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Nondestructive Inspection of Thin, Low-Z Samples using Multiplexed Compton Scatter Tomography

Published online by Cambridge University Press:  10 February 2011

B. L. Evans ,
J. B. Martin  and
L. W. Burggraf
B. L. Evans
Affiliation:
Air Force Institute of Technology, Department of Engineering Physics, 2950 P St. Wright-Patterson AFB, OH 45433
J. B. Martin
Affiliation:
Air Force Institute of Technology, Department of Engineering Physics, 2950 P St. Wright-Patterson AFB, OH 45433
L. W. Burggraf
Affiliation:
Air Force Institute of Technology, Department of Engineering Physics, 2950 P St. Wright-Patterson AFB, OH 45433
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Abstract

The viability of a Compton scattering tomography system for nondestructively inspecting thin, low Z samples for corrosion is examined. This technique differs from conventional x-ray backscatter NDI because it does not rely on narrow collimation of source and detectors to examine small volumes in the sample. Instead, photons of a single energy are backscattered from the sample and their scattered energy spectra are measured at multiple detector locations, and these spectra are then used to reconstruct an image of the object. This multiplexed Compton scatter tomography technique interrogates multiple volume elements simultaneously. Thin samples less than 1 cm thick and made of low Z materials are best imaged with gamma rays at or below 100 keV energy. At this energy, Compton line broadening becomes an important resolution limitation. An analytical model has been developed to simulate the signals collected in a demonstration system consisting of an array of planar high-purity germanium detectors. A technique for deconvolving the effects of Compton broadening and detector energy resolution from signals with additive noise is also presented. A filtered backprojection image reconstruction algorithm with similarities to that used in conventional transmission computed tomography is developed. A simulation of a 360–degree inspection gives distortion-free results. In a simulation of a single-sided inspection, a 5 mm × 5 mm corrosion flaw with 50% density is readily identified in 1-cm thick aluminum phantom when the signal to noise ratio in the data exceeds 28.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 503: Symposium JJ – Nondestructive Characterization of Materials in Aging Systems , 1997 , 297
Copyright
Copyright © Materials Research Society 1998

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References

REFERENCES

[1] Lawson, L., “Compton x-ray backscatter depth profilometry for aircraft corrosion inspection,” Materials Evaluation, pp. 936–941, August 1995.Google Scholar
[2] Manning, O., Stanley, J., Smith, D. and Little, F., Final Report, US Air Force Wright Laboratories, Contract #F33615–87-C-5249, 1995.Google Scholar
[3] Ong, P.S., Anderson, W.L., Cook, B.D. and Subramanyan, R., “A Novel X-Ray Technique for Inspection of Steel Pipes”, J. Nondestructive Eval., Vol.13, 1994, pp. 165–165.Google Scholar
[4] Kondic, N.N., Jacobs, A.M. and Ebert, D., “Three-dimensional density field determination by external stationary detectors and gamma sources using selective scattering,” Proc. 2nd Int. Topical Mtg. On Nuc. React. Therm.-Hydr., pp. 1443–1455, 1983.Google Scholar
[5] Norton, S.J., “Compton scattering tomography,” J. Appl. Phys, vol. 76, no. 4, pp. 2007–2015, August 1994.Google Scholar
[6] Prettyman, T.H., Gardner, R.P., Russ, J.C. and Verghese, K., “A combined transmission and scattering approach to composition and density imaging,” Appl Radiat. Jsot., vol. 44, no. 10/11, pp. 1327–1341, 1993.Google Scholar
[7] Arendtsz, N.V. and Hussein, E.M.A., “Energy-spectral Compton scatter imaging (parts I & II),” IEEE Trans. Nucl. Sci., vol. 42, no. 6, pp. 2155–2172, Dec. 1995.Google Scholar
[8] Lawson, L.R., “Flux Maximization Techniques for Compton Backscatter Depth Profilometry”, J. X-Ray Sci. and Tech., Vol.4, pp. 18–36, 1993.Google Scholar
[9] Herman, G.T., Image Reconstruction From Projections, New York: Academic Press, 1980.Google Scholar
[10] Barrett, H.H. and Swindell, W., Radiological Imaging, New York: Academic Press, 1981.Google Scholar
[11] Ortec, Eg&g, Modular Pulse-Processing Electronics and Semiconductor Radiation Detectors, product catalog. Oak Ridge, TN: EG&G, 1997.Google Scholar
[12] Cooper, M.J., “Compton scattering and electron momentum,” Contemporary Physics, vol. 18, no. 5, pp. 489–517, 1977.Google Scholar
[13] Cesareo, R., Hanson, A.L., Gigante, G.E., Pedraza, L.J. and Mathaboally, S.Q.G., “Interaction of keV photons with matter and new applications,” Physics Reports, vol. 213, no. 3, pp. 118–178, 1992.Google Scholar
[14] Biggs, F., Mendelsohn, L.B. and Mann, J.B., “Hartree-Fock Compton profiles,” Atomic Data and Nuclear Data Tables, vol. 16, no. 3, pp. 202–222, Sept. 1975.Google Scholar
[15] Knoll, G. F., Radiation Detection and Measurement, New York: John Wiley & Sons, 1989.Google Scholar
[16] Andrews, H.C. and Hunt, B.R., Digital Image Restoration, Englewood Cliffs, NJ: Prentice-Hall, 1977.Google Scholar
[17] Evans, B.L., Martin, J.B., Burggraf, L.W. and Roggemann, M.C., “Nondestructive Inspection Using Compton Scatter Tomography”, to be published in Proc. 1997 IEEE Nucl. Sci. Symp., Nov 10–13, 1997, Albuquerque, NM, USA.Google Scholar
[18] Cho, Z.H., Jones, J.P. and Singh, M., Foundations of Medical Imaging, New York: John Wiley & Sons, 1993.Google Scholar
[19] Shepp, L.A. and Vardi, Y., “Maximum likelihood reconstruction for emission tomography,” IEEE Trans Med. Imaging, vol. 1, no. 2, pp. 113–122, Oct. 1982.Google Scholar