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This article describes the implementation of microwave tomography for industrial process applications. Microwave tomography for industrial process imaging has different requirements from that for medical imaging. In addition to spatial resolution, high temporal resolution or real-time imaging is also important for high-speed processes, flows, or rapid reactions. Depending on the specific application, both quantitative imaging and qualitative imaging may be needed. Qualitative imaging would be sufficient to display distributions, patterns, or shapes, which may be adequate for some applications. Quantitative imaging would, however, be more informative, giving images with quantitative dielectric contrast or permittivity values from which other physical parameters, such as density, moisture content, and phase fraction, may be derived. With the microwave tomography approach described, several example applications in industrial processes are demonstrated, and a number of experimental imaging results are presented.

The paper discusses the capabilities of industrial computed tomography (CT) in the field of dimensional measurement of products with close tolerances. Computed tomography is a method that allows inspection and measurements of both reachable and unreachable characteristics which makes it very desirable and interesting for application in wide range of industries. In order to evaluate the quality of measurement results obtained by industrial CT, two objects with the same geometry, and made from different materials, were measured. Results obtained with CT were compared with the results obtained by coordinate measuring machine, which were considered to be reference values, and deviations between the results have been analysed. Measurements were repeated five times under repeatability conditions. Repeatability is expressed quantitatively in terms of the dispersion characteristics of the results. Statistical analysis showed that in majority of cases, there were no statistically significant differences between measurement results of equal characteristics obtained at different materials. Obtained deviations in the research could be explained by the fact that the measurements were performed at the industrial CT for general applications. Much better results can be achieved by using a metrology CT device.

The use of three-dimensional (3D) printing allows for creation of custom models for clinical care, education, and simulation. Medical imaging, given the significant role it plays in both clinical diagnostics and procedures, remains an important area for such education and simulation. Unfortunately, the materials appropriate for use in simulation involving radiographic or ultrasound imaging remains poorly understood. Therefore, our study was intended to explore the characteristics of readily available 3D printing materials when visualized by computed tomography (CT) and ultrasound.Seven 3D printing materials were examined in standard shapes (cube, cylinder, triangular prism) with a selection of printing methods ("open," "whole," and "solid" forms). For CT imaging, these objects were suspended in a gelatin matrix molded to match a standard human CT phantom. For ultrasound imaging, the objects were placed in acrylic forms filled with a gelatin matrix. All images were examined using OsiriX software.Computed tomography imaging revealed marked variation in materials' Hounsfield units as well as patterning and artifact. The Hounsfield unit variations revealed a number of materials suitable for simulation various human tissues. Ultrasound imaging showed echogenicity in all materials, with some variability in shadowing and posterior wall visualization.We were able to demonstrate the potential utility for 3D printing in the creation of CT and ultrasound simulation models. The similar appearance of materials via ultrasound supports their broad utility for select tissue types, whereas the more variable appearance via CT suggests greater potential for simulating differing tissues but requiring multiple printer technologies to do so.

The needs and the feasibility of simultaneous computed tomography (CT) and magnetic resonance imaging (MRI) were recently reported. In this paper, a spiral magnetic resonance X-ray CT (MRX) imaging system is proposed for head and extremities imaging, which serves as a simple, cost-effective solution on the path to a full-scale CT-MRI fusion. While MRI and X-ray radiography were integrated before, we propose novel designs to acquire simultaneous CT and MR views for synchronized radiographic imaging or joint tomographic reconstruction. Our preliminary permanent magnet configurations achieve a magnetic field strength between 0.1 and 0.2 T while keeping weight low enough for portability. We have also shown that a field strength up to 0.35 T is achievable with permanent magnets that maintain a compact profile, though increased weight would hinder ease of transportation. Simulation results of a joint tomographic reconstruction scheme show the advantage of simultaneously acquired images. The proposed MRX system performs double helical scans in CT and MRI mechanisms, and has multiple niche applications, such as medical imaging on disaster sites, in battle fields, and for under-developed regions.

