[Light production from intensifying screens (theoretical and experimental aspects)]

The authors show the results of an experimental study on the light conversion efficiency of the absorbed energy from an incident X-ray beam by different kinds of intensifying screens. They stress that the absolute speed curves drawn for each intensifying screen, express (in the energy range 10 to 100 keV) the light output for an incident X-ray of a certain energy value. In this way, the knowledge of the X-ray tube emission spectra for a fixed kVp allows to forecast with good accuracy, the light output and the emerging spectra from an intensifying screen. They emphasize the importance of the K-edge (K shell electrons binding energy) as a factor affecting the phosphors behaviour both for what concerns the radiation filtration and the light conversion efficiency of the absorbed radiation.