An x-ray sensor 60 includes a phosphorescent phosphor 601 susceptible to x-ray irradiation 12 for forming an image in the phosphor, the phosphor having a decay period 71 persistent after an irradiation period 75. A photoelectric sensor array 603 is arranged to receive phosphorescent emission from the phosphorescent phosphor 601 corresponding to the image. The photoelectric sensor array is gated off for a gated period 72 during at least some of, or exceeding, the irradiation period 75 to disregard output from the photoelectric sensor array means generated during at least some of the irradiation period to reduce the effect of direct x-ray irradiation of the photoelectric sensor array. A signal is at least primarily output from the sensor from persisting phosphorescence from the phosphor during the decay period.
