Spectral Computed Tomography Based on Semi-Monochromatic Imaging

Spectral computed tomography (CT) advances conventional CT by enabling material-specific imaging. This technique leverages the energy dependence of X-ray attenuation. However, the polychromatic spectra typical for laboratory and industrial CT limit the sensitivity of spectral CT methods. In this work, band-pass filtering of X-ray energies in a laboratory CT scanner is explored for the purpose of increasing spectral sensitivity. In the Rigaku nano3DX, X-ray generation is tuned to maximize the fraction of characteristic X-rays in the overall energy spectrum. This fraction is further enhanced by strategic filtering and processing of CT datasets to produce semi-monochromatic images centered on characteristic emission lines relevant to the analysis. Reconstructed CT data can then be interpreted as linear attenuation coefficients for the given emission line in the scanned volume, with potential for further spectral and spectroscopic applications in a laboratory setting, particularly for low-Z materials.