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Ronald R. Price - One of the best experts on this subject based on the ideXlab platform.
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characterization of the phase Contrast Radiography edge enhancement effect in a cabinet x ray system
Physics in Medicine and Biology, 2006Co-Authors: Edwin F. Donnelly, David R Pickens, Kenneth G Lewis, Kristy M Wolske, Ronald R. PriceAbstract:The purpose of this study was to demonstrate that a commercially available cabinet x-ray system is capable of phase-Contrast Radiography (PC-R) and to evaluate the effect of different system parameters on the degree of edge enhancement. An acrylic plastic edge phantom was imaged at different tube potentials (25–60 kV) and in different geometries (variable object-to-detector distances, R2, at a constant source-to-detector distance, R1 + R2). In addition, the effect of noise on the perceived edge enhancement was studied as a function of exposure time. Our results show that a modest degree of phase Contrast can be achieved in an unmodified cabinet x-ray system. In addition, the particular system evaluated allowed low-noise PC-R images to be obtained with short (6 s or less) exposures. These results suggest that with appropriate geometric choices PC-R is already available to a wide range of research scientists for use in both small-animal and human-specimen experiments.
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quantification of the effect of kvp on edge enhancement index in phase Contrast Radiography
Medical Physics, 2002Co-Authors: Edwin F. Donnelly, Ronald R. PriceAbstract:This study was performed to measure the dependence of edge-enhancement in polychromatic phase-Contrast Radiography on x-ray tube operating voltage. Measurements of edge enhancement were made at tube voltages from 40 to 86 kVp using a tungstenanodex-ray tube with a nominal focal spot size of 100 micrometers. A relatively weak attenuating, sharp edge consisting of a thin lucite sheet (3 mm) in air was imaged utilizing phase-Contrast Radiography (PC-R). PC-R images were acquired at different radiographic techniques in which x-ray tube voltage was varied from 40 to 86 kVp. The image receptor was a single emulsion x-ray mammography cassette. Optical density profiles across the edge of the object were obtained using a film digitizer and edge-enhancement indices were calculated. Increasing kVp resulted in a gradual decrease of the edge-enhancement index. Even at the highest kVp (86), however, important edge-enhancement effects were evident. While there is some degradation in the edge-enhancement effect of phase-Contrast Radiography at higher kVps, the decrease from 40 to 86 kVp is relatively small (11%). Our results suggest that further investigation into the role of phase-Contrast imaging at higher kVp values for the purpose of patient dose reduction while still realizing the advantage of phase-Contrast effects for improved soft-tissue detectability is warranted.
Edwin F. Donnelly - One of the best experts on this subject based on the ideXlab platform.
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characterization of the phase Contrast Radiography edge enhancement effect in a cabinet x ray system
Physics in Medicine and Biology, 2006Co-Authors: Edwin F. Donnelly, David R Pickens, Kenneth G Lewis, Kristy M Wolske, Ronald R. PriceAbstract:The purpose of this study was to demonstrate that a commercially available cabinet x-ray system is capable of phase-Contrast Radiography (PC-R) and to evaluate the effect of different system parameters on the degree of edge enhancement. An acrylic plastic edge phantom was imaged at different tube potentials (25–60 kV) and in different geometries (variable object-to-detector distances, R2, at a constant source-to-detector distance, R1 + R2). In addition, the effect of noise on the perceived edge enhancement was studied as a function of exposure time. Our results show that a modest degree of phase Contrast can be achieved in an unmodified cabinet x-ray system. In addition, the particular system evaluated allowed low-noise PC-R images to be obtained with short (6 s or less) exposures. These results suggest that with appropriate geometric choices PC-R is already available to a wide range of research scientists for use in both small-animal and human-specimen experiments.
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quantification of the effect of kvp on edge enhancement index in phase Contrast Radiography
Medical Physics, 2002Co-Authors: Edwin F. Donnelly, Ronald R. PriceAbstract:This study was performed to measure the dependence of edge-enhancement in polychromatic phase-Contrast Radiography on x-ray tube operating voltage. Measurements of edge enhancement were made at tube voltages from 40 to 86 kVp using a tungstenanodex-ray tube with a nominal focal spot size of 100 micrometers. A relatively weak attenuating, sharp edge consisting of a thin lucite sheet (3 mm) in air was imaged utilizing phase-Contrast Radiography (PC-R). PC-R images were acquired at different radiographic techniques in which x-ray tube voltage was varied from 40 to 86 kVp. The image receptor was a single emulsion x-ray mammography cassette. Optical density profiles across the edge of the object were obtained using a film digitizer and edge-enhancement indices were calculated. Increasing kVp resulted in a gradual decrease of the edge-enhancement index. Even at the highest kVp (86), however, important edge-enhancement effects were evident. While there is some degradation in the edge-enhancement effect of phase-Contrast Radiography at higher kVps, the decrease from 40 to 86 kVp is relatively small (11%). Our results suggest that further investigation into the role of phase-Contrast imaging at higher kVp values for the purpose of patient dose reduction while still realizing the advantage of phase-Contrast effects for improved soft-tissue detectability is warranted.
Gregory B. Daniel - One of the best experts on this subject based on the ideXlab platform.