This study describes the development of a multisource computed tomography (CT) system that proved to be a useful tool to study multiphase systems. In this CT system, two different radioisotope sources, 192 Ir (317 keV and 448 keV) and 137 Cs (662 keV), were placed in a single lead collimator and several tomography measurements carried out. The multisource CT system was capable of determining as well as differentiating the attenuation coefficients of materials with two phases (gas and liquid). It was also able to provide important information concerning the hydrodynamics occurring inside a multiphase column.

The main advantages of the use of computed x-ray tomography for nondestructive testing of the state of the internal structure of laminated polymer composite materials with the aim of improving the quality of manufacture of products from composites have been demonstrated.

This chapter focuses on the hardware of current and emerging X-ray computed tomography (CT) systems. First, the basic configuration of industrial cone-beam X-ray CT systems is recalled. Subsequently, individual hardware components, such as sources, detectors and kinematic systems, are described. The chapter continues with an overview of novel developments that expand the application domain of X-ray CT towards, for example, larger objects or fully integrated in-line systems. The chapter is concluded by a description of key safety elements for operation of X-ray CT systems.

We introduce an ultrasonic quantitative imaging method for long bones based on full-waveform inversion. The cost function is defined as the difference in the L 2-norm sense between observed data and synthetic results at a given iteration of the iterative inversion process. For simplicity, and in order to reduce the computational cost, we use a two-dimensional acoustic approximation. The inverse problem is solved iteratively based on a quasi-Newton technique called the Limited-memory Broyden-Fletcher-Goldfarb-Shanno method. We show how the technique can be made to work fine for benchmark models consisting of a single cylinder, and then five cylinders, the latter case including significant multiple diffraction effects. We then show pictures obtained for a tibia-fibula bone pair model. Convergence is fast, typically in 15 to 30 iterations in practice in each frequency band used. We discuss the so-called 'cycle skipping' effect that can occur in such full waveform inversion techniques and make them remain trapped in a local minimum of the cost function. We illustrate strategies that can be used in practice to avoid this. Future work should include viscoelastic materials rather than acoustic, and real data instead of synthetic data.

Process tomography (PT) techniques have been developed rapidly for visualizing the internal behavior of industrial processes, e.g. multi-phase flow measurement. Most of tomography systems employ a single measurement technique, such as computerized tomography (CT), optical tomography (OT), electrical resistance tomography (ERT) or electrical capacitance tomography (ECT). It is now possible to fit two or more tomographic systems to an industrial process. Detailed information from different modalities can be gained by inspection of separate tomographs, and the advantage of the strongest features provided by each unit can be taken. A combined tomogram can be produced of superior quality to any of the separate tomograms. To maximize the information available from the combined tomographic system, data fusion is the better option. In this paper, a dual-mode tomography system based on capacitance sensor and gamma sensor was developed to capture oil–gas two-phase flow. The two modalities can work at the same time. Two fusion methods, namely image fusion method and data fusion method, are proposed. Both simulation and static experiments for oil–gas two-phase flow were conducted. The reconstruction results of different fusion methods and modalities were compared and discussed.

X-ray luminescence and X-ray fluorescence computed tomography (CT) are two emerging technologies in X-ray imaging that provide functional and molecular imaging capability. Both emission-type tomographic imaging modalities use external X-rays to stimulate secondary emissions, either light or secondary X-rays, which are then acquired for tomographic reconstruction. These modalities surpass the limits of sensitivity in current X-ray imaging and have the potential of enabling X-ray imaging to extract molecular imaging information. These new modalities also promise to break through the spatial resolution limits of other in vivo molecular imaging modalities. This paper reviews the development of X-ray luminescence and X-ray fluorescence CT and their relative merits. The discussion includes current problems and future research directions and the role of these modalities in future molecular imaging applications.

