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X ray phase contrast

Jiangkun Liu, Weixing Cai, Ruola Ning
Grating-based differential phase contrast (DPC) imaging enables the use of a hospital-grade X-ray tube, but compromises the image quality due to insufficiently coherent illumination. In this research, a bench-top DPC cone beam CT (DPC-CBCT) was systematically evaluated and compared with the traditional attenuation-based CBCT in terms of contrast to noise ratio, noise property, and contrast resolution through phantom studies. In order to evaluate DPC-CBCT for soft tissue imaging, breast specimen and small animal studies were carried out...
November 30, 2016: Journal of X-ray Science and Technology
Jan Plsek, Petr Kovaricek, Vaclav Vales, Martin Kalbac
Tuning the local reactivity of graphene is a subject of paramount importance. Among the available strategies, the activation/passivation of graphene by copper substrate is very promising, because it enables to influence the properties of graphene without any transfer procedure as graphene can be grown directly on copper. Here, we demonstrate that the reactivity of graphene towards fluorination is strongly influenced by the face of the surface of the copper substrate. We probed graphene on the copper foil with identified grain orientations...
December 2, 2016: Chemistry: a European Journal
Huifang Xu, Shiyun Jin, Bruce C Noll
Plagioclase feldspars are the most abundant mineral in the Earth's crust. Intermediate plagioclase feldspars commonly display incommensurately modulated or aperiodic structures. Z-contrast images show both Ca-Na ordering and density modulation. The local structure of lamellae domains has I1-like symmetry. The neighboring lamellae domains are in an inversion twinning relationship. With a state-of-the-art X-ray diffraction unit, second-order satellite reflections (f-reflections) are observed for the first time in andesine (An45), a Na-rich e-plagioclase...
December 1, 2016: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
A-L Robisch, J Wallentin, A Pacureanu, P Cloetens, T Salditt
We have performed near-field x-ray imaging with simultaneous object and probe reconstruction. By an advanced ptychographic algorithm based on longitudinal and lateral translations, full-field images of nanoscale objects are reconstructed with quantitative contrast values, along with the extended wavefronts used to illuminate the objects. The imaging scheme makes idealizing assumptions on the probe obsolete, and efficiently disentangles phase shifts related to the object from the imperfections in the illumination...
December 1, 2016: Optics Letters
Tunhe Zhou, Marie-Christine Zdora, Irene Zanette, Jenny Romell, Hans M Hertz, Anna Burvall
Speckle-based x-ray phase-contrast imaging has drawn increasing interest in recent years as a simple, multimodal, cost-efficient, and laboratory-source adaptable method. We investigate its noise properties to help further optimization on the method and further comparison with other phase-contrast methods. An analytical model for assessing noise in a differential phase signal is adapted from studies on the digital image correlation technique in experimental mechanics and is supported by simulations and experiments...
December 1, 2016: Optics Letters
Justin A R Lang, James T Pearson, Corinna Binder-Heschl, Megan J Wallace, Melissa L Siew, Marcus J Kitchen, Arjan B Te Pas, Robert A Lewis, Graeme R Polglase, Mikiyasu Shirai, Stuart B Hooper
Air entry into the lungs at birth triggers major cardiovascular changes, including a large increase in pulmonary blood flow (PBF) that is not spatially related to regional lung aeration. To investigate the possible underlying role of a vagally-mediated stimulus, we used simultaneous phase-contrast X-ray imaging and angiography in near-term (30 days of gestation) vagotomised (n = 15) or sham-operated (n = 15) rabbit kittens. Rabbits were imaged before ventilation, when one lung was ventilated (unilateral) with 100% nitrogen (N2 ), air or 100% oxygen (O2 ), before all kittens were switched to unilateral ventilation in air, then ventilation of both lungs using air...
November 30, 2016: Journal of Physiology
Yukihiro Kaneko, Gen Shinohara, Masato Hoshino, Hiroyuki Morishita, Kiyozo Morita, Yoshihiro Oshima, Masashi Takahashi, Naoto Yagi, Yutaka Okita, Takuro Tsukube
Structural examination of human heart specimens at the microscopic level is a prerequisite for understanding congenital heart diseases. It is desirable not to destroy or alter the properties of such specimens because of their scarcity. However, many of the currently available imaging techniques either destroy the specimen through sectioning or alter the chemical and mechanical properties of the specimen through staining and contrast agent injection. As a result, subsequent studies may not be possible. X-ray phase-contrast tomography is an imaging modality for biological soft tissues that does not destroy or alter the properties of the specimen...
