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Energy dependence of effective atomic numbers for photon energy absorption and photon interaction: Studies of some biological molecules in the energy range 1 keV–20 MeV
Author(s) -
Manohara S. R.,
Hanagodimath S. M.,
Gerward L.
Publication year - 2008
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2815936
Subject(s) - chemistry , absorption (acoustics) , radioluminescence , photon energy , atomic physics , photon , analytical chemistry (journal) , materials science , physics , scintillator , optics , organic chemistry , detector , composite material
Effective atomic numbers for photon energy absorption,Z PEA , eff, and for photon interaction,Z PI , eff, have been calculated by a direct method in the photon‐energy region from 1 keV to 20 MeV for biological molecules, such as fatty acids (lauric, myristic, palmitic, stearic, oleic, linoleic, linolenic, arachidonic, and arachidic acids), nucleotide bases (adenine, guanine, cytosine, uracil, and thymine), and carbohydrates (glucose, sucrose, raffinose, and starch). TheZ PEA , effandZ PI , effvalues have been found to change with energy and composition of the biological molecules. The energy dependence of the mass attenuation coefficient,Z PEA , eff, and the mass energy‐absorption coefficient,Z PI , eff, is shown graphically and in tabular form. Significant differences of 17 % − 38 % betweenZ PI , effandZ PEA , effoccur in the energy region 5–100 keV. The reasons for these differences, and for usingZ PEA , effrather thanZ PI , effin calculations of the absorbed dose, are discussed.