ESTRO 2023 - Abstract Book

S777

Monday 15 May 2023

ESTRO 2023

Conclusion Scintillation imaging using a transparent scintillator sheet offers a unique dosimetry method, allowing UHDR dose rate measurements of individual spots. Further work on characterizing the scintillator sheet response at different geometries will allow direct 2D monitoring of the instantaneous dose rate of UHDR proton PBS with sub-millimeter spatial resolution, all with direct spatial correlation to the target’s external anatomy. OC-0930 Silicon carbide detectors for dosimetry and monitoring of UHDR beams for FLASH radiotherapy G. Milluzzo 1 , S. Capaccioli 2,3 , D. Del Sarto 4 , F. Di Martino 5,4 , M.C. D'Oca 6,7 , G. Felici 8 , M. Marrale 9,10 , L. Masturzo 11 , E. Medina 12 , M. Montefiori 3 , F. Paiar 13,14 , J.H. Pensavalle 11 , E. Sangregorio 15 , A. Vignati 16 , M. Camarda 17 , F. Romano 9 1 Istituto Nazionale di Fisica Nucleare, Sezione Catania, Catania, Italy; 2 Università di Pisa , Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP) Presidio S. Chiara, ed. 18 via Roma 67 , Pisa, Italy; 3 Università di Pisa, Department of Physics Largo B. Pontecorvo 3 I-57127 , Pisa, Italy; 4 Università di Pisa, Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP) Presidio S. Chiara, ed. 18 via Roma 67, Pisa, Italy; 5 Fisica Sanitaria, Azienda Ospedaliero Universitaria Pisa AOUP, ed.18 via Roma 67, Pisa, Italy; 6 National Institute of Nuclear Physics (INFN), Catania Division, Via Santa Sofia, 64, 95123 , Catania, Italy; 7 University of Palermo, Department of Physics and Chemistry "Emilio Segrè" Viale delle Scienze Edificio 18, Palermo, Italy; 8 SIT-Sordina, . , Aprilia, Italy; 9 National Institute of Nuclear Physics (INFN), Catania Division, Via Santa Sofia, 64, Catania, Italy; 10 University of Palermo, Department of Physics and Chemistry "Emilio Segrè", Viale delle Scienze Edificio 18, Palermo, Italy; 11 Azienda Ospedaliero Universitaria Pisa AOUP, Fisica Sanitaria, ed.18 via Roma 67, Pisa, Italy; 12 Università degli Studi di Torino , Physics Department via P. Giuria 1, 10125, Torino, Italy; 13 Università di Pisa, Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP) Presidio Santa Chiara ed. 18 via Roma 67 , Pisa, Italy; 14 Università di Pisa, Radiation Oncology Unit, Department of Translational Research, Pisa, Italy; 15 Università degli Studi di Catania, Dipartimento di Fisica, Via Santa Sofia 64, Catania, Italy; 16 Università degli Studi di Torino, Physics Department via P. Giuria 1, 10125, Torino, Italy; 17 SenSiC, DeliveryLab, Villigen, Switzerland Purpose or Objective A big effort is addressed on developing alternative detectors able to maintain a linear response at ultra-high dose-rate (UHDR), as ionization chambers suffer of ion recombination effects. Moreover, in the perspective of a clinical translation, QA measurements under the FLASH conditions imply the delivery of a huge amount of total dose per day, leading to significant radioprotection issues, especially if beam profiles are scanned with a single point like detector. In this framework, the use of high radiation hard silicon carbide (SiC) detectors for the beam dosimetry and online monitoring of UHDR beams has been experimentally investigated in the perspective to design and develop a 2D SiC array allowing the measurement of the transversal beam profiles on a single shot basis. Materials and Methods A collaboration involving the INFN Catania Division and the start-up ST-Lab (Catania) has been established for developing a new generation of SiC detectors of different thicknesses (0.2- 20 um thick) and areas (1-10 mm2), including a never explored configuration based on ultra-thin “free standing membranes” where the bulk substrate is removed. The response of the SiC detectors, was studied with UHDR electron beams using the SIT Sordina ElectronFLASH accelerator available at the Centro Pisano for Flash Radio Therapy (CPFR) in Pisa, Italy. The measurements were carried out placing the different types of SiC detectors in air at the position of 9 MeV build-up (13 mm water equivalent depth) and measuring the charge collected by the SiC detectors with a Keithley 6517A electrometer coupled with an external RC circuit (R=2K Ω , C=1uF) needed to avoid