WorldWideScience

Sample records for e4 electronic image

  1. Electron Paramagnetic Resonance Imaging

    Indian Academy of Sciences (India)

    Twentieth century bore witness to remarkable scientists whohave advanced our understanding of the brain. Among them,EPR (Electron Paramagnetic Resonance) imaging is particularlyuseful in monitoring hypoxic zones in tumors which arehighly resistant to radiation and chemotherapeutic treatment.This first part of the ...

  2. Electronic portal imaging devices

    International Nuclear Information System (INIS)

    Lief, Eugene

    2008-01-01

    The topics discussed include, among others, the following: Role of portal imaging; Port films vs. EPID; Image guidance: Elekta volume view; Delivery verification; Automation tasks of portal imaging; Types of portal imaging (Fluorescent screen, mirror, and CCD camera-based imaging; Liquid ion chamber imaging; Amorpho-silicon portal imagers; Fluoroscopic portal imaging; Kodak CR reader; and Other types of portal imaging devices); QA of EPID; and Portal dosimetry (P.A.)

  3. Electron Paramagnetic Resonance Imaging

    Indian Academy of Sciences (India)

    IAS Admin

    is Professor of Chemistry at. IIT Madras. ... speeding up the CW imaging by special novel methods. How- ever, the ... presence of gradients which are applied in two or three dimen- sions and ... optics and mechanical engineer- ing stands for ...

  4. Advances in imaging and electron physics

    CERN Document Server

    Hawkes, Peter W

    1995-01-01

    Academic Press is pleased to announce the creation of Advances in Imaging and Electron Physics. This serial publication results from the merger of two long running serials--Advances in Electronics and Electron Physics and Advances in Optical & Electron Microscopy. Advances in Imaging & Electron Physics will feature extended articles on the physics of electron devices (especially semiconductor devices), particle optics at high and low energies,microlithography, image science and digital image processing, electromagnetic wave propagation, electron microscopy, and the computing methods used in all these domains. Continuation order customers for either of the original Advances will receiveVolume 90, the first combined volume.

  5. Advances in imaging and electron physics

    CERN Document Server

    Mulvey, Tom

    1995-01-01

    Academic Press is pleased to announce the creation of Advances in Imaging and Electron Physics. This serial publication results from the merger of two long-running serials--Advances in Electronics and Electron Physics and Advances in Optical & Electron Microscopy. Advances in Imaging & Electron Physics will feature extended articles on the physics of electron devices (especially semiconductor devices), particle optics at high and low energies,microlithography, image science and digital image processing, electromagnetic wave propagation, electron microscopy, and the computing methods used in all these domains.

  6. Image formation and image analysis in electron microscopy

    International Nuclear Information System (INIS)

    Heel, M. van.

    1981-01-01

    This thesis covers various aspects of image formation and image analysis in electron microscopy. The imaging of relatively strong objects in partially coherent illumination, the coherence properties of thermionic emission sources and the detection of objects in quantum noise limited images are considered. IMAGIC, a fast, flexible and friendly image analysis software package is described. Intelligent averaging of molecular images is discussed. (C.F.)

  7. Transmission Electron Microscopy Physics of Image Formation

    CERN Document Server

    Kohl, Helmut

    2008-01-01

    Transmission Electron Microscopy: Physics of Image Formation presents the theory of image and contrast formation, and the analytical modes in transmission electron microscopy. The principles of particle and wave optics of electrons are described. Electron-specimen interactions are discussed for evaluating the theory of scattering and phase contrast. Also discussed are the kinematical and dynamical theories of electron diffraction and their applications for crystal-structure analysis and imaging of lattices and their defects. X-ray microanalysis and electron energy-loss spectroscopy are treated as analytical methods. Specimen damage and contamination by electron irradiation limits the resolution for biological and some inorganic specimens. This fifth edition includes discussion of recent progress, especially in the area of aberration correction and energy filtering; moreover, the topics introduced in the fourth edition have been updated. Transmission Electron Microscopy: Physics of Image Formation is written f...

  8. Electron cyclotron emission imaging in tokamak plasmas

    NARCIS (Netherlands)

    Munsat, T.; Domier, C.W.; Kong, X. Y.; Liang, T. R.; N C Luhmann Jr.,; Tobias, B. J.; Lee, W.; Park, H. K.; Yun, G.; Classen, I.G.J.; Donne, A. J. H.

    2010-01-01

    We discuss the recent history and latest developments of the electron cyclotron emission imaging diagnostic technique, wherein electron temperature is measured in magnetically confined plasmas with two-dimensional spatial resolution. The key enabling technologies for this technique are the

  9. Fundamentals of electronic image processing

    CERN Document Server

    Weeks, Arthur R

    1996-01-01

    This book is directed to practicing engineers and scientists who need to understand the fundamentals of image processing theory and algorithms to perform their technical tasks. It is intended to fill the gap between existing high-level texts dedicated to specialists in the field and the need for a more practical, fundamental text on image processing. A variety of example images are used to enhance reader understanding of how particular image processing algorithms work.

  10. Electron image reconstruction of helical protein assemblies

    International Nuclear Information System (INIS)

    Cremers, A.F.M.

    1980-01-01

    The analysis of projections of large ordered biological systems obtained by electron microscopy of negatively stained specimens is described. The biological structures amenable to this approach are constructed from a large number of identical protein molecules, which are arranged according to helical symmetry. Electron images of these structures generally contain sufficient information in order to calculate a three-dimensional density map. (Auth.)

  11. Cellular imaging electron tomography and related techniques

    CERN Document Server

    2018-01-01

    This book highlights important techniques for cellular imaging and covers the basics and applications of electron tomography and related techniques. In addition, it considers practical aspects and broadens the technological focus by incorporating techniques that are only now becoming accessible (e.g. block face imaging).  The first part of the book describes the electron microscopy 3D technique available to scientists around the world, allowing them to characterize organelles, cells and tissues. The major emphasis is on new technologies like scanning transmission electron microscopy (STEM) tomography, though the book also reviews some of the more proven technologies like electron tomography. In turn, the second part is dedicated to the reconstruction of data sets, signal improvement and interpretation.

  12. A reconfigurable image tube using an external electronic image readout

    Science.gov (United States)

    Lapington, J. S.; Howorth, J. R.; Milnes, J. S.

    2005-08-01

    We have designed and built a sealed tube microchannel plate (MCP) intensifier for optical/NUV photon counting applications suitable for 18, 25 and 40 mm diameter formats. The intensifier uses an electronic image readout to provide direct conversion of event position into electronic signals, without the drawbacks associated with phosphor screens and subsequent optical detection. The Image Charge technique is used to remove the readout from the intensifier vacuum enclosure, obviating the requirement for additional electrical vacuum feedthroughs and for the readout pattern to be UHV compatible. The charge signal from an MCP intensifier is capacitively coupled via a thin dielectric vacuum window to the electronic image readout, which is external to the sealed intensifier tube. The readout pattern is a separate item held in proximity to the dielectric window and can be easily detached, making the system easily reconfigurable. Since the readout pattern detects induced charge and is external to the tube, it can be constructed as a multilayer, eliminating the requirement for narrow insulator gaps and allowing it to be constructed using standard PCB manufacturing tolerances. We describe two readout patterns, the tetra wedge anode (TWA), an optimized 4 electrode device similar to the wedge and strip anode (WSA) but with a factor 2 improvement in resolution, and an 8 channel high speed 50 ohm device, both manufactured as multilayer PCBs. We present results of the detector imaging performance, image resolution, linearity and stability, and discuss the development of an integrated readout and electronics device based on these designs.

  13. Electron Holography Image Simulation of Nanoparticles

    NARCIS (Netherlands)

    Keimpema, K.; Raedt, H. De; Hosson, J.Th.M. De

    We discuss a real-space and a Fourier-space technique to compute numerically, the phase images observed by electron holography of nanoscale particles. An assessment of the applicability and accuracy of these techniques is made by calculating numerical results for simple geometries for which

  14. Velocity slice imaging for dissociative electron attachment

    Science.gov (United States)

    Nandi, Dhananjay; Prabhudesai, Vaibhav S.; Krishnakumar, E.; Chatterjee, A.

    2005-05-01

    A velocity slice imaging method is developed for measuring the angular distribution of fragment negative ions arising from dissociative electron attachment (DEA) to molecules. A low energy pulsed electron gun, a pulsed field ion extraction, and a two-dimensional position sensitive detector consisting of microchannel plates and a wedge-and-strip anode are used for this purpose. Detection and storage of each ion separately for its position and flight time allows analysis of the data offline for any given time slice, without resorting to pulsing the detector bias. The performance of the system is evaluated by measuring the angular distribution of O- from O2 and comparing it with existing data obtained using conventional technique. The capability of this technique in obtaining forward and backward angular distribution data is shown to have helped in resolving one of the existing problems in the electron scattering on O2.

  15. Incoherent imaging using dynamically scattered coherent electrons

    International Nuclear Information System (INIS)

    Nellist, P.D.; Pennycook, S.J.

    1999-01-01

    We use a Bloch wave approach to show that, even for coherent dynamical scattering from a stationary lattice with no absorption, annular dark-field imaging in a scanning transmission electron microscope gives a direct incoherent structure image of the atomic-column positions of a zone-axis-aligned crystal. Although many Bloch waves may be excited by the probe, the detector provides a filtering effect so that the 1s-type bound states are found to dominate the image contrast for typical experimental conditions. We also find that the column intensity is related to the transverse kinetic energy of the 1s states, which gives atomic number, Z, contrast. The additional effects of phonon scattering are discussed, in particular the reasons why phonon scattering is not a prerequisite for transverse incoherence. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  16. Quality assurance for electronic portal imaging devices

    International Nuclear Information System (INIS)

    Shalev, S.; Rajapakshe, R.; Gluhchev, G.; Luchka, K.

    1997-01-01

    Electronic portal imaging devices (EPIDS) are assuming an ever-increasing role in the verification of radiation treatment accuracy. They are used both in a passive capacity, for the determination of field displacement distributions (''setup errors''), and also in an active role whereby the patient setup is corrected on the basis of electronic portal images. In spite of their potential impact on the precision of patient treatment, there are few quality assurance procedures available, and most of the EPIDS in clinical use are subject, at best, to only perfunctory quality assurance. The goals of this work are (a) to develop an objective and reproducible test for EPID image quality on the factory floor and during installation of the EPID on site; (b) to provide the user with a simple and accurate tool for acceptance, commissioning, and routine quality control; and (c) to initiate regional, national and international collaboration in the implementation of standardized, objective, and automated quality assurance procedures. To this end we have developed an automated test in which a simple test object is imaged daily, and the spatial and contrast resolution of the EPID are automatically evaluated in terms of ''acceptable'', ''warning'' and ''stop'' criteria. Our experience over two years shows the test to be highly sensitive, reproducible, and inexpensive in time and effort. Inter-institutional trials are under way in Canada, US and Europe which indicate large variations in EPID image quality from one EPID to another, and from one center to another. We expect the new standardized quality assurance procedure to lead to improved, and consistent image quality, increased operator acceptance of the technology, and agreement on uniform standards by equipment suppliers and health care agencies. (author)

  17. The role of electronic media in shaping the country's image

    Directory of Open Access Journals (Sweden)

    Azel Zhanibek

    2011-07-01

    Full Text Available This article discusses the influence of electronic media in the country to external image of Kazakhstan. Special attention is paid to the experience of various countries in promoting the country's image by electronic media.

  18. Composition quantification of electron-transparent samples by backscattered electron imaging in scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Müller, E., E-mail: erich.mueller@kit.edu; Gerthsen, D.

    2017-02-15

    The contrast of backscattered electron (BSE) images in scanning electron microscopy (SEM) depends on material parameters which can be exploited for composition quantification if some information on the material system is available. As an example, the In-concentration in thin In{sub x}Ga{sub 1−x}As layers embedded in a GaAs matrix is analyzed in this work. The spatial resolution of the technique is improved by using thin electron-transparent specimens instead of bulk samples. Although the BSEs are detected in a comparably small angular range by an annular semiconductor detector, the image intensity can be evaluated to determine the composition and local thickness of the specimen. The measured intensities are calibrated within one single image to eliminate the influence of the detection and amplification system. Quantification is performed by comparison of experimental and calculated data. Instead of using time-consuming Monte-Carlo simulations, an analytical model is applied for BSE-intensity calculations which considers single electron scattering and electron diffusion. - Highlights: • Sample thickness and composition are quantified by backscattered electron imaging. • A thin sample is used to achieve spatial resolution of few nanometers. • Calculations are carried out with a time-saving electron diffusion model. • Small differences in atomic number and density detected at low electron energies.

  19. Advances in imaging and electron physics time resolved electron diffraction for chemistry, biology and material science

    CERN Document Server

    Hawkes, Peter W

    2014-01-01

    Advances in Imaging & Electron Physics merges two long-running serials-Advances in Electronics & Electron Physics and Advances in Optical & Electron Microscopy. The series features extended articles on the physics of electron devices (especially semiconductor devices), particle optics at high and low energies, microlithography, image science and digital image processing, electromagnetic wave propagation, electron microscopy, and the computing methods used in all these domains. Contributions from leading authorities Informs and updates on all the latest developments in the field.

  20. Secondary electron images obtained with a standard PEEM set up

    International Nuclear Information System (INIS)

    Benka, O.; Zeppenfeld, P.

    2004-01-01

    Secondary electron images excited by 3 to 4.3 keV electrons are obtained with a standard photoelectron electron emission microscope (PEEM) set up equipped with an imaging energy filter (IEF). The electron gun was mounted on a standard PEEM entrance flange at an angle of 25 o with respect to the sample surface. A low extraction voltage of 500 V was used to minimize the deflection of the electron beam by the PEEM extraction electrode. The secondary electron images are compared to photoelectron images excited by a standard 4.9 eV UV lamp. In the case of a Cu pattern on a Si substrate it is found that the lateral resolution without the IEF is about the same for electron and photon excitation but that the relative electron emission intensities are very different. The use of the IEF-reduces the lateral resolution. Images for secondary electron energies between eV 1 and eV 2 were obtained by setting the IEF to -V 1 and -V 2 ∼ -(V 1 + 5V) potentials and taking the difference of both images. Images up to 100 eV electron energies were recorded. The lateral resolution is in the range of μm. The material contrast obtained in these difference images are discussed in terms of a secondary electron and photoelectron emission model and secondary electron energy spectra measured with a LEED-Auger spectrometer. (author)

  1. Imaging Cytoskeleton Components by Electron Microscopy.

    Science.gov (United States)

    Svitkina, Tatyana

    2016-01-01

    The cytoskeleton is a complex of detergent-insoluble components of the cytoplasm playing critical roles in cell motility, shape generation, and mechanical properties of a cell. Fibrillar polymers-actin filaments, microtubules, and intermediate filaments-are major constituents of the cytoskeleton, which constantly change their organization during cellular activities. The actin cytoskeleton is especially polymorphic, as actin filaments can form multiple higher order assemblies performing different functions. Structural information about cytoskeleton organization is critical for understanding its functions and mechanisms underlying various forms of cellular activity. Because of the nanometer-scale thickness of cytoskeletal fibers, electron microscopy (EM) is a key tool to determine the structure of the cytoskeleton. This article describes application of rotary shadowing (or metal replica) EM for visualization of the cytoskeleton. The procedure is applicable to thin cultured cells growing on glass coverslips and consists of detergent extraction of cells to expose their cytoskeleton, chemical fixation to provide stability, ethanol dehydration and critical point drying to preserve three-dimensionality, rotary shadowing with platinum to create contrast, and carbon coating to stabilize replicas. This technique provides easily interpretable three-dimensional images, in which individual cytoskeletal fibers are clearly resolved, and individual proteins can be identified by immunogold labeling. More importantly, replica EM is easily compatible with live cell imaging, so that one can correlate the dynamics of a cell or its components, e.g., expressed fluorescent proteins, with high resolution structural organization of the cytoskeleton in the same cell.

  2. Transmission electron microscopy physics of image formation and microanalysis

    CERN Document Server

    Reimer, Ludwig

    1993-01-01

    "Transmission Electron Microscopy" presents the theory of image and contrastformation, and the analytical modes in transmission electron microscopy Theprinciples of particle and wave optics of electrons are described Electron-specimen interactions are discussed for evaluating the theory of scattering and phase contrast Also analysed are the kinetical and dynamical theories of electron diffraction and their applications for crystal-structure determination and imaging of lattices and their defects X-ray microanalysis and electron energy-loss spectroscopy are treated as analytical methods The third edition includes a brief discussionof Schottky emission guns, some clarification of minor details, and references to the recent literature

  3. Characteristics of different frequency ranges in scanning electron microscope images

    International Nuclear Information System (INIS)

    Sim, K. S.; Nia, M. E.; Tan, T. L.; Tso, C. P.; Ee, C. S.

    2015-01-01

    We demonstrate a new approach to characterize the frequency range in general scanning electron microscope (SEM) images. First, pure frequency images are generated from low frequency to high frequency, and then, the magnification of each type of frequency image is implemented. By comparing the edge percentage of the SEM image to the self-generated frequency images, we can define the frequency ranges of the SEM images. Characterization of frequency ranges of SEM images benefits further processing and analysis of those SEM images, such as in noise filtering and contrast enhancement

  4. Characteristics of different frequency ranges in scanning electron microscope images

    Energy Technology Data Exchange (ETDEWEB)

    Sim, K. S., E-mail: kssim@mmu.edu.my; Nia, M. E.; Tan, T. L.; Tso, C. P.; Ee, C. S. [Faculty of Engineering and Technology, Multimedia University, 75450 Melaka (Malaysia)

    2015-07-22

    We demonstrate a new approach to characterize the frequency range in general scanning electron microscope (SEM) images. First, pure frequency images are generated from low frequency to high frequency, and then, the magnification of each type of frequency image is implemented. By comparing the edge percentage of the SEM image to the self-generated frequency images, we can define the frequency ranges of the SEM images. Characterization of frequency ranges of SEM images benefits further processing and analysis of those SEM images, such as in noise filtering and contrast enhancement.

  5. Electronic structure classifications using scanning tunneling microscopy conductance imaging

    International Nuclear Information System (INIS)

    Horn, K.M.; Swartzentruber, B.S.; Osbourn, G.C.; Bouchard, A.; Bartholomew, J.W.

    1998-01-01

    The electronic structure of atomic surfaces is imaged by applying multivariate image classification techniques to multibias conductance data measured using scanning tunneling microscopy. Image pixels are grouped into classes according to shared conductance characteristics. The image pixels, when color coded by class, produce an image that chemically distinguishes surface electronic features over the entire area of a multibias conductance image. Such open-quotes classedclose quotes images reveal surface features not always evident in a topograph. This article describes the experimental technique used to record multibias conductance images, how image pixels are grouped in a mathematical, classification space, how a computed grouping algorithm can be employed to group pixels with similar conductance characteristics in any number of dimensions, and finally how the quality of the resulting classed images can be evaluated using a computed, combinatorial analysis of the full dimensional space in which the classification is performed. copyright 1998 American Institute of Physics

  6. 2-D Imaging of Electron Temperature in Tokamak Plasmas

    International Nuclear Information System (INIS)

    Munsat, T.; Mazzucato, E.; Park, H.; Domier, C.W.; Johnson, M.; Luhmann, N.C. Jr.; Wang, J.; Xia, Z.; Classen, I.G.J.; Donne, A.J.H.; Pol, M.J. van de

    2004-01-01

    By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented

  7. Transmission electron microscopy physics of image formation and microanalysis

    CERN Document Server

    Reimer, Ludwig

    1997-01-01

    Transmission Electron Microscopy presents the theory of image and contrast formation, and the analytical modes in transmission electron microscopy. The principles of particle and wave optics of electrons are described. Electron-specimen interactions are discussed for evaluating the theory of scattering and phase contrast. Also discussed are the kinematical and dynamical theories of electron diffraction and their applications for crystal-structure analysis and imaging of lattices and their defects. X-ray micronanalysis and electron energy-loss spectroscopy are treated as analytical methods. Specimen damage and contamination by electron irradiation limits the resolution for biological and some inorganic specimens. This fourth edition includes discussion of recent progress, especially in the area of Schottky emission guns, convergent-beam electron diffraction, electron tomography, holography and the high resolution of crystal lattices.

  8. Imaging differential polarization microscope with electronic readout

    International Nuclear Information System (INIS)

    Mickols, W.; Tinoco, I.; Katz, J.E.; Maestre, M.F.; Bustamante, C.

    1985-01-01

    A differential polarization microscope forms two images: one of the transmitted intensity and the other due to the change in intensity between images formed when different polarizations of light are used. The interpretation of these images for linear dichroism and circular dichroism are described. The design constraints on the data acquisition systems and the polarization modulation are described. The advantage of imaging several biological systems which contain optically anisotropic structures are described

  9. Angularly-selective transmission imaging in a scanning electron microscope.

    Science.gov (United States)

    Holm, Jason; Keller, Robert R

    2016-08-01

    This work presents recent advances in transmission scanning electron microscopy (t-SEM) imaging control capabilities. A modular aperture system and a cantilever-style sample holder that enable comprehensive angular selectivity of forward-scattered electrons are described. When combined with a commercially available solid-state transmission detector having only basic bright-field and dark-field imaging capabilities, the advances described here enable numerous transmission imaging modes. Several examples are provided that demonstrate how contrast arising from diffraction to mass-thickness can be obtained. Unanticipated image contrast at some imaging conditions is also observed and addressed. Published by Elsevier B.V.

  10. Imaging electron flow from collimating contacts in graphene

    Science.gov (United States)

    Bhandari, S.; Lee, G. H.; Watanabe, K.; Taniguchi, T.; Kim, P.; Westervelt, R. M.

    2018-04-01

    The ballistic motion of electrons in graphene opens exciting opportunities for electron-optic devices based on collimated electron beams. We form a collimating contact in a hBN-encapsulated graphene hall bar by adding zigzag contacts on either side of an electron emitter that absorb stray electrons; collimation can be turned off by floating the zig-zag contacts. The electron beam is imaged using a liquid-He cooled scanning gate microscope (SGM). The tip deflects electrons as they pass from the collimating contact to a receiving contact on the opposite side of the channel, and an image of electron flow can be made by displaying the change in transmission as the tip is raster scanned across the sample. The angular half width Δθ of the electron beam is found by applying a perpendicular magnetic field B that bends electron paths into cyclotron orbits. The images reveal that the electron flow from the collimating contact drops quickly at B  =  0.05 T when the electron orbits miss the receiving contact. The flow for the non-collimating case persists longer, up to B  =  0.19 T, due to the broader range of entry angles. Ray-tracing simulations agree well with the experimental images. By fitting the fields B at which the magnitude of electron flow drops in the experimental SGM images, we find Δθ  =  9° for electron flow from the collimating contact, compared with Δθ  =  54° for the non-collimating case.

  11. High energy electron multibeam diffraction and imaging

    International Nuclear Information System (INIS)

    Bourret, Alain.

    1980-04-01

    The different theories of dynamical scattering of electrons are firstly reviewed with special reference to their basis and the validity of the different approximations. Then after a short description of the different experimental set ups, structural analysis and the investigation of the optical potential by means of high energy electrons will be surveyed

  12. Foucault imaging by using non-dedicated transmission electron microscope

    International Nuclear Information System (INIS)

    Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

    2012-01-01

    An electron optical system for observing Foucault images was constructed using a conventional transmission electron microscope without any special equipment for Lorentz microscopy. The objective lens was switched off and an electron beam was converged by a condenser optical system to the crossover on the selected area aperture plane. The selected area aperture was used as an objective aperture to select the deflected beam for Foucault mode, and the successive image-forming lenses were controlled for observation of the specimen images. The irradiation area on the specimen was controlled by selecting the appropriate diameter of the condenser aperture.

  13. Foucault imaging by using non-dedicated transmission electron microscope

    Science.gov (United States)

    Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

    2012-08-01

    An electron optical system for observing Foucault images was constructed using a conventional transmission electron microscope without any special equipment for Lorentz microscopy. The objective lens was switched off and an electron beam was converged by a condenser optical system to the crossover on the selected area aperture plane. The selected area aperture was used as an objective aperture to select the deflected beam for Foucault mode, and the successive image-forming lenses were controlled for observation of the specimen images. The irradiation area on the specimen was controlled by selecting the appropriate diameter of the condenser aperture.

  14. Foucault imaging by using non-dedicated transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Taniguchi, Yoshifumi [Science and Medical Systems Business Group, Hitachi High-Technologies Corp., Ichige, Hitachinaka, Ibaraki 312-8504 (Japan); Matsumoto, Hiroaki [Corporate Manufacturing Strategy Group, Hitachi High-Technologies Corp., Ishikawa-cho, Hitachinaka, Ibaraki 312-1991 (Japan); Harada, Ken [Central Research Laboratory, Hitachi Ltd., Hatoyama, Saitama 350-0395 (Japan)

    2012-08-27

    An electron optical system for observing Foucault images was constructed using a conventional transmission electron microscope without any special equipment for Lorentz microscopy. The objective lens was switched off and an electron beam was converged by a condenser optical system to the crossover on the selected area aperture plane. The selected area aperture was used as an objective aperture to select the deflected beam for Foucault mode, and the successive image-forming lenses were controlled for observation of the specimen images. The irradiation area on the specimen was controlled by selecting the appropriate diameter of the condenser aperture.

  15. Simulation study of secondary electron images in scanning ion microscopy

    CERN Document Server

    Ohya, K

    2003-01-01

    The target atomic number, Z sub 2 , dependence of secondary electron yield is simulated by applying a Monte Carlo code for 17 species of metals bombarded by Ga ions and electrons in order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM). In addition to the remarkable reversal of the Z sub 2 dependence between the Ga ion and electron bombardment, a fine structure, which is correlated to the density of the conduction band electrons in the metal, is calculated for both. The brightness changes of the secondary electron images in SIM and SEM are simulated using Au and Al surfaces adjacent to each other. The results indicate that the image contrast in SIM is much more sensitive to the material species and is clearer than that for SEM. The origin of the difference between SIM and SEM comes from the difference in the lateral distribution of secondary electrons excited within the escape depth.

  16. Advances in imaging and electron physics the scanning transmission electron microscope

    CERN Document Server

    Hawkes, Peter W

    2009-01-01

    Advances in Imaging and Electron Physics merges two long-running serials--Advances in Electronics and Electron Physics and Advances in Optical and Electron Microscopy. This series features extended articles on the physics of electron devices (especially semiconductor devices), particle optics at high and low energies, microlithography, image science and digital image processing, electromagnetic wave propagation, electron microscopy, and the computing methods used in all these domains.  This particular volume presents several timely articles on the scanning transmission electron microscope. Updated with contributions from leading international scholars and industry experts Discusses hot topic areas and presents current and future research trends Provides an invaluable reference and guide for physicists, engineers and mathematicians.

  17. Imaging of osteo-odonto-keratoprosthesis by electron beam tomography

    OpenAIRE

    Fong, K C S; Ferrett, C G; Tandon, R; Paul, B; Herold, J; Liu, C S C

    2005-01-01

    Aim: To describe the experience of using electron beam tomography (EBT) in imaging of osteo-odonto-keratoprosthesis (OOKP) to identify early bone and dentine loss which may threaten the viability of the eye.

  18. Electronic imaging applied to neutron radiography

    International Nuclear Information System (INIS)

    Garrett, D.A.; Bracher, D.A.

    1976-01-01

    A commercially - available image intensifier was used with a scan conversion memory and a mobile 252 Cf based neutron radiography system to obtain neutron radiographs on a television monitor in 0.5 minutes to 10.0 minutes

  19. Electronic viewbox: An integrated image diagnostic working station

    International Nuclear Information System (INIS)

    Minato, K.; Komori, M.; Hirakawa, A.; Kuwahara, M.; Yonekura, Y.; Torizuka, K.; Brill, A.B.

    1985-01-01

    Recent development in medical imaging technology have been introducing variety of digital images in clinical medicine, and handling these multi-modality digital images in one place is needed for efficient clinical diagnosis. The authors proposed a concept of an integrated image diagnostic working station, in which a physician can look into all clinical images, can select any key image for diagnosis and can read it in detail. A prototype working station named ''Electronic Viewbox'' has been developed for this purpose. It has three distinctive features. 1. The stored images of a patient are shown at a glance. In order to achieve this function, each original image is attached to a small image, where the data are compressed to reserve the essence of the image, and many of these small images are displayed on a CRT screen. This small image is used as an index for picking up a key image in the archived clinical images. 2. The working station is compact enough to be set on a desk. Only two CRTs and a pointing device are assembled. These two CRT screens are used mutually for retrieving key images and for displaying the original images. 3. All operations can be done interactively using cursor and icons

  20. Imaging electron wave functions inside open quantum rings.

    Science.gov (United States)

    Martins, F; Hackens, B; Pala, M G; Ouisse, T; Sellier, H; Wallart, X; Bollaert, S; Cappy, A; Chevrier, J; Bayot, V; Huant, S

    2007-09-28

    Combining scanning gate microscopy (SGM) experiments and simulations, we demonstrate low temperature imaging of the electron probability density |Psi|(2)(x,y) in embedded mesoscopic quantum rings. The tip-induced conductance modulations share the same temperature dependence as the Aharonov-Bohm effect, indicating that they originate from electron wave function interferences. Simulations of both |Psi|(2)(x,y) and SGM conductance maps reproduce the main experimental observations and link fringes in SGM images to |Psi|(2)(x,y).

  1. A new clustering algorithm for scanning electron microscope images

    Science.gov (United States)

    Yousef, Amr; Duraisamy, Prakash; Karim, Mohammad

    2016-04-01

    A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with the sample atoms, producing various signals that are collected by detectors. The gathered signals contain information about the sample's surface topography and composition. The electron beam is generally scanned in a raster scan pattern, and the beam's position is combined with the detected signal to produce an image. The most common configuration for an SEM produces a single value per pixel, with the results usually rendered as grayscale images. The captured images may be produced with insufficient brightness, anomalous contrast, jagged edges, and poor quality due to low signal-to-noise ratio, grained topography and poor surface details. The segmentation of the SEM images is a tackling problems in the presence of the previously mentioned distortions. In this paper, we are stressing on the clustering of these type of images. In that sense, we evaluate the performance of the well-known unsupervised clustering and classification techniques such as connectivity based clustering (hierarchical clustering), centroid-based clustering, distribution-based clustering and density-based clustering. Furthermore, we propose a new spatial fuzzy clustering technique that works efficiently on this type of images and compare its results against these regular techniques in terms of clustering validation metrics.

  2. On the Progress of Scanning Transmission Electron Microscopy (STEM) Imaging in a Scanning Electron Microscope.

    Science.gov (United States)

    Sun, Cheng; Müller, Erich; Meffert, Matthias; Gerthsen, Dagmar

    2018-04-01

    Transmission electron microscopy (TEM) with low-energy electrons has been recognized as an important addition to the family of electron microscopies as it may avoid knock-on damage and increase the contrast of weakly scattering objects. Scanning electron microscopes (SEMs) are well suited for low-energy electron microscopy with maximum electron energies of 30 keV, but they are mainly used for topography imaging of bulk samples. Implementation of a scanning transmission electron microscopy (STEM) detector and a charge-coupled-device camera for the acquisition of on-axis transmission electron diffraction (TED) patterns, in combination with recent resolution improvements, make SEMs highly interesting for structure analysis of some electron-transparent specimens which are traditionally investigated by TEM. A new aspect is correlative SEM, STEM, and TED imaging from the same specimen region in a SEM which leads to a wealth of information. Simultaneous image acquisition gives information on surface topography, inner structure including crystal defects and qualitative material contrast. Lattice-fringe resolution is obtained in bright-field STEM imaging. The benefits of correlative SEM/STEM/TED imaging in a SEM are exemplified by structure analyses from representative sample classes such as nanoparticulates and bulk materials.

  3. A literature review of electronic portal imaging for radiotherapy dosimetry

    NARCIS (Netherlands)

    van Elmpt, Wouter; McDermott, Leah; Nijsten, Sebastiaan; Wendling, Markus; Lambin, Philippe; Mijnheer, Ben

    2008-01-01

    Electronic portal imaging devices (EPIDs) have been the preferred tools for verification of patient positioning for radiotherapy in recent decades. Since EPID images contain dose information, many groups have investigated their use for radiotherapy dose measurement. With the introduction of the

  4. Electron accelerating unit for streak image tubes

    Indian Academy of Sciences (India)

    The simulation results show that the accelerating unit improves both the spatial and temporal .... This electron emission process is simulated as a statistical sample in terms of Monte ... solver using above method in MATLAB language. First the .... semiconductors and insulators: Models and measurements. J. Phys. Rev.

  5. CMOS Image Sensors: Electronic Camera On A Chip

    Science.gov (United States)

    Fossum, E. R.

    1995-01-01

    Recent advancements in CMOS image sensor technology are reviewed, including both passive pixel sensors and active pixel sensors. On- chip analog to digital converters and on-chip timing and control circuits permit realization of an electronic camera-on-a-chip. Highly miniaturized imaging systems based on CMOS image sensor technology are emerging as a competitor to charge-coupled devices for low cost uses.

  6. Scanning transmission electron microscopy imaging and analysis

    CERN Document Server

    Pennycook, Stephen J

    2011-01-01

    Provides the first comprehensive treatment of the physics and applications of this mainstream technique for imaging and analysis at the atomic level Presents applications of STEM in condensed matter physics, materials science, catalysis, and nanoscience Suitable for graduate students learning microscopy, researchers wishing to utilize STEM, as well as for specialists in other areas of microscopy Edited and written by leading researchers and practitioners

  7. [Electronic Device for Retinal and Iris Imaging].

    Science.gov (United States)

    Drahanský, M; Kolář, R; Mňuk, T

    This paper describes design and construction of a new device for automatic capturing of eye retina and iris. This device has two possible ways of utilization - either for biometric purposes (persons recognition on the base of their eye characteristics) or for medical purposes as supporting diagnostic device. eye retina, eye iris, device, acquisition, image.

  8. Imaging the motion of electrons across semiconductor heterojunctions

    Science.gov (United States)

    Man, Michael K. L.; Margiolakis, Athanasios; Deckoff-Jones, Skylar; Harada, Takaaki; Wong, E. Laine; Krishna, M. Bala Murali; Madéo, Julien; Winchester, Andrew; Lei, Sidong; Vajtai, Robert; Ajayan, Pulickel M.; Dani, Keshav M.

    2017-01-01

    Technological progress since the late twentieth century has centred on semiconductor devices, such as transistors, diodes and solar cells. At the heart of these devices is the internal motion of electrons through semiconductor materials due to applied electric fields or by the excitation of photocarriers. Imaging the motion of these electrons would provide unprecedented insight into this important phenomenon, but requires high spatial and temporal resolution. Current studies of electron dynamics in semiconductors are generally limited by the spatial resolution of optical probes, or by the temporal resolution of electronic probes. Here, by combining femtosecond pump-probe techniques with spectroscopic photoemission electron microscopy, we imaged the motion of photoexcited electrons from high-energy to low-energy states in a type-II 2D InSe/GaAs heterostructure. At the instant of photoexcitation, energy-resolved photoelectron images revealed a highly non-equilibrium distribution of photocarriers in space and energy. Thereafter, in response to the out-of-equilibrium photocarriers, we observed the spatial redistribution of charges, thus forming internal electric fields, bending the semiconductor bands, and finally impeding further charge transfer. By assembling images taken at different time-delays, we produced a movie lasting a few trillionths of a second of the electron-transfer process in the photoexcited type-II heterostructure—a fundamental phenomenon in semiconductor devices such as solar cells. Quantitative analysis and theoretical modelling of spatial variations in the movie provide insight into future solar cells, 2D materials and other semiconductor devices.

  9. Platinum replica electron microscopy: Imaging the cytoskeleton globally and locally.

    Science.gov (United States)

    Svitkina, Tatyana M

    2017-05-01

    Structural studies reveal how smaller components of a system work together as a whole. However, combining high resolution of details with full coverage of the whole is challenging. In cell biology, light microscopy can image many cells in their entirety, but at a lower resolution, whereas electron microscopy affords very high resolution, but usually at the expense of the sample size and coverage. Structural analyses of the cytoskeleton are especially demanding, because cytoskeletal networks are unresolvable by light microscopy due to their density and intricacy, whereas their proper preservation is a challenge for electron microscopy. Platinum replica electron microscopy can uniquely bridge the gap between the "comfort zones" of light and electron microscopy by allowing high resolution imaging of the cytoskeleton throughout the entire cell and in many cells in the population. This review describes the principles and applications of platinum replica electron microscopy for studies of the cytoskeleton. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Scanning electron microscopy physics of image formation and microanalysis

    CERN Document Server

    Reimer, Ludwig

    1985-01-01

    The aim of this book is to outline the physics of image formation, electron­ specimen interactions, imaging modes, the interpretation of micrographs and the use of quantitative modes "in scanning electron microscopy (SEM). lt forms a counterpart to Transmission Electron Microscopy (Vol. 36 of this Springer Series in Optical Sciences) . The book evolved from lectures delivered at the University of Münster and from a German text entitled Raster-Elektronenmikroskopie (Springer-Verlag), published in collaboration with my colleague Gerhard Pfefferkorn. In the introductory chapter, the principles of the SEM and of electron­ specimen interactions are described, the most important imaging modes and their associated contrast are summarized, and general aspects of eiemental analysis by x-ray and Auger electron emission are discussed. The electron gun and electron optics are discussed in Chap. 2 in order to show how an electron probe of small diameter can be formed, how the elec­ tron beam can be blanked at high fre...

  11. Image timing and detector performance of a matrix ion-chamber electronic portal imaging device

    International Nuclear Information System (INIS)

    Greer, P.

    1996-01-01

    The Oncology Centre of Auckland Hospital recently purchased a Varian PortalVision TM electronic portal imaging device (EPID). Image acquisition times, input-output characteristics and contrast-detail curves of this matrix liquid ion-chamber EPID have been measured to examine the variation in imaging performance with acquisition mode. The variation in detector performance with acquisition mode has been examined. The HV cycle time can be increased to improve image quality. Consideration should be given to the acquisition mode and HV cycle time used when imaging to ensure adequate imaging performance with reasonable imaging time. (author)

  12. Image processing of small protein-crystals in electron microscopy

    International Nuclear Information System (INIS)

    Feinberg, D.A.

    1978-11-01

    This electron microscope study was undertaken to determine whether high resolution reconstructed images could be obtained from statistically noisy micrographs by the super-position of several small areas of images of well-ordered crystals of biological macromolecules. Methods of rotational and translational alignment which use Fourier space data were demonstrated to be superior to methods which use Real space image data. After alignment, the addition of the diffraction patterns of four small areas did not produce higher resolution because of unexpected image distortion effects. A method was developed to determine the location of the distortion origin and the coefficients of spiral distortion and pincushion/barrel distortion in order to make future correction of distortions in electron microscope images of large area crystals

  13. Algorithms for contrast enhancement of electronic portal images

    International Nuclear Information System (INIS)

    Díez, S.; Sánchez, S.

    2015-01-01

    An implementation of two new automatized image processing algorithms for contrast enhancement of portal images is presented as suitable tools which facilitate the setup verification and visualization of patients during radiotherapy treatments. In the first algorithm, called Automatic Segmentation and Histogram Stretching (ASHS), the portal image is automatically segmented in two sub-images delimited by the conformed treatment beam: one image consisting of the imaged patient obtained directly from the radiation treatment field, and the second one is composed of the imaged patient outside it. By segmenting the original image, a histogram stretching can be independently performed and improved in both regions. The second algorithm involves a two-step process. In the first step, a Normalization to Local Mean (NLM), an inverse restoration filter is applied by dividing pixel by pixel a portal image by its blurred version. In the second step, named Lineally Combined Local Histogram Equalization (LCLHE), the contrast of the original image is strongly improved by a Local Contrast Enhancement (LCE) algorithm, revealing the anatomical structures of patients. The output image is lineally combined with a portal image of the patient. Finally the output images of the previous algorithms (NLM and LCLHE) are lineally combined, once again, in order to obtain a contrast enhanced image. These two algorithms have been tested on several portal images with great results. - Highlights: • Two Algorithms are implemented to improve the contrast of Electronic Portal Images. • The multi-leaf and conformed beam are automatically segmented into Portal Images. • Hidden anatomical and bony structures in portal images are revealed. • The task related to the patient setup verification is facilitated by the contrast enhancement then achieved.

  14. Future directions in electronic image handling.

    Science.gov (United States)

    Lemke, H U

    1993-08-01

    After a relatively slow start compared with the United States and Japan, several projects are now being established in Europe that are aimed at the development of prototype systems for medical image processing and management. Frequently, this includes aspects of multimedia communication, as well as legal, ethical, and economic issues. Consideration is also often given to systems security, reliability, and data protection. All these projects are based on the application of modern computer and communication technologies. The following interesting conclusions can be drawn from these preliminary activities: 1. PACS and IMAC systems should not be regarded as products or devices, but as a means to improve the infrastructure in a given medical care environment. Sometimes this activity is also referred to as knowledge business. Individual components of these systems, for example image acquisition devices, networks, storage facilities, and medical workstations, should be provided with standard interfaces allowing a modular build-up and an easy adaptation to the specific conditions of clinical departments. 2. Digital luminescence radiography will further establish itself as a method for image acquisition and increasingly will replace analog radiologic methods. Consequently, digital processing, archiving, and communication will be a necessity for optimal patient care. 3. New network technologies and magnetic-optical storage media offer the possibility of an improved cost-effectiveness for communication and storage. They should therefore be considered an important factor in future economic considerations regarding health care services. 4. The practice of modern medicine is based on team-work; good communication among the parties concerned is a critical factor.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. E-4 Test Facility Design Status

    Science.gov (United States)

    Ryan, Harry; Canady, Randy; Sewell, Dale; Rahman, Shamim; Gilbrech, Rick

    2001-01-01

    Combined-cycle propulsion technology is a strong candidate for meeting NASA space transportation goals. Extensive ground testing of integrated air-breathing/rocket system (e.g., components, subsystems and engine systems) across all propulsion operational modes (e.g., ramjet, scramjet) will be needed to demonstrate this propulsion technology. Ground testing will occur at various test centers based on each center's expertise. Testing at the NASA John C. Stennis Space Center will be primarily concentrated on combined-cycle power pack and engine systems at sea level conditions at a dedicated test facility, E-4. This paper highlights the status of the SSC E-4 test Facility design.

  16. Survey of standards for electronic image displays

    Science.gov (United States)

    Rowe, William A.

    1996-02-01

    Electronic visual displays have been evolving from the 1960's basis of cathode ray tube (CRT) technology. Now, many other technologies are also available, including both flat panels and projection displays. Standards for these displays are being developed at both the national level and the international levels. Standards activity within the United States is in its infancy and is fragmented according to the inclination of each of the standards developing organizations. The latest round of flat panel display technology was primarily developed in Japan. Initially standards arose from component vendor-to-OEM customer relationships. As a result, Japanese standards for components are the best developed. The Electronics Industries Association of Japan (EIAJ) is providing their standards to the International Electrotechnical Commission (IEC) for adoption. On the international level, professional societies such as the human factors society (hfs) and the International Organization for Standardization (ISO) have completed major standards, hfs developed the first ergonomic standard hfs-100 and the ISO has developed some sections of a broader ergonomic standard ISO 9241. This paper addresses the organization of standards activity. Active organizations and their areas of focus are identified. The major standards that have been completed or are in development are described. Finally, suggestions for improving the this standards activity are proposed.

  17. Droplet Epitaxy Image Contrast in Mirror Electron Microscopy

    Science.gov (United States)

    Kennedy, S. M.; Zheng, C. X.; Jesson, D. E.

    2017-01-01

    Image simulation methods are applied to interpret mirror electron microscopy (MEM) images obtained from a movie of GaAs droplet epitaxy. Cylindrical symmetry of structures grown by droplet epitaxy is assumed in the simulations which reproduce the main features of the experimental MEM image contrast, demonstrating that droplet epitaxy can be studied in real-time. It is therefore confirmed that an inner ring forms at the droplet contact line and an outer ring (or skirt) occurs outside the droplet periphery. We believe that MEM combined with image simulations will be increasingly used to study the formation and growth of quantum structures.

  18. Quantitative methods for the analysis of electron microscope images

    DEFF Research Database (Denmark)

    Skands, Peter Ulrik Vallø

    1996-01-01

    The topic of this thesis is an general introduction to quantitative methods for the analysis of digital microscope images. The images presented are primarily been acquired from Scanning Electron Microscopes (SEM) and interfermeter microscopes (IFM). The topic is approached though several examples...... foundation of the thesis fall in the areas of: 1) Mathematical Morphology; 2) Distance transforms and applications; and 3) Fractal geometry. Image analysis opens in general the possibility of a quantitative and statistical well founded measurement of digital microscope images. Herein lies also the conditions...

  19. Markov random field based automatic image alignment for electron tomography.

    Science.gov (United States)

    Amat, Fernando; Moussavi, Farshid; Comolli, Luis R; Elidan, Gal; Downing, Kenneth H; Horowitz, Mark

    2008-03-01

    We present a method for automatic full-precision alignment of the images in a tomographic tilt series. Full-precision automatic alignment of cryo electron microscopy images has remained a difficult challenge to date, due to the limited electron dose and low image contrast. These facts lead to poor signal to noise ratio (SNR) in the images, which causes automatic feature trackers to generate errors, even with high contrast gold particles as fiducial features. To enable fully automatic alignment for full-precision reconstructions, we frame the problem probabilistically as finding the most likely particle tracks given a set of noisy images, using contextual information to make the solution more robust to the noise in each image. To solve this maximum likelihood problem, we use Markov Random Fields (MRF) to establish the correspondence of features in alignment and robust optimization for projection model estimation. The resulting algorithm, called Robust Alignment and Projection Estimation for Tomographic Reconstruction, or RAPTOR, has not needed any manual intervention for the difficult datasets we have tried, and has provided sub-pixel alignment that is as good as the manual approach by an expert user. We are able to automatically map complete and partial marker trajectories and thus obtain highly accurate image alignment. Our method has been applied to challenging cryo electron tomographic datasets with low SNR from intact bacterial cells, as well as several plastic section and X-ray datasets.

  20. Imaging hydrated microbial extracellular polymers: Comparative analysis by electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dohnalkova, A.C.; Marshall, M. J.; Arey, B. W.; Williams, K. H.; Buck, E. C.; Fredrickson, J. K.

    2011-01-01

    Microbe-mineral and -metal interactions represent a major intersection between the biosphere and geosphere but require high-resolution imaging and analytical tools for investigating microscale associations. Electron microscopy has been used extensively for geomicrobial investigations and although used bona fide, the traditional methods of sample preparation do not preserve the native morphology of microbiological components, especially extracellular polymers. Herein, we present a direct comparative analysis of microbial interactions using conventional electron microscopy approaches of imaging at room temperature and a suite of cryogenic electron microscopy methods providing imaging in the close-to-natural hydrated state. In situ, we observed an irreversible transformation of the hydrated bacterial extracellular polymers during the traditional dehydration-based sample preparation that resulted in their collapse into filamentous structures. Dehydration-induced polymer collapse can lead to inaccurate spatial relationships and hence could subsequently affect conclusions regarding nature of interactions between microbial extracellular polymers and their environment.

  1. Importance of daily electronic portal imaging in radiotherapy

    International Nuclear Information System (INIS)

    Bell, L. J.; Shakespeare, T. P.; Willis, A.

    2008-01-01

    Full text: An audit was conducted on 20 randomly selected patients who had daily electronic portal imaging during the course of their radiotherapy treatment. The daily images were reviewed to determine whether they were within tolerance according to departmental protocol. If they were not, the actions that were taken were documented. Four treatment areas (spine, chest, breast and prostate) were compared among five patients belonging to each of these categories. The patients were also categorized according to their treatment intent (radical or palliative). A total of 889 electronic portal images of 475 fractions were audited and 33.5% of all fractions were outside tolerance. It was found that 95% of patients needed an action during their treatment and 80% of the patients needed a treatment centre move during the course of their treatment. We found that errors occurred throughout the treatment and it was not possible to predict patients who could have daily imaging omitted. Concordance between radiation therapists and radiation oncologists for identification of error was also investigated. Despite the use of familiar electronic portal imaging protocols, image reviewers (radiation therapists and radiation oncologists) disagreed in interpretation 10% of the time. Our results support the hypothesis that daily imaging may be a useful tool for patients undergoing radiotherapy and that imaging may be ideally carried out before each fraction. Image assessments would be ideally carried out by a team approach, with all images reviewed by both radiation therapists and radiation oncologists. This approach has significant resource implications and may require review of current Medicare and Health Program Grant reimbursements.

  2. Transmission electron microscopy physics of image formation and microanalysis

    CERN Document Server

    Reimer, Ludwig

    1984-01-01

    The aim of this book is to outline the physics of image formation, electron­ specimen interactions and image interpretation in transmission electron mic­ roscopy. The book evolved from lectures delivered at the University of Munster and is a revised version of the first part of my earlier book Elek­ tronenmikroskopische Untersuchungs- und Priiparationsmethoden, omitting the part which describes specimen-preparation methods. In the introductory chapter, the different types of electron microscope are compared, the various electron-specimen interactions and their applications are summarized and the most important aspects of high-resolution, analytical and high-voltage electron microscopy are discussed. The optics of electron lenses is discussed in Chapter 2 in order to bring out electron-lens properties that are important for an understanding of the function of an electron microscope. In Chapter 3, the wave optics of elec­ trons and the phase shifts by electrostatic and magnetic fields are introduced; Fresne...

  3. The application of similar image retrieval in electronic commerce.

    Science.gov (United States)

    Hu, YuPing; Yin, Hua; Han, Dezhi; Yu, Fei

    2014-01-01

    Traditional online shopping platform (OSP), which searches product information by keywords, faces three problems: indirect search mode, large search space, and inaccuracy in search results. For solving these problems, we discuss and research the application of similar image retrieval in electronic commerce. Aiming at improving the network customers' experience and providing merchants with the accuracy of advertising, we design a reasonable and extensive electronic commerce application system, which includes three subsystems: image search display subsystem, image search subsystem, and product information collecting subsystem. This system can provide seamless connection between information platform and OSP, on which consumers can automatically and directly search similar images according to the pictures from information platform. At the same time, it can be used to provide accuracy of internet marketing for enterprises. The experiment shows the efficiency of constructing the system.

  4. The Application of Similar Image Retrieval in Electronic Commerce

    Directory of Open Access Journals (Sweden)

    YuPing Hu

    2014-01-01

    Full Text Available Traditional online shopping platform (OSP, which searches product information by keywords, faces three problems: indirect search mode, large search space, and inaccuracy in search results. For solving these problems, we discuss and research the application of similar image retrieval in electronic commerce. Aiming at improving the network customers’ experience and providing merchants with the accuracy of advertising, we design a reasonable and extensive electronic commerce application system, which includes three subsystems: image search display subsystem, image search subsystem, and product information collecting subsystem. This system can provide seamless connection between information platform and OSP, on which consumers can automatically and directly search similar images according to the pictures from information platform. At the same time, it can be used to provide accuracy of internet marketing for enterprises. The experiment shows the efficiency of constructing the system.

  5. The Application of Similar Image Retrieval in Electronic Commerce

    Science.gov (United States)

    Hu, YuPing; Yin, Hua; Han, Dezhi; Yu, Fei

    2014-01-01

    Traditional online shopping platform (OSP), which searches product information by keywords, faces three problems: indirect search mode, large search space, and inaccuracy in search results. For solving these problems, we discuss and research the application of similar image retrieval in electronic commerce. Aiming at improving the network customers' experience and providing merchants with the accuracy of advertising, we design a reasonable and extensive electronic commerce application system, which includes three subsystems: image search display subsystem, image search subsystem, and product information collecting subsystem. This system can provide seamless connection between information platform and OSP, on which consumers can automatically and directly search similar images according to the pictures from information platform. At the same time, it can be used to provide accuracy of internet marketing for enterprises. The experiment shows the efficiency of constructing the system. PMID:24883411

  6. Automatic solar image motion measurements. [electronic disk flux monitoring

    Science.gov (United States)

    Colgate, S. A.; Moore, E. P.

    1975-01-01

    The solar seeing image motion has been monitored electronically and absolutely with a 25 cm telescope at three sites along the ridge at the southern end of the Magdalena Mountains west of Socorro, New Mexico. The uncorrelated component of the variations of the optical flux from two points at opposite limbs of the solar disk was continually monitored in 3 frequencies centered at 0.3, 3 and 30 Hz. The frequency band of maximum signal centered at 3 Hz showed the average absolute value of image motion to be somewhat less than 2sec. The observer estimates of combined blurring and image motion were well correlated with electronically measured image motion, but the observer estimates gave a factor 2 larger value.

  7. High speed electronic imaging application in aeroballistic research

    International Nuclear Information System (INIS)

    Brown, R.R.; Parker, J.R.

    1984-01-01

    Physical and temporal restrictions imposed by modern aeroballistics have pushed imaging technology to the point where special photoconductive surfaces and high-speed support electronics are dictated. Specifications for these devices can be formulated by a methodical analysis of critical parameters and how they interact. In terms of system theory, system transfer functions and state equations can be used in optimal coupling of devices to maximize system performance. Application of these methods to electronic imaging at the Eglin Aeroballistics Research Facility is described in this report. 7 references, 14 figures, 1 table

  8. Characterization of encapsulated quantum dots via electron channeling contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Deitz, Julia I.; McComb, David W. [Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Carnevale, Santino D. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); De Graef, Marc [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Grassman, Tyler J., E-mail: grassman.5@osu.edu [Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2016-08-08

    A method for characterization of encapsulated epitaxial quantum dots (QD) in plan-view geometry using electron channeling contrast imaging (ECCI) is presented. The efficacy of the method, which requires minimal sample preparation, is demonstrated with proof-of-concept data from encapsulated (sub-surface) epitaxial InAs QDs within a GaAs matrix. Imaging of the QDs under multiple diffraction conditions is presented, establishing that ECCI can provide effectively identical visualization capabilities as conventional two-beam transmission electron microscopy. This method facilitates rapid, non-destructive characterization of sub-surface QDs giving immediate access to valuable nanostructural information.

  9. Orientation-dependent imaging of electronically excited quantum dots

    Science.gov (United States)

    Nguyen, Duc; Goings, Joshua J.; Nguyen, Huy A.; Lyding, Joseph; Li, Xiaosong; Gruebele, Martin

    2018-02-01

    We previously demonstrated that we can image electronic excitations of quantum dots by single-molecule absorption scanning tunneling microscopy (SMA-STM). With this technique, a modulated laser beam periodically saturates an electronic transition of a single nanoparticle, and the resulting tunneling current modulation ΔI(x0, y0) maps out the SMA-STM image. In this paper, we first derive the basic theory to calculate ΔI(x0, y0) in the one-electron approximation. For near-resonant tunneling through an empty orbital "i" of the nanostructure, the SMA-STM signal is approximately proportional to the electron density |φi) (x0,y0)|nudge quantum dots on the surface and roll them, thus imaging excited state electronic structure of a single quantum dot at different orientations. We use density functional theory to model ODMs at various orientations, for qualitative comparison with the SMA-STM experiment. The model demonstrates that our experimentally observed signal monitors excited states, localized by defects near the surface of an individual quantum dot. The sub-nanometer super-resolution imaging technique demonstrated here could become useful for mapping out the three-dimensional structure of excited states localized by defects within nanomaterials.

