Radiation is invisible. Technically, nonvisible radiation is called ionizing radiation, and visible light is called nonionizing radiation. Physicists have discovered methods of translating ionizing radioactivity into images. While scientific images of radiation have been subsequently used for medical and military purposes, artists have also captured and translated radioactivity into images. The article discusses these contesting and interlaced histories of imagining and visualizing radiation and suggests that the artists as corporeal materiality have become an indexical representation of radiation in their attempts to capture it.