S1727
Physics - Dose prediction/calculation, optimisation and applications for particle therapy planning
ESTRO 2026
(see figure 1): (a) full probability distributions, (b) 10th and 95th percentile-based summary statistics, (c) probabilities of goal achievement, and (d) voxel-wise probabilistic dose distributions where for each voxel, the 10th (VWnearmin10000) and 95th (VWnearmax10000) percentile dose values across the 10,000 simulated dose distributions were computed. As a step towards consensus, semi- structured interviews with four clinicians, two from each center, based on the application of the probabilistic evaluation metrics to several patient cases were conducted. Results: The volumetric calibrated goals are V0.95Dpres,CTV=99.95% (center 1) and V0.95Dpres,CTV=99.80% (center 2) with 90% probability. The dosimetric calibrated goals are D98%,CTV =0.970Dpres (center 1) and D98%,CTV =0.968Dpres (center 2) with 90% probability.Figure 1 illustrates the four probabilistic evaluation metrics for a HNC case. Table 2 presents the interview results. Clinicians generally preferred the volumetric calibrated goals. Clinicians preferred percentile-based summaries rather than probability distributions, while valuing the option to request the probability of achieving specific clinical goals. For the clinical goals, the clinicians were primarily interested in values corresponding to 90%,95%, and 98% probabilities. Clinicians indicated that probabilistic evaluation with these metrics could replace the VWmin/max approach for clinical decision-making.
Conclusion: These findings suggest that percentile-based metrics provide a practical and clinically interpretable framework for probabilistic evaluation in IMPT, improving trade-offs in treatment planning. This work could be the basis for achieving broader consensus amongst clinicians for each treatment site. References: 1. de Jong JI, Habraken SJM, Rojo-Santiago J, Lathouwers D, Perkó Z, Breedveld S, Hoogeman MS. Probabilistic evaluation guided IMPT planning with realistic setup and range uncertainties improves the trade-off between OAR sparing and target coverage in neuro-oncological patients. Radiother Oncol. 2025 Sep 27;213:111171. doi: 10.1016/j.radonc.2025.111171. Epub ahead of print. PMID: 41022254. Keywords: probabilistic evaluation metrics, IMPT
Mini-Oral 2314
Quantification of Tissue Parameter Estimation Uncertainties for Monte Carlo–Based Carbon Ion Dose Calculation Shutong Yu 1,2 , Yan Li 3,2 , Weiguang Li 3,2 , Chao Yang 2 , Cheng Chang 2 , Yan Chen 4 , Chong Xu 5 , Mingqing Wang 6 , Kai-Wen Li 2 , Li-Sheng Geng 7,3 , Yibao Zhang 1
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