Image properties of polycrystalline storage films.

Polycrystalline storage films are applied in various fields of x-ray radiography. Depending on the application, different requirements exist for the sensitivity and spatial resolution of the film, and these are related to light scattering in the film. Scattering is controlled by optical properties of the storage medium, e.g., the scattering length by the grain size, the absorbance by the choice of the binder, and the geometric boundary conditions by the film thickness. A method treating the scattering of light as a diffusionlike process is presented. The sensitivity, resolution, and other image properties are determined from the optical properties. The influence of the scattering length, absorbance, and thickness on image parameters is calculated and discussed. The results indicate that optimizing the image properties of the film can be achieved by a reduction of the absorbance and an increase in film thickness to the penetration depth of the x rays. Furthermore, it is shown that the resolution of the film can be set strictly according to the requirements of an individual application if the scattering length in the medium is adjusted.