Examination of energy subtraction method by using diffracted monochromatic x rays

Abstract

The purpose of this research is to apply monochromatic x rays to the energy subtraction (ES) method. The ES method is a technique that eliminates an image of an arbitrary material by subtracting two images acquired by x rays with different energy owing to a peculiar energy dependence of an absorption coefficient of each material. Namely, the ES method allows us to identify each material. The most ideal ES method can be carried out using two kinds of energy of monochromatic x rays. However, in general, the white x rays is used under clinical conditions, so the materials that have the same absorption coefficient are sometimes presented as different ones because of the influence of the x-ray-beam hardening. Using monochromatic x rays will improve the power to discriminate materials having the similar absorption coefficient. So, use of diffracted monochromatic x rays generated with a diffraction single crystal is the most suitable method in clinical situations.

In the present study, the ES processing uses the profile curve obtained by the two shot method. Influence of the beam hardening was evaluated from a profile curve of monochromatic x rays and white x rays after ES processing. The result shows that the use of monochromatic x rays has the high ability to identify each material.