Z-dependence of photon interactions in simulated materials

The Z-dependence of photon cross sections and the variation of Z-exponents with energy and elemental composition have been studied with an emphasis on tissue-equivalent materials. The validity of the evaluated Z-exponents and effective atomic numbers have been tested by means of measured attenuation coefficients in simulated materials in the energy range 13–60 keV. To characterize a phantom material an empirical relation for the mass attenuation coefficient previously suggested by this group has been confirmed.