It is now possible for large volumes of synchrotron- radiation-generated micro-tomography data to be produced at gigabyte-per-minute rates, especially when using currently available CCD cameras at a high-brightness source, such as the Advanced Photon Source (APS). Recent improvements in the speed of our detectors and stages, combined with increased photon flux supplied by a newly installed double multilayer monochromator, allow us to achieve these data rates on a bending magnet beamline. Previously, most x-ray microtomography experiments have produced data at comparatively lower rates, and often the data were analyzed after the experiment. The time needed to generate complete data sets meant putting off analysis to the completion of a run, thus preventing the user from evaluating the usefulness of a data set and consequently impairing decision making during data acquisition as to how to proceed. Thus, the ability to provide to a tomography user a fully reconstructed data set in few minutes is one of the major problems to be solved when dealing with high-throughput x- ray tomography. This is due to the complexity of the data analysis that involves data preprocessing, sinogram generation, 3D reconstruction, and rendering. At the APS, we have developed systems and techniques to address this issue. We present a method that uses a cluster-based, parallel- computing system based on the Message Passing Interface (MPI) standard. Among the advantages of this approach are the portability, ease-of-use, and low cost of the system. The combination of high-speed, online analysis with high- throughput acquisition allows us to acquire and reconstruct a 512x512x512-voxel sample with a few microns resolution in less than ten minutes.

One major goal in x-ray tomography is to increase the resolution in space and time. For the methods with high temporal resolution we will present pink beam imaging and tomography. Experiments were realised at the ESRF undulator beamline ID22 with hard x-rays in the range from 11 keV to 20 keV. For the tomographic scans the exposure time per image was reduced by one to two orders of magnitude to less than 50 ms per image. The obtained image quality was comparable to that done with monochromatic beam. Further time reducing for a tomographic scan is possible with an improved acquiring and control system. The goal in the future is to realise tomographic scans within a minute with micrometer resolution. In order to achieve in the hard x-ray range sub-micrometer resolution we will show first results of x-ray magnified tomography. Different lens systems are available for this purpose. We obtained with aluminium parabolic compound refractive lenses a resolution of 1 micrometers and expect to overcome this limit hand in hand with the improvement of lens technology.

Parabolic compound refractive lenses (PCRLs) are high quality imaging optics for hard x-rays that can be used as an objective lens in a new type of hard x-ray full field microscope. Using an aluminium PCRL, this new type of microscope has been shown to have a resolution of 350 nm. Further improvement of the resolution down to 50 nm can be expected using beryllium as a lens material. The large depth of field (several mm) of the microscope results in sharp projection images for samples that fit into the field of view of about 300 micrometers. This allows to combine magnified imaging with tomographic techniques. First results of magnified microtomography are shown. Contrast formation in the microscope and the consequences for tomographic reconstruction are discussed. An outlook on further developments is given.

Microtomography using synchrotron radiation became a valuable tool for the noninvasive, 3-dim. investigation of samples in fields like medicine, biology and material science. Attenuation- and phase-contrast techniques were optimized at beamline BW2 using photon energies in the range of 8 to 24 keV. In order to extend this method to larger samples, resp. to specimen consisting of elements with higher absorption the apparatus was set up at the high energy beamline BW5 to apply attenuation contrast microtomography using photon energies in the range of 60 to 110 keV. Furthermore different scanning techniques were developed and applied to larger samples up to 22 mm in diameter. The experimental setup originally developed at the University of Dortmund, Germany and the improvements made at HASYLAB to provide for a user experiment for attenuation-contrast microtomography will be described. Several examples will demonstrate the practical application of the current system as a user experiment for performing continuous tomographical scans.

At the Material Science Beamline 4S of the Swiss Light Source (SLS), the X-ray Tomographic Microscopy (XTM) facility is entering its final construction phase. A high performance detector based on a scintillating screen optically coupled to a CCD camera has been developed and tested. MTF-responses of the detector system show spatial resolution down to the micrometer level. A second detector, which will provide a quantum jump in term of spatial resolution and efficiency, has been successfully simulated and will be integrated in the current device soon. A user- friendly graphical interface gives access to the main measurements parameters needed for a complete tomographic scan in absorption as well as in phase-contrast mode. The new instrumentation shall be used for the analysis of the physical structure and chemical composition of technical materials and biological samples, e.g. enabling non- destructive testing during the development of modern composite materials, or enabling pseudo-dynamic testing of bone samples to establish structure-function relationships in simulated osteoporosis.