The image of the current non-destructive testing system using a high energy accelerator is limited to conventional two-dimensional metaphysical information. Requirements for the present manufacturing industry are growing rapidly and include quantitative measurements, high-density component model extraction, reverse process development and precision inspection to meet the needs for the verification of manufactured goods. Therefore, industrial three-dimensional high-penetration tomography has emerged as the most promising method. In this study, in order to evaluate the applicability of a MeV-level high-energy accelerator, we developed a three-dimensional tomography system using a 450 kV X-ray generator. Evaluation of the three-dimensional tomography image is based on measurements of the penetration and the image resolution for high-energy X-rays.

Gamma-ray computed tomography (CT) is a powerful non-invasive imaging technique for viewing an object in 2-D or 3-D cross-section images without the need to physically section it. The invention of CT technique revolutionised the field of medical diagnostic imaging because it provides more detailed and useful information than any previous non-invasive imaging technique. The method is increasingly used in industrial fields. This paper describes the development of a gamma-ray computed tomography system for imaging and visualising of industrial multiphase reactors. The theoretical aspects of CT scanner, the system configurations and the adopted algorithm for image reconstruction are discussed. Penetrating radiation from an isotopic gamma-ray source of Cs-137 and a bank of NaI(Tl) scintillation detectors in combination with a dedicated mechanical gantry set-up were used to construct the CT system. During scanning, the movement of the detector’s bank and rotation table is controlled by a LabView-based software. The software is also designed to control all associated nuclear electronics equipments and finally to acquire gamma-ray transmission data. The image reconstruction is performed by using Expectation-Maximisation (EM) and Alternating-Maximisation (AM) algorithms written in Visual-Fortran programming language. Several physical phantoms to simulate industrial multiphase process columns and reactors were scanned using this CT scanner. Some of the reconstructed images are presented in this paper.

As a rather new technology, X-Ray Computed Tomography offers new and promising possibilities in manufacturing metrology in comparison to well-established tactile or optical measurements. The main benefit is the volumetric model which results of each measurement and represents the measurement object holistically with high point density.

Neutron computed tomography is an important imaging tool in the field of non-destructive testing and in fundamental research for many engineering applications. Contrary to X-rays, neutrons can be attenuated by some light materials, such as hydrogen, but can penetrate many heavy materials. Thus, neutron computed tomography is useful in obtaining important three-dimensional information about a sample's interior structure and material properties that other traditional methods cannot provide. The neutron computed tomography system at the Pennsylvania State University's Radiation Science and Engineering Center is being utilized to develop a water quantification technique for investigation of water distribution in fuel cells under normal conditions. A hollow aluminum cylinder test sample filled with a known volume of water was constructed for purposes of testing the quantification technique. Transmission images of the test sample at different angles were easily acquired through the synthesis of a dedicated image acquisition computer driving a rotary table controller and an in-house developed synchronization software package. After data acquisition, Octopus (version 8.2) and VGStudio Max (version 1.2) were used to perform cross-sectional and three-dimensional reconstructions of the sample, respectively. The initial reconstructions and water quantification results are presented.

A new neutron tomography imaging system was developed in order to realize high-quality three-dimensional (3D) and four-dimensional (4D) visualizations by fusing the high-frame-rate neutron radiography and computed tomography (CT) techniques. The fundamental idea is that the object is revolved with high rotating speed and the neutron radiography images are recorded with a high-speed video camera and an image intensifier, and then the consecutive images are processed by a 3D CT technique. The 4D dynamic images of the sand flow in the sandglasses could be visualized clearly. This new technique has also an advantage in that it can reduce radio-activation of the object materials remarkably.

The present work describes the development of a new detection technology for medical imaging using the method of Single-Photon Emitted Computed Tomography (SPECT) combined with X-rays Computed Tomography (CT). Our ultimate goal is to advance disease detection by imaging quantitatively molecular agents and localizing their distribution in tissues and organs by SPECT simultaneously with the anatomical CT image. To assess the imaging characteristics of the imaging agents developed, we tested and advanced a detection technique first developed for high-energy physics: Gas Electron Multipliers (GEMs).

