Quantum Noise-Limited Images In Screen Film Systems

The limits imposed on the spatial resolution obtained with screen-film systems for low contrast images are determined primarily by x-ray quantum noise rather than by the spatial response (MTF curve) of the system. For 40 keV x rays incident on a HiPlus/XRP screen-film system, the x-ray quantum noise limits the spatial resolution in the density region of unity from approximately 0.2 to 1 line pair per mm for film density differences respectively in the region from .02 to 0.1. By comparison, the MTF effect over most of this region of density differences, produces less than a 10 percent degradation of the spatial resolution.