Imaging tomography

Keywords radar radar imaging tomography high resolution synthetic aperture radar interferometry polarimetry Radon transform projection slice theorem backprojection. 

From the instrumental side, long term drifts of stages, sample holders or simply the sample in the imaged field of view (FOV) need to be avoided or compensated. This issue becomes especially crucial for longer term measurements and high resolution imaging (tomography). 

Nuclear magnetic resonance (NMR) is used for determining the eomponent diffusion coefficient from the relaxation times and T2, where is the relaxation time of magnetic polarization induced parallel to a magnetic field and T2 is the relaxation time of the polarization induced perpendicular to the direction of the magnetic field. On the other hand, NMR and ESR imaging (tomography) can be used to follow the chemical diffusion of a chemical component and therefore to determine... 

The classical computer tomography (CT), including the medical one, has already been demonstrated its efficiency in many practical applications. At the same time, the request of the all-round survey of the object, which is usually unattainable, makes it important to find alternative approaches with less rigid restrictions to the number of projections and accessible views for observation. In the last time, it was understood that one effective way to withstand the extreme lack of data is to introduce a priori knowledge based upon classical inverse theory (including Maximum Entropy Method (MEM)) of the solution of ill-posed problems [1-6]. As shown in [6] for objects with binary structure, the necessary number of projections to get the quality of image restoration compared to that of CT using multistep reconstruction (MSR) method did not exceed seven and eould be reduced even further. 

Fundamental of the Theory for Adaptive Image Reconstruction in X-Ray Tomography. 

Image reconstruction from projections is a basic process in computerized tomography (CT)... 

In this paper, discontinuities in cylindrical specimens were studied by ultrasonic reflection tomography. The aim was threefold. First, to localize discontinuities from circular C-scan images. Second, to reconstruct quantitative cross-sectional images from circular B-scan profiles (i.e., reflection tomograms). Finally, to obtain three-dimensional information (i.e., discontinuity location, dimension and type) by stacking these reflection tomograms in multiple planes, in the third dimension. 

Although the discontinuities may be seen clearly in the circular C-scan image, the image represents only a projection of discontinuities in a specific direction (i.e., a shadow of overlapping discontinuities). More information of the discontinuities according to location, dimension and type may be achieved by ultrasonic computed tomography (UCT) imaging. 

ASTM, Standard guide for Computed Tomography (CT) Imaging, 1995... 

Cohen, G. and F.A. DiBianca, The use of contrast-detail-dose evaluation of image quality in a computed tomographic scanner. Journal of Computer Assisted Tomography, 1979. 3(2) p. 189-195. 

Various computed tomography CT- scanners for industrial applications have been designed and constructed) They use as radiation sources X-ray tubes or gamma emitting radioisotopes and as detectors NaI(Tl)-scintillators for gamma rays and image intensifiers for X-rays. 

Lefebvre, J.P., Progress in linear inverse scattering imaging NDE application of Ultrasonic Reflection Tomography, in Inverse Problem in Engineering Mechanies, pp 371-375, (A.A.Balkema/ Rotterdam rookfleld, 1994). 

Figure Bl.17.10. Principles of 3D reconstruction methods, (a) Principle of single axis tomography a particle is projected from different angles to record correspondmg images (left panel) this is most easily realized in the case of a helical complex (right panel), (b) Principle of data processing and data merging to obtain a complete 3D structure from a set of projections.

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