The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
S W Wilkins - One of the best experts on this subject based on the ideXlab platform.
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x ray Phase Contrast microscopy and microtomography
Optics Express, 2003Co-Authors: Sheridan C Mayo, Timothy J Davis, Timur E Gureyev, Peter Miller, David M Paganin, A Pogany, Andrew W Stevenson, S W WilkinsAbstract:In-line Phase Contrast enables weakly absorbing specimens to be imaged successfully with x-rays, and greatly enhances the visibility of fine scale structure in more strongly absorbing specimens. This type of Phase Contrast requires a spatially coherent beam, a condition that can be met by a microfocus x-ray source. We have developed an x-ray microscope, based on such a source, which is capable of high resolution Phase-Contrast imaging and tomography. Phase retrieval enables quantitative information to be recovered from Phase-Contrast microscope images of homogeneous samples of known composition and density, and improves the quality of tomographic reconstructions.
Sheridan C Mayo - One of the best experts on this subject based on the ideXlab platform.
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x ray Phase Contrast microscopy and microtomography
Optics Express, 2003Co-Authors: Sheridan C Mayo, Timothy J Davis, Timur E Gureyev, Peter Miller, David M Paganin, A Pogany, Andrew W Stevenson, S W WilkinsAbstract:In-line Phase Contrast enables weakly absorbing specimens to be imaged successfully with x-rays, and greatly enhances the visibility of fine scale structure in more strongly absorbing specimens. This type of Phase Contrast requires a spatially coherent beam, a condition that can be met by a microfocus x-ray source. We have developed an x-ray microscope, based on such a source, which is capable of high resolution Phase-Contrast imaging and tomography. Phase retrieval enables quantitative information to be recovered from Phase-Contrast microscope images of homogeneous samples of known composition and density, and improves the quality of tomographic reconstructions.
Franz Pfeiffer - One of the best experts on this subject based on the ideXlab platform.
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A theoretical framework for comparing noise characteristics of spectral, differential Phase-Contrast and spectral differential Phase-Contrast x-ray imaging.
Physics in Medicine and Biology, 2020Co-Authors: Korbinian Mechlem, Julia Herzen, Thorsten Sellerer, Manuel Viermetz, Franz PfeifferAbstract:Spectral and grating-based differential Phase-Contrast X-ray imaging are two emerging technologies that offer additional information compared with conventional attenuation-based X-ray imaging. In the case of spectral imaging, energy-resolved measurements allow the generation of material-specific images by exploiting differences in the energy-dependent attenuation. Differential Phase-Contrast imaging uses the Phase shift that an X-ray wave exhibits when traversing an object as Contrast generation mechanism. Recently, we have investigated the combination of these two imaging techniques (spectral differential Phase-Contrast imaging) and demonstrated potential advantages compared with spectral imaging. In this work, we present a noise analysis framework that allows the prediction of (co-) variances and noise power spectra for all three imaging methods. Moreover, the optimum acquisition parameters for a particular imaging task can be determined. We use this framework for a performance comparison of all three imaging methods. The comparison is focused on (projected) electron density images since they can be calculated with all three imaging methods. Our study shows that spectral differential Phase-Contrast imaging enables the calculation of electron density images with strongly reduced noise levels compared with the other two imaging methods for a large range of clinically relevant pixel sizes. In Contrast to conventional differential Phase-Contrast imaging, there are no long-range noise correlations for spectral differential Phase-Contrast imaging. This means that excessive low frequency noise can be avoided. We confirm the analytical predictions by numerical simulations.
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A theoretical framework to compare noise characteristics of spectral, differential Phase-Contrast and spectral differential Phase-Contrast imaging
arXiv: Medical Physics, 2019Co-Authors: Korbinian Mechlem, Julia Herzen, Thorsten Sellerer, Manuel Viermetz, Franz PfeifferAbstract:Spectral and grating-based differential Phase-Contrast X-ray imaging are two emerging technologies that offer additional information compared to conventional attenuation-based X-ray imaging. In the case of spectral imaging, energy-resolved measurements allow the generation of material-specific images by exploiting differences in the energy-dependent attenuation. Differential Phase-Contrast imaging uses the Phase shift that an X-ray wave exhibits when traversing an object as Contrast generation mechanism. Recently, we have investigated the combination of these two imaging techniques (spectral differential Phase-Contrast imaging) and demonstrated potential advantages compared to spectral imaging. In this work, we present a noise analysis framework that allows the prediction of (co-) variances and noise power spectra for all three imaging methods. Moreover, the optimum acquisition parameters for a particular imaging task can be determined. We use this framework for a performance comparison of all three imaging methods. The comparison is focused on (projected) electron density images since they can be calculated with all three imaging methods. Our study shows that spectral differential Phase-Contrast imaging enables the calculation of electron density images with strongly reduced noise levels compared to the other two imaging methods for a large range of clinically relevant pixel sizes. In Contrast to conventional differential Phase-Contrast imaging, there are no long-ranging noise correlations for spectral differential Phase-Contrast imaging. This means that excessive low frequency noise can be avoided. We confirm the analytical predictions by numerical simulations.