  10. Imaging the motion of electrons in 2D semiconductor heterostructures

    Science.gov (United States)

    Dani, Keshav

    Technological progress since the late 20th century has centered on semiconductor devices, such as transistors, diodes, and solar cells. At the heart of these devices, is the internal motion of electrons through semiconductor materials due to applied electric fields or by the excitation of photocarriers. Imaging the motion of these electrons would provide unprecedented insight into this important phenomenon, but requires high spatial and temporal resolution. Current studies of electron dynamics in semiconductors are generally limited by the spatial resolution of optical probes, or by the temporal resolution of electronic probes. In this talk, we combine femtosecond pump-probe techniques with spectroscopic photoemission electron microscopy to image the motion of photoexcited electrons from high-energy to low-energy states in a 2D InSe/GaAs heterostructure exhibiting a type-II band alignment. At the instant of photoexcitation, energy-resolved photoelectron images reveal a highly non-equilibrium distribution of photocarriers in space and energy. Thereafter, in response to the out-of-equilibrium photocarriers, we observe the spatial redistribution of charges, thus forming internal electric fields, bending the semiconductor bands, and finally impeding further charge transfer. By assembling images taken at different time-delays, we make a movie lasting a few tens of picoseconds of the electron transfer process in the photoexcited type-II heterostructure - a fundamental phenomenon in semiconductor devices like solar cells. Quantitative analysis and theoretical modeling of spatial variations in the video provide insight into future solar cells, electron dynamics in 2D materials, and other semiconductor devices.

  11. High-resolution imaging in the scanning transmission electron microscope

    International Nuclear Information System (INIS)

    Pennycook, S.J.; Jesson, D.E.

    1992-03-01

    The high-resolution imaging of crystalline materials in the scanning transmission electron microscopy (STEM) is reviewed with particular emphasis on the conditions under which an incoherent image can be obtained. It is shown that a high-angle annular detector can be used to break the coherence of the imaging process, in the transverse plane through the geometry of the detector, or in three dimensions if multiphonon diffuse scattering is detected. In the latter case, each atom can be treated as a highly independent source of high-angle scattering. The most effective fast electron states are therefore tightly bound s-type Bloch states. Furthermore, they add constructively for each incident angle in the coherent STEM probe, so that s states are responsible for practically the entire image contrast. Dynamical effects are largely removed, and almost perfect incoherent imaging is achieved. s states are relatively insensitive to neighboring strings, so that incoherent imaging is maintained for superlattice and interfaces, and supercell calculations are unnecessary. With an optimum probe profile, the incoherent image represents a direct image of the crystal projection, with compositional sensitivity built in through the strong dependence of the scattering cross sections on atomic number Z

  12. A high sensitivity imaging detector for electron microscopy

    International Nuclear Information System (INIS)

    Faruqi, A.R.; Andrews, H.N.; Henderson, R.

    1995-01-01

    A camera for electron microscopy based on a low readout noise cooled-CCD is described in this paper. The primary purpose of this camera is to record electron diffraction from ordered arrays of proteins but also has potential applications in imaging, electron tomography and for the automatic alignment of the electron microscope. Electrons (energy similar 120 kV) which are scattered by the specimen to form the image, which is normally recorded on film, are converted to visible photons in a polycrystalline phosphor and the resulting image is stored on the CCD (EEV 05-20, 1152 by 814, 22.5 μm square pixels). The main advantages of using CCDs include a large dynamic range, very good linearity and the possibility of immediate access to the data which is in a digitised form capable of further processing on-line during the experiment. We have built specially designed CCD ''drive'' electronics in a VME crate, interfaced to a Sun Sparcstation, for controlling the CCD operations. Data reduction programs have been installed, previously used off-line, to speed up data processing, and provide analysed data within a few minutes after the exposure. (orig.)

  13. Imaging Electron Dynamics with Ultrashort Light Pulses: A Theory Perspective

    Directory of Open Access Journals (Sweden)

    Daria Popova-Gorelova

    2018-02-01

    Full Text Available A wide range of ultrafast phenomena in various atomic, molecular and condense matter systems is governed by electron dynamics. Therefore, the ability to image electronic motion in real space and real time would provide a deeper understanding of such processes and guide developments of tools to control them. Ultrashort light pulses, which can provide unprecedented time resolution approaching subfemtosecond time scale, are perspective to achieve real-time imaging of electron dynamics. This task is challenging not only from an experimental view, but also from a theory perspective, since standard theories describing light-matter interaction in a stationary regime can provide erroneous results in an ultrafast case as demonstrated by several theoretical studies. We review the theoretical framework based on quantum electrodynamics, which has been shown to be necessary for an accurate description of time-resolved imaging of electron dynamics with ultrashort light pulses. We compare the results of theoretical studies of time-resolved nonresonant and resonant X-ray scattering, and time- and angle-resolved photoelectron spectroscopy and show that the corresponding time-resolved signals encode analogous information about electron dynamics. Thereby, the information about an electronic system provided by these time-resolved techniques is different from the information provided by their time-independent analogues.

  14. Atomic imaging using secondary electrons in a scanning transmission electron microscope: experimental observations and possible mechanisms.

    Science.gov (United States)

    Inada, H; Su, D; Egerton, R F; Konno, M; Wu, L; Ciston, J; Wall, J; Zhu, Y

    2011-06-01

    We report detailed investigation of high-resolution imaging using secondary electrons (SE) with a sub-nanometer probe in an aberration-corrected transmission electron microscope, Hitachi HD2700C. This instrument also allows us to acquire the corresponding annular dark-field (ADF) images both simultaneously and separately. We demonstrate that atomic SE imaging is achievable for a wide range of elements, from uranium to carbon. Using the ADF images as a reference, we studied the SE image intensity and contrast as functions of applied bias, atomic number, crystal tilt, and thickness to shed light on the origin of the unexpected ultrahigh resolution in SE imaging. We have also demonstrated that the SE signal is sensitive to the terminating species at a crystal surface. A possible mechanism for atomic-scale SE imaging is proposed. The ability to image both the surface and bulk of a sample at atomic-scale is unprecedented, and can have important applications in the field of electron microscopy and materials characterization. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Imaging femtosecond laser-induced electronic excitation in glass

    International Nuclear Information System (INIS)

    Mao Xianglei; Mao, Samuel S.; Russo, Richard E.

    2003-01-01

    While substantial progress has been achieved in understanding laser ablation on the nanosecond and picosecond time scales, it remains a considerable challenge to elucidate the underlying mechanisms during femtosecond laser material interactions. We present experimental observations of electronic excitation inside a wide band gap glass during single femtosecond laser pulse (100 fs, 800 nm) irradiation. Using a femtosecond time-resolved imaging technique, we measured the evolution of a laser-induced electronic plasma inside the glass and calculated the electron number density to be on the order of 10 19 cm -3

  16. Imaging of tissue sections with very slow electrons

    Energy Technology Data Exchange (ETDEWEB)

    Frank, L., E-mail: ludek@isibrno.cz [Institute of Scientific Instruments AS CR, v.v.i., Královopolská 147, 61264 Brno (Czech Republic); Nebesářová, J.; Vancová, M. [Biology Centre AS CR, v.v.i., Branišovská 31, 37005 České Budějovice (Czech Republic); Paták, A.; Müllerová, I. [Institute of Scientific Instruments AS CR, v.v.i., Královopolská 147, 61264 Brno (Czech Republic)

    2015-01-15

    The examination of thin sections of tissues with electron microscopes is an indispensable tool. Being composed of light elements, samples of living matter illuminated with electrons at the usual high energies of tens or even hundreds of kiloelectronvolts provide very low image contrasts in transmission or scanning transmission electron microscopes. Therefore, heavy metal salts are added to the specimen during preparation procedures (post-fixation with osmium tetroxide or staining). However, these procedures can modify or obscure the ultrastructural details of cells. Here we show that the energy of electrons used for the scanned transmission imaging of tissue sections can be reduced to mere hundreds or even tens of electronvolts and can produce extremely high contrast even for samples free of any metal salts. We found that when biasing a sufficiently thin tissue section sample to a high negative potential in a scanning transmission electron microscope, thereby reducing the energy of the electrons landing on the sample, and collecting the transmitted electrons with a grounded detector, we obtain a high contrast revealing structure details not enhanced by heavy atoms. Moreover, bombardment with slow electrons sensitively depolymerises the resin in which the tissue is embedded, thereby enhancing the transmitted signal with no observable loss of structure details. The use of low-energy electrons requires ultrathin sections of a thickness of less than 10 nm, but their preparation is now possible. Ultralow energy STEM provides a tool enabling the observation of very thin biological samples without any staining. This method should also be advantageous for examination of 2D crystals, thin films of polymers, polymer blends, etc. - Highlights: • Sections of a thickness below 10 nm were imaged in STEM at hundreds and tens of eV. • Image contrast grows steeply with decreasing electron energy in the STEM. • Very slow electrons provide high contrast for samples free of

  17. Superior MR images with electronically tuned and decoupled surface coils

    International Nuclear Information System (INIS)

    Ingwersen, H.; Freisen, L.; Friedrich, A.; Kess, H.; Krause, N.; Meissner, R.; Popp, W.

    1987-01-01

    In order to gain free positioning of surface coils in linearly polarized transmitting coils, it is absolutely necessary to electronically decouple both coils. For circularly polarized transmitting coils, decoupling is necessary in any case. In addition to the decoupling circuit automatic electronic tuning of the surface coils is used to gain the bast ratio of signal to noise. This combination of electronically decoupling and tuning of the surface coils yields intrinsic patient safety concerning local power deposition as well as free positioning and easy handling at the same time. Block diagrams, circuit schemes, and MR images obtained with several different surface coils are shown

  18. Imaging detectors and electronics - A view of the future

    International Nuclear Information System (INIS)

    Spieler, Helmuth

    2004-01-01

    Imaging sensors and readout electronics have made tremendous strides in the past two decades. The application of modern semiconductor fabrication techniques and the introduction of customized monolithic integrated circuits have made large scale imaging systems routine in high energy physics. This technology is now finding its way into other areas, such as space missions, synchrotron light sources, and medical imaging. I review current developments and discuss the promise and limits of new technologies. Several detector systems are described as examples of future trends. The discussion emphasizes semiconductor detector systems, but I also include recent developments for large-scale superconducting detector arrays

  19. Secondary-electron-bremsstrahlung imaging for proton therapy

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Mitsutaka; Nagao, Yuto [Takasaki Advanced Radiation Research Institute, Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki-Machi, Takasaki, Gunma (Japan); Ando, Koki; Yamamoto, Seiichi [Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-Minami, Higashi-Ku, Nagoya, Aichi (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1 Hirate-cho, Kita-Ku, Nagoya, Aichi (Japan); Kataoka, Jun [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Kawachi, Naoki [Takasaki Advanced Radiation Research Institute, Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki-Machi, Takasaki, Gunma (Japan)

    2016-10-11

    A feasibility study on an imaging technique of a therapeutic proton-beam trajectory using a gamma camera by measuring secondary electron bremsstrahlung (SEB) was performed by means of Monte Carlo simulations and a beam-irradiation experiment. From the simulation and experimental results, it was found that a significant amount of SEB yield exists between the beam-injection surface and the range position along the beam axis and the beam trajectory is clearly imaged by the SEB yield. It is concluded that the SEB imaging is a promising technique for monitoring of therapeutic proton-beam trajectories.

  20. A radiation-tolerant electronic readout system for portal imaging

    Science.gov (United States)

    Östling, J.; Brahme, A.; Danielsson, M.; Iacobaeus, C.; Peskov, V.

    2004-06-01

    A new electronic portal imaging device, EPID, is under development at the Karolinska Institutet and the Royal Institute of Technology. Due to considerable demands on radiation tolerance in the radiotherapy environment, a dedicated electronic readout system has been designed. The most interesting aspect of the readout system is that it allows to read out ˜1000 pixels in parallel, with all electronics placed outside the radiation beam—making the detector more radiation resistant. In this work we are presenting the function of a small prototype (6×100 pixels) of the electronic readout board that has been tested. Tests were made with continuous X-rays (10-60 keV) and with α particles. The results show that, without using an optimised gas mixture and with an early prototype only, the electronic readout system still works very well.

  1. Development of a new electronic neutron imaging system

    CERN Document Server

    Brenizer, J S; Gibbs, K M; Mengers, P; Stebbings, C T; Polansky, D; Rogerson, D J

    1999-01-01

    An electronic neutron imaging camera system was developed for use with thermal, epithermal, and fast neutrons in applications that include nondestructive inspection of explosives, corrosion, turbine blades, electronics, low Z components, etc. The neutron images are expected to provide information to supplement that available from X-ray tests. The primary camera image area was a 30x30 cm field-of-view with a spatial resolution approaching 1.6 line pairs/mm (lp/mm). The camera had a remotely changeable second lens to limit the field-of-view to 7.6x7.6 cm for high spatial resolution (at least 4 lp/mm) thermal neutron imaging, but neutron and light scatter will limit resolution for fast neutrons to about 0.5 lp/mm. Remote focus capability enhanced camera set-up for optimum operation. The 75 dB dynamic range camera system included sup 6 Li-based screens for imaging of thermal and epithermal neutrons and ZnS(Ag)-based screens for fast neutron imaging. The fast optics was input to a Super S-25 Gen II image intensifi...

  2. Hybrid fluorescence and electron cryo-microscopy for simultaneous electron and photon imaging.

    Science.gov (United States)

    Iijima, Hirofumi; Fukuda, Yoshiyuki; Arai, Yoshihiro; Terakawa, Susumu; Yamamoto, Naoki; Nagayama, Kuniaki

    2014-01-01

    Integration of fluorescence light and transmission electron microscopy into the same device would represent an important advance in correlative microscopy, which traditionally involves two separate microscopes for imaging. To achieve such integration, the primary technical challenge that must be solved regards how to arrange two objective lenses used for light and electron microscopy in such a manner that they can properly focus on a single specimen. To address this issue, both lateral displacement of the specimen between two lenses and specimen rotation have been proposed. Such movement of the specimen allows sequential collection of two kinds of microscopic images of a single target, but prevents simultaneous imaging. This shortcoming has been made up by using a simple optical device, a reflection mirror. Here, we present an approach toward the versatile integration of fluorescence and electron microscopy for simultaneous imaging. The potential of simultaneous hybrid microscopy was demonstrated by fluorescence and electron sequential imaging of a fluorescent protein expressed in cells and cathodoluminescence imaging of fluorescent beads. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Comparison of Electron Imaging Modes for Dimensional Measurements in the Scanning Electron Microscope.

    Science.gov (United States)

    Postek, Michael T; Vladár, András E; Villarrubia, John S; Muto, Atsushi

    2016-08-01

    Dimensional measurements from secondary electron (SE) images were compared with those from backscattered electron (BSE) and low-loss electron (LLE) images. With the commonly used 50% threshold criterion, the lines consistently appeared larger in the SE images. As the images were acquired simultaneously by an instrument with the capability to operate detectors for both signals at the same time, the differences cannot be explained by the assumption that contamination or drift between images affected the SE, BSE, or LLE images differently. Simulations with JMONSEL, an electron microscope simulator, indicate that the nanometer-scale differences observed on this sample can be explained by the different convolution effects of a beam with finite size on signals with different symmetry (the SE signal's characteristic peak versus the BSE or LLE signal's characteristic step). This effect is too small to explain the >100 nm discrepancies that were observed in earlier work on different samples. Additional modeling indicates that those discrepancies can be explained by the much larger sidewall angles of the earlier samples, coupled with the different response of SE versus BSE/LLE profiles to such wall angles.

  4. Electronic roentgenographic images in presurgical X-ray diagnostics

    International Nuclear Information System (INIS)

    Haendle, J.; Hohmann, D.; Maass, W.; Siemens A.G., Erlangen

    1981-01-01

    An essential part of radiation exposure in surgery is due to devices and results from the required radiation time interval for continuous X-ray play-back up to the point at which all diagnostically relevant information can be retrieved from the screening image. With single-image storage and short exposure times as well as instant image play-back, this superfluous i.e. redundant radiation can be avoided. The electronic X-ray image is realized by means of a laboratory prototype and evaluated in hospitals. There is a report on clinical results and new technical developments. Remarkable are: the high radiation reduction that could be obtained, the problem - free instant image technique, and especially the advantages of automated exposure in direct film settings. The positive results yield the basis for the product development. (orig./MG) [de

  5. Structure Identification in High-Resolution Transmission Electron Microscopic Images

    DEFF Research Database (Denmark)

    Vestergaard, Jacob Schack; Kling, Jens; Dahl, Anders Bjorholm

    2014-01-01

    A connection between microscopic structure and macroscopic properties is expected for almost all material systems. High-resolution transmission electron microscopy is a technique offering insight into the atomic structure, but the analysis of large image series can be time consuming. The present ...

  6. 77 FR 38829 - Certain Electronic Imaging Devices; Institution of Investigation

    Science.gov (United States)

    2012-06-29

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-850] Certain Electronic Imaging Devices; Institution of Investigation AGENCY: U.S. International Trade Commission. ACTION: Notice. SUMMARY: Notice is hereby given that a complaint was filed with the U.S. International Trade Commission on May 23, 2012...

  7. Removal of Vesicle Structures from Transmission Electron Microscope Images

    DEFF Research Database (Denmark)

    Jensen, Katrine Hommelhoff; Sigworth, Fred; Brandt, Sami Sebastian

    2015-01-01

    In this paper, we address the problem of imaging membrane proteins for single-particle cryo-electron microscopy reconstruction of the isolated protein structure. More precisely, we propose a method for learning and removing the interfering vesicle signals from the micrograph, prior to reconstruct...

  8. Sample Preparation and Imaging of Exosomes by Transmission Electron Microscopy.

    Science.gov (United States)

    Jung, Min Kyo; Mun, Ji Young

    2018-01-04

    Exosomes are nano-sized extracellular vesicles secreted by body fluids and are known to represent the characteristics of cells that secrete them. The contents and morphology of the secreted vesicles reflect cell behavior or physiological status, for example cell growth, migration, cleavage, and death. The exosomes' role may depend highly on size, and the size of exosomes varies from 30 to 300 nm. The most widely used method for exosome imaging is negative staining, while other results are based on Cryo-Transmission Electron Microscopy, Scanning Electron Microscopy, and Atomic Force Microscopy. The typical exosome's morphology assessed through negative staining is a cup-shape, but further details are not yet clear. An exosome well-characterized through structural study is necessary particular in medical and pharmaceutical fields. Therefore, function-dependent morphology should be verified by electron microscopy techniques such as labeling a specific protein in the detailed structure of exosome. To observe detailed structure, ultrathin sectioned images and negative stained images of exosomes were compared. In this protocol, we suggest transmission electron microscopy for the imaging of exosomes including negative staining, whole mount immuno-staining, block preparation, thin section, and immuno-gold labelling.

  9. Electronics Related to Nuclear Medicine Imaging Devices. Chapter 7

    Energy Technology Data Exchange (ETDEWEB)

    Ott, R. J. [Joint Department of Physics, Royal Marsden Hospital and Institute of Cancer Research, Surrey (United Kingdom); Stephenson, R. [Rutherford Appleton Laboratory, Oxfordshire (United Kingdom)

    2014-12-15

    Nuclear medicine imaging is generally based on the detection of X rays and γ rays emitted by radionuclides injected into a patient. In the previous chapter, the methods used to detect these photons were described, based most commonly on a scintillation counter although there are imaging devices that use either gas filled ionization detectors or semiconductors. Whatever device is used, nuclear medicine images are produced from a very limited number of photons, due mainly to the level of radioactivity that can be safely injected into a patient. Hence, nuclear medicine images are usually made from many orders of magnitude fewer photons than X ray computed tomography (CT) images, for example. However, as the information produced is essentially functional in nature compared to the anatomical detail of CT, the apparently poorer image quality is overcome by the nature of the information produced. The low levels of photons detected in nuclear medicine means that photon counting can be performed. Here each photon is detected and analysed individually, which is especially valuable, for example, in enabling scattered photons to be rejected. This is in contrast to X ray imaging where images are produced by integrating the flux entering the detectors. Photon counting, however, places a heavy burden on the electronics used for nuclear medicine imaging in terms of electronic noise and stability. This chapter will discuss how the signals produced in the primary photon detection process can be converted into pulses providing spatial, energy and timing information, and how this information is used to produce both qualitative and quantitative images.

  10. A Document Imaging Technique for Implementing Electronic Loan Approval Process

    Directory of Open Access Journals (Sweden)

    J. Manikandan

    2015-04-01

    Full Text Available The image processing is one of the leading technologies of computer applications. Image processing is a type of signal processing, the input for image processor is an image or video frame and the output will be an image or subset of image [1]. Computer graphics and computer vision process uses an image processing techniques. Image processing systems are used in various environments like medical fields, computer-aided design (CAD, research fields, crime investigation fields and military fields. In this paper, we proposed a document image processing technique, for establishing electronic loan approval process (E-LAP [2]. Loan approval process has been tedious process, the E-LAP system attempts to reduce the complexity of loan approval process. Customers have to login to fill the loan application form online with all details and submit the form. The loan department then processes the submitted form and then sends an acknowledgement mail via the E-LAP to the requested customer with the details about list of documents required for the loan approval process [3]. The approaching customer can upload the scanned copies of all required documents. All this interaction between customer and bank take place using an E-LAP system.

  11. Time-resolved tomographic images of a relativistic electron beam

    International Nuclear Information System (INIS)

    Koehler, H.A.; Jacoby, B.A.; Nelson, M.

    1984-07-01

    We obtained a sequential series of time-resolved tomographic two-dimensional images of a 4.5-MeV, 6-kA, 30-ns electron beam. Three linear fiber-optic arrays of 30 or 60 fibers each were positioned around the beam axis at 0 0 , 61 0 , and 117 0 . The beam interacting with nitrogen at 20 Torr emitted light that was focused onto the fiber arrays and transmitted to a streak camera where the data were recorded on film. The film was digitized, and two-dimensional images were reconstructed using the maximum-entropy tomographic technique. These images were then combined to produce an ultra-high-speed movie of the electron-beam pulse

  12. Analysis of patient setup accuracy using electronic portal imaging device

    International Nuclear Information System (INIS)

    Onogi, Yuzo; Aoki, Yukimasa; Nakagawa, Keiichi

    1996-01-01

    Radiation therapy is performed in many fractions, and accurate patient setup is very important. This is more significant nowadays because treatment planning and radiation therapy are more precisely performed. Electronic portal imaging devices and automatic image comparison algorithms let us analyze setup deviations quantitatively. With such in mind we developed a simple image comparison algorithm. Using 2459 electronic verification images (335 ports, 123 treatment sites) generated during the past three years at our institute, we evaluated the results of the algorithm, and analyzed setup deviations according to the area irradiated, use of a fixing device (shell), and arm position. Calculated setup deviation was verified visually and their fitness was classified into good, fair, bad, and incomplete. The result was 40%, 14%, 22%, 24% respectively. Using calculated deviations classified as good (994 images), we analyzed setup deviations. Overall setup deviations described in 1 SD along axes x, y, z, was 1.9 mm, 2.5 mm, 1.7 mm respectively. We classified these deviations into systematic and random components, and found that random error was predominant in our institute. The setup deviations along axis y (cranio-caudal direction) showed larger distribution when treatment was performed with the shell. Deviations along y (cranio-caudal) and z (anterior-posterior) had larger distribution when treatment occurred with the patient's arm elevated. There was a significant time-trend error, whose deviations become greater with time. Within all evaluated ports, 30% showed a time-trend error. Using an electronic portal imaging device and automatic image comparison algorithm, we are able to analyze setup deviations more precisely and improve setup method based on objective criteria. (author)

  13. Electron temperature fluctuation in the HT-7 tokamak plasma observed by electron cyclotron emission imaging

    International Nuclear Information System (INIS)

    Xiao-Yuan, Xu; Jun, Wang; Yi, Yu; Yi-Zhi, Wen; Chang-Xuan, Yu; Wan-Dong, Liu; Bao-Nian, Wan; Xiang, Gao; Luhmann, N. C.; Domier, C. W.; Wang, Jian; Xia, Z. G.; Shen, Zuowei

    2009-01-01

    The fluctuation of the electron temperature has been measured by using the electron cyclotron emission imaging in the Hefei Tokamak-7 (HT-7) plasma. The electron temperature fluctuation with a broadband spectrum shows that it propagates in the electron diamagnetic drift direction, and the mean poloidal wave-number k-bar θ is calculated to be about 1.58 cm −1 , or k-bar θρ s thickapprox 0.34. It indicates that the fluctuation should come from the electron drift wave turbulence. The linear global scaling of the electron temperature fluctuation with the gradient of electron temperature is consistent with the mixing length scale qualitatively. Evolution of spectrum of the fluctuation during the sawtooth oscillation phases is investigated, and the fluctuation is found to increase with the gradient of electron temperature increasing during most phases of the sawtooth oscillation. The results indicate that the electron temperature gradient is probably the driver of the fluctuation enhancement. The steady heat flux driven by electron temperature fluctuation is estimated and compared with the results from power balance estimation. (fluids, plasmas and electric discharges)

  14. Imaging single atoms using secondary electrons with an aberration-corrected electron microscope.

    Science.gov (United States)

    Zhu, Y; Inada, H; Nakamura, K; Wall, J

    2009-10-01

    Aberration correction has embarked on a new frontier in electron microscopy by overcoming the limitations of conventional round lenses, providing sub-angstrom-sized probes. However, improvement of spatial resolution using aberration correction so far has been limited to the use of transmitted electrons both in scanning and stationary mode, with an improvement of 20-40% (refs 3-8). In contrast, advances in the spatial resolution of scanning electron microscopes (SEMs), which are by far the most widely used instrument for surface imaging at the micrometre-nanometre scale, have been stagnant, despite several recent efforts. Here, we report a new SEM, with aberration correction, able to image single atoms by detecting electrons emerging from its surface as a result of interaction with the small probe. The spatial resolution achieved represents a fourfold improvement over the best-reported resolution in any SEM (refs 10-12). Furthermore, we can simultaneously probe the sample through its entire thickness with transmitted electrons. This ability is significant because it permits the selective visualization of bulk atoms and surface ones, beyond a traditional two-dimensional projection in transmission electron microscopy. It has the potential to revolutionize the field of microscopy and imaging, thereby opening the door to a wide range of applications, especially when combined with simultaneous nanoprobe spectroscopy.

  15. Imaging quasiperiodic electronic states in a synthetic Penrose tiling

    Science.gov (United States)

    Collins, Laura C.; Witte, Thomas G.; Silverman, Rochelle; Green, David B.; Gomes, Kenjiro K.

    2017-06-01

    Quasicrystals possess long-range order but lack the translational symmetry of crystalline solids. In solid state physics, periodicity is one of the fundamental properties that prescribes the electronic band structure in crystals. In the absence of periodicity and the presence of quasicrystalline order, the ways that electronic states change remain a mystery. Scanning tunnelling microscopy and atomic manipulation can be used to assemble a two-dimensional quasicrystalline structure mapped upon the Penrose tiling. Here, carbon monoxide molecules are arranged on the surface of Cu(111) one at a time to form the potential landscape that mimics the ionic potential of atoms in natural materials by constraining the electrons in the two-dimensional surface state of Cu(111). The real-space images reveal the presence of the quasiperiodic order in the electronic wave functions and the Fourier analysis of our results links the energy of the resonant states to the local vertex structure of the quasicrystal.

  16. Low energy electron microscopy imaging using Medipix2 detector

    International Nuclear Information System (INIS)

    Sikharulidze, I.; Gastel, R. van; Schramm, S.; Abrahams, J.P.; Poelsema, B.; Tromp, R.M.; Molen, S.J. van der

    2011-01-01

    Low Energy Electron Microscopy (LEEM) and Photo-Emission Electron Microscopy (PEEM) predominantly use a combination of microchannel plate (MCP), phosphor screen and optical camera to record images formed by 10-20 keV electrons. We have tested the performance of a LEEM/PEEM instrument with a Medipix2 hybrid pixel detector using an Ir(1 1 1) sample with graphene flakes grown on its surface. We find that Medipix2 offers a number of advantages over the MCP. The adjustable threshold settings allow Medipix2 to operate as a noiseless detector, offering an improved signal-to-noise ratio for the same amount of signal compared to the MCP. At the same magnification Medipix2 images exhibit superior resolution and can handle significantly higher electron current densities than an MCP, offering the prospect of substantially higher frame rates in LEEM imaging. These factors make Medipix2 an excellent candidate to become the detector of choice for LEEM/PEEM applications.

  17. Low energy electron microscopy imaging using Medipix2 detector

    Energy Technology Data Exchange (ETDEWEB)

    Sikharulidze, I., E-mail: irakli@chem.leidenuniv.nl [Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300RA Leiden (Netherlands); Gastel, R. van [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Schramm, S. [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands); Abrahams, J.P. [Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300RA Leiden (Netherlands); Poelsema, B. [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Tromp, R.M. [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands); IBM Research Division, T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Molen, S.J. van der [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands)

    2011-05-15

    Low Energy Electron Microscopy (LEEM) and Photo-Emission Electron Microscopy (PEEM) predominantly use a combination of microchannel plate (MCP), phosphor screen and optical camera to record images formed by 10-20 keV electrons. We have tested the performance of a LEEM/PEEM instrument with a Medipix2 hybrid pixel detector using an Ir(1 1 1) sample with graphene flakes grown on its surface. We find that Medipix2 offers a number of advantages over the MCP. The adjustable threshold settings allow Medipix2 to operate as a noiseless detector, offering an improved signal-to-noise ratio for the same amount of signal compared to the MCP. At the same magnification Medipix2 images exhibit superior resolution and can handle significantly higher electron current densities than an MCP, offering the prospect of substantially higher frame rates in LEEM imaging. These factors make Medipix2 an excellent candidate to become the detector of choice for LEEM/PEEM applications.

  18. Prospective clinical evaluation of an electronic portal imaging device

    International Nuclear Information System (INIS)

    Michalski, Jeff M.; Graham, Mary V.; Bosch, Walter R.; Wong, John; Gerber, Russell L.; Cheng, Abel; Tinger, Alfred; Valicenti, Richard K.

    1996-01-01

    Purpose: To determine whether the clinical implementation of an electronic portal imaging device can improve the precision of daily external beam radiotherapy. Methods and Materials: In 1991, an electronic portal imaging device was installed on a dual energy linear accelerator in our clinic. After training the radiotherapy technologists in the acquisition and evaluation of portal images, we performed a randomized study to determine whether online observation, interruption, and intervention would result in more precise daily setup. The patients were randomized to one of two groups: those whose treatments were actively monitored by the radiotherapy technologists and those that were imaged but not monitored. The treating technologists were instructed to correct the following treatment errors: (a) field placement error (FPE) > 1 cm; (b) incorrect block; (c) incorrect collimator setting; (d) absent customized block. Time of treatment delivery was recorded by our patient tracking and billing computers and compared to a matched set of patients not participating in the study. After the patients radiation therapy course was completed, an offline analysis of the patient setup error was planned. Results: Thirty-two patients were treated to 34 anatomical sites in this study. In 893 treatment sessions, 1,873 fields were treated (1,089 fields monitored and 794 fields unmonitored). Ninety percent of the treated fields had at least one image stored for offline analysis. Eighty-seven percent of these images were analyzed offline. Of the 1,011 fields imaged in the monitored arm, only 14 (1.4%) had an intervention recorded by the technologist. Despite infrequent online intervention, offline analysis demonstrated that the incidence of FPE > 10 mm in the monitored and unmonitored groups was 56 out of 881 (6.1%) and 95 out of 595 (11.2%), respectively; p 10 mm was confined to the pelvic fields. The time to treat patients in this study was 10.78 min (monitored) and 10.10 min (unmonitored

  19. Pico-femtosecond image-tube photography in quantum electronics

    International Nuclear Information System (INIS)

    Schelev, M Ya

    2001-01-01

    The possibility of experimental achievement of the time resolution of image-converter tubes (ICTs) corresponding to the theoretical limit of 10 fs is considered as applied to quantum electronics problems. A new generation of ICTs with a temporal resolution of 200 - 500 fs has been developed for recording femtosecond laser radiation. The entirely new devices based on time-analysing ICTs such as femtosecond photoelectronic diffractometers, have been created for studying the dynamics of phase transitions in substances using diffrac-tion of electrons with energies ranging from 20 to 40 keV. (femtosecond technologies)

  20. Exploding and Imaging of Electron Bubbles in Liquid Helium

    Science.gov (United States)

    Yadav, Neha; Vadakkumbatt, Vaisakh; Maris, Humphrey J.; Ghosh, Ambarish

    2017-06-01

    An electron bubble in liquid helium-4 under the saturated vapor pressure becomes unstable and explodes if the pressure becomes more negative than -1.9 bars. In this paper, we use focused ultrasound to explode electron bubbles. We then image at 30,000 frames per second the growth and subsequent collapse of the bubbles. We find that bubbles can grow to as large as 1 mm in diameter within 2 ms after the cavitation event. We examine the relation between the maximum size of the bubble and the lifetime and find good agreement with the experimental results.

  1. Imaging and Measuring Electron Beam Dose Distributions Using Holographic Interferometry

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1975-01-01

    Holographic interferometry was used to image and measure ionizing radiation depth-dose and isodose distributions in transparent liquids. Both broad and narrowly collimated electron beams from accelerators (2–10 MeV) provided short irradiation times of 30 ns to 0.6 s. Holographic images...... and measurements of absorbed dose distributions were achieved in liquids of various densities and thermal properties and in water layers thinner than the electron range and with backings of materials of various densities and atomic numbers. The lowest detectable dose in some liquids was of the order of a few k......Rad. The precision limits of the measurement of dose were found to be ±4%. The procedure was simple and the holographic equipment stable and compact, thus allowing experimentation under routine laboratory conditions and limited space....

  2. Immunocytochemistry by electron spectroscopic imaging using a homogeneously boronated peptide.

    Science.gov (United States)

    Kessels, M M; Qualmann, B; Klobasa, F; Sierralta, W D

    1996-05-01

    A linear all-L-oligopeptide containing five carboranyl amino acids (corresponding to 50 boron atoms) was synthesized and specifically attached to the free thiol group of monovalent antibody fragments F(ab)'. The boronated immunoreagent was used for the direct post-embedding detection of somatotrophic hormone in ultrathin sections of porcine pituitary embedded in Spurr resin. The specific boron-labelling of secretory vesicles in somatotrophs was detected by electron spectroscopic imaging and confirmed by conventional immunogold labelling run in parallel. In comparison with immunogold, boron-labelled F(ab)'-fragments showed higher tagging frequencies, as was expected; the small uncharged immunoreagents have an elongated shape and carry the antigen-combining structure and the detection tag at opposite ends, thus allowing for high spatial resolution in electron spectroscopic imaging.

  3. Electronic photography: a new age of medical imaging?

    Science.gov (United States)

    Tübergen, D; Manegold, B C

    1993-07-01

    This is a critical overview of present conceptions of the introduction of electronic photography in medicine. It is not a complete list of products, rather it is a description of how the requirements of the physician have influenced medical illustration in the past and will continue to do so in the future. Video systems are widely used in medicine. Besides the learning and teaching of effects of television, minimal invasive surgery (MIS) has become reality through endoscopy, rapidly accepted worldwide. Documentation of endoscopic procedures and their effects is becoming routine. Therefore, the conversion of complex optical information into binary units is a logical development to save space for storage. The reproduction, storage and transfer of detailed images is already realized by digital camera systems, photo CD, scanners and picture archiving and communicating system (PACS). Now electronic imaging in medicine has to be regarded as a matter of routine. The real impact of accelerated editing will be shown in the future.

  4. Development of a new electronic neutron imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Brenizer, J.S. [Department of Mechanical, Aerospace and Nuclear Engineering, Thornton Hall, University of Virginia, Charlottesville, VA 22903-2442 (United States); Berger, H. [Industrial Quality, Inc., Gaithersburg, MD (United States); Gibbs, K.M. [Industrial Quality, Inc., Gaithersburg, MD (United States); Mengers, P. [Paultek Systems, Inc., Nevada City, CA (United States); Stebbings, C.T. [Department of Mechanical, Aerospace and Nuclear Engineering, Thornton Hall, University of Virginia, Charlottesville, VA 22903-2442 (United States); Polansky, D. [Industrial Quality, Inc., Gaithersburg, MD (United States); Rogerson, D.J. [Naval Air Warfare Center, China Lake, CA (United States)

    1999-11-03

    An electronic neutron imaging camera system was developed for use with thermal, epithermal, and fast neutrons in applications that include nondestructive inspection of explosives, corrosion, turbine blades, electronics, low Z components, etc. The neutron images are expected to provide information to supplement that available from X-ray tests. The primary camera image area was a 30x30 cm field-of-view with a spatial resolution approaching 1.6 line pairs/mm (lp/mm). The camera had a remotely changeable second lens to limit the field-of-view to 7.6x7.6 cm for high spatial resolution (at least 4 lp/mm) thermal neutron imaging, but neutron and light scatter will limit resolution for fast neutrons to about 0.5 lp/mm. Remote focus capability enhanced camera set-up for optimum operation. The 75 dB dynamic range camera system included {sup 6}Li-based screens for imaging of thermal and epithermal neutrons and ZnS(Ag)-based screens for fast neutron imaging. The fast optics was input to a Super S-25 Gen II image intensifier, fiber optically coupled to a 1134 (h)x486 (v) frame transfer CCD camera. The camera system was designed to be compatible with a Navy-sponsored accelerator neutron source. The planned neutron source is an RF quadrupole accelerator that will provide a fast neutron flux of 10{sup 7} n/cm{sup 2}-s (at a source distance of 1 m) at an energy of about 2.2 MeV and a thermal neutron flux of 10{sup 6} n/cm{sup 2}-s at a source L/D ratio of 30. The electronic camera produced good quality real-time images at these neutron levels. On-chip integration could be used to improve image quality for low flux situations. The camera and accelerator combination provided a useful non-reactor neutron inspection system.

  5. Precision crystal alignment for high-resolution electron microscope imaging

    International Nuclear Information System (INIS)

    Wood, G.J.; Beeching, M.J.

    1990-01-01

    One of the more difficult tasks involved in obtaining quality high-resolution electron micrographs is the precise alignment of a specimen into the required zone. The current accepted procedure, which involves changing to diffraction mode and searching for symmetric point diffraction pattern, is insensitive to small amounts of misalignment and at best qualitative. On-line analysis of the fourier space representation of the image, both for determining and correcting crystal tilt, is investigated. 8 refs., 42 figs

  6. Standards for electronic imaging for graphic arts systems

    Science.gov (United States)

    Dunn, S. T.; Dunn, Patrice M.

    1991-03-01

    This paper examines the development of electronic imaging standards by and for the graphic arts industry. Taken collectively this body of work is referred to as Digital Data Exchange Standards (DDES). Because these standards are being driven by market and user requirements there are several fundamental guiding principles to their development. This paper examines these and provides an overview to the technical developments undertaken by the accredited graphic arts industry standards committees to date.

  7. Low energy electron point source microscopy: beyond imaging

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Andre; Goelzhaeuser, Armin [Physics of Supramolecular Systems and Surfaces, University of Bielefeld, Postfach 100131, 33501 Bielefeld (Germany)

    2010-09-01

    Low energy electron point source (LEEPS) microscopy has the capability to record in-line holograms at very high magnifications with a fairly simple set-up. After the holograms are numerically reconstructed, structural features with the size of about 2 nm can be resolved. The achievement of an even higher resolution has been predicted. However, a number of obstacles are known to impede the realization of this goal, for example the presence of electric fields around the imaged object, electrostatic charging or radiation induced processes. This topical review gives an overview of the achievements as well as the difficulties in the efforts to shift the resolution limit of LEEPS microscopy towards the atomic level. A special emphasis is laid on the high sensitivity of low energy electrons to electrical fields, which limits the structural determination of the imaged objects. On the other hand, the investigation of the electrical field around objects of known structure is very useful for other tasks and LEEPS microscopy can be extended beyond the task of imaging. The determination of the electrical resistance of individual nanowires can be achieved by a proper analysis of the corresponding LEEPS micrographs. This conductivity imaging may be a very useful application for LEEPS microscopes. (topical review)

  8. SEGMENTATION OF MITOCHONDRIA IN ELECTRON MICROSCOPY IMAGES USING ALGEBRAIC CURVES.

    Science.gov (United States)

    Seyedhosseini, Mojtaba; Ellisman, Mark H; Tasdizen, Tolga

    2013-01-01

    High-resolution microscopy techniques have been used to generate large volumes of data with enough details for understanding the complex structure of the nervous system. However, automatic techniques are required to segment cells and intracellular structures in these multi-terabyte datasets and make anatomical analysis possible on a large scale. We propose a fully automated method that exploits both shape information and regional statistics to segment irregularly shaped intracellular structures such as mitochondria in electron microscopy (EM) images. The main idea is to use algebraic curves to extract shape features together with texture features from image patches. Then, these powerful features are used to learn a random forest classifier, which can predict mitochondria locations precisely. Finally, the algebraic curves together with regional information are used to segment the mitochondria at the predicted locations. We demonstrate that our method outperforms the state-of-the-art algorithms in segmentation of mitochondria in EM images.

  9. Image enhancement in photoemission electron microscopy by means of imaging time-of-flight analysis

    International Nuclear Information System (INIS)

    Oelsner, A.; Krasyuk, A.; Fecher, G.H.; Schneider, C.M.; Schoenhense, G.

    2004-01-01

    Photoemission electron microscopy (PEEM) is widely used in combination with synchrotron sources as a powerful tool to observe chemical and magnetic properties of metal and semiconductor surfaces. Presently, the resolution limit of these instruments using soft-X-ray excitation is limited to about 50 nm, because of the chromatic aberration of the electron optics used. Various sophisticated approaches have thus been reported for enhancing the spatial resolution in photoemission electron microscopy. This work demonstrates the use of a simple imaging energy filter based on electron time-of-flight (ToF) selection. The spatial resolution could be improved dramatically, even though the instrument was optimized using a rather large contrast aperture of 50 μm. A special (x, y, t)-resolving delayline detector was used as the imaging unit of this ToF-PEEM. It is operated in phase with the time structure of the synchrotron source, cutting time intervals from the raw image-forming data set in order to reduce the electron energy width contributing to the final images

  10. Neural Network for Nanoscience Scanning Electron Microscope Image Recognition.

    Science.gov (United States)

    Modarres, Mohammad Hadi; Aversa, Rossella; Cozzini, Stefano; Ciancio, Regina; Leto, Angelo; Brandino, Giuseppe Piero

    2017-10-16

    In this paper we applied transfer learning techniques for image recognition, automatic categorization, and labeling of nanoscience images obtained by scanning electron microscope (SEM). Roughly 20,000 SEM images were manually classified into 10 categories to form a labeled training set, which can be used as a reference set for future applications of deep learning enhanced algorithms in the nanoscience domain. The categories chosen spanned the range of 0-Dimensional (0D) objects such as particles, 1D nanowires and fibres, 2D films and coated surfaces, and 3D patterned surfaces such as pillars. The training set was used to retrain on the SEM dataset and to compare many convolutional neural network models (Inception-v3, Inception-v4, ResNet). We obtained compatible results by performing a feature extraction of the different models on the same dataset. We performed additional analysis of the classifier on a second test set to further investigate the results both on particular cases and from a statistical point of view. Our algorithm was able to successfully classify around 90% of a test dataset consisting of SEM images, while reduced accuracy was found in the case of images at the boundary between two categories or containing elements of multiple categories. In these cases, the image classification did not identify a predominant category with a high score. We used the statistical outcomes from testing to deploy a semi-automatic workflow able to classify and label images generated by the SEM. Finally, a separate training was performed to determine the volume fraction of coherently aligned nanowires in SEM images. The results were compared with what was obtained using the Local Gradient Orientation method. This example demonstrates the versatility and the potential of transfer learning to address specific tasks of interest in nanoscience applications.

  11. Electron imaging with Medipix2 hybrid pixel detector

    CERN Document Server

    McMullan, G; Chen, S; Henderson, R; Llopart, X; Summerfield, C; Tlustos, L; Faruqi, A R

    2007-01-01

    The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 μm×55 μm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 μm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach 85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach 35% of that expected for a perfect detector (4/π2). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/π). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected v...

  12. Electron imaging with Medipix2 hybrid pixel detector

    International Nuclear Information System (INIS)

    McMullan, G.; Cattermole, D.M.; Chen, S.; Henderson, R.; Llopart, X.; Summerfield, C.; Tlustos, L.; Faruqi, A.R.

    2007-01-01

    The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 μmx55 μm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 μm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach ∼85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach ∼35% of that expected for a perfect detector (4/π 2 ). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/π). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected values for the MTF and DQE as a function of the threshold energy. The good agreement between theory and experiment allows suggestions for further improvements to be made with confidence. The present detector is already very useful for experiments that require a high DQE at very low doses

  13. Electron imaging with Medipix2 hybrid pixel detector.

    Science.gov (United States)

    McMullan, G; Cattermole, D M; Chen, S; Henderson, R; Llopart, X; Summerfield, C; Tlustos, L; Faruqi, A R

    2007-01-01

    The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 microm x 55 microm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 microm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach approximately 85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach approximately 35% of that expected for a perfect detector (4/pi(2)). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/pi). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected values for the MTF and DQE as a function of the threshold energy. The good agreement between theory and experiment allows suggestions for further improvements to be made with confidence. The present detector is already very useful for experiments that require a high DQE at very low doses.

  14. Interlaboratory comparison of dicentric chromosome assay using electronically transmitted images

    International Nuclear Information System (INIS)

    Garcia, O.; Di Giorgio, M.; Vallerga, M. B.; Radl, A.; Taja, M. R.; Seoane, A.; De Luca, J.; Stuck Oliveira, M.; Valdivia, P.; Lamadrid, A. I.; Gonzalez, J. E.; Romero, I.; Mandina, T.; Pantelias, G.; Terzoudi, G.; Guerrero-Carbajal, C.; Arceo Maldonado, C.; Espinoza, M.; Oliveros, N.; Martinez-Lopez, W.; Di Tomaso, M. V.; Mendez-Acuna, L.; Puig, R.; Roy, L.; Barquinero, J. F.

    2013-01-01

    The bottleneck in data acquisition during biological dosimetry based on a dicentric assay is the need to score dicentrics in a large number of lymphocytes. One way to increase the capacity of a given laboratory is to use the ability of skilled operators from other laboratories. This can be done using image analysis systems and distributing images all around the world. Two exercises were conducted to test the efficiency of such an approach involving 10 laboratories. During the first exercise (E1), the participant laboratories analysed the same images derived from cells exposed to 0.5 and 3 Gy; 100 images were sent to all participants for both doses. Whatever the dose, only about half of the cells were complete with well-spread metaphases suitable for analysis. A coefficient of variation (CV) on the standard deviation of 15 % was obtained for both doses. The trueness was better for 3 Gy (0.6 %) than for 0.5 Gy (37.8 %). The number of estimated doses classified as satisfactory according to the z-score was 3 at 0.5 Gy and 8 at 3 Gy for 10 dose estimations. In the second exercise, an emergency situation was tested, each laboratory was required to score a different set of 50 images in 2 d extracted from 500 downloaded images derived from cells exposed to 0.5 Gy. Then the remaining 450 images had to be scored within a week. Using 50 different images, the CV on the estimated doses (79.2 %) was not as good as in E1, probably associated to a lower number of cells analysed (50 vs. 100) or from the fact that laboratories analysed a different set of images. The trueness for the dose was better after scoring 500 cells (22.5 %) than after 50 cells (26.8 %). For the 10 dose estimations, the number of doses classified as satisfactory according to the z-score was 9, for both 50 and 500 cells. Overall, the results obtained support the feasibility of networking using electronically transmitted images. However, before its implementation some issues should be elucidated, such as the

  15. High-resolution, high-throughput imaging with a multibeam scanning electron microscope.

    Science.gov (United States)

    Eberle, A L; Mikula, S; Schalek, R; Lichtman, J; Knothe Tate, M L; Zeidler, D

    2015-08-01

    Electron-electron interactions and detector bandwidth limit the maximal imaging speed of single-beam scanning electron microscopes. We use multiple electron beams in a single column and detect secondary electrons in parallel to increase the imaging speed by close to two orders of magnitude and demonstrate imaging for a variety of samples ranging from biological brain tissue to semiconductor wafers. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  16. Suppression of COTR in electron beam imaging diagnosis at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Minjie

    2012-05-15

    The Free-Electron Laser in Hamburg (FLASH) demands electron beams with high peak current to generate high-brilliant, coherent X-ray pulses. Magnetic chicanes are used for longitudinal compression of the electron bunches to achieve the required high peak current. During bunch compression process, microstructures with a modulation length comparable to the visible light can be induced inside the bunch. This leads to coherent emission of optical transition radiation (OTR), which may impede the widely used beam diagnostic based on OTR imaging. In this thesis, two methods of using incoherent scintillation light are proposed to circumvent the problem of coherence effects in beam imaging diagnostics. The method of temporal separation has been proved experimentally to have successfully suppressed coherence effects. The longitudinal beam profiles measured using this method are in good agreement with reference measurements, verifying further the reliability of the method. The method of spatial separation has been investigated in preparation studies, from which an improved experimental setup has been designed.

  17. Suppression of COTR in electron beam imaging diagnosis at FLASH

    International Nuclear Information System (INIS)

    Yan, Minjie

    2011-12-01

    The Free-Electron Laser in Hamburg (FLASH) demands electron beams with high peak current to generate high-brilliant, coherent X-ray pulses. Magnetic chicanes are used for longitudinal compression of the electron bunches to achieve the required high peak current. During bunch compression process, microstructures with a modulation length comparable to the visible light can be induced inside the bunch. This leads to coherent emission of optical transition radiation (OTR), which may impede the widely used beam diagnostic based on OTR imaging. In this thesis, two methods of using incoherent scintillation light are proposed to circumvent the problem of coherence effects in beam imaging diagnostics. The method of temporal separation has been proved experimentally to have successfully suppressed coherence effects. The longitudinal beam profiles measured using this method are in good agreement with reference measurements, verifying further the reliability of the method. The method of spatial separation has been investigated in preparation studies, from which an improved experimental setup has been designed.

  18. Nanodiamond Landmarks for Subcellular Multimodal Optical and Electron Imaging

    Science.gov (United States)

    Zurbuchen, Mark A.; Lake, Michael P.; Kohan, Sirus A.; Leung, Belinda; Bouchard, Louis-S.

    2013-01-01

    There is a growing need for biolabels that can be used in both optical and electron microscopies, are non-cytotoxic, and do not photobleach. Such biolabels could enable targeted nanoscale imaging of sub-cellular structures, and help to establish correlations between conjugation-delivered biomolecules and function. Here we demonstrate a sub-cellular multi-modal imaging methodology that enables localization of inert particulate probes, consisting of nanodiamonds having fluorescent nitrogen-vacancy centers. These are functionalized to target specific structures, and are observable by both optical and electron microscopies. Nanodiamonds targeted to the nuclear pore complex are rapidly localized in electron-microscopy diffraction mode to enable “zooming-in” to regions of interest for detailed structural investigations. Optical microscopies reveal nanodiamonds for in-vitro tracking or uptake-confirmation. The approach is general, works down to the single nanodiamond level, and can leverage the unique capabilities of nanodiamonds, such as biocompatibility, sensitive magnetometry, and gene and drug delivery. PMID:24036840

  19. An image correlation procedure for digitally reconstructed radiographs and electronic portal images

    International Nuclear Information System (INIS)

    Dong, Lei; Boyer, Arthur L.

    1995-01-01

    Purpose: To study a procedure that uses megavoltage digitally reconstructed radiographs (DRRs) calculated from patient's three-dimensional (3D) computed tomography (CT) data as a reference image for correlation with on-line electronic portal images (EPIs) to detect patient setup errors. Methods and Materials: Megavoltage DRRs were generated by ray tracing through a modified volumetric CT data set in which CT numbers were converted into linear attenuation coefficients for the therapeutic beam energy. The DRR transmission image was transformed to the grayscale window of the EPI by a histogram-matching technique. An alternative approach was to calibrate the transmission DRR using a measured response curve of the electronic portal imaging device (EPID). This forces the calculated transmission fluence values to be distributed in the same range as that of the EPID image. A cross-correlation technique was used to determine the degree of alignment of the patient anatomy found in the EPID image relative to the reference DRR. Results: Phantom studies demonstrated that the correlation procedure had a standard deviation of 0.5 mm and 0.5 deg. in aligning translational shifts and in-plane rotations. Systematic errors were found between a reference DRR and a reference EPID image. The automated grayscale image-correlation process was completed within 3 s on a workstation computer or 12 s on a PC. Conclusion: The alignment procedure allows the direct comparison of a patient's treatment portal designed with a 3D planning computer with a patient's on-line portal image acquired at the treatment unit. The image registration process is automated to the extent that it requires minimal user intervention, and it is fast and accurate enough for on-line clinical applications

  20. Low-kilovolt coherent electron diffractive imaging instrument based on a single-atom electron source

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chun-Yueh [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Chang, Wei-Tse; Chen, Yi-Sheng; Hwu, En-Te; Chang, Chia-Seng; Hwang, Ing-Shouh, E-mail: ishwang@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Hsu, Wei-Hao [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2016-03-15

    In this work, a transmission-type, low-kilovolt coherent electron diffractive imaging instrument was constructed. It comprised a single-atom field emitter, a triple-element electrostatic lens, a sample holder, and a retractable delay line detector to record the diffraction patterns at different positions behind the sample. It was designed to image materials thinner than 3 nm. The authors analyzed the asymmetric triple-element electrostatic lens for focusing the electron beams and achieved a focused beam spot of 87 nm on the sample plane at the electron energy of 2 kV. High-angle coherent diffraction patterns of a suspended graphene sample corresponding to (0.62 Å){sup −1} were recorded. This work demonstrated the potential of coherent diffractive imaging of thin two-dimensional materials, biological molecules, and nano-objects at a voltage between 1 and 10 kV. The ultimate goal of this instrument is to achieve atomic resolution of these materials with high contrast and little radiation damage.

  1. Imaging and Quantification of Extracellular Vesicles by Transmission Electron Microscopy.

    Science.gov (United States)

    Linares, Romain; Tan, Sisareuth; Gounou, Céline; Brisson, Alain R

    2017-01-01

    Extracellular vesicles (EVs) are cell-derived vesicles that are present in blood and other body fluids. EVs raise major interest for their diverse physiopathological roles and their potential biomedical applications. However, the characterization and quantification of EVs constitute major challenges, mainly due to their small size and the lack of methods adapted for their study. Electron microscopy has made significant contributions to the EV field since their initial discovery. Here, we describe the use of two transmission electron microscopy (TEM) techniques for imaging and quantifying EVs. Cryo-TEM combined with receptor-specific gold labeling is applied to reveal the morphology, size, and phenotype of EVs, while their enumeration is achieved after high-speed sedimentation on EM grids.

