Mineralogy evaluation and segmentation using dual-energy microtomography

Computed tomography is a nondestructive technique that allows the visualization of internal structures of a sample. However, the attenuation coefficient of a material to radiation, shown in grayscale levels, can be interpreted as the combination of parameters of density and atomic number. Thus, the separation of different structures of equal attenuation is no simple task, requiring prior knowledge of the sample composition, which is usually not available. By calibration of a high-resolution microtomographic system through the dual-energy technique, using materials of known composition, it is possible to identify and segment images to obtain the spatial distribution of parameters of density and atomic number. As the combination of these two data is unique to each material, it allows the identification and separation of regions, indistinguishable in common grayscale images obtained by microtomography. In this work, we developed a methodology for the evaluation of the dual-energy technique, as well as assessment, segmentation, and reconstruction of images on a scale of density and atomic number; added to this, we sought to develop a code in MatLab® for data, image processing, and mineralogical segmentation. The results show the capabilities of the dual-energy technique, combined with the microtomography technique, to obtain information on the composition of the sample, its three-dimensional spatial distribution, and separation of structures of the same composition. Copyright © 2015 John Wiley & Sons, Ltd.