Measurement of root mean square granularity of X-ray films using a commercial film scanner

Root mean square granularity of films are generally measured using a microd ensito-meter, although it is costly and not easily available. To solve the cost problem, we tried to use an inexpensive commercial film scanner. Films with different densities were prepared and the relationship between densit ies by a diffuse densitometer and pixel values by a film scanner was obtain ed. We found that a linear relationship exists between rms granularity and a corrected standard deviation of pixel value that is available as an index granularity.