Photo-stimulable Phosphor

A special phosphor was designed for the Imaging Plate. A certain substance has been known to emit light when irradiated with radiation, UV rays or an electron beam, or when heated, or mechanically hit or stimulated by chemical reaction in some cases. Materials of this kind are generally called fluorescent substances. In particular, the substances that are powders with practical applications are often called phosphors. A phosphor emits light when stimulated by radiation, for example. The light disappears instantaneously when the stimulation ceases. This phenomenon is called fluorescence. Some of the phosphors, however, continue emitting lights for a while after the stimulation stops, which is called phosphorescence. Luminescence incorporates both of these light emission phenomena. The luminescence characteristics, specifically those of fluorescence and phosphorescence, should be taken into account when developing phosphors for practical usage. And depending on the application, these characteristics are accurately adjusted by varying the phosphor composition or manufacturing conditions.

The phosphor used for the Imaging Plate has special properties differing from those previously known, but which have not yet been put to practical use. It utilizes the photostimulated luminescence (PSL) phenomenon that is neither fluorescent nor phosphorescent. This phenomenon involves a substance that re-emits light upon a second stimulation of light that has a longer wavelength than the luminescence wavelength of the first stimulation, for example, radiation. This PSL phenomenon satisfies our basic concept of the Imaging Plate as an X-ray image sensor, which stores the first radiation information and releases that information as light.

Back to Imaging Plate Overview