A new standard method for the sensitometry of X-ray screen-film-processing systems is under development by ANSI Subcommittee PI12-31. Devised not only for systems manufacturers but also for the ultimate system user, the method employs radiation qualities simulating those for X-rays emergent from human phantoms. Standard test objects are specified that approximate the primary to scatter ratios found for three commonly used techniques (chest, skull and pelvis, and extremity radiography). The method permits the determination of system speeds for each technique under scatter and under non-scatter conditions. By specifying the use of aluminum modulators with the test objects the method also measures contrast, or the system's capability of visualizing changes in object thickness.
Eric T. Clarke, Eric T. Clarke,
"A New Ansi Screen-Film-Processing Sensitometry Standard", Proc. SPIE 0127, Application of Optical Instrumentation in Medicine VI, (27 December 1977); doi: 10.1117/12.955921; https://doi.org/10.1117/12.955921