  2. Programmable trigger for electron pairs in ring image Cherenkov counters

    International Nuclear Information System (INIS)

    Glab, J.; Baur, R.; Manner, R.

    1990-01-01

    This paper describes a programmable trigger processor for the recognition of Cherenkov rings in a RICH counter. It identifies open electron pairs and suppresses close conversion and Dalitz pairs within 20 μs. More generally, the system can be used for correlating pixel images with pattern masks in order to locate all relatively well defined patterns of a certain type. The trigger processor consists of a systolic processor array of 160 x 176, i.e., 28,160 identical processing elements (PEs) that filter out open electron pairs, and a pseudo adder array that determines whether there was at least one such pair. The processor array is assembled of 20 x 22 VLSI chips containing 8 x 8 PEs each. The semi-custom chip has been developed in 2 μ CMOS standard cell technology

  3. A simple way to obtain backscattered electron images in a scanning transmission electron microscope.

    Science.gov (United States)

    Tsuruta, Hiroki; Tanaka, Shigeyasu; Tanji, Takayoshi; Morita, Chiaki

    2014-08-01

    We have fabricated a simple detector for backscattered electrons (BSEs) and incorporated the detector into a scanning transmission electron microscope (STEM) sample holder. Our detector was made from a 4-mm(2) Si chip. The fabrication procedure was easy, and similar to a standard transmission electron microscopy (TEM) sample thinning process based on ion milling. A TEM grid containing particle objects was fixed to the detector with a silver paste. Observations were carried out using samples of Au and latex particles at 75 and 200 kV. Such a detector provides an easy way to obtain BSE images in an STEM. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Pattern recognition trigger electronics for an imaging atmospheric Cherenkov telescope

    International Nuclear Information System (INIS)

    Bradbury, S.M.; Rose, H.J.

    2002-01-01

    For imaging atmospheric Cherenkov telescopes, which aim to detect electromagnetic air showers with cameras consisting of several hundred photomultiplier pixels, the single pixel trigger rate is dominated by fluctuations in night sky brightness and by ion feedback in the photomultipliers. Pattern recognition trigger electronics may be used to reject night sky background images, thus reducing the data rate to a manageable level. The trigger system described here detects patterns of 2, 3 or 4 adjacent pixel signals within a 331 pixel camera and gives a positive trigger decision in 65 ns. The candidate pixel pattern is compared with the contents of a pre-programmed memory. With the trigger decision timing controlled by a fixed delay the time-jitter inherent in the use of programmable gate arrays is avoided. This system is now in routine operation at the Whipple 10 m Telescope

  5. Electronic bulletin board system for image and information exchange

    International Nuclear Information System (INIS)

    Halama, J.R.; Henkin, R.E.; Wagner, R.H.

    1990-01-01

    This paper provides nuclear medicine professionals access to an electronic bulletin board (EBB) for image and information exchange. EBB users access the system remotely via modem and personal computer. A public message board is maintained containing messages posted by users. New messages or replies to existing messages may be posted. A public library board contains documents and images for users to access by transmitting them locally for off-line review. Comments and replies may be posted in the library board. New files may be posted in the library at any time. The EBB programs were developed on a multi-user computer system, allowing simultaneous access of users and on-line conferencing among active users

  6. Application of FPGA's in Flexible Analogue Electronic Image Generator Design

    Directory of Open Access Journals (Sweden)

    Peter Kulla

    2006-01-01

    Full Text Available This paper focuses on usage of the FPGAs (Field Programmable Gate Arrays Xilinx as a part of our more complex workdedicated to design of flexible analogue electronic images generator for application in TV measurement technique or/and TV servicetechnique or/and education process. The FPGAs performs here the role of component colour R, G, B, synchronization and blanking signals source. These signals are next processed and amplified in other parts of the generator as NTSC/PAL source encoder and RF modulator. The main aim of this paper is to show the possibilities how with suitable development software use a FPGAs in analog TV technology.

  7. Ultrafast molecular imaging by laser-induced electron diffraction

    International Nuclear Information System (INIS)

    Peters, M.; Nguyen-Dang, T. T.; Cornaggia, C.; Saugout, S.; Charron, E.; Keller, A.; Atabek, O.

    2011-01-01

    We address the feasibility of imaging geometric and orbital structures of a polyatomic molecule on an attosecond time scale using the laser-induced electron diffraction (LIED) technique. We present numerical results for the highest molecular orbitals of the CO 2 molecule excited by a near-infrared few-cycle laser pulse. The molecular geometry (bond lengths) is determined within 3% of accuracy from a diffraction pattern which also reflects the nodal properties of the initial molecular orbital. Robustness of the structure determination is discussed with respect to vibrational and rotational motions with a complete interpretation of the laser-induced mechanisms.

  8. A distortion correction method for image intensifier and electronic portal images used in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Ioannidis, G T; Geramani, K N; Zamboglou, N [Strahlenklinik, Stadtische Kliniken Offenbach, Offenbach (Germany); Uzunoglu, N [Department of Electrical and Computer Engineering, National Technical University of Athens, Athens (Greece)

    1999-12-31

    At the most of radiation departments a simulator and an `on line` verification system of the treated volume, in form of an electronic portal imaging device (EPID), are available. Networking and digital handling (saving, archiving etc.) of the image information is a necessity in the image processing procedures in order to evaluate verification and simulation recordings at the computer screen. Distortion is on the other hand prerequisite for quantitative comparison of both image modalities. Another limitation factor, in order to make quantitative assertions, is the fact that the irradiation fields in radiotherapy are usually bigger than the field of view of an image intensifier. Several segments of the irradiation field must therefore be acquired. Using pattern recognition techniques these segments can be composed into a single image. In this paper a distortion correction method will be presented. The method is based upon a well defined Grid which is embedded during the registration process on the image. The video signal from the image intensifier is acquired and processed. The grid is then recognised using image processing techniques. Ideally if all grid points are recognised, various methods can be applied in order to correct the distortion. But in practice this is not the case. Overlapping structures (bones etc.) have as a consequence that not all of the grid points can be recognised. Mathematical models from the Graph theory are applied in order to reconstruct the whole grid. The deviation of the grid points positions from the rated value is then used to calculate correction coefficients. This method (well defined grid, grid recognition, correction factors) can also be applied in verification images from the EPID or in other image modalities, and therefore a quantitative comparison in radiation treatment is possible. The distortion correction method and the application on simulator images will be presented. (authors)

  9. False colour backscatter electron images and their application during electron microprobe analysis of ores and host rocks

    International Nuclear Information System (INIS)

    Cousens, D.R.; French, D.H.; Ramsden, A.R.

    1989-01-01

    The limited contrast range of conventional black and white imaging does not enable full use to be made of the dynamic range of the video signal obtained from a scanning electron microscope or microprobe. The use of false colour substantially increases the information that can be derived from such images enabling relationships to be displayed that cannot be observed in black and white. This capability is now used extensively in combination with quantitative electron microprobe analysis as a research tool for ore characterization and host rocks studies related to minerals exploration in the CSIRO Div.sion of Exploration Geoscience. Thus the CAMEBAX scanning electron microprobe has been modified to allow digital images acquisition and software (IMAGE) developed which allows false colour backscatter electron (BSE) images to be obtained during the course of routine electron microprobe analysis. 1 fig

  10. An electron beam imaging system for quality assurance in IORT

    Science.gov (United States)

    Casali, F.; Rossi, M.; Morigi, M. P.; Brancaccio, R.; Paltrinieri, E.; Bettuzzi, M.; Romani, D.; Ciocca, M.; Tosi, G.; Ronsivalle, C.; Vignati, M.

    2004-01-01

    Intraoperative radiation therapy is a special radiotherapy technique, which enables a high dose of radiation to be given in a single fraction during oncological surgery. The major stumbling block to the large-scale application of the technique is the transfer of the patient, with an open wound, from the operating room to the radiation therapy bunker, with the consequent organisational problems and the increased risk of infection. To overcome these limitations, in the last few years a new kind of linear accelerator, the Novac 7, conceived for direct use in the surgical room, has become available. Novac 7 can deliver electron beams of different energies (3, 5, 7 and 9 MeV), with a high dose rate (up to 20 Gy/min). The aim of this work, funded by ENEA in the framework of a research contract, is the development of an innovative system for on-line measurements of 2D dose distributions and electron beam characterisation, before radiotherapy treatment with Novac 7. The system is made up of the following components: (a) an electron-light converter; (b) a 14 bit cooled CCD camera; (c) a personal computer with an ad hoc written software for image acquisition and processing. The performances of the prototype have been characterised experimentally with different electron-light converters. Several tests have concerned the assessment of the detector response as a function of impulse number and electron beam energy. Finally, the experimental results concerning beam profiles have been compared with data acquired with other dosimetric techniques. The achieved results make it possible to say that the developed system is suitable for fast quality assurance measurements and verification of 2D dose distributions.

  11. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Tobias, B., E-mail: bjtobias@pppl.gov [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Domier, C. W.; Luhmann, N. C.; Luo, C.; Mamidanna, M.; Phan, T.; Pham, A.-V.; Wang, Y. [University of California at Davis, Davis, California 95616 (United States)

    2016-11-15

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50–150 GHz) to an intermediate frequency (IF) band (e.g. 0.1–18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10× improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). Implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  12. An electronically tunable ultrafast laser source applied to fluorescence imaging and fluorescence lifetime imaging microscopy

    International Nuclear Information System (INIS)

    Dunsby, C; Lanigan, P M P; McGinty, J; Elson, D S; Requejo-Isidro, J; Munro, I; Galletly, N; McCann, F; Treanor, B; Oenfelt, B; Davis, D M; Neil, M A A; French, P M W

    2004-01-01

    Fluorescence imaging is used widely in microscopy and macroscopic imaging applications for fields ranging from biomedicine to materials science. A critical component for any fluorescence imaging system is the excitation source. Traditionally, wide-field systems use filtered thermal or arc-generated white light sources, while point scanning confocal microscope systems require spatially coherent (point-like) laser sources. Unfortunately, the limited range of visible wavelengths available from conventional laser sources constrains the design and usefulness of fluorescent probes in confocal microscopy. A 'hands-off' laser-like source, electronically tunable across the visible spectrum, would be invaluable for fluorescence imaging and provide new opportunities, e.g. automated excitation fingerprinting and in situ measurement of excitation cross-sections. Yet more information can be obtained using fluorescence lifetime imaging (FLIM), which requires that the light source be pulsed or rapidly modulated. We show how a white light continuum, generated by injecting femtosecond optical radiation into a micro-structured optical fibre, coupled with a simple prism-based tunable filter arrangement, can fulfil all these roles as a continuously electronically tunable (435-1150 nm) visible ultrafast light source in confocal, wide-field and FLIM systems

  13. Robust image alignment for cryogenic transmission electron microscopy.

    Science.gov (United States)

    McLeod, Robert A; Kowal, Julia; Ringler, Philippe; Stahlberg, Henning

    2017-03-01

    Cryo-electron microscopy recently experienced great improvements in structure resolution due to direct electron detectors with improved contrast and fast read-out leading to single electron counting. High frames rates enabled dose fractionation, where a long exposure is broken into a movie, permitting specimen drift to be registered and corrected. The typical approach for image registration, with high shot noise and low contrast, is multi-reference (MR) cross-correlation. Here we present the software package Zorro, which provides robust drift correction for dose fractionation by use of an intensity-normalized cross-correlation and logistic noise model to weight each cross-correlation in the MR model and filter each cross-correlation optimally. Frames are reliably registered by Zorro with low dose and defocus. Methods to evaluate performance are presented, by use of independently-evaluated even- and odd-frame stacks by trajectory comparison and Fourier ring correlation. Alignment of tiled sub-frames is also introduced, and demonstrated on an example dataset. Zorro source code is available at github.com/CINA/zorro. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Electron energy loss spectroscopy microanalysis and imaging in the transmission electron microscope: example of biological applications

    International Nuclear Information System (INIS)

    Diociaiuti, Marco

    2005-01-01

    This paper reports original results obtained in our laboratory over the past few years in the application of both electron energy loss spectroscopy (EELS) and electron spectroscopy imaging (ESI) to biological samples, performed in two transmission electron microscopes (TEM) equipped with high-resolution electron filters and spectrometers: a Gatan model 607 single magnetic sector double focusing EEL serial spectrometer attached to a Philips 430 TEM and a Zeiss EM902 Energy Filtering TEM. The primary interest was on the possibility offered by the combined application of these spectroscopic techniques with those offered by the TEM. In particular, the electron beam focusing available in a TEM allowed us to perform EELS and ESI on very small sample volumes, where high-resolution imaging and electron diffraction techniques can provide important structural information. I show that ESI was able to improve TEM performance, due to the reduced chromatic aberration and the possibility of avoiding the sample staining procedure. Finally, the analysis of the oscillating extended energy loss fine structure (EXELFS) beyond the ionization edges characterizing the EELS spectra allowed me, in a manner very similar to the extended X-ray absorption fine structure (EXAFS) analysis of the X-ray absorption spectra, to obtain short-range structural information for such light elements of biological interest as O or Fe. The Philips EM430 (250-300 keV) TEM was used to perform EELS microanalysis on Ca, P, O, Fe, Al and Si. The assessment of the detection limits of this method was obtained working with well-characterized samples containing Ca and P, and mimicking the actual cellular matrix. I applied EELS microanalysis to Ca detection in bone tissue during the mineralization process and to P detection in the cellular membrane of erythrocytes treated with an anti-tumoral drug, demonstrating that the cellular membrane is a drug target. I applied EELS microanalysis and selected area electron

  15. Imaging the square of the correlated two-electron wave function of a hydrogen molecule.

    Science.gov (United States)

    Waitz, M; Bello, R Y; Metz, D; Lower, J; Trinter, F; Schober, C; Keiling, M; Lenz, U; Pitzer, M; Mertens, K; Martins, M; Viefhaus, J; Klumpp, S; Weber, T; Schmidt, L Ph H; Williams, J B; Schöffler, M S; Serov, V V; Kheifets, A S; Argenti, L; Palacios, A; Martín, F; Jahnke, T; Dörner, R

    2017-12-22

    The toolbox for imaging molecules is well-equipped today. Some techniques visualize the geometrical structure, others the electron density or electron orbitals. Molecules are many-body systems for which the correlation between the constituents is decisive and the spatial and the momentum distribution of one electron depends on those of the other electrons and the nuclei. Such correlations have escaped direct observation by imaging techniques so far. Here, we implement an imaging scheme which visualizes correlations between electrons by coincident detection of the reaction fragments after high energy photofragmentation. With this technique, we examine the H 2 two-electron wave function in which electron-electron correlation beyond the mean-field level is prominent. We visualize the dependence of the wave function on the internuclear distance. High energy photoelectrons are shown to be a powerful tool for molecular imaging. Our study paves the way for future time resolved correlation imaging at FELs and laser based X-ray sources.

  16. Chemical Reactions of Molecules Promoted and Simultaneously Imaged by the Electron Beam in Transmission Electron Microscopy.

    Science.gov (United States)

    Skowron, Stephen T; Chamberlain, Thomas W; Biskupek, Johannes; Kaiser, Ute; Besley, Elena; Khlobystov, Andrei N

    2017-08-15

    The main objective of this Account is to assess the challenges of transmission electron microscopy (TEM) of molecules, based on over 15 years of our work in this field, and to outline the opportunities in studying chemical reactions under the electron beam (e-beam). During TEM imaging of an individual molecule adsorbed on an atomically thin substrate, such as graphene or a carbon nanotube, the e-beam transfers kinetic energy to atoms of the molecule, displacing them from equilibrium positions. Impact of the e-beam triggers bond dissociation and various chemical reactions which can be imaged concurrently with their activation by the e-beam and can be presented as stop-frame movies. This experimental approach, which we term ChemTEM, harnesses energy transferred from the e-beam to the molecule via direct interactions with the atomic nuclei, enabling accurate predictions of bond dissociation events and control of the type and rate of chemical reactions. Elemental composition and structure of the reactant molecules as well as the operating conditions of TEM (particularly the energy of the e-beam) determine the product formed in ChemTEM processes, while the e-beam dose rate controls the reaction rate. Because the e-beam of TEM acts simultaneously as a source of energy for the reaction and as an imaging tool monitoring the same reaction, ChemTEM reveals atomic-level chemical information, such as pathways of reactions imaged for individual molecules, step-by-step and in real time; structures of illusive reaction intermediates; and direct comparison of catalytic activity of different transition metals filmed with atomic resolution. Chemical transformations in ChemTEM often lead to previously unforeseen products, demonstrating the potential of this method to become not only an analytical tool for studying reactions, but also a powerful instrument for discovery of materials that can be synthesized on preparative scale.

  17. Secondary electron images obtained with a standard photoelectron emission microscope set-up

    International Nuclear Information System (INIS)

    Benka, Oswald; Zeppenfeld, Peter

    2005-01-01

    The first results of secondary electron images excited by 3-4.3 keV electrons are presented. The images are obtained with a standard FOCUS-PEEM set-up equipped with an imaging energy filter (IEF). The electron gun was mounted on a standard PEEM entrance flange at an angle of 25 deg. with respect to the sample surface. A low extraction voltage of 500 V was used to minimize the deflection of the electron beam by the PEEM extraction electrode. The secondary electron images are compared to photoelectron images excited by a standard 4.9 eV UV lamp. In the case of a Cu pattern on a Si substrate it is found that the lateral resolution without the IEF is about the same for electron and photon excitation but that the relative electron emission intensities are very different. The use of the IEF reduces the lateral resolution. Images for secondary electron energies between eV 1 and eV 2 were obtained by setting the IEF to -V 1 and -V 2 ∼-(V 1 +5V) potentials and taking the difference of both images. Images up to 100 eV electron energies were recorded. The material contrast obtained in these difference images is discussed in terms of a secondary electron and photoelectron emission model and secondary electron energy spectra measured with a LEED-Auger spectrometer

  18. Advances in imaging and electron physics optics of charged particle analyzers

    CERN Document Server

    Hawkes, Peter W

    2011-01-01

    Advances in Imaging and Electron Physics merges two long-running serials--Advances in Electronics and Electron Physics and Advances in Optical and Electron Microscopy. This series features extended articles on the physics of electron devices (especially semiconductor devices), particle optics at high and low energies, microlithography, image science and digital image processing, electromagnetic wave propagation, electron microscopy, and the computing methods used in all these domains. Contributions from leading international scholars and industry experts Discusses hot topic areas and presents current and future research trends Invaluable reference and guide for physicists, engineers and mathematicians.

  19. Advances in imaging and electron physics optics of charged particle analyzers

    CERN Document Server

    Hawkes, Peter W

    2011-01-01

    Advances in Imaging and Electron Physics merges two long-running serials--Advances in Electronics and Electron Physics and Advances in Optical and Electron Microscopy. This series features extended articles on the physics of electron devices (especially semiconductor devices), particle optics at high and low energies, microlithography, image science and digital image processing, electromagnetic wave propagation, electron microscopy, and the computing methods used in all these domains. * Contributions from leading international scholars and industry experts * Discusses hot topic areas and presents current and future research trends * Invaluable reference and guide for physicists, engineers and mathematicians.

  20. NOTE: A method for controlling image acquisition in electronic portal imaging devices

    Science.gov (United States)

    Glendinning, A. G.; Hunt, S. G.; Bonnett, D. E.

    2001-02-01

    Certain types of camera-based electronic portal imaging devices (EPIDs) which initiate image acquisition based on sensing a change in video level have been observed to trigger unreliably at the beginning of dynamic multileaf collimation sequences. A simple, novel means of controlling image acquisition with an Elekta linear accelerator (Elekta Oncology Systems, Crawley, UK) is proposed which is based on illumination of a photodetector (ORP-12, Silonex Inc., Plattsburgh, NY, USA) by the electron gun of the accelerator. By incorporating a simple trigger circuit it is possible to derive a beam on/off status signal which changes at least 100 ms before any dose is measured by the accelerator. The status signal does not return to the beam-off state until all dose has been delivered and is suitable for accelerator pulse repetition frequencies of 50-400 Hz. The status signal is thus a reliable means of indicating the initiation and termination of radiation exposure, and thus controlling image acquisition of such EPIDs for this application.

  1. Current profile reconstruction using electron temperature imaging diagnostics

    International Nuclear Information System (INIS)

    Tritz, K.; Stutman, D.; Delgado-Aparicio, L.F.; Finkenthal, M.; Pacella, D.; Kaita, R.; Stratton, B.; Sabbagh, S.

    2004-01-01

    Flux surface shape information can be used to constrain the current profile for reconstruction of the plasma equilibrium. One method of inferring flux surface shape relies on plasma x-ray emission; however, deviations from the flux surfaces due to impurity and density asymmetries complicate the interpretation. Electron isotherm surfaces should correspond well to the plasma flux surfaces, and equilibrium constraint modeling using this isotherm information constrains the current profile. The KFIT code is used to assess the profile uncertainty and to optimize the number, location and SNR required for the Te detectors. As Te imaging detectors we consider tangentially viewing, vertically spaced, linear gas electron multiplier arrays operated in pulse height analysis (PHA) mode and multifoil soft x-ray arrays. Isoflux coordinate sets provided by T e measurements offer a strong constraint on the equilibrium reconstruction in both a stacked horizontal array configuration and a crossed horizontal and vertical beam system, with q 0 determined to within ±4%. The required SNR can be provided with either PHA or multicolor diagnostic techniques, though the multicolor system requires ∼x4 better statistics for comparable final errors

  2. Imaging photoelectron photoion coincidence spectroscopy with velocity focusing electron optics

    International Nuclear Information System (INIS)

    Bodi, Andras; Johnson, Melanie; Gerber, Thomas; Gengeliczki, Zsolt; Sztaray, Balint; Baer, Tomas

    2009-01-01

    An imaging photoelectron photoion coincidence spectrometer at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source is presented and a few initial measurements are reported. Monochromatic synchrotron VUV radiation ionizes the cooled or thermal gas-phase sample. Photoelectrons are velocity focused, with better than 1 meV resolution for threshold electrons, and also act as start signal for the ion time-of-flight analysis. The ions are accelerated in a relatively low, 40-80 V cm -1 field, which enables the direct measurement of rate constants in the 10 3 -10 7 s -1 range. All electron and ion events are recorded in a triggerless multiple-start/multiple-stop setup, which makes it possible to carry out coincidence experiments at >100 kHz event frequencies. As examples, the threshold photoelectron spectrum of the argon dimer and the breakdown diagrams for hydrogen atom loss in room temperature methane and the chlorine atom loss in cold chlorobenzene are shown and discussed.

  3. Analysis and modeling of electronic portal imaging exit dose measurements

    International Nuclear Information System (INIS)

    Pistorius, S.; Yeboah, C.

    1995-01-01

    In spite of the technical advances in treatment planning and delivery in recent years, it is still unclear whether the recommended accuracy in dose delivery is being achieved. Electronic portal imaging devices, now in routine use in many centres, have the potential for quantitative dosimetry. As part of a project which aims to develop an expert-system based On-line Dosimetric Verification (ODV) system we have investigated and modelled the dose deposited in the detector of a video based portal imaging system. Monte Carlo techniques were used to simulate gamma and x-ray beams in homogeneous slab phantom geometries. Exit doses and energy spectra were scored as a function of (i) slab thickness, (ii) field size and (iii) the air gap between the exit surface and the detector. The results confirm that in order to accurately calculate the dose in the high atomic number Gd 2 O 2 S detector for a range of air gaps, field sizes and slab thicknesses both the magnitude of the primary and scattered components and their effective energy need to be considered. An analytic, convolution based model which attempts to do this is proposed. The results of the simulation and the ability of the model to represent these data will be presented and discussed. This model is used to show that, after training, a back-propagation feed-forward cascade correlation neural network has the ability to identify and recognise the cause of, significant dosimetric errors

  4. Professional Acceptance Of Electronic Images In Radiologic Practice

    Science.gov (United States)

    Gitlin, Joseph N.; Curtis, David J.; Kerlin, Barbara D.; Olmsted, William W.

    1983-05-01

    During the past four years, a large number of radiographic images have been interpreted in both film and video modes in an effort to determine the utility of digital/analogue systems in general practice. With the cooperation of the Department of Defense, the MITRE Corporation, and several university-based radiology departments, the Public Health Service has participated in laboratory experiments and a teleradiology field trial to meet this objective. During the field trial, 30 radiologists participated in the interpretation of more than 4,000 diagnostic x-ray examinations that were performed at distant clinics, digitized, and transmitted to a medical center for interpretation on video monitors. As part of the evaluation, all of the participating radiologists and the attending physicians at the clinics were queried regarding the teleradiology system, particularly with respect to the diagnostic quality of the electronic images. The original films for each of the 4,000 examinations were read independently, and the findings and impressions from each mode were compared to identify discrepancies. In addition, a sample of 530 cases was reviewed and interpreted by a consensus panel to measure the accuracy of findings and impressions of both film and video readings. The sample has been retained in an automated archive for future study at the National Center of Devices and Radiological Health facilities in Rockville, Maryland. The studies include a comparison of diagnostic findings and impressions from 1024 x 1024 matrices with those obtained from the 512 x 512 format used in the field trial. The archive also provides a database for determining the effect of data compression techniques on diagnostic interpretations and establishing the utility of image processing algorithms. The paper will include an analysis of the final results of the field trial and preliminary findings from the ongoing studies using the archive of cases at the National Center for Devices and Radiological

  5. Free radicals imaged in vivo in the rat by using proton-electron double-resonance imaging

    International Nuclear Information System (INIS)

    Lurie, D.J.; Nicholson, Ian; Foster, M.A.; Mallard, J.R.

    1990-01-01

    A new technique called proton-electron double-resonance imaging is described for imaging free radicals in aqueous samples. The method is a combination of proton NMR imaging with nuclear electron double resonance. The results of using this technique to image free radicals in vivo in the rat are presented. Rats were injected intravenously with a nitroxide free radical solution and a series of images was obtained from which the clearance of the free radical through the liver and kidneys could be observed. (author)

  6. Computer experiments on the imaging of point defects with the conventional transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Krakow, W [Xerox Corp., Rochester, N.Y. (USA)

    1978-02-01

    To aid in the interpretation of high resolution electron micrographs of defect structures in crystals, computer-simulated dark-field electron micrographs have been obtained for a variety of point defects in metals. Interpretation of these images in terms of atomic positions and atom correlations becomes straightforward, and it is a simple matter to distinguish between real structural information and image artifacts produced by the phase contrast mechanism in the electron optical imaging process.

  7. Electron dose dependence of signal-to-noise ratio, atom contrast and resolution in transmission electron microscope images

    International Nuclear Information System (INIS)

    Lee, Z.; Rose, H.; Lehtinen, O.; Biskupek, J.; Kaiser, U.

    2014-01-01

    In order to achieve the highest resolution in aberration-corrected (AC) high-resolution transmission electron microscopy (HRTEM) images, high electron doses are required which only a few samples can withstand. In this paper we perform dose-dependent AC-HRTEM image calculations, and study the dependence of the signal-to-noise ratio, atom contrast and resolution on electron dose and sampling. We introduce dose-dependent contrast, which can be used to evaluate the visibility of objects under different dose conditions. Based on our calculations, we determine optimum samplings for high and low electron dose imaging conditions. - Highlights: • The definition of dose-dependent atom contrast is introduced. • The dependence of the signal-to-noise ratio, atom contrast and specimen resolution on electron dose and sampling is explored. • The optimum sampling can be determined according to different dose conditions

  8. The E4 protein; structure, function and patterns of expression

    Energy Technology Data Exchange (ETDEWEB)

    Doorbar, John, E-mail: jdoorba@nimr.mrc.ac.uk

    2013-10-15

    The papillomavirus E4 open reading frame (ORF) is contained within the E2 ORF, with the primary E4 gene-product (E1{sup ∧}E4) being translated from a spliced mRNA that includes the E1 initiation codon and adjacent sequences. E4 is located centrally within the E2 gene, in a region that encodes the E2 protein′s flexible hinge domain. Although a number of minor E4 transcripts have been reported, it is the product of the abundant E1{sup ∧}E4 mRNA that has been most extensively analysed. During the papillomavirus life cycle, the E1{sup ∧}E4 gene products generally become detectable at the onset of vegetative viral genome amplification as the late stages of infection begin. E4 contributes to genome amplification success and virus synthesis, with its high level of expression suggesting additional roles in virus release and/or transmission. In general, E4 is easily visualised in biopsy material by immunostaining, and can be detected in lesions caused by diverse papillomavirus types, including those of dogs, rabbits and cattle as well as humans. The E4 protein can serve as a biomarker of active virus infection, and in the case of high-risk human types also disease severity. In some cutaneous lesions, E4 can be expressed at higher levels than the virion coat proteins, and can account for as much as 30% of total lesional protein content. The E4 proteins of the Beta, Gamma and Mu HPV types assemble into distinctive cytoplasmic, and sometimes nuclear, inclusion granules. In general, the E4 proteins are expressed before L2 and L1, with their structure and function being modified, first by kinases as the infected cell progresses through the S and G2 cell cycle phases, but also by proteases as the cell exits the cell cycle and undergoes true terminal differentiation. The kinases that regulate E4 also affect other viral proteins simultaneously, and include protein kinase A, Cyclin-dependent kinase, members of the MAP Kinase family and protein kinase C. For HPV16 E1{sup ∧}E

  9. Electron spectroscopic imaging of antigens by reaction with boronated antibodies.

    Science.gov (United States)

    Qualmann, B; Kessels, M M; Klobasa, F; Jungblut, P W; Sierralta, W D

    1996-07-01

    Two small homogeneous markers for electron spectroscopic imaging (ESI) containing eight dodecaborane cages linked to a poly-alpha, epsilon-L-lysine dendrimer were synthesized; one of these was made water soluble by the attachment of a polyether. The markers were coupled to the sulfhydryl group of (monovalent) antibody fragments (Fab') by a homobifunctional cross-linker. While the coupling ratios of the poorly water-soluble compound did not exceed 20%, the polyether-containing variant reacted quantitatively. Its suitability for immunolabelling was tested in a study of the mechanism of the transcellular transport of an administered heterologous protein (bovine serum albumin, BSA) through ileal enterocytes of newborn piglets by endocytotic vesicles in comparison to conventional immunogold reagents. The post-embedding technique was employed. The boronated Fab' gave rise to considerably higher tagging frequencies than seen with immunogold, as could be expected from its form- and size-related physical advantages and the dense packing of BSA in the vesicles. The new probe, carrying the antigen-combining cleft at one end and the boron clusters at the opposite end of the oval-shaped conjugate, add to the potential of ESI-based immunocytochemistry.

  10. Imaging of osteo-odonto-keratoprosthesis by electron beam tomography.

    Science.gov (United States)

    Fong, K C S; Ferrett, C G; Tandon, R; Paul, B; Herold, J; Liu, C S C

    2005-08-01

    To describe the experience of using electron beam tomography (EBT) in imaging of osteo-odonto-keratoprosthesis (OOKP) to identify early bone and dentine loss which may threaten the viability of the eye. Seven patients with an OOKP in one eye underwent EBT. The OOKP lamina dimensions were measured on EBT and compared to the manual measurements at the time of surgery. There was a high degree of resolution of the OOKP lamina noted with EBT. In particular, it identified three patients with a marked degree of thinning of the lamina edges. Two of these patients had OOKP that were allografts. The mean time from surgery to examination was 3.6 years (range 1.2-5 years) while the mean age of the patients was 56 years (range 31-79 years). It is important to monitor regularly the dimensions and stability of the OOKP lamina as it will help detect cases that are at risk of extrusion of the optical cylinder and consequent endophthalmitis. Prophylactic measures can then be taken to prevent such serious complications from occurring. In this series, the authors found EBT to have excellent resolution and speed and they would support regular scanning of the OOKP lamina in all patients.

  11. The influence of structure depth on image blurring of micrometres-thick specimens in MeV transmission electron imaging.

    Science.gov (United States)

    Wang, Fang; Sun, Ying; Cao, Meng; Nishi, Ryuji

    2016-04-01

    This study investigates the influence of structure depth on image blurring of micrometres-thick films by experiment and simulation with a conventional transmission electron microscope (TEM). First, ultra-high-voltage electron microscope (ultra-HVEM) images of nanometer gold particles embedded in thick epoxy-resin films were acquired in the experiment and compared with simulated images. Then, variations of image blurring of gold particles at different depths were evaluated by calculating the particle diameter. The results showed that with a decrease in depth, image blurring increased. This depth-related property was more apparent for thicker specimens. Fortunately, larger particle depth involves less image blurring, even for a 10-μm-thick epoxy-resin film. The quality dependence on depth of a 3D reconstruction of particle structures in thick specimens was revealed by electron tomography. The evolution of image blurring with structure depth is determined mainly by multiple elastic scattering effects. Thick specimens of heavier materials produced more blurring due to a larger lateral spread of electrons after scattering from the structure. Nevertheless, increasing electron energy to 2MeV can reduce blurring and produce an acceptable image quality for thick specimens in the TEM. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. 77 FR 31875 - Certain Electronic Imaging Devices; Notice of Receipt of Complaint; Solicitation of Comments...

    Science.gov (United States)

    2012-05-30

    ... INTERNATIONAL TRADE COMMISSION [Docket No. 2898] Certain Electronic Imaging Devices; Notice of... Trade Commission. ACTION: Notice. SUMMARY: Notice is hereby given that the U.S. International Trade Commission has received a complaint entitled Certain Electronic Imaging Devices, DN 2898; the Commission is...

  13. 77 FR 32995 - Certain Electronic Imaging Devices Corrected: Notice of Receipt of Complaint; Solicitation of...

    Science.gov (United States)

    2012-06-04

    ... INTERNATIONAL TRADE COMMISSION [Docket No. 2898] Certain Electronic Imaging Devices Corrected.... International Trade Commission. ACTION: Notice. SUMMARY: Notice is hereby given that the U.S. International Trade Commission has received a complaint entitled Certain Electronic Imaging Devices, DN 2898; the...

  14. Athermal electron distribution probed by femtosecond multiphoton photoemission from image potential states

    International Nuclear Information System (INIS)

    Ferrini, Gabriele; Giannetti, Claudio; Pagliara, Stefania; Banfi, Francesco; Galimberti, Gianluca; Parmigiani, Fulvio

    2005-01-01

    Image potential states are populated through indirect, scattering-mediated multiphoton absorption induced by femtosecond laser pulses and revealed by single-photon photoemission. The measured effective mass is significantly different from that obtained with direct, resonant population. These features reveal a strong coupling of the electrons residing in the image potential state, outside the solid, with the underlying hot electron population created by the laser pulse. The coupling is mediated by a many-body scattering interaction between the image potential state electrons and bulk electrons in highly excited states

  15. Evaluation of image quality for various electronic portal imaging devices in radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Son, Soon Yong; Choi, Kwan Woo [Dept. of Radiology, Asan Medical Center, Seoul (Korea, Republic of); Kim, Jung Min [Dept. of College of Health Science, Radiologic Science, Korea University, Seoul (Korea, Republic of); and others

    2015-12-15

    In megavoltage (MV) radiotherapy, delivering the dose to the target volume is important while protecting the surrounding normal tissue. The purpose of this study was to evaluate the modulation transfer function (MTF), the noise power spectrum (NPS), and the detective quantum efficiency (DQE) using an edge block in megavoltage X-ray imaging (MVI). We used an edge block, which consists of tungsten with dimensions of 19 (thickness) × 10 (length) × 1 (width) cm3 and measured the pre-sampling MTF at 6 MV energy. Various radiation therapy (RT) devices such as TrueBeamTM (Varian), BEAMVIEWPLUS (Siemens), iViewGT (Elekta) and Clinac®iX (Varian) were used. As for MTF results, TrueBeamTM(Varian) flattening filter free(FFF) showed the highest values of 0.46 mm-1and1.40mm-1for MTF 0.5 and 0.1. In NPS, iViewGT (Elekta) showed the lowest noise distribution. In DQE, iViewGT (Elekta) showed the best efficiency at a peak DQE and 1 mm-1DQE of 0.0026 and 0.00014, respectively. This study could be used not only for traditional QA imaging but also for quantitative MTF, NPS, and DQE measurement for development of an electronic portal imaging device (EPID)

  16. Bianchi congruences of two-dimensional surfaces in E4

    International Nuclear Information System (INIS)

    Gor'kavyi, V A

    2005-01-01

    Pseudospherical Bianchi congruences in Euclidean 4-space E 4 are considered. The focal surfaces of such congruences are shown to have a constant negative Gaussian curvature. A geometric and an analytic description of special pseudo- spherical surfaces in E 4 admitting a Bianchi congruence are obtained.

  17. Evaluation of usefulness of portal image using Electronic Portal Imaging Device (EPID) in the patients who received pelvic radiation therapy

    International Nuclear Information System (INIS)

    Kim, Woo Chul; Kim, Heon Jong; Park, Seong Young; Cho, Young Kap; Loh, John J. K.; Park, Won; Suh, Chang Ok; Kim, Gwi Eon

    1998-01-01

    To evaluate the usefulness of electronic portal imaging device through objective compare of the images acquired using an EPID and a conventional port film. From Apr. to Oct. 1997, a total of 150 sets of images from 20 patients who received radiation therapy in the pelvis area were evaluated in the Inha University Hospital and Severance Hospital. A dual image recording technique was devised to obtain both electronic portal images and port film images simultaneously with one treatment course. We did not perform double exposure. Five to ten images were acquired from each patient. All images were acquired from posteroanterior (PA) view except images from two patients. A dose rate of 100-300 MU/min and a 10-MV X-ray beam were used and 2-10 MUs were required to produce a verification image during treatment. Kodak diagnostic film with metal/film imaging cassette which was located on the top of the EPID detector was used for the port film. The source to detector distance was 140 cm. Eight anatomical landmarks (pelvic brim, sacrum, acetabulum, iliopectineal line, symphysis, ischium, obturator foramen, sacroiliac joint) were assessed. Four radiation oncologist joined to evaluate each image. The individual landmarks in the port film or in the EPID were rated-very clear (1), clear (2), visible (3), notclear (4), not visible (5). Using an video camera based EPID system, there was no difference of image quality between no enhanced EPID images and port film images. However, when we provided some change with window level for the portal image, the visibility of the sacrum and obturator foramen was improved in the portal images than in the port film images. All anatomical landmarks were more visible in the portal images than in the port film when we applied the CLAHE mode enhancement. The images acquired using an matrix ion chamber type EPID were also improved image quality after window level adjustment. The quality of image acquired using an electronic portal imaging device was

  18. About the information depth of backscattered electron imaging

    Czech Academy of Sciences Publication Activity Database

    Piňos, Jakub; Mikmeková, Šárka; Frank, Luděk

    2017-01-01

    Roč. 266, č. 3 (2017), s. 335-342 ISSN 0022-2720 Institutional support: RVO:68081731 Keywords : backscattered electrons * information depth * penetration of electrons Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Materials engineering Impact factor: 1.692, year: 2016

  19. Features of atomic images reconstructed from photoelectron, Auger electron, and internal detector electron holography using SPEA-MEM

    Energy Technology Data Exchange (ETDEWEB)

    Matsushita, Tomohiro, E-mail: matusita@spring8.or.jp [Japan Synchrotron Radiation Research Institute, SPring-8, Sayo, Hyogo 679-5198 (Japan); Matsui, Fumihiko [Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192 (Japan)

    2014-08-15

    Highlights: • We develop a 3D atomic image reconstruction algorithm for photoelectron, Auger electron, and internal detector holography. • We examine the shapes of the atomic images reconstructed by using a developed kernel function. • We examine refraction effect at surface, limitation effect of the hologram data, energy resolution effect, and angular resolution effect. • These discussions indicate the experimental requirements to obtain the clear 3D atomic image. - Abstract: Three-dimensional atomic images can be reconstructed from photoelectron, Auger electron, and internal detector electron holograms using a scattering pattern extraction algorithm using the maximum entropy method (SPEA-MEM) that utilizes an integral transform. An integral kernel function for the integral transform is the key to clear atomic image reconstruction. We composed the kernel function using a scattering pattern function and estimated its ability. Image distortion caused by multiple scattering was also evaluated. Four types of Auger electron wave functions were investigated, and the effect of these wave function types was estimated. In addition, we addressed refraction at the surface, the effects of data limitation, and energy and angular resolutions.

  20. Electronic noise in CT detectors: Impact on image noise and artifacts.

    Science.gov (United States)

    Duan, Xinhui; Wang, Jia; Leng, Shuai; Schmidt, Bernhard; Allmendinger, Thomas; Grant, Katharine; Flohr, Thomas; McCollough, Cynthia H

    2013-10-01

    The objective of our study was to evaluate in phantoms the differences in CT image noise and artifact level between two types of commercial CT detectors: one with distributed electronics (conventional) and one with integrated electronics intended to decrease system electronic noise. Cylindric water phantoms of 20, 30, and 40 cm in diameter were scanned using two CT scanners, one equipped with integrated detector electronics and one with distributed detector electronics. All other scanning parameters were identical. Scans were acquired at four tube potentials and 10 tube currents. Semianthropomorphic phantoms were scanned to mimic the shoulder and abdominal regions. Images of two patients were also selected to show the clinical values of the integrated detector. Reduction of image noise with the integrated detector depended on phantom size, tube potential, and tube current. Scans that had low detected signal had the greatest reductions in noise, up to 40% for a 30-cm phantom scanned using 80 kV. This noise reduction translated into up to 50% in dose reduction to achieve equivalent image noise. Streak artifacts through regions of high attenuation were reduced by up to 45% on scans obtained using the integrated detector. Patient images also showed superior image quality for the integrated detector. For the same applied radiation level, the use of integrated electronics in a CT detector showed a substantially reduced level of electronic noise, resulting in reductions in image noise and artifacts, compared with detectors having distributed electronics.

  1. A method of combining STEM image with parallel beam diffraction and electron-optical conditions for diffractive imaging

    International Nuclear Information System (INIS)

    He Haifeng; Nelson, Chris

    2007-01-01

    We describe a method of combining STEM imaging functionalities with nanoarea parallel beam electron diffraction on a modern TEM. This facilitates the search for individual particles whose diffraction patterns are needed for diffractive imaging or structural studies of nanoparticles. This also lays out a base for 3D diffraction data collection

  2. An improved image alignment procedure for high-resolution transmission electron microscopy.

    Science.gov (United States)

    Lin, Fang; Liu, Yan; Zhong, Xiaoyan; Chen, Jianghua

    2010-06-01

    Image alignment is essential for image processing methods such as through-focus exit-wavefunction reconstruction and image averaging in high-resolution transmission electron microscopy. Relative image displacements exist in any experimentally recorded image series due to the specimen drifts and image shifts, hence image alignment for correcting the image displacements has to be done prior to any further image processing. The image displacement between two successive images is determined by the correlation function of the two relatively shifted images. Here it is shown that more accurate image alignment can be achieved by using an appropriate aperture to filter the high-frequency components of the images being aligned, especially for a crystalline specimen with little non-periodic information. For the image series of crystalline specimens with little amorphous, the radius of the filter aperture should be as small as possible, so long as it covers the innermost lattice reflections. Testing with an experimental through-focus series of Si[110] images, the accuracies of image alignment with different correlation functions are compared with respect to the error functions in through-focus exit-wavefunction reconstruction based on the maximum-likelihood method. Testing with image averaging over noisy experimental images from graphene and carbon-nanotube samples, clear and sharp crystal lattice fringes are recovered after applying optimal image alignment. Copyright 2010 Elsevier Ltd. All rights reserved.

  3. Inter- and Intrarater Reliability Using Different Software Versions of E4D Compare in Dental Education.

    Science.gov (United States)

    Callan, Richard S; Cooper, Jeril R; Young, Nancy B; Mollica, Anthony G; Furness, Alan R; Looney, Stephen W

    2015-06-01

    The problems associated with intra- and interexaminer reliability when assessing preclinical performance continue to hinder dental educators' ability to provide accurate and meaningful feedback to students. Many studies have been conducted to evaluate the validity of utilizing various technologies to assist educators in achieving that goal. The purpose of this study was to compare two different versions of E4D Compare software to determine if either could be expected to deliver consistent and reliable comparative results, independent of the individual utilizing the technology. Five faculty members obtained E4D digital images of students' attempts (sample model) at ideal gold crown preparations for tooth #30 performed on typodont teeth. These images were compared to an ideal (master model) preparation utilizing two versions of E4D Compare software. The percent correlations between and within these faculty members were recorded and averaged. The intraclass correlation coefficient was used to measure both inter- and intrarater agreement among the examiners. The study found that using the older version of E4D Compare did not result in acceptable intra- or interrater agreement among the examiners. However, the newer version of E4D Compare, when combined with the Nevo scanner, resulted in a remarkable degree of agreement both between and within the examiners. These results suggest that consistent and reliable results can be expected when utilizing this technology under the protocol described in this study.

  4. From Relativistic Electrons to X-ray Phase Contrast Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A. H. [Fermilab; Garson, A. B. [Washington U., St. Louis; Anastasio, M. A. [Washington U., St. Louis

    2017-10-09

    We report the initial demonstrations of the use of single crystals in indirect x-ray imaging for x-ray phase contrast imaging at the Washington University in St. Louis Computational Bioimaging Laboratory (CBL). Based on single Gaussian peak fits to the x-ray images, we observed a four times smaller system point spread function (21 μm (FWHM)) with the 25-mm diameter single crystals than the reference polycrystalline phosphor’s 80-μm value. Potential fiber-optic plate depth-of-focus aspects and 33-μm diameter carbon fiber imaging are also addressed.

  5. Apolipoprotein e4 allele and cognitive decline in elderly men

    NARCIS (Netherlands)

    Feskens, E.J.M.; Havekes, L.M.; Kalmijn, S.; Knijff, P. de; Launer, L.J.; Kromhout, D.

    1994-01-01

    Objectives - To determine whether polymorphism of apolipoprotein E - notably, the e4 allele - predicts cognitive deterioration in the general population. Design - Population based cohort investigated in 1990 and in 1993. Setting - Zutphen, the Netherlands. Subjects - Representative cohort of 538

  6. Making the transition to ANSI/ASQC E4

    International Nuclear Information System (INIS)

    Wolfe, D.W.

    1992-07-01

    As ANSI/ASQC E4, Quality Systems Requirements for Environmental Programs, nears final form and formal issuance by the American National Standards Institute (ANSI) and the American Society for Quality Control (ASQC), numerous organizations will be developing and implementing quality assurance programs based on the criteria promulgated by ANSI/ASQC E4. The organizations to initially adopt ANSI/ASQC E4 will be those that already have quality assurance programs based either on ASME NQA -1 or EPA QAMS-005/8. This paper presents the changes/enhancements required to transition an ASME NQA -1 or EPA QAMS-005/80 based quality assurance program to a program which meets the requirements of ANSI/ASQC E4

  7. Cost minimisation analysis: kilovoltage imaging with automated repositioning versus electronic portal imaging in image-guided radiotherapy for prostate cancer.

    Science.gov (United States)

    Gill, S; Younie, S; Rolfo, A; Thomas, J; Siva, S; Fox, C; Kron, T; Phillips, D; Tai, K H; Foroudi, F

    2012-10-01

    To compare the treatment time and cost of prostate cancer fiducial marker image-guided radiotherapy (IGRT) using orthogonal kilovoltage imaging (KVI) and automated couch shifts and orthogonal electronic portal imaging (EPI) and manual couch shifts. IGRT treatment delivery times were recorded automatically on either unit. Costing was calculated from real costs derived from the implementation of a new radiotherapy centre. To derive cost per minute for EPI and KVI units the total annual setting up and running costs were divided by the total annual working time. The cost per IGRT fraction was calculated by multiplying the cost per minute by the duration of treatment. A sensitivity analysis was conducted to test the robustness of our analysis. Treatment times without couch shift were compared. Time data were analysed for 8648 fractions, 6057 from KVI treatment and 2591 from EPI treatment from a total of 294 patients. The median time for KVI treatment was 6.0 min (interquartile range 5.1-7.4 min) and for EPI treatment it was 10.0 min (interquartile range 8.3-11.8 min) (P value time for EPI was 8.8 min and for KVI was 5.1 min. Treatment time is less on KVI units compared with EPI units. This is probably due to automation of couch shift and faster evaluation of imaging on KVI units. Annual running costs greatly outweigh initial setting up costs and therefore the cost per fraction was less with KVI, despite higher initial costs. The selection of appropriate IGRT equipment can make IGRT practical within radiotherapy departments. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  8. Prototype system for proton beam range measurement based on gamma electron vertex imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Han Rim [Neutron Utilization Technology Division, Korea Atomic Energy Research Institute, 111, Daedeok-daero 989beon-gil, Yuseong-gu, Daejeon 34057 (Korea, Republic of); Kim, Sung Hun; Park, Jong Hoon [Department of Nuclear Engineering, Hanyang University, Seongdong-gu, Seoul 04763 (Korea, Republic of); Jung, Won Gyun [Heavy-ion Clinical Research Division, Korean Institute of Radiological & Medical Sciences, Seoul 01812 (Korea, Republic of); Lim, Hansang [Department of Electronics Convergence Engineering, Kwangwoon University, Seoul 01897 (Korea, Republic of); Kim, Chan Hyeong, E-mail: chkim@hanyang.ac.kr [Department of Nuclear Engineering, Hanyang University, Seongdong-gu, Seoul 04763 (Korea, Republic of)

    2017-06-11

    In proton therapy, for both therapeutic effectiveness and patient safety, it is very important to accurately measure the proton dose distribution, especially the range of the proton beam. For this purpose, recently we proposed a new imaging method named gamma electron vertex imaging (GEVI), in which the prompt gammas emitting from the nuclear reactions of the proton beam in the patient are converted to electrons, and then the converted electrons are tracked to determine the vertices of the prompt gammas, thereby producing a 2D image of the vertices. In the present study, we developed a prototype GEVI system, including dedicated signal processing and data acquisition systems, which consists of a beryllium plate (= electron converter) to convert the prompt gammas to electrons, two double-sided silicon strip detectors (= hodoscopes) to determine the trajectories of those converted electrons, and a plastic scintillation detector (= calorimeter) to measure their kinetic energies. The system uses triple coincidence logic and multiple energy windows to select only the events from prompt gammas. The detectors of the prototype GEVI system were evaluated for electronic noise level, energy resolution, and time resolution. Finally, the imaging capability of the GEVI system was tested by imaging a {sup 90}Sr beta source, a {sup 60}Co gamma source, and a 45-MeV proton beam in a PMMA phantom. The overall results of the present study generally show that the prototype GEVI system can image the vertices of the prompt gammas produced by the proton nuclear interactions.

  9. General filtering method for electronic speckle pattern interferometry fringe images with various densities based on variational image decomposition.

    Science.gov (United States)

    Li, Biyuan; Tang, Chen; Gao, Guannan; Chen, Mingming; Tang, Shuwei; Lei, Zhenkun

    2017-06-01

    Filtering off speckle noise from a fringe image is one of the key tasks in electronic speckle pattern interferometry (ESPI). In general, ESPI fringe images can be divided into three categories: low-density fringe images, high-density fringe images, and variable-density fringe images. In this paper, we first present a general filtering method based on variational image decomposition that can filter speckle noise for ESPI fringe images with various densities. In our method, a variable-density ESPI fringe image is decomposed into low-density fringes, high-density fringes, and noise. A low-density fringe image is decomposed into low-density fringes and noise. A high-density fringe image is decomposed into high-density fringes and noise. We give some suitable function spaces to describe low-density fringes, high-density fringes, and noise, respectively. Then we construct several models and numerical algorithms for ESPI fringe images with various densities. And we investigate the performance of these models via our extensive experiments. Finally, we compare our proposed models with the windowed Fourier transform method and coherence enhancing diffusion partial differential equation filter. These two methods may be the most effective filtering methods at present. Furthermore, we use the proposed method to filter a collection of the experimentally obtained ESPI fringe images with poor quality. The experimental results demonstrate the performance of our proposed method.

  10. Design of a cathodoluminescence image generator using a Raspberry Pi coupled to a scanning electron microscope

    Science.gov (United States)

    Benítez, Alfredo; Santiago, Ulises; Sanchez, John E.; Ponce, Arturo

    2018-01-01

    In this work, an innovative cathodoluminescence (CL) system is coupled to a scanning electron microscope and synchronized with a Raspberry Pi computer integrated with an innovative processing signal. The post-processing signal is based on a Python algorithm that correlates the CL and secondary electron (SE) images with a precise dwell time correction. For CL imaging, the emission signal is collected through an optical fiber and transduced to an electrical signal via a photomultiplier tube (PMT). CL Images are registered in a panchromatic mode and can be filtered using a monochromator connected between the optical fiber and the PMT to produce monochromatic CL images. The designed system has been employed to study ZnO samples prepared by electrical arc discharge and microwave methods. CL images are compared with SE images and chemical elemental mapping images to correlate the emission regions of the sample.

  11. Comparative study of image contrast in scanning electron microscope and helium ion microscope.

    Science.gov (United States)

    O'Connell, R; Chen, Y; Zhang, H; Zhou, Y; Fox, D; Maguire, P; Wang, J J; Rodenburg, C

    2017-12-01

    Images of Ga + -implanted amorphous silicon layers in a 110 n-type silicon substrate have been collected by a range of detectors in a scanning electron microscope and a helium ion microscope. The effects of the implantation dose and imaging parameters (beam energy, dwell time, etc.) on the image contrast were investigated. We demonstrate a similar relationship for both the helium ion microscope Everhart-Thornley and scanning electron microscope Inlens detectors between the contrast of the images and the Ga + density and imaging parameters. These results also show that dynamic charging effects have a significant impact on the quantification of the helium ion microscope and scanning electron microscope contrast. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  12. Magnetic imaging with a Zernike-type phase plate in a transmission electron microscope

    DEFF Research Database (Denmark)

    Pollard, Shawn; Malac, Marek; Beleggia, Marco

    2013-01-01

    We demonstrate the use of a hole-free phase plate (HFPP) for magnetic imaging in transmission electron microscopy by mapping the domain structure in PrDyFeB samples. The HFPP, a Zernike-like imaging method, allows for detecting magnetic signals in-focus to correlate the sample crystal structure...... the reference wave distortion from long-range fields affecting electron holography....

  13. Scanning tunnelling microscope imaging of nanoscale electron density gradients on the surface of GaAs

    International Nuclear Information System (INIS)

    Hamilton, B; Jacobs, J; Missous, M

    2003-01-01

    This paper is concerned with the scanning tunnelling microscope tunnelling conditions needed to produce constant current images dominated either by surface topology or by electronic effects. A model experimental structure was produced by cleaving a GaAs multiδ-doped layer in UHV and so projecting a spatially varying electron gas density onto the (110) surface. This cross sectional electron density varies on a nanometre scale in the [100] growth direction. The electronic structure and tunnelling properties of this system were modelled, and the tunnelling conditions favouring sensitivity to the surface electron gas density determined

  14. Sparse sampling and reconstruction for electron and scanning probe microscope imaging

    Science.gov (United States)

    Anderson, Hyrum; Helms, Jovana; Wheeler, Jason W.; Larson, Kurt W.; Rohrer, Brandon R.

