Method of imaging the atomic number of a sample

摘要

A method of obtaining an atomic number image of an unknown material. A plurality of calibration materials which have a plurality of different known atomic numbers and densities are scanned with a CAT at first and second energies to determine the attenuation coefficients for the plurality of calibration materials at these energies. The energy-dependent coefficients at the first and second energies are determined from the attenuation coefficients for the plurality of calibration materials at the first and second energies according to a predetermined relation. The unknown material is scanned with a CAT at the first and second energies to determine the attenuation coefficients at a plurality of points in a cross section of the unknown material at these energies. The determined energy-dependent coefficients and the determined attenuation coefficients for the unknown material at the first and second energies are used to determine an atomic number image for the unknown material.