Diffraction-enhanced X-ray Imaging Research Articles

Superheating Clathrate Hydrates for Anomalous Preservation

Tetrahydrofuran (THF)-hydrate crystal conglomerates were kept intact above their melting point by immersing them in cyclopentane (CP), as observed visually, and by diffraction-enhanced X-ray imaging. THF and CP form isostructural sII hydrates with melting points of 277.5 and 280.8 K, respectively. Placing the THF-hydrate crystal in CP converted the outer layer of THF-hydrate to a thin layer of CP-hydrate, which then prevented the THF-hydrate from melting at its usual melting point. The coated THF-hydrate melted at a temperature about 2 K higher than the usual melting temperature for THF-hydrate. Therefore, we can postulate that superheating less stable clathrate hydrates by coating them with hydrates of greater stability may be an approach suitable for the anomalous preservation of less stable clathrate hydrates, for example, fuel gases, for a considerable length of time for transport or storage.

X-ray phase-contrast methods

This review is devoted to a comparative description of the methods for forming X-ray phase-contrast images of weakly absorbing (phase) objects. These include the crystal interferometer method, the Talbot interferometer method, diffraction-enhanced X-ray imaging, and the in-line method. The potential of their practical application in various fields of science and technology is discussed. The publications on the development and optimization of X-ray phase-contrast methods and the experimental study of phase objects are analyzed.

Diffraction-enhanced X-ray imaging under low-temperature conditions: non-destructive observations of clathrate gas hydrates

Diffraction-enhanced imaging (DEI) is a phase-contrast X-ray imaging technique suitable for visualizing light-element materials. The method also enables observations of sample-containing regions with large density gradients. In this study a cryogenic imaging technique was developed for DEI-enabled measurements at low temperature from 193 K up to room temperature with a deviation of 1 K. Structure-II air hydrate and structure-I carbon dioxide (CO(2)) hydrate were examined to assess the performance of this cryogenic DEI technique. It was shown that this DEI technique could image gas hydrate coexisting with ice and gas bubbles with a density resolution of about 0.01 g cm(-3) and a wide dynamic density range of about 1.60 g cm(-3). In addition, this method may be a way to make temperature-dependent measurements of physical properties such as density.

Determination of hydrogen diffusivity depending on the hydride concentration in titanium-hydride by means of the diffraction-enhanced X-ray imaging method

Determination of hydrogen diffusivity depending on the hydride concentration in titanium-hydride by means of the diffraction-enhanced X-ray imaging method

In-Laboratory Diffraction-Enhanced X-Ray Imaging of an Equine Hoof

We describe and demonstrate the first application of a laboratory-based diffraction-enhanced X-ray imaging instrument for noninvasive equine imaging. A formalin-preserved disarticulated forelimb from a near-term aborted miniature horse fetus was imaged with diffraction-enhanced X-ray imaging. The resultant calculated images—absorption, extinction, refraction, and scattering—are presented, and soft-tissues such as the dorsal digital extensor tendon, articular cartilage, as well as various joint, tendon sheath, and bursa recesses are observed in simultaneous registration with the adjacent dense bone tissue. Radiation dose calculations were performed and a calculated surface dose of 0.6 mGy for the soft muscular tissue was determined for the imaging experiment.

Diffraction Enhanced X-ray Imaging of the Distal Radius: A Novel Approach for Visualization of Trabecular Bone Architecture

In Canada, osteoporotic fractures result in direct health care costs that exceed CAD$1.3 billion annually [1]. Fractures are related to compromised bone strength, a parameter that reflects both density (quantity) and architecture (quality) [2]. The current clinical standard for bone assessment, dual energy x-ray absorptiometry, provides only a 2-dimensional areal measurement of density and no architectural information [3]; therefore, the development of improved methods for visualizing and quantifying of bone architecture remains an important goal with respect to improving detection and treatment of osteoporosis. Advances are currently being sought in the development of new technologies [3], such as high-resolution peripheral quantitative tomography [4], and through texture-based analysis of trabecular structure from radiographs [5]. In this pictorial essay, we explore the use of x-rayebased diffraction enhanced imaging (DEI) by using synchrotron radiation [6] as a novel means of visualizing the internal architecture of the human distal radius, a clinically significant fracture site. Imaging for this study was conducted at the Canadian Light Source (CLS) synchrotron during commissioning of the BioMedical Imaging and Therapy (BMIT) bending magnet beam line [7]. As such, our goal here is 2-fold: (1) establishment of proof-of-principle