November 30, 2016: Pediatric Cardiology
Huiqiang Liu, Xuewen Ji, Li Sun, Tiqiao Xiao, Honglan Xie, Yanan Fu, Yuan Zhao, Wenya Liu, Xueliang Zhang, Renyong Lin
Propagation-based phase-contrast computed tomography (PPCT) utilizes highly sensitive phase-contrast technology applied to X-ray micro-tomography, especially with the extensive use of synchrotron radiation (SR). Performing phase retrieval (PR) on the acquired angular projections can enhance image contrast and enable quantitative imaging. We employed the combination of SR-PPCT and PR for the histopathological evaluation of hepatic alveolar echinococcosis (HAE) disease and demonstrated the validity and superiority of PR-based SR-PPCT...
November 29, 2016: Scientific Reports
David Macindoe, Marcus J Kitchen, Sarah C Irvine, Andreas Fouras, Kaye S Morgan
X-ray phase contrast enables weakly-attenuating structures to be imaged, with bright synchrotron sources adding the ability to capture time sequences and analyse sample dynamics. Here, we describe the translation of dynamical differential phase contrast imaging from the synchrotron to a compact x-ray source, in order to achieve this kind of time sequence imaging in the laboratory. We formulate broadly-applicable set-up guidelines for the single-grid, single-exposure imaging technique using a divergent source, exploring the experimental factors that restrict set-up size, imaging sensitivity and sample size...
December 21, 2016: Physics in Medicine and Biology
Paul C Diemoz, Alberto Bravin, Anikó Sztrókay-Gaul, Marie Ruat, Susanne Grandl, Doris Mayr, Sigrid Auweter, Alberto Mittone, Emmanuel Brun, Cyril Ponchut, Maximilian F Reiser, Paola Coan, Alessandro Olivo
Since the breast is one of the most radiosensitive organs, mammography is arguably the area where lowering radiation dose is of the uttermost importance. Phase-based x-ray imaging methods can provide opportunities in this sense, since they do not require x-rays to be stopped in tissue for image contrast to be generated. Therefore, x-ray energy can be considerably increased compared to those usually exploited by conventional mammography. In this article we show how a novel, optimized approach can lead to considerable dose reductions...
December 21, 2016: Physics in Medicine and Biology
Zhenluan Xue, Zhigao Yi, Xiaolong Li, Youbin Li, Mingyang Jiang, Hongrong Liu, Songjun Zeng
In this work, we demonstrated multifunctional NaYbF4: Tm(3+)/Gd(3+) upconversion (UC) nanorods (UCNRs) with near-infrared (NIR)-to-NIR emission and controlled phase and size for UC optical and T1/T2 dual-weighted magnetic resonance (MR) imaging-guided small tumor detection and tri-modal bioimaging. Cell toxicity and post-injection histology results revealed that our designed UCNRs present low biotoxicity and good biocompatibility in living animals. Real-time tracking based on UCNRs in living mice demonstrated that the UCNRs were mainly accumulated in the reticuloendothelial system (RES) and excreted through the hepatic pathway...
November 17, 2016: Biomaterials
V H Tran, P Głuchowski, A Łukowiak, W Stre Combining Cedilla K
Undoped and Ag-doped TiO2 ceramics have been prepared at temperatures between 500-1000 °C and under pressures up to 8 GPa. Their crystal structures and physical properties were investigated by means of EDX, SEM, TEM, X-ray powder diffraction, and magnetization M, specific heat Cp and electrical resistance ρ measurements. It is found that the anatase-structured As-cast powder transforms into rutile and columbite-type at 500 °C and 5.5 GPa. The stabilization of the latter phase is fulfilled under a pressure of 8 GPa and at temperatures above 800 °C...
December 1, 2016: Nanoscale
Bartłomiej Włodarczyk
This article considers the problem of recovering edge-illumination x-ray phase contrast (EIXPC) images from a set of potentially Poisson noisy projection measurements. The authors cast a recovery as a sparse regularization problem based on Anscombe multiscale variance stabilizing transform (MS-VST) with fast discrete curvelet transform which was applied to simulated edge-illumination x-ray phase contrast images. For accurate modelling, the noise characteristics of the EIXPCi data are used to determine the relative importance of each projection...
