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Proceedings Paper

A novel algorithm for material discrimination using a dual energy imaging system
Author(s): Kenneth Fu; Dale Ranta; Clark Guest; Pankaj Das
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Paper Abstract

Dual energy imaging is a technique whereby an object is scanned with X-rays of two interleaved energies to extract information about the object's atomic composition (Z). This technique is based on the fact that the X-ray absorption coefficient decreases with X-ray energy for low-Z materials, but begins to increase for high-Z materials due to the onset of pair production. Methods using the ratio of the attenuations of high-energy to low-energy images as an indicator of Z value have been proposed by several people. However, the statistical errors associated with the systems make those indicators unreliable. Methods that calculate the probability of high Z encounter a problem of what is the threshold probability to call high Z to minimize both miss and false alarm. We have developed an "adaptive regional masking" method that avoids the predicament of a single threshold. Our method is adaptive because the threshold for determining high Z varies adaptively in different regions on the image. The "mask" refers to the location of objects in the thickness map that mask to possible high-Z regions. Adaptive thresholding improves detection, while masking reduces false alarms. Test results show an increased accuracy of high-Z detection using this approach. In this paper, we discuss the approach and show some sample test results illustrating the effectiveness of the method.

Paper Details

Date Published: 4 September 2009
PDF: 11 pages
Proc. SPIE 7445, Signal and Data Processing of Small Targets 2009, 744513 (4 September 2009); doi: 10.1117/12.825344
Show Author Affiliations
Kenneth Fu, Univ. of California, San Diego (United States)
Dale Ranta, SAIC (United States)
Clark Guest, Univ. of California, San Diego (United States)
Pankaj Das, Univ. of California, San Diego (United States)

Published in SPIE Proceedings Vol. 7445:
Signal and Data Processing of Small Targets 2009
Oliver E. Drummond; Richard D. Teichgraeber, Editor(s)

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