Embodiments of radiographic imaging systems and/or methods can monitor the state of calibration of a digital x-ray detector, the detector including a solid state sensor with a plurality of pixels, an optional scintillating screen and at least one embedded microprocessor. In one embodiment, a method can use a computer or the embedded microprocessor or both, for setting a calibration operating mode of the portable detector; taking a plurality of dark images in the calibration mode; determining a dark difference image between pixel readings between two of the plurality of dark images; identifying pixels in the dark difference image that differ by over a threshold amount from at least some surrounding pixels in the dark difference image as defective pixels.