1. A multi-camera flat panel X-Ray detector, the detector comprising: a scintillator to convert X-Ray radiation generated by an X-Ray source into detectable radiation; at least one imaging sensor to acquire, during a linearization phase, at least two images related to the detectable radiation, at a field of view of the at least one imaging sensor, wherein the intensity of the X-Ray radiation generated by the X-Ray source is different for each of the at least two images; a light energy measurement unit to measure, during the linearization phase, substantially simultaneously with the acquiring of each of the at least two images, at least two corresponding levels of energy of the detectable radiation, wherein the light energy measurement unit is substantially linear at the range of operation; and a processing unit comprising a processor and memory, the processing unit to: obtain the at least two images from the at least one imaging sensor; obtain the at least two levels of energy from the light energy measurement unit; and calculate a inverse response function to the at least one imaging sensor based on the at least two images and on the at least two levels of energy.