Vulnerability of the superficial zone of immature articular cartilage to compressive injury

The zonal composition and functioning of adult articular cartilage causes depth-dependent responses to compressive injury. In immature cartilage, shear and compressive moduli as well as collagen and sulfated glycosaminoglycan (sGAG) content also vary with depth. However, there is little understanding of the depth-dependent damage caused by injury. Since injury to immature knee joints most often causes articular cartilage lesions, this study was undertaken to characterize the zonal dependence of biomechanical, biochemical, and matrix-associated changes caused by compressive injury. Disks from the superficial and deeper zones of bovine calves were biomechanically characterized. Injury to the disks was achieved by applying a final strain of 50% compression at 100%/second, followed by biomechanical recharacterization. Tissue compaction upon injury as well as sGAG density, sGAG loss, and biosynthesis were measured. Collagen fiber orientation and matrix damage were assessed using histology, diffraction-enhanced x-ray imaging, and texture analysis. Injured superficial zone disks showed surface disruption, tissue compaction by 20.3 ± 4.3% (mean ± SEM), and immediate biomechanical impairment that was revealed by a mean ± SEM decrease in dynamic stiffness to 7.1 ± 3.3% of the value before injury and equilibrium moduli that were below the level of detection. Tissue areas that appeared intact on histology showed clear textural alterations. Injured deeper zone disks showed collagen crimping but remained undamaged and biomechanically intact. Superficial zone disks did not lose sGAG immediately after injury, but lost 17.8 ± 1.4% of sGAG after 48 hours; deeper zone disks lost only 2.8 ± 0.3% of sGAG content. Biomechanical impairment was associated primarily with structural damage. The soft superficial zone of immature cartilage is vulnerable to compressive injury, causing superficial matrix disruption, extensive compaction, and textural alteration, which results in immediate loss of biomechanical function. In conjunction with delayed superficial sGAG loss, these changes may predispose the articular surface to further softening and tissue damage, thus increasing the risk of development of secondary osteoarthritis.

In Situ Observation of Morphology Change on Alloy Anode by Diffraction Enhanced X-ray Imaging

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In‐laboratory diffraction‐enhanced X‐ray imaging for articular cartilage

The loss of articular cartilage characteristic of osteoarthritis can only be diagnosed by joint space narrowing when conventional radiography is used. This is due to the lack of X-ray contrast of soft tissues. Whereas conventional radiography harnesses the X-ray attenuation properties of tissues, Diffraction Enhanced Imaging (DEI), a novel radiographic technique, allows the visualization of soft tissues simultaneous with calcified tissues by virtue of its ability to not only harness X-ray attenuation but also the X-ray refraction from tissue boundaries. Previously, DEI was dependent upon synchrotron X-rays, but more recently, the development of nonsynchrotron DEI units has been explored. These developments serve to elaborate the full potential of radiography. Here, we tested the potential of an in-laboratory DEI system, called Diffraction-Enhanced X-ray Imaging (DEXI), to render images of articular cartilage displaying varying degrees of degradation, ex vivo. DEXI allowed visualization of even early stages of cartilage degeneration such as surface fibrillation. This may be of eventual clinical significance for the diagnosis of early stages of degeneration, or at the very least, to visualize soft tissue degeneration simultaneous with bone changes.

The design and application of an in-laboratory diffraction-enhanced x-ray imaging instrument

We describe the design and application of a new in-laboratory diffraction-enhanced x-ray imaging (DEXI) instrument that uses a nonsynchrotron, conventional x-ray source to image the internal structure of an object. In the work presented here, a human cadaveric thumb is used as a test-sample to demonstrate the imaging capability of our instrument. A 22 keV monochromatic x-ray beam is prepared using a mismatched, two-crystal monochromator; a silicon analyzer crystal is placed in a parallel crystal geometry with the monochromator allowing both diffraction-enhanced imaging and multiple-imaging radiography to be performed. The DEXI instrument was found to have an experimentally determined spatial resolution of 160+/-7 mum in the horizontal direction and 153+/-7 mum in the vertical direction. As applied to biomedical imaging, the DEXI instrument can detect soft tissues, such as tendons and other connective tissues, that are normally difficult or impossible to image via conventional x-ray techniques.

