ESTRO 2024 - Abstract Book

S3663

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

In this study, a generalizable dynamic collimator rotation strategy for non-coplanar VMAT is proposed and notable differences of the dosimetric plan quality were observed for VMAT plans with dynamic collimator rotation compared to plans with static collimator angle using an in-house optimizer.

Supported by Varian, a Siemens Healthineers Company and SNSF grant 200021_185366. Calculations were performed on UBELIX (wwww.id.unibe.ch/hpc), the high-performance cluster at the University of Bern.

Keywords: Non-coplanar VMAT, dynamic collimator rotation

2400

Digital Poster

In-silico study of VHEE treatments: pancreatic and lung cancer in conventional and FLASH regimes.

Angelica De Gregorio 1 , Daniele Carlotti 2 , Michele Fiore 2 , Gaia Franciosini 3 , Teresa Insero 2 , Valerio Maré 2 , Annalisa Muscato 4 , Sara` Ramella 2 , Alessio Sarti 3 , Angelo Schiavi 3 , Marco Schwarz 5 , Vincenzo Patera 3 1 Sapienza Università di Roma, Department of Physics, Rome, Italy. 2 Fondazione Policlinico Universitario Campus Bio-medico, Radiation Oncology, Rome, Italy. 3 Sapienza Università di Roma, Department of Scienze di Base Applicate per l'Ingegneria, Rome, Italy. 4 Sapienza Università di Roma, Scuola post-laurea in Fisica Medica, Dipartimento di Scienze e Biotecnologie medico-chirurgiche, Roma, Italy. 5 niversity of Washington & Fred Hutchinson Cancer Center, Radiation Oncology Department, Seattle, USA

Purpose/Objective:

Very High Energy Electron (VHEE) beams have recently been studied [1] for the treatment of deep-seated tumors due to their unique dose distribution properties providing a more effective sparing of critical organs after the PTV along the beam line when compared to radiotherapy (RT). The availability of VHEE in clinical facilities, which was historically limited by the complexity of beam production and delivery systems, is now being explored in light of recent advancements in electron acceleration technology. Such treatments are particularly appealing now also in view of the recent discovery of the FLASH effect [2], that can be triggered delivering the treatments at ultra high dose rates reducing toxicity in healthy tissues while maintaining the same level of effectiveness in eradicating cancer cells. As electrons can be easily produced and delivered at FLASH intensities, their exploration by means of an 'ad-hoc' Treatment Planning System (TPS) becomes particularly interesting. By means of an in-silico study, it has been possibile to compare the results expected from VHEE with the state of the art conventional irradiation (VMAT and PT plans) in terms of absorbed dose maps and DVHs evaluating the treatment potential.

Material/Methods:

In the pursuit of determining the energy and intensity of electron beams, the TPS we developed from scratch uses dose maps obtained from FRED [3] MC simulation carried out under pre-defined energy settings and entry points (fields). The optimiser minimizes a cost function, which quantifies how well a treatment plan aligns with its competing goals, by varying the fluences of each pencil beam and adjusting the dose distribution within the practical constraints of clinical implementation. This optimization process involves employing minimization Annealing algorithms that allow to take into account volumetric and dose-rate constraints. The different plans