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Speckle in ultrasound computerized reflection mode tomography
As part of an ongoing research programme to investigate how medical X- ray computed tomography (CT) can be used in non-destructive testing of polymeric materials, a series of peroxide cured, non-filled polyisoprene rubbers with different crosslink densities were investigated. It was found that a normal medical X-ray CT scanner, thanks to its excellent contrast resolution, is capable of detecting density variations, caused by crosslinking, which exceed 2-3 mg c m 3.
38523
Sakamoto, K.; Suzuki, Y.; Hirano, T.; Usami, K.
Improvement of spatial resolution of monochromatic x-ray CT using synchrotron radiation J a p a n e s e J o u r n a l of A p p l i e d Physics, Vol. 27, No. 1, pp. 127-132 (Jan. 1988) X-ray computed tomography (CT) using synchrotron radiation (SR) as an X-ray source potentially provides CT images of improved quality, since SR produces tunable, monochromatized and collimated X-ray beams of high flux density. CT images of small samples can be obtained rapidly with better spatial resolution and contrast as well as the spatial distribution of a specific element using the absorption edge. In this paper, a method for improving the spatial resolution of such a system is presented, involving the magnification of projection images using asymmetric diffraction. First, the modulation transfer function (MTF) of projection images of an X-ray test chart is measured in order to evaluate the spatial resolution. Next, using this method, CT images of several industrial materials are shown with spatial resolution of 15 30 micron and the usefulness of SR-CT with a high spatial resolution is demonstrated.
Kinney, J.H.; Johnson, Q,C., Saroyan, R.A., Nichols, M.C.; Bonse, U.; Nusshardt, R.; Pahl, R. 38516
Energy-modulated x-ray microtomography R e v i e w of Scientific I n s t r u m e n t s , Vol. 59, No. 1, pp. 196-197 (Jan.
1988) An instrument for computerized x-ray tomography is described which can provide three-dimensional examination of small samples (a few millimeters to a few centimeters) with resolution variable from 5 to 100 microns. Elemental and chemical-state distributions are obtained with high resolution by modulating the energy of the incident x-ray beam. An essential component is the monochromator designed and optimized for chemical microtomography. It has a narrow energy bandpass and a large degree of harmonic suppression, provides a uniform x-ray beam with small angle of divergence and is cooled in a way that eliminates thermal and vibrational instabilities. 38284
General Electric Co.
Automated X-ray inspection system for aircraft gas turbine blade - has part manipulator, programmable controller, movable platform, data acquisition system bar code reader and display E u r o p e a n P a t e n t No. 234,537 (2 Sep. 1987) 38093 Roehrlein, G.; Ermert, H, Speckle in ultrasound computerized reflection mode tomography A c o u s t i c a l I m a g i n g , Vol. 15. P r o c e e d i n g s of the 15th I n t e r n a t i o n a l S y m p o s i u m on A c o u s t i c a l I m a g i n g , Halifax, N o v a Scotia ( C a n a d a ) , 14-16 Jul. 1986. pp. 341-358. E d i t e d by H u g h W. Jones. P l e n u m Press, 704 pp. (1987). Macroscopic homogenous texture areas are represented in B-scan images not as a single homogenous grey-level, but as very "granular" areas with characteristic "granule-size". This phenomenon is commonly called, "speckle". Sevcral different approaches were investigated. They are extended in this paper to investigate speckle in ultrasound computerized reflection mode tomography (UCTR). UCTR can be explained as a numerical superposition of several B-scans of a cross sectional plane obtained from different angles. The superposition consists of a summation and an additional inverse filtering proccdurc, which is cquivalent to thc deconvolution in X-ray CT. UCTR has been investigated theoretically and has also been used for clinical in-vivo imaging of the female breast, muscles and thyroid gland. The results of first and second order statistics of speckle in the summation image are presented and measurements of the correlation-coefficients of two B-scans with different aspect-angles arc given. A special texture phantom is described which was used to verify the theory. In-rive images of testicles are used to demonstrate the speckle-reduction effect in UCTR images. 37896
Maier, P.; Pfister, G.; Stier, G.; Kegreiss, W.; Hehn, G.
Progress in neutron tomography for non-destructive testing N e u t r o n R a d i o g r a p h y , P r o c e e d i n g s of the S e c o n d W o r l d C o n f e r e n c e , Paris ( F r a n c e ) , 16-20 Jun. 1986. pp. 771-782. D. R e i d e l P u b l i s h i n g Company A neutron computer tomography scanner was developed and constructed using portable equipment and different neutron sources. Further studies will be done with cf-252 neutrons and fission neutrons from a nuclear reactor. Since each neutron source contains gamma radiation as well simultaneous neutron and a gamma computer tomograph (CT) images are possible I. In non-destructive material testing, fast neutrons can be used to examine thick metallic samples or to show small differences in the concentration of light nuclei. Several image reconstruction algorithms are available for samples with different size and material composition. A spatial resolution of 0.5 mm and a density resolution of about 5% could be achieved with the first CT images with fast neutrons. Neutron CT images show few artifacts compared to x-ray scans. Therefore the neutron CT technique can be used with advantage to examine strongly inhomogenous samples. Up to now the single beam technique has been used for all measurements. The Fanbeam technique is under study to reduce the measuring time.