    2015-07-28

    Systems and methods for conducting electron or scanning probe microscopy are provided herein. In a general embodiment, the systems and methods for conducting electron or scanning probe microscopy with an undersampled data set include: driving an electron beam or probe to scan across a sample and visit a subset of pixel locations of the sample that are randomly or pseudo-randomly designated; determining actual pixel locations on the sample that are visited by the electron beam or probe; and processing data collected by detectors from the visits of the electron beam or probe at the actual pixel locations and recovering a reconstructed image of the sample.

  15. Diffraction and depths-of-field effects in electron beam imaging at SURF III

    International Nuclear Information System (INIS)

    Arp, U.

    2001-01-01

    Imaging an electron beam with visible light is a common method of diagnostics applied to electron accelerators. It is a straightforward way to deduce the transverse electron distribution as well as its changes over time. The electrons stored in the Synchrotron Ultraviolet Radiation Facility (SURF) III at the National Institute of Standards and Technology (NIST) were studied over an extended period of time to characterize the upgraded accelerator. There is good agreement between experimental and theoretical horizontal beam sizes at three different electron energies

  16. A photomultiplier-based secondary electron imaging system for a nuclear microprobe

    International Nuclear Information System (INIS)

    Alves, L.C.; Breese, M.B.H.; Silva, M.F. da; Soares, J.C.

    2002-01-01

    The ability to define, or recognise particular regions of interest or surface features is vital to the analysis and interpretation of spatially-resolved images collected with a nuclear microprobe. However, good topographic image contrast is difficult to accomplish using PIXE or RBS images due to their inherent insensitivity to topography, lack of elemental variation or poor statistics. Topographic image contrast is commonly obtained in scanning electron microscopy (SEM) by detecting a large flux of secondary electrons produced by the focused keV electron beam. Similar systems have not been widely used on nuclear microprobes due to ion beam intensity fluctuations, which limit the minimum resolvable contrast and present a major limitation for this technique. This paper describes a secondary electron imaging system which has been developed on the Lisbon microprobe. It is based on a scintillator, a photomultiplier operated in a pulsed mode, a pulse shaping electronic chain and ADC, and requires no changes to the existing data acquisition system. Examples of the images obtained from materials such as patterned SiGe wafers and hydrogen-implanted silicon are given, and compared with SEM or optical images

  17. Trends in the electronic X-ray image formation and processing

    International Nuclear Information System (INIS)

    Meyer-Ebrecht, D.; Spiesberger, W.

    1976-01-01

    A report is given on the technological progress in components for the electronic imaging and reproduction in X-ray diagnostics which could enable the partial replacement of radiophotography. Furthermore, electronic post processing methods, in particular in tomography, are reviewed. (ORU) [de

  18. Predicting Electron Population Characteristics in 2-D Using Multispectral Ground-Based Imaging

    Science.gov (United States)

    Grubbs, Guy; Michell, Robert; Samara, Marilia; Hampton, Donald; Jahn, Jorg-Micha

    2018-01-01

    Ground-based imaging and in situ sounding rocket data are compared to electron transport modeling for an active inverted-V type auroral event. The Ground-to-Rocket Electrodynamics-Electrons Correlative Experiment (GREECE) mission successfully launched from Poker Flat, Alaska, on 3 March 2014 at 11:09:50 UT and reached an apogee of approximately 335 km over the aurora. Multiple ground-based electron-multiplying charge-coupled device (EMCCD) imagers were positioned at Venetie, Alaska, and aimed toward magnetic zenith. The imagers observed the intensity of different auroral emission lines (427.8, 557.7, and 844.6 nm) at the magnetic foot point of the rocket payload. Emission line intensity data are correlated with electron characteristics measured by the GREECE onboard electron spectrometer. A modified version of the GLobal airglOW (GLOW) model is used to estimate precipitating electron characteristics based on optical emissions. GLOW predicted the electron population characteristics with 20% error given the observed spectral intensities within 10° of magnetic zenith. Predictions are within 30% of the actual values within 20° of magnetic zenith for inverted-V-type aurora. Therefore, it is argued that this technique can be used, at least in certain types of aurora, such as the inverted-V type presented here, to derive 2-D maps of electron characteristics. These can then be used to further derive 2-D maps of ionospheric parameters as a function of time, based solely on multispectral optical imaging data.

  19. A new apparatus for electron-ion multiple coincidence momentum imaging spectroscopy

    International Nuclear Information System (INIS)

    Morishita, Y.; Kato, M.; Pruemper, G.; Liu, X.-J.; Lischke, T.; Ueda, K.; Tamenori, Y.; Oura, M.; Yamaoka, H.; Suzuki, I.H.; Saito, N.

    2006-01-01

    We have developed a new experimental apparatus for the electron-ion multiple coincidence momentum imaging spectroscopy in order to obtain the angular distributions of vibration-resolved photoelectrons from molecules fixed in space. The apparatus consists of a four-stage molecular supersonic jet and a spectrometer analyzing three-dimensional momenta of fragment ions and electrons in coincidence

  20. Novel low-dose imaging technique for characterizing atomic structures through scanning transmission electron microscope

    Science.gov (United States)

    Su, Chia-Ping; Syu, Wei-Jhe; Hsiao, Chien-Nan; Lai, Ping-Shan; Chen, Chien-Chun

    2017-08-01

    To investigate dislocations or heterostructures across interfaces is now of great interest to condensed matter and materials scientists. With the advances in aberration-corrected electron optics, the scanning transmission electron microscope has demonstrated its excellent capability of characterizing atomic structures within nanomaterials, and well-resolved atomic-resolution images can be obtained through long-exposure data acquisition. However, the sample drifting, carbon contamination, and radiation damage hinder further analysis, such as deriving three-dimensional (3D) structures from a series of images. In this study, a method for obtaining atomic-resolution images with significantly reduced exposure time was developed, using which an original high-resolution image with approximately one tenth the electron dose can be obtained by combining a fast-scan high-magnification image and a slow-scan low-magnification image. The feasibility of obtaining 3D atomic structures using the proposed approach was demonstrated through multislice simulation. Finally, the feasibility and accuracy of image restoration were experimentally verified. This general method cannot only apply to electron microscopy but also benefit to image radiation-sensitive materials using various light sources.

  1. A simple methodology for obtaining X-ray color images in scanning electron microscopy

    International Nuclear Information System (INIS)

    Veiga, M.M. da; Pietroluongo, L.R.V.

    1985-01-01

    A simple methodology for obtaining at least 3 elements X-ray images in only one photography is described. The fluorescent X-ray image is obtained from scanning electron microscopy with energy dispersion analysis system. The change of detector analytic channels, color cellophane foils and color films are used sequentially. (M.C.K.) [pt

  2. Soft X-ray imaging with axisymmetry microscope and electronic readout

    International Nuclear Information System (INIS)

    Sauneuf, A.; Cavailler, C.; Henry, Ph.; Launspach, J.; Mascureau, J. de; Rostaing, M.

    1984-11-01

    An axisymmetric microscope with 10 X magnification has been constructed; its resolution has been measured using severals grids, backlighted by an X-ray source and found to be near 25 μm. So it could be used to make images of laser driven plasmas in the soft X-ray region. In order to see rapidly those images we have associated it with a new detector. It is a small image converter tube with a soft X-ray photocathode and a P20 phosphor deposited on an optic fiber plate. The electronic image appearing on the screen is read by a CCD working in the spectral range. An electronic image readout chain, which is identical to those we use with streak cameras, then processes automatically and immediatly the images given by the microscope

  3. A Simple Metric for Determining Resolution in Optical, Ion, and Electron Microscope Images.

    Science.gov (United States)

    Curtin, Alexandra E; Skinner, Ryan; Sanders, Aric W

    2015-06-01

    A resolution metric intended for resolution analysis of arbitrary spatially calibrated images is presented. By fitting a simple sigmoidal function to pixel intensities across slices of an image taken perpendicular to light-dark edges, the mean distance over which the light-dark transition occurs can be determined. A fixed multiple of this characteristic distance is then reported as the image resolution. The prefactor is determined by analysis of scanning transmission electron microscope high-angle annular dark field images of Si. This metric has been applied to optical, scanning electron microscope, and helium ion microscope images. This method provides quantitative feedback about image resolution, independent of the tool on which the data were collected. In addition, our analysis provides a nonarbitrary and self-consistent framework that any end user can utilize to evaluate the resolution of multiple microscopes from any vendor using the same metric.

  4. Imaging of tissue sections with very slow electrons

    Czech Academy of Sciences Publication Activity Database

    Frank, Luděk; Nebesářová, Jana; Vancová, Marie; Paták, Aleš; Müllerová, Ilona

    2015-01-01

    Roč. 148, JAN 2015 (2015), s. 146-150 ISSN 0304-3991 R&D Projects: GA TA ČR TE01020118; GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 ; RVO:60077344 Keywords : Biological STEM * Ultralow energy STEM * Tissue sections * Cathode lens * Depolymerisation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.874, year: 2015

  5. Electron beam imaging and spectroscopy of plasmonic nanoantenna resonances

    NARCIS (Netherlands)

    Vesseur, P.C.

    2011-01-01

    Nanoantennas are metal structures that provide strong optical coupling between a nanoscale volume and the far field. This coupling is mediated by surface plasmons, oscillations of the free electrons in the metal. Increasing the control over the resonant plasmonic field distribution opens up a wide

  6. Modeling of Image Formation in Cryo-Electron Microscopy

    NARCIS (Netherlands)

    Vulovic, M.

    2013-01-01

    Knowledge of the structure of biological specimens is crucial for understanding life. Cryo-electron microscopy (cryo-EM) permits structural studies of biological specimen at their near-native state. The research performed in this thesis represents one of two subprojects of the FOM industrial

  7. Iplt--image processing library and toolkit for the electron microscopy community.

    Science.gov (United States)

    Philippsen, Ansgar; Schenk, Andreas D; Stahlberg, Henning; Engel, Andreas

    2003-01-01

    We present the foundation for establishing a modular, collaborative, integrated, open-source architecture for image processing of electron microscopy images, named iplt. It is designed around object oriented paradigms and implemented using the programming languages C++ and Python. In many aspects it deviates from classical image processing approaches. This paper intends to motivate developers within the community to participate in this on-going project. The iplt homepage can be found at http://www.iplt.org.

  8. Watermarking techniques for electronic delivery of remote sensing images

    Science.gov (United States)

    Barni, Mauro; Bartolini, Franco; Magli, Enrico; Olmo, Gabriella

    2002-09-01

    Earth observation missions have recently attracted a growing interest, mainly due to the large number of possible applications capable of exploiting remotely sensed data and images. Along with the increase of market potential, the need arises for the protection of the image products. Such a need is a very crucial one, because the Internet and other public/private networks have become preferred means of data exchange. A critical issue arising when dealing with digital image distribution is copyright protection. Such a problem has been largely addressed by resorting to watermarking technology. A question that obviously arises is whether the requirements imposed by remote sensing imagery are compatible with existing watermarking techniques. On the basis of these motivations, the contribution of this work is twofold: assessment of the requirements imposed by remote sensing applications on watermark-based copyright protection, and modification of two well-established digital watermarking techniques to meet such constraints. More specifically, the concept of near-lossless watermarking is introduced and two possible algorithms matching such a requirement are presented. Experimental results are shown to measure the impact of watermark introduction on a typical remote sensing application, i.e., unsupervised image classification.

  9. Elemental distribution imaging by energy-filtering transmission electron microscopy (EFTEM) and its applications

    International Nuclear Information System (INIS)

    Kurata, Hiroki

    1996-01-01

    EFTEM is new microscopy with the object of visualizing high resolution quantitative elemental distribution. The measurement principles and the present state of EFTEM studies are explained by the examples of measurement of the elemental distributions. EFTEM is a combination of the transmission electron microscope with the electron energy loss spectroscopy (EFLS). EFTEM method sets the slit in the specific energy field and put the electron passing the slit back in the microscopic image. The qualitative elemental analysis is obtained by observing the position of the absorption end of core electronic excitation spectrum and the quantitative one by determining the core electronic excitation strength of the specific atom depend on filtering with energy selector slit. The binding state and the local structure in the neighborhood of excited atom is determined by the fine structure of absorption end. By the chemical mapping method, the distribution image of chemical binding state is visualized by the imaging chemical map obtained by filtering the specific peak strength of fine structure with the narrow energy selector slit. The fine powder of lead chromate (PbCrO 4 ) covered with silica glass was shown as a typical example of the elemental distribution image of core electronic excitation spectrum. The quantitative analysis method of elemental distribution image is explained. The possibility of single atom analysis at nanometer was shown by the example of nanotube observed by EFTEM. (S.Y.)

  10. Experimental procedures to mitigate electron beam induced artifacts during in situ fluid imaging of nanomaterials

    International Nuclear Information System (INIS)

    Woehl, Taylor J.; Jungjohann, Katherine L.; Evans, James E.; Arslan, Ilke; Ristenpart, William D.; Browning, Nigel D.

    2013-01-01

    Scanning transmission electron microscopy of various fluid and hydrated nanomaterial samples has revealed multiple imaging artifacts and electron beam–fluid interactions. These phenomena include growth of crystals on the fluid stage windows, repulsion of particles from the irradiated area, bubble formation, and the loss of atomic information during prolonged imaging of individual nanoparticles. Here we provide a comprehensive review of these fluid stage artifacts, and we present new experimental evidence that sheds light on their origins in terms of experimental apparatus issues and indirect electron beam sample interactions with the fluid layer. A key finding is that many artifacts are a result of indirect electron beam interactions, such as production of reactive radicals in the water by radiolysis, and the associated crystal growth. The results presented here will provide a methodology for minimizing fluid stage imaging artifacts and acquiring quantitative in situ observations of nanomaterial behavior in a liquid environment

  11. Experimental procedures to mitigate electron beam induced artifacts during in situ fluid imaging of nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Woehl, Taylor J., E-mail: tjwoehl@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Jungjohann, Katherine L. [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Evans, James E. [Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616 (United States); Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Arslan, Ilke [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Ristenpart, William D. [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Department of Food Science and Technology, University of California, Davis, Davis, CA 95616 (United States); Browning, Nigel D. [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616 (United States); Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

    2013-04-15

    Scanning transmission electron microscopy of various fluid and hydrated nanomaterial samples has revealed multiple imaging artifacts and electron beam–fluid interactions. These phenomena include growth of crystals on the fluid stage windows, repulsion of particles from the irradiated area, bubble formation, and the loss of atomic information during prolonged imaging of individual nanoparticles. Here we provide a comprehensive review of these fluid stage artifacts, and we present new experimental evidence that sheds light on their origins in terms of experimental apparatus issues and indirect electron beam sample interactions with the fluid layer. A key finding is that many artifacts are a result of indirect electron beam interactions, such as production of reactive radicals in the water by radiolysis, and the associated crystal growth. The results presented here will provide a methodology for minimizing fluid stage imaging artifacts and acquiring quantitative in situ observations of nanomaterial behavior in a liquid environment.

  12. Electron diffraction, elemental and image analysis of nanocrystals

    Czech Academy of Sciences Publication Activity Database

    Šlouf, Miroslav; Pavlova, Ewa; Hromádková, Jiřina; Králová, Daniela; Tyrpekl, Václav

    2009-01-01

    Roč. 16, 2a (2009), s. 33-34 ISSN 1211-5894. [Struktura - Colloquium of Czech and Slovak Crystallographic Association. Hluboká nad Vltavou, 22.06.2009-25.06.2009] R&D Projects: GA AV ČR KAN200520704; GA ČR GA203/07/0717 Institutional research plan: CEZ:AV0Z40500505 Keywords : TEM * electron diffraction * nanocrystals Subject RIV: CD - Macromolecular Chemistry

  13. Free electron lifetime achievements in Liquid Argon Imaging TPC

    CERN Document Server

    Baibussinov, B; Calligarich, E; Centro, S; Cieslik, K; Farnese, C; Fava, A; Gibin, D; Guglielmi, A; Meng, G; Pietropaolo, F; Rubbia, C; Varanini, F; Ventura, S

    2010-01-01

    A key feature for the success of the Liquid Argon TPC technology is the industrial purification against electro-negative impurities, especially Oxygen and Nitrogen remnants, which have to be initially and continuously kept at an exceptional purity. New purification techniques have been applied to a 120 litres LAr-TPC test facility in the INFN-LNL laboratory. Through-going muon tracks have been used to monitor the LAr purity. The short path length used (30 cm) is compensated by the high accuracy in the observation of the specific ionization of cosmic rays muons at sea level. A free electron lifetime of (21.4+7.3-4.3) ms, namely > 15.8 ms at 90 % C.L. has been observed under stable conditions over several weeks, corresponding to about 15 ppt (part per trillion) of Oxygen equivalent. At 500 V/cm, where the electron speed is approximately of 1.5 mm/us, the free electron lifetime >15 ms corresponds to an attenuation <15 % for a drift path of 5 m, opening the way to reliable operation of LAr TPC for exceptionall...

  14. How well do time-integrated Kα images represent hot electron spatial distributions?

    Science.gov (United States)

    Ovchinnikov, V. M.; Kemp, G. E.; Schumacher, D. W.; Freeman, R. R.; Van Woerkom, L. D.

    2011-07-01

    A computational study is described, which addresses how well spatially resolved time-integrated Kα images recorded in intense laser-plasma experiments correlate with the distribution of "hot" (>1 MeV) electrons as they propagate through the target. The hot electron angular distribution leaving the laser-plasma region is critically important for many applications such as Fast Ignition or laser based x-ray sources; and Kα images are commonly used as a diagnostic. It is found that Kα images can easily mislead due to refluxing and other effects. Using the particle-in-cell code LSP, it is shown that a Kα image is not solely determined by the initial population of forward directed hot electrons, but rather also depends upon "delayed" hot electrons, and in fact continues to evolve long after the end of the laser interaction. Of particular note, there is a population of hot electrons created during the laser-plasma interaction that acquire a velocity direction opposite that of the laser and subsequently reflux off the front surface of the target, deflect when they encounter magnetic fields in the laser-plasma region, and then traverse the target in a wide spatial distribution. These delayed fast electrons create significant features in the Kα time-integrated images. Electrons refluxing from the sides and the back of the target are also found to play a significant role in forming the final Kα image. The relative contribution of these processes is found to vary depending on depth within target. These effects make efforts to find simple correlations between Kα images and, for example, Fast Ignition relevant parameters prone to error. Suggestions for future target design are provided.

  15. Management assessment using draft ANSI/ASQC-E4

    International Nuclear Information System (INIS)

    Hampton, E. Jr.

    1992-01-01

    Presented herein is a description of the process, methods, and techniques employed to conduct a comprehensive environmental management assessment of environmental waste management activities conducted by the Waste Management Department of Reynolds Electrical ampersand Engineering Co., Inc. (REECo) at the Nevada Test Site (NTS) using the draft ANSI/ASQC-E4 standard

  16. New developments in electron microscopy for serial image acquisition of neuronal profiles.

    Science.gov (United States)

    Kubota, Yoshiyuki

    2015-02-01

    Recent developments in electron microscopy largely automate the continuous acquisition of serial electron micrographs (EMGs), previously achieved by laborious manual serial ultrathin sectioning using an ultramicrotome and ultrastructural image capture process with transmission electron microscopy. The new systems cut thin sections and capture serial EMGs automatically, allowing for acquisition of large data sets in a reasonably short time. The new methods are focused ion beam/scanning electron microscopy, ultramicrotome/serial block-face scanning electron microscopy, automated tape-collection ultramicrotome/scanning electron microscopy and transmission electron microscope camera array. In this review, their positive and negative aspects are discussed. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. SEM technique for imaging and measuring electronic transport in nanocomposites based on electric field induced contrast

    Science.gov (United States)

    Jesse, Stephen [Knoxville, TN; Geohegan, David B [Knoxville, TN; Guillorn, Michael [Brooktondale, NY

    2009-02-17

    Methods and apparatus are described for SEM imaging and measuring electronic transport in nanocomposites based on electric field induced contrast. A method includes mounting a sample onto a sample holder, the sample including a sample material; wire bonding leads from the sample holder onto the sample; placing the sample holder in a vacuum chamber of a scanning electron microscope; connecting leads from the sample holder to a power source located outside the vacuum chamber; controlling secondary electron emission from the sample by applying a predetermined voltage to the sample through the leads; and generating an image of the secondary electron emission from the sample. An apparatus includes a sample holder for a scanning electron microscope having an electrical interconnect and leads on top of the sample holder electrically connected to the electrical interconnect; a power source and a controller connected to the electrical interconnect for applying voltage to the sample holder to control the secondary electron emission from a sample mounted on the sample holder; and a computer coupled to a secondary electron detector to generate images of the secondary electron emission from the sample.

  18. Ultrafast Imaging of Electronic Motion in Atoms and Molecules

    Science.gov (United States)

    2016-01-12

    that houses a faraday cup and a phosphor screen that is imaged onto a CCD camera. We first describe each component, and then the results of the...are generated by shining a UV laser pulse on a solid photocathode. The UV pulse is generated using a home-made frequency tripler (from 800 nm to 267...measured using a home-made retractable Faraday cup that can be moved in and out of the beam path, directly in front of the phosphor screen detector

  19. Cherenkov Ring Imaging Detector front-end electronics

    International Nuclear Information System (INIS)

    Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.; Marshall, D.; Muller, D.; Nagamine, T.; Oxoby, G.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Suekane, F.; Toge, N.; Va'Vra, J.; Williams, S.; Wilson, R.J.; Whitaker, J.S.; Bean, A.; Caldwell, D.; Duboscq, J.; Huber, J.; Lu, A.; Mathys, L.; McHugh, S.; Morrison, R.; Witherell, M.; Yellin, S.; Coyle, P.; Coyne, D.; Spencer, E.; d'Oliveira, A.; Johnson, R.A.; Martinez, J.; Nussbaum, M.; Santha, A.K.S.; Shoup, A.; Stockdale, I.; Jacques, P.; Plano, R.; Stamer, P.; Abe, K.; Hasegawa, K.; Yuta, H.

    1990-10-01

    The SLD Cherenkov Ring Imaging Detector use a proportional wire detector for which a single channel hybrid has been developed. It consists of a preamplifier, gain selectable amplifier, load driver amplifier, power switching, and precision calibrator. For this hybrid, a bipolar, semicustom integrated circuit has been designed which includes video operational amplifiers for two of the gain stages. This approach allows maximization of the detector volume, allows DC coupling, and enables gain selection. System tests show good noise performance, calibration precision, system linearity, and signal shape uniformity over the full dynamic range. 10 refs., 8 figs

  20. A Practical and Portable Solids-State Electronic Terahertz Imaging System

    Directory of Open Access Journals (Sweden)

    Ken Smart

    2016-04-01

    Full Text Available A practical compact solid-state terahertz imaging system is presented. Various beam guiding architectures were explored and hardware performance assessed to improve its compactness, robustness, multi-functionality and simplicity of operation. The system performance in terms of image resolution, signal-to-noise ratio, the electronic signal modulation versus optical chopper, is evaluated and discussed. The system can be conveniently switched between transmission and reflection mode according to the application. A range of imaging application scenarios was explored and images of high visual quality were obtained in both transmission and reflection mode.

  1. New Insights on Subsurface Imaging of Carbon Nanotubes in Polymer Composites via Scanning Electron Microscopy

    Science.gov (United States)

    Zhao, Minhua; Ming, Bin; Kim, Jae-Woo; Gibbons, Luke J.; Gu, Xiaohong; Nguyen, Tinh; Park, Cheol; Lillehei, Peter T.; Villarrubia, J. S.; Vladar, Andras E.; hide

    2015-01-01

    Despite many studies of subsurface imaging of carbon nanotube (CNT)-polymer composites via scanning electron microscopy (SEM), significant controversy exists concerning the imaging depth and contrast mechanisms. We studied CNT-polyimide composites and, by threedimensional reconstructions of captured stereo-pair images, determined that the maximum SEM imaging depth was typically hundreds of nanometers. The contrast mechanisms were investigated over a broad range of beam accelerating voltages from 0.3 to 30 kV, and ascribed to modulation by embedded CNTs of the effective secondary electron (SE) emission yield at the polymer surface. This modulation of the SE yield is due to non-uniform surface potential distribution resulting from current flows due to leakage and electron beam induced current. The importance of an external electric field on SEM subsurface imaging was also demonstrated. The insights gained from this study can be generally applied to SEM nondestructive subsurface imaging of conducting nanostructures embedded in dielectric matrices such as graphene-polymer composites, silicon-based single electron transistors, high resolution SEM overlay metrology or e-beam lithography, and have significant implications in nanotechnology.

  2. Imaging properties and energy aberrations of a double-pass cylindrical-mirror electron energy analyzer

    International Nuclear Information System (INIS)

    Erickson, N.E.; Powell, C.J.

    1986-01-01

    The imaging properties and energy aberrations of a commercial double-pass cylindrical-mirror analyzer have been characterized using an extension of the method recently reported by Seah and Mathieu. The electron beam from the coaxial electron gun was rastered across a test surface and the intensity of either elastically scattered electrons or of electrons at other selected energies was stored in a computer as a function of beam position on the specimen and other experimental parameters. The intensity data were later plotted to provide an ''image'' of the detected intensity. Images of this type are presented for electron energies of 100, 500, and 1000 eV and for the application of small offset voltages (typically between -1 and +5 V) between the analyzer and the gun cathode with the instrument operated in conditions appropriate for XPS or AES. Small offset voltages ( or approx. =5 V) lead to image shapes similar to those for the elastic peak but with 20%--40% increased widths. Deflection of the incident beam by up to 2 mm from the axis caused variations of up to +-0.15 eV in the measured positions of the elastic peak. Our observations can be interpreted qualitatively in terms of the known relationship between detected signal and combinations of position of electron emission from the specimen, angle of emission, and electron energy. The images obtained with elastically and inelastically scattered electrons provide a convenient and quantitative means of assessing instrument performance and of defining the specimen area being analyzed for the particular combination of instrument operating conditions and the energy width of AES or XPS features from the specimen

  3. Estimation of four-dimensional dose distribution using electronic portal imaging device in radiation therapy

    International Nuclear Information System (INIS)

    Mizoguchi, Asumi; Arimura, Hidetaka; Shioyama, Yoshiyuki

    2013-01-01

    We are developing a method to evaluate four-dimensional radiation dose distribution in a patient body based upon the animated image of EPID (electronic portal imaging device) which is an image of beam-direction at the irradiation. In the first place, we have obtained the image of the dose which is emitted from patient body at therapy planning using therapy planning CT image and dose evaluation algorism. In the second place, we have estimated the emission dose image at the irradiation using EPID animated image which is obtained at the irradiation. In the third place, we have got an affine transformation matrix including respiratory movement in the body by performing linear registration on the emission dose image at therapy planning to get the one at the irradiation. In the fourth place, we have applied the affine transformation matrix on the therapy planning CT image and estimated the CT image 'at irradiation'. Finally we have evaluated four-dimensional dose distribution by calculating dose distribution in the CT image 'at irradiation' which has been estimated for each frame of the EPID animated-image. This scheme may be useful for evaluating therapy results and risk management. (author)

  4. Investigation of bulk electron densities for dose calculations on cone-beam CT images

    International Nuclear Information System (INIS)

    Lambert, J.; Parker, J.; Gupta, S.; Hatton, J.; Tang, C.; Capp, A.; Denham, J.W.; Wright, P.

    2010-01-01

    Full text: If cone-beam CT images are to be used for dose calculations, then the images must be able to provide accurate electron density information. Twelve patients underwent twice weekly cone-beam CT scans in addition to the planning CT scan. A standardised 5-field treatment plan was applied to 169 of the CBCT images. Doses were calculated using the original electron density values in the CBCT and with bulk electron densities applied. Bone was assigned a density of 288 HU, and all other tissue was assigned to be water equivalent (0 HU). The doses were compared to the dose calculated on the original planning CT image. Using the original HU values in the cone-beam images, the average dose del i vered by the plans from all 12 patients was I. I % lower than the intended 200 cOy delivered on the original CT plans (standard devia tion 0.7%, maximum difference -2.93%). When bulk electron densities were applied to the cone-beam images, the average dose was 0.3% lower than the original CT plans (standard deviation 0.8%, maximum difference -2.22%). Compared to using the original HU values, applying bulk electron densities to the CBCT images improved the dose calculations by almost I %. Some variation due to natural changes in anatomy should be expected. The application of bulk elec tron densities to cone beam CT images has the potential to improve the accuracy of dose calculations due to inaccurate H U values. Acknowledgements This work was partially funded by Cancer Council NSW Grant Number RG 07-06.

  5. Magnetic nanoparticle imaging using multiple electron paramagnetic resonance activation sequences

    International Nuclear Information System (INIS)

    Coene, A.; Dupré, L.; Crevecoeur, G.

    2015-01-01

    Magnetic nanoparticles play an important role in several biomedical applications such as hyperthermia, drug targeting, and disease detection. To realize an effective working of these applications, the spatial distribution of the particles needs to be accurately known, in a non-invasive way. Electron Paramagnetic Resonance (EPR) is a promising and sensitive measurement technique for recovering these distributions. In the conventional approach, EPR is applied with a homogeneous magnetic field. In this paper, we employ different heterogeneous magnetic fields that allow to stabilize the solution of the associated inverse problem and to obtain localized spatial information. A comparison is made between the two approaches and our novel adaptation shows an average increase in reconstruction quality by 5% and is 12 times more robust towards noise. Furthermore, our approach allows to speed up the EPR measurements while still obtaining reconstructions with an improved accuracy and noise robustness compared to homogeneous EPR

  6. Counterfeit Electronics Detection Using Image Processing and Machine Learning

    Science.gov (United States)

    Asadizanjani, Navid; Tehranipoor, Mark; Forte, Domenic

    2017-01-01

    Counterfeiting is an increasing concern for businesses and governments as greater numbers of counterfeit integrated circuits (IC) infiltrate the global market. There is an ongoing effort in experimental and national labs inside the United States to detect and prevent such counterfeits in the most efficient time period. However, there is still a missing piece to automatically detect and properly keep record of detected counterfeit ICs. Here, we introduce a web application database that allows users to share previous examples of counterfeits through an online database and to obtain statistics regarding the prevalence of known defects. We also investigate automated techniques based on image processing and machine learning to detect different physical defects and to determine whether or not an IC is counterfeit.

  7. Counterfeit Electronics Detection Using Image Processing and Machine Learning

    International Nuclear Information System (INIS)

    Asadizanjani, Navid; Tehranipoor, Mark; Forte, Domenic

    2017-01-01

    Counterfeiting is an increasing concern for businesses and governments as greater numbers of counterfeit integrated circuits (IC) infiltrate the global market. There is an ongoing effort in experimental and national labs inside the United States to detect and prevent such counterfeits in the most efficient time period. However, there is still a missing piece to automatically detect and properly keep record of detected counterfeit ICs. Here, we introduce a web application database that allows users to share previous examples of counterfeits through an online database and to obtain statistics regarding the prevalence of known defects. We also investigate automated techniques based on image processing and machine learning to detect different physical defects and to determine whether or not an IC is counterfeit. (paper)

  8. Generation of low KV x-ray portal images with mega-voltage electron beams

    International Nuclear Information System (INIS)

    Kenny, J.; Ebert, M.

    2004-01-01

    Full text: The increasing complexity of radiation therapy plans and reduced target margins, have made accurate localization of patients at treatment a crucial quality assurance issue. Mega-voltage portal images, the standard for treatment localization, are inherently low in contrast because x-ray attenuation at these energies is similar for most body tissues. Thus anatomical features are difficult to distinguish and match to features on a reference diagnostic image. This project investigates the possibly of using x-rays created by an external target placed in the path of a clinical mega-voltage electron beam. This target is optimised to produce a higher proportion of useful imaging x-rays in the range of 50-200kV. It is thought that a high efficiency Varian aSi500 amorphous silicon EPID will be sufficient to compensate for the very low efficiency of x-ray production. The project was undertaken with concurrent theoretical and experimental components. The former involved Monte Carlo models of low Z target design while in the later, experimental data was gathered to validate the model and explore the practical issues associated with electron mode image acquisition. A 6 MeV electron beam model for a Varian Clinac 21EX was developed with EGS4/BEAMnrc User Code and compared to measured beam data. Phase space data scored at the secondary collimator then became the input for simulations of a target placed in the accessory tray. Target materials were predominately low atomic number (Z) because a) production of high energy x-rays is minimized and, b) fewer low energy x-rays produced will be absorbed within the target. Photon and electron energy spectrums of the modified beam were evaluated for a range of target geometries. Ultimately, several materials were used in combination to optimise an x-ray yield for energies <200kV while removing electrons and very low energy x-rays, that contribute to patient dose but not to image formation. Low energy images of a PIPs EPID QA

  9. High-speed multi-frame dynamic transmission electron microscope image acquisition system with arbitrary timing

    Science.gov (United States)

    Reed, Bryan W.; DeHope, William J.; Huete, Glenn; LaGrange, Thomas B.; Shuttlesworth, Richard M.

    2016-02-23

    An electron microscope is disclosed which has a laser-driven photocathode and an arbitrary waveform generator (AWG) laser system ("laser"). The laser produces a train of temporally-shaped laser pulses each being of a programmable pulse duration, and directs the laser pulses to the laser-driven photocathode to produce a train of electron pulses. An image sensor is used along with a deflector subsystem. The deflector subsystem is arranged downstream of the target but upstream of the image sensor, and has a plurality of plates. A control system having a digital sequencer controls the laser and a plurality of switching components, synchronized with the laser, to independently control excitation of each one of the deflector plates. This allows each electron pulse to be directed to a different portion of the image sensor, as well as to enable programmable pulse durations and programmable inter-pulse spacings.

  10. High-speed multiframe dynamic transmission electron microscope image acquisition system with arbitrary timing

    Science.gov (United States)

    Reed, Bryan W.; DeHope, William J.; Huete, Glenn; LaGrange, Thomas B.; Shuttlesworth, Richard M.

    2015-10-20

    An electron microscope is disclosed which has a laser-driven photocathode and an arbitrary waveform generator (AWG) laser system ("laser"). The laser produces a train of temporally-shaped laser pulses of a predefined pulse duration and waveform, and directs the laser pulses to the laser-driven photocathode to produce a train of electron pulses. An image sensor is used along with a deflector subsystem. The deflector subsystem is arranged downstream of the target but upstream of the image sensor, and has two pairs of plates arranged perpendicular to one another. A control system controls the laser and a plurality of switching components synchronized with the laser, to independently control excitation of each one of the deflector plates. This allows each electron pulse to be directed to a different portion of the image sensor, as well as to be provided with an independently set duration and independently set inter-pulse spacings.

  11. Imaging of soft and hard materials using a Boersch phase plate in a transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Alloyeau, D., E-mail: alloyeau.damien@gmail.com [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, One Cyclotron Road, MS/72, Berkeley, CA 94720 (United States); Hsieh, W.K. [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, One Cyclotron Road, MS/72, Berkeley, CA 94720 (United States); Anderson, E.H.; Hilken, L. [Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley CA 94720 (United States); Benner, G. [Carl Zeiss NTS GmbH, Oberkochen 73447 (Germany); Meng, X. [Electrical Engineering and Computer Sciences, UC Berkeley, Berkeley, CA 94720-1770 (United States); Chen, F.R. [Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan (China); Kisielowski, C. [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, One Cyclotron Road, MS/72, Berkeley, CA 94720 (United States)

    2010-04-15

    Using two levels of electron beam lithography, vapor phase deposition techniques, and FIB etching, we have fabricated an electrostatic Boersch phase plate for contrast enhancement of weak phase objects in a transmission electron microscope. The phase plate has suitable dimensions for the imaging of small biological samples without compromising the high-resolution capabilities of the microscope. A micro-structured electrode allows for phase tuning of the unscattered electron beam, which enables the recording of contrast enhanced in-focus images and in-line holograms. We have demonstrated experimentally that our phase plate improves the contrast of carbon nanotubes while maintaining high-resolution imaging performance, which is demonstrated for the case of an AlGaAs heterostructure. The development opens a new way to study interfaces between soft and hard materials.

  12. Iterative Stable Alignment and Clustering of 2D Transmission Electron Microscope Images

    Science.gov (United States)

    Yang, Zhengfan; Fang, Jia; Chittuluru, Johnathan; Asturias, Francisco J.; Penczek, Pawel A.

    2012-01-01

    SUMMARY Identification of homogeneous subsets of images in a macromolecular electron microscopy (EM) image data set is a critical step in single-particle analysis. The task is handled by iterative algorithms, whose performance is compromised by the compounded limitations of image alignment and K-means clustering. Here we describe an approach, iterative stable alignment and clustering (ISAC) that, relying on a new clustering method and on the concepts of stability and reproducibility, can extract validated, homogeneous subsets of images. ISAC requires only a small number of simple parameters and, with minimal human intervention, can eliminate bias from two-dimensional image clustering and maximize the quality of group averages that can be used for ab initio three-dimensional structural determination and analysis of macromolecular conformational variability. Repeated testing of the stability and reproducibility of a solution within ISAC eliminates heterogeneous or incorrect classes and introduces critical validation to the process of EM image clustering. PMID:22325773

  13. Vertical one-dimensional electron cyclotron emission imaging diagnostic for HT-7 tokamak

    International Nuclear Information System (INIS)

    Wang Jun; Xu Xiaoyuan; Wen Yizhi; Yu Changxuan; Wan Baonian; Luhmann, N.C.; Wang, Jian; Xia, Z.G.

    2005-01-01

    A vertical resolved 16-channel electron cyclotron emission imaging (ECEI) diagnostic has been developed and installed on the HT7 Tokamak for measuring plasma electron cyclotron emission with a temporal resolution of 0.5 us. The system is working on a fixed frequency 97.5 GHz in the first stage. The sample volumes of the system are aligned vertically with a vertical channel spacing of 11 mm, and can be shifted across the plasma cross-section by varying the toroidal magnetic field. The high spatial resolution of the system is achieved by utilizing a low cost linear mixer/receiver array and an optical imaging system. The focus location may be shifted horizontally via translation of one of the optical imaging elements. The detail of the system design and laboratory testing of the ECE Imaging optics are presented, together with HT7 plasma data. (author)

  14. Can X-ray spectrum imaging replace backscattered electrons for compositional contrast in the scanning electron microscope?

    Science.gov (United States)

    Newbury, Dale E; Ritchie, Nicholas W M

    2011-01-01

    The high throughput of the silicon drift detector energy dispersive X-ray spectrometer (SDD-EDS) enables X-ray spectrum imaging (XSI) in the scanning electron microscope to be performed in frame times of 10-100 s, the typical time needed to record a high-quality backscattered electron (BSE) image. These short-duration XSIs can reveal all elements, except H, He, and Li, present as major constituents, defined as 0.1 mass fraction (10 wt%) or higher, as well as minor constituents in the range 0.01-0.1 mass fraction, depending on the particular composition and possible interferences. Although BSEs have a greater abundance by a factor of 100 compared with characteristic X-rays, the strong compositional contrast in element-specific X-ray maps enables XSI mapping to compete with BSE imaging to reveal compositional features. Differences in the fraction of the interaction volume sampled by the BSE and X-ray signals lead to more delocalization of the X-ray signal at abrupt compositional boundaries, resulting in poorer spatial resolution. Improved resolution in X-ray elemental maps occurs for the case of a small feature composed of intermediate to high atomic number elements embedded in a matrix of lower atomic number elements. XSI imaging strongly complements BSE imaging, and the SDD-EDS technology enables an efficient combined BSE-XSI measurement strategy that maximizes the compositional information. If 10 s or more are available for the measurement of an area of interest, the analyst should always record the combined BSE-XSI information to gain the advantages of both measures of compositional contrast. Copyright © 2011 Wiley Periodicals, Inc.

  15. Picosecond imaging of inertial confinement fusion plasmas using electron pulse-dilation

    Science.gov (United States)

    Hilsabeck, T. J.; Nagel, S. R.; Hares, J. D.; Kilkenny, J. D.; Bell, P. M.; Bradley, D. K.; Dymoke-Bradshaw, A. K. L.; Piston, K.; Chung, T. M.

    2017-02-01

    Laser driven inertial confinement fusion (ICF) plasmas typically have burn durations on the order of 100 ps. Time resolved imaging of the x-ray self emission during the hot spot formation is an important diagnostic tool which gives information on implosion symmetry, transient features and stagnation time. Traditional x-ray gated imagers for ICF use microchannel plate detectors to obtain gate widths of 40-100 ps. The development of electron pulse-dilation imaging has enabled a 10X improvement in temporal resolution over legacy instruments. In this technique, the incoming x-ray image is converted to electrons at a photocathode. The electrons are accelerated with a time-varying potential that leads to temporal expansion as the electron signal transits the tube. This expanded signal is recorded with a gated detector and the effective temporal resolution of the composite system can be as low as several picoseconds. An instrument based on this principle, known as the Dilation X-ray Imager (DIXI) has been constructed and fielded at the National Ignition Facility. Design features and experimental results from DIXI will be presented.

  16. Extreme Ultraviolet Imaging of Electron Heated Targets in Petawatt Laser Experiments

    International Nuclear Information System (INIS)

    Ma, T.; MacPhee, A.; Key, M.; Akli, K.; Mackinnon, A.; Chen, C.; Barbee, T.; Freeman, R.; King, J.; Link, A.; Offermann, D.; Ovchinnikov, V.; Patel, P.; Stephens, R.; VanWoerkom, L.; Zhang, B.; Beg, F.

    2007-01-01

    The study of the transport of electrons, and the flow of energy into a solid target or dense plasma, is instrumental in the development of fast ignition inertial confinement fusion. An extreme ultraviolet (XUV) imaging diagnostic at 256 eV and 68 eV provides information about heating and energy deposition within petawatt laser-irradiated targets. XUV images of several irradiated solid targets are presented

  17. Light Distribution in the E3 and E4 Scintillation Counters of the ATLAS Tile Calorimeter

    CERN Document Server

    Hsu, Catherine

    2013-01-01

    The Tile Calorimeter (TileCal) of the ATLAS experiment is an important component of the ATLAS calorimetry because they play a crucial role in the search for new particles. The E3 and E4 are crack scintillators of TileCal that extend into the gap region between the EM barrel and EM endcaps. They thus sample the energy of the EM showers produced by particles interacting with the dead material in the EM calorimeters and with the inner detector cables. This project focuses on the study of the light collection uniformity in the E3 and E4 scintillating tiles using low energy electrons as the ionising particles. It is important to have uniform light response in the tiles because it would ensure a good energy resolution for the dead region. However, many factors affect the uniform light collection within the scintillating tiles.

  18. Towards native-state imaging in biological context in the electron microscope

    Science.gov (United States)

    Weston, Anne E.; Armer, Hannah E. J.

    2009-01-01

    Modern cell biology is reliant on light and fluorescence microscopy for analysis of cells, tissues and protein localisation. However, these powerful techniques are ultimately limited in resolution by the wavelength of light. Electron microscopes offer much greater resolution due to the shorter effective wavelength of electrons, allowing direct imaging of sub-cellular architecture. The harsh environment of the electron microscope chamber and the properties of the electron beam have led to complex chemical and mechanical preparation techniques, which distance biological samples from their native state and complicate data interpretation. Here we describe recent advances in sample preparation and instrumentation, which push the boundaries of high-resolution imaging. Cryopreparation, cryoelectron microscopy and environmental scanning electron microscopy strive to image samples in near native state. Advances in correlative microscopy and markers enable high-resolution localisation of proteins. Innovation in microscope design has pushed the boundaries of resolution to atomic scale, whilst automatic acquisition of high-resolution electron microscopy data through large volumes is finally able to place ultrastructure in biological context. PMID:19916039

  19. Dancing with the Electrons: Time-Domain and CW In Vivo EPR Imaging

    Directory of Open Access Journals (Sweden)

    Murali C. Krishna

    2008-01-01

    Full Text Available The progress in the development of imaging the distribution of unpaired electrons in living systems and the functional and the potential diagnostic dimensions of such an imaging process, using Electron Paramagnetic Resonance Imaging (EPRI, is traced from its origins with emphasis on our own work. The importance of EPR imaging stems from the fact that many paramagnetic probes show oxygen dependent spectral broadening. Assessment of in vivo oxygen concentration is an important factor in radiation oncology in treatment-planning and monitoring treatment-outcome. The emergence of narrow-line trairylmethyl based, bio-compatible spin probes has enabled the development of radiofrequency time-domain EPRI. Spectral information in time-domain EPRI can be achieved by generating a time sequence of T2* or T2 weighted images. Progress in CW imaging has led to the use of rotating gradients, more recently rapid scan with direct detection, and a combination of all the three. Very low field MRI employing Dynamic Nuclear polarization (Overhauser effect is also employed for monitoring tumor hypoxia, and re-oxygenation in vivo. We have also been working on the co-registration of MRI and time domain EPRI on mouse tumor models at 300 MHz using a specially designed resonator assembly. The mapping of the unpaired electron distribution and unraveling the spectral characteristics by using magnetic resonance in presence of stationary and rotating gradients in indeed ‘dancing with the (unpaired electrons’, metaphorically speaking.

  20. Dancing with the Electrons: Time-Domain and CW EPR Imaging

    Directory of Open Access Journals (Sweden)

    Sankaran Subramanian

    2008-01-01

    Full Text Available The progress in the development of imaging the distribution of unpaired electrons in living systems and the functional and the potential diagnostic dimensions of such an imaging process, using Electron Paramagnetic Resonance Imaging (EPRI, is traced from its origins with emphasis on our own work. The importance of EPR imaging stems from the fact that many paramagnetic probes show oxygen dependent spectral broadening. Assessment of in vivo oxygen concentration is an important factor in radiation oncology in treatment-planning and monitoring treatment-outcome. The emergence of narrow-line trairylmethyl based, bio-compatible spin probes has enabled the development of radiofrequency time-domain EPRI. Spectral information in time-domain EPRI can be achieved by generating a time sequence of T 2 * or T 2 weighted images. Progress in CW imaging has led to the use of rotating gradients, more recently rapid scan with direct detection, and a combination of all the three. Very low field MRI employing Dynamic Nuclear polarization (Overhauser effect is also employed for monitoring tumor hypoxia, and re-oxygenation in vivo . We have also been working on the co-registration of MRI and time domain EPRI on mouse tumor models at 300 MHz using a specially designed resonator assembly. The mapping of the unpaired electron distribution and unraveling the spectral characteristics by using magnetic resonance in presence of stationary and rotating gradients in indeed ‘dancing with the ( unpaired electrons’, metaphorically speaking.

  1. Dark-field imaging based on post-processed electron backscatter diffraction patterns of bulk crystalline materials in a scanning electron microscope.

    Science.gov (United States)

    Brodusch, Nicolas; Demers, Hendrix; Gauvin, Raynald

    2015-01-01

    Dark-field (DF) images were acquired in the scanning electron microscope with an offline procedure based on electron backscatter diffraction (EBSD) patterns (EBSPs). These EBSD-DF images were generated by selecting a particular reflection on the electron backscatter diffraction pattern and by reporting the intensity of one or several pixels around this point at each pixel of the EBSD-DF image. Unlike previous studies, the diffraction information of the sample is the basis of the final image contrast with a pixel scale resolution at the EBSP providing DF imaging in the scanning electron microscope. The offline facility of this technique permits the selection of any diffraction condition available in the diffraction pattern and displaying the corresponding image. The high number of diffraction-based images available allows a better monitoring of deformation structures compared to electron channeling contrast imaging (ECCI) which is generally limited to a few images of the same area. This technique was applied to steel and iron specimens and showed its high capability in describing more rigorously the deformation structures around micro-hardness indents. Due to the offline relation between the reference EBSP and the EBSD-DF images, this new technique will undoubtedly greatly improve our knowledge of deformation mechanism and help to improve our understanding of the ECCI contrast mechanisms. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Deblurring of class-averaged images in single-particle electron microscopy

    International Nuclear Information System (INIS)

    Park, Wooram; Chirikjian, Gregory S; Madden, Dean R; Rockmore, Daniel N

    2010-01-01

    This paper proposes a method for the deblurring of class-averaged images in single-particle electron microscopy (EM). Since EM images of biological samples are very noisy, the images which are nominally identical projection images are often grouped, aligned and averaged in order to cancel or reduce the background noise. However, the noise in the individual EM images generates errors in the alignment process, which creates an inherent limit on the accuracy of the resulting class averages. This inaccurate class average due to the alignment errors can be viewed as the result of a convolution of an underlying clear image with a blurring function. In this work, we develop a deconvolution method that gives an estimate for the underlying clear image from a blurred class-averaged image using precomputed statistics of misalignment. Since this convolution is over the group of rigid-body motions of the plane, SE(2), we use the Fourier transform for SE(2) in order to convert the convolution into a matrix multiplication in the corresponding Fourier space. For practical implementation we use a Hermite-function-based image modeling technique, because Hermite expansions enable lossless Cartesian-polar coordinate conversion using the Laguerre–Fourier expansions, and Hermite expansion and Laguerre–Fourier expansion retain their structures under the Fourier transform. Based on these mathematical properties, we can obtain the deconvolution of the blurred class average using simple matrix multiplication. Tests of the proposed deconvolution method using synthetic and experimental EM images confirm the performance of our method

  3. Optimization of Monochromated TEM for Ultimate Resolution Imaging and Ultrahigh Resolution Electron Energy Loss Spectroscopy

    KAUST Repository

    Lopatin, Sergei; Cheng, Bin; Liu, Wei-Ting; Tsai, Meng-Lin; He, Jr-Hau; Chuvilin, Andrey

    2017-01-01

    The performance of a monochromated transmission electron microscope with Wien type monochromator is optimized to achieve an extremely narrow energy spread of electron beam and an ultrahigh energy resolution with spectroscopy. The energy spread in the beam is improved by almost an order of magnitude as compared to specified values. The optimization involves both the monochromator and the electron energy loss detection system. We demonstrate boosted capability of optimized systems with respect to ultra-low loss EELS and sub-angstrom resolution imaging (in a combination with spherical aberration correction).

  4. The Advanced Gamma-ray Imaging System (AGIS) - Camera Electronics Development

    Science.gov (United States)

    Tajima, Hiroyasu; Bechtol, K.; Buehler, R.; Buckley, J.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Hanna, D.; Horan, D.; Humensky, B.; Karlsson, N.; Kieda, D.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Mukherjee, R.; Ong, R.; Otte, N.; Quinn, J.; Schroedter, M.; Swordy, S.; Wagner, R.; Wakely, S.; Weinstein, A.; Williams, D.; Camera Working Group; AGIS Collaboration

    2010-03-01

    AGIS, a next-generation imaging atmospheric Cherenkov telescope (IACT) array, aims to achieve a sensitivity level of about one milliCrab for gamma-ray observations in the energy band of 50 GeV to 100 TeV. Achieving this level of performance will require on the order of 50 telescopes with perhaps as many as 1M total electronics channels. The larger scale of AGIS requires a very different approach from the currently operating IACTs, with lower-cost and lower-power electronics incorporated into camera modules designed for high reliability and easy maintenance. Here we present the concept and development status of the AGIS camera electronics.

  5. Optimization of Monochromated TEM for Ultimate Resolution Imaging and Ultrahigh Resolution Electron Energy Loss Spectroscopy

    KAUST Repository

    Lopatin, Sergei

    2017-09-01

    The performance of a monochromated transmission electron microscope with Wien type monochromator is optimized to achieve an extremely narrow energy spread of electron beam and an ultrahigh energy resolution with spectroscopy. The energy spread in the beam is improved by almost an order of magnitude as compared to specified values. The optimization involves both the monochromator and the electron energy loss detection system. We demonstrate boosted capability of optimized systems with respect to ultra-low loss EELS and sub-angstrom resolution imaging (in a combination with spherical aberration correction).

  6. Dynamics of annular bright field imaging in scanning transmission electron microscopy

    International Nuclear Information System (INIS)

    Findlay, S.D.; Shibata, N.; Sawada, H.; Okunishi, E.; Kondo, Y.; Ikuhara, Y.

    2010-01-01

    We explore the dynamics of image formation in the so-called annular bright field mode in scanning transmission electron microscopy, whereby an annular detector is used with detector collection range lying within the cone of illumination, i.e. the bright field region. We show that this imaging mode allows us to reliably image both light and heavy columns over a range of thickness and defocus values, and we explain the contrast mechanisms involved. The role of probe and detector aperture sizes is considered, as is the sensitivity of the method to intercolumn spacing and local disorder.

  7. Testing an inversion method for estimating electron energy fluxes from all-sky camera images

    Directory of Open Access Journals (Sweden)

    N. Partamies

    2004-06-01

    Full Text Available An inversion method for reconstructing the precipitating electron energy flux from a set of multi-wavelength digital all-sky camera (ASC images has recently been developed by tomografia. Preliminary tests suggested that the inversion is able to reconstruct the position and energy characteristics of the aurora with reasonable accuracy. This study carries out a thorough testing of the method and a few improvements for its emission physics equations. We compared the precipitating electron energy fluxes as estimated by the inversion method to the energy flux data recorded by the Defense Meteorological Satellite Program (DMSP satellites during four passes over auroral structures. When the aurorae appear very close to the local zenith, the fluxes inverted from the blue (427.8nm filtered ASC images or blue and green line (557.7nm images together give the best agreement with the measured flux values. The fluxes inverted from green line images alone are clearly larger than the measured ones. Closer to the horizon the quality of the inversion results from blue images deteriorate to the level of the ones from green images. In addition to the satellite data, the precipitating electron energy fluxes were estimated from the electron density measurements by the EISCAT Svalbard Radar (ESR. These energy flux values were compared to the ones of the inversion method applied to over 100 ASC images recorded at the nearby ASC station in Longyearbyen. The energy fluxes deduced from these two types of data are in general of the same order of magnitude. In 35% of all of the blue and green image inversions the relative errors were less than 50% and in 90% of the blue and green image inversions less than 100%. This kind of systematic testing of the inversion method is the first step toward using all-sky camera images in the way in which global UV images have recently been used to estimate the energy fluxes. The advantages of ASCs, compared to the space-born imagers, are

  8. Time-resolved imaging of purely valence-electron dynamics during a chemical reaction

    DEFF Research Database (Denmark)

    Hockett, Paul; Bisgaard, Christer Z.; Clarkin, Owen J.

    2011-01-01

    Chemical reactions are manifestations of the dynamics of molecular valence electrons and their couplings to atomic motions. Emerging methods in attosecond science can probe purely electronic dynamics in atomic and molecular systems(1-6). By contrast, time-resolved structural-dynamics methods...... such as electron(7-10) or X-ray diffraction(11) and X-ray absorption(12) yield complementary information about the atomic motions. Time-resolved methods that are directly sensitive to both valence-electron dynamics and atomic motions include photoelectron spectroscopy(13-15) and high-harmonic generation(16......,17): in both cases, this sensitivity derives from the ionization-matrix element(18,19). Here we demonstrate a time-resolved molecular-frame photoelectron-angular-distribution (TRMFPAD) method for imaging the purely valence-electron dynamics during a chemical reaction. Specifically, the TRMFPADs measured during...

