S1703
Physics - Detectors, dose measurement and phantoms
ESTRO 2026
sampling period and without external bias. Measurements were conducted with two different machines: the medical linac at the University Hospital in Florence and the research linac at the INFN facility in Turin. Initially, the detector was tested using the 8 MeV conventional and the 9 MeV high-dose rate electron (HDRE) beams, delivered by the medical machine. Finally, the device was evaluated under a 10 MeV UHDRE beam irradiation, using the research linac. All acquisitions were performed at the isocenter, at the depth of maximum dose in solid water slabs, setting a field size of 10x10 cm2 and by varying the dose rate of the beams. HDRE measurements were performed with a 40x40 cm2 field size due to the clinical purpose of the beam. Furthermore, acquisitions under the UHDRE regime were also conducted near the source, with an SSD of 53 cm, to test the detector also at higher doses. Thanks to the different setups, measurements were performed by varying the dose-per-pulse (DPP) from mGy (conventional and HDRE beams) to Gy levels (UHDRE beam). Results: The detector provided sufficient time resolution to observe the periodical structure of the beams (Fig.1) and resolve single pulses under all dose-rate conditions (Fig 2). Pulse amplitude and collected charge increased by three orders of magnitude: from tens of nA and a few pC, under the conventional regime, to tens of μA and a few nC, under the UHDRE regime. Stable and reproducible waveforms were obtained in both clinical and UHDRE setups, confirming consistent response and absence of signal saturation.
Conclusion: The a-Si:H detector demonstrated excellent temporal response, linearity, and stability, confirming its capability for precise time-resolved characterization of electron beams in both clinical and UHDRE regimes. These results highlight its potential as a versatile instrument for investigating beam structure and supporting FLASH-oriented radiotherapy research. Keywords: a-Si:H, FLASH therapy, pin detector
Made with FlippingBook - Share PDF online