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25 July 2008

Answer to Question #4427 Submitted to "Ask the Experts"

Category: Industrial Radiation — Industrial Applications

The following question was answered by an expert in the appropriate field:

I wish to carry out tomography on a gas-liquid (water)-solid system,wherein,a gas (air) and a solid (quartz/sand or glass beads) having wide variations in density are encountered, thereby requiring special
attention towards the type of source and its strength for a particular material. In short I wish to conduct dual-energy tomography. Can you help me with some suggestions or references wherein I can find out
the basics about dual energy tomography and related things about it.

Would it be neccessary to use two different types of sources at the same time?

Can the attenuation caused by air and sand/quartz or glass beads be quantified separately?

It sounds like the materials (water, air, glass) that you want examined are suitable for conventional/medical CT examination (computed-tomography examination), unless you desire extremely fine spatial resolution. If you can transport the sample to a nearby hospital that has a CT scanner, you might ask if someone there could check it out for you. If you have other special considerations that absolutely require dual-energy tomography, see the following references for more details:

Hoover RB (NASA Marshall Space Flight Ctr, Huntsville, AL), Tate M (Princeton Univ, Princeton, NJ), eds. X-ray and UV detectors. In: SPIE Proceedings Vol. 2278; ISBN: 0-8194-1602-9; 266 pp; published 1994; Meeting Date: 07/24 - 07/29/94, San Diego, CA. Papers #2278-01 and #2278-12. Available at: http://www.spie.org/web/abstracts/2200/2278.html.
Castaldello L (ISOTEST Engineering SRL, I). Advanced material non destructive testing using high resolution dual energy tomography (DUALETO). Conference on Spacecraft Structures, Materials, and Mechanical Testing. March 1996. Available at: http://www.estec.esa.nl/conferences/96a02/prog.html.
A paper in the e-Journal of Nondestructive Testing.
Rau C, Somogyi A, Bytchkov A, Simionovici A. XANES microimaging and tomography. Available on the ESRF - The European Synchrotron Radiation Facility Web site

John P. Hageman, MS, CHP

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