The amelioration of present X-ray imaging systems especially in computed tomography to resolutions below 1 μm necessitates very precise equipment details such as the manipulators, focus size and stability of the tube and the detector adjustment. In this paper, we present an experimental setup of a computed tomography system with sub-micrometer resolution. The requirements on and characteristics of the components and their influence on the measurements are discussed and exemplary results of different test objects in the field of non-destructive testing with sub-micrometer resolution are presented.

Process tomography (PT) techniques have been developed rapidly for visualising the internal behaviour of industrial processes. Most tomography systems employ a single measurement technique, such as Electrical Resistance Tomography (ERT) or Electrical Capacitance Tomography (ECT). Although single-modality process tomography systems provide sufficient information for some applications, in other applications, e.g. three-phase flow, additional information is required. In fact, many industrial processes are complex and contain multiple components, which require multiple measurement techniques to individually quantify them. To facilitate this process, a multi-modal process tomography system must allow individual modality data to be collected and combined effectively. This paper describes opportunities for rationalisation and sharing of resources that have been exploited to create a dual-modality tomography system.

X-ray computed tomography (XCT) with flat-panel matrix detectors is a promising non-destructive method to scan and characterize external and internal structures of a specimen. Using XCT, both size and topology of different types of heterogeneities may vary largely. The different size scales of the heterogeneities and of the affected material volume require appropriate tomographic methods, scanning geometries and resolutions. In order to quantify features of interest from XCT scans, a major challenge is still found in the analysis and visualization of the generated XCT data: Advanced 3D-image processing techniques are needed for robust extraction and characterization of each single feature of interest. Interactive visualization techniques are needed for further exploration and analysis of these increasingly complex data spaces in order to provide novel insights for domain specialists. As examples of how image processing and visualization complement XCT various application cases are presented.

Head computed tomography (CT) plays an important role in the comprehensive evaluation of acute stroke. Photon-counting spectral detectors, as promising candidates for use in the next generation of x-ray CT systems, allow for assigning more weight to low-energy x-rays that generally contain more contrast information. Most importantly, the spectral information can be utilized to decompose the original set of energy-selective images into several basis function images that are inherently free of beam-hardening artifacts, a potential advantage for further improving the diagnosis accuracy. We are developing a photon-counting spectral detector for CT applications. The purpose of this work is to determine the optimal beam quality for material decomposition in two head imaging cases: nonenhanced imaging and K-edge imaging. A cylindrical brain tissue of 16-cm diameter, coated by a 6-mm-thick bone layer and 2-mm-thick skin layer, was used as a head phantom. The imaging target was a 5-mm-thick blood vessel centered in the head phantom. In K-edge imaging, two contrast agents, iodine and gadolinium, with the same concentration ([Formula: see text]) were studied. Three parameters that affect beam quality were evaluated: kVp settings (50 to 130 kVp), filter materials ([Formula: see text] to 83), and filter thicknesses [0 to 2 half-value layer (HVL)]. The image qualities resulting from the varying x-ray beams were compared in terms of two figures of merit (FOMs): squared signal-difference-to-noise ratio normalized by brain dose ([Formula: see text]) and that normalized by skin dose ([Formula: see text]). For nonenhanced imaging, the results show that the use of the 120-kVp spectrum filtered by 2 HVL copper ([Formula: see text]) provides the best performance in both FOMs. When iodine is used in K-edge imaging, the optimal filter is 2 HVL iodine ([Formula: see text]) and the optimal kVps are 60 kVp in terms of [Formula: see text] and 75 kVp in terms of [Formula: see text]. A tradeoff of 65 kVp was proposed to lower the potential risk of skin injuries if a relatively long exposure time is necessarily performed in the iodinated imaging. In the case of gadolinium imaging, both SD and BD can be minimized at 120 kVp filtered with 2 HVL thulium ([Formula: see text]). The results also indicate that with the same concentration and their respective optimal spectrum, the values of [Formula: see text] and [Formula: see text] in gadolinium imaging are, respectively, around 3 and 10 times larger than those in iodine imaging. However, since gadolinium is used in much lower concentrations than iodine in the clinic, iodine may be a preferable candidate for K-edge imaging.

