Automatic brightness compensation for x-ray imaging systems.

摘要

The brightness of an X-ray video image during fluorography is maintained at a substantially constant level varying the X-ray dose in relation to changes in the average brightness of the X-ray image. As the X-ray system approaches the limits of its imaging capability, varying the X-ray dose alone may not yield the desired brightness level. At this point, the gain applied to the video signal is increased to improve the brightness. A linear brightness taper function is used such that, as the level of video gain required to maintain constant brightness increases, the actual video gain increases by a smaller proportional amount. This function results in the brightness of the video image decreasing somewhat as the video gain is required to provide a greater degree of brightness compensation. This reduction in brightness not only provides a visual indication to the image observer that the system is approaching the imaging limits, but also creates an illusion that noise artifacts in the image are not intensifying as the video gain increases. <IMAGE>