Visualization method for radiographic films through silver intensity mapping using X‐ray fluorescence

Abstract

Radiographic films have a large range of applications. In many of these applications, the behavior of characteristic curves is very important for assessing the image quality and radiography setup. Radiographic film digitization and visualization are always performed by light transmission, and the characteristic curve is known as a behavior of optical density as a function of the radiation exposure. Because optical density is a function of metallic silver generated by chemical development in silver halides, when an image is visualized by light transmission, a silver amount map is indirectly seen. However, this measurement is limited by the optical instrument, and a very weak light signal cannot be distinguished from background light or background noise. In this way, highly exposed films can contain areas with different silver concentrations, but this cannot be seen because the optical density measurement is limited. One of the ways through which it is possible to overcome such limitation is to use a different method for ascertaining the quantity of silver remaining on the developed films, and one of the quantitative techniques that suit this purpose is X‐ray fluorescence (XRF). The purpose of this paper is applying μ‐XRF so as to obtain a point‐by‐point silver intensity map to detect objects with low optical contrast on conventional radiographic films. The results of this work have shown a higher linear range in measurement using XRF, and as consequence, small objects and details in low‐contrast or overexposed radiographic images could be visualized by the silver mapping technique, and the same results could not be achieved using light transmission methods. A first approach about spatial resolution and contrast was made showing strong and weak points of this way to scan radiographic films. Copyright © 2017 John Wiley & Sons, Ltd.