An application of multivariate moment-generating functions to the analysis of signal and noise propagation in radiographic screen-film systems.

Previous studies [J. Opt. Soc. Am. 4A 895-901 (1987)] have shown the utility of multivariate moment-generating functions for analyzing the influence of stochastic amplifying and scattering mechanisms on the transfer of signal and noise through multistage imaging systems. Recently, these studies were extended to include cases in which the amplification or scattering parameters are themselves stochastic variables [J. Opt. Soc. Am. 6A, 1156-1164 (1989)]. In this paper we consider a special case in which amplification is followed by scattering such that the same random variable which characterizes the parameters of each amplification process also characterizes the parameters of the subsequent scattering of the amplified output events. In radiographic imaging, this can be used to describe the physics of the depth dependence of emission efficiency and light scatter in x-ray intensifying screens, which was originally treated by Lubberts [J. Opt. Soc. Am. 58, 1475-1483 (1968]). In this work Lubberts' original results are rederived in a more general form. They are then illustrated in terms of a diffusion model [Appl. Opt. 12, 1865-1870 (1973)] for light scatter within the intensifying screen.