X-ray attenuation coefficient of mixtures: Inputs for dual-energy CT

Abstract

The attenuation coefficient, μ(E) of substances, at any energy (E) of the x-ray photon, is known to depend on the electron density (ρe) and the effective atomic number (Zeff) of the material. While the dependence on ρe is known to be linear, that of Zeff is found to follow a power law (Zeff)x which makes it very sensitive to the index “x”. Several different values, lying between 3 and 4 have been suggested for the exponent x, in the existing literature. The purpose of the present investigations is to ascertain empirically the value that should be assigned to x.