The role of screen parameters and print-through in the performance of film/screen systems

Sophisticated models of the stochastic processes involved in screen/film image formation have been developed in the last few years. These models allow one to predict overall system performance and to compare this with the performance of real systems. In the case of screens these stochastic processes involve the probability of X-ray absorption, the X-ray to light photon conversion efficiency governed by the phosphor's scintillation spectrum and the subsequent scattering or absorption of the emitted light photons in the screen. In the case of systems using two screens the film's contribution to the final photographic image involves degradation of image resolution due to print-through. The authors' models allow them to quantify the degree to which this occurs and to establish an upper limit on image resolution in the absence of print-through and as a function of the peak emission wavelength of the phosphor which influences light absorption in the screen.