FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

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RECENT MICROFUCUS X~RAY IMAGING APPLICATIONS
R-icha/id S. Pzagtot
Rldgz Incoipoiatzd
Tu.ck.zK, Go.on.Qia, U.S.A.
The advent of reliable, commercially-available high output microfocus
x-ray generating systems has enabled real time x-ray imaging to successfully
compete with film radiography. The advantages of a near point-source
of radiation in reducing x-ray image penumbral unsharpness are well known.
While tnicrofocus x-ray equipment has existed for more than four decades,
available microfocus x-ray equipment has been characterized by low x-ray
output, rendering the technique unsuitable for real time x-ray imaging.
Recently, advances in microfocus x-ray tubehead design have made available
microfocus x-ray equipment operating at energies up to 160kV with focal
spots on the order of 10 microns while at the same time producing x-ray
output intensities comparable to conventional x-ray generating systems.
The result is that microfocus x-ray imaging can be successfully applied
to a wide range of test projects ranging from thin, lightweight materials
to materials of substantial cross section and density up to the equivalent
of approximately 5/8" of steel.
The advantages of using microfocus imaging techniques are twofold. First,
image resolution is improved by orders of magnitude according to the
amount of geometric enlargement used. Resolutions on the order of 25 lint:
pair per millimeter are routinely achieved at 10X geometric enlargement
using a commercially-available imaging system having a resolving power of
only 2.5 line pair per millimeter. Second, image contrast is improved.
Thii» comes about through a reduction in the amount of test object scatter
radiation reaching the imaging system due to two factors: 1) the x-ray
illuminated area of the test object is reduced, thereby reducing the
amount of scatter generated, and 2) the test object is positioned away from
the image receptor reducing the scatter intensity and intercepted solid
angle.
The result is that high output microfocus x-ray imaging systems can
routinely produce equivalent penetrameter sensitivities on the order of
2-1T or even 1 — IT in some instances. The resulting high quality real time
video x-ray image may be processed using analog and/or digital image