S1655
Physics - Detectors, dose measurement and phantoms
ESTRO 2026
Giuseppe Peroglio Carus 5 , Maria Grazia Giri 1 , Carlo Cavedon 1 1 Medical Physics Unit, Department of Pathology and Diagnostics, Azienda Ospedaliera Universitaria Integrata, Verona, Italy. 2 Specialization School in Medical Physics, University of Padova, Padova, Italy. 3 Medical Physics Department, ASST Spedali Civili Hospital, Brescia, Italy. 4 Specialization School in Medical Physics, University of Milano, Milano, Italy. 5 Tecnologie Avanzate, T.A. Srl, Torino, Italy Purpose/Objective: In the last few years, the use of plastic scintillation detectors (PSDs) has become widespread. This study aims to characterize a new low-noise, high time- resolution PSD developed by Blue Physics (BP-PSD) on a 6 MV flattening-filter-free MRI-Linac system. The device is suitable for single-LINAC-pulse dose measurement without the need for time-consuming spectrum or Cherenkov effect corrections. Its potential applications, especially in small-field dosimetry, are explored on the hybrid system, and performance compared with various detectors. Material/Methods: The scintillator has been tested on a 0.35 T MRI-Linac (Viewray Systems). Measurements have been performed using 1D MR-compatible IBA water-tank. BP-PSD’s calibration procedure have been assessed. Percentage-Depth-Dose (PDD) for 9.96x9.96 cm2 field and Field-Output-Factors (FOFs) for small (0.83×0.83 cm2, 1.66×1.66 cm2, 2.49×2.49 cm2 and 3.32×3.32 cm2) and standard-fields (6.64×6.64 cm2, 9.96x9.96 cm2, 12.45x12.45 cm2, 16.6x16.6 cm2, 20.75x20.75 cm2 and 24×24 cm2) have been analyzed. PDD and FOFs of small fields have been evaluated against those measured with PTW Semiflex and Microdiamond detectors. Results: Two different scintillator calibration procedures have been tested: using FOFs and collimator rotation. The latter has been simulated using the multileaf collimator in two configurations, however a dose difference of 0.3% has been observed with a ionization chamber, favoring the first method. PDD shows differences between the investigated detectors within 1%, similarly happens with respect to treatment planning system (TPS) values.
Conclusion: The MFTV technique intends to reduce verification uncertainties by combining all available information and applying a new detector system. The first detector characterization experiment showed that the best obtainable time resolution with this system is non- inferior to currently used PG detector units. Improved time resolutions are expected in prompt-gamma experiments, due to the increased detector gains when compared to proton experiments. This work provides a first step in the development of a more robust and reliable treatment verification approach. References: 1. Berthold et al. (2023). Detectability of anatomical changes with Prompt-Gamma Imaging: First systematic evaluation of clinical application during prostate-cancer proton therapy. doi.org/10.1016/j.ijrobp.2023.05.0022. Martins et al. (2017). Prompt gamma spectroscopy for range control with CeBr3. doi.org/10.1515/cdbme-2017-0023 Keywords: prompt gamma-ray timing, PGI, range verification Digital Poster 2802 Performance evaluation of a new plastic scintillation detector for MRI-Linac dosimetric characterization in comparison with other commercial detectors Marina Fedon Vocaturo 1,2 , Luisa Altabella 1 , Pier Giorgio Esposito 1 , Martina Peretti 3,2 , Valeria Cardamuro 3,4 ,
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