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Sample mass determination using Compton‐ and total scattered excitation radiation for energy‐dispersive x‐ray fluorescent analysis of trace elements in soft tissue specimens
Author(s) -
Cox Hollace L.,
Ong Poen S.
Publication year - 1977
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 - 10.1118/1.594388
Subject(s) - compton scattering , atomic number , effective atomic number , excitation , radiation , photon , scattering , absorption (acoustics) , atomic physics , spectroscopy , analytical chemistry (journal) , chemistry , optics , physics , quantum mechanics , chromatography
Compton profiles and total scattered intensities have been measured to determine the total sample mass, analyzed by an x‐ray probe energy‐dispersive analyzer. Under photon excitation, fluorescent x rays are emitted from the trace elements in a biological matrix. From incident radiation, the number of photons which are Compton and elastically scattered by low‐atomic‐number elements is directly proportional to the total specimen mass. Tissue specimen masses have been measured from Compton intensities using Zr Kα and Ma Kα excitation x rays and mass calibration standards based upon carbon scattering. This procedure has been extended to include lower‐energy excitation radiation, such as Cu, where the resolution of an energy‐dispersion system requires that the total scattered intensity be used to determine the sample mass. Trace element weight‐fraction concentrations are determined from this scheme with precisions of 1% in 2%, relying only upon information contained in the energy‐dispersive x‐ray spectrum. By adjusting for the difference between tissue and carbon scattering, the accuracy of the elemental weight‐fraction concentrations is brought to within l0% of elemental concentrations measured by atomic absorption spectroscopy, for samples weighing up to 25 mg. In the case of heavier samples, absorption corrections are necessary to achieve this accuracy.