S1654
Physics - Detectors, dose measurement and phantoms
ESTRO 2026
to the commercial reference model. Conclusion:
(MFTV) approach which will address these limitations. Multiple complementary prompt-gamma features will get combined, fully exploiting the available information. A new detector system was designed, and a first characterization step performed. Material/Methods: The new detector system was designed to increase throughput, by incorporating multiple smaller, uncollimated and (un)segmented detectors (Figure 1a).A first characterization experiment has been performed using the pencil beam scanning beamline of a ProteusPLUS proton therapy system (IBA). Time resolutions were determined for one segmented and one unsegmented detector based on scattered proton coincidences, for proton energies from 75 – 225 MeV. Coincidence protons were measured in a reference detector with known time resolution on one side and the novel detector array on the other side (Figure 1b). Only coincidence events with full energy deposition in both detectors were included in the analysis. Obtained time resolutions were compared to time resolutions of a standard 2"×2" CeBr3 prompt-gamma (PG) detector [2], being approximately 663 ps for 75 MeV and 259 ps for 225 MeV (Figure 2b).
This study demonstrated that by controlling the infill density of PLA+, soft-tissue attenuation characteristics can be finely adjusted, while Bone filament effectively reproduces cortical bone properties. The MRCP based dual-material head phantom achieved both structural and radiological fidelity to human anatomy, confirming its potential as a standardized, patient-equivalent model for dose verification, imaging system calibration, and radiotherapy QA research. These findings establish a practical methodology for developing anatomically accurate, tissue-equivalent 3D printed phantoms that bridge computational models and experimental validation. References: [1] Kim, Chan Hyeong, et al. "ICRP publication 145: adult mesh-type reference computational phantoms." Annals of the ICRP 49.3 (2020): 13-201.[2] Mutic, Sasa, et al. "Quality assurance for computed ‑ tomography simulators and the computed ‑ tomography ‑ simulation process: report of the AAPM Radiation Therapy Committee Task Group No. 66." Medical physics 30.10 (2003): 2762-2792 Keywords: 3D Printed Head Phantom, MRCP, Electron Density Mini-Oral 2719 Introducing Multi-Feature Treatment Verification for proton therapy Thyrza Z. Jagt 1,2 , Franziska Wecker 1 , Katja E. Römer 3 , Andreas Wolf 4 , Sara Müller 1,2 , Konstantin Urban 1,2 , Aaron Kieslich 1,2 , Toni Kögler 1,2 1 Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, Hemholtz-Zentrum Dresden-Rossendorf, OncoRay – National Center for Radiation Research in Oncology, Dresden, Germany. 2 Institute of Radiooncology – OncoRay, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany. 3 Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany. 4 Research and Development, Rapiscan Systems GmbH, Wuppertal, Germany Purpose/Objective: In online-adaptive proton therapy, range verification is of great importance. Current techniques using emitted secondary prompt gamma-rays generally focus on single features, i.e. their origin, timing or energy. However, high instantaneous detector loads and short detection times substantially limit event throughput. This leads to reduced statistics and, consequently, increased uncertainty, particularly when assessing individual pencil-beam spots [1]. In this work, we introduce a novel Multi-Feature Treatment Verification
Results: Each detector unit includes either a 2×2 segmented or an unsegmented (full) CeBr3 crystal, attached to a Silicon Photomultiplier and a dedicated front-end- electronics board (Figure 1a). To increase gain stability, a water-cooling system is connected to each detector. A detector array was constructed from two full-crystal detector units and two segmented-crystal units.The best obtained time resolutions were found for 225 MeV protons, being (181 ± 37) ps for the segmented crystals and (192 ± 16) ps for the full crystals (Figure 2b).
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