S1702
Physics - Detectors, dose measurement and phantoms
ESTRO 2026
Conclusion: A novel detector model was successfully implemented in an MC software. The study showed that a majority of detected FN events compared to PG events, which might be attributed to the triple coincidence interactions required for PG detection versus only two required for FN detection. Overall, a substantial number of both FN- and PG events are detectable, laying the foundation for a dual-particle approach that could improve the robustness of range estimates. Keywords: Proton beam range verification, prompt gamma rays
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Time-resolved characterization of clinical and ultra-high-dose-rate electron beams using a hydrogenated amorphous silicon detector Marta Ponzecchi 1 , Keida Kankxeri 2,3 , Aisha Bashiri 4 , Elisa Gazzera 5 , Maria Vittoria Rossi 5 , Leonello Servoli 3 , Stefania Pallotta 6,1 , Marco Petasacca 4 , Umberto Deut 7,8 , Simona Giordanengo 8 , Diango M.M. Olivares 7,8 , Anna Vignati 7,8 , Domenico Caputo 9,10 , Gianpiero de Cesare 9,10 , Nicola Lovecchio 9,10 , Cinzia Talamonti 6,1 1 sezione Firenze, Istituto Nazionale di Fisica Nucleare (INFN), Firenze, Italy. 2 Fisica e Geologia, Università degli Studi di Perugia, Perugia, Italy. 3 sezione Perugia, Istituto Nazionale di Fisica Nucleare (INFN), Perugia, Italy. 4 physics department, University of Wollongong, Wollongong, Australia. 5 Fisica medica, Azienda Ospedaliero Universitaria Careggi, Firenze, Italy. 6 Dipartimento di Scienze Biomediche Sperimentali e Cliniche "Mario Serio", Università degli studi di Firenze, Firenze, Italy. 7 Fisica, Università di Torino, Torino, Italy. 8 sezione Torino, Istituto Nazionale di Fisica Nucleare (INFN), Torino, Italy. 9 Dipartimento Ingegneria dell’Informazione, Elettronica e Telecomunicazioni, Sapienza Università di Roma, Roma, Italy. 10 sezione Roma 1, Istituto Nazionale di Fisica Nucleare (INFN), Roma, Italy Purpose/Objective: The study aims to evaluate the capability of an innovative hydrogenated amorphous silicon (a-Si:H) detector for time-resolved characterization of electron beams, with particular focus on ultra-high-dose-rate (UHDRE) regimes relevant to FLASH radiotherapy. The goal is to assess the detector’s temporal response and its suitability for accurate dosimetry in clinical and research settings. Material/Methods: The a-Si:H detector is a 5x6 pin diode matrix deposited on a Kapton substrate. Each pixel has a dimension of 2x2 mm2 and an intrinsic thickness of 0.4 μm. The device was read out by a TetrAMM electrometer, featuring four channels, operating with a 10 μs
Results: The number of detected FN events per spot was greater than the number of detected PG events by a factor of 2.9–5.2. A growing number of events coinciding with rising spot energies was seen for all patients (Figure 2). Distinctly elevated event counts for the highest spot energies were discerned for the HNC patient, reaching 14820 and 76200 detected FNs and PGs, respectively. The number of PG- and FN events varied noticeably between patients, with the highest- and lowest event counts seen in the HNC and lung patients, respectively.
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