The effects of energy dependence on radiographs

The objective of this work was to ascertain the effects of energy dependence on X-ray radiographs for real-time radiography applications. More specifically, it was to determine if this energy dependence must be considered in accurately predicting radiographs. The energy dependent characteristics of the x-ray source, the object being radiographed, and the x-ray-to-light conversion screens were considered. The energy dependence of the source was characterized analytically and was also characterized experimentally but with limited success. The effects were explored by first simulating a one dimensional intensity profile of a radiograph assuming no energy dependence, i.e., the monochromatic condition, and then simulating the profile assuming the polychromatic condition. These two profiles were then compared to a profile derived from an actual radiograph taken under similar conditions. The results showed that the polychromatic prediction more closely resembled the actual radiograph than did the monochromatic prediction for this test case. This was the case because the effective energy of the x-rays vary as a function of the path length through the object and because the monochromatic assumption was unable to account for the effects of the intensifying screens in the imaging process.