ESTRO 2024 - Abstract Book

S4590

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

ESTR0 2024

calibration of IMPT and VMAT plans for head-and-neck cancer [2]. However, the probability of achieving 95% of the D pres in that volume varied significantly between patients, highlighting its sensitivity to interpatient variation induced by the VWmin evaluation method. Consequently, the establishment of a uniform dosimetric goal for this patient population based solely on current clinical practice is not feasible. These findings emphasize the need for further research to define this goal, enabling, e.g., more personalized scaling, instead of adhering strictly to conventional van Herk's metrics. As a first step towards probabilistically consistent treatment planning, PCE-derived patient-specific scaling factors may be applied in the clinical TPS. The impact of this on OAR dose is modest in the clinically robust patients analyzed here, but is expected to be bigger in non-robust cases in which the trade-offs between robust CTV and OAR dose are steeper.

Keywords: IMPT, treatment planning, probabilistic evaluation

References:

1. Korevaar, E. W., Habraken, S. J., Scandurra, D., Kierkels, R. G., Unipan, M., Eenink, M. G., ... & Langendijk, J. A. (2019). Practical robustness evaluation in radiotherapy–A photon and proton-proof alternative to PTV-based plan evaluation. Radiotherapy and Oncology, 141, 267-274. 2. Rojo-Santiago, J., Korevaar, E., Perkó, Z., Both, S., Habraken, S. J., & Hoogeman, M. S. (2023). PTV-based VMAT vs. robust IMPT for Head-and-Neck Cancer: A probabilistic uncertainty analysis of clinical plan evaluation with the Dutch model-based selection. Radiotherapy and Oncology, 109729.

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Digital Poster

EQD2 correction is necessary for a correct dose accumulation in reirradiation of rectal cancer

Heidi S. Rønde 1 , Jesper F. Kallehauge 1 , Christina G. Truelsen 1,2 , Karen-Lise G. Spindler 2,3 , Laurids Ø. Poulsen 4 , Birgitte M. Havelund 5 , Lene H. Iversen 6 , Bodil G. Pedersen 7 , Camilla J.S. Kronborg 1,3 1 Aarhus University Hospital, Danish Centre for Particle Therapy, Aarhus, Denmark. 2 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus, Denmark. 3 Aarhus University, Department of Clinical Medicine, Aarhus, Denmark. 4 Aalborg University Hospital, Department of Oncology, Aalborg, Denmark. 5 Vejle Hospital, University Hospital of Southern Denmark, Department of Oncology, Vejle, Denmark. 6 Aarhus University Hospital, Department of Surgery, Aarhus, Denmark. 7 Aarhus University Hospital, Department of Radiology, Aarhus, Denmark

Purpose/Objective:

In reirradiation, it is important to do correct dose summation for a meaningful radiobiological evaluation of the accumulated doses to organs at risk (OAR). Historically physical dose summations have been used, but with new software solutions it is possible to perform voxel-by-voxel fractionation corrected doses to avoid both unintended