Dose-dependent changes after proton and photon irradiation in a zebrafish model

Abstract

Background/Aim: The importance of hadron therapy in the cancer management is growing. We aimed to refine the biological effect detection using a vertebrate model. Materials and Methods: Embryos at 24 and 72 h postfertilization were irradiated at the entrance plateau and the mid spread-out Bragg peak of a 150 MeV proton beam and with reference photons. Radiation-induced DNA double-strand breaks (DSB) and histopathological changes of the eye, muscles and brain were evaluated; deterioration of specific organs (eye, yolk sac, body) was measured. Results: More and longer-lasting DSBs occurred in eye and muscle cells due to proton versus photon beams, albeit in different numbers. Edema, necrosis and tissue disorganization, (especially in the eye) were observed. Dose-dependent morphological deteriorations were detected at ≥10 Gy dose levels, with relative biological effectiveness between 0.99±0.07 (length) and 1.12±0.19 (eye). Conclusion: Quantitative assessment of radiation induced changes in zebrafish embryos proved to be beneficial for the radiobiological characterization of proton beams.