[OPTICAL REVIEW Vol. 8, No. 4 (2001) 301-304]

Measurement of Root Mean Square Granularity of X-ray Films Using a Commercial Film Scanner

Yasuhiro HOSOBUCHI1,* and Kazuhiko OHNUMA2

1School of Radiologic Sciences, Faculty of Health Sciences, Tokyo Metropolitan University of Health Sciences, 7-2-10, Higashi-ogu, Arakawa-ku, Tokyo, 116-8551 Japan, 2 Graduate School of Science & Technology, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba, 263-8522 Japan

(Received January 30, 2001; Accepted June 19, 2001)

Root mean square granularity of films are generally measured using a microdensito-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 densities by a diffuse densitometer and pixel values by a film scanner was obtained. 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.

Key words : rms granularity, film scanner, diffuse densitometer, standard deviation, pixel, X-ray film, screen