A tomography beamline has been built recently at the LSU CAMD synchrotron. The instrument consists of a Linux/LabVIEW-controlled CCD and Macintosh/LabVIEW controlled positioning stages. The two computers communicate via LabVIEW/TCP/IP. A Macintosh G4/Linux cluster has been installed for the purpose of on-site reconstruction. Instrument alignment and reconstruction programs are written in LabView, Matlab, and IDL. Applications to date are many. The blending of flame retardants (brominated aromatics, phosphates, and antimony oxide) in high-impact polystyrene is being studied with tomography; this work complements solid-state 81Br NMR. Also, several biological samples are to be studied as part of a multi-investigator project on biological visualization and computational studies. This project gives the tomography workers close access to an ImmersaDesk R2 and other computational resources.

An image intensifier based computed tomography scanner and a tube source of x-rays are used to obtain the images of small objects, plastics, wood and soft materials in order to know the interior properties of the material. A new method is developed to estimate the degree of monochromacy, total solid angle, efficiency and geometrical effects of the measuring system and the way to produce monoenergetic radiation. The flux emitted by the x-ray tube is filtered using the appropriate filters at the chosen optimum energy and reasonable monochromacy is achieved and the images are acceptably distinct. Much attention has been focused on the imaging of small objects of weakly attenuating materials at optimum value. At optimum value it is possible to calculate the three-dimensional representation of inner and outer surfaces of the object. The image contrast between soft materials could be significantly enhanced by optimal selection of the energy of the x-rays by Monte Carlo methods. The imaging system is compact, reasonably economic, has a good contrast resolution, simple operation and routine availability and explores the use of optimizing tomography for various applications.

Image quality of phase-contrast x-ray computed tomogram was evaluated by comparing tomograms obtained by using triple Laue-case x-ray interferometers with a thin or a thick crystal wafer. It was confirmed that the spatial resolution was improved when the wafer is thinned. A simulation study by means of the Takagi-Taupin equation was also carried out for theoretical understanding. According to the wavefront modulation transfer function calculated for Laue-case diffraction, it is suggested that using an interferometer with al thin wafer tends to improve image quality. However, a new problem is pointed out that the accuracy in quantitative measurement of high-frequency phase modulation is not secured even when the wafer is thinned.

When used in microimaging, hard x rays from third-generation synchrotron radiation (SR) sources inevitably generate noninterferometric or in-line phase contrast. It is formed by the propagation of a distorted x-ray wavefront after the sample. In this paper, we discuss phase contrast and its properties in two altogether different experimental modes. First, in edge-enhanced microtomography, we show by phase- propagation simulations that local tomography is possible without special effort. The second part of the paper discusses phase contrast and phase artifacts in magnified x- ray imaging and tomography using refractive lenses. Here, the phase effects degrade resolution to a considerable extent. This part of the paper contains experimental results from the ESRF beamline ID 22 in the photon energy range around 20 keV that are compared to simulated images and to experimental results from conventional high-resolution microtomography. The experimental results show that coherence-degrading devices can reduce but not completely eliminate phase effects, and recent microtomography data gathered with an x-ray microscope still cannot beat conventional state-of-the-art high-resolution microtomography with micrometer resolution.

The leading X-ray computed microtomographic imaging facilities can now provide 1024³ voxel images of rock and other porous media samples at a voxel resolution of under 5 microns. Such data sets are extremely rich in information, and overwhelming in size; a 1024³ data set corresponds to a gigabyte of character data. Automated computer analysis is necessary in order to extract quantitative information from such images. In this paper we discuss automated extraction of geometrical features using computerized image analysis. Typical algorithms required include segmentation to identify the material type of each voxel in the image; medial axis reduction of objects in the image to provide a skeleton enabling efficient searching and geometrical characterization as well as a network for the application of graph theoretic tools; feature extraction; measurement of length, cross sectional area and volume; and stochastic characterization of measured properties. With current memory limitations in desktop workstations, data sets beyond 512³ voxels in size require parallelization of the algorithms.

In industrial Radiogram, scatter noise, uneven distribution of X ray and other noises directly affect image quality. Among them scatter noise is the major part. Many researchers have employed various methods to make model to get accurate estimation of scatter distribution. But these methods and models are difficult to perform well in other different situations. In this paper we propose a method integrated physical and mathematical processing to solve this problem perfectly. Based on the analysis of the scatter distribution in X-ray image and the contribution of the low frequency noise to image deterioration, in this paper a new integrated method is used to correct these effects as follows. First using the optical theory we deduce the expression of scatter distribution, which is proved to be subject to Gaussian distribution. The expression provides a theoretic basis for removing the scatter with physical method, by which we get remarkable quality-improved X-ray images. Then multi- resolution analysis is employed to decompose the images acquired on the above theoretic basis, and it makes the processing of different frequency components of the X-ray images become easy. In our experiment, the results are satisfied. The method not only avoids making different models under different experiment conditions universally, but also provides a promising way for real-time X-ray image correction and detection.