  9. Apolipoprotein E4 Allele and Gait Performance in Mild Cognitive Impairment: Results From the Gait and Brain Study.

    Science.gov (United States)

    Sakurai, Ryota; Montero-Odasso, Manuel

    2017-11-09

    The apolipoprotein E polymorphism ε4 allele (ApoE4) and gait impairment are both known risk factors for developing cognitive decline and dementia. However, it is unclear the interrelationship between these factors, particularly among older adults with mild cognitive impairment (MCI) who are considered as prodromal for Alzheimer's disease. This study aimed to determine whether ApoE4 carrier individuals with MCI may experience greater impairment in gait performance. Fifty-six older adults with MCI from the "Gait and Brain Study" who were identified as either ApoE4 carriers (n = 20) or non-ApoE4 carriers (n = 36) with 1 year of follow-up were included. Gait variability, the main outcome variable, was assessed as stride time variability with an electronic walkway. Additional gait variables and cognitive performance (mini-mental state examination [MMSE] and Montreal Cognitive Assessment [MoCA]) were also recorded. Covariates included age, sex, education level, body mass index, and number of comorbidities. Baseline characteristics were similar for both groups. Repeated measures analysis of covariance showed that gait stride time and stride length variabilities significantly increased in ApoE4 carriers but was maintained in the non-ApoE4 carriers. Similarly, ApoE4 carriers showed greater decrease in MMSE score at follow-up. In this sample of older adults with MCI, the presence of at least one copy of ApoE4 was associated with the development of both increased gait variability and cognitive decline during 1 year of follow-up. ApoE4 genotype might be considered as a potential mediator of decline in mobility function in MCI; future studies with larger samples are needed to confirm our preliminary findings. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. In Vivo Application of Proton-Electron Double-Resonance Imaging

    Science.gov (United States)

    Kishimoto, Shun; Krishna, Murali C.; Khramtsov, Valery V.; Utsumi, Hideo

    2018-01-01

    Abstract Significance: Proton-electron double-resonance imaging (PEDRI) employs electron paramagnetic resonance irradiation with low-field magnetic resonance imaging so that the electron spin polarization is transferred to nearby protons, resulting in higher signals. PEDRI provides information about free radical distribution and, indirectly, about the local microenvironment such as partial pressure of oxygen (pO2), tissue permeability, redox status, and acid-base balance. Recent Advances: Local acid-base balance can be imaged by exploiting the different resonance frequency of radical probes between R and RH+ forms. Redox status can also be imaged by using the loss of radical-related signal after reduction. These methods require optimized radical probes and pulse sequences. Critical Issues: High-power radio frequency irradiation is needed for optimum signal enhancement, which may be harmful to living tissue by unwanted heat deposition. Free radical probes differ depending on the purpose of PEDRI. Some probes are less effective for enhancing signal than others, which can reduce image quality. It is so far not possible to image endogenous radicals by PEDRI because low concentrations and broad line widths of the radicals lead to negligible signal enhancement. Future Directions: PEDRI has similarities with electron paramagnetic resonance imaging (EPRI) because both techniques observe the EPR signal, directly in the case of EPRI and indirectly with PEDRI. PEDRI provides information that is vital to research on homeostasis, development of diseases, or treatment responses in vivo. It is expected that the development of new EPR techniques will give insights into novel PEDRI applications and vice versa. Antioxid. Redox Signal. 28, 1345–1364. PMID:28990406

  11. Three-dimentional imaging of dentomaxillofacial region using electron beam tomography

    International Nuclear Information System (INIS)

    Tanaka, Takemasa; Kanda, Shigenobu; Muranaka, Toru

    1998-01-01

    Authors reported their results of the 3-D imaging of dentomaxillofacial region mainly for jaw deformity with electron beam tomography (EBT). The EBT apparatus used was Imatron C-100 (Imatron Corp.), with which, using bremsstrahlung radiation generated from the electron beam, CT is possible with rapid scanning rate at <0.1 sec. Imaging was done with those conditions as tube voltage: 130 kV, current: 610 mA, scanning rate: 0.1 sec/slice whose thickness was 1.5 mm, feeding rate: 1.5 mm and number of slices: 40-170. Patients were 15 cases with jaw deformity. Data were processed for 3-D image by Scribe Imaging Workstation (Multi-dimensional Imaging Inc.) which giving surface rendering and further by Power Macintosh 8500 (Apple Computer Inc.) with VoxBlast 1.1.0 (VayTec Inc.) software which giving volume rendering or with Image 1.60 (NIH) which allowing multi-planar reconstruction and re-analog projection. These actual images were presented in the report. (K.H.)

  12. PENGARUH ELECTRONIC WORD OF MOUTH (eWOM TWITTER @batikair TERHADAP BRAND IMAGE

    Directory of Open Access Journals (Sweden)

    Cherry Kartika

    2015-05-01

    Full Text Available This study aims to determine the influence of the Electronic Word of Mouth twitter @batikair in terms of the following dimensions are intensity dimension to the brand image, valence of opinion dimension to the brand image, and content dimension to the brand image.The sampling technique in this study using purposive sampling technique with criteria from Batik Air passengers in period of June 2015. The data in this study are primary data that collected through questionnaires. Data were analyzed using multiple regression analysis with the classical assumptions.Based on the results of data analysis and discussion, it can be concluded as follows: (1 There is eWOM twitter @batikair influence in terms of intensity dimension to the brand image. (2 There is a eWOM twitter @batikair influence in terms of valence of opinion dimension to the brand image. @batikair. (3 There is a positive eWOM twitter @batikair influence in terms of content dimension to the brand image, it means that the better available information from social network sites relating to products and services will be a positive influence on @batikairbrand image enhancement.   Penelitian ini bertujuan untuk mengetahui pengaruh Electronic Word of Mouth (eWOM twitter @batikair ditinjau dari dimensi-dimensi berikut yaitu dimensi intensity terhadap brand image, dimensi valence of opinion terhadap brand image, dan dimensi content terhadap brand image.Teknik pengambilan sampel pada penelitian ini menggunakan teknik purposive sampling dengan kriteria tertentu yaitu para penumpang Batik Air. Data pada penelitian ini adalah data primer yang dikumpulkan melalui kuesioner. Teknik analisis data menggunakan analisis regresi berganda dengan asumsi klasik.Berdasarkan pada hasil analisis data dan pembahasan maka dapat disimpulkan sebagai berikut: (1 Terdapat pengaruh eWOM twitter @batikair ditinjau dari dimensi intensity terhadap brand imag.e. (2 Terdapat pengaruh eWOM twitter @batikair ditinjau dari dimensi

  13. Reducing charging effects in scanning electron microscope images by Rayleigh contrast stretching method (RCS).

    Science.gov (United States)

    Wan Ismail, W Z; Sim, K S; Tso, C P; Ting, H Y

    2011-01-01

    To reduce undesirable charging effects in scanning electron microscope images, Rayleigh contrast stretching is developed and employed. First, re-scaling is performed on the input image histograms with Rayleigh algorithm. Then, contrast stretching or contrast adjustment is implemented to improve the images while reducing the contrast charging artifacts. This technique has been compared to some existing histogram equalization (HE) extension techniques: recursive sub-image HE, contrast stretching dynamic HE, multipeak HE and recursive mean separate HE. Other post processing methods, such as wavelet approach, spatial filtering, and exponential contrast stretching, are compared as well. Overall, the proposed method produces better image compensation in reducing charging artifacts. Copyright © 2011 Wiley Periodicals, Inc.

  14. Determination of line edge roughness in low-dose top-down scanning electron microscopy images

    NARCIS (Netherlands)

    Verduin, T.; Kruit, P.; Hagen, C.W.

    2014-01-01

    We investigated the off-line metrology for line edge roughness (LER) determination by using the discrete power spectral density (PSD). The study specifically addresses low-dose scanning electron microscopy (SEM) images in order to reduce the acquisition time and the risk of resist shrinkage. The

  15. 3D imaging by serial block face scanning electron microscopy for materials science using ultramicrotomy.

    Science.gov (United States)

    Hashimoto, Teruo; Thompson, George E; Zhou, Xiaorong; Withers, Philip J

    2016-04-01

    Mechanical serial block face scanning electron microscopy (SBFSEM) has emerged as a means of obtaining three dimensional (3D) electron images over volumes much larger than possible by focused ion beam (FIB) serial sectioning and at higher spatial resolution than achievable with conventional X-ray computed tomography (CT). Such high resolution 3D electron images can be employed for precisely determining the shape, volume fraction, distribution and connectivity of important microstructural features. While soft (fixed or frozen) biological samples are particularly well suited for nanoscale sectioning using an ultramicrotome, the technique can also produce excellent 3D images at electron microscope resolution in a time and resource-efficient manner for engineering materials. Currently, a lack of appreciation of the capabilities of ultramicrotomy and the operational challenges associated with minimising artefacts for different materials is limiting its wider application to engineering materials. Consequently, this paper outlines the current state of the art for SBFSEM examining in detail how damage is introduced during slicing and highlighting strategies for minimising such damage. A particular focus of the study is the acquisition of 3D images for a variety of metallic and coated systems. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  16. Periodic quality control of a linear accelerator using electronic portal imaging

    International Nuclear Information System (INIS)

    Planes Meseguer, D.; Dorado Rodriguez, M. P.; Esposito, R. D.

    2011-01-01

    In this paper we present our solution for the realization of the monthly periodic quality control (CP) geometry - mechanical and multi leaf collimator (MLC), using the electronic system for portal imaging (EPI). We have developed specific programs created with free software. The monitoring results are automatically stored on our web server, along with other information generated in our service.

  17. 77 FR 11588 - Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof

    Science.gov (United States)

    2012-02-27

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-831] Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof AGENCY: U.S. International Trade Commission... Trade Commission on January 10, 2012, under section 337 of the Tariff Act of 1930, as amended, 19 U.S.C...

  18. 75 FR 39971 - In the Matter of Certain Electronic Imaging Devices; Notice of Investigation

    Science.gov (United States)

    2010-07-13

    ... INTERNATIONAL TRADE COMMISSION [Inv. No. 337-TA-726] In the Matter of Certain Electronic Imaging Devices; Notice of Investigation AGENCY: U.S. International Trade Commission. ACTION: Institution of....S. International Trade Commission on May 13, 2010, under section 337 of the Tariff Act of 1930, as...

  19. Images of Complex Interactions of an Intense Ion Beam with Plasma Electrons

    International Nuclear Information System (INIS)

    Kaganovich, Igor D.; Startsev, Edward; Davidson, Ronald C.

    2004-01-01

    Ion beam propagation in a background plasma is an important scientific issue for many practical applications. The process of ion beam charge and current neutralization is complex because plasma electrons move in strong electric and magnetic fields of the beam. Computer simulation images of plasma interaction with an intense ion beam pulse are presented

  20. On the influence of the electron dose rate on the HRTEM image contrast

    Energy Technology Data Exchange (ETDEWEB)

    Barthel, Juri, E-mail: ju.barthel@fz-juelich.de [RWTH Aachen University, Ahornstraße 55, 52074 Aachen (Germany); Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Lentzen, Markus; Thust, Andreas [Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)

    2017-05-15

    We investigate a possible dependence between the applied electron dose-rate and the magnitude of the resulting image contrast in HRTEM of inorganic crystalline objects. The present study is focussed on the question whether electron irradiation can induce excessively strong atom vibrations or displacements, which in turn could significantly reduce the resulting image contrast. For this purpose, high-resolution images of MgO, Ge, and Au samples were acquired with varying dose rates using a C{sub S}-corrected FEI Titan 80–300 microscope operated at 300 kV accelerating voltage. This investigation shows that the magnitude of the signal contrast is independent from the dose rates occurring in conventional HRTEM experiments and that excessively strong vibrations or displacements of bulk atoms are not induced by the applied electron irradiation. - Highlights: • No dependence between electron dose rate and HRTEM image contrast is found. • This finding is in full accordance with established solid-state physics theory. • Object-related causes for the previous Stobbs-factor phenomenon are ruled out.

  1. Interpretation of secondary electron images obtained using a low vacuum SEM

    International Nuclear Information System (INIS)

    Toth, M.; Thiel, B.L.; Donald, A.M.

    2003-01-01

    Charging of insulators in a variable pressure environment was investigated in the context of secondary electron (SE) image formation. Sample charging and ionized gas molecules present in a low vacuum specimen chamber can give rise to SE image contrast. 'Charge-induced' SE contrast reflects lateral variations in the charge state of a sample caused by electron irradiation during and prior to image acquisition. This contrast corresponds to SE emission current alterations produced by sub-surface charge deposited by the electron beam. 'Ion-induced' contrast results from spatial inhomogeneities in the extent of SE signal inhibition caused by ions in the gaseous environment of a low vacuum scanning electron microscope (SEM). The inhomogeneities are caused by ion focusing onto regions of a sample that correspond to local minima in the magnitude of the surface potential (generated by sub-surface trapped charge), or topographic asperities. The two types of contrast exhibit characteristic dependencies on microscope operating parameters such as scan speed, beam current, gas pressure, detector bias and working distance. These dependencies, explained in terms of the behavior of the gaseous environment and sample charging, can serve as a basis for a correct interpretation of SE images obtained using a low vacuum SEM

  2. The effect of electronic word of mouth communication and brand image on purchase intention: A case of consumer electronics in Haripur, Pakistan

    Directory of Open Access Journals (Sweden)

    Anees Kazmi

    2016-07-01

    Full Text Available This study aims to focus on the purchase intention of the consumer specifically the millennial age group with respect to the effect of Electronic word of mouth communication and brand image. The study is performed among the students of the University of Haripur. Study reveals that the effect of Electronic word of mouth and brand image for the purchase of consumer electronics products have positively correlated and the effect is significant, which means that the Word of mouth communication can positively respond to the purchase of the said products in case when the products are branded and have certain image in the mind of consumer.

  3. Ab initio transmission electron microscopy image simulations of coherent Ag-MgO interfaces

    International Nuclear Information System (INIS)

    Mogck, S.; Kooi, B.J.; Hosson, J.Th.M. de; Finnis, M.W.

    2004-01-01

    Density-functional theory calculations, within the plane-wave-ultrasoft pseudopotential framework, were performed in the projection for MgO and for the coherent (111) Ag-MgO polar interface. First-principles calculations were incorporated in high-resolution transmission electron microscopy (HRTEM) simulations by converting the charge density into electron scattering factors to examine the influence of charge transfer, charge redistribution at the interface, and ionicity on the dynamical electron scattering and on calculated HRTEM images. It is concluded that the ionicity of oxides and the charge redistribution at interfaces play a significant role in HRTEM image simulations. In particular, the calculations show that at oxygen-terminated (111) Ag-MgO interfaces the first oxygen layer at the interface is much brighter than that in calculations with neutral atoms, in agreement with experimental observations

  4. Electronic structure and simulated STM images of non-honeycomb phosphorene allotropes

    Science.gov (United States)

    Kaur, Sumandeep; Kumar, Ashok; Srivastava, Sunita; Tankeshwar, K.

    2018-04-01

    We have investigated the electronic structure and simulated STM images of various non-honeycomb allotropes of phosphorene namely ɛ - P, ζ - P, η - P and θ - P, within combined density functional theory and Tersoff-Hamman approach. All these allotropes are found to be energetically stable and electronically semiconductingwith bandgap ranging between 0.5-1.2 eV. Simulated STM images show distinctly different features in terms of the topography. Different maximas in the distance-height profile indicates the difference in buckling of atoms in these allotropes. Distinctly different images obtained in this study may be useful to differentiate various allotropes that can serve as fingerprints to identify various allotropes during the synthesis of phosphorene.

  5. Correlative scanning electron and confocal microscopy imaging of labeled cells coated by indium-tin-oxide

    KAUST Repository

    Rodighiero, Simona

    2015-03-22

    Confocal microscopy imaging of cells allows to visualize the presence of specific antigens by using fluorescent tags or fluorescent proteins, with resolution of few hundreds of nanometers, providing their localization in a large field-of-view and the understanding of their cellular function. Conversely, in scanning electron microscopy (SEM), the surface morphology of cells is imaged down to nanometer scale using secondary electrons. Combining both imaging techniques have brought to the correlative light and electron microscopy, contributing to investigate the existing relationships between biological surface structures and functions. Furthermore, in SEM, backscattered electrons (BSE) can image local compositional differences, like those due to nanosized gold particles labeling cellular surface antigens. To perform SEM imaging of cells, they could be grown on conducting substrates, but obtaining images of limited quality. Alternatively, they could be rendered electrically conductive, coating them with a thin metal layer. However, when BSE are collected to detect gold-labeled surface antigens, heavy metals cannot be used as coating material, as they would mask the BSE signal produced by the markers. Cell surface could be then coated with a thin layer of chromium, but this results in a loss of conductivity due to the fast chromium oxidation, if the samples come in contact with air. In order to overcome these major limitations, a thin layer of indium-tin-oxide was deposited by ion-sputtering on gold-decorated HeLa cells and neurons. Indium-tin-oxide was able to provide stable electrical conductivity and preservation of the BSE signal coming from the gold-conjugated markers. © 2015 Wiley Periodicals, Inc.

  6. Actions improving the image of a nurse in electronic media. Opinion of students at medical courses

    Directory of Open Access Journals (Sweden)

    Jakubowska Klaudia

    2017-09-01

    Full Text Available Aim. The aim of study was to define actions improving the image of nurses in electronic media. Material and method. 219 women and 44 men took part in a survey. They were the students of the following courses: nursing, medical rescue, obstetrics, medicine, dentistry, pharmaceutics, physiotherapy, public health. The studies were undertaken with use of own questionnaire in 2015. Results. Majority of respondents 64,6% (n=169 stated that improvement of image of their own profession belongs to the nurses, and only 35,4% (n=93 respondents indicated that the professional organizations of nurses and midwives have their impact on it. According to the students, the most crucial action that should be undertaken by professional organizations in order to improve the image of profession in electronic media was the improvement of wages and working conditions (72,2%, n=189 and better promotion of the profession in electronic media (73,8%, n=193. The nurses can influence the improvement of their image in media by taking care of the good opinion about the profession by setting good example (32%, n=84, and also by creating blogs, social forum, online information services, etc. (26,2%, n=69. Conclusions. According to the respondents, the image of a nurse in electronic media is shaped by the television and radio. The mentioned media tend to present nursing environment in a negative light. The data analysis shows that according to the respondents, the professional organizations of nurses and midwives and nurses themselves should be responsible for improvement of the situation. In order to improve the image, the nurses should promote professional achievements, change the stereotype used in shows and movies, and familiarize the public with the profession. The following branches of mass media should be used: internet websites, television and radio.

  7. Use of an axisymmetric microscope with electronic readout for collecting soft X-ray images

    International Nuclear Information System (INIS)

    Cavailler, C.; Henry, P.; Launspach, J.; De Mascureau, J.; Millerioux, M.; Rostaing, M.; Sauneuf, R.

    1984-08-01

    The axisymmetric microscope, first discussed by Wolter, provides high resolution and sensitivity for investigating the soft X-ray emission of laser-driven plasmas. Such a device having a 10 X magnification has been constructed. We present a comparison between the images of laser-driven plasmas given by this microscope and by a 10 X pinhole camera. Until now these images were recorded on X-ray film. We have shown that film could be replaced by C.C.D. in a pinhole camera when the photon energy lies within the 1-10 keV range. Below 1 keV the quantum yield is too low so we have used an image converter tube made by RTC. It is a diode-inverter tube with a soft X-ray photocathode and a P20 phosphor deposited on an optic fiber plate. The electronic image appearing on the screen is read by a C.C.D. working in the visible spectral fields. An electronic image readout chain, which is identical to those associated with streak cameras, then processes automatically and immediately the images given by the microscope [fr

  8. Development of Geometrical Quality Control Real-time Analysis Program using an Electronic Portal Imaging

    International Nuclear Information System (INIS)

    Lee, Sang Rok; Jung, Kyung Yong; Jang, Min Sun; Lee, Byung Gu; Kwon, Young Ho

    2012-01-01

    To develop a geometrical quality control real-time analysis program using an electronic portal imaging to replace film evaluation method. A geometrical quality control item was established with the Eclipse treatment planning system (Version 8.1, Varian, USA) after the Electronic Portal Imaging Device (EPID) took care of the problems occurring from the fixed substructure of the linear accelerator (CL-iX, Varian, USA). Electronic portal image (single exposure before plan) was created at the treatment room's 4DTC (Version 10.2, Varian, USA) and a beam was irradiated in accordance with each item. The gaining the entire electronic portal imaging at the Off-line review and was evaluated by a self-developed geometrical quality control real-time analysis program. As for evaluation methods, the intra-fraction error was analyzed by executing 5 times in a row under identical conditions and procedures on the same day, and in order to confirm the infer-fraction error, it was executed for 10 days under identical conditions of all procedures and was compared with the film evaluation method using an Iso-align quality control device. Measurement and analysis time was measured by sorting the time into from the device setup to data achievement and the time amount after the time until the completion of analysis and the convenience of the users and execution processes were compared. The intra-fraction error values for each average 0.1, 0.2, 0.3, 0.2 mm at light-radiation field coincidence, collimator rotation axis, couch rotation axis and gantry rotation axis. By checking the infer-fraction error through 10 days of continuous quality control, the error values obtained were average 1.7, 1.4, 0.7, 1.1 mm for each item. Also, the measurement times were average 36 minutes, 15 minutes for the film evaluation method and electronic portal imaging system, and the analysis times were average 30 minutes, 22 minutes. When conducting a geometrical quality control using an electronic portal imaging

  9. ESTERR-PRO: A Setup Verification Software System Using Electronic Portal Imaging

    Directory of Open Access Journals (Sweden)

    Pantelis A. Asvestas

    2007-01-01

    Full Text Available The purpose of the paper is to present and evaluate the performance of a new software-based registration system for patient setup verification, during radiotherapy, using electronic portal images. The estimation of setup errors, using the proposed system, can be accomplished by means of two alternate registration methods. (a The portal image of the current fraction of the treatment is registered directly with the reference image (digitally reconstructed radiograph (DRR or simulator image using a modified manual technique. (b The portal image of the current fraction of the treatment is registered with the portal image of the first fraction of the treatment (reference portal image by applying a nearly automated technique based on self-organizing maps, whereas the reference portal has already been registered with a DRR or a simulator image. The proposed system was tested on phantom data and on data from six patients. The root mean square error (RMSE of the setup estimates was 0.8±0.3 (mean value ± standard deviation for the phantom data and 0.3±0.3 for the patient data, respectively, by applying the two methodologies. Furthermore, statistical analysis by means of the Wilcoxon nonparametric signed test showed that the results that were obtained by the two methods did not differ significantly (P value >0.05.

  10. Imaging nanoscale spatial modulation of a relativistic electron beam with a MeV ultrafast electron microscope

    Science.gov (United States)

    Lu, Chao; Jiang, Tao; Liu, Shengguang; Wang, Rui; Zhao, Lingrong; Zhu, Pengfei; Liu, Yaqi; Xu, Jun; Yu, Dapeng; Wan, Weishi; Zhu, Yimei; Xiang, Dao; Zhang, Jie

    2018-03-01

    An accelerator-based MeV ultrafast electron microscope (MUEM) has been proposed as a promising tool to the study structural dynamics at the nanometer spatial scale and the picosecond temporal scale. Here, we report experimental tests of a prototype MUEM where high quality images with nanoscale fine structures were recorded with a pulsed ˜3 MeV picosecond electron beam. The temporal and spatial resolutions of the MUEM operating in the single-shot mode are about 4 ps (FWHM) and 100 nm (FWHM), corresponding to a temporal-spatial resolution of 4 × 10-19 s m, about 2 orders of magnitude higher than that achieved with state-of-the-art single-shot keV UEM. Using this instrument, we offer the demonstration of visualizing the nanoscale periodic spatial modulation of an electron beam, which may be converted into longitudinal density modulation through emittance exchange to enable production of high-power coherent radiation at short wavelengths. Our results mark a great step towards single-shot nanometer-resolution MUEMs and compact intense x-ray sources that may have widespread applications in many areas of science.

  11. Calibration of imaging plates to electrons between 40 and 180 MeV

    International Nuclear Information System (INIS)

    Rabhi, N.; Batani, D.; Boutoux, G.; Ducret, J.-E.; Bohacek, K.; Guillaume, E.; Thaury, C.; Jakubowska, K.; Thfoin, I.

    2016-01-01

    This paper presents the response calibration of Imaging Plates (IPs) for electrons in the 40-180 MeV range using laser-accelerated electrons at Laboratoire d’Optique Appliquée (LOA), Palaiseau, France. In the calibration process, the energy spectrum and charge of electron beams are measured by an independent system composed of a magnetic spectrometer and a Lanex scintillator screen used as a calibrated reference detector. It is possible to insert IPs of different types or stacks of IPs in this spectrometer in order to detect dispersed electrons simultaneously. The response values are inferred from the signal on the IPs, due to an appropriate charge calibration of the reference detector. The effect of thin layers of tungsten in front and/or behind IPs is studied in detail. GEANT4 simulations are used in order to analyze our measurements.

  12. High-resolution electron microscope image analysis approach for superconductor YBa2Cu3O7-x

    International Nuclear Information System (INIS)

    Xu, J.; Lu, F.; Jia, C.; Hua, Z.

    1991-01-01

    In this paper, an HREM (High-resolution electron microscope) image analysis approach has been developed. The image filtering, segmentation and particles extraction based on gray-scale mathematical morphological operations, are performed on the original HREM image. The final image is a pseudocolor image, with the background removed, relatively uniform brightness, filtered slanting elongation, regular shape for every kind of particle, and particle boundaries that no longer touch each other so that the superconducting material structure can be shown clearly

  13. Generation of complete electronic nuclear medicine reports including static, dynamic and gated images

    International Nuclear Information System (INIS)

    Beretta, M.; Pilon, R.; Mut, F.

    2002-01-01

    Aim: To develop a procedure for the creation of nuclear medicine reports containing static and dynamic images. The reason for implementing this technique is the lack of adequate solutions for an electronic format of nuclear medicine results allowing for rapid transmission via e-mail, specially in the case of dynamic and gated SPECT studies, since functional data is best presented in dynamic mode. Material and Methods: Clinical images were acquired in static, whole body, dynamic and gated mode, corresponding to bone studies, diuretic renogram, radionuclide cystography and gated perfusion SPECT, as well as respective time-activity curves. Image files were imported from a dedicated nuclear medicine computer system (Elscint XPert) to a Windows-based PC through a standard ethernet network with TCP-IP communications protocol, using a software developed by us which permits the conversion from the manufacturer's original format into a bitmap format (.bmp) compatible with commercially available PC software. For cardiac perfusion studies, background was subtracted prior to transferring to reduce the amount of information in the file; this was not done for other type of studies because useful data could be eliminated. Dynamic images were then processed using commercial software to create animated files and stored in .gif format. Static images were re-sized and stored in .jpg format. Original color or gray scale was always preserved. All the graphic material was then merged with a previously prepared report text using HTML format. The report also contained reference diagrams to facilitate interpretation. The whole report was then compressed into a self-extractable file, ready to be sent by electronic mail. Reception of the material was visually checked for data integrity including image quality by two experienced nuclear medicine physicians. Results: The report presented allows for simultaneous visualization of the text, diagrams and images either static, dynamic, gated or

  14. An asynchronous, pipelined, electronic acquisition system for Active Matrix Flat-Panel Imagers (AMFPIs)

    CERN Document Server

    Huang, W; Berry, J; Maolinbay, M; Martelli, C; Mody, P; Nassif, S; Yeakey, M

    1999-01-01

    The development of a full-custom electronic acquisition system designed for readout of large-area active matrix flat-panel imaging arrays is reported. The arrays, which comprise two-dimensional matrices of pixels utilizing amorphous silicon thin-film transistors, are themselves under development for a wide variety of X-ray imaging applications. The acquisition system was specifically designed to facilitate detailed, quantitative investigations of the properties of these novel imaging arrays and contains significant enhancements compared to a previously developed acquisition system. These enhancements include pipelined preamplifier circuits to allow faster readout speed, expanded addressing capabilities allowing a maximum of 4096 array data lines, and on-board summing of image frames. The values of many acquisition system parameters, including timings and voltages, may be specified and downloaded from a host computer. Once acquisition is enabled, the system operates asynchronously of its host computer. The sys...

  15. Energetic electron precipitation in the aurora as determined by x-ray imaging

    International Nuclear Information System (INIS)

    Werden, S.C.

    1988-01-01

    This work examines two aspects of energetic-particle dynamics in the Earth's magnetosphere through the use of an x-ray imager flown from a stratospheric balloon in the auroral zone. The design and theory of this instrument is completely described, including the technique of image formation using an on-board microprocessor and a statistical analysis of the imaging process. Day-side energetic-electron precipitation is examined in the context of global energy dissipation during the substorm process. It is found that the relationship between events on the night side and the day side are considerably more complex that can be modeled with just a simple picture of drifting particles that induced instabilities, wave growth, and pitch-angle diffusion into the loss cone. The driving force for precipitation is probably not the presence of the energetic electrons (>30 keV) alone, but is influenced either by local effects or the less energetic component. The presence of small-scale structure, including gradients and complex motions in the precipitation region in the morning sector, suggests a local process influencing the rate of electron precipitation. The spatial and temporal evolution of a classic 5-15 second pulsating aurora during the post-breakup phase is also examined with the x-ray imager

  16. Refinement procedure for the image alignment in high-resolution electron tomography

    International Nuclear Information System (INIS)

    Houben, L.; Bar Sadan, M.

    2011-01-01

    High-resolution electron tomography from a tilt series of transmission electron microscopy images requires an accurate image alignment procedure in order to maximise the resolution of the tomogram. This is the case in particular for ultra-high resolution where even very small misalignments between individual images can dramatically reduce the fidelity of the resultant reconstruction. A tomographic-reconstruction based and marker-free method is proposed, which uses an iterative optimisation of the tomogram resolution. The method utilises a search algorithm that maximises the contrast in tomogram sub-volumes. Unlike conventional cross-correlation analysis it provides the required correlation over a large tilt angle separation and guarantees a consistent alignment of images for the full range of object tilt angles. An assessment based on experimental reconstructions shows that the marker-free procedure is competitive to the reference of marker-based procedures at lower resolution and yields sub-pixel accuracy even for simulated high-resolution data. -- Highlights: → Alignment procedure for electron tomography based on iterative tomogram contrast optimisation. → Marker-free, independent of object, little user interaction. → Accuracy competitive with fiducial marker methods and suited for high-resolution tomography.

  17. Optical and x-ray imaging of electron beams using synchrotron emission

    International Nuclear Information System (INIS)

    Wilke, M.

    1995-01-01

    In the case of very low emittance electron and positron storage ring beams, it is impossible to make intrusive measurements of beam properties without increasing the emittance and possibly disrupting the beam. In cases where electron or positron beams have high average power densities (such as free electron laser linacs), intrusive probes such as wires and optical transition radiation screens or Cherenkov emitting screens can be easily damaged or destroyed. The optical and x-ray emissions from the bends in the storage rings and often from linac bending magnets can be used to image the beam profile to obtain emittance information about the beam. The techniques, advantages and limitations of using both optical and x-ray synchrotron emission to measure beam properties are discussed and the possibility of single bunch imaging is considered. The properties of suitable imagers and converters such as phosphors are described. Examples of previous, existing and planned applications are given where available, including a pinhole imaging system currently being designed for the Advanced Photon Source at Argonne National Laboratory

  18. Optical and x-ray imaging of electron beams using synchrotron emission

    International Nuclear Information System (INIS)

    Wilke, M.D.

    1994-01-01

    In the case of very low eniittance electron and positron storage ring beams, it is impossible to make intrusive measurements of beam properties without increasing the emittance and possibly disrupting the beam. In cases where electron or positron beams have high average power densities (such as free electron laser linacs), intrusive probes such as wires and optical transition radiation screens or Cherenkov emitting screens can be easily damaged or destroyed. The optical and x-ray emissions from the bends in the storage rings and often from linac bending magnets can be used to image the beam profile to obtain emittance information about the beam. The techniques, advantages and limitations of using both optical and x-ray synchrotron emission to measure beam properties are discussed and the possibility of single bunch imaging is considered. The properties of suitable imagers and converters such as phosphors are described. Examples of previous, existing and planned applications are given where available, including a pinhole imaging system currently being designed for the Advanced Photon Source at Argonne National Laboratory

  19. Femtosecond few- to single-electron point-projection microscopy for nanoscale dynamic imaging

    Directory of Open Access Journals (Sweden)

    A. R. Bainbridge

    2016-03-01

    Full Text Available Femtosecond electron microscopy produces real-space images of matter in a series of ultrafast snapshots. Pulses of electrons self-disperse under space-charge broadening, so without compression, the ideal operation mode is a single electron per pulse. Here, we demonstrate femtosecond single-electron point projection microscopy (fs-ePPM in a laser-pump fs-e-probe configuration. The electrons have an energy of only 150 eV and take tens of picoseconds to propagate to the object under study. Nonetheless, we achieve a temporal resolution with a standard deviation of 114 fs (equivalent to a full-width at half-maximum of 269 ± 40 fs combined with a spatial resolution of 100 nm, applied to a localized region of charge at the apex of a nanoscale metal tip induced by 30 fs 800 nm laser pulses at 50 kHz. These observations demonstrate real-space imaging of reversible processes, such as tracking charge distributions, is feasible whilst maintaining femtosecond resolution. Our findings could find application as a characterization method, which, depending on geometry, could resolve tens of femtoseconds and tens of nanometres. Dynamically imaging electric and magnetic fields and charge distributions on sub-micron length scales opens new avenues of ultrafast dynamics. Furthermore, through the use of active compression, such pulses are an ideal seed for few-femtosecond to attosecond imaging applications which will access sub-optical cycle processes in nanoplasmonics.

  20. Development of Electron Tracking Compton Camera using micro pixel gas chamber for medical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kabuki, Shigeto; Hattori, Kaori [Department of Physics, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Kohara, Ryota [Hitachi Medical Corporation, Kashiwa, Chiba 277-0804 (Japan); Kunieda, Etsuo; Kubo, Atsushi [Department of Radiography, Keio University, Shinjuku-ku, Tokyo 160-8582 (Japan); Kubo, Hidetoshi; Miuchi, Kentaro [Department of Physics, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Nakahara, Tadaki [Department of Radiography, Keio University, Shinjuku-ku, Tokyo 160-8582 (Japan); Nagayoshi, Tsutomu; Nishimura, Hironobu; Okada, Yoko; Orito, Reiko; Sekiya, Hiroyuki [Department of Physics, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Shirahata, Takashi [Hitachi Medical Corporation, Kashiwa, Chiba 277-0804 (Japan); Takada, Atsushi [Department of Physics, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Tanimori, Toru [Department of Physics, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan)], E-mail: tanimori@cr.scphys.kyoto-u.ac.jp; Ueno, Kazuki [Department of Physics, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan)

    2007-10-01

    We have developed the Electron Tracking Compton Camera (ETCC) with reconstructing the 3-D tracks of the scattered electron in Compton process for both sub-MeV and MeV gamma rays. By measuring both the directions and energies of not only the recoil gamma ray but also the scattered electron, the direction of the incident gamma ray is determined for each individual photon. Furthermore, a residual measured angle between the recoil electron and scattered gamma ray is quite powerful for the kinematical background rejection. For the 3-D tracking of the electrons, the Micro Time Projection Chamber ({mu}-TPC) was developed using a new type of the micro pattern gas detector. The ETCC consists of this {mu}-TPC (10x10x8 cm{sup 3}) and the 6x6x13 mm{sup 3} GSO crystal pixel arrays with a flat panel photo-multiplier surrounding the {mu}-TPC for detecting recoil gamma rays. The ETCC provided the angular resolution of 6.6 deg. (FWHM) at 364 keV of {sup 131}I. A mobile ETCC for medical imaging, which is fabricated in a 1 m cubic box, has been operated since October 2005. Here, we present the imaging results for the line sources and the phantom of human thyroid gland using 364 keV gamma rays of {sup 131}I.

  1. Non parametric denoising methods based on wavelets: Application to electron microscopy images in low exposure time

    International Nuclear Information System (INIS)

    Soumia, Sid Ahmed; Messali, Zoubeida; Ouahabi, Abdeldjalil; Trepout, Sylvain; Messaoudi, Cedric; Marco, Sergio

    2015-01-01

    The 3D reconstruction of the Cryo-Transmission Electron Microscopy (Cryo-TEM) and Energy Filtering TEM images (EFTEM) hampered by the noisy nature of these images, so that their alignment becomes so difficult. This noise refers to the collision between the frozen hydrated biological samples and the electrons beam, where the specimen is exposed to the radiation with a high exposure time. This sensitivity to the electrons beam led specialists to obtain the specimen projection images at very low exposure time, which resulting the emergence of a new problem, an extremely low signal-to-noise ratio (SNR). This paper investigates the problem of TEM images denoising when they are acquired at very low exposure time. So, our main objective is to enhance the quality of TEM images to improve the alignment process which will in turn improve the three dimensional tomography reconstructions. We have done multiple tests on special TEM images acquired at different exposure time 0.5s, 0.2s, 0.1s and 1s (i.e. with different values of SNR)) and equipped by Golding beads for helping us in the assessment step. We herein, propose a structure to combine multiple noisy copies of the TEM images. The structure is based on four different denoising methods, to combine the multiple noisy TEM images copies. Namely, the four different methods are Soft, the Hard as Wavelet-Thresholding methods, Bilateral Filter as a non-linear technique able to maintain the edges neatly, and the Bayesian approach in the wavelet domain, in which context modeling is used to estimate the parameter for each coefficient. To ensure getting a high signal-to-noise ratio, we have guaranteed that we are using the appropriate wavelet family at the appropriate level. So we have chosen âĂIJsym8âĂİ wavelet at level 3 as the most appropriate parameter. Whereas, for the bilateral filtering many tests are done in order to determine the proper filter parameters represented by the size of the filter, the range parameter and the

  2. Image transfer with spatial coherence for aberration corrected transmission electron microscopes

    International Nuclear Information System (INIS)

    Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi

    2016-01-01

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field’s components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field’s derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope. - Highlights: • The formula of partial coherence for aberration corrected TEM is derived. • Transfer functions are calculated with several residual aberrations. • The calculated transfer function shows the characteristic damping. • The odd-symmetric wave aberrations can cause the attenuation of image via coherence. • The examples of aberration corrected TEM image simulations are shown.

  3. Dose patient verification during treatment using an amorphous silicon electronic portal imaging device in radiotherapy

    International Nuclear Information System (INIS)

    Berger, Lucie

    2006-01-01

    Today, amorphous silicon electronic portal imaging devices (aSi EPID) are currently used to check the accuracy of patient positioning. However, they are not use for dose reconstruction yet and more investigations are required to allow the use of an aSi EPID for routine dosimetric verification. The aim of this work is first to study the dosimetric characteristics of the EPID available at the Institut Curie and then, to check patient dose during treatment using these EPID. First, performance optimization of the Varian aS500 EPID system is studied. Then, a quality assurance system is set up in order to certify the image quality on a daily basis. An additional study on the dosimetric performance of the aS500 EPID is monitored to assess operational stability for dosimetry applications. Electronic portal imaging device is also a useful tool to improve IMRT quality control. The validation and the quality assurance of a portal dose image prediction system for IMRT pre-treatment quality control are performed. All dynamic IMRT fields are verified in clinical routine with the new method based on portal dosimetry. Finally, a new formalism for in vivo dosimetry using transit dose measured with EPID is developed and validated. The absolute dose measurement issue using aSi EPID is described and the midplane dose determination using in vivo dose measurements in combination with portal imaging is used with 3D-conformal-radiation therapy. (author) [fr

  4. Automated magnification calibration in transmission electron microscopy using Fourier analysis of replica images

    International Nuclear Information System (INIS)

    Laak, Jeroen A.W.M. van der; Dijkman, Henry B.P.M.; Pahlplatz, Martin M.M.

    2006-01-01

    The magnification factor in transmission electron microscopy is not very precise, hampering for instance quantitative analysis of specimens. Calibration of the magnification is usually performed interactively using replica specimens, containing line or grating patterns with known spacing. In the present study, a procedure is described for automated magnification calibration using digital images of a line replica. This procedure is based on analysis of the power spectrum of Fourier transformed replica images, and is compared to interactive measurement in the same images. Images were used with magnification ranging from 1,000x to 200,000x. The automated procedure deviated on average 0.10% from interactive measurements. Especially for catalase replicas, the coefficient of variation of automated measurement was considerably smaller (average 0.28%) compared to that of interactive measurement (average 3.5%). In conclusion, calibration of the magnification in digital images from transmission electron microscopy may be performed automatically, using the procedure presented here, with high precision and accuracy

  5. Image transfer with spatial coherence for aberration corrected transmission electron microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Hosokawa, Fumio, E-mail: hosokawa@bio-net.co.jp [BioNet Ltd., 2-3-28 Nishikityo, Tachikwa, Tokyo (Japan); Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8503 (Japan); Sawada, Hidetaka [JEOL (UK) Ltd., JEOL House, Silver Court, Watchmead, Welwyn Garden City, Herts AL7 1LT (United Kingdom); Shinkawa, Takao [BioNet Ltd., 2-3-28 Nishikityo, Tachikwa, Tokyo (Japan); Sannomiya, Takumi [Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8503 (Japan)

    2016-08-15

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field’s components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field’s derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope. - Highlights: • The formula of partial coherence for aberration corrected TEM is derived. • Transfer functions are calculated with several residual aberrations. • The calculated transfer function shows the characteristic damping. • The odd-symmetric wave aberrations can cause the attenuation of image via coherence. • The examples of aberration corrected TEM image simulations are shown.

  6. Characterization of a direct detection device imaging camera for transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Milazzo, Anna-Clare, E-mail: amilazzo@ncmir.ucsd.edu [University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093 (United States); Moldovan, Grigore [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Lanman, Jason [Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037 (United States); Jin, Liang; Bouwer, James C. [University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093 (United States); Klienfelder, Stuart [University of California at Irvine, Irvine, CA 92697 (United States); Peltier, Steven T.; Ellisman, Mark H. [University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093 (United States); Kirkland, Angus I. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Xuong, Nguyen-Huu [University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093 (United States)

    2010-06-15

    The complete characterization of a novel direct detection device (DDD) camera for transmission electron microscopy is reported, for the first time at primary electron energies of 120 and 200 keV. Unlike a standard charge coupled device (CCD) camera, this device does not require a scintillator. The DDD transfers signal up to 65 lines/mm providing the basis for a high-performance platform for a new generation of wide field-of-view high-resolution cameras. An image of a thin section of virus particles is presented to illustrate the substantially improved performance of this sensor over current indirectly coupled CCD cameras.

  7. Characterization of a direct detection device imaging camera for transmission electron microscopy

    International Nuclear Information System (INIS)

    Milazzo, Anna-Clare; Moldovan, Grigore; Lanman, Jason; Jin, Liang; Bouwer, James C.; Klienfelder, Stuart; Peltier, Steven T.; Ellisman, Mark H.; Kirkland, Angus I.; Xuong, Nguyen-Huu

    2010-01-01

    The complete characterization of a novel direct detection device (DDD) camera for transmission electron microscopy is reported, for the first time at primary electron energies of 120 and 200 keV. Unlike a standard charge coupled device (CCD) camera, this device does not require a scintillator. The DDD transfers signal up to 65 lines/mm providing the basis for a high-performance platform for a new generation of wide field-of-view high-resolution cameras. An image of a thin section of virus particles is presented to illustrate the substantially improved performance of this sensor over current indirectly coupled CCD cameras.

  8. X-ray imaging and spectroscopy of individual cobalt nanoparticles using photoemission electron microscopy

    International Nuclear Information System (INIS)

    Fraile Rodriguez, A.; Nolting, F.; Bansmann, J.; Kleibert, A.; Heyderman, L.J.

    2007-01-01

    Photoemission electron microscopy (PEEM) was employed for X-ray imaging and absorption spectroscopy of individual cobalt nanoparticles as small as 8 nm grown using an arc ion cluster source. Using lithographic markers on the samples we were able to identify the same particles with PEEM and scanning electron microscopy. Significant variations in the shape of the X-ray absorption spectra between different cobalt particles were detected. Furthermore, our data suggest that distinctive spectral information about the individual particles, such as the quenching of oxide-related features and changes in the cobalt L 3 -edge intensity, cancel out and cannot be detected in the measurement over an ensemble of particles

  9. Modulated electron-multiplied fluorescence lifetime imaging microscope: all-solid-state camera for fluorescence lifetime imaging.

    Science.gov (United States)

    Zhao, Qiaole; Schelen, Ben; Schouten, Raymond; van den Oever, Rein; Leenen, René; van Kuijk, Harry; Peters, Inge; Polderdijk, Frank; Bosiers, Jan; Raspe, Marcel; Jalink, Kees; Geert Sander de Jong, Jan; van Geest, Bert; Stoop, Karel; Young, Ian Ted

    2012-12-01

    We have built an all-solid-state camera that is directly modulated at the pixel level for frequency-domain fluorescence lifetime imaging microscopy (FLIM) measurements. This novel camera eliminates the need for an image intensifier through the use of an application-specific charge coupled device design in a frequency-domain FLIM system. The first stage of evaluation for the camera has been carried out. Camera characteristics such as noise distribution, dark current influence, camera gain, sampling density, sensitivity, linearity of photometric response, and optical transfer function have been studied through experiments. We are able to do lifetime measurement using our modulated, electron-multiplied fluorescence lifetime imaging microscope (MEM-FLIM) camera for various objects, e.g., fluorescein solution, fixed green fluorescent protein (GFP) cells, and GFP-actin stained live cells. A detailed comparison of a conventional microchannel plate (MCP)-based FLIM system and the MEM-FLIM system is presented. The MEM-FLIM camera shows higher resolution and a better image quality. The MEM-FLIM camera provides a new opportunity for performing frequency-domain FLIM.

  10. Development and clinical implementation of an enhanced display algorithm for use in networked electronic portal imaging

    International Nuclear Information System (INIS)

    Heuvel, Frank van den; Han, Ihn; Chungbin, Suzanne; Strowbridge, Amy; Tekyi-Mensah, Sam; Ragan, Don P.

    1999-01-01

    Purpose: To introduce and clinically validate a preprocessing algorithm that allows clinical images from an electronic portal imaging device (EPID) to be displayed on any computer monitor, without loss of clinical usability. The introduction of such a system frees EPI systems from the constraints of fixed viewing workstations and increases mobility of the images in a department. Methods and Materials: The preprocessing algorithm, together with its variable parameters is introduced. Clinically, the algorithm is tested using an observer study of 316 EPID images of the pelvic region in the framework of treatment of carcinoma of the cervix and endometrium. Both anterior-posterior (AP/PA) and latero-lateral (LAT) images were used. The images scored were taken from six different patients, five of whom were obese, female, and postmenopausal. The result is tentatively compared with results from other groups. The scoring system, based on the number of visible landmarks in the port, is proposed and validated. Validation was performed by having the observer panel score images with artificially induced noise levels. A comparative study was undertaken with a standard automatic window and leveling display technique. Finally, some case studies using different image sites and EPI detectors are presented. Results: The image quality for all images in this study was deemed to be clinically useful (mean score > 1). Most of the images received a score which was second highest (AP/PA landmarks ≥ 6 and LAT landmarks ≥ 5). Obesity, which has been an important factor determining the image quality, was not seen to be a factor here. Compared to standard techniques a highly significant improvement was determined with regard to clinical usefulness. The algorithm performs fast (less than 9 seconds) and needs no additional user interaction in most of the cases. The algorithm works well on both direct detection portal imagers and camera-based imagers whether analog or digital cameras

  11. An asynchronous, pipelined, electronic acquisition system for Active Matrix Flat-Panel Imagers (AMFPIs)

    Energy Technology Data Exchange (ETDEWEB)

    Huang, W.; Antonuk, L.E. E-mail: antonuk@umich.edu; Berry, J.; Maolinbay, M.; Martelli, C.; Mody, P.; Nassif, S.; Yeakey, M

    1999-07-11

    The development of a full-custom electronic acquisition system designed for readout of large-area active matrix flat-panel imaging arrays is reported. The arrays, which comprise two-dimensional matrices of pixels utilizing amorphous silicon thin-film transistors, are themselves under development for a wide variety of X-ray imaging applications. The acquisition system was specifically designed to facilitate detailed, quantitative investigations of the properties of these novel imaging arrays and contains significant enhancements compared to a previously developed acquisition system. These enhancements include pipelined preamplifier circuits to allow faster readout speed, expanded addressing capabilities allowing a maximum of 4096 array data lines, and on-board summing of image frames. The values of many acquisition system parameters, including timings and voltages, may be specified and downloaded from a host computer. Once acquisition is enabled, the system operates asynchronously of its host computer. The system allows image capture in both radiographic mode (corresponding to the capture of individual X-ray images), and fluoroscopic mode (corresponding to the capture of a continual series of X-ray images). A detailed description of the system architecture and the underlying motivations for the design is reported in this paper. (author)

  12. Electron-tracking Compton gamma-ray camera for small animal and phantom imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kabuki, Shigeto, E-mail: kabuki@cr.scphys.kyoto-u.ac.j [Department of Physics, Gradulate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Kimura, Hiroyuki; Amano, Hiroo [Department of Patho-functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Nakamoto, Yuji [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Kyoto 606-8507 (Japan); Kubo, Hidetoshi; Miuchi, Kentaro; Kurosawa, Shunsuke; Takahashi, Michiaki [Department of Physics, Gradulate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Kawashima, Hidekazu [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Kyoto 606-8507 (Japan); Ueda, Masashi [Radioisotopes Research Labaoratory, Kyoto University Hospital, Kyoto 606-8507 (Japan); Okada, Tomohisa [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Kyoto 606-8507 (Japan); Kubo, Atsushi; Kunieda, Etuso; Nakahara, Tadaki [Department of Radiology, Keio University School of Medicine, Tokyo 160-8582 (Japan); Kohara, Ryota; Miyazaki, Osamu; Nakazawa, Tetsuo; Shirahata, Takashi; Yamamoto, Etsuji [Application Development Office, Hitachi Medical Corporation, Chiba 277-0804 (Japan); Ogawa, Koichi [Department of Electronic Informatics, Faculty of Engineering, Hosei University, Tokyo 184-8584 (Japan)

    2010-11-01

    We have developed an electron-tracking Compton camera (ETCC) for medical use. Our ETCC has a wide energy dynamic range (200-1300 keV) and wide field of view (3 sr), and thus has potential for advanced medical use. To evaluate the ETCC, we imaged the head (brain) and bladder of mice that had been administered with F-18-FDG. We also imaged the head and thyroid gland of mice using double tracers of F-18-FDG and I-131 ions.

  13. Four-dimensional dose reconstruction through in vivo phase matching of cine images of electronic portal imaging device.

    Science.gov (United States)

    Yoon, Jihyung; Jung, Jae Won; Kim, Jong Oh; Yi, Byong Yong; Yeo, Inhwan

    2016-07-01

    A method is proposed to reconstruct a four-dimensional (4D) dose distribution using phase matching of measured cine images to precalculated images of electronic portal imaging device (EPID). (1) A phantom, designed to simulate a tumor in lung (a polystyrene block with a 3 cm diameter embedded in cork), was placed on a sinusoidally moving platform with an amplitude of 1 cm and a period of 4 s. Ten-phase 4D computed tomography (CT) images of the phantom were acquired. A planning target volume (PTV) was created by adding a margin of 1 cm around the internal target volume of the tumor. (2) Three beams were designed, which included a static beam, a theoretical dynamic beam, and a planning-optimized dynamic beam (PODB). While the theoretical beam was made by manually programming a simplistic sliding leaf motion, the planning-optimized beam was obtained from treatment planning. From the three beams, three-dimensional (3D) doses on the phantom were calculated; 4D dose was calculated by means of the ten phase images (integrated over phases afterward); serving as "reference" images, phase-specific EPID dose images under the lung phantom were also calculated for each of the ten phases. (3) Cine EPID images were acquired while the beams were irradiated to the moving phantom. (4) Each cine image was phase-matched to a phase-specific CT image at which common irradiation occurred by intercomparing the cine image with the reference images. (5) Each cine image was used to reconstruct dose in the phase-matched CT image, and the reconstructed doses were summed over all phases. (6) The summation was compared with forwardly calculated 4D and 3D dose distributions. Accounting for realistic situations, intratreatment breathing irregularity was simulated by assuming an amplitude of 0.5 cm for the phantom during a portion of breathing trace in which the phase matching could not be performed. Intertreatment breathing irregularity between the time of treatment and the time of planning CT was

  14. Four-dimensional dose reconstruction through in vivo phase matching of cine images of electronic portal imaging device

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jihyung; Jung, Jae Won, E-mail: jungj@ecu.edu [Department of Physics, East Carolina University, Greenville, North Carolina 27858 (United States); Kim, Jong Oh [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15232 (United States); Yi, Byong Yong [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201 (United States); Yeo, Inhwan [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92354 (United States)

    2016-07-15

    Purpose: A method is proposed to reconstruct a four-dimensional (4D) dose distribution using phase matching of measured cine images to precalculated images of electronic portal imaging device (EPID). Methods: (1) A phantom, designed to simulate a tumor in lung (a polystyrene block with a 3 cm diameter embedded in cork), was placed on a sinusoidally moving platform with an amplitude of 1 cm and a period of 4 s. Ten-phase 4D computed tomography (CT) images of the phantom were acquired. A planning target volume (PTV) was created by adding a margin of 1 cm around the internal target volume of the tumor. (2) Three beams were designed, which included a static beam, a theoretical dynamic beam, and a planning-optimized dynamic beam (PODB). While the theoretical beam was made by manually programming a simplistic sliding leaf motion, the planning-optimized beam was obtained from treatment planning. From the three beams, three-dimensional (3D) doses on the phantom were calculated; 4D dose was calculated by means of the ten phase images (integrated over phases afterward); serving as “reference” images, phase-specific EPID dose images under the lung phantom were also calculated for each of the ten phases. (3) Cine EPID images were acquired while the beams were irradiated to the moving phantom. (4) Each cine image was phase-matched to a phase-specific CT image at which common irradiation occurred by intercomparing the cine image with the reference images. (5) Each cine image was used to reconstruct dose in the phase-matched CT image, and the reconstructed doses were summed over all phases. (6) The summation was compared with forwardly calculated 4D and 3D dose distributions. Accounting for realistic situations, intratreatment breathing irregularity was simulated by assuming an amplitude of 0.5 cm for the phantom during a portion of breathing trace in which the phase matching could not be performed. Intertreatment breathing irregularity between the time of treatment and the

  15. Secondary signal imaging (SSI) electron tomography (SSI-ET): A new three-dimensional metrology for mesoscale specimens in transmission electron microscope.

