A method for the correction of lag charges in a flat-panel X-ray detector makes it possible, for each integration phase of the detector, to determine an initial read phase situated just before said integration phase. The method of the invention enables the measurement, for each integration phase, of the charges present in the detector at the corresponding initial read phase, the production of a lag image from the latent charges measured in the initial read phase and the subtraction of the lag image from the raw image. The use of the measurement of charges enables the direct correction of the lag image in the acquisition without the use of a correction module as in the prior art.