Microscopic Imaging of Alpha Particle Trajectory and Its Application for Radionuclide Distribution Measurement in Cell.

Imaging and analyzing alpha-particle trajectories are crucial for studying alpha-particle distributions in high-energy physics experiments, such as radioisotope imaging and neutron energy spectrum measurements. This study introduces a novel method that combines an electron-multiplying charge-coupled device (EMCCD) camera, a gadolinium aluminum gallium garnet (GAGG) scintillator film, and a fluorescent microscope to measure the micro-distribution of radionuclides. A reconstruction technique was developed to determine the initial positions of alpha particles based on the pixel gray-value distributions along their trajectories. The effectiveness of this technique was validated through imaging experiments using fixed incident alpha particles. Key imaging parameters, including binning, exposure time, and optical parameters such as magnification, were systematically investigated for their impacts on imaging quality. Results indicated that increasing the binning value improved detection sensitivity but reduced spatial resolution. Shortening exposure times effectively prevented track overlap, aiding trajectory identification, counting, and analysis. Higher magnification of objective lenses enhanced the spatial resolution of the whole system but required greater sample flatness and camera sensitivity. A measurement platform was further developed to explore the cellular distribution of radioactive drugs in targeted alpha therapy. Coupled registration of trajectory and cellular images was achieved using an external Ra-223 source and A549 cells. This trajectory measurement technique is broadly applicable for analyzing the cellular distribution of radioactive drugs in targeted alpha therapy.