Some characteristics of the line spread-function and modulation transfer function of medical radiographic films and screen-film systems.

Abstract

The line spread-function (LSF) and modulation transfer function (MTF) of a screen-film system convey important information regarding the light diffusion in the system, which is one of the parameters influencing overall image quality. The LSF of a screen-film system is the relative illuminance distribution in the image of a narrow slit. Thus, the LSF is a direct measure of light diffusion in screens and film. The MTF is a measure of the ability of the systems to image, frequency for frequency, a radiation pattern in which intensity varies sinusoidally with distance in one dimension in the object plane. By definition, the LSF and MTF of screen—film systems are parameters that can be used as a measure of the image deterioration due to light diffusion only. The effect on image quality of other system characteristics, such as film contrast and absorption of x-ray quanta in the screens resulting in quantum mottle, is not measured by the LSF and MTF. Thus, the LSF and MTF do not, in themselves, provide a measure...