Linear attenuation coefficients of tissue-equivalent materials of differing compositions for low energy photons.

Total linear attenuation coefficients of three tissue equivalent materials differing in their fat contents were experimentally determined for low energy photons in the range 13-51 keV. It is found that their variations with photon energy for each of these materials are describable by two distinct power functions with the validity ranges being (13-23 keV) and (32-51 keV), respectively. Therefore, to adequately represent the variation of total linear attenuation coefficients over the full photon energy range i.e., 13-51 keV, a sum of two power functions is needed. Least squares fitted equations to the entire experimental data are thus included. For muscle, the experimental data show a reasonably good agreement with the theoretically computed values that are available in literature.