ESTRO 2025 - Abstract Book

S3960

Radiobiology - Normal tissue radiobiology

ESTRO 2025

4326

Digital Poster Radiobiology investigation on low-intensity neutron beam using zebrafish embryo model Emília Rita Szabó 1,2 , Júlia Rita Dudás 1 , Róbert Polanek 1 , Réka Molnár 1 , Attila Ébert 1 , Előd Búzás 3 , Parvin Varmazyar 3 , András Fenyvesi 4 , Barna Bíró 4 , Zsolt Fülöp 4 , Károly Osvay 3 , Katalin Hideghéty 1,2 1 Biomedical Application Group, ELI ALPS, Szeged, Hungary. 2 Oncotherapy Department, University of Szeged, Szeged, Hungary. 3 National Laser-Initiated Transmutation Laboratory, University of Szeged, Szeged, Hungary. 4 HUN-REN, Institute for Nuclear Research, Debrecen, Hungary Purpose/Objective: The laser-based neutron sources producing fast neutrons via the deuterium-deuterium (D-D) fusion reaction have potential applications in biology and medical sciences. However, the yield of these types of neutron sources is still limited and the biological effects of the low-intensity neutron beams are not well understood. To study this problem and validate the biological endpoints, preparatory experiments with conventional radiation sources are essential. The present study aims to investigate the Relative Biological Effectiveness (RBE) of low-intensity neutron beams compared to standard photon radiation using zebrafish embryos. The study focuses on establishing robust quantitative endpoints for assessing radiation effects. Material/Methods: Zebrafish embryos at 24 hours post-fertilization (hpf) were exposed to fast neutrons and photon radiation to compare the biological effects. Fast neutron doses of 137, 298, 685, and 779 mGy were delivered using a cyclotron based d+D neutron source at ATOMKI, that produced quasi-monoenergetic neutrons in the E_n = (2.55 - 4.1) MeV range with < E_n > = 3.7 MeV average energy. Embryos were irradiated in 2 ml Eppendorf tubes positioned on a circle at the same isodose rate, with doses controlled by irradiation time. Photon doses of 1000, 2420, 5180, and 5840 mGy were administered using a medical LINAC at the University of Szeged. After irradiation, several endpoints were evaluated to analyze and compare the biological effects of the different radiation modalities. Acridine orange fluorescent staining was employed 24 hours post-irradiation to detect apoptosis, with quantification focusing on the tail region of the embryos. Developmental outcomes were observed daily via microscopy up to 7 days post irradiation. Neurofunctional changes were evaluated on days 7 and 8 using photomotor response analysis. Each experiment was performed in triplicate. Results: Developmental parameters such as hatching rate, survival, and body morphology showed no significant changes in the applied dose ranges. However, the method for quantifying apoptotic cells proved to be highly reliable, resulting in the observation of significant dose-dependent differences and allowing the determination of RBE. For the irradiation field generated by the cyclotron-based fast neutron source, an RBE value of approximately 7 was obtained, along with reduced locomotion activity. Conclusion: This study demonstrates that zebrafish embryos are a suitable model for evaluating the radiobiological effects of low-intensity neutron beams. Quantitative endpoints, particularly apoptosis detection, proved reliable. These results will help to better understand the radiobiological effects of fast neutrons and support further exploration of the potential of laser-based neutron sources for clinical applications and basic research.

Keywords: low dose, neutron, zebrafish