ESTRO 2024 - Abstract Book

S3335

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Results of this work showed that in the in-line direction and under the parallel configuration, profile measurements are affected by the DV effect, which results in a systematic shift in the EPOM of the SF-3D detector by 0.5mm. Consequently, there is a direct impact on CAX measurements in the in-line direction if not accounted for. Results of this work indicate that the effect can be mitigated if the IC is positioned in the vertical orientation. In the cross-line direction and using the MD as a reference, the SF-3D EPOM is shifted by 1mm. This may lead to more accurate set ups and more stringent beam profile and output factor measurements, required for small field data acquisition and TPS model verification. Acknowledgements: PTW is acknowledged for providing detailed schematics of the corresponding detectors. This work was supported by computational time granted from the Greek Research & Technology Network (GRNET) in the National HPC facility—ARIS— under project ID pr012035.

Keywords: ion chamber, profile, MR-linac

References:

[1] De Pooter J, Billas I, De Prez L, Duane S, Kapsch RP, Karger CP, et al. Reference dosimetry in MRI-linacs: evaluation of available protocols and data to establish a Code of Practice. Phys Med Biol 2021;66

[2] O’Brien DJ, Dolan J, Pencea S, Schupp N, Sawakuchi GO. Relative dosimetry with an MR-linac: Response of ion chambers, diamond, and diode detectors for off-axis, depth dose, and output factor measurements. Med Phys 2018;45:884–97 [3] Margaroni V, Pappas EP, Episkopakis A, Pantelis E, Papagiannis P, Marinos N, et al. Dosimetry in 1.5 T MR-Linacs: Monte Carlo determination of magnetic field correction factors and investigation of the air gap effect. Med Phys 2023;50:1132–48 [4] Pojtinger S, Kapsch RP, Dohm OS, Thorwarth D. A finite element method for the determination of the relative response of ionization chambers in MR-linacs: Simulation and experimental validation up to 1.5 T. Phys Med Biol 2019;64

2426

Proffered Paper

Plastic scintillator sheets for quality assurance in electron Flash radiotherapy

Matteo Morrocchi 1,2 , Rebecca Anzalone 1 , Andrea Cavalieri 1,2 , Esther Ciarrocchi 1,2 , Damiano Del Sarto 1,2 , Fabio Di Martino 3,2 , Eleonora Ravera 1,2 , Maria Giuseppina Bisogni 1,2 1 University of Pisa, Department of Physics, Pisa, Italy. 2 INFN, Pisa Section, Pisa, Italy. 3 Pisa University Hospital, Fisica Sanitaria, Pisa, Italy

Purpose/Objective: