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X ray phase contrast

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https://www.readbyqxmd.com/read/28430991/development-toward-high-resolution-x-ray-phase-imaging
#1
Atsushi Momose
Since the 1990s, the use of X-ray phase contrast has been extensively studied for imaging weakly absorbing objects consisting of low-Z elements such as biological soft tissues and polymers. The development of X-ray microscopy was also progressing during this time, although absorption contrast was only available. It was straightforward and important to develop phase-contrast X-ray microscopy. One characteristic in the development is that quantitative phase measurement is possible through the acquisition of phase-contrast images under a specific procedure, thanks to digital X-ray image detectors...
April 18, 2017: Microscopy
https://www.readbyqxmd.com/read/28421602/the-qualitative-f-ratio-method-applied-to-electron-channelling-induced-x-ray-imaging-with-an-annular-silicon-drift-detector-in-a-scanning-electron-microscope-in-the-transmission-mode
#2
Nicolas Brodusch, Raynald Gauvin
Electron channelling is known to affect the x-ray production when an accelerated electron beam is applied to a crystalline material and is highly dependent on the local crystal orientation. This effect, unless very long counting time are used, is barely noticeable on x-ray energy spectra recorded with conventional silicon drift detectors (SDD) located at a small elevation angle. However, the very high count rates provided by the new commercially available annular SDDs permit now to observe this effect routinely and may, in some circumstances, hide the true elemental x-ray variations due to the local true specimen composition...
April 18, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28419456/time-lapse-lab-based-x-ray-nano-ct-study-of-corrosion-damage
#3
R S Bradley, Y Liu, T L Burnett, X Zhou, S B Lyon, P J Withers, A Gholinia, T Hashimoto, D Graham, S R Gibbon, B Hornberger
An experimental protocol (workflow) has been developed for time-lapse x-ray nanotomography (nano-CT) imaging of environmentally driven morphological changes to materials. Two case studies are presented. First, the leaching of nanoparticle corrosion inhibitor pigment from a polymer coating was followed over 14 days, while in the second case the corrosion damage to an AA2099 aluminium alloy was imaged over 12 hours. The protocol includes several novel aspects relevant to nano-CT with the use of a combination of x-ray absorption and phase contrast data to provide enhanced morphological and composition information, and hence reveal the best information to provide new insights into the changes of different phases over time...
April 17, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28417632/evidence-of-multiple-sorption-modes-in-layered-double-hydroxides-using-mo-as-structural-probe
#4
Bin Ma, Alejandro Fernandez-Martinez, Sylvain Grangeon, Christophe Tournassat, Nathaniel Findling, Francis Claret, Ayumi Koishi, Nicolas C M Marty, Delphine Tisserand, Sarah Bureau, Eduardo Salas-Colera, Erik Elkaim, Carlo Marini, Laurent Charlet
Layered double hydroxides (LDHs) have been considered as effective phases for the remediation of aquatic environments, to remove anionic contaminants mainly through anion exchange mechanisms. Here, a combination of batch isotherm experiments and X-ray techniques was used to examine molybdate (MoO42-) sorption mechanisms on CaAl LDHs with increasing loadings of molybdate. Advanced modelling of aqueous data shows that the sorption isotherm can be interpreted by three retention mechanisms, including two types of edge sites complexes, interlayer anion exchange, and CaMoO4 precipitation...
April 18, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28399114/lung-hypoplasia-in-newborn-rabbits-with-a-diaphragmatic-hernia-affects-pulmonary-ventilation-but-not-perfusion
#5
Andreas W Flemmer, Marta Thio, Megan J Wallace, Katie Lee, K Marcus J Kitchen, Lauren Kerr, Charles C Roehr, Andreas Fouras, Richard Carnibella, Jaccques J Jani, Philip DeKoninck, Arjan B tePas, James T Pearson, Stuart B Hooper
BACKGROUND: A congenital diaphragmatic hernia can result in severe lung hypoplasia that increases the risk of morbidity and mortality after birth, but little is known about the cardiorespiratory transition at birth. METHODS: Using phase contrast X-ray imaging and angiography, we examined the cardiorespiratory transition at birth in rabbit kittens with diaphragmatic hernias (DH). Surgery was performed on pregnant New Zealand white rabbits (n=18) at 25 days gestation to induce a left-sided DH...