NDT International October 1990
37715 Ellingson, W.A.; Sawicka, B.D.; Kriz, R.J.; Gronemeyer, S.; Ackerman, J.L,
X-ray tomography and nuclear magnetic resonance imaging applications for advanced ceramic materials A r g o n n e N a t i o n a l L a b o r a t o r y , A r g o n n e , Illinois ( U n i t e d States), C O N F - 870422-8, DE87-011534, 33 pp. (Feb. 1987) Advanced nondestructive evaluation methods are being developed to characterize ceramic materials and allow improvement of process technology. If one can determine porosity, map organic binder/ plasticizer distributions, through - volume density, and detect inclusions, machine operations can then be modified to enhance the reliability of ceramics. Two modes of X-ray tomographic imaging (advanced film tomography and computed tomography) are being developed to provide flaw detection and density profile mapping capability. Nuclear magnetic resonance imaging is being developed to determine porosity and map organic binder/plasticizer distribution. Results obtained with these methods will be presented. 37677
Siemens AG
Cooling system for computer tomography appts. - uses cooling channels for rotor carrying X/ray source and detector E u r o p e a n P a t e n t No. 255,964 (24 Jun. 1987) 37610
Streit, R.D.; Clark, G.A.; Brase, J.M.
Computed tomography for quantitative N D E M e c h a n i c a l E n g i n e e r i n g , Vol. 109, No. 9, pp. 56-64 (Sep. 1987) Computed tomography (C.T.) is a means of producing a three dimensional image by mathematically combining several two dimensional X ray attenuation distribution radiographic images taken from different angles. A computer performs the combination. Scintillating crystals, which convert X rays into visible light are commonly used in detectors as film response to X rays is exponential rather than linear. CT has been used to develop whole body scanners for medical science and many nondestructive evaluation uses are anticipated when this technique is more widely available. 37442
Quantum Diagnostics
Large area X/ray source particularly useful for tomography - has control grid electrode between co-extensive anode and cathode E u r o p e a n P a t e n t No. 202,489 (26 Nov. 1986) 37388
Flannery, B.P.; Deckman, H.W.; Roberge, W.G.; D'Amico,
K.L. Three-dimensional X-ray microtomography Science, Vol. 237, No. 4821, pp. 1439-1444 (18 Sep. 1987) The new technique of x-ray microtomography nondestructively generates three-dimensional maps of the x-ray attenuation coefficient inside small samples with approximately ! percent accuracy and with resolution approaching 1 micrometer. Spatially resolved elemental maps can be produced with synchrotron x-ray sources by scanning samples at energies just above and below characteristic atomic absorption edges. The system consists of a high-resolution imaging x-ray detector and high- speed algorithms for tomographic image reconstruction. The design and operation of the microtomography device are described, and tomographic images that illustrate its performance with both synchrotron and laboratory x-ray sources are presented. 37387
Wellington, S.L.; Vinegar, H.J.
X-ray computerized tomography J o u r n a l of P e t r o l e u m T e c h n o l o g y , Vol. 39, No. 8, pp. 885-898 ( A u g . 1987) Computerized tomography (CT) is a new radiological imaging technique that measures density and atomic composition inside opaque objects. A revolutionary advance in medical radiology since 1972, CT has only recently been applied in petrophysics and reservoir engineering. This paper discusses several petrophysical applications, including three- dimensional (3D) measurement of density and porosity 37380
Andersen, A.H.
Tomograpby transform and inverse in geometrical optics J o u r n a l of the O p t i c a l Society of A m e r i c a A , Vol. 4, No. 8, pp. 13851395 ( A u g . 1987) Geometrical optics is applied in a modeling of the forward-propagation process for transmission tomography with diffracting sources. The forward process is described mathematically as an optical tomography transform of an object function into a set of measured projection data representing line integrals • of the parameter function. A recursive scheme is devised for the inverse process of reconstruction of the object parameter function from its forward projections. Ultimately, a new computational scheme is presented for the fast and accurate reconstruction of the object function. Ray-tracing methods lead to a representation of the forward-propagation process as a system of linear equations. Simultaneous algebraic reconstruction methods are applied in the discretized inverse process. 37379
Miyoshi, S.; Tanirnoto, Y.; Uyama, K.; Sane, Y.
