Effective atomic numbers for photon energy-absorption of some selected substances of dosimetric interest

Effective atomic numbers for photon energy-absorption of some selected substances of dosimetric interest such as cortical bone, breast tissue, ovary, eye lens, testis and soft tissue have been calculated in the energy region of 1 keV-20 MeV. Significant differences exist between the effective atomic numbers for photon interaction and photon energy-absorption in the energy region of 5-400 keV and 1-20 MeV for cortical bone, 10-150 keV for breast tissue, soft tissue, ovary, testis and eye lens. Since effective atomic numbers for photon energy-absorption represents the absorbed dose it is preferable to use the same instead of commonly used effective atomic numbers for photon interaction in medical radiation dosimetry for the calculation of absorbed dose in radiation therapy. (author)