April 11, 2017: Pediatric Research
https://www.readbyqxmd.com/read/28384187/target-localization-of-3d-versus-4d-cone-beam-computed-tomography-in-lipiodol-guided-stereotactic-radiotherapy-of-hepatocellular-carcinomas
#6
Mark Chan, Chi Leung Chiang, Venus Lee, Steven Cheung, Ronnie Leung, Matthew Wong, Frankle Lee, Oliver Blanck
BACKGROUND: Aim of this study was to comparatively evaluate the accuracy of respiration-correlated (4D) and uncorrelated (3D) cone beam computed tomography (CBCT) in localizing lipiodolized hepatocellular carcinomas during stereotactic body radiotherapy (SBRT). METHODS: 4D-CBCT scans of eighteen HCCs were acquired during free-breathing SBRT following trans-arterial chemo-embolization (TACE) with lipiodol. Approximately 1320 x-ray projections per 4D-CBCT were collected and phase-sorted into ten bins...
2017: PloS One
https://www.readbyqxmd.com/read/28382313/geometric-calibration-and-correction-for-a-lens-coupled-detector-in-x-ray-phase-contrast-imaging
#7
Alex George, Peter Y Chen, Alejandro Morales-Martinez, Alireza Panna, Andrew A Gomella, Eric E Bennett, Han Wen
A lens-coupled x-ray camera with a tilted phosphor collects light emission from the x-ray illuminated (front) side of phosphor. Experimentally, it has been shown to double x-ray photon capture efficiency and triple the spatial resolution along the phosphor tilt direction relative to the same detector at normal phosphor incidence. These characteristics benefit grating-based phase-contrast methods, where linear interference fringes need to be clearly resolved. However, both the shallow incident angle on the phosphor and lens aberrations of the camera cause geometric distortions...
January 2017: Journal of Medical Imaging
https://www.readbyqxmd.com/read/28380987/sensitivity-based-optimization-for-the-design-of-a-grating-interferometer-for-clinical-x-ray-phase-contrast-mammography
#8
Carolina Arboleda, Zhentian Wang, Thomas Koehler, Gerhard Martens, Udo Van Stevendaal, Matthias Bartels, Pablo Villanueva-Perez, Ewald Roessl, Marco Stampanoni
An X-ray grating interferometer (GI) suitable for clinical mammography must comply with quite strict dose, scanning time and geometry limitations, while being able to detect tumors, microcalcifications and other abnormalities. Such a design task is not straightforward, since obtaining optimal phase-contrast and dark-field signals with clinically compatible doses and geometrical constraints is remarkably challenging. In this work, we present a wave propagation based optimization that uses the phase and dark-field sensitivities as figures of merit...
March 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28379851/detectability-comparison-between-a-high-energy-x-ray-phase-sensitive-and-mammography-systems-in-imaging-phantoms-with-varying-glandular-adipose-ratios
#9
Muhammad U Ghani, Molly D Wong, Di Wu, Bin Zheng, Laurie L Fajardo, Aimin Yan, Janis Fuh, Xizeng Wu, Hong Liu
The objective of this study was to demonstrate the potential benefits of using high energy x-rays in comparison with the conventional mammography imaging systems for phase sensitive imaging of breast tissues with varying glandular-adipose ratios. This study employed two modular phantoms simulating the glandular (G) and adipose (A) breast tissue composition in 50 G-50 A and 70 G-30 A percentage densities. Each phantom had a thickness of 5 cm with a contrast detail test pattern embedded in the middle. For both phantoms, the phase contrast images were acquired using a micro-focus x-ray source operated at 120 kVp and 4...
April 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28364648/retardation-of-uranium-and-thorium-by-a-cementitious-backfill-developed-for-radioactive-waste-disposal
#10
M Felipe-Sotelo, J Hinchliff, L P Field, A E Milodowski, O Preedy, D Read
The solubility of uranium and thorium has been measured under the conditions anticipated in a cementitious, geological disposal facility for low and intermediate level radioactive waste. Similar solubilities were obtained for thorium in all media, comprising NaOH, Ca(OH)2 and water equilibrated with a cement designed as repository backfill (NRVB, Nirex Reference Vault Backfill). In contrast, the solubility of U(VI) was one order of magnitude higher in NaOH than in the remaining solutions. The presence of cellulose degradation products (CDP) results in a comparable solubility increase for both elements...
