The optical and noise properties of radiographic screen-film systems have often been evaluated by concepts and techniques related to Fourier analysis. Figure 1 illustrates the physical characteristics of these properties. The point spread function (PSF), which is the two dimensional representation of the optical property of the screen-film system, has not been applied experimentally for evaluation. The screen-film system is generally considered to be isoplanatic and isotropic; therefore, the line spread function (LSF) in an arbitrary direction can be used. This function is much simpler to measure than the PSF. In the spatial frequency domain, the optical property is evaluated by the modulation transfer function (MTF), which is the absolute value of the Fourier transform of the LSF. Other optical characteristics such as the edge response are usually related to the LSF or the MTF.