Analyzer-based x-ray phase-contrast microscopy combining channel-cut and asymmetrically cut crystals

An analyzer-based x-ray phase-contrast microscopy (ABM) setup combining a standard analyzer-based x-ray phase-contrast imaging (ABI) setup [nondispersive 4-crystal setup (Bonse-Hart setup)] and diffraction by asymmetrically cut crystals is presented here. An attenuation-contrast microscopy setup with conventional x-ray source and asymmetrically cut crystals is first analyzed. Edge-enhanced effects attributed to phase jumps or refraction/total external reflection on the fiber borders were detected. However, the long exposure times and the possibility to achieve high contrast microscopies by using extremely low attenuation-contrast samples motivated us to assemble the ABM setup using a synchrotron source. This setup was found to be useful for low contrast attenuation samples due to the low exposure time, high contrast, and spatial resolution found. Moreover, thanks to the combination with the nondispersive ABI setup, the diffraction-enhanced x-ray imaging algorithm could be applied.

Hydrogen diffusion in titanium‐hydride observed by the diffraction‐enhanced X‐ray imaging method

AbstractThe X‐ray refraction imaging technique was applied to the quantitative study of hydrogen diffusion in titanium‐hydride. Diffusivity and activation energy of hydrogen diffusion were determined by direct observation of the hydride. The hydride was formed on the surface of titanium by electrolytic‐charging at 31, 63 and 98 °C. The specimens were cut into 1 mm thick slices for cross‐sectional observations. The hydride layer was observed using the diffraction‐enhanced X‐ray imaging (DEI) method. Boundaries between titanium and the hydride were observed as thick black or white lines parallel to the specimen surface in the DEI images similar to previously reported results. Hydride distribution caused by hydrogen diffusion from the surface was calculated using an assumed hydrogen diffusivity value and from the solution of the appropriate diffusion equation. The results were converted to the intensity profiles of refraction images of the hydride using the measured rocking curve from an analyzer. The calculated intensity profiles were compared to those obtained from the experimental results and the fitted diffusivity was determined by trial and error. The activation energy of hydrogen in titanium‐hydride thus obtained, 0.55 ± 0.07 eV, showed good agreement with the widely accepted value obtained by the internal friction. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

High-resolution CT by diffraction-enhanced x-ray imaging: mapping of breast tissue samples and comparison with their histo-pathology

The aim of this study was to introduce high-resolution computed tomography (CT) of breast tumours using the diffraction-enhanced x-ray imaging (DEI) technique and to compare results with radiological and histo-pathological examinations. X-ray CT images of tumour-bearing breast tissue samples were acquired by monochromatic synchrotron radiation (SR). Due to the narrow beam and a large sample-to-detector distance scattering is rejected in the absorption contrast images (SR-CT). Large contrast enhancement is achieved by the use of the DEI-CT method, where the effects of refraction and scatter rejection are analysed by crystal optics. Clinical mammograms and CT images were recorded as reference material for a radiological examination. Three malignant and benign samples were studied in detail. Their radiographs were compared with optical images of stained histological sections. The DEI-CT images map accurately the morphology of the samples, including collagen strands and micro-calcifications of dimensions less than 0.1 mm. Histo-pathological examination and reading of the radiographs were done independently, and the conclusions were in general agreement. High-resolution DEI-CT images show strong contrast and permit visualization of details invisible in clinical radiographs. The radiation dose may be reduced by an order of magnitude without compromising image quality, which would make possible clinical in vivo DEI-CT with future compact SR sources.

New determination method of hydrogen diffusivity in titanium-hydrides by means of diffraction-enhanced X-ray imaging method

The X-ray refraction imaging technique, diffraction-enhanced X-ray imaging (DEI) method was applied to determine the hydrogen diffusivity in titanium-hydride. Hydride was formed on titanium surface by electrolytic-charging at room temperature for 6, 12, 18, 24 and 48 h. The specimen was cut into a 1-mm thick slice for cross-sectional observation. Hydride layer was observed by DEI method as a thick black or white line parallel to the surface. Hydride distribution caused by hydrogen diffusion from the surface was calculated using assumed hydrogen diffusivity and a solution of diffusion equation. And the results were converted to the intensity profile of refraction images of the hydride using the measured rocking curve from an analyzer. The intensity profile was compared with that obtained from the photographs and fitted diffusivity was decided by trial and error. The obtained diffusion coefficient of hydrogen in titanium-hydride, 3.6 x 10^-15 m-2/s, was slightly larger than the value obtained by internal friction at room temperature.