March 26, 2017: Chemosphere
https://www.readbyqxmd.com/read/28361951/qualitative-and-quantitative-imaging-evaluation-of-renal-cell-carcinoma-subtypes-with-grating-based-x-ray-phase-contrast-ct
#11
Margarita Braunagel, Lorenz Birnbacher, Marian Willner, Mathias Marschner, Fabio De Marco, Manuel Viermetz, Susan Notohamiprodjo, Katharina Hellbach, Sigrid Auweter, Vera Link, Christine Woischke, Maximilian F Reiser, Franz Pfeiffer, Mike Notohamiprodjo, Julia Herzen
Current clinical imaging methods face limitations in the detection and correct characterization of different subtypes of renal cell carcinoma (RCC), while these are important for therapy and prognosis. The present study evaluates the potential of grating-based X-ray phase-contrast computed tomography (gbPC-CT) for visualization and characterization of human RCC subtypes. The imaging results for 23 ex vivo formalin-fixed human kidney specimens obtained with phase-contrast CT were compared to the results of the absorption-based CT (gbCT), clinical CT and a 3T MRI and validated using histology...
March 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28353340/cysteine-addition-promotes-sulfide-production-and-4-fold-hg-ii-s-coordination-in-actively-metabolizing-escherichia-coli
#12
Sara A Thomas, Jean-François Gaillard
The bacterial uptake of mercury(II), Hg(II), is believed to be energy-dependent and is enhanced by cysteine in diverse species of bacteria under aerobic and anaerobic conditions. To gain insight into this Hg(II) biouptake pathway, we have employed X-ray absorption spectroscopy (XAS) to investigate the relationship between exogenous cysteine, cellular metabolism, cellular localization, and Hg(II) coordination in aerobically respiring Escherichia coli (E. coli). We show that cells harvested in exponential growth phase consistently display mixtures of 2-fold and 4-fold Hg(II) coordination to sulfur (Hg-S2 and Hg-S4), with added cysteine enhancing Hg-S4 formation...
April 7, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28339107/studies-of-signal-estimation-bias-in-grating-based-x-ray-multi-contrast-imaging
#13
Xu Ji, Yongshuai Ge, Ran Zhang, Ke Li, Guang-Hong Chen
PURPOSE: In grating-based x-ray multi-contrast imaging, signals of three contrast mechanisms-absorption contrast, differential phase contrast (DPC), and dark-field contrast-can be estimated from the same set of acquired data. The estimated sig-nals, N0 (related to absorption), N1 (related to dark-field), and ϕ (related to DPC) may be intrinsically biased. However, it is yet unclear how large these biases are and how the data acquisition parameters affect the biases in the extracted signals...
March 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28338911/new-horizons-in-hospital-acquired-pneumonia-in-older-people
#14
Victoria Ewan, Thomas Hellyer, Julia Newton, John Simpson
Approximately 1.5% of hospital patients develop hospital acquired pneumonia. Aspiration is the major risk factor for pneumonia and is associated with reduced ability to mechanically clear respiratory pathogens into the stomach. Currently non-invasive methods of diagnosing hospital acquired pneumonia are less robust than invasive methods, and lead to over-diagnosis. Accurate diagnosis is key to surveillance, prevention and treatment of HAP, and also to improving outcomes; newer imaging modalities such as phase contrast X-ray imaging and nanoparticle enhanced magnetic resonance imaging may help...
February 27, 2017: Age and Ageing
https://www.readbyqxmd.com/read/28334658/extraction-of-the-3d-local-orientation-of-myocytes-in-human-cardiac-tissue-using-x-ray-phase-contrast-micro-tomography-and-multi-scale-analysis
#15
François Varray, Iulia Mirea, Max Langer, Françoise Peyrin, Laurent Fanton, Isabelle E Magnin
This paper presents a methodology to access the 3D local myocyte arrangements in fresh human post-mortem heart samples. We investigated the cardiac micro-structure at a high and isotropic resolution of 3.5 µm in three dimensions using X-ray phase micro-tomography at the European Synchrotron Radiation Facility. We then processed the reconstructed volumes to extract the 3D local orientation of the myocytes using a multi-scale approach with no segmentation. We created a simplified 3D model of tissue sample made of simulated myocytes with known size and orientations, to evaluate our orientation extraction method...
