ESTRO 2023 - Abstract Book

S1494

Digital Posters

ESTRO 2023

Conclusion Even though the inspected data are the same, there is clear evidence the two distributions are not exchangeable. This leads us to establish different action limits for each software, as shown in table 1. The disparities we observed might stem from differences between the two gamma analysis algorithms that PDA and OP use. Our work suggests that, if not well understood, applying AAPM TG 218 tools, could mislead the end user towards misinterpretation of the DQA results. For future developments, our aim is to generate known errors in order to check for the sensitivity of the two systems and reach a better understanding of the PDA algorithm. So far, the obtained PDA distributions are compacted to the upper limits of the measurement scale.

PO-1773 Characterization of new detectors for FLASH radiotherapy with ultra-high dose rates proton beams

P. Casolaro 1 , G. Dellepiane 1 , A. Gottstein 1 , I. Mateu 1 , P. Scampoli 1,2 , S. Braccini 1

1 University of Bern, Laboratory for High Energy Physics (LHEP), Bern, Switzerland; 2 University of Naples Federico II, Department of Physics "Ettore Pancini", Naples, Italy Purpose or Objective New detectors, based on miniaturized fast scintillators and optical fibers, have been developed and characterized at the University of Bern for FLASH radiotherapy. The scintillation light is driven by an optical fiber outside the irradiation room to a fast photodetector connected to a high-bandwidth digitizer. This work reports on the characterization of three detector prototypes featuring plastic, Gadolinium Aluminium Gallium Garnet (GAGG), and Yttrium-doped Barium Fluoride (Y-BaF2) scintillators under ultra-high dose rate proton beams. Materials and Methods Irradiations were carried out at the Bern medical cyclotron, which provides a high intensity 18 MeV proton beam. In addition to the radioisotopes production for nuclear medicine, this facility allows for multidisciplinary research activities thanks to a Beam Transfer Line (BTL) ending in a separate bunker with independent access. Proton dose rates of the order of 40 Gy/s and higher were measured at the detector test position. Results A linear response was been observed for the three detector prototypes under average proton dose rates typical of the FLASH regime. The proton dose was measured as a function of the irradiation time with different time resolutions from 100 ns to 100 µ s; the spatial resolution of the detectors is given by the scintillator (0.5x0.x5x2 mm ³ ). Conclusion The findings of this work prove that new detectors based on optical fibers and fast scintillators are promising for addressing several issues in FLASH radiotherapy, including Quality Assurance (QA), real-time beam monitoring, radiation protection and in-vivo dosimetry. This work also shows that a medical cyclotron can in fact produce ultra-high dose rates, needed for testing new detectors for FLASH radiotherapy. This last feature is particularly important, given the growing interest for FLASH radiotherapy and the limited availability of facilities delivering ultra-high dose rates. On the basis of these results, further developments and beam tests are planned with different particles and irradiation conditions.

PO-1774 Design and in-silico evaluation of a breast IOERT aligner to prevent OAR irradiation

J. Tarrats Rosell 1 , C. Cases 1 , M. Garcia-Causapié 2 , G. Trias 2 , G. Oses 1 , A. Herreros 1 , M. Molla 1

1 Hospital Clínic de Barcelona, Servei d'Oncologia Radioteràpica (ICHMO), Barcelona, Spain; 2 Hospital Clínic de Barcelona, Direcció d'Infraestructures i Enginyeria Biomèdica, Barcelona, Spain

Purpose or Objective