Digital computerized radiography (DCR) combines conventional radiography with digitized computer imaging. Three basic elements of radiography include a radiation source, the object being evaluated, and a sensing material (Fig. 1). The object in the diagram is a plate of uniform thickness that contains an internal flaw with absorption characteristics different from those of the surrounding material. Radiation from the source is absorbed by the plate as the radiation passes through it; the flaw and surrounding material absorb different amounts of radiation. Thus, the intensity of radiation that impinges on the sensing material in the area beneath the flaw is different from the amount that impinges on adjacent areas. This produces an image, or shadow, of the flaw on the sensing material.


