Interaction of low-energy photons with biological materials and the effective atomic number.

The effective atomic numbers for total photon interaction in bone, muscle, liver, spleen, fat, and water are determined and found to decrease up to 50% as the energy increases from 10 to 200 keV. Muscle, spleen, liver, and water are found to behave in an approximately similar manner in this energy region, as far as photon interaction is concerned.