A K edge filter technique for optimization of the coherent‐to‐Compton scatter ratio method
作者:
G. Harding,
R. Armstrong,
S. McDaid,
M. J. Cooper,
期刊:
Medical Physics
(WILEY Available online 1998)
卷期:
Volume 22,
issue 12
页码: 2007-2014
ISSN:0094-2405
年代: 1998
DOI:10.1118/1.597497
出版商: American Association of Physicists in Medicine
数据来源: WILEY
摘要:
The ratio method involves forming the ratio of the elastic to inelastic x‐ray scatter signals from a localized region of a scattering medium to determine its mean atomic number. An analysis is presented of two major error sources influencing the ratio method: firstly statistical (photon) noise and secondly multiple scattering and self‐attenuation of the primary and scatter radiations in the medium. It is shown that a forward scattering geometry minimizes errors of both types for substances composed of elements with low and medium atomic number. However, owing to the small energy separation (∼100 eV) of coherent and Compton scatter for this geometry, they cannot be distinguished directly with semiconductor (e.g., Ge) detectors. A novel K edge filter technique is described which permits separation of the elastic and Compton signals in the forward‐scatter geometry. The feasibility of this method is demonstrated by experimental results obtained with Ta fluorescence radiation provided by a fluorescent x‐ray source filtered with an Er foil. The extension of this technique to the “invivo” measurement of low momentum transfer inelastic scattering from biological tissues, possibly providing useful diagnostic information, is briefly discussed.
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