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J Vet Diagn Invest 20:656–660 (2008) Diffuse intestinal T-cell lymphosarcoma in a yellow-naped Amazon parrot (Amazona ochrocephala auropalliata)
2016Co-Authors: Marcy J. Souza, Shelley J. Newman, Cheryl B. Greenacre, James S. Avenell, Jonathan S. Wall, Jeffrey C. Phillips, Michael M. Fry, Robert L. Donnell, Gregory B. DanielAbstract:Abstract. A 10-year-old, intact, female yellow-naped Amazon parrot (Amazona ochrocephala auropalliata) was examined because of anemia, lymphocytic leukocytosis, regurgitation, and weight loss. A positive fecal occult blood and monoclonal globulinopathy were present. A distended proventriculus and diffusely thickened loops of small intestine with irregular luminal surfaces were identified with Contrast Radiography and Contrast computed tomography. A micro positron emission tomography scan was performed with 18F-fluoro-deoxyglucose. Diffuse intestinal T-cell lymphosarcoma was diagnosed based on histopathology and immunohistochemistry of full thickness small intestinal biopsies. The patient was treated with a multidrug chemotherapy protocol with little to no effect. Euthanasia was elected, and intestinal lymphosarcoma was confirmed on histopathology of necropsy intestinal samples; no other organs demonstrated neoplastic infiltration. To the authors ’ knowledge, no reports are currently available detailing the clinical presentation or diagnosis of diffuse intestinal T-cell lymphosarcoma in any avian species. Key words: Avian; immunohistochemistry; lymphosarcoma; positron emission tomography. 1 Lymphosarcoma (LSA) is the most commonly reported lymphoid neoplasm in parrots and has been reported i
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diffuse intestinal t cell lymphosarcoma in a yellow naped amazon parrot amazona ochrocephala auropalliata
Journal of Veterinary Diagnostic Investigation, 2008Co-Authors: Marcy J. Souza, Shelley J. Newman, Cheryl B. Greenacre, James S. Avenell, Jonathan S. Wall, Jeffrey C. Phillips, Michael M. Fry, Robert L. Donnell, Gregory B. DanielAbstract:A 10-year-old, intact, female yellow-naped Amazon parrot (Amazona ochrocephala auropalliata) was examined because of anemia, lymphocytic leukocytosis, regurgitation, and weight loss. A positive fecal occult blood and monoclonal globulinopathy were present. A distended proventriculus and diffusely thickened loops of small intestine with irregular luminal surfaces were identified with Contrast Radiography and Contrast computed tomography. A micro positron emission tomography scan was performed with 18 F-fluoro- deoxyglucose. Diffuse intestinal T-cell lymphosarcoma was diagnosed based on histopathology and immunohistochemistry of full thickness small intestinal biopsies. The patient was treated with a multidrug chemotherapy protocol with little to no effect. Euthanasia was elected, and intestinal lymphosarcoma was confirmed on histopathology of necropsy intestinal samples; no other organs demonstrated neoplastic infiltration. To the authors' knowledge, no reports are currently available detailing the clinical presentation or diagnosis of diffuse intestinal T-cell lymphosarcoma in any avian species.
D Korytar - One of the best experts on this subject based on the ideXlab platform.
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on the edge refraction Contrast imaging on a conventional neutron diffractometer employing dispersive double crystal monochromator
Journal of Physics: Conference Series, 2016Co-Authors: P Mikula, M Vrana, Jan Capek, D KorytarAbstract:Conventional Radiography is based on absorption effects, which depend only on the imaginary part of the refractive index. However, slits and macroscopic objects such as edges give rise to refraction and this phenomenon can be effectively used in the so called phase- Contrast imaging. In addition to the absorption Contrast in the conventional Radiography, it exploits also contributions of phase shifts induced by the propagation of a coherent neutron (or X-ray) beam through an investigated sample. The difference in real part of the refrative index between a studied detail and its vicinity results in a phase shift between the wave transmitted through and outside the detail. Due to this phase shift, the two waves interfere. However, the used radiation has to possess a sufficiently high spatial coherence permitting one to detect resulting interference pattern. In this contribution we present two simple neutron diffractometer configurations based on two bent perfect Si crystals which provide a high spatial coherence beam of sufficient intensity which could be potentially used in some phase Contrast Radiography experiments.
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edge refraction Contrast imaging on a coventional neutron diffractometer employing dispersive double crystal monochromator
Physics Procedia, 2015Co-Authors: P Mikula, M Vrana, D KorytarAbstract:Abstract Slits and macroscopic objects such as edges give rise to interference effects when a coherent neutron (or X-ray) beam propagates through an investigated sample. These phenomena are effectively used in the so called phase-Contrast imaging. In addition to the absorption Contrast in the conventional Radiography it exploits also these contributions from the induced phase shifts. However, the used radiation has to possess a sufficiently high spatial coherence. In this contribution we present a special neutron diffractometer performance (in two alternatives A and B) based on two bent perfect Si crystals which provides a high spatial coherence beam of sufficient intensity which could be potentially used in some phase Contrast Radiography experiments.
Andrew W Stevenson - One of the best experts on this subject based on the ideXlab platform.
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phase Contrast imaging using polychromatic hard x rays
Nature, 1996Co-Authors: S W Wilkins, Timur E Gureyev, A Pogany, Andrew W StevensonAbstract:IN conventional Radiography, X-rays which pass through an object along different paths are differentially absorbed, and the intensity pattern of the emerging beam records the distribution of absorbing materials within the sample. An alternative approach is phase-Contrast Radiography, which instead records variations of the phase of the emerging radiation. Such an approach offers improved Contrast sensitivity, especially when imaging weakly absorbing samples. Unfortunately, current phase-Contrast imaging techniques1–11 generally require highly monochromatic plane-wave radiation and sophisticated X-ray optics, so their use is greatly restricted. Here we describe and demonstrate a simplified scheme for phase-Contrast imaging based on an X-ray source having high spatial (but essentially no chromatic) coherence. The method is compatible with conventional polychromatic micro-focus X-ray tube sources, is well suited to large areas of irradiation, can operate with a lower absorbed dose than traditional X-ray imaging techniques, and should find broad application in clinical, biological and industrial settings.