The evaluation of SCC defects of steel pipe using a high-energy x-ray CT scanner N u c l e a r E n g i n e e r i n g a n d D e s i g n , Vol. 102, No. 3, pp. 275-287 (Jul. 1987) The X-ray computed CT scanner, capable of producing sharp tomograms, was expected to become a practical and revolutional means in nondestructive
291
38523
Sakamoto, K.; Suzuki, Y.; Hirano, T.; Usami, K.
Improvement of spatial resolution of monochromatic x-ray CT using synchrotron radiation J a p a n e s e J o u r n a l of A p p l i e d Physics, Vol. 27, No. 1, pp. 127-132 (Jan. 1988) X-ray computed tomography (CT) using synchrotron radiation (SR) as an X-ray source potentially provides CT images of improved quality, since SR produces tunable, monochromatized and collimated X-ray beams of high flux density. CT images of small samples can be obtained rapidly with better spatial resolution and contrast as well as the spatial distribution of a specific element using the absorption edge. In this paper, a method for improving the spatial resolution of such a system is presented, involving the magnification of projection images using asymmetric diffraction. First, the modulation transfer function (MTF) of projection images of an X-ray test chart is measured in order to evaluate the spatial resolution. Next, using this method, CT images of several industrial materials are shown with spatial resolution of 15 30 micron and the usefulness of SR-CT with a high spatial resolution is demonstrated.
Kinney, J.H.; Johnson, Q,C., Saroyan, R.A., Nichols, M.C.; Bonse, U.; Nusshardt, R.; Pahl, R. 38516
Energy-modulated x-ray microtomography R e v i e w of Scientific I n s t r u m e n t s , Vol. 59, No. 1, pp. 196-197 (Jan.
1988) An instrument for computerized x-ray tomography is described which can provide three-dimensional examination of small samples (a few millimeters to a few centimeters) with resolution variable from 5 to 100 microns. Elemental and chemical-state distributions are obtained with high resolution by modulating the energy of the incident x-ray beam. An essential component is the monochromator designed and optimized for chemical microtomography. It has a narrow energy bandpass and a large degree of harmonic suppression, provides a uniform x-ray beam with small angle of divergence and is cooled in a way that eliminates thermal and vibrational instabilities. 38284
General Electric Co.
Automated X-ray inspection system for aircraft gas turbine blade - has part manipulator, programmable controller, movable platform, data acquisition system bar code reader and display E u r o p e a n P a t e n t No. 234,537 (2 Sep. 1987) 38093 Roehrlein, G.; Ermert, H, Speckle in ultrasound computerized reflection mode tomography A c o u s t i c a l I m a g i n g , Vol. 15. P r o c e e d i n g s of the 15th I n t e r n a t i o n a l S y m p o s i u m on A c o u s t i c a l I m a g i n g , Halifax, N o v a Scotia ( C a n a d a ) , 14-16 Jul. 1986. pp. 341-358. E d i t e d by H u g h W. Jones. P l e n u m Press, 704 pp. (1987). Macroscopic homogenous texture areas are represented in B-scan images not as a single homogenous grey-level, but as very "granular" areas with characteristic "granule-size". This phenomenon is commonly called, "speckle". Sevcral different approaches were investigated. They are extended in this paper to investigate speckle in ultrasound computerized reflection mode tomography (UCTR). UCTR can be explained as a numerical superposition of several B-scans of a cross sectional plane obtained from different angles. The superposition consists of a summation and an additional inverse filtering proccdurc, which is cquivalent to thc deconvolution in X-ray CT. UCTR has been investigated theoretically and has also been used for clinical in-vivo imaging of the female breast, muscles and thyroid gland. The results of first and second order statistics of speckle in the summation image are presented and measurements of the correlation-coefficients of two B-scans with different aspect-angles arc given. A special texture phantom is described which was used to verify the theory. In-rive images of testicles are used to demonstrate the speckle-reduction effect in UCTR images. 37896
Maier, P.; Pfister, G.; Stier, G.; Kegreiss, W.; Hehn, G.
Progress in neutron tomography for non-destructive testing N e u t r o n R a d i o g r a p h y , P r o c e e d i n g s of the S e c o n d W o r l d C o n f e r e n c e , Paris ( F r a n c e ) , 16-20 Jun. 1986. pp. 771-782. D. R e i d e l P u b l i s h i n g Company A neutron computer tomography scanner was developed and constructed using portable equipment and different neutron sources. Further studies will be done with cf-252 neutrons and fission neutrons from a nuclear reactor. Since each neutron source contains gamma radiation as well simultaneous neutron and a gamma computer tomograph (CT) images are possible I. In non-destructive material testing, fast neutrons can be used to examine thick metallic samples or to show small differences in the concentration of light nuclei. Several image reconstruction algorithms are available for samples with different size and material composition. A spatial resolution of 0.5 mm and a density resolution of about 5% could be achieved with the first CT images with fast neutrons. Neutron CT images show few artifacts compared to x-ray scans. Therefore the neutron CT technique can be used with advantage to examine strongly inhomogenous samples. Up to now the single beam technique has been used for all measurements. The Fanbeam technique is under study to reduce the measuring time.
