title: Effective atomic numbers for low-energy total photon interactions in human tissues.
abstract: A new method is introduced in which the total photon interaction cross sections per electron of human tissues are used to define effective atomic numbers for blood, bone, brain, fat, heart, kidney, liver, lung, muscle, ovary, pancreas, spleen, and water. These effective atomic numbers are equal within 4% from 10 to 200 keV in each soft tissue, whereas for bones of different chemical compositions the variation ranges from 2.86% to 5.03%. This effective atomic number definition is less energy dependent than a previous definition based on the total photon interaction cross section per atom averaged over all elements in the tissue, from which the computed effective atomic numbers varied by as much as 50% (in bone) as a function of photon energy over the energy range from 10 to 200 keV.
authors: Johns Hopkins Hospital, Department of Radiation Oncology, Baltimore, Maryland 21205.
authors: N C
authors: NC
authors: Yang
authors: P K
authors: PK
authors: Leichner
authors: W G
authors: WG
authors: Hawkins
mesh_terms: D000273:Adipose Tissue / Q000528:radiation effects; D001769:Blood / Q000528:radiation effects; D001842:Bone and Bones / Q000528:radiation effects; D001921:Brain / Q000528:radiation effects; D005260:Female; D006801:Humans; D007668:Kidney / Q000528:radiation effects; D008099:Liver / Q000528:radiation effects; D008168:Lung / Q000528:radiation effects; D009132:Muscles / Q000528:radiation effects; D010053:Ovary / Q000528:radiation effects; D010179:Pancreas / Q000528:radiation effects; D011827:Radiation; D013154:Spleen / Q000528:radiation effects; D014867:Water / Q000528:radiation effects; D014894:Weights and Measures
chemical_list: D014867:Water