November 11, 2016: Journal of X-ray Science and Technology
M Marschner, L Birnbacher, K Mechlem, W Noichl, A Fehringer, M Willner, K Scherer, J Herzen, P B Noël, F Pfeiffer
In this article, we report on a novel acquisition scheme for time- and dose-saving retrieval of dark-field data in grating-based phase-contrast imaging. In comparison to currently available techniques, the proposed approach only requires two phase steps. More importantly, our method is capable of accurately retrieving the dark-field signal where conventional approaches fail, for instance in the case of very low photon statistics. Finally, we successfully extend two-shot dark-field imaging to tomographic investigations, by implementing an iterative reconstruction with appropriate weights...
November 14, 2016: Optics Express
Oliver Preusche
A novel way to build arrays of X-ray lenslets is proposed for use in medical imaging, in particular for X-ray phase contrast imaging. Focusing on Talbot-Lau interferometers, this work is about patient dose reduction, especially for design energies above 50 keV. A low dose poses a fabrication problem, because it requires an analyzer grating which is both fine and high: It has to be fine for a good angular sensitivity. It has to be high to absorb well. However, gratings can currently be built either fine or high...
November 14, 2016: Optics Express
Fucai Zhang, Bo Chen, Graeme R Morrison, Joan Vila-Comamala, Manuel Guizar-Sicairos, Ian K Robinson
Phase retrieval is a long-standing problem in imaging when only the intensity of the wavefield can be recorded. Coherent diffraction imaging is a lensless technique that uses iterative algorithms to recover amplitude and phase contrast images from diffraction intensity data. For general samples, phase retrieval from a single-diffraction pattern has been an algorithmic and experimental challenge. Here we report a method of phase retrieval that uses a known modulation of the sample exit wave. This coherent modulation imaging method removes inherent ambiguities of coherent diffraction imaging and uses a reliable, rapidly converging iterative algorithm involving three planes...
November 18, 2016: Nature Communications
Andris Bukejs, Michael Schmitt
Based on a single well-preserved specimen from Eocene Baltic amber, Lilioceris groehnisp. n. is described and illustrated using phase-contrast X-ray microtomography. It is the first described species of Criocerinae (Coleoptera: Chrysomelidae) from Baltic amber. A check-list of fossil Criocerinae is provided. Placement of Crioceris pristiana (Germar, 1813) is discussed, this species is removed from Criocerinae and placed in Coleoptera incertae sedis.
2016: ZooKeys
Paul C Diémoz, Fabio A Vittoria, Charlotte K Hagen, Marco Endrizzi, Paola Coan, Alberto Bravin, Ulrich H Wagner, Christoph Rau, Ian K Robinson, Alessandro Olivo
PURPOSE: Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has been under development at University College London in recent years, and has shown great potential for both laboratory and synchrotron applications. In this work, we propose a new acquisition and processing scheme. Contrary to existing retrieval methods for EI, which require as input two images acquired in different setup configurations, the proposed approach can retrieve an approximate map of the X-ray phase from a single image, thus significantly simplifying the acquisition procedure and reducing data collection times...
November 8, 2016: Physica Medica: PM
Anna Jerve, Qingming Qu, Sophie Sanchez, Henning Blom, Per Erik Ahlberg
Lophosteus superbus is one of only a handful of probable stem-group osteichthyans known from the fossil record. First collected and described in the late 19th century from the upper Silurian Saaremaa Cliff locality in Estonia, it is known from a wealth of disarticulated scales, fin spines, and bone fragments. In this study we provide the first description of the morphology and paleohistology of a fin spine and scale from Lophosteus using virtual thin sections and 3D reconstructions that were segmented using phase-contrast synchrotron X-ray microtomography...
2016: PeerJ
Kaye S Morgan, Timothy C Petersen, Martin Donnelley, Nigel Farrow, David W Parsons, David M Paganin
The detection, localisation and characterisation of stationary and singular points in the phase of an X-ray wavefield is a challenge, particularly given a time-evolving field. In this paper, the associated difficulties are met by the single-grid, single-exposure X-ray phase contrast imaging technique, enabling direct measurement of phase maxima, minima, saddle points and vortices, in both slowly varying fields and as a means to visualise weakly-attenuating samples that introduce detailed phase variations to the X-ray wavefield...
October 17, 2016: Optics Express
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