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Spectral Differential Phase Contrast X-ray Radiography
IEEE Transactions on Medical Imaging, 1Co-Authors: Korbinian Mechlem, Julia Herzen, Thorsten Sellerer, Manuel Viermetz, Franz PfeifferAbstract:We investigate the combination of two emerging X-ray imaging technologies, namely spectral imaging and differential Phase Contrast imaging. By acquiring spatially and temporally registered images with several different X-ray spectra, spectral imaging can exploit differences in the energy-dependent attenuation to generate material selective images. Differential Phase Contrast imaging uses an entirely different Contrast generation mechanism: The Phase shift that an X-ray wave exhibits when traversing an object. As both methods can determine the (projected) electron density, we propose a novel material decomposition algorithm that uses the spectral and the Phase Contrast information simultaneously. Numerical experiments show that the combination of these two imaging techniques benefits from the strengths of the individual methods while the weaknesses are mitigated: Quantitatively accurate basis material images are obtained and the noise level is strongly reduced, compared to conventional spectral X-ray imaging.
Andrew W Stevenson - One of the best experts on this subject based on the ideXlab platform.
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x ray Phase Contrast microscopy and microtomography
Optics Express, 2003Co-Authors: Sheridan C Mayo, Timothy J Davis, Timur E Gureyev, Peter Miller, David M Paganin, A Pogany, Andrew W Stevenson, S W WilkinsAbstract:In-line Phase Contrast enables weakly absorbing specimens to be imaged successfully with x-rays, and greatly enhances the visibility of fine scale structure in more strongly absorbing specimens. This type of Phase Contrast requires a spatially coherent beam, a condition that can be met by a microfocus x-ray source. We have developed an x-ray microscope, based on such a source, which is capable of high resolution Phase-Contrast imaging and tomography. Phase retrieval enables quantitative information to be recovered from Phase-Contrast microscope images of homogeneous samples of known composition and density, and improves the quality of tomographic reconstructions.
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Phase-Contrast radiography.
Radiographics, 1998Co-Authors: A Pogany, Andrew W Stevenson, Steve WilkinsAbstract:For the past 100 years, the paradigm for radiography has been premised on absorption as the sole means of Contrast formation and on ray optics as the basis for image interpretation. A new conceptual approach to radiography has been developed that includes Phase (ie, refractive) Contrast and requires wave optics for proper treatment. This new approach greatly increases the amount of information that can be obtained with radiographic techniques and is particularly well suited to the imaging of soft tissue and of very small features in biologic samples. A key feature of the present technique of Phase-Contrast radiography is the use of a microfocus x-ray source about an order of magnitude (< or = 20 microm) smaller than that used in conventional radiography. Phase-Contrast radiography offers a number of improvements over conventional radiography in a clinical setting, especially in soft-tissue imaging. These improvements include increased Contrast resulting in improved visualization of anatomic detail, reduce...
A Pogany - One of the best experts on this subject based on the ideXlab platform.
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x ray Phase Contrast microscopy and microtomography
Optics Express, 2003Co-Authors: Sheridan C Mayo, Timothy J Davis, Timur E Gureyev, Peter Miller, David M Paganin, A Pogany, Andrew W Stevenson, S W WilkinsAbstract:In-line Phase Contrast enables weakly absorbing specimens to be imaged successfully with x-rays, and greatly enhances the visibility of fine scale structure in more strongly absorbing specimens. This type of Phase Contrast requires a spatially coherent beam, a condition that can be met by a microfocus x-ray source. We have developed an x-ray microscope, based on such a source, which is capable of high resolution Phase-Contrast imaging and tomography. Phase retrieval enables quantitative information to be recovered from Phase-Contrast microscope images of homogeneous samples of known composition and density, and improves the quality of tomographic reconstructions.
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Phase-Contrast radiography.
Radiographics, 1998Co-Authors: A Pogany, Andrew W Stevenson, Steve WilkinsAbstract:For the past 100 years, the paradigm for radiography has been premised on absorption as the sole means of Contrast formation and on ray optics as the basis for image interpretation. A new conceptual approach to radiography has been developed that includes Phase (ie, refractive) Contrast and requires wave optics for proper treatment. This new approach greatly increases the amount of information that can be obtained with radiographic techniques and is particularly well suited to the imaging of soft tissue and of very small features in biologic samples. A key feature of the present technique of Phase-Contrast radiography is the use of a microfocus x-ray source about an order of magnitude (< or = 20 microm) smaller than that used in conventional radiography. Phase-Contrast radiography offers a number of improvements over conventional radiography in a clinical setting, especially in soft-tissue imaging. These improvements include increased Contrast resulting in improved visualization of anatomic detail, reduce...
