A Comparative Evaluation of Rare-Earth Screen-Film Systems: System Speed, Contrast, Sensitometry, RMS Noise, Square-Wave Response Function, and Contrast-Dose-Detail Analysis

We evaluated the physical characteristics and contrast-dose-detail performance of 11 rare-earth and three calcium tungstate screenfilm systems. Measurements included system speed, contrast, sensitometry, RMS noise, square-wave response function, and contrast- dose-detail analysis. The major differences in physical characteristics among systems were system speed and RMS noise. Square-wave response differences were more subtle. For contrastdose- detail analysis, the rare-earth screen-film systems and the calcium tungstate system responses were significant over a limited subject contrast range as a function of detail diameter. Relative dose efficiency in the noise-limited region is a function of the properties of the screen only and is independent of the film.