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Proceedings Paper

Absorption And Scattering Properties Of Elemental Filters For X-Ray Beams
Author(s): A. Karellas; N. Tan; M. A. Davis; C. J. D'Orsi
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Paper Abstract

Suppression of the low energy component of diagnostic x-ray spectra is achieved in most cases by using aluminum filtration. The use of heavier elements alone or in conjunction with aluminum has been suggested to improve image contrast and reduce radiation dose. Previous studies have attempted to determine the optimum x-ray filter on the basis of the total attenuation coefficients alone. In this study we characterize x-ray filters by accounting for their absorption and scattering properties. Our results show that the standard aluminum filters produce scatter radiation which can account for 10-15% of all scatter. This effect is especially significant in radiographic procedures such as mammography, where scattered photons contribute to a reduction in radiographic contrast and lesion detectability. Heavier filters such as lead can reduce this scatter component by as much as 80%. Coherent scattering at an angle from 0 to 15° is responsible for the major portion of the scatter from aluminum filters at small scatter angles. This is demonstrated by the ratio of the scatter cross-section in a small volume element in the forward direction to the total cross-section for both coherent and incoherent scattering. We have concluded that an optimum filter can be selected on the basis of its ratio of the photoelectric to scatter components of attenuation. This criterion may also be extended to tissue compensating filters used in radiography for exposure equalization and computed tomography filters.

Paper Details

Date Published: 12 June 1986
PDF: 6 pages
Proc. SPIE 0626, Application of Optical Instrumentation in Medicine XIV and Picture Archiving and Communication Systems, (12 June 1986); doi: 10.1117/12.975389
Show Author Affiliations
A. Karellas, University of Massachusetts Medical Center (United States)
N. Tan, University of Massachusetts Medical Center (United States)
M. A. Davis, University of Massachusetts Medical Center (United States)
C. J. D'Orsi, University of Massachusetts Medical Center (United States)


Published in SPIE Proceedings Vol. 0626:
Application of Optical Instrumentation in Medicine XIV and Picture Archiving and Communication Systems
Samuel J. Dwyer; Roger H. Schneider, Editor(s)

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