X-ray optics for emission line X-ray source diffraction enhanced systems

Diffraction-enhanced X-ray imaging (DEI) is one of a class of imaging techniques developed at a synchrotron that is based on contrast mechanisms other than absorption. This method uses perfect crystal optics to prepare and analyze beams that traverse the object imaged. The combination of a highly collimated beam along with an analyzer gives such system sensitivity to X-ray refraction and ultra-small-angle scattering contrast (extinction). The translation of the system used at the synchrotron to a conventional X-ray tube source has challenges that must be overcome for a practical system to be built. One of those restrictions is the propagation of unwanted energies through the parallel matched crystal system. This paper addresses a method of eliminating such unwanted energies from the imaging beam using a mismatched two crystal system to prepare the beam. The properties of this mismatched system are found along with the restrictions in applying this method to a practical DEI system.

Diffraction enhanced X-ray imaging of mammals crystalline lens

Crystalline lenses are transparent biological materials where the organization of the lens fibers can also be affected by changes at molecular level, and therefore the structure and morphology of the tissue can be correlated to the loss of transparency of the lens. In this work, internal structure of mammal lenses regarding the long-range ordering of the fibers are investigated by diffraction enhanced X-ray imaging (DEI) radiography. Moreover, DEI and absorption X-ray synchrotron radiographs for healthy and cataractous crystalline lenses are compared. Significant differences in healthy and cataractous crystalline lenses are observed.

Visualization of hydrides in titanium by means of diffraction-enhanced X-ray imaging

The diffraction-enhanced X-ray imaging technique was applied for the observation of titanium polycrystals containing titanium hydride. Hydrides in titanium were formed by annealing in 1 atm hydrogen gas and by electrolytic charging for cross-sectional observations. Although the hydrides in titanium cannot be observed by conventional radiography that utilizes absorption of X-rays, we were able to obtain a high-contrast projection image of a hydride using refraction-contrast radiography. The study shows that this is a promising new technique for non-destructive inspection of bulk material systems with only small differences between refraction indexes of the components.

Human breast cancer in vitro: matching histo-pathology with small-angle x-ray scattering and diffraction enhanced x-ray imaging

Twenty-eight human breast tumour specimens were studied with small-angle x-ray scattering (SAXS), and 10 of those were imaged by the diffraction enhanced x-ray imaging (DEI) technique. The sample diameter was 20 mm and the thickness 1 mm. Two examples of ductal carcinoma are illustrated by histology images, DEI, and maps of the collagen d-spacing and scattered intensity in the Porod regime, which characterize the SAXS patterns from collagen-rich regions of the samples. Histo-pathology reveals the cancer-invaded regions, and the maps of the SAXS parameters show that in these regions the scattering signal differs significantly from scattering by the surrounding tissue, indicating a degradation of the collagen structure in the invaded regions. The DEI images show the borders between collagen and adipose tissue and provide a co-ordinate system for tissue mapping by SAXS. In addition, degradation of the collagen structure in an invaded region is revealed by fading contrast of the DEI refraction image. The 28 samples include fresh, defrosted tissue and formalin-fixed tissue. The d-values with their standard deviations are given. In the fresh samples there is a systematic 0.76% increase of the d-value in the invaded regions, averaged over 11 samples. Only intra-sample comparisons are made for the formalin-fixed samples, and with a long fixation time, the difference in the d-value stabilizes at about 0.7%. The correspondence between the DEI images, the SAXS maps and the histo-pathology suggests that definitive information on tumour growth and malignancy is obtained by combining these x-ray methods.

P208 Biomechanics and diffraction-enhanced X-ray imaging of mechanically injured human talar cartilage

P208 Biomechanics and diffraction-enhanced X-ray imaging of mechanically injured human talar cartilage

Radiography of soft tissue of the foot and ankle with diffraction enhanced imaging.

Non-calcified tissues, including tendons, ligaments, adipose tissue and cartilage, are not visible, for any practical purposes, with conventional X-ray imaging. Therefore, any pathological changes in these tissues generally necessitate detection through magnetic resonance imaging or ultrasound technology. Until recently the development of an X-ray imaging technique that could detect both bone and soft tissues seemed unrealistic. However, the introduction of diffraction enhanced X-ray imaging (DEI) which is capable of rendering images with absorption, refraction and scatter rejection qualities has allowed detection of specific soft tissues based on small differences in tissue densities. Here we show for the first time that DEI allows high contrast imaging of soft tissues, including ligaments, tendons and adipose tissue, of the human foot and ankle.