Laboratory instruments for high-resolution microtomography (micro-CT) are based on the object irradiation by the x-ray sources with spot size in the micron range. The microfocus laboratory x-ray sources produce x-ray radiation by interaction of electron beam with a metal target. Spot size in this case is defined by focusing of electron beam and limited by melting point of the metal target. That means the improvement in spot size and spatial resolution can be done only against power of the x-ray sources. For most effective collection of x-ray flux from the low-power sources two- dimensional detectors should be used for images acquisition. By this reason the x-ray geometry in the high-resolution micro-CT instruments corresponding to cone-beam acquisition with relatively big divergent angle. In such geometry all conventional fan-beam CT-reconstruction algorithms may produce significant geometrical distortions. We developed and tested reconstruction software packages for different algorithms: fan-beam, cone-beam (Feldkamp) and spiral (helical) scans using two-dimensional detectors. All algorithms were applied to different simulations as well as to the real datasets from the commercial micro-CT instruments. From the results of testing a number of strong and weak points at different approaches have been found.

The inadequacies of current analytical models for grain growth are thought to arise in part from their mean-field nature: they ignore the presence of correlations in the sizes of neighboring grains induced by the process of grain growth itself. Although grain-size correlations have been identified in microstructures generated by computer simulations of grain growth, no comparable evidence has been obtained from real samples - primarily because of the experimental difficulties associated with evaluating this inherently three-dimensional property. Using absorption- contrast x-ray microtomography, we have attempted to characterize the network of grain boundaries in polycrystalline samples of Al doped with up to 3 at.% Sn. In principle, since the tin atoms segregate to the grain boundaries, it should be possible to determine the size and relative position of each grain from a three-dimensional reconstruction of the Sn distribution, from which the desired correlation function could be calculated directly. However, the grain boundaries in Al-Sn are not uniformly decorated with tin, which presents a formidable challenge to quantifying the microstructural properties of such samples. Significant progress toward overcoming this problem has been achieved by applying a constrained phase-field grain-growth algorithm to an approximate microstructure gleaned from the tomographic contrast data.

A double walled copper vessel, 32 cc in volume, was fabricated for micro-CT scanning tissue specimens maintained at cryogenic temperature. The space between the two nested vessels was evacuated and in two opposing sides of the vessel the copper has been replaced by beryllium foil. Nitrogen gas, boiling off liquid nitrogen, is injected continuously into the top of the chamber during the scanning process. Just prior to venting from the vessel the gas is heated and directed through a narrow gap over the outside of the beryllium windows so as to maintain the beryllium windows frost free. A temperature detector within the chamber is used to control the rate of inflow of the nitrogen gas. The frozen specimen is attached to a small horizontal platform on top of a vertical stainless steel pin which exits the base of the vessel through a closely fitting hole and is attached to the computer-controlled rotating stage under the vessel. The vessel and rotation-stage assembly is mounted on a computer-controlled horizontal translation stage which can move the specimen out of the x- ray beam, from time to time, for x-ray beam calibration purposes. The purpose of this arrangement is to permit scanning of specimens that: 1) either cannot be fixed (e.g., with formalin) because of biomolecular analyses which are incompatible with prior fixation, or 2) are snap-frozen during a transient process, such as the accumulation and/or washout of radiopaque indicators distributed in microvascular or extravascular compartments, which lasts only seconds and hence is too fast for normal micro-CT methods to capture.

Synchrotron radiation and x-ray microtomography based on absorption contrast (performed at HASYLAB at DESY/Hamburg and BAM/Berlin) have been used for imaging of temporal bones and various internal components in situ at spatial resolution down to 7 micrometers with potential enhancement into the submicron range. Due to the volume imaging approach, several hidden structures (e.g., intra-ossicular channels) were revealed. Using several 3D-image processing techniques all data have been segmented into objects (e.g., bony ossicles, ligaments, fluids, air spaces) and subsequently transformed into vectorized data models. Because they are based on the original voxel resolution their content of vector primitives (e.g., polygons) is huge compared to recent models. Therefore they became polygon-reduced to fit into current computation limitations. So far individual data models of the entire hearing apparatus from tympanic membrane to cochlea out of intact specimen, including separate models of ossicles, ligaments and other components have been obtained, provided, in interchangeable data formats (e.g. vector-based: IGES, STL, VRML) and introduced into FEA for modeling of acousto-mechanic transfer characteristics of the middle ear. Their pseudo and real 3D- visualizations (rendering, autosteroscopic display, enlarged solid models) allow easy understanding of the anatomy and pathology of the human hearing organ and may support patient and student education in the field of otology and audiology.

