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The effect of the momentum transfer on the sensitivity of a photon scattering method for the characterization of tissues
Author(s) -
Leichter I.,
Karellas A.,
Craven J. D.,
Greenfield M. A.
Publication year - 1984
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 - 10.1118/1.595473
Subject(s) - photon , compton scattering , physics , sensitivity (control systems) , momentum transfer , scattering , momentum (technical analysis) , computational physics , optics , atomic number , range (aeronautics) , atomic physics , photon energy , coherent backscattering , characterization (materials science) , materials science , finance , electronic engineering , economics , composite material , engineering
The ratio of coherent to Compton photons scattered by a tissuelike material depends on its effective atomic number. This ratio can, therefore, be used for the in vivo characterization of tissues. The intrinsic sensitivity of this measurement is defined as the change in the coherent‐to‐Compton ratio for a given change in the atomic number. The effect of the scatter angle on the sensitivity has already been described by us in a paper recently submitted to this journal. In this study, the dependence of the sensitivity on the energy of the incident photons is investigated in two ways. The first approach is quasitheoretical and is based on computations of the cross sections of the coherent and Compton scattering for various energies. The second approach is experimental and it involves the measurement of the scatter ratio from a series of K 2 HPO 4 solutions for three primary photon energies: 60, 81, and 140 keV. The combined effect of both the photon energy and the scatter angle on the sensitivity can be described by a single parameter which is the momentum transfer. It is concluded that for the limited range of the atomic numbers which apply to trabecular bone (8≤ Z ̄≤11) the momentum transfer reflects completely the effect of the scatter angle and photon energy on the sensitivity.