S1954
Physics - Dose prediction/calculation, optimisation and applications for photon and electron planning
ESTRO 2026
Implementazione Clinica Della Flash Radiotherapy (CPFR@CISUP), University of Pisa, Pisa, Italy. 7 Pisa Division, National Institute of Nuclear Physics (INFN), Pisa, Italy. 8 S. I. T., Sordina Iort Technologies S. p. A., Aprilia (LT), Italy. 9 Fisica Sanitaria, Azienda Ospedaliero Universitaria Pisa AOUP, University of Pisa, Pisa, Italy. 10 "Enrico Fermi", Historical Museum of Physics and Study Research Centre (CREF), Rome, Italy. 11 Department of Radiation Oncology, Azienda Ospedaliera Universitaria Pisana, University of Pisa, Pisa, Italy. 12 Post graduate School in Medical Physics, University of Pisa, Pisa, Italy. 13 Department of Industrial Engineering, Tor Vergata University of Rome, Rome, Italy Purpose/Objective: FLASH radiotherapy is an innovative cancer treatment delivering ultra-high dose rates (UHDR > 40 Gy/s) to exploit the FLASH effect, which reduces normal tissue toxicity while preserving tumor control. Since its biological mechanisms remain unclear, ongoing research aims to better understand this phenomenon. Clinical trials play a key role in safely exploring UHDR potential where current technology already enables such delivery, e.g. low-energy irradiation of skin tumours. These trials require accurate planning for approval, dose delivery, and patient follow-up. This study presents the development of a Monte Carlo (MC)-based Treatment Planning System (TPS) specifically designed for FLASH electron radiotherapy (FLASH-eRT) in skin cancer treatment using UHDR low- energy (< 10 MeV) electron beams. Material/Methods: The FLASH-eRT TPS presented in this contribution exploits FLUKA [1] MC-based simulations to select the best beam energy and geometric beam positioning, ensuring a homogeneous dose distribution within the target, while minimizing exposure to surrounding healthy tissues. Moreover rectangular beam shaper aperture is optimized enhancing dose conformity and allowing adaptation to different target geometries. Figure 1 illustrates the implemented geometry and the simulation setup used to validate the beam model against water phantom data.
and Dmin remained within 1% deviation from the reference, whereas Dmax exceeded this threshold from 120 keV upward. For VMI energies lower than the optimal 70 - 90 keV range, deviations in all DVH parameters progressively increased, amounting to 0.5–1.0% at 60 keV and up to 1–2% at 50 keV.
Conclusion: This study demonstrates that DECT-based dose calculations are robust across a broad range of VMI energies when calibration is properly assigned. Deviations remain clinically negligible (<1%) within the 70–90 keV range, confirming the reliability of DECT for photon radiotherapy dose computation. Ongoing work aims to extend the analysis to additional anatomical sites and larger patient cohorts to assess the generalizability of these results. Keywords: Dual-Energy CT, Dose Calculation Development of a Treatment Planning System (TPS) for FLASH-RT in the skin tumor clinical trial planned at the CPFR in Pisa Laura Frassi 1 , Alberto Burattini 2,3 , Marina Carruezzo 3,4 , Andrea Cavalieri 5,6 , Mariagrazia Celentano 6,7 , Veronica De Liso 8 , Massimo Di Francesco 8 , Fabio Di Martino 9,7 , Gaia Franciosini 3,4 , Michela Marafini 10,4 , Fabiola Paiar 6,11 , Vincenzo Patera 3,4 , Jake H. Pensavalle 8,12 , Marco Pezzulli 13 , Flaminia Quattrini 1 , Angelo Schiavi 3,4 , Luana Testa 1,10 , Marco Toppi 3,4 , Giacomo Traini 4 , Arianna Vannucci 10,2 , Alessio Sarti 3,4 Poster Discussion 3831 1 Department of Physics, Sapienza University of Rome, Rome, Italy. 2 Post graduate School in Medical Physics, Sapienza University of Rome, Rome, Italy. 3 Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Rome, Italy. 4 Roma I section, National Institute for Nuclear Physics (INFN), Rome, Italy. 5 Center for Instrument Sharing of the University of Pisa (CISUP), University of Pisa, Pisa, Italy. 6 Centro Pisano Multidisciplinare Sulla Ricerca e
Figure 1: FLUKA geometrical model of the applicator, beam shaper, and water phantom used to validate the beam model against reference data. A detailed view of the tungsten slit holder is shown in the top rightThe TPS will be used for the clinical trial planned at CPFR [2], involving approximately 100 patients with head or
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