    Science.gov (United States)

    Han, Chang Wan; Ortalan, Volkan

    2015-09-01

    We have demonstrated a new electron tomography technique utilizing the secondary signals (secondary electrons and backscattered electrons) for ultra thick (a few μm) specimens. The Monte Carlo electron scattering simulations reveal that the amount of backscattered electrons generated by 200 and 300keV incident electrons is a monotonic function of the sample thickness and this causes the thickness contrast satisfying the projection requirement for the tomographic reconstruction. Additional contribution of the secondary electrons emitted from the edges of the specimens enhances the visibility of the surface features. The acquired SSI tilt series of the specimen having mesoscopic dimensions are successfully reconstructed verifying that this new technique, so called the secondary signal imaging electron tomography (SSI-ET), can directly be utilized for 3D structural analysis of mesoscale structures. Published by Elsevier Ltd.

  16. Scanning electron microscope cathodoluminescence imaging of subgrain boundaries, twins and planar deformation features in quartz

    Science.gov (United States)

    Hamers, M. F.; Pennock, G. M.; Drury, M. R.

    2017-04-01

    The study of deformation features has been of great importance to determine deformation mechanisms in quartz. Relevant microstructures in both growth and deformation processes include dislocations, subgrains, subgrain boundaries, Brazil and Dauphiné twins and planar deformation features (PDFs). Dislocations and twin boundaries are most commonly imaged using a transmission electron microscope (TEM), because these cannot directly be observed using light microscopy, in contrast to PDFs. Here, we show that red-filtered cathodoluminescence imaging in a scanning electron microscope (SEM) is a useful method to visualise subgrain boundaries, Brazil and Dauphiné twin boundaries. Because standard petrographic thin sections can be studied in the SEM, the observed structures can be directly and easily correlated to light microscopy studies. In contrast to TEM preparation methods, SEM techniques are non-destructive to the area of interest on a petrographic thin section.

  17. Energy-filtered real- and k-space secondary and energy-loss electron imaging with Dual Emission Electron spectro-Microscope: Cs/Mo(110)

    Energy Technology Data Exchange (ETDEWEB)

    Grzelakowski, Krzysztof P., E-mail: k.grzelakowski@opticon-nanotechnology.com

    2016-05-15

    Since its introduction the importance of complementary k{sub ||}-space (LEED) and real space (LEEM) information in the investigation of surface science phenomena has been widely demonstrated over the last five decades. In this paper we report the application of a novel kind of electron spectromicroscope Dual Emission Electron spectroMicroscope (DEEM) with two independent electron optical channels for reciprocal and real space quasi-simultaneous imaging in investigation of a Cs covered Mo(110) single crystal by using the 800 eV electron beam from an “in-lens” electron gun system developed for the sample illumination. With the DEEM spectromicroscope it is possible to observe dynamic, irreversible processes at surfaces in the energy-filtered real space and in the corresponding energy-filtered k{sub ǁ}-space quasi-simultaneously in two independent imaging columns. The novel concept of the high energy electron beam sample illumination in the cathode lens based microscopes allows chemically selective imaging and analysis under laboratory conditions. - Highlights: • A novel concept of the electron sample illumination with “in-lens” e- gun is realized. • Quasi-simultaneous energy selective observation of the real- and k-space in EELS mode. • Observation of the energy filtered Auger electron diffraction at Cs atoms on Mo(110). • Energy-loss, Auger and secondary electron momentum microscopy is realized.

  18. The determination of parameters of shower initiated in imaging calorimeter by electrons and protons

    International Nuclear Information System (INIS)

    Borisov, S.V.; Voronov, S.A.; Karelin, A.V.; Koldobskij, S.A.; Runtso, M.F.

    2010-01-01

    In this work the report on several methods of shower axis reconstruction and methods of search for the starting point of the shower are presented. They were developed for 'thin' sampling imaging calorimeters. For this purpose we used a Monte-Carlo simulation of interaction of electrons and protons with a silicon-tungsten calorimeter of PAMELA satellite-borne experiment. After some adaptation, these methods could be applied for different types of calorimeters

  19. 3D imaging by serial block face scanning electron microscopy for materials science using ultramicrotomy

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Teruo, E-mail: t.hashimoto@manchester.ac.uk; Thompson, George E.; Zhou, Xiaorong; Withers, Philip J.

    2016-04-15

    Mechanical serial block face scanning electron microscopy (SBFSEM) has emerged as a means of obtaining three dimensional (3D) electron images over volumes much larger than possible by focused ion beam (FIB) serial sectioning and at higher spatial resolution than achievable with conventional X-ray computed tomography (CT). Such high resolution 3D electron images can be employed for precisely determining the shape, volume fraction, distribution and connectivity of important microstructural features. While soft (fixed or frozen) biological samples are particularly well suited for nanoscale sectioning using an ultramicrotome, the technique can also produce excellent 3D images at electron microscope resolution in a time and resource-efficient manner for engineering materials. Currently, a lack of appreciation of the capabilities of ultramicrotomy and the operational challenges associated with minimising artefacts for different materials is limiting its wider application to engineering materials. Consequently, this paper outlines the current state of the art for SBFSEM examining in detail how damage is introduced during slicing and highlighting strategies for minimising such damage. A particular focus of the study is the acquisition of 3D images for a variety of metallic and coated systems. - Highlights: • The roughness of the ultramicrotomed block face of AA2024 in Al area was 1.2 nm. • Surface texture associated with chattering was evident in grains with 45° diamond knife. • A 76° rake angle minimises the stress on the block face. • Using the oscillating knife with a cutting speed of 0.04 mms{sup −1} minimised the surface texture. • A variety of material applications were presented.

  20. RGB color coded images in scanning electron microscopy of biological surfaces

    Czech Academy of Sciences Publication Activity Database

    Kofroňová, Olga; Benada, Oldřich

    2017-01-01

    Roč. 61, č. 3 (2017), s. 349-352 ISSN 0001-723X R&D Projects: GA MŠk(CZ) LO1509; GA ČR(CZ) GA16-20229S Institutional support: RVO:61388971 Keywords : Biological surfaces * Color image s * Scanning electron microscopy Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 0.673, year: 2016

  1. Deeply trapped electrons in imaging plates and their utilization for extending the dynamic range

    International Nuclear Information System (INIS)

    Ohuchi, Hiroko; Kondo, Yasuhiro

    2010-01-01

    The absorption spectra of deep centers in an imaging plate (IP) made of BaFBr 0:85 I 0:15 :Eu 2+ have been studied in the ultraviolet region. Electrons trapped in deep centers are considered to be the cause of unerasable and reappearing latent images in IPs over-irradiated with X-rays. Deep centers showed a dominant peak at around 320 nm, followed by two small peaks at around 345 and 380 nm. By utilizing deeply trapped electrons, we have attempted to extend the dynamic range of an IP. The IP was irradiated by 150-kV X-rays with doses from 8.07 mGy to 80.7 Gy. Reading out the latent image by the stimulation of Eu 2+ luminescence with a 633-nm He-Ne laser light from a conventional Fuji reader showed a linear relationship with irradiated dose up to 0.8 Gy, but then becoming non-linear. After fully erasing with visible light, unerasable latent images were read out using 635-nm semi-conductor laser light combined with a photon-counting detection system. The dose-response curve so obtained gave a further two orders of magnitude extending the dynamic range up to 80.7 Gy. Comprehensive results indicate that electrons supplied from deep centers to the F centers provided the extended dynamic range after the F centers became saturated. Based on these facts, a model of the excitation of deeply trapped electrons and PSL processes is proposed.

  2. E4 - Energy efficient elevators and escalators. Monitoring campaign - Germany

    Energy Technology Data Exchange (ETDEWEB)

    Hirzel, Simon; Boege, Christian

    2009-12-15

    A monitoring campaign was carried out within the E4 project as a contribution to improving the understanding of energy consumption and energy efficiency of elevators and escalators in Europe. The aim of this campaign is to broaden the empirical base on the energy consumption of elevators and escalators, to provide publicly available monitoring data and to find hints on system configurations using little energy. Originally, 50 installations were planned to be monitored within the project. In the end, 74 elevators and 7 escalators, i.e. a total of 81 installations, were analyzed in the four countries under study: Portugal, Poland, Italy and Germany. The aim of this document is to summarize the results of the German monitoring campaign with its 14 installations (13 elevators, 1 escalator) and to provide interested readers with some additional information on the campaign. This document has six parts: Second, after the introductory section, some general information on the monitoring methodology is provided as a background for understanding and interpreting the subsequent results. In the third part, information on the monitored elevator installations and their characteristics is given. Part four is concerned with presenting and discussing the results of the monitoring campaign for the elevators while part five shortly presents the results for the monitored escalator. Finally, some conclusions are found in the last part. (orig.)

  3. Urinary leukotriene E4 at 12 months and influencing factors

    Directory of Open Access Journals (Sweden)

    K Stencel-Gabriel

    2016-01-01

    • 3.        Department of Gynecology, Obstetrics and Oncological Gynecology, Bytom, Medical University of Silesia       Corresponding author: Krystyna Stencel-Gabriel ul. Batorego 15 41-902 Bytom   Keywords: leukotriene E4, infants, allergy, urine.   Summary Objective LTE4 is the end point of cysLTs pathway and its only stable product. Its role was discussed in asthma and AEDS. We aimed to investigate the impact of genetic and environmental factors ( sex, maternal positive family atopy history, breastfeeding, passive smoking and pet exposure . 60 newborns ( including 30 boys were enrolled in the study. Each child was examined at 12 months and urine samples for urinary LTE4 measurement were collected. All samples were processed using ACETM Enzyme Immunoassay Kit ( Cayman Chemical, Ann Arbor, MI, USA . The mean level of urinary LTE4 at 12 months was 186,99 pg/ml ( median: 159,0; CI 95%: 157,79- 221,59 . The Shapiro- Wilk test showed that the distribution of the levels of urinary LTE4 were abnormal. 12- month- old girls had higher urinary LTE4 levels than boys ( mean: 270,50 vs. 193,55 , but maternal positive atopy history, pet exposure, tobacco smoking or length of breastfeeding had no impact on urinary LTE4 excretion. Conclusions In conclusion, most of genetic or environmental factors do not change levels of urinary LTE4 in infants.

  4. The stability of liquid-filled matrix ionization chamber electronic portal imaging devices for dosimetry purposes

    International Nuclear Information System (INIS)

    Louwe, R.J.W.; Tielenburg, R.; Ingen, K.M. van; Mijnheer, B.J.; Herk, M.B. van

    2004-01-01

    This study was performed to determine the stability of liquid-filled matrix ionization chamber (LiFi-type) electronic portal imaging devices (EPID) for dosimetric purposes. The short- and long-term stability of the response was investigated, as well as the importance of factors influencing the response (e.g., temperature fluctuations, radiation damage, and the performance of the electronic hardware). It was shown that testing the performance of the electronic hardware as well as the short-term stability of the imagers may reveal the cause of a poor long-term stability of the imager response. In addition, the short-term stability was measured to verify the validity of the fitted dose-response curve immediately after beam startup. The long-term stability of these imagers could be considerably improved by correcting for room temperature fluctuations and gradual changes in response due to radiation damage. As a result, the reproducibility was better than 1% (1 SD) over a period of two years. The results of this study were used to formulate recommendations for a quality control program for portal dosimetry. The effect of such a program was assessed by comparing the results of portal dosimetry and in vivo dosimetry using diodes during the treatment of 31 prostate patients. The improvement of the results for portal dosimetry was consistent with the deviations observed with the reproducibility tests in that particular period. After a correction for the variation in response of the imager, the average difference between the measured and prescribed dose during the treatment of prostate patients was -0.7%±1.5% (1 SD), and -0.6%±1.1% (1 SD) for EPID and diode in vivo dosimetry, respectively. It can be concluded that a high stability of the response can be achieved for this type of EPID by applying a rigorous quality control program

  5. Imaging transient blood vessel fusion events in zebrafish by correlative volume electron microscopy.

    Directory of Open Access Journals (Sweden)

    Hannah E J Armer

    Full Text Available The study of biological processes has become increasingly reliant on obtaining high-resolution spatial and temporal data through imaging techniques. As researchers demand molecular resolution of cellular events in the context of whole organisms, correlation of non-invasive live-organism imaging with electron microscopy in complex three-dimensional samples becomes critical. The developing blood vessels of vertebrates form a highly complex network which cannot be imaged at high resolution using traditional methods. Here we show that the point of fusion between growing blood vessels of transgenic zebrafish, identified in live confocal microscopy, can subsequently be traced through the structure of the organism using Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM and Serial Block Face/Scanning Electron Microscopy (SBF/SEM. The resulting data give unprecedented microanatomical detail of the zebrafish and, for the first time, allow visualization of the ultrastructure of a time-limited biological event within the context of a whole organism.

  6. Study of imaging plate detector sensitivity to 5-18 MeV electrons

    Energy Technology Data Exchange (ETDEWEB)

    Boutoux, G., E-mail: boutoux@celia.u-bordeaux1.fr; Rabhi, N.; Batani, D.; Ducret, J.-E. [Univ. de Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence (France); Binet, A.; Nègre, J.-P.; Reverdin, C.; Thfoin, I. [CEA DAM DIF, F-91297 Arpajon (France); Jakubowska, K. [Institute of Plasma Physics and Laser Microfusion, Hery Street 23, 01-497 Warsaw (Poland)

    2015-11-15

    Imaging plates (IPs) are commonly used as passive detectors in laser-plasma experiments. We calibrated at the ELSA electron beam facility (CEA DIF) the five different available types of IPs (namely, MS-SR-TR-MP-ND) to electrons from 5 to 18 MeV. In the context of diagnostic development for the PETawatt Aquitaine Laser (PETAL), we investigated the use of stacks of IP in order to increase the detection efficiency and get detection response independent from the neighboring materials such as X-ray shielding and detector supports. We also measured fading functions in the time range from a few minutes up to a few days. Finally, our results are systematically compared to GEANT4 simulations in order to provide a complete study of the IP response to electrons over the energy range relevant for PETAL experiments.

  7. Imaging Plasmon Hybridization of Fano Resonances via Hot-Electron-Mediated Absorption Mapping.

    Science.gov (United States)

    Simoncelli, Sabrina; Li, Yi; Cortés, Emiliano; Maier, Stefan A

    2018-05-04

    The inhibition of radiative losses in dark plasmon modes allows storing electromagnetic energy more efficiently than in far-field excitable bright-plasmon modes. As such, processes benefiting from the enhanced absorption of light in plasmonic materials could also take profit of dark plasmon modes to boost and control nanoscale energy collection, storage, and transfer. We experimentally probe this process by imaging with nanoscale precision the hot-electron driven desorption of thiolated molecules from the surface of gold Fano nanostructures, investigating the effect of wavelength and polarization of the incident light. Spatially resolved absorption maps allow us to show the contribution of each element of the nanoantenna in the hot-electron driven process and their interplay in exciting a dark plasmon mode. Plasmon-mode engineering allows control of nanoscale reactivity and offers a route to further enhance and manipulate hot-electron driven chemical reactions and energy-conversion and transfer at the nanoscale.

  8. EPR and DNP Properties of Certain Novel Single Electron Contrast Agents Intended for Oximetric Imaging

    DEFF Research Database (Denmark)

    Ardenkjær-Larsen, J. H.; Laursen, I; Leunbach, I.

    1998-01-01

    Parameters of relevance to oximetry with Overhauser magnetic resonance imaging (OMRI) have been measured for three single electron contrast agents of the triphenylmethyl type. The single electron contrast agents are stable and water soluble. Magnetic resonance properties of the agents have been...... examined with electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and dynamic nuclear polarization (DNP) at 9.5 mT in water, isotonic saline, plasma, and blood at 23 and 37°C. The relaxivities of the agents are about 0.2–0.4 mM−1s−1and the DNP enhancements extrapolate close...... to the dipolar limit. The agents have a single, narrow EPR line, which is analyzed as a Voigt function. The linewidth is measured as a function of the agent concentration and the oxygen concentration. The concentration broadenings are about 1–3 μT/mM and the Lorentzian linewidths at infinite dilution are less...

  9. Position sensitive detector with semiconductor and image electron tube comprising such a detector

    International Nuclear Information System (INIS)

    Roziere, Guy.

    1977-01-01

    This invention concerns a position sensitive detector comprising a semiconducting substrate. It also concerns the electron tubes in which the detector may be incorporated in order to obtain an image formed at the tube input by an incident flux of particles or radiation. When a charged particle or group of such particles, electrons in particular, enter the space charge region of an inversely biased semiconductor diode, the energy supplied by these particles releases in the diode a certain number of electron-hole pairs which move in the field existing in the area towards the diode contacts. A corresponding current arises in the connections of this diode which constitutes the signal corresponding to the incident energy. Such a tube or chain of tubes is employed in nuclear medicine for observing parts of the human body, particularly by gamma radiation [fr

  10. Automated detection of a prostate Ni-Ti stent in electronic portal images.

    Science.gov (United States)

    Carl, Jesper; Nielsen, Henning; Nielsen, Jane; Lund, Bente; Larsen, Erik Hoejkjaer

    2006-12-01

    Planning target volumes (PTV) in fractionated radiotherapy still have to be outlined with wide margins to the clinical target volume due to uncertainties arising from daily shift of the prostate position. A recently proposed new method of visualization of the prostate is based on insertion of a thermo-expandable Ni-Ti stent. The current study proposes a new detection algorithm for automated detection of the Ni-Ti stent in electronic portal images. The algorithm is based on the Ni-Ti stent having a cylindrical shape with a fixed diameter, which was used as the basis for an automated detection algorithm. The automated method uses enhancement of lines combined with a grayscale morphology operation that looks for enhanced pixels separated with a distance similar to the diameter of the stent. The images in this study are all from prostate cancer patients treated with radiotherapy in a previous study. Images of a stent inserted in a humanoid phantom demonstrated a localization accuracy of 0.4-0.7 mm which equals the pixel size in the image. The automated detection of the stent was compared to manual detection in 71 pairs of orthogonal images taken in nine patients. The algorithm was successful in 67 of 71 pairs of images. The method is fast, has a high success rate, good accuracy, and has a potential for unsupervised localization of the prostate before radiotherapy, which would enable automated repositioning before treatment and allow for the use of very tight PTV margins.

  11. Automated detection of a prostate Ni-Ti stent in electronic portal images

    International Nuclear Information System (INIS)

    Carl, Jesper; Nielsen, Henning; Nielsen, Jane; Lund, Bente; Larsen, Erik Hoejkjaer

    2006-01-01

    Planning target volumes (PTV) in fractionated radiotherapy still have to be outlined with wide margins to the clinical target volume due to uncertainties arising from daily shift of the prostate position. A recently proposed new method of visualization of the prostate is based on insertion of a thermo-expandable Ni-Ti stent. The current study proposes a new detection algorithm for automated detection of the Ni-Ti stent in electronic portal images. The algorithm is based on the Ni-Ti stent having a cylindrical shape with a fixed diameter, which was used as the basis for an automated detection algorithm. The automated method uses enhancement of lines combined with a grayscale morphology operation that looks for enhanced pixels separated with a distance similar to the diameter of the stent. The images in this study are all from prostate cancer patients treated with radiotherapy in a previous study. Images of a stent inserted in a humanoid phantom demonstrated a localization accuracy of 0.4-0.7 mm which equals the pixel size in the image. The automated detection of the stent was compared to manual detection in 71 pairs of orthogonal images taken in nine patients. The algorithm was successful in 67 of 71 pairs of images. The method is fast, has a high success rate, good accuracy, and has a potential for unsupervised localization of the prostate before radiotherapy, which would enable automated repositioning before treatment and allow for the use of very tight PTV margins

  12. Pictorial review: Electron beam computed tomography and multislice spiral computed tomography for cardiac imaging

    International Nuclear Information System (INIS)

    Lembcke, Alexander; Hein, Patrick A.; Dohmen, Pascal M.; Klessen, Christian; Wiese, Till H.; Hoffmann, Udo; Hamm, Bernd; Enzweiler, Christian N.H.

    2006-01-01

    Electron beam computed tomography (EBCT) revolutionized cardiac imaging by combining a constant high temporal resolution with prospective ECG triggering. For years, EBCT was the primary technique for some non-invasive diagnostic cardiac procedures such as calcium scoring and non-invasive angiography of the coronary arteries. Multislice spiral computed tomography (MSCT) on the other hand significantly advanced cardiac imaging through high volume coverage, improved spatial resolution and retrospective ECG gating. This pictorial review will illustrate the basic differences between both modalities with special emphasis to their image quality. Several experimental and clinical examples demonstrate the strengths and limitations of both imaging modalities in an intraindividual comparison for a broad range of diagnostic applications such as coronary artery calcium scoring, coronary angiography including stent visualization as well as functional assessment of the cardiac ventricles and valves. In general, our examples indicate that EBCT suffers from a number of shortcomings such as limited spatial resolution and a low contrast-to-noise ratio. Thus, EBCT should now only be used in selected cases where a constant high temporal resolution is a crucial issue, such as dynamic (cine) imaging. Due to isotropic submillimeter spatial resolution and retrospective data selection MSCT seems to be the non-invasive method of choice for cardiac imaging in general, and for assessment of the coronary arteries in particular. However, technical developments are still needed to further improve the temporal resolution in MSCT and to reduce the substantial radiation exposure

  13. Verification of patient position and delivery of IMRT by electronic portal imaging

    International Nuclear Information System (INIS)

    Fielding, Andrew L.; Evans, Philip M.; Clark, Catharine H.

    2004-01-01

    Background and purpose: The purpose of the work presented in this paper was to determine whether patient positioning and delivery errors could be detected using electronic portal images of intensity modulated radiotherapy (IMRT). Patients and methods: We carried out a series of controlled experiments delivering an IMRT beam to a humanoid phantom using both the dynamic and multiple static field method of delivery. The beams were imaged, the images calibrated to remove the IMRT fluence variation and then compared with calibrated images of the reference beams without any delivery or position errors. The first set of experiments involved translating the position of the phantom both laterally and in a superior/inferior direction a distance of 1, 2, 5 and 10 mm. The phantom was also rotated 1 and 2 deg. For the second set of measurements the phantom position was kept fixed and delivery errors were introduced to the beam. The delivery errors took the form of leaf position and segment intensity errors. Results: The method was able to detect shifts in the phantom position of 1 mm, leaf position errors of 2 mm, and dosimetry errors of 10% on a single segment of a 15 segment IMRT step and shoot delivery (significantly less than 1% of the total dose). Conclusions: The results of this work have shown that the method of imaging the IMRT beam and calibrating the images to remove the intensity modulations could be a useful tool in verifying both the patient position and the delivery of the beam

  14. Observation of electron beam moiré fringes in an image conversion tube

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yunfei; Liao, Yubo [Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, Shenzhen University, Shenzhen 518060 (China); Long, Jing-hua [College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China); Cai, Houzhi; Bai, Yanli [Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, Shenzhen University, Shenzhen 518060 (China); Liu, Jinyuan, E-mail: ljy@szu.edu.cn [Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, Shenzhen University, Shenzhen 518060 (China)

    2016-11-15

    An image conversion tube with a magnetic lens was designed to observe electron beam moiré fringes. Electron beam moiré fringes result from the interference between the photocathode and the anode meshes. The photocathode had a strip line structure with a spatial frequency of 10 L/mm. The anode mesh had a fixed spatial frequency of 10 L/mm, and could be rotated around the axis of the image tube. The changes to the fringe direction and the spacing as a function of the rotation angle between the photocathode and the anode mesh were examined. The experimental results agreed with the theoretical analysis. Moiré fringes with a modulation of ~20% were obtained using a 3 keV electron beam. - Highlights: • Observe the electron beam moiré fringes in large angle of view. • The changes to the fringe direction and the spacing as a function of the rotation angle between the two gratings were examined. • Modulations of the moiré fringes in different rotation angle are recorded.

  15. Observation of electron beam moiré fringes in an image conversion tube

    International Nuclear Information System (INIS)

    Lei, Yunfei; Liao, Yubo; Long, Jing-hua; Cai, Houzhi; Bai, Yanli; Liu, Jinyuan

    2016-01-01

    An image conversion tube with a magnetic lens was designed to observe electron beam moiré fringes. Electron beam moiré fringes result from the interference between the photocathode and the anode meshes. The photocathode had a strip line structure with a spatial frequency of 10 L/mm. The anode mesh had a fixed spatial frequency of 10 L/mm, and could be rotated around the axis of the image tube. The changes to the fringe direction and the spacing as a function of the rotation angle between the photocathode and the anode mesh were examined. The experimental results agreed with the theoretical analysis. Moiré fringes with a modulation of ~20% were obtained using a 3 keV electron beam. - Highlights: • Observe the electron beam moiré fringes in large angle of view. • The changes to the fringe direction and the spacing as a function of the rotation angle between the two gratings were examined. • Modulations of the moiré fringes in different rotation angle are recorded.

  16. Refinement procedure for the image alignment in high-resolution electron tomography.

    Science.gov (United States)

    Houben, L; Bar Sadan, M

    2011-01-01

    High-resolution electron tomography from a tilt series of transmission electron microscopy images requires an accurate image alignment procedure in order to maximise the resolution of the tomogram. This is the case in particular for ultra-high resolution where even very small misalignments between individual images can dramatically reduce the fidelity of the resultant reconstruction. A tomographic-reconstruction based and marker-free method is proposed, which uses an iterative optimisation of the tomogram resolution. The method utilises a search algorithm that maximises the contrast in tomogram sub-volumes. Unlike conventional cross-correlation analysis it provides the required correlation over a large tilt angle separation and guarantees a consistent alignment of images for the full range of object tilt angles. An assessment based on experimental reconstructions shows that the marker-free procedure is competitive to the reference of marker-based procedures at lower resolution and yields sub-pixel accuracy even for simulated high-resolution data. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Excitation and characterization of image potential state electrons on quasi-free-standing graphene

    Science.gov (United States)

    Lin, Yi; Li, Yunzhe; Sadowski, Jerzy T.; Jin, Wencan; Dadap, Jerry I.; Hybertsen, Mark S.; Osgood, Richard M.

    2018-04-01

    We investigate the band structure of image potential states in quasi-free-standing graphene (QFG) monolayer islands using angle-resolved two-photon-photoemission spectroscopy. Direct probing by low-energy electron diffraction shows that QFG is formed following oxygen intercalation into the graphene-Ir(111) interface. Despite the apparent decoupling of the monolayer graphene from the Ir substrate, we find that the binding energy of the n =1 image potential state on these QFG islands increases by 0.17 eV, as compared to the original Gr/Ir(111) interface. We use calculations based on density-functional theory to construct an empirical, one-dimensional potential that quantitatively reproduces the image potential state binding energy and links the changes in the interface structure to the shift in energy. Specifically, two factors contribute comparably to this energy shift: a deeper potential well arising from the presence of intercalated oxygen adatoms and a wider potential well associated with the increase in the graphene-Ir distance. While image potential states have not been observed previously on QFG by photoemission, our paper now demonstrates that they may be strongly excited in a well-defined QFG system produced by oxygen intercalation. This opens an opportunity for studying the surface electron dynamics in QFG systems, beyond those found in typical nonintercalated graphene-on-substrate systems.

  18. A methodology for the extraction of quantitative information from electron microscopy images at the atomic level

    International Nuclear Information System (INIS)

    Galindo, P L; Pizarro, J; Guerrero, E; Guerrero-Lebrero, M P; Scavello, G; Yáñez, A; Sales, D L; Herrera, M; Molina, S I; Núñez-Moraleda, B M; Maestre, J M

    2014-01-01

    In this paper we describe a methodology developed at the University of Cadiz (Spain) in the past few years for the extraction of quantitative information from electron microscopy images at the atomic level. This work is based on a coordinated and synergic activity of several research groups that have been working together over the last decade in two different and complementary fields: Materials Science and Computer Science. The aim of our joint research has been to develop innovative high-performance computing techniques and simulation methods in order to address computationally challenging problems in the analysis, modelling and simulation of materials at the atomic scale, providing significant advances with respect to existing techniques. The methodology involves several fundamental areas of research including the analysis of high resolution electron microscopy images, materials modelling, image simulation and 3D reconstruction using quantitative information from experimental images. These techniques for the analysis, modelling and simulation allow optimizing the control and functionality of devices developed using materials under study, and have been tested using data obtained from experimental samples

  19. Theoretical and experimental study of image formation in scanning transmission electron microscopy

    International Nuclear Information System (INIS)

    Prunier epouse Mory, Claudie

    1985-01-01

    This thesis contains a theoretical and experimental study of image formation in a dedicated scanning transmission electron microscope (STEM). Using a detailed description of the different optical elements between the field emission source and the specimen, one calculates the shape and size of the primary probe of electrons impinging on the sample. This modelization enables to estimate the spatial resolution in the different imaging or microanalytical modes. The influence of the specimen and the role of the various detectors are taken into account to calculate the point spread function of the instrument in STEM imaging modes. An experimental study of the characteristic properties of phase contrast bright field micrographs and incoherent dark field ones is performed by comparison of digitally recorded images in similar conditions. Spatial resolution, contrast and signal/noise ratio are assessed by correlation methods, Fourier analysis and statistical considerations; one can deduce the optimum focusing conditions. Limits such as the point resolution on quasi-atomic metallic clusters are determined and an analysis of the capabilities of signal mixing concludes this work. Applications are offered in various domains such as the visualisation of small metallic particles, biomolecules and unstained biological sections. (author) [fr

  20. In vivo imaging of a stable paramagnetic probe by pulsed-radiofrequency electron paramagnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Murugesan; Cook; Devasahayam

    1997-01-01

    , Recent advances in radiofrequency (RF) electronics have enabled the generation of pulses of the order of 10-50 ns. Such short pulses provide adequate spectral coverage for EPR studies at 300 MHz resonant frequency. Acquisition of free induction decays (FID) of paramagnetic species possessing...... inhomogeneously broadened narrow lines after pulsed excitation is feasible with an appropriate digitizer/averager. This report describes the use of time-domain RF EPR spectrometry and imaging for in vivo applications. FID responses were collected from a water-soluble, narrow line width spin probe within phantom...... samples in solution and also when infused intravenously in an anesthetized mouse. Using static magnetic field gradients and back-projection methods of image reconstruction, two-dimensional images of the spin-probe distribution were obtained in phantom samples as well as in a mouse. The resolution...

  1. Imaging of surface spin textures on bulk crystals by scanning electron microscopy

    Science.gov (United States)

    Akamine, Hiroshi; Okumura, So; Farjami, Sahar; Murakami, Yasukazu; Nishida, Minoru

    2016-11-01

    Direct observation of magnetic microstructures is vital for advancing spintronics and other technologies. Here we report a method for imaging surface domain structures on bulk samples by scanning electron microscopy (SEM). Complex magnetic domains, referred to as the maze state in CoPt/FePt alloys, were observed at a spatial resolution of less than 100 nm by using an in-lens annular detector. The method allows for imaging almost all the domain walls in the mazy structure, whereas the visualisation of the domain walls with the classical SEM method was limited. Our method provides a simple way to analyse surface domain structures in the bulk state that can be used in combination with SEM functions such as orientation or composition analysis. Thus, the method extends applications of SEM-based magnetic imaging, and is promising for resolving various problems at the forefront of fields including physics, magnetics, materials science, engineering, and chemistry.

  2. Image-based electronic patient records for secured collaborative medical applications.

    Science.gov (United States)

    Zhang, Jianguo; Sun, Jianyong; Yang, Yuanyuan; Liang, Chenwen; Yao, Yihong; Cai, Weihua; Jin, Jin; Zhang, Guozhen; Sun, Kun

    2005-01-01

    We developed a Web-based system to interactively display image-based electronic patient records (EPR) for secured intranet and Internet collaborative medical applications. The system consists of four major components: EPR DICOM gateway (EPR-GW), Image-based EPR repository server (EPR-Server), Web Server and EPR DICOM viewer (EPR-Viewer). In the EPR-GW and EPR-Viewer, the security modules of Digital Signature and Authentication are integrated to perform the security processing on the EPR data with integrity and authenticity. The privacy of EPR in data communication and exchanging is provided by SSL/TLS-based secure communication. This presentation gave a new approach to create and manage image-based EPR from actual patient records, and also presented a way to use Web technology and DICOM standard to build an open architecture for collaborative medical applications.

  3. Phase-selective staining of metal salt for scanning electron microscopy imaging of block copolymer film

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jing Ze, E-mail: Lijinge@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Microelectronic and Solid-state Electronic, University of Electronic Science and Technology of China, Chengdu 610054 (China); State Key Laboratory of Polymer Materials Engineering (Sichuan University), Chengdu 610054 (China); Xinjiang Key Laboratory of Electronic Information Materials and Devices, Urumuqi 830011 (China); Wang, Ying; Hong Wang, Zhi; Mei, Di; Zou, Wei [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Microelectronic and Solid-state Electronic, University of Electronic Science and Technology of China, Chengdu 610054 (China); Min Chang, Ai [State Key Laboratory of Polymer Materials Engineering (Sichuan University), Chengdu 610054 (China); Wang, Qi [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Urumuqi 830011 (China); Komura, Motonori; Ito, Kaori [Division of Integrated Molecular Engineering, Chemical Resources Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Iyoda, Tomokazu, E-mail: Iyoda.t.aa@m.titech.ac.jp [Division of Integrated Molecular Engineering, Chemical Resources Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan)

    2010-09-15

    Three metal salts, i.e., AgNO{sub 3}, HAuCl{sub 4}, and KCl, were proposed as novel staining reagents instead of traditional RuO{sub 4} and OsO{sub 4} labeled with expensive price and extreme toxicity for scanning electron microscopy (SEM) imaging of microphase separated block copolymer film. A simple and costless aqueous solution immersion procedure could ensure selective staining of the metal slat in specific phase of the nanostructured copolymer film, leading to a clear phase contrasted SEM image. The heavy metal salt has better staining effect, demonstrating stable and high signal-to-noise SEM image even at an acceleration voltage as high as 30 kV and magnification up to 250,000 times.

  4. Electron Paramagnetic Resonance Spectrometry and Imaging in Melanomas: Comparison between Pigmented and Nonpigmented Human Malignant Melanomas

    Directory of Open Access Journals (Sweden)

    Quentin Godechal

    2013-06-01

    Full Text Available It has been known for a long time that the melanin pigments present in normal skin, hair, and most of malignant melanomas can be detected by electron paramagnetic resonance (EPR spectrometry. In this study, we used EPR imaging as a tool to map the concentration of melanin inside ex vivo human pigmented and nonpigmented melanomas and correlated this cartography with anatomopathology. We obtained accurate mappings of the melanin inside pigmented human melanoma samples. The signal intensity observed on the EPR images correlated with the concentration of melanin within the tumors, visible on the histologic sections. In contrast, no EPR signal coming from melanin was observed from nonpigmented melanomas, therefore demonstrating the absence of EPR-detectable pigments inside these particular cases of skin cancer and the importance of pigmentation for further EPR imaging studies on melanoma.

  5. On the release of cppxfel for processing X-ray free-electron laser images.

    Science.gov (United States)

    Ginn, Helen Mary; Evans, Gwyndaf; Sauter, Nicholas K; Stuart, David Ian

    2016-06-01

    As serial femtosecond crystallography expands towards a variety of delivery methods, including chip-based methods, and smaller collected data sets, the requirement to optimize the data analysis to produce maximum structure quality is becoming increasingly pressing. Here cppxfel , a software package primarily written in C++, which showcases several data analysis techniques, is released. This software package presently indexes images using DIALS (diffraction integration for advanced light sources) and performs an initial orientation matrix refinement, followed by post-refinement of individual images against a reference data set. Cppxfel is released with the hope that the unique and useful elements of this package can be repurposed for existing software packages. However, as released, it produces high-quality crystal structures and is therefore likely to be also useful to experienced users of X-ray free-electron laser (XFEL) software who wish to maximize the information extracted from a limited number of XFEL images.

  6. Invited Review Article: Methods for imaging weak-phase objects in electron microscopy

    International Nuclear Information System (INIS)

    Glaeser, Robert M.

    2013-01-01

    Contrast has traditionally been produced in electron-microscopy of weak phase objects by simply defocusing the objective lens. There now is renewed interest, however, in using devices that apply a uniform quarter-wave phase shift to the scattered electrons relative to the unscattered beam, or that generate in-focus image contrast in some other way. Renewed activity in making an electron-optical equivalent of the familiar “phase-contrast” light microscope is based in part on the improved possibilities that are now available for device microfabrication. There is also a better understanding that it is important to take full advantage of contrast that can be had at low spatial frequency when imaging large, macromolecular objects. In addition, a number of conceptually new phase-plate designs have been proposed, thus increasing the number of options that are available for development. The advantages, disadvantages, and current status of each of these options is now compared and contrasted. Experimental results that are, indeed, superior to what can be accomplished with defocus-based phase contrast have been obtained recently with two different designs of phase-contrast aperture. Nevertheless, extensive work also has shown that fabrication of such devices is inconsistent, and that their working lifetime is short. The main limitation, in fact, appears to be electrostatic charging of any device that is placed into the electron diffraction pattern. The challenge in fabricating phase plates that are practical to use for routine work in electron microscopy thus may be more in the area of materials science than in the area of electron optics

  7. Absolute Calibration of Image Plate for electrons at energy between 100 keV and 4 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H; Back, N L; Eder, D C; Ping, Y; Song, P M; Throop, A

    2007-12-10

    The authors measured the absolute response of image plate (Fuji BAS SR2040) for electrons at energies between 100 keV to 4 MeV using an electron spectrometer. The electron source was produced from a short pulse laser irradiated on the solid density targets. This paper presents the calibration results of image plate Photon Stimulated Luminescence PSL per electrons at this energy range. The Monte Carlo radiation transport code MCNPX results are also presented for three representative incident angles onto the image plates and corresponding electron energies depositions at these angles. These provide a complete set of tools that allows extraction of the absolute calibration to other spectrometer setting at this electron energy range.

  8. Automated sub-5 nm image registration in integrated correlative fluorescence and electron microscopy using cathodoluminescence pointers

    Science.gov (United States)

    Haring, Martijn T.; Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Voortman, Lenard M.; Kruit, Pieter; Hoogenboom, Jacob P.

    2017-03-01

    In the biological sciences, data from fluorescence and electron microscopy is correlated to allow fluorescence biomolecule identification within the cellular ultrastructure and/or ultrastructural analysis following live-cell imaging. High-accuracy (sub-100 nm) image overlay requires the addition of fiducial markers, which makes overlay accuracy dependent on the number of fiducials present in the region of interest. Here, we report an automated method for light-electron image overlay at high accuracy, i.e. below 5 nm. Our method relies on direct visualization of the electron beam position in the fluorescence detection channel using cathodoluminescence pointers. We show that image overlay using cathodoluminescence pointers corrects for image distortions, is independent of user interpretation, and does not require fiducials, allowing image correlation with molecular precision anywhere on a sample.

  9. Verification of multileaf collimator leaf positions using an electronic portal imaging device

    International Nuclear Information System (INIS)

    Samant, Sanjiv S.; Zheng Wei; Parra, Nestor Andres; Chandler, Jason; Gopal, Arun; Wu Jian; Jain Jinesh; Zhu Yunping; Sontag, Marc

    2002-01-01

    An automated method is presented for determining individual leaf positions of the Siemens dual focus multileaf collimator (MLC) using the Siemens BEAMVIEW(PLUS) electronic portal imaging device (EPID). Leaf positions are computed with an error of 0.6 mm at one standard deviation (σ) using separate computations of pixel dimensions, image distortion, and radiation center. The pixel dimensions are calculated by superimposing the film image of a graticule with the corresponding EPID image. A spatial correction is used to compensate for the optical distortions of the EPID, reducing the mean distortion from 3.5 pixels (uncorrected) per localized x-ray marker to 2 pixels (1 mm) for a rigid rotation and 1 pixel for a third degree polynomial warp. A correction for a nonuniform dosimetric response across the field of view of the EPID images is not necessary due to the sharp intensity gradients across leaf edges. The radiation center, calculated from the average of the geometric centers of a square field at 0 deg. and 180 deg. collimator angles, is independent of graticule placement error. Its measured location on the EPID image was stable to within 1 pixel based on 3 weeks of repeated extensions/retractions of the EPID. The MLC leaf positions determined from the EPID images agreed to within a pixel of the corresponding values measured using film and ionization chamber. Several edge detection algorithms were tested: contour, Sobel, Roberts, Prewitt, Laplace, morphological, and Canny. These agreed with each other to within ≤1.2 pixels for the in-air EPID images. Using a test pattern, individual MLC leaves were found to be typically within 1 mm of the corresponding record-and-verify values, with a maximum difference of 1.8 mm, and standard deviations of <0.3 mm in the daily reproducibility. This method presents a fast, automatic, and accurate alternative to using film or a light field for the verification and calibration of the MLC

  10. TH-CD-202-01: BEST IN PHYSICS (JOINT IMAGING-THERAPY): Evaluation of the Use of Direct Electron Density CT Images in Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, T; Sun, B; Li, H; Mutic, S [Washington University School of Medicine, St. Louis, MO (United States); Mistry, N [Siemens Healthcare, Cary, NC (United States); Raupach, R; Huenemohr, N; Ritter [Siemens Healthcare GmbH, Forchheim, Bavaria (Germany)

    2016-06-15

    Purpose: The current standard for calculation of photon and electron dose requires conversion of Hounsfield Units (HU) to Electron Density (ED) by applying a calibration curve specifically constructed for the corresponding CT tube voltage. This practice limits the use of the CT scanner to a single tube voltage and hinders the freedom in the selection of optimal tube voltage for better image quality. The objective of this study is to report a prototype CT reconstruction algorithm that provides direct ED images from the raw CT data independently of tube voltages used during acquisition. Methods: A tissue substitute phantom was scanned for Stoichiometric CT calibrations at tube voltages of 70kV, 80kV, 100kV, 120kV and 140kV respectively. HU images and direct ED images were acquired sequentially on a thoracic anthropomorphic phantom at the same tube voltages. Electron densities converted from the HU images were compared to ED obtained from the direct ED images. A 7-field treatment plan was made on all HU and ED images. Gamma analysis was performed to demonstrate quantitatively dosimetric change from the two schemes in acquiring ED. Results: The average deviation of EDs obtained from the direct ED images was −1.5%±2.1% from the EDs from HU images with the corresponding CT calibration curves applied. Gamma analysis on dose calculated on the direct ED images and the HU images acquired at the same tube voltage indicated negligible difference with lowest passing rate at 99.9%. Conclusion: Direct ED images require no CT calibration while demonstrate equivalent dosimetry compared to that obtained from standard HU images. The ability of acquiring direct ED images simplifies the current practice at a safer level by eliminating CT calibration and HU conversion from commissioning and treatment planning respectively. Furthermore, it unlocks a wider range of tube voltages in CT scanner for better imaging quality while maintaining similar dosimetric accuracy.

  11. Imaging spin filter for electrons based on specular reflection from iridium (001)

    Energy Technology Data Exchange (ETDEWEB)

    Kutnyakhov, D.; Lushchyk, P. [Johannes Gutenberg-Universität, Institut für Physik, 55099 Mainz (Germany); Fognini, A.; Perriard, D. [Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich (Switzerland); Kolbe, M.; Medjanik, K.; Fedchenko, E.; Nepijko, S.A.; Elmers, H.J. [Johannes Gutenberg-Universität, Institut für Physik, 55099 Mainz (Germany); Salvatella, G.; Stieger, C.; Gort, R.; Bähler, T.; Michlmayer, T.; Acremann, Y.; Vaterlaus, A. [Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich (Switzerland); Giebels, F.; Gollisch, H.; Feder, R. [Universität Duisburg-Essen, Theoretische Festkörperphysik, 47057 Duisburg (Germany); Tusche, C. [Max Planck-Institut für Mikrostrukturphysik, 06120 Halle (Germany); and others

    2013-07-15

    As Stern–Gerlach type spin filters do not work with electrons, spin analysis of electron beams is accomplished by spin-dependent scattering processes based on spin–orbit or exchange interaction. Existing polarimeters are single-channel devices characterized by an inherently low figure of merit (FoM) of typically 10{sup −4}–10{sup −3}. This single-channel approach is not compatible with parallel imaging microscopes and also not with modern electron spectrometers that acquire a certain energy and angular interval simultaneously. We present a novel type of polarimeter that can transport a full image by making use of k-parallel conservation in low-energy electron diffraction. We studied specular reflection from Ir (001) because this spin-filter crystal provides a high analyzing power combined with a “lifetime” in UHV of a full day. One good working point is centered at 39 eV scattering energy with a broad maximum of 5 eV usable width. A second one at about 10 eV shows a narrower profile but much higher FoM. A relativistic layer-KKR SPLEED calculation shows good agreement with measurements. - Highlights: • Novel type of spin polarimeter can transport a full image by making use of k{sup →}{sub ||} conservation in LEED. • When combined with a hemispherical analyzer, it acquires a certain energy and angular interval simultaneously. • Ir (001) based spin-filter provides a high analyzing power combined with a “lifetime” in UHV of a full day. • Parallel spin detection improves spin polarimeter efficiency by orders of magnitude. • A relativistic layer-KKR SPLEED calculation shows good agreement with measurements.

  12. Low magnification differential phase contrast imaging of electric fields in crystals with fine electron probes

    Energy Technology Data Exchange (ETDEWEB)

    Taplin, D.J. [School of Physics and Astronomy, Monash University, Clayton, Victoria 3800 (Australia); Shibata, N. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Weyland, M. [Monash Centre for Electron Microscopy, Monash University, Clayton, Victoria 3800 (Australia); Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800 (Australia); Findlay, S.D., E-mail: scott.findlay@monash.edu [School of Physics and Astronomy, Monash University, Clayton, Victoria 3800 (Australia)

    2016-10-15

    To correlate atomistic structure with longer range electric field distribution within materials, it is necessary to use atomically fine electron probes and specimens in on-axis orientation. However, electric field mapping via low magnification differential phase contrast imaging under these conditions raises challenges: electron scattering tends to reduce the beam deflection due to the electric field strength from what simple models predict, and other effects, most notably crystal mistilt, can lead to asymmetric intensity redistribution in the diffraction pattern which is difficult to distinguish from that produced by long range electric fields. Using electron scattering simulations, we explore the effects of such factors on the reliable interpretation and measurement of electric field distributions. In addition to these limitations of principle, some limitations of practice when seeking to perform such measurements using segmented detector systems are also discussed. - Highlights: • Measuring electric fields by on-axis electron diffraction is explored by simulation. • Electron channelling reduces deflection predicted by the phase object approximation. • First moment measurements cannot distinguish electric fields from specimen mistilt. • Segmented detector estimates are fairly insensitive to camera length and orientation.

  13. Automated determination of size and morphology information from soot transmission electron microscope (TEM)-generated images

    International Nuclear Information System (INIS)

    Wang, Cheng; Chan, Qing N.; Zhang, Renlin; Kook, Sanghoon; Hawkes, Evatt R.; Yeoh, Guan H.; Medwell, Paul R.

    2016-01-01

    The thermophoretic sampling of particulates from hot media, coupled with transmission electron microscope (TEM) imaging, is a combined approach that is widely used to derive morphological information. The identification and the measurement of the particulates, however, can be complex when the TEM images are of low contrast, noisy, and have non-uniform background signal level. The image processing method can also be challenging and time consuming, when the samples collected have large variability in shape and size, or have some degree of overlapping. In this work, a three-stage image processing sequence is presented to facilitate time-efficient automated identification and measurement of particulates from the TEM grids. The proposed processing sequence is first applied to soot samples that were thermophoretically sampled from a laminar non-premixed ethylene-air flame. The parameter values that are required to be set to facilitate the automated process are identified, and sensitivity of the results to these parameters is assessed. The same analysis process is also applied to soot samples that were acquired from an externally irradiated laminar non-premixed ethylene-air flame, which have different geometrical characteristics, to assess the morphological dependence of the proposed image processing sequence. Using the optimized parameter values, statistical assessments of the automated results reveal that the largest discrepancies that are associated with the estimated values of primary particle diameter, fractal dimension, and prefactor values of the aggregates for the tested cases, are approximately 3, 1, and 10 %, respectively, when compared with the manual measurements.

  14. The rapid secondary electron imaging system of the proton beam writer at CIBA

    International Nuclear Information System (INIS)

    Udalagama, C.N.B.; Bettiol, A.A.; Kan, J.A. van; Teo, E.J.; Watt, F.

    2007-01-01

    The recent years have witnessed a proliferation of research involving proton beam (p-beam) writing. This has prompted investigations into means of optimizing the process of p-beam writing so as to make it less time consuming and more efficient. One such avenue is the improvement of the pre-writing preparatory procedures that involves beam focusing and sample alignment which is centred on acquiring images of a resolution standard or sample. The conventional mode of imaging used up to now has utilized conventional nuclear microprobe signals that are of a pulsed nature and are inherently slow. In this work, we report the new imaging system that has been introduced, which uses proton induced secondary electrons. This in conjunction with software developed in-house that uses a National Instruments DAQ card with hardware triggering, facilitates large data transfer rates enabling rapid imaging. Frame rates as much as 10 frames/s have been achieved at an imaging resolution of 512 x 512 pixels

  15. Virus Particle Detection by Convolutional Neural Network in Transmission Electron Microscopy Images.

    Science.gov (United States)

    Ito, Eisuke; Sato, Takaaki; Sano, Daisuke; Utagawa, Etsuko; Kato, Tsuyoshi

    2018-06-01

    A new computational method for the detection of virus particles in transmission electron microscopy (TEM) images is presented. Our approach is to use a convolutional neural network that transforms a TEM image to a probabilistic map that indicates where virus particles exist in the image. Our proposed approach automatically and simultaneously learns both discriminative features and classifier for virus particle detection by machine learning, in contrast to existing methods that are based on handcrafted features that yield many false positives and require several postprocessing steps. The detection performance of the proposed method was assessed against a dataset of TEM images containing feline calicivirus particles and compared with several existing detection methods, and the state-of-the-art performance of the developed method for detecting virus was demonstrated. Since our method is based on supervised learning that requires both the input images and their corresponding annotations, it is basically used for detection of already-known viruses. However, the method is highly flexible, and the convolutional networks can adapt themselves to any virus particles by learning automatically from an annotated dataset.

  16. Automated determination of size and morphology information from soot transmission electron microscope (TEM)-generated images

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cheng; Chan, Qing N., E-mail: qing.chan@unsw.edu.au; Zhang, Renlin; Kook, Sanghoon; Hawkes, Evatt R.; Yeoh, Guan H. [UNSW, School of Mechanical and Manufacturing Engineering (Australia); Medwell, Paul R. [The University of Adelaide, Centre for Energy Technology (Australia)

    2016-05-15

    The thermophoretic sampling of particulates from hot media, coupled with transmission electron microscope (TEM) imaging, is a combined approach that is widely used to derive morphological information. The identification and the measurement of the particulates, however, can be complex when the TEM images are of low contrast, noisy, and have non-uniform background signal level. The image processing method can also be challenging and time consuming, when the samples collected have large variability in shape and size, or have some degree of overlapping. In this work, a three-stage image processing sequence is presented to facilitate time-efficient automated identification and measurement of particulates from the TEM grids. The proposed processing sequence is first applied to soot samples that were thermophoretically sampled from a laminar non-premixed ethylene-air flame. The parameter values that are required to be set to facilitate the automated process are identified, and sensitivity of the results to these parameters is assessed. The same analysis process is also applied to soot samples that were acquired from an externally irradiated laminar non-premixed ethylene-air flame, which have different geometrical characteristics, to assess the morphological dependence of the proposed image processing sequence. Using the optimized parameter values, statistical assessments of the automated results reveal that the largest discrepancies that are associated with the estimated values of primary particle diameter, fractal dimension, and prefactor values of the aggregates for the tested cases, are approximately 3, 1, and 10 %, respectively, when compared with the manual measurements.

  17. Experiments and Computational Theory for Electrical Breakdown in Critical Components: THz Imaging of Electronic Plasmas.

    Energy Technology Data Exchange (ETDEWEB)

    Zutavern, Fred J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hjalmarson, Harold P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bigman, Verle Howard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gallegos, Richard Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    This report describes the development of ultra-short pulse laser (USPL) induced terahertz (THz) radiation to image electronic plasmas during electrical breakdown. The technique uses three pulses from two USPLs to (1) trigger the breakdown, (2) create a 2 picosecond (ps, 10 -12 s), THz pulse to illuminate the breakdown, and (3) record the THz image of the breakdown. During this three year internal research program, sub-picosecond jitter timing for the lasers, THz generation, high bandwidth (BW) diagnostics, and THz image acquisition was demonstrated. High intensity THz radiation was optically-induced in a pulse-charged gallium arsenide photoconductive switch. The radiation was collected, transported, concentrated, and co-propagated through an electro-optic crystal with an 800 nm USPL pulse whose polarization was rotated due to the spatially varying electric field of the THz image. The polarization modulated USPL pulse was then passed through a polarizer and the resulting spatially varying intensity was detected in a high resolution digital camera. Single shot images had a signal to noise of %7E3:1. Signal to noise was improved to %7E30:1 with several experimental techniques and by averaging the THz images from %7E4000 laser pulses internally and externally with the camera and the acquisition system (40 pulses per readout). THz shadows of metallic films and objects were also recorded with this system to demonstrate free-carrier absorption of the THz radiation and improve image contrast and resolution. These 2 ps THz pulses were created and resolved with 100 femtosecond (fs, 10 -15 s) long USPL pulses. Thus this technology has the capability to time-resolve extremely fast repetitive or single shot phenomena, such as those that occur during the initiation of electrical breakdown. The goal of imaging electrical breakdown was not reached during this three year project. However, plans to achieve this goal as part of a follow-on project are described in this document

  18. Genetic influence of apolipoprotein E4 genotype on hippocampal morphometry: An N = 725 surface-based Alzheimer's disease neuroimaging initiative study.

    Science.gov (United States)

    Shi, Jie; Leporé, Natasha; Gutman, Boris A; Thompson, Paul M; Baxter, Leslie C; Caselli, Richard J; Wang, Yalin

    2014-08-01

    The apolipoprotein E (APOE) e4 allele is the most prevalent genetic risk factor for Alzheimer's disease (AD). Hippocampal volumes are generally smaller in AD patients carrying the e4 allele compared to e4 noncarriers. Here we examined the effect of APOE e4 on hippocampal morphometry in a large imaging database-the Alzheimer's Disease Neuroimaging Initiative (ADNI). We automatically segmented and constructed hippocampal surfaces from the baseline MR images of 725 subjects with known APOE genotype information including 167 with AD, 354 with mild cognitive impairment (MCI), and 204 normal controls. High-order correspondences between hippocampal surfaces were enforced across subjects with a novel inverse consistent surface fluid registration method. Multivariate statistics consisting of multivariate tensor-based morphometry (mTBM) and radial distance were computed for surface deformation analysis. Using Hotelling's T(2) test, we found significant morphological deformation in APOE e4 carriers relative to noncarriers in the entire cohort as well as in the nondemented (pooled MCI and control) subjects, affecting the left hippocampus more than the right, and this effect was more pronounced in e4 homozygotes than heterozygotes. Our findings are consistent with previous studies that showed e4 carriers exhibit accelerated hippocampal atrophy; we extend these findings to a novel measure of hippocampal morphometry. Hippocampal morphometry has significant potential as an imaging biomarker of early stage AD. Copyright © 2014 Wiley Periodicals, Inc.

