ESTRO 2023 - Abstract Book

S775

Monday 15 May 2023

ESTRO 2023

Conclusion The observed dose differences between the chambers appear to be related to inconsistencies in the determination of the kQ values. For PP ICs, MC studies account for the physical thickness of the entrance window rather than the water equivalent thickness. The additional energy loss that the wall material invokes is not negligible for the IBA PPC05 and might partially explain the low kQ values determined for this chamber and, hence, the lower dose values measured in all facilities for this chamber. Furthermore, the new kQ recommended values increase the observed dose differences between chambers. To resolve these inconsistencies and to benchmark the MC calculated values, kQ measured values by calorimetry are needed. OC-0929 Scintillation imaging for time-resolved 2D monitoring of ultra-high dose rate proton beam scanning E. Kanouta 1 , P. Bruza 2 , M. Clark 2 , J. Sunnerberg 2 , J. Harms 3 , J. Johansen 1 , P. Poulsen 1 1 Aarhus University Hospital, Danish Centre for Particle Therapy, Aarhus, Denmark; 2 Dartmouth College, Thayer School of Engineering, Hanover, NH, USA; 3 University of Alabama at Birmingham, Department of Radiation Oncology, Birmingham, AL, USA Purpose or Objective Dosimetry is essential for FLASH radiotherapy studies. It requires dosimeters capable of handling ultra-high dose rates (UHDR). For pencil beam scanning (PBS) proton beams, high spatial and temporal resolution is furthermore required to provide information about each individual spot delivery. Here we propose a novel high-speed camera-based, time-resolved 2D in vivo dosimetry, where a transparent scintillator sheet placed downstream the target in transmission proton FLASH experiments would allow direct monitoring of the dose and dose rate distribution relative to the target anatomy (Fig. 1A). In this first study we characterize the high-speed camera and transparent scintillator sheet with UHDR PBS proton beams.