RGB-colored material discrimination for radiography by multi-monochromatic spectroscopy

Abstract

We have tried to estimate the power of the material discrimination by performing the radiographs and CT images with using the diffracted monochromatic x rays. Moreover these images were applied to energy subtraction method and high material discriminations were shown. Therefore, it is indicated that the diffracted monochromatic x rays have high material discriminations in the clinical situations although their exposure is low. So we attempt to perform the new colored material discrimination images by using the multimonochromatic x rays. When white x rays are incident on the diffraction single crystal, only the photons of energy followed Bragg's law can be obtained as monochromatic x rays. At this time, since the photons with this energy and photons with integral multiples of this energy simultaneously satisfies this law, the two or more peaks of monochromatic x rays at equal intervals (i.e. multi-monochromatic x rays) can be observed by increasing the maximum energy of incident white x rays. Each material has peculiar mass attenuation coefficients dependent on the incident-photon energies. The gradient between the two values of these attenuation coefficients are also intrinsic. In this study the two attenuation coefficients of 30 and 50 keV were selected, and this gradient of two values was named the "attenuation gradient(s)" The effective atomic number can be specified by comparing these attenuation gradients to the values of the measured-spectral absorption data. Moreover, these estimated effective atomic numbers were converted to the hue (RGB color) values. The various color images compared with their gray-scaled radiographs were shown the high power of the material discriminations. © 2009 Springer-Verlag.