By employing the natural absorption contrast of organic matter in water at 0.5 keV photon energy, X-ray microcopy has resolved 30 nm structures in animal cells. To protect the cells from radiation damage caused by x-rays, imaging of the samples was performed at cryogenic temperatures, which makes it possible to take multiple images of a single cell. Due to the small numerical aperture of zone plates, X-ray objectives have a depth of focus on the order of several microns. By treating the X-ray microscopic images as projections of the sample absorption, computed tomography (CT) can be performed. Since cryogenic biological samples are resistant to radiation damage, it is possible to reconstruct frozen-hydrated cells imaged with a full-field X-ray microscope. This approach is used to obtain three- dimensional information about the location of specific proteins in cells. To localize proteins in cells, immunolabelling with strongly X-ray absorbing nanoparticles was performed. With the new tomography apparatus developed for the X-ray microscope XM-1 installed at the ALS, we have performed tomography of immunolabelled frozen-hydrated cells to detect protein distributions in all three dimensions inside of cells. As a first example, the distribution of the nuclear protein, male specific lethal 1 (MSL-1) in the Drosophila melanogaster cell was studied.

We have applied projection X-ray microscope for three- dimensional (3D) structure analysis by means of cone-beam computed tomography. The projection images of small insect, Omiscus Porcellio, were recorded in every 1 degree for whole direction (360 degree) with a stepping motor controlled sample rotator. The images were recorded with cooled CCD camera (HAMAMATSU C4880) which detect X-ray directly. The 3D image was reconstructed from cone-beam projections using back-projection algorithm. The resolution of the reconstructed 3D image (256 x 256 x 256 pixels) was about 20 micrometers . The digestive organs were clearly visualized in 3D.

The tomography beamline X27A at the National Synchrotron Light Source at Brookhaven National Laboratory was used to study the destructive spruce bark beetle, Dendroctonus rufipennis (Kirby). The x-ray computed microtomography (CMT) instrument is equipped with filtered white x-ray beam with energy of around 18 keV and, alternatively, a monochromatic beam with energy of around 4 to 14 keV and a 1% band pass. The instrument records microtomographic volumes with 10⁸ to 10⁹ voxels and spatial resolution down to about 3- micron voxels. Three-dimensional image reconstruction provides density and spatial information about solid heterogeneous forms. We have demonstrated that CMT images can be used to nondestructively characterize the internal structure of the beetle - symbiont fungal complex as part of an effort to understand the role of these organisms in the devastation of spruce forests throughout south-central Alaska.

Microtomography based on synchrotron radiation sources is a unique technique for the 3D characterization of different materials with a spatial resolution down to about 1 micrometers . The interface between implant materials (metals, ceramics and polymers) and biological matter is nondestructively accessible, i.e. without preparation artifacts. Since the materials exhibit different x-ray absorption, it can become impossible to visualize implant material and tissue, simultaneously. Here, we show that coating of polymer implants, which are invisible in bone tissue, does not only improve the interfacial properties but also allows the imaging of the interface in detail. Titanium implants, on the other hand, absorb the x-rays stronger than bone tissue. The difference, however, is small enough to quantify the bone formation near interface. Another advantage of microtomography with respect to classical histology is the capability to examine samples in a hydrated state. We demonstrate that ceramic hollow spheres can be imaged before sintering and fibroblasts marked by OsO₄ are visible on polymer textiles. Consequently, scaffolds of different materials designed for tissue engineering and implant coatings can be optimized on the basis of the tomograms.

Small laboratory animals (mice and rats) are widely used in development of drugs and treatments. To recognize the internal changes in the very early stage inside the body of alive animal, high-resolution micro-CT scanner has been developed. Initial changes in the bone structure can be found as features in the size range of 10 microns. By this reason a voxel size for reconstructed cross sections has been chosen as small as 10 microns. Full animal body may be up to 80 mm in diameter and up to 200 mm in length. By this reason the reconstructed cross section format selected as 8000 x 8000 pixels (float-point). A new 2D detection system with multibeam geometry produces dataset for reconstruction of hundreds of cross sections after one scan. Object illuminated by microfocus sealed x-ray source with 5 microns spot size. Continuously variable energy in the range of 20- 100 kV and energy filters allows estimate material composition like in DEXA systems. Direct streaming of the projection data to the disk reduce irradiation dose to the animal under scanning. Software package can create realistic 3D images from the set of reconstructed cross sections and calculate internal morphological parameters.

