A Method for Classifying X-Ray Film

摘要

A study has been conducted to evaluate the parameters that could be used to characterize X-ray film. Factors such as speed, graininess, resolution, contrast and uniformity of emulsion are discussed. Recently developed methods of measuring resolution such as the modulation transfer function will be reviewed. At the present time it is felt that the characteristics of speed and average gradient should form the basis of a film classification system. It is proposed that a contrast-speed index equal to G times the square root of r be used to characterize X-ray film. G is defined as the average gradient between two arbitrary densities d1 and d2, and r is the number of roentgens necessary to produce the density midway between d1 and d2. (Author)