Assessment of Radiographic Granularity by a Single Number

Abstract

The granularity of radiographic screen-film systems is assessed by a single number in terms of the entropy method. This method is evaluation on the basis of the precision of measurements, and in the present paper the precision is directly related to radiographic granularity which refers to both RMS granularity (the standard deviation of density fluctuations) and film contrast (the gradient of H & D curve). From the results of entropy calculations, the ability of transmission of radiographic images in two screen-film systems is obtained by comparing the values of transmitted information or the relative efficiency of transmission.