Computed tomography (CT) with X-rays is widely used in medicine and nondestructive testing today. However, in process applications X-ray tomography has so far been more seldom used, obviously due to its high complexity and costs. Nonetheless, particularly in laboratory studies it has frequently proven its superior capability to measure multiphase flow parameters, such as local phase fractions in pipes, vessels, or other process system components, with high resolution and accuracy. Most recently, different technologies were presented that allow faster tomographic imaging of flows with X-ray CT, which now opens the door for a wider application of this technique in process analysis, monitoring, and control. The chapter gives a concise overview of basic principles and hardware of X-ray CT, particularly with respect to process applications, and provides state-of-the-art examples of its application in multiphase flow analysis.

This paper deals with tomographic techniques for two-dimensional spatially resolved concentration measurements indoors. This represents a significant advance over the traditional point measuring me ...

Computed tomography has revolutionized diagnostic radiology with the introduction of spiral CT in the early 1990s, allowing for the first time the acquisition of volume data without the danger of misregistration or double registration of anatomical details. The next revolution occurred in 1998 when all major CT manufacturers introduced multislice CT (MSCT) systems, which typically offered simultaneous acquisition of four slices, providing considerable improvement towards the goal of isotropic three-dimensional imaging. The most recent generation of MSCT systems acquire 64 slices per rotation, enabling a whole body CTA with 1,500 mm scan range and an isotropic resolution of down to 0.4 mm in only 22- 25 s. The tube and the detector measurement system belong to the most important system components of a CT system, having a large influence on system performance. For example, new rotating envelope tube design principles allow for faster rotation times and for double z-sampling techniques in order to increase resolution. The applied dose is ultimately the limiting factor for the improvement of image quality and increase in isotropic resolution. In order to make best diagnostic use of the applied dose, sophisticated dynamic dose adaptation techniques to patient size and geometry have been developed.

Summary Computed tomography utilises a rotating X-ray source combined with multiple detectors in the latest scanners. This data can then be processed in numerous ways to provide axial, multi-planar and 3D images for diagnostic purposes. This modality has rapidly developed since its inception in direct relationship to the exponential increase in computer technology with a corresponding increase in its range of applications.

Industrial Computed Tomographic (ICT) imaging systems based on X-rays require a high stability source. This emanates from the fact that in a computed tomographic imaging system, statistical variation inherent in the penetrating radiation used to probe the specimen, electronic noise generated in the detection system and reconstruction errors play an important role in the overall quality of the image. A conventional industrial X-ray machine used for routine radiography work is not suitable for tomographic imaging applications because of its output dose variations. In this paper, an experiment is described to utilise a general-purpose 160 kV constant potential industrial X-ray machine with significant ripple in its output beam, in an experimental Computed Industrial Tomographic Imaging System (CITIS) developed at Isotope Applications Division of Bhabha Atomic Research Centre. Studies carried out include the analysis of temporal profile of X-ray beam intensity and online averaging of detected signals for the minimization of periodic ripple, which mainly showed up, at the power line frequency. A tomographic image of a typical specimen, reconstructed with the processed projection data is analysed. It was observed that the mean value of reconstructed linear absorption coefficients and standard deviation computed over a window within a constant density region of the object were stable

The objective of this study is to develop and test a unique X-ray-induced acoustic computed tomography system that combines the advantages of high X-ray imaging contrast and high ultrasonic spatial resolution. The system features a 5 MHz 128-element ultrasound transducer ring-array formed into a full circular aperture. A parallel data receiver, which consists of a dedicated 128-channel preamplifier and a 128-channel data acquisition module, provides full tomographic imaging at a speed of up to 25 frames per second. Details of the system design and calibration are presented, along with the characteristic results of the imaging resolution. The tomographic imaging performance is demonstrated through images of a phantom with a spatial resolution up to 138 μm. The study results indicate that this imaging device and the methodology provide a rapid and high resolution approach for the dynamic imaging of information, and it may have the potential for becoming a promising noninvasive imaging modality to be used in...

