Modulation transfer function of the intensity distribution of the roentgen focal spot.

In roentgen image transmission systems, many factors are basically related to image quality. Some of the intensity distributions of the roentgen focal spot and its modulation transfer function (MTF) have been experimentally measured. However, no definite standardization of the intensity distribution of the focal spot, and no generalized study of relationships to the modulation transfer function, seem to have been made (see NBS Handbook No. 89 (1963)). The intensity distribution of the focal spot is in this report expanded to symmetry and anti-symmetry components on a base of rectangular function. The parameters of the symmetry and anti-symmetry components are presumed, and the relations to the modulation transfer function are clarified. Thus, the effective intensity distributions of the focal spot are standardized by the use of its modulation transfer function. These results are indispensable for the analysis and standardization of roentgen systems, such as roentgen television and cineradiographic equipment and are of basic importance for the study and interpretation of roentgen images.