Many bones within the axial and appendicular skeleton are subjected to repetitive, cyclic loading during the course of ordinary daily activities. If this repetitive loading is of sufficient magnitude or duration, fatigue failure of the bone tissue may result. In clinical orthopedics, trabecular fatigue fractures are observed as compressive stress fractures in the proximal femur, vertebrae, calcaneus and tibia, and are often preceded by buckling and bending of microstructural elements. However, the relative importance of bone density and architecture in the aetiology of these fractures is poorly understood. The aim of the study was to investigate failure mechanisms of 3D trabecular bone using micro-computed tomography (mCT). Because of its nondestructive nature, mCT represents an ideal approach for performing not only static measurements of bone architecture but also dynamic measurements of failure initiation and propagation as well as damage accumulation. For the purpose of the study, a novel micro-compression device was devised to measure loaded trabecular bone specimens directly in a micro-tomographic system. A 3D snapshot of the structure under load was taken for each load step in the mCT providing 34 mm nominal resolution. An integrated mini-button load cell in the compression device combined with the displacement computed directly from the mCT scout view was used to record the load-displacement curve. From the series of 3D images, failure of the trabecular architecture could be observed, and in a rod-like type of architecture it could be described by an initial buckling and bending of structural elements followed by a collapse of the overloaded trabeculae. A computational method was developed to quantify individual trabecular strains during failure. The four main steps of the algorithm were (i) sequential image alignment, (ii) identification of landmarks (trabecular nodes), (iii) determine nodal connectivity, and (iv) to compute the nodal displacements and local strains. It was found that for a 1% global strain, the localized strains between nodes were as high as eight times and six times the global compressive and tensile strains, respectively. This provided further evidence for a band-like, local failure of trabecular bone. In conclusion, micro-compression in combination with 3D mCT allows visualization and quantification of failure initiation and propagation and monitoring of damage accumulation in a nondestructive way. We expect these findings to improve our understanding of the relative importance of density, architecture and load in the aetiology of spontaneous fractures of the hip and the spine. Eventually, this improved understanding may lead to more successful approaches to the prevention of age-related fractures.

Some very small parts from regular cellular (spherical) metals were investigated in a strength test, which was done inside the (mu) CT machine with resolutions down to 5 micrometers . The aim was to inspect the behavior of the walls of cellular metals under load, and to find out how the buckling or breaking starts. The results are needed for theoretical calculations, which will be used to predict the behavior of large structures of these materials. Also the pore size and pore size distribution for cellular metals is calculated and a method to separate walls and nodes is presented. CT insights of cellular metals as well as investigations of data by means of image processing is shown.

The 3D microfocus x-ray tomography is one technique of nondestructive testing used in the most different areas of science and technology, given its capacity to generate clean images (practically free of the unsharpness effect) and high resolution reconstructions. The unsharpness effect minimization and space resolution improvement are consequences of the focal spot size reduction in the x-ray microfocus tube to dimensions smaller than 50 micrometers . A problem normally found in the industrial area is the characterization of system parts with similar complex architectures to the bone structures. In the medicine, these structures are quantified through morphologic and topologic parameters such as: volume to volume ratio, area to volume ratio, connectivity, anisotropy and derived parameters, all obtained currently by means of the tomography system and in an automated way. In this work, the results of the complex object characterization are presented (ceramic filter) using 3D tomography system for parameter extraction.

We present recent results of fluorescence tomography experiments obtained on a variety of samples originating from the fields of Mineralogy, Space Sciences or Botany. The ID22 hard X-ray microanalysis beamline of the ESRF was used in scanning beam mode to record fluorescence spectra in pencil-beam collection mode for energies of 14 to 22.5 keV and micron-sized beamspots. Trace element concentrations of a few hundred ppm were successfully imaged in inhomogenous samples of less than 500 microns and resolutions up to 2 microns.

Sample preparation for element analysis of many biological tissues is difficult to achieve and prone to introduce contamination. Using x-ray fluorescence element microtomography (XFEMT) the element distribution on a virtual section across the sample can be determined with a resolution in the micrometer range. Fluorescence microtomograms of two plant samples are shown, demonstrating the possibility to map physiologically relevant ions, trace elements, and heavy metal pollutants at the cellular level. Attenuation effects inside the plant are corrected by a self-consistent tomographic reconstruction technique.

In chemistry, x-ray absorption near-edge spectroscopy (XANES) is a well-known and established technique. By scanning the x-ray energy in the vicinity (50-100 eV) of the absorption edge of an element, information can be obtained about the oxidation state of the probed atoms. The (conventional) technique mainly employed until now applies for homogeneous, specifically prepared flat samples where the measured signal can be considered as the average over the whole irradiated volume. This restriction for samples is partially released when the XANES method is combined with imaging techniques. Two-D resolved data is acquired using area detectors or by scanning with a focused beam. X-ray absorption tomography is a method of choice for investigating the 3D structure of objects and its dual energy version is used for getting information about the 3D distribution of a given element within the sample. Although the combination of XANES and tomography seems to be a natural extension of dual-energy tomography, in practice several experimental problems have to be overcome in order to obtain useable data. In the following we describe the results of XANES imaging and tomography obtained measuring a phantom sample of pure molybdenum compounds using a FreLoN 2000 camera system at the ESRF undulator beamline ID22. This system allowed making volume resolved distinctions between different oxidation states with spatial resolution in the micrometer range.