The inspection system is crucial to ensure the system is always in a good condition. A technique that can be used for inspection system is process tomography. By promising non-destructive approach; various types of process tomography applied in civil, manufacturing and electrical applications. The purpose of this paper is to review the types of process tomography such as ultrasonic tomography, x-ray tomography, optical tomography, electrical resistance tomography, and electrical impedance tomography that had been applied to the inspection system. Variety techniques of inspection based on those sensors briefly discussed in this paper. The result showed that the process tomography expanded tremendously in the inspection system. Finally, a potential future research on the inspection system in the civil application proposed in this paper.

This paper presents a reconstruction method for a conveyor belt X-ray scanning geometry, consisting of a static X-ray source/detector system and an object in uniform motion. Applying conventional reconstruction methods to data acquired in this geometry leads to severe artefacts. We show that by incorporating prior knowledge of the material as well as domain specific knowledge, such artefacts can be largely reduced. This is done by combining concepts of discrete tomography with the expected object domain.

Tomography is a method that has been used for image reconstruction in the medical and engineering fields. Optical tomography is one of the various methods applied in tomography systems. This tomography method is widely used in the medical and processing industries fields because of its special characteristics, such as immunity to electrical noise and interference, high resolution and its hard field sensors. The basic principle of the optical tomography system in measuring an object is based on its wave and radiation source. This article is a review of the characteristics of light and its interaction with matter, the types of optical tomography system, the basic construction of an optical tomography system, types of optoelectronic sensors and image reconstruction.

In this chapter, we briefly recall the theory of non-commutative tomography in a pedagogical way. We then consider its applications to signal analysis. The advantages and drawbacks of these techniques to finite samples of data are discussed. Then the method is applied, first to signals originating from reflectometry measurements in magnetized fusion plasmas, and then to data obtained from the advection of tracers in a two-dimensional time-dependent flow generated by three point vortices. In the first case, we show that the tomogram allows to pick a base to represent our signal which has the advantage of isolating the reflection coming from the plasma and then to improve the estimation of the density profile. In the second case, we show how, with a "tricky transformation" the method allows us to detect Lévy flights and extract some of their properties.

In contrast to X-rays, neutrons can penetrate most metals easily. Neutron attenuation is strongly isotope dependent, and a high contrast is possible for many light-weight elements. Especially their high sensitivity for hydrogen makes them a valuable tool for the detection of organic materials like lubricants, plastics or sealants within metal housings. Neutron radiography and tomography complement the application of X-rays for the inspection of complex and critical components like in automotive and aerospace applications. However, the requirements for beam geometry are much higher for tomography than for simple radiography because the sample cannot be close to the detector, as the sample has to be rotated in the beam, usually by 180°. This paper gives an overview on tomography requirements and limitations, applications and future prospects.

SummaryMinimally invasive procedures are increasingly combined with radiologic imaging to optimise access and treatment techniques. While endoscopy has become a standard technique in the surgical field for diagnosis and therapy, tomographic guidance is new. Combining both modalities, the transparency of computed tomography and of ultrafast electron beam tomography, together with magnetic resonance imaging (MRI), will optimise both guidance and therapy. By using tomographic scanners for precise instrument positioning, the diameter of instruments [mechanical, laser, radiofrequency (RF), endoscopes etc.] can be minimised. Also electronic equipment, for visualisation and therapy should be integrated into a tomographic work-station. Instruments and electronic equipment are sensitive to MRI and ferromagnetic alloys, and electric impulses cause artifacts in imaging. These problems have to be solved for future therapeutic workstations.

