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Title: An algorithm to unveil the inner structure of objects concealed by beam divergence in radiographic image acquisition systems

Two main parameters rule the performance of an Image Acquisition System, namely, spatial resolution and contrast. For radiographic systems using cone beam arrangements, the farther the source, the better the resolution, but the contrast would diminish due to the lower statistics. A closer source would yield a higher contrast but it would no longer reproduce the attenuation map of the object, as the incoming beam flux would be reduced by unequal large divergences and attenuation factors. This work proposes a procedure to correct these effects when the object is comprised of a hull - or encased in it - possessing a shape capable to be described in analytical geometry terms. Such a description allows the construction of a matrix containing the attenuation factors undergone by the beam from the source until its final destination at each coordinate on the 2D detector. Each matrix element incorporates the attenuation suffered by the beam after its travel through the hull wall, as well as its reduction due to the square of distance to the source and the angle it hits the detector surface. When the pixel intensities of the original image are corrected by these factors, the image contrast, reduced by the overallmore » attenuation in the exposure phase, are recovered, allowing one to see details otherwise concealed due to the low contrast. In order to verify the soundness of this approach, synthetic images of objects of different shapes, such as plates and tubes, incorporating defects and statistical fluctuation, have been generated, recorded for further comparison and afterwards processed to improve their contrast. The developed algorithm which, generates processes and plots the images has been written in Fortran 90 language. As the resulting final images exhibit the expected improvements, it therefore seemed worthwhile to carry out further tests with actual experimental radiographies.« less
Authors:
;  [1] ;  [2]
  1. Instituto de Engenharia Nuclear - CNEN, Caixa Postal 68550, CEP 21945-970, Rio de Janeiro (Brazil)
  2. Laboratório de Instrumentação Nuclear - UFRJ, Caixa Postal 68509, CEP 21945-970, Rio de Janeiro (Brazil)
Publication Date:
OSTI Identifier:
22390503
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1625; Journal Issue: 1; Conference: 36. Brazilian Workshop on Nuclear Physics, Sao Sebastiao, SP (Brazil), 1-5 Sep 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALGORITHMS; ATTENUATION; COMPARATIVE EVALUATIONS; COORDINATES; DATA ACQUISITION; DATA ACQUISITION SYSTEMS; DATA ANALYSIS; FLUCTUATIONS; IMAGE PROCESSING; IMAGES; MATRICES; MATRIX ELEMENTS; PERFORMANCE; SOUND WAVES; SPATIAL RESOLUTION; STATISTICS; SURFACES