Adhesive bonded composites used in naval, aerospace, and automotive technologies require routine nondestructive testing (NDT) to detect flaws and other integrity-reducing anomalies such as porosity, kissing disbonds, and delaminations. We have developed an x-ray radiography/CT system with fast scanning times based on high resolution, high efficiency scintillators coupled to a 1024 x 1024 pixel CCD via a fiberoptic taper. Typical CT systems for NDT use a fan beam x-ray source and a linear array of detectors, with scan times on the order of 10 hours depending on the desired resolution. The prototype CCD-based volumetric imaging system described here is capable of reducing this scan time to less than 1 hour while significantly improving resolution. Additionally, the system is capable of both CT and standard radiographic imaging. We have integrated two different scintillators in the prototype system. One is a structured CsI(Tl) screen, and the other is a new, pixelated, transparent optical ceramic (TOC) scintillator. This unique TOC has a density of 9.5 g/cm³ and a peak emission of 610 nm, particularly suitable for Si readouts. We present here the system design and preliminary results of radiographic imaging and volumetric CT reconstruction.

Nondestructive information from the internal structure of plastic and composites in natural or adjustable environmental conditions can be obtained by transmission x- ray microscopy. Combination of x-ray microscopy technique with tomographical reconstruction allows getting three- dimensional information about the internal microstructure. A desktop x-ray microscopy-microtomograph SkyScan-1072 has been used in different application areas including plastic, epoxy and metal composite materials and products. The x-ray magnification ranges between 15 and 180. Reconstruction time is near 10 sec per cross section. One of most important application area is composite material where one wants to investigate the 3D structure and reaction to external influences. The system allows obtaining transmission image through the object's materials and to reconstruct nondestructively any cross section or complete internal 3D structure. The sample can be loaded in situ to investigate the reaction of matrix and enforcing structures to external strain. Liquid's absorption and transport through porous materials can be shown directly in three-dimensions. Small details up to 2-3 micrometer in size can be visualized inside the specimen. Software included powerful image processing package to calculate the numerical characteristics of the object's internal microstructure and to create realistic 3D visualization with possibilities of rotation and cutting of reconstructed object into the screen as well as flight simulator for fly through the object microstructure. Microscopical 3D visualization without vacuum and coatings allows displaying the natural specimen structure as well as examine its behavior under external influences (loading, chemical reactions, interaction with other solids, liquids, gases, etc.).

An x-ray microtomograph (or micro-CT) is an instrument for nondestructive 3-dimensional reconstruction of the object's internal microstructure without physical cut or time consuming specimen preparation. By using modern technology in x-ray sources and detectors several micro-CT systems were created as a simply usable desktop instrument. First micro- CT system is a laboratory instrument, giving true spatial resolution over ten million times more detailed (in the term of volume parts) than the medical CT-scanners. The instrument contains a sealed microfocus x-ray source, a cooled x-ray digital CCD-camera and a Dual Pentium computer for system control and 3D reconstructions running under Windows 2000. The instrument includes possibilities for image analysis in the nondestructively reconstructed internal microstructure and realistic 3D visualization. During scanning, objects are displaced in normal environment conditions, without vacuum or preparation. Another micro-CT scanner is a low-cost portable instrument, which can be connected to any external Pentium-based PC. Third instrument - microlaminograph - can create nondestructive slicing in any place of big planar objects (electronic assemblies, PCBs, etc.). This system uses principles of tomosynthesis from incomplete dataset for slicing in internal object's layers. The main application areas for micro-CT and microlaminography systems are biomedical research, material sciences, electronic components, etc.

A high spatial resolution x-ray CT system was developed at SPrng-8. The experiments were performed at the in-vacuum type undulator beamline BL47XU. A Si (111) double crystal monochromator is cooled with liquid nitrogen. A high precision rotation stage was used for sample rotation stage. Transmitted images were measured with an image detector. As the results of performance tests, it is considered that the spatial resolution of at least 1 micrometers was achieved with this system. The three-dimensional textures of eutectic alloy and a fossil of diatom were observed with this system.

