Digital radiography is a general term describing any projection radiological system in which the image exists in digital form at some stage between acquisition and viewing. In an earlier form, radiographic films were dig itized in an attempt to enhance and redisplay information of interest. The field has evolved to its current state, in which X-ray signals are detected electronically, converted to digital form, and processed prior to being recorded and displayed. A primary goal of digital radiography is the re moval of interfering effects from secondary structures in an image, so that...