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Phase retrieval and differential phase-contrast imaging with low-brilliance X-ray sources,
- Nature Physics
, 2006
"... X -ray radiographic absorption imaging is an invaluable tool in medical diagnostics and materials science. For biological tissue samples, polymers or fibre composites, however, the use of conventional X-ray radiography is limited due to their weak absorption. This is resolved at highly brilliant X- ..."
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Cited by 49 (11 self)
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X -ray radiographic absorption imaging is an invaluable tool in medical diagnostics and materials science. For biological tissue samples, polymers or fibre composites, however, the use of conventional X-ray radiography is limited due to their weak absorption. This is resolved at highly brilliant X-ray synchrotron or micro-focus sources by using phase-sensitive imaging methods to improve the contrast 1,2 . However, the requirements of the illuminating radiation mean that hard-X-ray phase-sensitive imaging has until now been impractical with more readily available X-ray sources, such as X-ray tubes. In this letter, we report how a setup consisting of three transmission gratings can efficiently yield quantitative differential phase-contrast images with conventional X-ray tubes. In contrast with existing techniques, the method requires no spatial or temporal coherence, is mechanically robust, and can be scaled up to large fields of view. Our method provides all the benefits of contrast-enhanced phase-sensitive imaging, but is also fully compatible with conventional absorption radiography. It is applicable to X-ray medical imaging, industrial non-destructive testing, and to other low-brilliance radiation, such as neutrons or atoms. In conventional X-ray imaging, contrast is obtained through the differences in the absorption cross-section of the constituents of the object. The technique yields excellent results where highly absorbing structures such as bones are embedded in a matrix of relatively weakly absorbing material, for example the surrounding tissue of the human body. However, in cases where different forms of tissue with similar absorption cross-sections are under investigation (for example, mammography or angiography), the X-ray absorption contrast is relatively poor. Consequently, differentiating pathologic from non-pathologic tissue in an absorption radiograph obtained with a current hospital-based X-ray system remains practically impossible for certain tissue compositions. To overcome these limitations, several methods to generate radiographic contrast from the phase shift of X-rays passing through the sample have been investigated 3-13 . They can be classified into interferometric methods 3,4 , techniques using an analyser 5-7 and free-space propagation methods In this letter, we demonstrate how an alternative approach using a grating-based differential phase-contrast (DPC) setup can be efficiently used to retrieve quantitative phase images with polychromatic X-ray sources of low brilliance. Similarly to equivalent approaches in the visible light
High-resolution X-ray computed tomography of an extant new
"... Donuea (Araneae: Liocranidae) species in Madagascan copal ..."
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Donuea (Araneae: Liocranidae) species in Madagascan copal
Revealing the 3D internal structure of natural polymer microcomposites using X-ray ultra microtomography
"... Summary Properties of composite materials are directly affected by the spatial arrangement of reinforcement and matrix. In this research, partially hydrolysed cellulose microcrystals were used to fabricate polycaprolactone microcomposites. The spatial distribution of cellulose microcrystals was cha ..."
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Summary Properties of composite materials are directly affected by the spatial arrangement of reinforcement and matrix. In this research, partially hydrolysed cellulose microcrystals were used to fabricate polycaprolactone microcomposites. The spatial distribution of cellulose microcrystals was characterized by a newly developed technique of X-ray ultra microscopy and microtomography. The phase and absorption contrast imaging of X-ray ultra microscopy revealed twodimensional and three-dimensional information on CMC distribution in polymer matrices. The highest contrast and flux (signal-to-noise ratio) were obtained using vanadium foil targets with the accelerating voltage of 30 keV and beam current of >200 nA. The spatial distribution of cellulose microcrystals was correlated to the mechanical properties of the microcomposites. It was observed that heterogeneous distribution and clustering of cellulose microcrystals resulted in degradation of tensile strength and elastic modulus of composites. The utilization of X-ray ultra microscopy can open up new opportunities for composite researchers to explore the internal structure of microcomposites. X-ray ultra microscopy sample preparation is relatively simple in comparison to transmission electron microscopy and the spatial information is gathered at much larger scale.
Computed tomography with linear shift-invariant optical systems
"... Optical systems capable of three-dimensional transmission imaging are considered; these systems employ a conventional tomographic setup with an added linear shift-invariant optical system between the sample and the detector. A theoretical analysis is presented of image formation and sample reconstru ..."
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Optical systems capable of three-dimensional transmission imaging are considered; these systems employ a conventional tomographic setup with an added linear shift-invariant optical system between the sample and the detector. A theoretical analysis is presented of image formation and sample reconstruction in such systems, examples of which include diffraction tomography and phase-contrast tomography with the use of analyzer crystals. An example is introduced in which the image is obtained by scanning the beam along the line orthogonal to the optic axis and to the axis of rotation with a one-dimensional slit or grating parallel to the rotation axis. We show that under certain conditions the proposed system may allow quantitative local (regionof-interest)
Phase Contrast Imaging in Laboratory
"... Since Roentgen's discovery of X-rays, just over a century ago, the vast majority of radiographs have been acquired and interpreted on the basis of absorption contrast. The recent development of X-ray phase contrast imaging techniques opens up a new opportunity especially for weakly-absorbing ob ..."
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Since Roentgen's discovery of X-rays, just over a century ago, the vast majority of radiographs have been acquired and interpreted on the basis of absorption contrast. The recent development of X-ray phase contrast imaging techniques opens up a new opportunity especially for weakly-absorbing objects. Spatial and temporal coherence of X-ray synchrotron radiation permits to realize phase contrast imaging with ideal conditions. But it is possible to set up phase contrast imaging in laboratory. Laboratory phase contrast imaging can provide new solutions in an industrial context. The aim of this paper is to present the different solutions to perform phase contrast imaging in laboratory: − classical micro focus X-ray tube, − X-ray ultra microscope (XuM) developed by an Australian team − table top synchrotron developed by a Japanese team, − multilayer, − polycapillary.
Experimental Mechanics (Special issue on DIC) manuscript No. (will be inserted by the editor) Projection savings in CT-based Digital Volume Correlation
"... Abstract The measurement of three dimensional displacement fields from tomo-graphic image registration, or Digital Volume Correlation, usually operates over two volumes that have been reconstructed from numerous radiographs at the elementary voxel scale. It is shown herein that a single “reference ” ..."
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Abstract The measurement of three dimensional displacement fields from tomo-graphic image registration, or Digital Volume Correlation, usually operates over two volumes that have been reconstructed from numerous radiographs at the elementary voxel scale. It is shown herein that a single “reference ” (i.e., fully reconstructed) volume, and very few radiographs of the deformed configuration may be sufficient to evaluate 3D displacement fields. The proposed algorithm can reduce the needed num-ber of projection data by several orders of magnitude as shown on an experimental data set.