Fluorescent x-ray CT (FXCT) with synchrotron radiation (SR) is being developed to detect the very low concentration of specific elements. The endogenous iodine of the human thyroid and the non-radioactive iodine labeled BMIPP in myocardium were imaged by FXCT. FXCT system consists of a silicon (111) double crystal monochromator, an x-ray slit, a scanning table for object positioning, a fluorescent x-ray detector, and a transmission x-ray detector. Monochromatic x-ray with 37 keV energy was collimated into a pencil beam (from 1 mm to 0.025 mm). FXCT clearly imaged endogenous iodine of thyroid and iodine labeled BMIPP in myocardium, whereas transmission x-ray CT could not demonstrate iodine. The distribution of iodine was heterogeneous within thyroid cancer, and its concentration was lower than that of normal thyroid. Distribution of BMIPP in normal rat myocardium was almost homogeneous; however, reduced uptake was slightly shown in ischemic region. FXCT is a highly sensitive imaging modality to detect very low concentration of specific element and will be applied to reveal endogenous iodine distribution in thyroid and to use tracer study with various kinds of labeled material.

A very simple and inexpensive CT-scanner has been designed and constructed, which is able to carry out contemporaneously transmission, Compton, Rayleigh and fluorescence radiation tomography. Four detectors are located around the object to be scanned: a NaI one at 180 degrees with respect to the incident radiation for transmission tomography; a second NaI at 90 degrees for Compton tomography; a third NaI at 5-10 degrees for Rayleigh tomography, and a Si-PIN or CdZnTe at 90 degrees for fluorescent radiation tomography. Special algorithms were employed, which include auto-absorption correction terms for Compton, Rayleigh and fluorescence tomography.

Transmission tomography is a powerful tool in several fields of investigation, ranging from medicine to industrial quality control. It is based on the radiation that doesn't interact with the sample and that reaches the detector. However, this kind of technique cannot always be used or the information from it is poor. In some of these cases other kinds of tomography can be applied such as scattering (Compton or Rayleigh) tomography or fluorescence tomography. The use of the latter techniques requires a different reconstruction technique of that used in transmission tomography. Some adaptation of the backprojection algorithm is often used, but in this case a complete scan of the sample is required with a fixed geometry. Another type of reconstruction algorithms are the iterative ones, but they present a high computational cost and so only small, low spatial resolution matrix, can be treated. In the past another kind of scanning techniques has been proposed. It is based on two linear translations (x-y) against translation and rotation required by the backprojection algorithm. The x-y scanning presents a big advantage compared with the backprojection scanning, i.e. the reconstruction does not need to be performed on the whole sample; it can also be performed on a part of the sample, the region of interest (ROI). However this scanning technique is affected by a big drawback: the influence of x-ray self-absorption by the matrix is stronger than the backprojection scanning producing a lower quality of the reconstruction. In this paper a recently developed correction technique is described.

A critical point of several reconstruction and analysis algorithms in x-ray experiments is a fast simulation of the interaction of radiation with matter. This kind of simulation is usually based on Monte Carlo techniques, which follows each particle individual trajectory. Since the maximum number of interactions is a user-definable integer, Monte Carlo simulations allow to obtain an arbitrary precision. However, in several experiments the flux of photons that reach the detector after the interaction in the volume of interest (VOI) is very low, therefore the simulation time may be very large. Simple experiments of x- ray tomography may require several days to obtain reasonable statistics with the faster Monte Carlo codes. Particularly, in x-y scanning tomography both the detector and the x-ray tube are highly collimated. In such cases, conventional Monte Carlo techniques are inadequate. As a possible alternative, we propose an analytical spectrum generator, which evaluates the detected signal through the differential cross section for the single interaction with corrections for absorption of the beam (before the interaction point) and of the scattered photon (after the interaction point). It will be shown that the analytical projector proposed in this paper is several order faster than Monte Carlo based simulators.

Conventional algorithms for tomographic reconstruction require a discrete set of projections equally spaced over the full angular range of 180 degrees for a parallel beam or 180 degrees plus fan angle for a fan beam. A crucial point is the availability of a complete set of data. However, in some cases this requirement cannot be fulfilled. This happens, for example, in case of large objects, such as a pipeline or a wall, or when part of the projections was lost. In order to perform a reconstruction of the image from the partial set of projections, the data must be pre- processed. Several algorithms have been reported in literature, but the majority of them require a-priori knowledge of the shape and composition of the sample or they present a high computational cost. Recently a new algorithm has been proposed. It allows to recover the lacking projections without any a-priori assumption and with a relatively low computational cost. It is based on a morphing technique, which affords in general terms the problem of curve matching and has been specialized to the case of tomographic reconstruction. It has been applied to medical (transmission) tomography. In the present work such algorithm is applied to microtomographic measurements of different types (transmission, Compton and fluorescence tomography), which have been performed on industrial samples.

