doses were sensitive to breathing, geometrical and range errors due to the Bragg-Peak dose gradient, resulting in a median D mean dose-spread of 2.9 (95 th -5 th percentile:1.6-4.7) GyRBE and a median 2YM-NTCP-spread of 3.8 (95 th -5 th percentile:2.4-6.1)%-points.

Conclusion: Our 4DPRE method demonstrated that our clinical protocol is safe but leads to excessively robust plans. Its clinical implementation could effectively optimize CTV-OAR dose trade-offs, thus improving IMPT planning for EC patients.

Keywords: Probabilistic planning, IMPT, 4D robustness

References: [1] Rojo-Santiago, J., Korevaar, E., Perkó, Z., Both, S., Habraken, S. J., & Hoogeman, M. S. (2023). PTV-based VMAT vs.