Study of Quantitative Elemental Analysis of Monochromatic X-Ray CT Using Synchrotron Radiation

X-ray computed tomography (CT), based on monochromatized synchrotron radiation as an X-ray source, provides spatial distributions of a specific element using the difference between two CT images taken just above and below the absorption edge energy of the element. We have studied a quantitative analytical function for an element by measuring X-ray CT images of a model sample using the subtraction method. The differential CT value, which is seen as the shading intensity in the differential CT image, is proportional to the concentration of the specific element. Both spatial distributions and concentrations of the specific element can be nondestructively observed. Barium concentrations in an optical waveguide were obtained, and the relation between the concentration and the refractive index was examined.