Measuring device to determine the dose. The radio-photoluminescence effect which is the property of certain substances to emit fluorescent light of greater wave length upon irradiation with ultraviolet light when previously exposed to ionizing radiation, is used to determine the dose. Silver-activated metaphosphate glasses – glasses made of alkaline and alkaline earth phosphates with some percent of silver metaphosphate – show this photoluminescence effect for example. The intensity of the fluorescent light is proportional over wide areas of the irradiated dose.