X-ray computed tomography (CT) provides quantitative, readily interpretable data and enables the inspection of structures that are not amenable to any other nondestructive evaluation technique. As a result, CT has become well established as an inspection, evaluation, and analysis tool in industry. Many of the applications have been in the aerospace industry, where the high cost and performance requirements of components justifies the cost of CT inspection, but use in other industries is growing as equipment becomes increasingly available.

This work describes a multi-source computed tomography. It showed to be a feasible tool to study multiphase systems. In this CT scanner, two different radioactive sources, 192Ir and 137Cs, were placed together into a single lead collimated system. The CT is capable to determine and differentiate the attenuation coefficients of materials constituted of three phases (gas, liquid and solid), using two or more different radioisotope energies.

The performance of the MARS-CT has been evaluated and found to be acceptable for our soft-tissue imaging research applications. The spectroscopic response of CT number is characteristic of the relevant test materials. Corrections for beam hardening and ring artefacts are required for accurate results. Further optimization of system parameters will be required for specific applications.

In this paper a review of the development of x-ray computed tomography (CT) for non-destructive failure analysis in microelectronics packages and boards is presented. The general operation principle, key design considerations and technical challenges faced by x-ray CT technology are discussed. A comparison between 2D and 3D x-ray imaging capabilities is presented, and critical failure analysis case studies for first and second level interconnect that are hard or not possible to isolate by alternative methods are also discussed, as well as its unique progressive testing capability.

Hydraulic fracturing is a widely used technique for production enhancement. One critical property of a hydraulic fracture is the fracture conductivity, which has a direct impact on the productivity and hence, the economics of the stimulated well. Several laboratory techniques have been developed to characterize the materials that are placed in the fracture and influence its conductivity. Conductivity laboratory measurements have become a routine experiment with well-established procedures and setups aimed at simulating downhole conditions. However, correlating the performance of materials in a conventional laboratory setup with their performance in real conditions is not straightforward. This problem occurs because conventional laboratory setups are of limited length scale and fail to capture processes and variations that occur at a scale of the order of, or exceeding, the dimensions of the conductivity cell. Also, even if conventional setups provide accurate and reproducible measurements, they fail to provide fundamental, in-depth understanding of the actual processes that occur at the pore scale, occur in the fracture, and influence the fracture conductivity. A unique, large-scale X-ray computer tomography (CT) setup improves understanding of the factors influencing fracture conductivity. The state-of-the-art setup allows taking high-resolution scans of a proppant pack under conditions similar to an actual fracture. The setup provides unique insight into static and dynamic phenomena occurring at the proppant and the pore scale. The use of imaging software then provides an accurate 3D image over the entire length of the proppant pack. Computer models of flow in porous media can then be used to predict the flow and its parameters in the propped fracture and its porous network specified by the high-resolution images. Moreover, the setup scale (1 m long) is much larger than that of a conventional conductivity cell (20 cm long). The larger dimensions are adequate to capture heterogeneous processes such as fracture cleanup. The performance of the new setup was validated using baseline proppant pack conductivity and non-Darcy flow coefficients experiments. An example was also shown where the unique X-ray CT setup was used for investigating fracture cleanup of new, elongated rod-shaped nondeformable high-strength proppant compared with conventional spherical proppant. The CT images show how the new proppant provides a better fracture cleanup compared with spherical proppant. For both cases, images showing the distribution of residual gel saturation highlight how pore volume geometry affects fracture cleanup.

We first clarify the measurement process of fluorescent x-ray computed tomography using synchrotron sheet-beam. Then, we propose the analytical reconstruction method, and show its efficacy by computer simulation.