NDT International October 1990
37715 Ellingson, W.A.; Sawicka, B.D.; Kriz, R.J.; Gronemeyer, S.; Ackerman, J.L,
X-ray tomography and nuclear magnetic resonance imaging applications for advanced ceramic materials A r g o n n e N a t i o n a l L a b o r a t o r y , A r g o n n e , Illinois ( U n i t e d States), C O N F - 870422-8, DE87-011534, 33 pp. (Feb. 1987) Advanced nondestructive evaluation methods are being developed to characterize ceramic materials and allow improvement of process technology. If one can determine porosity, map organic binder/ plasticizer distributions, through - volume density, and detect inclusions, machine operations can then be modified to enhance the reliability of ceramics. Two modes of X-ray tomographic imaging (advanced film tomography and computed tomography) are being developed to provide flaw detection and density profile mapping capability. Nuclear magnetic resonance imaging is being developed to determine porosity and map organic binder/plasticizer distribution. Results obtained with these methods will be presented. 37677
Siemens AG
Cooling system for computer tomography appts. - uses cooling channels for rotor carrying X/ray source and detector E u r o p e a n P a t e n t No. 255,964 (24 Jun. 1987) 37610
Streit, R.D.; Clark, G.A.; Brase, J.M.
Computed tomography for quantitative N D E M e c h a n i c a l E n g i n e e r i n g , Vol. 109, No. 9, pp. 56-64 (Sep. 1987) Computed tomography (C.T.) is a means of producing a three dimensional image by mathematically combining several two dimensional X ray attenuation distribution radiographic images taken from different angles. A computer performs the combination. Scintillating crystals, which convert X rays into visible light are commonly used in detectors as film response to X rays is exponential rather than linear. CT has been used to develop whole body scanners for medical science and many nondestructive evaluation uses are anticipated when this technique is more widely available. 37442
Quantum Diagnostics
Large area X/ray source particularly useful for tomography - has control grid electrode between co-extensive anode and cathode E u r o p e a n P a t e n t No. 202,489 (26 Nov. 1986) 37388
Flannery, B.P.; Deckman, H.W.; Roberge, W.G.; D'Amico,
K.L. Three-dimensional X-ray microtomography Science, Vol. 237, No. 4821, pp. 1439-1444 (18 Sep. 1987) The new technique of x-ray microtomography nondestructively generates three-dimensional maps of the x-ray attenuation coefficient inside small samples with approximately ! percent accuracy and with resolution approaching 1 micrometer. Spatially resolved elemental maps can be produced with synchrotron x-ray sources by scanning samples at energies just above and below characteristic atomic absorption edges. The system consists of a high-resolution imaging x-ray detector and high- speed algorithms for tomographic image reconstruction. The design and operation of the microtomography device are described, and tomographic images that illustrate its performance with both synchrotron and laboratory x-ray sources are presented. 37387
Wellington, S.L.; Vinegar, H.J.
X-ray computerized tomography J o u r n a l of P e t r o l e u m T e c h n o l o g y , Vol. 39, No. 8, pp. 885-898 ( A u g . 1987) Computerized tomography (CT) is a new radiological imaging technique that measures density and atomic composition inside opaque objects. A revolutionary advance in medical radiology since 1972, CT has only recently been applied in petrophysics and reservoir engineering. This paper discusses several petrophysical applications, including three- dimensional (3D) measurement of density and porosity 37380
Andersen, A.H.
Tomograpby transform and inverse in geometrical optics J o u r n a l of the O p t i c a l Society of A m e r i c a A , Vol. 4, No. 8, pp. 13851395 ( A u g . 1987) Geometrical optics is applied in a modeling of the forward-propagation process for transmission tomography with diffracting sources. The forward process is described mathematically as an optical tomography transform of an object function into a set of measured projection data representing line integrals • of the parameter function. A recursive scheme is devised for the inverse process of reconstruction of the object parameter function from its forward projections. Ultimately, a new computational scheme is presented for the fast and accurate reconstruction of the object function. Ray-tracing methods lead to a representation of the forward-propagation process as a system of linear equations. Simultaneous algebraic reconstruction methods are applied in the discretized inverse process. 37379
Miyoshi, S.; Tanirnoto, Y.; Uyama, K.; Sane, Y.
The evaluation of SCC defects of steel pipe using a high-energy x-ray CT scanner N u c l e a r E n g i n e e r i n g a n d D e s i g n , Vol. 102, No. 3, pp. 275-287 (Jul. 1987) The X-ray computed CT scanner, capable of producing sharp tomograms, was expected to become a practical and revolutional means in nondestructive
291