Influence of Microdensitometer on the Measurement of the Line Spread Function

Abstract

The characteristic curve and the multiple-exposure method (MEM) are most commonly used in order to transform the density distribution of the slit image into the line spread function (LSF) in measuring the LSF of radiographic screen-film systems. SAKURA PDM-5 or SAKURA PDS-15 is generally used as a microdensitometer to measure the characteristic curve in that method. However, the density dependence was found out in using SAKURA PDS-15. The new method presented here made it possible to measure the LSF completely independent of any kind of microdensitometer. This method is characterized by using "micro-blackness characteristic (MBC) curve", together with the preexposure method (PEM), both of which were developed by Uchida. This method was proved useful by our experiment to obtain the LSF almost independent of any microdensitometer. The LSF obtained by the PEM well corresponded with that obtained by the MEM.