We have investigated the effect of a sample structure on reconstruction quality in computed tomography (CT). A power spectrum with respect to a projection angle is used to represent the sample structure. The condition for high quality reconstruction is then analyzed with the simulation and the electron tomography experiment based on an ultrahigh voltage electron microscope. The truncated terms in the power spectrum are suggested to be less than 10(-3) for high quality reconstruction. The effect of the sample structure is believed to be an important factor for high quality reconstruction of complex samples in various CT techniques.

In the majority of cases the term “tomography” is associated with computed X‐ray tomography. However several other physical interactions also have the ability to provide information from the inside of objects. Already traditional scanning acoustic microscopy (SAM) gives volume information for opaque materials. However, for most defect types in a homogeneous material the SAM C‐ and B‐Scans alone do not give a correct volume image. Algorithms processing data from different scan positions improve the situation significantly. But only when a number of additional measures are taken satisfactory results can be obtained. After describing the basic principles of SAM tomography an example of application is given and the results are compared to X‐ray tomography (CT) of the same object.

This chapter contains sections titled: General Principles of Imaging with X-Rays X-Ray Production Interactions of X-Rays with Tissue Linear and Mass Attenuation Coefficients of X-Rays in Tissue Instrumentation for Planar X-Ray Imaging X-Ray Image Characteristics X-Ray Contrast Agents X-Ray Imaging Methods Clinical Applications of X-Ray Imaging Computed Tomography Image Processing for Computed Tomography Spiral/Helical Computed Tomography Multislice Spiral Computed Tomography Radiation Dose Clinical Applications of Computed Tomography This chapter contains sections titled: Exercises Further Reading ]]>

Partial volume effects (PVE) in nuclear imaging blur contours and decrease intensity in small tissues. Among the methodologies considered for PVE correction, a new voxel-wise mutual multi-resolution approach (MMA) was recently introduced. MMA is based on the extraction and transformation of high resolution details from an anatomical image (MR or CT) and their subsequent incorporation into a low-resolution image (PET or SPECT). This voxel-wise approach allows lacking details of the low-resolution image to be reconstructed as well as contours and intensities to be recovered. However, artifacts may be introduced due to the required global linear correlation between both modalities and the current 2D implementation whereas PVE is a 3D phenomenon. The aim of the present study was to assess a new model, designed to overcome these two issues. A 3D wavelet decomposition process was built to replace the 2D global linear model with a 3D local analysis using a moving window. The algorithm was validated on synthetic and simulated images, and its performance was compared to the previous approach. The obtained quantitative correction was found to be similar to the 2D global correction in correlated cases whereas in the uncorrelated cases such as whole body or brain analysis, the new model outperforms the 2D approach without artefacts and with improved visual and quantitative correction.

SPECT (Single Photon Emission Computed Tomography) provides for an invaluable non‐invasive technique for the characterization and activity distribution of the gamma‐emitting source. For many applications of radioisotopes for medical and industrial application, not only the positional information of the distribution of radioisotopes is needed but also its strength. The well‐established X‐ray radiography or transmission tomography techniques do not yield sufficient quantitative information about these objects. Emission tomography is one of the important methods for such characterization. Application of parallel beam, fan beam and 3D cone beam emission tomography methods have been discussed in this paper. Simulation studies to test these algorithms have been carried out to validate the technique.

Tomography provides three-dimensional images of heterogeneous materials or engineering components, and offers an unprecedented insight into their internal structure. By using X-rays generated by synchrotrons, neutrons from nuclear reactors, or electrons provided by transmission electron microscopes, hitherto invisible structures can be revealed which are not accessible to conventional tomography based on X-ray tubes. This book provides detailed descriptions of the recent developments in this field, especially the extension of tomography to materials research and engineering. The book is grouped into four parts: a general introduction into the principles of tomography, image analysis and the interactions between radiation and matter, and one part each for synchrotron X-ray tomography, neutron tomography, and electron tomography. Within these parts, individual chapters written by different authors describe important versions of tomography, and also provide examples of applications to demonstrate the capacity of the methods.