  19. A workflow for the automatic segmentation of organelles in electron microscopy image stacks

    Science.gov (United States)

    Perez, Alex J.; Seyedhosseini, Mojtaba; Deerinck, Thomas J.; Bushong, Eric A.; Panda, Satchidananda; Tasdizen, Tolga; Ellisman, Mark H.

    2014-01-01

    Electron microscopy (EM) facilitates analysis of the form, distribution, and functional status of key organelle systems in various pathological processes, including those associated with neurodegenerative disease. Such EM data often provide important new insights into the underlying disease mechanisms. The development of more accurate and efficient methods to quantify changes in subcellular microanatomy has already proven key to understanding the pathogenesis of Parkinson's and Alzheimer's diseases, as well as glaucoma. While our ability to acquire large volumes of 3D EM data is progressing rapidly, more advanced analysis tools are needed to assist in measuring precise three-dimensional morphologies of organelles within data sets that can include hundreds to thousands of whole cells. Although new imaging instrument throughputs can exceed teravoxels of data per day, image segmentation and analysis remain significant bottlenecks to achieving quantitative descriptions of whole cell structural organellomes. Here, we present a novel method for the automatic segmentation of organelles in 3D EM image stacks. Segmentations are generated using only 2D image information, making the method suitable for anisotropic imaging techniques such as serial block-face scanning electron microscopy (SBEM). Additionally, no assumptions about 3D organelle morphology are made, ensuring the method can be easily expanded to any number of structurally and functionally diverse organelles. Following the presentation of our algorithm, we validate its performance by assessing the segmentation accuracy of different organelle targets in an example SBEM dataset and demonstrate that it can be efficiently parallelized on supercomputing resources, resulting in a dramatic reduction in runtime. PMID:25426032

  20. Electronically rotated and translated field-free line generation for open bore magnetic particle imaging.

    Science.gov (United States)

    Top, Can Barış; Ilbey, Serhat; Güven, Hüseyin Emre

    2017-12-01

    We propose a coil arrangement for open bore field-free line (FFL) magnetic particle imaging (MPI) system, which is suitable for accessing the subject from the sides. The purpose of this study is twofold, to show that the FFL can be rotated and translated electronically in a volume of interest with this arrangement and to analyze the current, voltage and power requirements for a 1 T/m gradient human sized scanner for a 200 mm diameter × 200 mm height cylindrical field of view (FOV). We used split coils side by side with alternating current directions to generate a field-free line. Employing two of these coil groups, one of which is rotated 90 degrees with respect to the other, a rotating FFL was generated. We conducted numerical simulations to show the feasibility of this arrangement for three-dimensional (3D) electronical scan of the FFL. Using simulations, we obtained images of a two-dimensional (2D) in silico dot phantom for a human size scanner with system matrix-based reconstruction. Simulations showed that the FFL can be generated and rotated in one plane and can be translated in two axes, allowing for 3D imaging of a large subject with the proposed arrangement. Human sized scanner required 63-215 kW power for the selection field coils to scan the focus inside the FOV. The proposed setup is suitable for FFL MPI imaging with an open bore configuration without the need for mechanical rotation, which is preferable for clinical usage in terms of imaging time and patient access. Further studies are necessary to determine the limitations imposed by peripheral nerve stimulation, and to optimize the system parameters and the sequence design. © 2017 American Association of Physicists in Medicine.

  1. An Evaluation of Dynamic Partial Reconfiguration for Signal and Image Processing in Professional Electronics Applications

    Directory of Open Access Journals (Sweden)

    Aulagnier Denis

    2008-01-01

    Full Text Available Abstract Signal and image processing applications require a lot of computing resources. For low-volume applications like in professional electronics applications, FPGA are used in combination with DSP and GPP in order to reach the performances required by the product roadmaps. Nevertheless, FPGA designs are static, which raises a flexibility issue with new complex or software defined applications like software-defined radio (SDR. In this scope, dynamic partial reconfiguration (DPR is used to bring a virtualization layer upon the static hardware of FPGA. During the last decade, DPR has been widely studied in academia. Nevertheless, there are very few real applications using it, and therefore, there is a lack of feedback providing relevant issues to address in order to improve its applicability. This paper evaluates the interest and limitations when using DPR in professional electronics applications and provides guidelines to improve its applicability. It makes a fair evaluation based on experiments made on a set of signal and image processing applications. It identifies the missing elements of the design flow to use DPR in professional electronics applications. Finally, it introduces a fast reconfiguration manager providing an 84-time improvement compared to the vendor solution.

  2. Global auroral conductance distribution due to electron and proton precipitation from IMAGE-FUV observations

    Directory of Open Access Journals (Sweden)

    V. Coumans

    2004-04-01

    Full Text Available The Far Ultraviolet (FUV imaging system on board the IMAGE satellite provides a global view of the north auroral region in three spectral channels, including the SI12 camera sensitive to Doppler shifted Lyman-α emission. FUV images are used to produce instantaneous maps of electron mean energy and energy fluxes for precipitated protons and electrons. We describe a method to calculate ionospheric Hall and Pedersen conductivities induced by auroral proton and electron ionization based on a model of interaction of auroral particles with the atmosphere. Different assumptions on the energy spectral distribution for electrons and protons are compared. Global maps of ionospheric conductances due to instantaneous observation of precipitating protons are calculated. The contribution of auroral protons in the total conductance induced by both types of auroral particles is also evaluated and the importance of proton precipitation is evaluated. This method is well adapted to analyze the time evolution of ionospheric conductances due to precipitating particles over the auroral region or in particular sectors. Results are illustrated with conductance maps of the north polar region obtained during four periods with different activity levels. It is found that the proton contribution to conductance is relatively higher during quiet periods than during substorms. The proton contribution is higher in the period before the onset and strongly decreases during the expansion phase of substorms. During a substorm which occurred on 28 April 2001, a region of strong proton precipitation is observed with SI12 around 14:00MLT at ~75° MLAT. Calculation of conductances in this sector shows that neglecting the protons contribution would produce a large error. We discuss possible effects of the proton precipitation on electron precipitation in auroral arcs. The increase in the ionospheric conductivity, induced by a former proton precipitation can reduce the potential drop

  3. Global auroral conductance distribution due to electron and proton precipitation from IMAGE-FUV observations

    Directory of Open Access Journals (Sweden)

    V. Coumans

    2004-04-01

    Full Text Available The Far Ultraviolet (FUV imaging system on board the IMAGE satellite provides a global view of the north auroral region in three spectral channels, including the SI12 camera sensitive to Doppler shifted Lyman-α emission. FUV images are used to produce instantaneous maps of electron mean energy and energy fluxes for precipitated protons and electrons. We describe a method to calculate ionospheric Hall and Pedersen conductivities induced by auroral proton and electron ionization based on a model of interaction of auroral particles with the atmosphere. Different assumptions on the energy spectral distribution for electrons and protons are compared. Global maps of ionospheric conductances due to instantaneous observation of precipitating protons are calculated. The contribution of auroral protons in the total conductance induced by both types of auroral particles is also evaluated and the importance of proton precipitation is evaluated. This method is well adapted to analyze the time evolution of ionospheric conductances due to precipitating particles over the auroral region or in particular sectors. Results are illustrated with conductance maps of the north polar region obtained during four periods with different activity levels. It is found that the proton contribution to conductance is relatively higher during quiet periods than during substorms. The proton contribution is higher in the period before the onset and strongly decreases during the expansion phase of substorms. During a substorm which occurred on 28 April 2001, a region of strong proton precipitation is observed with SI12 around 14:00MLT at ~75° MLAT. Calculation of conductances in this sector shows that neglecting the protons contribution would produce a large error. We discuss possible effects of the proton precipitation on electron precipitation in auroral arcs. The increase in the ionospheric conductivity, induced by a former proton precipitation can reduce the potential drop

  4. Monte Carlo simulation of secondary electron images for gold nanorods on the silicon substrate

    Science.gov (United States)

    Zhang, P.

    2018-06-01

    Recently, gold nanorods (Au NRs) have attracted much attention because at a particular photoelectricity the gold nanorods present a characteristic which is different from other types of Au nanomaterials with various shapes. Accurate measurement of aspect ratios does provide very high value of optical property for Au NRs. Monte Carlo (MC) simulation is thought of as the most accurate tool to perform size measurement through extracting structure parameters from the simulated scanning electron microscopy (SEM) image which best matches the experimental one. In this article, a series of MC-simulated secondary electron (SE) images have been taken for Au NRs on a silicon substrate. However, it has already been observed that the two ends of Au NRs in the experimental SEM image is brighter than that of the middle part. It seriously affects the accuracy of size measurement for Au NRs. The purpose of this work is to understand the mechanism underlying this phenomenon through a series of systematical analysis. It was found that the cetyltrimethylammonium bromide (CTAB) which covers the Au NRs indeed can alter the contrast of Au NRs compared to that without CTAB covering. However, SEs emitting from CTAB are not the reason for the abnormal brightness at the two ends of NRs. This work reveals that the charging effect might be the leading cause for this phenomenon.

  5. Electronic spreadsheet to acquire the reflectance from the TM and ETM+ Landsat images

    Directory of Open Access Journals (Sweden)

    Antonio R. Formaggio

    2005-08-01

    Full Text Available The reflectance of agricultural cultures and other terrestrial surface "targets" is an intrinsic parameter of these targets, so in many situations, it must be used instead of the values of "gray levels" that is found in the satellite images. In order to get reflectance values, it is necessary to eliminate the atmospheric interference and to make a set of calculations that uses sensor parameters and information regarding the original image. The automation of this procedure has the advantage to speed up the process and to reduce the possibility of errors during calculations. The objective of this paper is to present an electronic spreadsheet that simplifies and automatizes the transformation of the digital numbers of the TM/Landsat-5 and ETM+/Landsat-7 images into reflectance. The method employed for atmospheric correction was the dark object subtraction (DOS. The electronic spreadsheet described here is freely available to users and can be downloaded at the following website: http://www.dsr.inpe.br/Calculo_Reflectancia.xls.

  6. Miniature Variable Pressure Scanning Electron Microscope for In-Situ Imaging and Chemical Analysis

    Science.gov (United States)

    Gaskin, Jessica A.; Jerman, Gregory; Gregory, Don; Sampson, Allen R.

    2012-01-01

    NASA Marshall Space Flight Center (MSFC) is leading an effort to develop a Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) for in-situ imaging and chemical analysis of uncoated samples. This instrument development will be geared towards operation on Mars and builds on a previous MSFC design of a mini-SEM for the moon (funded through the NASA Planetary Instrument Definition and Development Program). Because Mars has a dramatically different environment than the moon, modifications to the MSFC lunar mini-SEM are necessary. Mainly, the higher atmospheric pressure calls for the use of an electron gun that can operate at High Vacuum, rather than Ultra-High Vacuum. The presence of a CO2-rich atmosphere also allows for the incorporation of a variable pressure system that enables the in-situ analysis of nonconductive geological specimens. Preliminary testing of Mars meteorites in a commercial Environmental SEM(Tradmark) (FEI) confirms the usefulness of lowcurrent/low-accelerating voltage imaging and highlights the advantages of using the Mars atmosphere for environmental imaging. The unique capabilities of the MVP-SEM make it an ideal tool for pursuing key scientific goals of NASA's Flagship Mission Max-C; to perform in-situ science and collect and cache samples in preparation for sample return from Mars.

  7. Assessment of Set-up Accuracy in Tangential Breast Treatment Using Electronic Portal Imaging Device

    International Nuclear Information System (INIS)

    Lee, Byung Koo; Kang, Soo Man

    2012-01-01

    The aim of this study was to investigate the setup accuracy for tangential breast treatment patients using electronic portal image and 2-D reconstruction image Twenty two patients undergoing tangential breast treatment. To explore the setup accuracy, distances between chosen landmarks were taken as reference parameters. The difference between measured reference parameters on simulation films and electronic portal images (EPIs) was calculated as the setup error. A total of 22 simulation films and 110 EPIs were evaluated. In the tangential fields, the calculated reference parameters were the central lung distance (CLD), central soft-tissue distance (CSTD), and above lung distance (ALD), below lung distance (BLD). In the medial tangential field, the average difference values for these parameters were 1.0, -6.4, -2.1 and 2.0, respectively; and the values were 1.5, 2.3, 4.1 and 1.1, respectively. In the lateral tangential field, the average difference values for these parameters were -1.5, -4.3, -2.7 and -1.3, respectively; and the values were 3.3, 2.1, 2.9 and 2.5, respectively. CLD, CSTD, ALD and BLD in the tangential fields are easily identifiable and are helpful for detecting setup errors using EPIs in patients undergoing tangential breast radiotherapy treatment.

  8. Assessment of Set-up Accuracy in Tangential Breast Treatment Using Electronic Portal Imaging Device

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byung Koo [Dept. of Radiation Oncology, Korea University Anam Hospital, Seoul (Korea, Republic of); Kang, Soo Man [Dept. of Radiation Oncology, Korea University Gospel Hospital, Seoul (Korea, Republic of)

    2012-09-15

    The aim of this study was to investigate the setup accuracy for tangential breast treatment patients using electronic portal image and 2-D reconstruction image Twenty two patients undergoing tangential breast treatment. To explore the setup accuracy, distances between chosen landmarks were taken as reference parameters. The difference between measured reference parameters on simulation films and electronic portal images (EPIs) was calculated as the setup error. A total of 22 simulation films and 110 EPIs were evaluated. In the tangential fields, the calculated reference parameters were the central lung distance (CLD), central soft-tissue distance (CSTD), and above lung distance (ALD), below lung distance (BLD). In the medial tangential field, the average difference values for these parameters were 1.0, -6.4, -2.1 and 2.0, respectively; and the values were 1.5, 2.3, 4.1 and 1.1, respectively. In the lateral tangential field, the average difference values for these parameters were -1.5, -4.3, -2.7 and -1.3, respectively; and the values were 3.3, 2.1, 2.9 and 2.5, respectively. CLD, CSTD, ALD and BLD in the tangential fields are easily identifiable and are helpful for detecting setup errors using EPIs in patients undergoing tangential breast radiotherapy treatment.

  9. Cherenkov imaging method for rapid optimization of clinical treatment geometry in total skin electron beam therapy

    Energy Technology Data Exchange (ETDEWEB)

    Andreozzi, Jacqueline M., E-mail: Jacqueline.M.Andreozzi.th@dartmouth.edu, E-mail: Lesley.A.Jarvis@hitchcock.org; Glaser, Adam K. [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States); Zhang, Rongxiao [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Gladstone, David J.; Williams, Benjamin B.; Jarvis, Lesley A., E-mail: Jacqueline.M.Andreozzi.th@dartmouth.edu, E-mail: Lesley.A.Jarvis@hitchcock.org [Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766 (United States); Pogue, Brian W. [Thayer School of Engineering and Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States)

    2016-02-15

    Purpose: A method was developed utilizing Cherenkov imaging for rapid and thorough determination of the two gantry angles that produce the most uniform treatment plane during dual-field total skin electron beam therapy (TSET). Methods: Cherenkov imaging was implemented to gather 2D measurements of relative surface dose from 6 MeV electron beams on a white polyethylene sheet. An intensified charge-coupled device camera time-gated to the Linac was used for Cherenkov emission imaging at sixty-two different gantry angles (1° increments, from 239.5° to 300.5°). Following a modified Stanford TSET technique, which uses two fields per patient position for full body coverage, composite images were created as the sum of two beam images on the sheet; each angle pair was evaluated for minimum variation across the patient region of interest. Cherenkov versus dose correlation was verified with ionization chamber measurements. The process was repeated at source to surface distance (SSD) = 441, 370.5, and 300 cm to determine optimal angle spread for varying room geometries. In addition, three patients receiving TSET using a modified Stanford six-dual field technique with 6 MeV electron beams at SSD = 441 cm were imaged during treatment. Results: As in previous studies, Cherenkov intensity was shown to directly correlate with dose for homogenous flat phantoms (R{sup 2} = 0.93), making Cherenkov imaging an appropriate candidate to assess and optimize TSET setup geometry. This method provided dense 2D images allowing 1891 possible treatment geometries to be comprehensively analyzed from one data set of 62 single images. Gantry angles historically used for TSET at their institution were 255.5° and 284.5° at SSD = 441 cm; however, the angles optimized for maximum homogeneity were found to be 252.5° and 287.5° (+6° increase in angle spread). Ionization chamber measurements confirmed improvement in dose homogeneity across the treatment field from a range of 24.4% at the initial

  10. Determination of the cork bark porosity through the gamma ray transmission technology and electronic scanning microscopy image analysis

    International Nuclear Information System (INIS)

    Moraes, Antonio M.C.; Moreira, Anderson C.; Appoloni, Carlos R.

    2007-01-01

    This work applies the gamma transmission techniques (GTR) and imaging by scanning electron microscopy (SEM) for determination of porosity in the sparkling wine bottle corks. The gamma transmission experimental apparatus consists of a micrometric table (ZX) of sample movement automated, a Am-241 source (59,53 keV, 100 mCi), lead collimators, sample-holder, Na I(Tl) detector and appropriated electronics. For the microscopic images an FEI (Quanta 200), electronic microscope with associated electronics was used, and the image analysis was performed with IMAGO software. The average porosity for 22 samples analysed by GTR was of φ=58 +- 4.6 percent. By the imaging technique the found average porosity was φ=60.0 +- 6.2 percent. (author)

  11. Treatment verification with megavoltage electronic portal imaging applied to the tomotherapy concept

    International Nuclear Information System (INIS)

    Hesse, B.-M.; Spies, L.; Groh, B.; Doll, J.; Haering, P.; Hoever, K. H.

    1997-01-01

    Purpose: A new treatment strategy called Tomotherapy, introduced by T. R. Mackie et al. in 1993, was designed to perform a dynamic conformal treatment technique in precision radiotherapy. This technique delivers sliced intensity-modulated radiation fields to achieve best tumor control while sparing neighbouring sensitive normal tissue and organs at risk. The beam continuously revolves around the patient similarly to a spiral-CT while the patient is moved through the bore of the gantry. As a first step towards the realization of such a concept with a linear accelerator (Siemens Mevatron Experimental) used in clinical routine, we focused on treatment setup and dose verification. In tomotherapy, an actual CT data set is needed for patient positioning and for the verification of the absorbed dose, also, the dose transmitted through the patient must be known. This makes possible both routine tomographic treatment setup verification and tomographic dose reconstruction of the actual delivered dose. Materials and Methods: All measurements were performed with a megavoltage electronic portal imaging device of Wellhoefer TM (BIS-710). The BIS-710 detector is based on a scintillation foil and contains a camera for 10-bit digital data output. The dimension of the detector plane is 512 x 512 pixels with a pixel size of 0.6 mm in each direction. The BIS-710 was developed especially for quantitative dose measuring, whereas most of the existing Portal Imaging Systems are used for image display only. To examine the properties of the BIS-710 concerning tomographical reconstruction with a therapeutic 6 MV X-ray beam, a tissue-equivalent Alderson head phantom was rotated stepwise across a stationary beam between the collimator and the detector plane. The influence of scattering can be estimated by comparing measurements which were taken with a homogeneous phantom which is invariant under rotation with a calculated exit dose distribution using a simple exponential law for the

  12. Using the Medipix3 detector for direct electron imaging in the range 60 keV to 200 keV in electron microscopy

    Science.gov (United States)

    Mir, J. A.; Plackett, R.; Shipsey, I.; dos Santos, J. M. F.

    2017-11-01

    Hybrid pixel sensor technology such as the Medipix3 represents a unique tool for electron imaging. We have investigated its performance as a direct imaging detector using a Transmission Electron Microscope (TEM) which incorporated a Medipix3 detector with a 300 μm thick silicon layer compromising of 256×256 pixels at 55 μm pixel pitch. We present results taken with the Medipix3 in Single Pixel Mode (SPM) with electron beam energies in the range, 60-200 keV . Measurements of the Modulation Transfer Function (MTF) and the Detective Quantum Efficiency (DQE) were investigated. At a given beam energy, the MTF data was acquired by deploying the established knife edge technique. Similarly, the experimental data required to determine DQE was obtained by acquiring a stack of images of a focused beam and of free space (flatfield) to determine the Noise Power Spectrum (NPS).

  13. Proposed alteration of images of molecular orbitals obtained using a scanning tunneling microscope as a probe of electron correlation.

    Science.gov (United States)

    Toroz, Dimitrios; Rontani, Massimo; Corni, Stefano

    2013-01-04

    Scanning tunneling spectroscopy (STS) allows us to image single molecules decoupled from the supporting substrate. The obtained images are routinely interpreted as the square moduli of molecular orbitals, dressed by the mean-field electron-electron interaction. Here we demonstrate that the effect of electron correlation beyond the mean field qualitatively alters the uncorrelated STS images. Our evidence is based on the ab initio many-body calculation of STS images of planar molecules with metal centers. We find that many-body correlations alter significantly the image spectral weight close to the metal center of the molecules. This change is large enough to be accessed experimentally, surviving to molecule-substrate interactions.

  14. Scanning Electron Microscope Calibration Using a Multi-Image Non-Linear Minimization Process

    Science.gov (United States)

    Cui, Le; Marchand, Éric

    2015-04-01

    A scanning electron microscope (SEM) calibrating approach based on non-linear minimization procedure is presented in this article. A part of this article has been published in IEEE International Conference on Robotics and Automation (ICRA), 2014. . Both the intrinsic parameters and the extrinsic parameters estimations are achieved simultaneously by minimizing the registration error. The proposed approach considers multi-images of a multi-scale calibration pattern view from different positions and orientations. Since the projection geometry of the scanning electron microscope is different from that of a classical optical sensor, the perspective projection model and the parallel projection model are considered and compared with distortion models. Experiments are realized by varying the position and the orientation of a multi-scale chessboard calibration pattern from 300× to 10,000×. The experimental results show the efficiency and the accuracy of this approach.

  15. Single-Molecule Imaging with X-Ray Free-Electron Lasers: Dream or Reality?

    KAUST Repository

    Fratalocchi, Andrea

    2011-03-09

    X-ray free-electron lasers (XFEL) are revolutionary photon sources, whose ultrashort, brilliant pulses are expected to allow single-molecule diffraction experiments providing structural information on the atomic length scale of nonperiodic objects. This ultimate goal, however, is currently hampered by several challenging questions basically concerning sample damage, Coulomb explosion, and the role of nonlinearity. By employing an original ab initio approach, we address these issues showing that XFEL-based single-molecule imaging will be only possible with a few-hundred long attosecond pulses, due to significant radiation damage and the formation of preferred multisoliton clusters which reshape the overall electronic density of the molecular system at the femtosecond scale.

  16. Single-Molecule Imaging with X-Ray Free-Electron Lasers: Dream or Reality?

    KAUST Repository

    Fratalocchi, Andrea; Ruocco, G.

    2011-01-01

    X-ray free-electron lasers (XFEL) are revolutionary photon sources, whose ultrashort, brilliant pulses are expected to allow single-molecule diffraction experiments providing structural information on the atomic length scale of nonperiodic objects. This ultimate goal, however, is currently hampered by several challenging questions basically concerning sample damage, Coulomb explosion, and the role of nonlinearity. By employing an original ab initio approach, we address these issues showing that XFEL-based single-molecule imaging will be only possible with a few-hundred long attosecond pulses, due to significant radiation damage and the formation of preferred multisoliton clusters which reshape the overall electronic density of the molecular system at the femtosecond scale.

  17. Development of CRID [Cerenkov Ring Imaging Detector] single electron wire detector

    International Nuclear Information System (INIS)

    Aston, D.; Bean, A.; Bienz, T.

    1989-02-01

    We describe the R and D effort to define the design parameters, method of construction and experimental results from the single electron wire detectors. These detectors will be used for particle identification using the Cerenkov Ring Imaging techniques in the SLD experiment at SLAC. We present measurements of pulse heights for several gases as a function of gas gain, charge division performance on a single electron signal using both 7 μm and 33 μm diameter carbon wires, photon feedback in TMAE laden gas, average pulse shape, and its comparison with the predicted shape and cross-talk. In addition, we present results of wire aging tests, and other tests associated with construction of this unusual type of wire chamber. 12 refs., 9 figs

  18. Synthesis of Specific Nanoparticles for Targeting and Imaging Tumor Angiogenesis Using Electron-Beam Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Rizza, G.; Deshayes, S.; Maurizot, V.; Clochard, M. -C.; Berthelot, T.; Baudin, C.; Déléris, G., E-mail: giancarlo.rizza@polytechnique.edu [Commissariat à l' énergie atomique (CEA), Institut Rayonnement Matière de Saclay (IRaMIS), B.P. 52, 91191 Gif Sur Yvette Cedex (France)

    2010-07-01

    We have succeeded to synthesize PVDF nanoparticles by nanoemulsion polymerization and their functionalization with a peptide that presents an anti-angiogenic activity. Resulted nanoparticles present a radius of 60 nm. From FESEM images and light scattering measurements, we deduced that they were spherical and monodisperse. The alkyl radicals induced from electron beam irradiation combine immediately with the oxygen to form peroxide radicals. Because of a high specific area and small crystallite size, the radical decay with time is evidenced from EPR measurements. Despite this radical decay, electron beam irradiation allows us to graft PAA by radical polymerization onto freshly irradiated PVDF nanoparticles and then to immobilize CBO-P11 by click chemistry via a spacer arm. Evidences of grafting were shown using HRMAS NMR and MALDI-TOF mass spectrometry. Nanoparticles functionalized with an angiogenesis-targeting agent are an attractive option for anti-tumor therapy.

  19. Aerosol Imaging with a Soft X-ray Free Electron Laser

    International Nuclear Information System (INIS)

    Bogan, Michael J.; Boutet, Sebastien; Chapman, Henry N.; Marchesini, Stefano; Barty, Anton; Benner, W. Henry; Rohner, Urs; Frank, Matthias; Hau-Riege, Stefan P.; Bajt, Sasa; Woods, Bruce; Seibert, M.M.; Iwan, Bianca; Timneanu, Nicusor; Hajdu, Janos; Schulz, Joachim

    2010-01-01

    Lasers have long played a critical role in the advancement of aerosol science. A new regime of ultrafast laser technology has recently be realized, the world's first soft xray free electron laser. The Free electron LASer in Hamburg, FLASH, user facility produces a steady source of 10 femtosecond pulses of 7-32 nm x-rays with 10 12 photons per pulse. The high brightness, short wavelength, and high repetition rate (>500 pulses per second) of this laser offers unique capabilities for aerosol characterization. Here we use FLASH to perform the highest resolution imaging of single PM2.5 aerosol particles in flight to date. We resolve to 35 nm the morphology of fibrous and aggregated spherical carbonaceous nanoparticles that existed for less than two milliseconds in vacuum. Our result opens the possibility for high spatialand time-resolved single particle aerosol dynamics studies, filling a critical technological need in aerosol science.

  20. Nanoparticle imaging. 3D structure of individual nanocrystals in solution by electron microscopy.

    Science.gov (United States)

    Park, Jungwon; Elmlund, Hans; Ercius, Peter; Yuk, Jong Min; Limmer, David T; Chen, Qian; Kim, Kwanpyo; Han, Sang Hoon; Weitz, David A; Zettl, A; Alivisatos, A Paul

    2015-07-17

    Knowledge about the synthesis, growth mechanisms, and physical properties of colloidal nanoparticles has been limited by technical impediments. We introduce a method for determining three-dimensional (3D) structures of individual nanoparticles in solution. We combine a graphene liquid cell, high-resolution transmission electron microscopy, a direct electron detector, and an algorithm for single-particle 3D reconstruction originally developed for analysis of biological molecules. This method yielded two 3D structures of individual platinum nanocrystals at near-atomic resolution. Because our method derives the 3D structure from images of individual nanoparticles rotating freely in solution, it enables the analysis of heterogeneous populations of potentially unordered nanoparticles that are synthesized in solution, thereby providing a means to understand the structure and stability of defects at the nanoscale. Copyright © 2015, American Association for the Advancement of Science.

  1. Synthesis of Specific Nanoparticles for Targeting and Imaging Tumor Angiogenesis Using Electron-Beam Irradiation

    International Nuclear Information System (INIS)

    Rizza, G.; Deshayes, S.; Maurizot, V.; Clochard, M.-C.; Berthelot, T.; Baudin, C.; Déléris, G.

    2010-01-01

    We have succeeded to synthesize PVDF nanoparticles by nanoemulsion polymerization and their functionalization with a peptide that presents an anti-angiogenic activity. Resulted nanoparticles present a radius of 60 nm. From FESEM images and light scattering measurements, we deduced that they were spherical and monodisperse. The alkyl radicals induced from electron beam irradiation combine immediately with the oxygen to form peroxide radicals. Because of a high specific area and small crystallite size, the radical decay with time is evidenced from EPR measurements. Despite this radical decay, electron beam irradiation allows us to graft PAA by radical polymerization onto freshly irradiated PVDF nanoparticles and then to immobilize CBO-P11 by click chemistry via a spacer arm. Evidences of grafting were shown using HRMAS NMR and MALDI-TOF mass spectrometry. Nanoparticles functionalized with an angiogenesis-targeting agent are an attractive option for anti-tumor therapy

  2. Efficient creation of electron vortex beams for high resolution STEM imaging.

    Science.gov (United States)

    Béché, A; Juchtmans, R; Verbeeck, J

    2017-07-01

    The recent discovery of electron vortex beams carrying quantised angular momentum in the TEM has led to an active field of research, exploring a variety of potential applications including the possibility of mapping magnetic states at the atomic scale. A prerequisite for this is the availability of atomic sized electron vortex beams at high beam current and mode purity. In this paper we present recent progress showing that by making use of the Aharonov-Bohm effect near the tip of a long single domain ferromagnetic Nickel needle, a very efficient aperture for the production of electron vortex beams can be realised. The aperture transmits more than 99% of all electrons and provides a vortex mode purity of up to 92%. Placing this aperture in the condenser plane of a state of the art Cs corrected microscope allows us to demonstrate atomic resolution HAADF STEM images with spatial resolution better than 1 Angström, in agreement with theoretical expectations and only slightly inferior to the performance of a non-vortex probe on the same instrument. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Backscattered electron imaging at low emerging angles: A physical approach to contrast in LVSEM

    Energy Technology Data Exchange (ETDEWEB)

    Cazaux, J., E-mail: jacques.cazaux@univ-reims.fr [LISM, EA 4695 Faculty of Sciences, BP 1039, 51687 Reims Cedex 2 (France); Kuwano, N. [Malaysia–Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur (Malaysia); Sato, K. [Steel Research Laboratory, JFE Steel Corporation, 1 Kawasaki-cho, Chuo-ku, Chiba 260-0835 (Japan)

    2013-12-15

    Due to the influence of refraction effects on the escape probability of the Back-Scattered Electrons (BSE), an expression of the fraction of these BSE is given as a function of the beam energy, E°, and emission angle (with respect to the normal) α. It has been shown that these effects are very sensitive to a local change of the work function in particular for low emerging angles. This sensitivity suggests a new type of contrast in Low Voltage Scanning Electron Microscopy (LVSEM for E°<2 keV): the work function contrast. Involving the change of ϕ with crystalline orientation, this possibility is supported by a new interpretation of a few published images. Some other correlated contrasts are also suggested. These are topographical contrasts or contrasts due to subsurface particles and cracks. Practical considerations of the detection system and its optimization are indicated. - Highlights: • Refraction effects experienced by Back-Scattered Electrons at sample/vacuum interfaces are evaluated as a function of energy and angles. • Sensitive to local work function changes with crystalline orientation these effects concern mainly keV-electrons at low emerging angles. • A new type of contrast in SEM is thus deduced and illustrated. • Some other correlated contrasts, topographical contrasts or contrasts due to subsurface particles and cracks are also suggested.

  4. Large area strain analysis using scanning transmission electron microscopy across multiple images

    International Nuclear Information System (INIS)

    Oni, A. A.; Sang, X.; LeBeau, J. M.; Raju, S. V.; Saxena, S.; Dumpala, S.; Broderick, S.; Rajan, K.; Kumar, A.; Sinnott, S.

    2015-01-01

    Here, we apply revolving scanning transmission electron microscopy to measure lattice strain across a sample using a single reference area. To do so, we remove image distortion introduced by sample drift, which usually restricts strain analysis to a single image. Overcoming this challenge, we show that it is possible to use strain reference areas elsewhere in the sample, thereby enabling reliable strain mapping across large areas. As a prototypical example, we determine the strain present within the microstructure of a Ni-based superalloy directly from atom column positions as well as geometric phase analysis. While maintaining atomic resolution, we quantify strain within nanoscale regions and demonstrate that large, unit-cell level strain fluctuations are present within the intermetallic phase

  5. Ralicon anodes for image photon counting fabricated by electron beam lithography

    International Nuclear Information System (INIS)

    Burton, W.M.

    1982-01-01

    The Anger wedge and strip anode event location system developed for microchannel plate image photon detectors at the Space Sciences Laboratory of the University of California, Berkeley, has been extended in the present work by the use of electron beam lithography (EBL). This method of fabrication can be used to produce optical patterns for the subsequent manufacture of anodes by conventional photo-etching methods and has also enabled anodes to be produced directly by EBL microfabrication techniques. Computer-aided design methods have been used to develop several types of RALICON (Readout Anodes of Lithographic Construction) for use in photon counting microchannel plate imaging detectors. These anodes are suitable for linear, two dimensional or radial position measurements and they incorporate novel design features made possible by the EBL fabrication technique which significantly extend their application relative to published wedge-strip anode designs. (author)

  6. Photon counting imaging and centroiding with an electron-bombarded CCD using single molecule localisation software

    International Nuclear Information System (INIS)

    Hirvonen, Liisa M.; Barber, Matthew J.; Suhling, Klaus

    2016-01-01

    Photon event centroiding in photon counting imaging and single-molecule localisation in super-resolution fluorescence microscopy share many traits. Although photon event centroiding has traditionally been performed with simple single-iteration algorithms, we recently reported that iterative fitting algorithms originally developed for single-molecule localisation fluorescence microscopy work very well when applied to centroiding photon events imaged with an MCP-intensified CMOS camera. Here, we have applied these algorithms for centroiding of photon events from an electron-bombarded CCD (EBCCD). We find that centroiding algorithms based on iterative fitting of the photon events yield excellent results and allow fitting of overlapping photon events, a feature not reported before and an important aspect to facilitate an increased count rate and shorter acquisition times.

  7. Automated detection of a prostate Ni-Ti stent in electronic portal images

    OpenAIRE

    Carl, Jesper; Nielsen, Henning; Nielsen, Jane; Lund, Bente; Larsen, Erik Hoejkjaer

    2006-01-01

      Udgivelsesdato: DEC  Planning target volumes (PTV) in fractionated radiotherapy still have to be outlined with wide margins to the clinical target volume due to uncertainties arising from daily shift of the prostate position. A recently proposed new method of visualization of the prostate is based on insertion of a thermo-expandable Ni-Ti stent. The current study proposes a new detection algorithm for automated detection of the Ni-Ti stent in electronic portal images. The algorithm is ba...

  8. Towards understanding the influence of electron-gas interactions on imaging in an environmental TEM

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Boothroyd, Chris; Beleggia, Marco

    2011-01-01

    be used. In the differential pumping approach, the gas is confined to the region around the specimen only by pressure-limiting apertures. In order to retain flexibility in the sample region, the pole piece gap and the highest pressure part of the column are relatively large (~7mm). As a result, electron...... on-going work involves the systematic measurements of images, diffraction patterns and energy-loss spectra acquired in the presence of gas, for a variety of different beam current densities, accelerating voltages and choices of specimen....

  9. Ultrafast Coherent Diffraction Imaging with X-ray Free-Electron Lasers

    International Nuclear Information System (INIS)

    Chapman, H N; Bajt, S; Barty, A; Benner, W; Bogan, M; Frank, M; Hau-Riege, S; London, R; Marchesini, S; Spiller, E; Szoke, A; Woods, B; Boutet, S; Hodgson, K; Hajdu, J; Bergh, M; Burmeister, F; Caleman, C; Huldt, G; Maia, F; Seibert, M M; der Spoel, D v

    2006-01-01

    The ultrafast pulses from X-ray free-electron lasers will enable imaging of non-periodic objects at near-atomic resolution [1, Neutze]. These objects could include single molecules, protein complexes, or virus particles. The specimen would be completely destroyed by the pulse in a Coulomb explosion, but that destruction will only happen after the pulse. The scattering from the sample will give structural information about the undamaged object. There are many technical challenges that must be addressed before carrying out such experiments at an XFEL, which we are doing so with experiments at FLASH, the soft-X-ray FEL at DESY

  10. Hierarchy of Electronic Properties of Chemically Derived and Pristine Graphene Probed by Microwave Imaging

    KAUST Repository

    Kundhikanjana, Worasom

    2009-11-11

    Local electrical imaging using microwave impedance microscope is performed on graphene in different modalities, yielding a rich hierarchy of the local conductivity. The low-conductivity graphite oxide and its derivatives show significant electronic inhomogeneity. For the conductive chemical graphene, the residual defects lead to a systematic reduction of the microwave signals. In contrast, the signals on pristine graphene agree well with a lumped-element circuit model. The local impedance information can also be used to verify the electrical contact between overlapped graphene pieces. © 2009 American Chemical Society.

  11. Assessment of dosimetrical performance in 11 Varian a-Si500 electronic portal imaging devices

    International Nuclear Information System (INIS)

    Kavuma, Awusi; Glegg, Martin; Currie, Garry; Elliott, Alex

    2008-01-01

    Dosimetrical characteristics of 11 Varian a-Si-500 electronic portal imaging devices (EPIDs) in clinical use for periods ranging between 10 and 86 months were investigated for consistency of performance and portal dosimetry implications. Properties studied include short-term reproducibility, signal linearity with monitor units, response to reference beam, signal uniformity across the detector panel, signal dependence on field size, dose-rate influence, memory effects and image profiles as a function of monitor units. The EPID measurements were also compared with those of the ionization chambers' to ensure stability of the linear accelerators. Depending on their clinical installation date, the EPIDs were interfaced with one of the two different acquisition control software packages, IAS2/IDU-II or IAS3/IDU-20. Both the EPID age and image acquisition system influenced the dosimetric characteristics with the newer version (IAS3 with IDU-20) giving better data reproducibility and linearity fit than the older version (IAS2 with IDU-II). The relative signal response (uniformity) after 50 MU was better than 95% of the central value and independent of detector. Sensitivity for all EPIDs reduced continuously with increasing dose rates for the newer image acquisition software. In the dose-rate range 100-600 MU min -1 , the maximum variation in sensitivity ranged between 1 and 1.8% for different EPIDs. For memory effects, the increase in the measured signal at the centre of the irradiated field for successive images was within 1.8% and 1.0% for the older and newer acquisition systems, respectively. Image profiles acquired at a lower MU in the radial plane (gun-target) had gradients in measured pixel values of up to 25% for the older system. Detectors with software/hardware versions IAS3/IDU-20 have a high degree of accuracy and are more suitable for routine quantitative IMRT dosimetrical verification.

  12. Level-set segmentation of pulmonary nodules in megavolt electronic portal images using a CT prior

    International Nuclear Information System (INIS)

    Schildkraut, J. S.; Prosser, N.; Savakis, A.; Gomez, J.; Nazareth, D.; Singh, A. K.; Malhotra, H. K.

    2010-01-01

    Purpose: Pulmonary nodules present unique problems during radiation treatment due to nodule position uncertainty that is caused by respiration. The radiation field has to be enlarged to account for nodule motion during treatment. The purpose of this work is to provide a method of locating a pulmonary nodule in a megavolt portal image that can be used to reduce the internal target volume (ITV) during radiation therapy. A reduction in the ITV would result in a decrease in radiation toxicity to healthy tissue. Methods: Eight patients with nonsmall cell lung cancer were used in this study. CT scans that include the pulmonary nodule were captured with a GE Healthcare LightSpeed RT 16 scanner. Megavolt portal images were acquired with a Varian Trilogy unit equipped with an AS1000 electronic portal imaging device. The nodule localization method uses grayscale morphological filtering and level-set segmentation with a prior. The treatment-time portion of the algorithm is implemented on a graphical processing unit. Results: The method was retrospectively tested on eight cases that include a total of 151 megavolt portal image frames. The method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases. The treatment phase portion of the method has a subsecond execution time that makes it suitable for near-real-time nodule localization. Conclusions: A method was developed to localize a pulmonary nodule in a megavolt portal image. The method uses the characteristics of the nodule in a prior CT scan to enhance the nodule in the portal image and to identify the nodule region by level-set segmentation. In a retrospective study, the method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases studied.

  13. Analytical electron microscope based on scanning transmission electron microscope with wavelength dispersive x-ray spectroscopy to realize highly sensitive elemental imaging especially for light elements

    International Nuclear Information System (INIS)

    Koguchi, Masanari; Tsuneta, Ruriko; Anan, Yoshihiro; Nakamae, Koji

    2017-01-01

    An analytical electron microscope based on the scanning transmission electron microscope with wavelength dispersive x-ray spectroscopy (STEM-WDX) to realize highly sensitive elemental imaging especially for light elements has been developed. In this study, a large-solid-angle multi-capillary x-rays lens with a focal length of 5 mm, long-time data acquisition (e.g. longer than 26 h), and a drift-free system made it possible to visualize boron-dopant images in a Si substrate at a detection limit of 0.2 atomic percent. (paper)

  14. Electronic Referrals and Digital Imaging Systems in Ophthalmology: A Global Perspective.

    Science.gov (United States)

    Jeganathan, V Swetha E; Hall, H Nikki; Sanders, Roshini

    2017-01-01

    Ophthalmology departments face intensifying pressure to expedite sight-saving treatments and reduce the global burden of disease. The use of electronic communication systems, digital imaging, and redesigned service care models is imperative for addressing such demands. The recently developed Scottish Eyecare Integration Project involves an electronic referral system from community optometry to the hospital ophthalmology department using National Health Service (NHS) email with digital ophthalmic images attached, via a virtual private network connection. The benefits over the previous system include reduced waiting times, improved triage, e-diagnosis in 20% without the need for hospital attendance, and rapid electronic feedback to referrers. We draw on the experience of the Scottish Eyecare Integration Project and discuss the global applications of this and other advances in teleophthalmology. We focus particularly on the implications for management and screening of chronic disease, such as glaucoma and diabetic eye disease, and ophthalmic disease, such as retinopathy of prematurity where diagnosis is almost entirely and critically dependent on fundus appearance. Currently in Scotland, approximately 75% of all referrals are electronic from community to hospital. The Scottish Eyecare Integration Project is globally the first of its kind and unique in a national health service. Such speedy, safe, and efficient models of communication are geographically sensitive to service provision, especially in remote and rural regions. Along with advances in teleophthalmology, such systems promote the earlier detection of sight-threatening disease and safe follow-up of non-sight-threatening disease in the community. Copyright© 2017 Asia-Pacific Academy of Ophthalmology.

  15. Quantum imaging with incoherently scattered light from a free-electron laser

    Science.gov (United States)

    Schneider, Raimund; Mehringer, Thomas; Mercurio, Giuseppe; Wenthaus, Lukas; Classen, Anton; Brenner, Günter; Gorobtsov, Oleg; Benz, Adrian; Bhatti, Daniel; Bocklage, Lars; Fischer, Birgit; Lazarev, Sergey; Obukhov, Yuri; Schlage, Kai; Skopintsev, Petr; Wagner, Jochen; Waldmann, Felix; Willing, Svenja; Zaluzhnyy, Ivan; Wurth, Wilfried; Vartanyants, Ivan A.; Röhlsberger, Ralf; von Zanthier, Joachim

    2018-02-01

    The advent of accelerator-driven free-electron lasers (FEL) has opened new avenues for high-resolution structure determination via diffraction methods that go far beyond conventional X-ray crystallography methods. These techniques rely on coherent scattering processes that require the maintenance of first-order coherence of the radiation field throughout the imaging procedure. Here we show that higher-order degrees of coherence, displayed in the intensity correlations of incoherently scattered X-rays from an FEL, can be used to image two-dimensional objects with a spatial resolution close to or even below the Abbe limit. This constitutes a new approach towards structure determination based on incoherent processes, including fluorescence emission or wavefront distortions, generally considered detrimental for imaging applications. Our method is an extension of the landmark intensity correlation measurements of Hanbury Brown and Twiss to higher than second order, paving the way towards determination of structure and dynamics of matter in regimes where coherent imaging methods have intrinsic limitations.

  16. Verification of setup errors in external beam radiation therapy using electronic portal imaging

    International Nuclear Information System (INIS)

    Krishna Murthy, K.; Al-Rahbi, Zakiya; Sivakumar, S.S.; Davis, C.A.; Ravichandran, R.

    2008-01-01

    The objective of this study was to conduct an audit on QA aspects of treatment delivery by the verification of the treatment fields position on different days to document the efficiency of immobilization methods and reproducibility of treatment. A retrospective study was carried out on 60 patients, each 20 treated for head and neck, breast, and pelvic sites; and a total of 506 images obtained by electronic portal imaging device (EPID) were analyzed. The portal images acquired using the EPID systems attached to the Varian linear accelerators were superimposed on the reference images. The anatomy matching software (Varian portal Vision. 6.0) was used, and the displacements in two dimensions and rotation were noted for each treated field to study the patient setup errors. The percentages of mean deviations more than 3 mm in lateral (X) and longitudinal (Y) directions were 17.5%, 11.25%, and 7.5% for breast, pelvis, and head and neck cases respectively. In all cases, the percentage of mean deviation with more than 5 mm error was 0.83%. The maximum average mean deviation in all the cases was 1.87. The average mean SD along X and Y directions in all the cases was less than 2.65. The results revealed that the ranges of setup errors are site specific and immobilization methods improve reproducibility. The observed variations were well within the limits. The study confirmed the accuracy and quality of treatments delivered to the patients. (author)

  17. Terahertz imaging and spectroscopy based on hot electron bolometer (HEB) heterodyne detection

    Science.gov (United States)

    Gerecht, Eyal; You, Lixing

    2008-02-01

    Imaging and spectroscopy at terahertz frequencies have great potential for healthcare, plasma diagnostics, and homeland security applications. Terahertz frequencies correspond to energy level transitions of important molecules in biology and astrophysics. Terahertz radiation (T-rays) can penetrate clothing and, to some extent, can also penetrate biological materials. Because of their shorter wavelengths, they offer higher spatial resolution than do microwaves or millimeter waves. We are developing hot electron bolometer (HEB) mixer receivers for heterodyne detection at terahertz frequencies. HEB detectors provide unprecedented sensitivity and spectral resolution at terahertz frequencies. We describe the development of a two-pixel focal plane array (FPA) based on HEB technology. Furthermore, we have demonstrated a fully automated, two-dimensional scanning, passive imaging system based on our HEB technology operating at 0.85 THz. Our high spectral resolution terahertz imager has a total system noise equivalent temperature difference (NEΔT) value of better than 0.5 K and a spatial resolution of a few millimeters. HEB technology is becoming the basis for advanced terahertz imaging and spectroscopic technologies for the study of biological and chemical agents over the entire terahertz spectrum.

  18. Electron paramagnetic resonance image reconstruction with total variation and curvelets regularization

    Science.gov (United States)

    Durand, Sylvain; Frapart, Yves-Michel; Kerebel, Maud

    2017-11-01

    Spatial electron paramagnetic resonance imaging (EPRI) is a recent method to localize and characterize free radicals in vivo or in vitro, leading to applications in material and biomedical sciences. To improve the quality of the reconstruction obtained by EPRI, a variational method is proposed to inverse the image formation model. It is based on a least-square data-fidelity term and the total variation and Besov seminorm for the regularization term. To fully comprehend the Besov seminorm, an implementation using the curvelet transform and the L 1 norm enforcing the sparsity is proposed. It allows our model to reconstruct both image where acquisition information are missing and image with details in textured areas, thus opening possibilities to reduce acquisition times. To implement the minimization problem using the algorithm developed by Chambolle and Pock, a thorough analysis of the direct model is undertaken and the latter is inverted while avoiding the use of filtered backprojection (FBP) and of non-uniform Fourier transform. Numerical experiments are carried out on simulated data, where the proposed model outperforms both visually and quantitatively the classical model using deconvolution and FBP. Improved reconstructions on real data, acquired on an irradiated distal phalanx, were successfully obtained.

  19. Digital imaging and electronic patient records in pathology using an integrated department information system with PACS.

    Science.gov (United States)

    Kalinski, Thomas; Hofmann, Harald; Franke, Dagmar-Sybilla; Roessner, Albert

    2002-01-01

    Picture archiving and communication systems have been widely used in radiology thus far. Owing to the progress made in digital photo technology, their use in medicine opens up further opportunities. In the field of pathology, digital imaging offers new possiblities for the documentation of macroscopic and microscopic findings. Digital imaging has the advantage that the data is permanently and readily available, independent of conventional archives. In the past, PACS was a separate entity. Meanwhile, however, PACS has been integrated in DIS, the department information system, which was also run separately in former times. The combination of these two systems makes the administration of patient data, findings and images easier. Moreover, thanks to the introduction of special communication standards, a data exchange between different department information systems and hospital information systems (HIS) is possible. This provides the basis for a communication platform in medicine, constituting an electronic patient record (EPR) that permits an interdisciplinary treatment of patients by providing data of findings and images from clinics treating the same patient. As the pathologic diagnosis represents a central and often therapy-determining component, it is of utmost importance to add pathologic diagnoses to the EPR. Furthermore, the pathologist's work is considerably facilitated when he is able to retrieve additional data from the patient file. In this article, we describe our experience gained with the combined PACS and DIS systems recently installed at the Department of Pathology, University of Magdeburg. Moreover, we evaluate the current situation and future prospects for PACS in pathology.

  20. Comparative electron microscopy and image analysis of oxy- and deoxy-hemocyanin from the spiny lobster Panulirus interruptus

    NARCIS (Netherlands)

    Haas, Felix de; Breemen, Jan F.L. van; Boekema, Egbert J.; Keegstra, Wilko; Bruggen, Ernst F.J. van

    1993-01-01

    Structural differences between oxy-hemocyanin and deoxy-hemocyanin from the spiny lobster P. interruptus were studied by electron microscopy and image analysis of negatively stained preparations. Projections of the hexameric P. interruptus hemocyanin from electron microscopy were compared with

  1. A comparison between the electronic magnification (EM) and true magnification (TM) of breast phantom images using a CDMAM phantom

    International Nuclear Information System (INIS)

    Vahey, Karou; Ryan, Elaine; McLean, Don; Poulos, Ann; Rickard, Mary

    2012-01-01

    Purpose: To provide a comparison between the image quality of electronically magnified (EM) and geometric, or true, magnification (TM) mammographic images. Materials and methods: One Computed Radiography (CR), one Digital Radiography (DR) and two screen–film (S–F) imaging systems were investigated. A Contrast-Detail Mammography (CDMAM) phantom was used as a test object. Three contact images and three sets of TM images with a magnification factor of 1.8 were taken on all systems. Software was used to zoom the contact images by a factor of 1.8 to produce EM images. Two observers evaluated all of the images. An Image Quality Figure and contrast detail curve were used to analyze the observer data and Mann–Whitney U-tests were performed to determine the statistical significance of the results. Results: No significant differences were found between soft copy and hard copy for any imaging modality. No significant difference in contrast detail detectability (CDD) was seen between EM images from the two digital systems and TM images on S–F systems. The results for the DR EM images and S–F TM images also showed no differences. The CDD of DR TM images was significantly better than both EM and S–F TM images. Conclusion: Digitally zoomed images offer the same level of CDD as S–F TM images, and so may be viably used in their place. DR systems offer greater CDD than conventional S–F images, when comparing the TM images. This implies that doses can be greatly reduced for TM views using DR systems, while maintaining acceptable image quality.

  2. Synthesis of (E-2,4-Dinitro-N-((2E,4E-4-phenyl-5-(pyrrolidin-1-ylpenta-2,4-dienylideneaniline

    Directory of Open Access Journals (Sweden)

    Mostafa Fesanghari

    2009-07-01

    Full Text Available (E-2,4-Dinitro-N-((2E,4E-4-phenyl-5-(pyrrolidin-1-ylpenta-2,4-dienylidene aniline dye was prepared in one pot by reaction of premade N-2,4-dinitrophenyl-3-phenylpyridinium chloride (DNPPC and pyrrolidine in absolute MeOH.

  3. Reconstruction of an Non-Monochromatically Illuminated Object Imaged through an Electron Microscope with a Fluctuating Electromagnetic Field

    NARCIS (Netherlands)

    Hoenders, B.J.

    1975-01-01

    It is shown that a weak phase object imaged by an electron microscope within the presence of instabilities of the lense currents and the acceleration voltage, fluctuating electromagnetic field, can be reconstructed from the intensity distribution in the image plane. Perfectly incoherent illumination

  4. Annular dark field electron microscope images with better than 2 A resolution at 100 kV

    International Nuclear Information System (INIS)

    Shin, D.H.; Kirkland, E.J.; Silcox, J.

    1989-01-01

    High-resolution scanning transmission electron microscope (STEM) images in the annular dark field (ADF) imaging mode approaching the theoretical point-to-point resolution limit are presented. The ADF images were obtained from a high T c superconducting YBa 2 Cu 3 O 7-x thin-film specimen at 100 kV. The 1.9 A resolution lattice image, which is the smallest lattice spacing in the specimen, corresponds to the minimum resolvable spatial frequency with 5% contrast in the contrast transfer function for annular dark field, and is smaller than the resolution limit given by the Rayleigh criterion. This demonstrates that STEM ADF imaging can have a resolution approximately 40% better than that of the bright field conventional transmission electron microscope (CTEM) imaging at Scherzer condition

  5. SU-E-T-775: Use of Electronic Portal Imaging Device (EPID) for Quality Assurance (QA) of Electron Beams On Varian Truebeam System

    Energy Technology Data Exchange (ETDEWEB)

    Cai, B; Yaddanapudi, S; Sun, B; Li, H; Noel, C; Mutic, S; Goddu, S [Department of Radiation Oncology, Washington University in St Louis, St. Louis, MO (United States)

    2015-06-15

    Purpose: In a previous study we have demonstrated the feasibility of using EPID to QA electron beam parameters on a single Varian TrueBeam LINAC. This study aims to provide further investigation on (1) reproducibility of using EPID to detect electron beam energy changes on multiple machines and (2) evaluation of appropriate calibration methods to compare results from different EPIDs. Methods: Ad-hoc mode electron beam images were acquired in developer mode with XML code. Electron beam data were collected on a total of six machines from four institutions. A custom-designed double-wedge phantom was placed on the EPID detector. Two calibration methods - Pixel Sensitivity Map (PSM) and Large Source-to-Imager Distance Flood Field (LSID-FF) - were used. To test the sensitivity of EPID in detecting energy drifts, Bending Magnet Current (BMC) was detuned to invoke energy changes corresponding to ∼±1.5 mm change in R50% of PDD on two machines from two institutions. Percent depth ionization (PDI) curves were then analyzed and compared with the respective baseline images using LSID-FF calibration. For reproducibility testing, open field EPID images and images with a standard testing phantom were collected on multiple machines. Images with and without PSM correction for same energies on different machines were overlaid and compared. Results: Two pixel shifts were observed in PDI curve when energy changes exceeded the TG142 tolerance. PSM showed the potential to correct the differences in pixel response of different imagers. With PSM correction, the histogram of images differences obtained from different machines showed narrower distributions than those images without PSM correction. Conclusion: EPID is sensitive for electron energy changes and the results are reproducible on different machines. When overlaying images from different machines, PSM showed the ability to partially eliminate the intrinsic variation of various imagers. Research Funding from Varian Medical Systems

  6. Electronic structure of the cuprate superconducting and pseudogap phases from spectroscopic imaging STM

    Science.gov (United States)

    Schmidt, A. R.; Fujita, K.; Kim, E.-A.; Lawler, M. J.; Eisaki, H.; Uchida, S.; Lee, D.-H.; Davis, J. C.

