It has been revealed in this study that the sensitivity of newly developed composite grains with tabular silver iodide grains as hosts and epitaxially formed silver bromide microcrystals as guests is high enough in photothermographic materials to realize a blue medical x-ray film-screen system in combination with BaFBr:Eu fluorescent radiographic intensifying screen. Beside the fact that the quality of the system image is comparable with that of conventional ones, the image stability as well as the haze of the new system is satisfactory, in spite of the fact that the new system uses photothermographic materials, since the grains used as photosensors are fixed during thermal development.