This International Standard applies to ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIERS for medical use, as components of diagnostic X-RAY EQUIPMENT. This International Standard describes a method of determining the DETECTIVE QUANTUM EFFICIENCY (DOE) of X-RAY IMAGE INTENSIFIERS by analysis of the single gamma-ray photon scintillation pulse-height spectrum. The method of this standard applies only to ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIERS having output radiance decay rates approximately equal to or faster than that of a P-20 phosphor.