Abstract: A radiation imaging device including a photostimulable phosphor which is a glass including active cations that release light having a wavelength in the blue colour or ultra-violet region when those parts of the glass which have been stimulated by radiation, and a radiation source to irradiate the phosphor and an excitation light source to photostimulate the phosphor. The radiation source may be X-rays, .gamma.-rays, .alpha.-rays, .beta.-rays, electron beams, neutron beams, ion beams, ultra-violet rays having an energy equal to or greater than the band gap of the glass are excited by visible or infra-red light. Ce.sup.3+, Eu.sup.2+ can be used as the active cation, and are preferably included in an amount of 10 mole % or less of all the cations, and particularly preferably in an amount in the range of 0.001 to 2 mole %.