This work describes the setup of an experimental system for microtomography developed in the framework of a collaboration between the Physics Department of the University of Bologna (Italy) and the Geosphaera Research Center of Moscow (Russia). The main goal of this inspection system is to carry out high-resolution analysis in vitro of biomedical samples as well as nondestructive testing (NDT) of industrial components. The detection system consists of a 30x15 mm² rectangular fiberoptic taper (ratio 2:1) optically coupled to a cooled 12-bit CCD camera (1024x512 pixels). On the entrance window of the taper is deposited a thin layer of Gd₂O₂S:Tb phosphor which provides the X-light conversion. The image readout is carried out by means of a commercial frame grabber installed on a personal computer and specific software is used for data acquisition and control of the tomographic process. The object under investigation is arranged on a 3-degree micro-positioning system (x-y translation and rotation) and irradiated by an X-ray microfocus beam (up to 200 kVp). The sample can be positioned easily along the source-detector axis in order to obtain a large magnification of details of interest. The X-ray detector has been intensively tested in order to determine its performance in terms of MTF, NPS, and DQE. Moreover, preliminary tests have been carried out on several samples in order to evaluate the performance of the micro-CT system.

Osteoporosis is the most common type of metabolic bone disease generating morphological alterations of the bone structure. Therefore, an intensive and accurate study of cancellous bone architecture is required to individuate the origin of the disease and to estimate its evolution. For this purpose, a specific project is in progress at the Physics Department of Bologna to carry out microtomography analysis in vitro of animal bone samples. The inspection system mainly consists of an X-ray microfocus source to irradiate the sample and of a CCD-based detector for the detection of the radiographic image. A sample with a diameter up to 30 mm and a height of 15 mm can be investigated over its whole volume. Three-dimensional images of the bone structure can be obtained with a spatial resolution variable from 30 up to few microns. A pig bone specimen has been investigated to test the equipment and to carry out intensive analysis and modeling of bone architecture. Moreover, a specific volume data processing procedure has been developed and tested to extract morphometric measurements of the bone structure.

Attenuation-contrast tomography with monochromatic thermal neutrons was developed and operated at guide station S18 of the institute Laue-Langevin in Grenoble. From the S18 spectrum the neutron wavelength (lambda) equals 0.18 nm was selected by employing a fore crystal with the silicon 220 reflection at a Bragg angle (Theta) equals 30 degrees. Projections were registered by a position sensitive detector (PSD) consisting of a neutron-to-visible-light converter coupled to a CCD detector. Neutron tomography and its comparison with X-ray tomography is studied. This is of special interest since the cross section for neutron attenuation ((sigma) _atom) and the cross section for neutron phase shift (b_c) are isotope specific and, in addition, by no means mostly monotonous functions of atomic number Z as are attenuation coefficient ((mu) _x) and atomic scattering amplitude (f) in the case of X-rays. Results obtained with n-attenuation tomography will be presented. Possibilities and the setup of an instrument for neutron phase-contrast tomography based on single-crystal neutron interferometry will be described.

This work focuses on the investigation of the distribution of contaminants in individual sediment particles from the New York/New Jersey Harbor. Knowledge of the spatial distribution of the contaminants within the particles is needed to enable (1) more sophisticated approaches to the understanding of the fate and transport of the contaminants in the environment and (2) more refined methods for cleaning the sediments. The size of the investigated particles ranges from 30-80 microns. Due to the low concentration of the elements of interest and the microscopic size of the environmental particles in these measurements, the small size and high intensity of the analyzing X-ray beam was critical. The high photon flux at the ESRF Microfocus beam line (ID13) was used as the basis for fluorescence tomography to investigate whether the inorganic compounds are taken upon the surface organic coating or whether they are distributed through the volume of the grains being analyzed. The experiments were done using a 13 keV monochromatic beam of approximately 2 micrometers in size having an intensity of 10¹⁰ ph/s, allowing absolute detection limits on the 0.04-1 fg level for Ti, Cr, Mn, Fe, Ni, and Zn.

The coherence of third generation synchrotron beams makes a trivial form of phase-contrast imaging possible. It is based on propagation and corresponds to the defocusing technique of electron microscopy. The propagation technique can be used either in a qualitative way, mainly useful for edge- detection, or in a quantitative way, involving numerical retrieval of the phase from images recorded at different distances (typically three or four) from the sample. The combination with tomography allows to reconstruct the electron density in the sample with micrometer resolution. This combined approach is called holotomography. It was applied to several problems in materials and life sciences when it is crucial to enhance the sensitivity or reduce the dose compared to absorption tomography. Pure phase objects such as foams and fleece structures can be imaged with excellent contrast and resolution. Holotomography turned out to be a invaluable tool to study semi-solid materials with two metallurgical phases that have similar attenuation coefficients. The attenuation and density map yield in this case complementary information, the latter being the useful one to study the connectivity of the solid phase. The dose reduction and increased sensitivity in phase imaging are crucial for imaging thick (millimeter range) biological samples in their natural, wet environment. Results obtained on Arabidopsis plant indicate the possibility to investigate at the micron scale the spatial organisation of plant cells.