A quantitative irradiation microscopy platform for in situ observation of living cells with subcellular resolution under radiation conditions.

To address the critical need for investigating proton radiation effects on living cells in space environments and deciphering biological mechanisms underlying low-dose cumulative radiation effects, this study developed a microbeam irradiation microscopy platform. The system integrates a 10 MeV proton accelerator with a vertical microbeam line design. An ultrafast single-proton counting and radiation synchronisation control module-employing proton-photon-electron conversion and high-speed photoelectric circuitry achieve deterministic irradiation control with an end-to-end operational delay of 273.5 ns. Coupled with wide-field and confocal fluorescence microscopy, the platform enables real-time in situ observation during quantitative cellular irradiation, facilitating mechanistic studies of radiation-induced damage patterns and signal transduction in low-dose scenarios. Experimental validation using human embryonic kidney 293T cells demonstrated successful simulation of space radiation environments: dose-dependent DNA double-strand breaks (visualised via γ-H2AX foci) and radiation-induced bystander effects triggering damage propagation. These results establish the platform as an indispensable tool for space radiation health risk assessment while providing foundational insights into microscale energy deposition dynamics for proton therapy research.