February 20, 2017: Medical Image Analysis
https://www.readbyqxmd.com/read/28329054/whole-heart-detailed-and-quantitative-anatomy-myofibre-structure-and-vasculature-from-x-ray-phase-contrast-synchrotron-radiation-based-micro-computed-tomography
#16
Anna Gonzalez-Tendero, Chong Zhang, Vedrana Balicevic, Rubén Cárdenes, Sven Loncaric, Constantine Butakoff, Bruno Paun, Anne Bonnin, Patricia Garcia-Cañadilla, Emma Muñoz-Moreno, Eduard Gratacós, Fatima Crispi, Bart Bijnens
Background: While individual cardiac myocytes only have a limited ability to shorten, the heart efficiently pumps a large volume-fraction thanks to a cell organization in a complex 3D fibre structure. Subclinical subtle cardiac structural remodelling is often present before symptoms arise. Understanding and early detection of these subtle changes is crucial for diagnosis and prevention. Additionally, personalized computational modelling requires knowledge on the multi-scale structure of the whole heart and vessels...
March 15, 2017: European Heart Journal Cardiovascular Imaging
https://www.readbyqxmd.com/read/28322316/grid-enhanced-x-ray-coded-aperture-microscopy-with-polycapillary-optics
#17
Katarzyna M Sowa, Arndt Last, Paweł Korecki
Polycapillary devices focus X-rays by means of multiple reflections of X-rays in arrays of bent glass capillaries. The size of the focal spot (typically 10-100 μm) limits the resolution of scanning, absorption and phase-contrast X-ray imaging using these devices. At the expense of a moderate resolution, polycapillary elements provide high intensity and are frequently used for X-ray micro-imaging with both synchrotrons and X-ray tubes. Recent studies have shown that the internal microstructure of such an optics can be used as a coded aperture that encodes high-resolution information about objects located inside the focal spot...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28319290/role-of-dissolved-and-molecular-oxygen-on-cu-and-ptcu-alloy-particle-structure-during-laser-ablation-synthesis-in-liquids
#18
Galina Marzun, Helmut Bönnemann, Christian Lehmann, Bernd Spliethoff, Claudia Weidenthaler, Stephan Barcikowski
The role of molecular oxygen dissolved in the solvent is often discussed as being an influential factor on particle oxidation during pulsed laser ablation in liquids. However, the formation of the particles during laser synthesis takes place under extreme conditions that enable the decomposition of the liquid medium. Reactive species of the solvent may then affect particle formation due to a chemical reaction in the reactive plasma. Experimental results show a difference between the role of dissolved molecular oxygen and the contribution from the oxygen in water molecules...
March 20, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28296356/positional-changes-of-the-ocular-organs-during-craniofacial-development
#19
Miho Osaka, Aoi Ishikawa, Shigehito Yamada, Chigako Uwabe, Hirohiko Imai, Tetsuya Matsuda, Akio Yoneyama, Tohoru Takeda, Tetsuya Takakuwa
The present study aimed to describe the positional changes of the ocular organs during craniofacial development; moreover, we examined the relationships among the ocular organs and other internal structures. To do this, we traced the positions of the ocular organs in 56 human early fetal samples at different stages of development using high-resolution magnetic resonance imaging and phase-contrast X-ray computed tomography. The eyes were located on the lateral side in the ventral view at Carnegie stage (CS) 16, and then changed their positions medially during development...
March 13, 2017: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
https://www.readbyqxmd.com/read/28287667/comparative-solution-equilibrium-studies-of-antitumor-ruthenium-%C3%AE-6-p-cymene-and-rhodium-%C3%AE-5-c5me5-complexes-of-8-hydroxyquinolines
#20
Orsolya Dömötör, Veronika F S Pape, Nóra V May, Gergely Szakács, Éva A Enyedy
Complex formation processes of [Ru(η(6)-p-cymene)(H2O)3](+) and [Rh(η(5)-C5Me5)(H2O)3](+) organometallic cations with 8-hydroxyquinoline (HQ) ligands were studied in aqueous solution by the combined use of (1)H NMR spectroscopy, UV-visible spectrophotometry and pH-potentiometry. Solution stability, chloride ion affinity and lipophilicity of the complexes were characterized together with the in vitro cytotoxicity against a pair of cancer cell lines, responsive and resistant to classic chemotherapy. The solid phase structure of the [Rh(η(5)-C5Me5)(8-quinolinolato)(Cl)] complex was characterized by single-crystal X-ray diffraction analysis...
March 27, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
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