ESTRO 2025 - Abstract Book

S2625

Physics - Detectors, dose measurement and phantoms

ESTRO 2025

Results: 2 institutes (INST1 and INST2) performed the tests on EPID IVD system. Among the EPID implementations, 23/32 (72%) measurements achieved >85% of pixels gamma passing rate (GPR) (showed in Figure1(a)). The smallest field (2x2) exhibited the least accurate results for INST1. INST2 showed better agreement, apart for largest field. The overall EPID IVD %DD (mean±1SD) was quite similar: (-1.22±1.84)% and (1.25±3.71)% for INST1 and INST2, respectively. The overall tests comparison of all 4 institutes for secondary independent calculation among the RadCalc modules and TPS is showed in Figure1(b). 58/80 (73%) passing >85% GPR. Small size fields (2cmx2cm and 5cmx5cm) showed the lower accuracy among all combinations, except for INST2. The overall %DD (mean±1SD) was (0.38±2.14)%.

Conclusion: Specific implementations of the same software modules showed an acceptable homogeneity of performance, even if small field size remains challenging. This highlights the importance of rigorous commissioning procedures and benchmarking to ensure optimal results across different setups. The results obtained with different IVD software in a multicenter context were consistent and showed an acceptable homogeneity.

Keywords: QA, secondary dose calculations, EPID “In vivo”

References: [1] Marco Esposito, Riccardo Baldoni, Evy Bossuyt, Sara Bresciani, Catharine H Clark, Matthew Jones, Stephen Kry, Joseph Perry, Jeroen van de Kamer, Dirk Verellen, Nuria Jornet, A commissioning protocol for portal imaging-based radiotherapy in vivo dosimetry systems, Physics and Imaging in Radiation Oncology, Volume 32, 2024, https://doi.org/10.1016/j.phro.2024.100666.