1. A system for calibrating the dose response of an image acquisition device, comprising: means for generating a first self-calibration curve; means for generating a second self-calibration curve; means for generating an initial calibration; and means for performing computations including: (1) determining at least one difference or fit between the first self-calibration curve and the second self-calibration curve; (2) modifying an acquired image based on the at least one difference or fit; and (3) producing a relative calibration based on an application of the initial calibration to the acquired image.