    2011-06-01

    We survey the use of spectroscopic imaging scanning tunneling microscopy (SI-STM) to probe the electronic structure of underdoped cuprates. Two distinct classes of electronic states are observed in both the d-wave superconducting (dSC) and the pseudogap (PG) phases. The first class consists of the dispersive Bogoliubov quasiparticle excitations of a homogeneous d-wave superconductor, existing below a lower energy scale E=Δ0. We find that the Bogoliubov quasiparticle interference (QPI) signatures of delocalized Cooper pairing are restricted to a k-space arc, which terminates near the lines connecting k=±(π/a0,0) to k=±(0,π/a0). This arc shrinks continuously with decreasing hole density such that Luttinger's theorem could be satisfied if it represents the front side of a hole-pocket that is bounded behind by the lines between k=±(π/a0,0) and k=±(0,π/a0). In both phases, the only broken symmetries detected for the |E|modulations, locally breaking both rotational and translational symmetries, coexist with this intra-unit-cell electronic symmetry breaking at E=Δ1. Their characteristic wavevector Q is determined by the k-space points where Bogoliubov QPI terminates and therefore changes continuously with doping. The distinct broken electronic symmetry states (intra-unit-cell and finite Q) coexisting at E~Δ1 are found to be indistinguishable in the dSC and PG phases. The next challenge for SI-STM studies is to determine the relationship of the E~Δ1 broken symmetry electronic states with the PG phase, and with the E<Δ0 states associated with Cooper pairing.

  7. Picosecond phase-velocity dispersion of hypersonic phonons imaged with ultrafast electron microscopy

    International Nuclear Information System (INIS)

    Cremons, Daniel R.; Du, Daniel X.; Flannigan, David J.

    2017-01-01

    We describe the direct imaging—with four-dimensional ultrafast electron microscopy—of the emergence, evolution, dispersion, and decay of photoexcited, hypersonic coherent acoustic phonons in nanoscale germanium wedges. Coherent strain waves generated via ultrafast in situ photoexcitation were imaged propagating with initial phase velocities of up to 35 km/s across discrete micrometer-scale crystal regions. We then observe that, while each wave front travels at a constant velocity, the entire wave train evolves with a time-varying phase-velocity dispersion, displaying a single-exponential decay to the longitudinal speed of sound (5 km/s) and with a mean lifetime of 280 ps. We also find that the wave trains propagate along a single in-plane direction oriented parallel to striations introduced during specimen preparation, independent of crystallographic direction. Elastic-plate modeling indicates the dynamics arise from excitation of a single, symmetric (dilatational) guided acoustic mode. Further, by precisely determining the experiment time-zero position with a plasma-lensing method, we find that wave-front emergence occurs approximately 100 ps after femtosecond photoexcitation, which matches well with Auger recombination times in germanium. We conclude by discussing the similarities between the imaged hypersonic strain-wave dynamics and electron/hole plasma-wave dynamics in strongly photoexcited semiconductors.

  8. Immunocytochemistry by electron spectroscopic imaging using well defined boronated monovalent antibody fragments.

    Science.gov (United States)

    Kessels, M M; Qualmann, B; Sierralta, W D

    1996-01-01

    Contributing to the rapidly developing field of immunoelectron microscopy a new kind of markers has been created. The element boron, incorporated as very stable carborane clusters into different kinds of peptides, served as a marker detectable by electron spectroscopic imaging (ESI)--an electron microscopic technique with high-resolution potential. Covalently linked immunoreagents conspicuous by the small size of both antigen recognizing part and marker moiety are accessible by using peptide concepts for label construction and their conjugation with Fab' fragments. Due to a specific labeling of the free thiol groups of the Fab' fragments, the antigen binding capacity was not affected by the attachment of the markers and the resulting immunoprobes exhibited an elongated shape with the antigen combining site and the label located at opposite ends. The labeling densities observed with these reagents were found to be significantly higher than those obtained by using conventional colloidal gold methods. Combined with digital image processing and analysis systems, boron-based ESI proved to be a powerful approach in ultrastructural immunocytochemistry employing pre- and post-embedding methods.

  9. Design of the 2D electron cyclotron emission imaging instrument for the J-TEXT tokamak.

    Science.gov (United States)

    Pan, X M; Yang, Z J; Ma, X D; Zhu, Y L; Luhmann, N C; Domier, C W; Ruan, B W; Zhuang, G

    2016-11-01

    A new 2D Electron Cyclotron Emission Imaging (ECEI) diagnostic is being developed for the J-TEXT tokamak. It will provide the 2D electron temperature information with high spatial, temporal, and temperature resolution. The new ECEI instrument is being designed to support fundamental physics investigations on J-TEXT including MHD, disruption prediction, and energy transport. The diagnostic contains two dual dipole antenna arrays corresponding to F band (90-140 GHz) and W band (75-110 GHz), respectively, and comprises a total of 256 channels. The system can observe the same magnetic surface at both the high field side and low field side simultaneously. An advanced optical system has been designed which permits the two arrays to focus on a wide continuous region or two radially separate regions with high imaging spatial resolution. It also incorporates excellent field curvature correction with field curvature adjustment lenses. An overview of the diagnostic and the technical progress including the new remote control technique are presented.

  10. Electronic structure and STM imaging of the KBr-InSb interface

    Energy Technology Data Exchange (ETDEWEB)

    Ciochoń, Piotr, E-mail: ciochon.piotr@gmail.com; Olszowska, Natalia; Kołodziej, Jacek J.

    2017-07-01

    Highlights: • The structure of the InSb (001) surface covered with thin KBr layers is reported. • KBr growth does not perturb strongly the structure of a clean InSb surface. • A model of the system with KBr treated as a thin dielectric layer is proposed. • The atomic structure of the KBr-InSb interface is directly imaged using STM. - Abstract: We study the properties of the InSb (001) surface covered with ultrathin KBr films, with a thickness of 1–4 ML. KBr deposition does not strongly perturb the crystallographic structure of the InSb surface and the electronic structure of the substrate also remains unaffected by the overlayer. A simple model of the studied system is proposed, in which a thin KBr layer is treated as a dielectric film, modifying potential barrier for the electrons tunneling to/from the InSb substrate. Apparent step heights on the KBr film, measured using scanning tunneling microscope (STM), agree well with the predictions of the model and the atomically-resolved STM images show the structure of the InSb-KBr interface. Our results demonstrate that STM may be used as a tool for investigations of the semiconductor–insulator interfaces.

  11. Picosecond phase-velocity dispersion of hypersonic phonons imaged with ultrafast electron microscopy

    Science.gov (United States)

    Cremons, Daniel R.; Du, Daniel X.; Flannigan, David J.

    2017-12-01

    Here, we describe the direct imaging—with four-dimensional ultrafast electron microscopy—of the emergence, evolution, dispersion, and decay of photoexcited, hypersonic coherent acoustic phonons in nanoscale germanium wedges. Coherent strain waves generated via ultrafast in situ photoexcitation were imaged propagating with initial phase velocities of up to 35 km/s across discrete micrometer-scale crystal regions. We observe that, while each wave front travels at a constant velocity, the entire wave train evolves with a time-varying phase-velocity dispersion, displaying a single-exponential decay to the longitudinal speed of sound (5 km/s) and with a mean lifetime of 280 ps. We also find that the wave trains propagate along a single in-plane direction oriented parallel to striations introduced during specimen preparation, independent of crystallographic direction. Elastic-plate modeling indicates the dynamics arise from excitation of a single, symmetric (dilatational) guided acoustic mode. Further, by precisely determining the experiment time-zero position with a plasma-lensing method, we find that wave-front emergence occurs approximately 100 ps after femtosecond photoexcitation, which matches well with Auger recombination times in germanium. We conclude by discussing the similarities between the imaged hypersonic strain-wave dynamics and electron/hole plasma-wave dynamics in strongly photoexcited semiconductors.

  12. Design of the 2D electron cyclotron emission imaging instrument for the J-TEXT tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Pan, X. M.; Yang, Z. J., E-mail: yangzj@hust.edu.cn; Ma, X. D.; Ruan, B. W.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Zhu, Y. L. [School of Physics, University of Science and Technology of China, Anhui 230026 (China); Luhmann, N. C.; Domier, C. W. [Davis Millimeter Wave Research Center, University of California, Davis, California 95616 (United States)

    2016-11-15

    A new 2D Electron Cyclotron Emission Imaging (ECEI) diagnostic is being developed for the J-TEXT tokamak. It will provide the 2D electron temperature information with high spatial, temporal, and temperature resolution. The new ECEI instrument is being designed to support fundamental physics investigations on J-TEXT including MHD, disruption prediction, and energy transport. The diagnostic contains two dual dipole antenna arrays corresponding to F band (90-140 GHz) and W band (75-110 GHz), respectively, and comprises a total of 256 channels. The system can observe the same magnetic surface at both the high field side and low field side simultaneously. An advanced optical system has been designed which permits the two arrays to focus on a wide continuous region or two radially separate regions with high imaging spatial resolution. It also incorporates excellent field curvature correction with field curvature adjustment lenses. An overview of the diagnostic and the technical progress including the new remote control technique are presented.

  13. Characterization of intact subcellular bodies in whole bacteria by cryo-electron tomography and spectroscopic imaging.

    Science.gov (United States)

    Comolli, L R; Kundmann, M; Downing, K H

    2006-07-01

    We illustrate the combined use of cryo-electron tomography and spectroscopic difference imaging in the study of subcellular structure and subcellular bodies in whole bacteria. We limited our goal and focus to bodies with a distinct elemental composition that was in a sufficiently high concentration to provide the necessary signal-to-noise level at the relatively large sample thicknesses of the intact cell. This combination proved very powerful, as demonstrated by the identification of a phosphorus-rich body in Caulobacter crescentus. We also confirmed the presence of a body rich in carbon, demonstrated that these two types of bodies are readily recognized and distinguished from each other, and provided, for the first time to our knowledge, structural information about them in their intact state. In addition, we also showed the presence of a similar type of phosphorus-rich body in Deinococcus grandis, a member of a completely unrelated bacteria genus. Cryo-electron microscopy and tomography allowed the study of the biogenesis and morphology of these bodies at resolutions better than 10 nm, whereas spectroscopic difference imaging provided a direct identification of their chemical composition.

  14. Charge transport through image charged stabilized states in a single molecule single electron transistor device

    International Nuclear Information System (INIS)

    Hedegard, Per; Bjornholm, Thomas

    2005-01-01

    The present paper gives an elaborate theoretical description of a new molecular charge transport mechanism applying to a single molecule trapped between two macroscopic electrodes in a solid state device. It is shown by a Hubbard type model of the electronic and electrostatic interactions, that the close proximity of metal electrodes may allow electrons to tunnel from the electrode directly into very localized image charge stabilized states on the molecule. Due to this mechanism, an exceptionally large number of redox states may be visited within an energy scale which would normally not allow the molecular HOMO-LUMO gap to be transversed. With a reasonable set of parameters, a good fit to recent experimental values may be obtained. The theoretical model is furthermore used to search for the physical boundaries of this effect, and it is found that a rather narrow geometrical space is available for the new mechanism to work: in the specific case of oligophenylenevinylene molecules recently explored in such devices several atoms in the terminal benzene rings need to be at van der Waal's distance to the electrode in order for the mechanism to work. The model predicts, that chemisorption of the terminal benzene rings too gold electrodes will impede the image charge effect very significantly because the molecule is pushed away from the electrode by the covalent thiol-gold bond

  15. Initial Clinical Experience Performing Patient Treatment Verification With an Electronic Portal Imaging Device Transit Dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Berry, Sean L., E-mail: BerryS@MSKCC.org [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Polvorosa, Cynthia; Cheng, Simon; Deutsch, Israel; Chao, K. S. Clifford; Wuu, Cheng-Shie [Department of Radiation Oncology, Columbia University, New York, New York (United States)

    2014-01-01

    Purpose: To prospectively evaluate a 2-dimensional transit dosimetry algorithm's performance on a patient population and to analyze the issues that would arise in a widespread clinical adoption of transit electronic portal imaging device (EPID) dosimetry. Methods and Materials: Eleven patients were enrolled on the protocol; 9 completed and were analyzed. Pretreatment intensity modulated radiation therapy (IMRT) patient-specific quality assurance was performed using a stringent local 3%, 3-mm γ criterion to verify that the planned fluence had been appropriately transferred to and delivered by the linear accelerator. Transit dosimetric EPID images were then acquired during treatment and compared offline with predicted transit images using a global 5%, 3-mm γ criterion. Results: There were 288 transit images analyzed. The overall γ pass rate was 89.1% ± 9.8% (average ± 1 SD). For the subset of images for which the linear accelerator couch did not interfere with the measurement, the γ pass rate was 95.7% ± 2.4%. A case study is presented in which the transit dosimetry algorithm was able to identify that a lung patient's bilateral pleural effusion had resolved in the time between the planning CT scan and the treatment. Conclusions: The EPID transit dosimetry algorithm under consideration, previously described and verified in a phantom study, is feasible for use in treatment delivery verification for real patients. Two-dimensional EPID transit dosimetry can play an important role in indicating when a treatment delivery is inconsistent with the original plan.

  16. Sub-nanometre resolution imaging of polymer-fullerene photovoltaic blends using energy-filtered scanning electron microscopy.

    Science.gov (United States)

    Masters, Robert C; Pearson, Andrew J; Glen, Tom S; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M; Lidzey, David G; Rodenburg, Cornelia

    2015-04-24

    The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials.

  17. Sub-nanometre resolution imaging of polymer–fullerene photovoltaic blends using energy-filtered scanning electron microscopy

    Science.gov (United States)

    Masters, Robert C.; Pearson, Andrew J.; Glen, Tom S.; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M.; Lidzey, David G.; Rodenburg, Cornelia

    2015-01-01

    The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials. PMID:25906738

  18. Imaging modes for potential mapping in semiconductor devices by electron holography with improved lateral resolution

    Energy Technology Data Exchange (ETDEWEB)

    Sickmann, Jan, E-mail: jan.sickmann@triebenberg.de [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01069 Dresden (Germany); Formanek, Petr; Linck, Martin [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01069 Dresden (Germany); Muehle, Uwe [Institut fuer Werkstoffwissenschaft, Technische Universitaet Bergakademie Freiberg, 09599 Freiberg (Germany); Lichte, Hannes [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01069 Dresden (Germany)

    2011-03-15

    Electron holography is the highest resolving tool for dopant profiling at nanometre-scale resolution. In order to measure the object areas of interest in a hologram, both a wide field of view and a sufficient lateral resolution are required. The usual path of rays for recording holograms with an electron biprism using the standard objective lens does not meet these requirements, because the field of view amounts to some 10 nm only, however, at a resolution of 0.1 nm better than needed here. Therefore, instead of the standard objective lens, the Lorentz lens is widely used for holography of semiconductors, since it provides a field of view up to 1000 nm at a sufficient lateral resolution of about 10 nm. Since the size of semiconductor structures is steadily shrinking, there is now a need for better lateral resolution at an appropriate field of view. Therefore, additional paths of rays for recording holograms are studied with special emphasis on the parameters field of view and lateral resolution. The findings allow an optimized scheme with a field of view of 200 nm and a lateral resolution of 3.3 nm filling the gap between the existing set-ups. In addition, the Lorentz lens is no longer required for investigation of non-magnetic materials, since the new paths of rays are realized with the standard objective lens and diffraction lens. An example proves the applicability of this arrangement for future semiconductor technology. -- Research highlights: {yields} Imaging modes for potential mapping in semiconductor devices by electron holography. {yields} Using objective and diffraction lens for imaging instead of Lorentz lens. {yields} Detailed investigation of four different paths of rays and its basic parameters for holographic application: field of view, lateral resolution, signal resolution. {yields} Measuring the phase profile of a field effect transistor with 3 nm lateral resolution at field of view of 200 nm.

  19. Development of a SEM-based low-energy in-line electron holography microscope for individual particle imaging.

    Science.gov (United States)

    Adaniya, Hidehito; Cheung, Martin; Cassidy, Cathal; Yamashita, Masao; Shintake, Tsumoru

    2018-05-01

    A new SEM-based in-line electron holography microscope has been under development. The microscope utilizes conventional SEM and BF-STEM functionality to allow for rapid searching of the specimen of interest, seamless interchange between SEM, BF-STEM and holographic imaging modes, and makes use of coherent low-energy in-line electron holography to obtain low-dose, high-contrast images of light element materials. We report here an overview of the instrumentation and first experimental results on gold nano-particles and carbon nano-fibers for system performance tests. Reconstructed images obtained from the holographic imaging mode of the new microscope show substantial image contrast and resolution compared to those acquired by SEM and BF-STEM modes, demonstrating the feasibility of high-contrast imaging via low-energy in-line electron holography. The prospect of utilizing the new microscope to image purified biological specimens at the individual particle level is discussed and electron optical issues and challenges to further improve resolution and contrast are considered. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Foucault imaging and small-angle electron diffraction in controlled external magnetic fields.

    Science.gov (United States)

    Nakajima, Hiroshi; Kotani, Atsuhiro; Harada, Ken; Ishii, Yui; Mori, Shigeo

    2016-12-01

    We report a method for acquiring Foucault images and small-angle electron diffraction patterns in external magnetic fields using a conventional transmission electron microscope without any modification. In the electron optical system that we have constructed, external magnetic fields parallel to the optical axis can be controlled using the objective lens pole piece under weak excitation conditions in the Foucault mode and the diffraction mode. We observe two ferromagnetic perovskite-type manganese oxides, La 0.7 Sr 0.3 MnO 3 (LSMO) and Nd 0.5 Sr 0.5 MnO 3 , in order to visualize magnetic domains and their magnetic responses to external magnetic fields. In rhombohedral-structured LSMO, pinning of magnetic domain walls at crystallographic twin boundaries was found to have a strong influence on the generation of new magnetic domains in external applied magnetic fields. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Front-end electronics and data acquisition system for imaging atmospheric Cherenkov telescopes

    International Nuclear Information System (INIS)

    Chen, Y.T.; La Taille, C. de; Suomijärvi, T.; Cao, Z.; Deligny, O.; Dulucq, F.; Ge, M.M.; Lhenry-Yvon, I.; Martin-Chassard, G.; Nguyen Trung, T.; Wanlin, E.; Xiao, G.; Yin, L.Q.; Yun Ky, B.; Zhang, L.; Zhang, H.Y.; Zhang, S.S.; Zhu, Z.

    2015-01-01

    In this paper, a front-end electronics based on an application-specific integrated circuit (ASIC) is presented for the future imaging atmospheric Cherenkov telescopes (IACTs). To achieve this purpose, a 16-channel ASIC chip, PARISROC 2 (Photomultiplier ARray Integrated in SiGe ReadOut Chip) is used in the analog signal processing and digitization. The digitized results are sent to the server by a user-defined User Datagram Protocol/Internet Protocol (UDP/IP) hardcore engine through Ethernet that is managed by a FPGA. A prototype electronics fulfilling the requirements of the Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO) project has been designed, fabricated and tested to prove the concept of the design. A detailed description of the development with the results of the test measurements are presented. By using a new input structure and a new configuration of the ASIC, the dynamic range of the circuit is extended. A highly precise-time calibrating algorithm is also proposed, verified and optimized for the mass production. The test results suggest that the proposed electronics design fulfills the general specification of the future IACTs

  2. Serial single molecule electron diffraction imaging: diffraction background of superfluid helium droplets

    Science.gov (United States)

    Zhang, Jie; He, Yunteng; Lei, Lei; Alghamdi, Maha; Oswalt, Andrew; Kong, Wei

    2017-08-01

    In an effort to solve the crystallization problem in crystallography, we have been engaged in developing a method termed "serial single molecule electron diffraction imaging" (SS-EDI). The unique features of SS-EDI are superfluid helium droplet cooling and field-induced orientation: together the two features constitute a molecular goniometer. Unfortunately, the helium atoms surrounding the sample molecule also contribute to a diffraction background. In this report, we analyze the properties of a superfluid helium droplet beam and its doping statistics, and demonstrate the feasibility of overcoming the background issue by using the velocity slip phenomenon of a pulsed droplet beam. Electron diffraction profiles and pair correlation functions of ferrocene-monomer-doped droplets and iodine-nanocluster-doped droplets are presented. The timing of the pulsed electron gun and the effective doping efficiency under different dopant pressures can both be controlled for size selection. This work clears any doubt of the effectiveness of superfluid helium droplets in SS-EDI, thereby advancing the effort in demonstrating the "proof-of-concept" one step further.

  3. Front-end electronics and data acquisition system for imaging atmospheric Cherenkov telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.T., E-mail: chenytao@ynu.edu.cn [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Yunnan University, 650091 Kunming (China); La Taille, C. de [OMEGA (UMS 3605) - IN2P3/CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Suomijärvi, T. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Cao, Z. [Institute of High Energy Physics, 100049 Beijing (China); Deligny, O. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Dulucq, F. [OMEGA (UMS 3605) - IN2P3/CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Ge, M.M. [Yunnan University, 650091 Kunming (China); Lhenry-Yvon, I. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Martin-Chassard, G. [OMEGA (UMS 3605) - IN2P3/CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Nguyen Trung, T.; Wanlin, E. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Xiao, G.; Yin, L.Q. [Institute of High Energy Physics, 100049 Beijing (China); Yun Ky, B. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Zhang, L. [Yunnan University, 650091 Kunming (China); Zhang, H.Y. [Tsinghua University, 100084 Beijing (China); Zhang, S.S.; Zhu, Z. [Institute of High Energy Physics, 100049 Beijing (China)

    2015-09-21

    In this paper, a front-end electronics based on an application-specific integrated circuit (ASIC) is presented for the future imaging atmospheric Cherenkov telescopes (IACTs). To achieve this purpose, a 16-channel ASIC chip, PARISROC 2 (Photomultiplier ARray Integrated in SiGe ReadOut Chip) is used in the analog signal processing and digitization. The digitized results are sent to the server by a user-defined User Datagram Protocol/Internet Protocol (UDP/IP) hardcore engine through Ethernet that is managed by a FPGA. A prototype electronics fulfilling the requirements of the Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO) project has been designed, fabricated and tested to prove the concept of the design. A detailed description of the development with the results of the test measurements are presented. By using a new input structure and a new configuration of the ASIC, the dynamic range of the circuit is extended. A highly precise-time calibrating algorithm is also proposed, verified and optimized for the mass production. The test results suggest that the proposed electronics design fulfills the general specification of the future IACTs.

  4. Application of backscatter electrons for large area imaging of cavities produced by neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Pastukhov, V.I. [Joint Stock Company “Institute of Nuclear Materials” (JSC “INM”), Zarechny, Sverdlovsk Region (Russian Federation); Ural Federal University Named After the First President of Russia, B. N. Yeltsyn, Ekaterinburg (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Averin, S.A.; Panchenko, V.L. [Joint Stock Company “Institute of Nuclear Materials” (JSC “INM”), Zarechny, Sverdlovsk Region (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Portnykh, I.A. [Joint Stock Company “Institute of Nuclear Materials” (JSC “INM”), Zarechny, Sverdlovsk Region (Russian Federation); Freyer, P.D. [Westinghouse Electric Company, Pittsburgh, PA (United States); Giannuzzi, L.A. [L.A. Giannuzzi & Associates LLC, Fort Myers, FL (United States); Garner, F.A., E-mail: frank.garner@dslextreme.com [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Radiation Effects Consulting LLC, Richland, WA (United States); Texas A& M University, College Station, TX (United States)

    2016-11-15

    It is shown that with proper optimization, backscattered electrons in a scanning electron microscope can produce images of cavity distribution in austenitic steels over a large specimen surface for a depth of ∼500–700 nm, eliminating the need for electropolishing or multiple specimen production. This technique is especially useful for quantifying cavity structures when the specimen is known or suspected to contain very heterogeneous distributions of cavities. Examples are shown for cold-worked EK-164, a very heterogeneously-swelling Russian fast reactor fuel cladding steel and also for AISI 304, a homogeneously-swelling Western steel used for major structural components of light water cooled reactors. This non-destructive overview method of quantifying cavity distribution can be used to direct the location and number of required focused ion beam prepared transmission electron microscopy specimens for examination of either neutron or ion-irradiated specimens. This technique can also be applied in stereo mode to quantify the depth dependence of cavity distributions.

  5. Evaluation of set-of errors in pelvic irradiation with electronic portal imaging device

    International Nuclear Information System (INIS)

    Wu Xiaoying; Zhang Zhen; Wang Wenchao; Ren Jun; Guo Xiaomei; Lu Huizhong

    2007-01-01

    Objective: Evaluate the systematic and random set-up error in the pelvic irradiation u- sing electronic portal imaging device(EPID) to provide institution-specific margin for PTV design in pelvic cancer treatment planning with 3D conformal therapy and/or IMRT. Methods: From May to August 2005, twelve patients who received pelvic irradiation, were involved in this study. CT simulations were performed and DRRs were generated as the reference images. Ant-post and lateral portal images were taken daily, and total of 244 sets of EPID images were collected for the whole group. The translational shifts along right-left, superior-inferior and anterior-posterior directions were calculated with aligning the pelvic bony structures on the DRRs and electronic portal images. The systematic and random setup errors were evaluated based on the 244 sets of data. PTV margin was assessed assuming target rotation was negligible. Results: In the right- left (R-L), superior-inferior (S-I) and anterior-posterior (A-P) directions, the maximum shifts were 9.9, 14.0 and 21.1 mm and the systematic setup errors were 0.5, 0.2 and 2.3 mm respectively. For all 244 sets of data in this study, the frequency of the shift larger than 10 mm were 0% (R-L), 1% (S-I) and 3% (A -P); and in R-L and S-I direction, 92% and 91% of the times the shift was smaller than 5 mm. However, only 79% of the times the A-P shift was less than 5 mm. Conclusions: It is suggested in this study that in order to achieve a target coverage of better than 95% of the times throughout the pelvic irradiation in our institution, a 5 mm PTV margin in right-left and superior-inferior directions is required, however, the anterior-posterior margin needs to be increased to at least 10 mm. One needs to be cautious though when applying the PTV margin derived from small sample of patient population to individual patient. (authors)

  6. Determination of line edge roughness in low dose top-down scanning electron microscopy images

    Science.gov (United States)

    Verduin, T.; Kruit, P.; Hagen, C. W.

    2014-04-01

    We investigated off-line metrology for LER determination in low-dose SEM images to reduce the acquisition time and the risk of shrinkage. Our first attempts are based on filtering noisy (experimental) SEM images and use peak detection to measure the edge displacements and calculating the discrete PSD. However, the result of the filtering is that the power spectrum of the filter leaks into the PSD. So it is better to avoid a filter at all. We subsequently developed a method to detect edge displacements without the use of a filter. This method considers the signal profile of a SEM by integrating an experimental image of lines in the direction of the edges. The signal profile of an isolated edge is modeled as two merged Gaussians. This signal profile is then fitted against the raw (unfiltered) data of the edge pattern using an interior trust-region-reflective minimization procedure. This gives the edge displacements without the use of a filter and a filter-free version of the discrete PSD is obtained. The determination of edge displacements without the use of a filter, enables us to study how much noise is acceptable and still determine LER. To answer this question we generate random lines using the model of Palasantzas and the algorithm of Thorsos. This gives random generated edge displacements for typical values of experimental lines for the parameters of the model: 2 μm long lines (256 pixels), a correlation length ξ of 25 nm and a roughness exponent of 0.75. A noise-free top-down SEM-like image of lines is created by shifting the profile signal according to the random generated edge displacements. The image is further processed by adding Poisson-distributed noise. We consider three noise cases where the average electron density is about 2, 20 and 200 electrons per pixel. This corresponds to a charge density of (in respective order) 10 μC/cm2, 100 μC/cm2 and 1000 μC/cm2. The edge displacements of the random generated images are determined using our new

  7. Multiscale characterization of pore spaces using multifractals analysis of scanning electronic microscopy images of carbonates

    Directory of Open Access Journals (Sweden)

    M. S. Jouini

    2011-12-01

    Full Text Available Pore spaces heterogeneity in carbonates rocks has long been identified as an important factor impacting reservoir productivity. In this paper, we study the heterogeneity of carbonate rocks pore spaces based on the image analysis of scanning electron microscopy (SEM data acquired at various magnifications. Sixty images of twelve carbonate samples from a reservoir in the Middle East were analyzed. First, pore spaces were extracted from SEM images using a segmentation technique based on watershed algorithm. Pores geometries revealed a multifractal behavior at various magnifications from 800x to 12 000x. In addition, the singularity spectrum provided quantitative values that describe the degree of heterogeneity in the carbonates samples. Moreover, for the majority of the analyzed samples, we found low variations (around 5% in the multifractal dimensions for magnifications between 1700x and 12 000x. Finally, these results demonstrate that multifractal analysis could be an appropriate tool for characterizing quantitatively the heterogeneity of carbonate pore spaces geometries. However, our findings show that magnification has an impact on multifractal dimensions, revealing the limit of applicability of multifractal descriptions for these natural structures.

  8. Electron Paramagnetic Resonance pO2 Image Tumor Oxygen-Guided Radiation Therapy Optimization.

    Science.gov (United States)

    Epel, Boris; Maggio, Matt; Pelizzari, Charles; Halpern, Howard J

    2017-01-01

    Modern standards for radiation treatment do not take into account tumor oxygenation for radiation treatment planning. Strong correlation between tumor oxygenation and radiation treatment success suggests that oxygen-guided radiation therapy (OGRT) may be a promising enhancement of cancer radiation treatment. We have developed an OGRT protocol for rodents. Electron paramagnetic resonance (EPR) imaging is used for recording oxygen maps with high spatial resolution and excellent accuracy better than 1 torr. Radiation is delivered with an animal intensity modulated radiation therapy (IMRT) XRAD225Cx micro-CT/ therapy system. The radiation plan is delivered in two steps. First, a uniform 15% tumor control dose (TCD 15 ) is delivered to the whole tumor. In the second step, an additional booster dose amounting to the difference between TCD 98 and TCD 15 is delivered to radio-resistant, hypoxic tumor regions. Delivery of the booster dose is performed using a multiport conformal beam protocol. For radiation beam shaping we used individual radiation blocks 3D-printed from tungsten infused ABS polymer. Calculation of beam geometry and the production of blocks is performed next to the EPR imager, immediately after oxygen imaging. Preliminary results demonstrate the sub-millimeter precision of the radiation delivery and high dose accuracy. The efficacy of the radiation treatment is currently being tested on syngeneic FSa fibrosarcoma tumors grown in the legs of C3H mice.

  9. Imaging the He2 quantum halo state using a free electron laser

    Science.gov (United States)

    Zeller, Stefan; Kunitski, Maksim; Voigtsberger, Jörg; Kalinin, Anton; Schottelius, Alexander; Schober, Carl; Waitz, Markus; Sann, Hendrik; Hartung, Alexander; Bauer, Tobias; Pitzer, Martin; Trinter, Florian; Goihl, Christoph; Janke, Christian; Richter, Martin; Kastirke, Gregor; Weller, Miriam; Czasch, Achim; Kitzler, Markus; Braune, Markus; Grisenti, Robert E.; Schöllkopf, Wieland; Schmidt, Lothar Ph. H.; Schöffler, Markus S.; Williams, Joshua B.; Jahnke, Till; Dörner, Reinhard

    2016-12-01

    Quantum tunneling is a ubiquitous phenomenon in nature and crucial for many technological applications. It allows quantum particles to reach regions in space which are energetically not accessible according to classical mechanics. In this “tunneling region,” the particle density is known to decay exponentially. This behavior is universal across all energy scales from nuclear physics to chemistry and solid state systems. Although typically only a small fraction of a particle wavefunction extends into the tunneling region, we present here an extreme quantum system: a gigantic molecule consisting of two helium atoms, with an 80% probability that its two nuclei will be found in this classical forbidden region. This circumstance allows us to directly image the exponentially decaying density of a tunneling particle, which we achieved for over two orders of magnitude. Imaging a tunneling particle shows one of the few features of our world that is truly universal: the probability to find one of the constituents of bound matter far away is never zero but decreases exponentially. The results were obtained by Coulomb explosion imaging using a free electron laser and furthermore yielded He2’s binding energy of 151.9±13.3151.9±13.3 neV, which is in agreement with most recent calculations.

  10. Analysis of interfraction and intrafraction variation during tangential breast irradiation with an electronic portal imaging device

    International Nuclear Information System (INIS)

    Smith, Ryan P.; Bloch, Peter; Harris, Eleanor E.; McDonough, James; Sarkar, Abhirup; Kassaee, Alireza; Avery, Steven; Solin, Lawrence J.

    2005-01-01

    Purpose: To evaluate the daily setup variation and the anatomic movement of the heart and lungs during breast irradiation with tangential photon beams, as measured with an electronic portal imaging device. Methods and materials: Analysis of 1,709 portal images determined changes in the radiation field during a treatment course in 8 patients. Values obtained for every image included central lung distance (CLD) and area of lung and heart within the irradiated field. The data from these measurements were used to evaluate variation from setup between treatment days and motion due to respiration and/or patient movement during treatment delivery. Results: The effect of respiratory motion and movement during treatment was minimal: the maximum range in CLD for any patient on any day was 0.25 cm. The variation caused by day-to-day setup variation was greater, with CLD values for patients ranging from 0.59 cm to 2.94 cm. Similar findings were found for heart and lung areas. Conclusions: There is very little change in CLD and corresponding lung and heart area during individual radiation treatment fractions in breast tangential fields, compared with a relatively greater amount of variation that occurs between days

  11. Synchrotron Bragg diffraction imaging characterization of synthetic diamond crystals for optical and electronic power device applications.

    Science.gov (United States)

    Tran Thi, Thu Nhi; Morse, J; Caliste, D; Fernandez, B; Eon, D; Härtwig, J; Barbay, C; Mer-Calfati, C; Tranchant, N; Arnault, J C; Lafford, T A; Baruchel, J

    2017-04-01

    Bragg diffraction imaging enables the quality of synthetic single-crystal diamond substrates and their overgrown, mostly doped, diamond layers to be characterized. This is very important for improving diamond-based devices produced for X-ray optics and power electronics applications. The usual first step for this characterization is white-beam X-ray diffraction topography, which is a simple and fast method to identify the extended defects (dislocations, growth sectors, boundaries, stacking faults, overall curvature etc. ) within the crystal. This allows easy and quick comparison of the crystal quality of diamond plates available from various commercial suppliers. When needed, rocking curve imaging (RCI) is also employed, which is the quantitative counterpart of monochromatic Bragg diffraction imaging. RCI enables the local determination of both the effective misorientation, which results from lattice parameter variation and the local lattice tilt, and the local Bragg position. Maps derived from these parameters are used to measure the magnitude of the distortions associated with polishing damage and the depth of this damage within the volume of the crystal. For overgrown layers, these maps also reveal the distortion induced by the incorporation of impurities such as boron, or the lattice parameter variations associated with the presence of growth-incorporated nitrogen. These techniques are described, and their capabilities for studying the quality of diamond substrates and overgrown layers, and the surface damage caused by mechanical polishing, are illustrated by examples.

  12. Theoretical analysis and experimental evaluation of a CsI(Tl) based electronic portal imaging system

    International Nuclear Information System (INIS)

    Sawant, Amit; Zeman, Herbert; Samant, Sanjiv; Lovhoiden, Gunnar; Weinberg, Brent; DiBianca, Frank

    2002-01-01

    This article discusses the design and analysis of a portal imaging system based on a thick transparent scintillator. A theoretical analysis using Monte Carlo simulation was performed to calculate the x-ray quantum detection efficiency (QDE), signal to noise ratio (SNR) and the zero frequency detective quantum efficiency [DQE(0)] of the system. A prototype electronic portal imaging device (EPID) was built, using a 12.7 mm thick, 20.32 cm diameter, CsI(Tl) scintillator, coupled to a liquid nitrogen cooled CCD TV camera. The system geometry of the prototype EPID was optimized to achieve high spatial resolution. The experimental evaluation of the prototype EPID involved the determination of contrast resolution, depth of focus, light scatter and mirror glare. Images of humanoid and contrast detail phantoms were acquired using the prototype EPID and were compared with those obtained using conventional and high contrast portal film and a commercial EPID. A theoretical analysis was also carried out for a proposed full field of view system using a large area, thinned CCD camera and a 12.7 mm thick CsI(Tl) crystal. Results indicate that this proposed design could achieve DQE(0) levels up to 11%, due to its order of magnitude higher QDE compared to phosphor screen-metal plate based EPID designs, as well as significantly higher light collection compared to conventional TV camera based systems

  13. Ultrafast coherent diffractive imaging of nanoparticles using X-ray free-electron laser radiation

    International Nuclear Information System (INIS)

    Kassemeyer, Stephan

    2014-01-01

    Coherent diffractive imaging with X-ray free-electron lasers (X-FEL) promises high-resolution structure determination of single microscopic particles without the need for crystallization. The diffraction signal of small samples can be very weak, a difficulty that can not be countered by merely increasing the number of photons because the sample would be damaged by a high absorbed radiation dose. Traditional X-ray crystallography avoids this problem by bringing many sample particles into a periodic arrangement, which amplifies the individual signals while distributing the absorbed dose. Depending on the sample, however, crystallization can be very difficult or even impossible. This thesis presents algorithms for a new imaging approach using X-FEL radiation that works with single, non-crystalline sample particles. X-FELs can deliver X-rays with a peak brilliance many orders of magnitude higher than conventional X-ray sources, compensating for their weak interaction cross sections. At the same time, FELs can produce ultra-short pulses down to a few femtoseconds. In this way it is possible to perform ultra-fast imaging, essentially ''freezing'' the atomic positions in time and terminating the imaging process before the sample is destroyed by the absorbed radiation. This thesis primarily focuses on the three-dimensional reconstruction of single (and not necessarily crystalline) particles using coherent diffractive imaging at X-FELs: in order to extract three-dimensional information from scattering data, two-dimensional diffraction patterns from many different viewing angles must be combined. Therefore, the diffraction signal of many identical sample copies in random orientations is measured. The main result of this work is a globally optimal algorithm that can recover the sample orientations solely based on the diffraction signal, enabling three-dimensional imaging for arbitrary samples. The problem of finding three-dimensional orientations is

  14. Observer variability when evaluating patient movement from electronic portal images of pelvic radiotherapy fields

    International Nuclear Information System (INIS)

    Geraint Lewis, D.; Ryan, Karen R.; Smith, Cyril W.

    2005-01-01

    Background and purpose: A study has been performed to evaluate inter-observer variability when assessing pelvic patient movement using an electronic portal imaging device (EPID). Materials and methods: Four patient image sets were used with 3-6 portal images per set. The observer group consisted of nine radiographers with 3-18 months clinical EPID experience. The observers outlined bony landmarks on a digital simulator image and used matching software to evaluate field placement errors (FPEs) on each portal image relative to the reference simulator image. Data were evaluated statistically, using a two-component analysis of variance technique, to quantify both the inter-observer variability in evaluating FPEs and inter-fraction variability in patient position relative to the residuals of the analysis. Intra-observer variability was also estimated using four of the observers carrying out three sets of repeat readings. Results: Eight sets of variance data were analysed, based on FPEs in two orthogonal directions for each of the four patient image sets studied. Initial analysis showed that both inter-observer variation and inter-fraction-patient position variation were statistically significant (P<0.05) in seven of the eight cases evaluated. The averaged root-mean-square (RMS) deviation of the observers from the group mean was 1.1 mm, with a maximum deviation of 5.0 mm recorded for an individual observer. After additional training and re-testing of two of the observers who recorded the largest deviations from the group mean, a subsequent analysis showed the inter-observer variability for the group to be significant in only three of the eight cases, with averaged RMS deviation reduced to 0.5 mm, with a maximum deviation of 2.7 mm. The intra-observer variability was 0.5 mm, averaged over the four observers tested. Conclusions: We have developed a quantitative approach to evaluate inter-observer variability in terms of its statistical significance compared to inter

  15. Development of an IMRT quality assurance program using an amorphous silicon electronic portal imaging device

    International Nuclear Information System (INIS)

    Hunt, P.; Oliver, L.; Mallik, A.

    2000-01-01

    Full text: Quality Assurance (QA) for an intensity modulated radiotherapy (IMRT) megavoltage beam is a complex task. The positional accuracy of the MLC; its radiation leakage; the overall distribution of the dose delivered as compared to the treatment plan and; the accuracy of the calculated monitor units to deliver this dose, are all important parameters to clinically monitor. We are presently assessing the Varian version 6 software package with CadPlan, Helios with IMRT and inverse planning, VARiS Vision and the linear accelerator DMLC controller. Whilst conventional QA tools such as ionisation chamber and film measurements are used, these methods are inconvenient for directly monitoring an IMRT patient treatment. Varian Medical Systems has developed an improved electronic portal imaging device (EPID) with an amorphous silicon (a-Si) detector array. The A-Si has a sensitive area of 40x30cm and an improved image resolution of 512x384 pixels. Images are recorded at approximately 7-10 frames per second for an exposure rate of 100-600 MU/minute. Although the A-Si was designed as an EPID for a static treatment field, this new device could be a valuable IMRT QA tool for a range of different tests. Measurements taken on the RNSH and Varian prototype A-Si EPI devices showed a linear dose response for 6-18MeV X-ray energy. In addition to the Varian IAS2 internal software handlers, we have developed some image data handling programs to view and analyse these images in more detail. The software is primarily used to view the images; measure the reading in a region of interest or profile; or merge, overlay, add or subtract images during the analysis. The small pixel resolution provides a reliable, highly accurate means of measuring beam size, leaf position, MLC radiation leakage or profile intensity curves with a positional accuracy of 0.8mm. The images produced by an IMRT exposure is clearly discernible and appears consistent with the result expected. Step wedge images

  16. A Picture is Worth 1,000 Words. The Use of Clinical Images in Electronic Medical Records.

    Science.gov (United States)

    Ai, Angela C; Maloney, Francine L; Hickman, Thu-Trang; Wilcox, Allison R; Ramelson, Harley; Wright, Adam

    2017-07-12

    To understand how clinicians utilize image uploading tools in a home grown electronic health records (EHR) system. A content analysis of patient notes containing non-radiological images from the EHR was conducted. Images from 4,000 random notes from July 1, 2009 - June 30, 2010 were reviewed and manually coded. Codes were assigned to four properties of the image: (1) image type, (2) role of image uploader (e.g. MD, NP, PA, RN), (3) practice type (e.g. internal medicine, dermatology, ophthalmology), and (4) image subject. 3,815 images from image-containing notes stored in the EHR were reviewed and manually coded. Of those images, 32.8% were clinical and 66.2% were non-clinical. The most common types of the clinical images were photographs (38.0%), diagrams (19.1%), and scanned documents (14.4%). MDs uploaded 67.9% of clinical images, followed by RNs with 10.2%, and genetic counselors with 6.8%. Dermatology (34.9%), ophthalmology (16.1%), and general surgery (10.8%) uploaded the most clinical images. The content of clinical images referencing body parts varied, with 49.8% of those images focusing on the head and neck region, 15.3% focusing on the thorax, and 13.8% focusing on the lower extremities. The diversity of image types, content, and uploaders within a home grown EHR system reflected the versatility and importance of the image uploading tool. Understanding how users utilize image uploading tools in a clinical setting highlights important considerations for designing better EHR tools and the importance of interoperability between EHR systems and other health technology.

  17. Measurement of the electron and ion temperatures by the x-ray imaging crystal spectrometer on joint Texas experimental tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Yan, W.; Chen, Z. Y., E-mail: zychen@hust.edu.cn; Huang, D. W.; Tong, R. H.; Wang, S. Y.; Wei, Y. N.; Ma, T. K.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Jin, W. [Center of Interface Dynamics for Sustainability, China Academy of Engineering Physics, Chengdu, Sichuan 610200 (China); Lee, S. G. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Shi, Y. J. [Department of Nuclear Engineering, Seoul National University, Seoul 08826 (Korea, Republic of)

    2016-11-15

    An x-ray imaging crystal spectrometer has been developed on joint Texas experimental tokamak for the measurement of electron and ion temperatures from the K{sub α} spectra of helium-like argon and its satellite lines. A two-dimensional multi-wire proportional counter has been applied to detect the spectra. The electron and ion temperatures have been obtained from the Voigt fitting with the spectra of helium-like argon ions. The profiles of electron and ion temperatures show the dependence on electron density in ohmic plasmas.

  18. An image-based skeletal dosimetry model for the ICRP reference newborn-internal electron sources

    International Nuclear Information System (INIS)

    Pafundi, Deanna; Lee, Choonsik; Bolch, Wesley; Rajon, Didier; Jokisch, Derek

    2010-01-01

    In this study, a comprehensive electron dosimetry model of newborn skeletal tissues is presented. The model is constructed using the University of Florida newborn hybrid phantom of Lee et al (2007 Phys. Med. Biol. 52 3309-33), the newborn skeletal tissue model of Pafundi et al (2009 Phys. Med. Biol. 54 4497-531) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow (surrogate tissue for hematopoietic stem cells), shallow marrow (surrogate tissue for osteoprogenitor cells) and unossified cartilage (surrogate tissue for chondrocytes). Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following source tissues: active marrow, trabecular bone (surfaces and volumes), cortical bone (surfaces and volumes) and cartilage. Transport results are reported as specific absorbed fractions according to the MIRD schema and are given as skeletal-averaged values in the paper with bone-specific values reported in both tabular and graphic format as electronic annexes (supplementary data). The method utilized in this work uniquely includes (1) explicit accounting for the finite size and shape of newborn ossification centers (spongiosa regions), (2) explicit accounting for active and shallow marrow dose from electron emissions in cortical bone as well as sites of unossified cartilage, (3) proper accounting of the distribution of trabecular and cortical volumes and surfaces in the newborn skeleton when considering mineral bone sources and (4) explicit consideration of the marrow cellularity changes for active marrow self-irradiation as applicable to radionuclide therapy of diseased marrow in the newborn child.

  19. An image-based skeletal dosimetry model for the ICRP reference newborn-internal electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Pafundi, Deanna; Lee, Choonsik; Bolch, Wesley [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL (United States); Rajon, Didier [Department of Neurosurgery, University of Florida, Gainesville, FL (United States); Jokisch, Derek [Department of Physics and Astronomy, Francis Marion University, Florence, SC (United States)], E-mail: wbolch@ufl.edu

    2010-04-07

    In this study, a comprehensive electron dosimetry model of newborn skeletal tissues is presented. The model is constructed using the University of Florida newborn hybrid phantom of Lee et al (2007 Phys. Med. Biol. 52 3309-33), the newborn skeletal tissue model of Pafundi et al (2009 Phys. Med. Biol. 54 4497-531) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow (surrogate tissue for hematopoietic stem cells), shallow marrow (surrogate tissue for osteoprogenitor cells) and unossified cartilage (surrogate tissue for chondrocytes). Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following source tissues: active marrow, trabecular bone (surfaces and volumes), cortical bone (surfaces and volumes) and cartilage. Transport results are reported as specific absorbed fractions according to the MIRD schema and are given as skeletal-averaged values in the paper with bone-specific values reported in both tabular and graphic format as electronic annexes (supplementary data). The method utilized in this work uniquely includes (1) explicit accounting for the finite size and shape of newborn ossification centers (spongiosa regions), (2) explicit accounting for active and shallow marrow dose from electron emissions in cortical bone as well as sites of unossified cartilage, (3) proper accounting of the distribution of trabecular and cortical volumes and surfaces in the newborn skeleton when considering mineral bone sources and (4) explicit consideration of the marrow cellularity changes for active marrow self-irradiation as applicable to radionuclide therapy of diseased marrow in the newborn child.

  20. Characterization of a high-elbow, fluoroscopic electronic portal imaging device for portal dosimetry

    International Nuclear Information System (INIS)

    Boer, J.C.J. de; Visser, A.G.

    2000-01-01

    The application of a newly developed fluoroscopic (CCD-camera based) electronic portal imaging device (EPID) in portal dosimetry is investigated. A description of the EPID response to dose is presented in terms of stability, linearity and optical cross-talk inside the mechanical structure. The EPID has a relatively large distance (41 cm on-axis) between the fluorescent screen and the mirror (high-elbow), which results in cross-talk with properties quite different from that of the low-elbow fluoroscopic EPIDs that have been studied in the literature. In contrast with low-elbow systems, the maximum cross-talk is observed for points of the fluorescent screen that have the largest distance to the mirror, which is explained from the geometry of the system. An algorithm to convert the images of the EPID into portal dose images (PDIs) is presented. The correction applied for cross-talk is a position-dependent additive operation on the EPID image pixel values, with a magnitude that depends on a calculated effective field width. Deconvolution with a point spread function, as applied for low-elbow systems, is not required. For a 25 MV beam, EPID PDIs and ionization chamber measurements in the EPID detector plane were obtained behind an anthropomorphic phantom and a homogeneous absorber for various field shapes. The difference in absolute dose between the EPID and ionization chamber measurements, averaged over the four test fields presented in this paper, was 0.1±0.5% (1 SD) over the entire irradiation field, with no deviation larger than 2%. (author)

  1. A Monte Carlo calculation model of electronic portal imaging device for transit dosimetry through heterogeneous media

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jihyung; Jung, Jae Won, E-mail: jungj@ecu.edu [Department of Physics, East Carolina University, Greenville, North Carolina 27858 (United States); Kim, Jong Oh [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15232 (United States); Yeo, Inhwan [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92354 (United States)

    2016-05-15

    Purpose: To develop and evaluate a fast Monte Carlo (MC) dose calculation model of electronic portal imaging device (EPID) based on its effective atomic number modeling in the XVMC code. Methods: A previously developed EPID model, based on the XVMC code by density scaling of EPID structures, was modified by additionally considering effective atomic number (Z{sub eff}) of each structure and adopting a phase space file from the EGSnrc code. The model was tested under various homogeneous and heterogeneous phantoms and field sizes by comparing the calculations in the model with measurements in EPID. In order to better evaluate the model, the performance of the XVMC code was separately tested by comparing calculated dose to water with ion chamber (IC) array measurement in the plane of EPID. Results: In the EPID plane, calculated dose to water by the code showed agreement with IC measurements within 1.8%. The difference was averaged across the in-field regions of the acquired profiles for all field sizes and phantoms. The maximum point difference was 2.8%, affected by proximity of the maximum points to penumbra and MC noise. The EPID model showed agreement with measured EPID images within 1.3%. The maximum point difference was 1.9%. The difference dropped from the higher value of the code by employing the calibration that is dependent on field sizes and thicknesses for the conversion of calculated images to measured images. Thanks to the Z{sub eff} correction, the EPID model showed a linear trend of the calibration factors unlike those of the density-only-scaled model. The phase space file from the EGSnrc code sharpened penumbra profiles significantly, improving agreement of calculated profiles with measured profiles. Conclusions: Demonstrating high accuracy, the EPID model with the associated calibration system may be used for in vivo dosimetry of radiation therapy. Through this study, a MC model of EPID has been developed, and their performance has been rigorously

  2. Phase contrast scanning transmission electron microscopy imaging of light and heavy atoms at the limit of contrast and resolution.

    Science.gov (United States)

    Yücelen, Emrah; Lazić, Ivan; Bosch, Eric G T

    2018-02-08

    Using state of the art scanning transmission electron microscopy (STEM) it is nowadays possible to directly image single atomic columns at sub-Å resolution. In standard (high angle) annular dark field STEM ((HA)ADF-STEM), however, light elements are usually invisible when imaged together with heavier elements in one image. Here we demonstrate the capability of the recently introduced Integrated Differential Phase Contrast STEM (iDPC-STEM) technique to image both light and heavy atoms in a thin sample at sub-Å resolution. We use the technique to resolve both the Gallium and Nitrogen dumbbells in a GaN crystal in [[Formula: see text

  3. Use of a line-pair resolution phantom for comprehensive quality assurance of electronic portal imaging devices based on fundamental imaging metrics

    International Nuclear Information System (INIS)

    Gopal, Arun; Samant, Sanjiv S.

    2009-01-01

    Image guided radiation therapy solutions based on megavoltage computed tomography (MVCT) involve the extension of electronic portal imaging devices (EPIDs) from their traditional role of weekly localization imaging and planar dose mapping to volumetric imaging for 3D setup and dose verification. To sustain the potential advantages of MVCT, EPIDs are required to provide improved levels of portal image quality. Therefore, it is vital that the performance of EPIDs in clinical use is maintained at an optimal level through regular and rigorous quality assurance (QA). Traditionally, portal imaging QA has been carried out by imaging calibrated line-pair and contrast resolution phantoms and obtaining arbitrarily defined QA indices that are usually dependent on imaging conditions and merely indicate relative trends in imaging performance. They are not adequately sensitive to all aspects of image quality unlike fundamental imaging metrics such as the modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) that are widely used to characterize detector performance in radiographic imaging and would be ideal for QA purposes. However, due to the difficulty of performing conventional MTF measurements, they have not been used for routine clinical QA. The authors present a simple and quick QA methodology based on obtaining the MTF, NPS, and DQE of a megavoltage imager by imaging standard open fields and a bar-pattern QA phantom containing 2 mm thick tungsten line-pair bar resolution targets. Our bar-pattern based MTF measurement features a novel zero-frequency normalization scheme that eliminates normalization errors typically associated with traditional bar-pattern measurements at megavoltage x-ray energies. The bar-pattern QA phantom and open-field images are used in conjunction with an automated image analysis algorithm that quickly computes the MTF, NPS, and DQE of an EPID system. Our approach combines the fundamental advantages of

  4. Measurement of filling factor 5/2 quasiparticle interference with observation of charge e/4 and e/2 period oscillations.

    Science.gov (United States)

    Willett, R L; Pfeiffer, L N; West, K W

    2009-06-02

    A standing problem in low-dimensional electron systems is the nature of the 5/2 fractional quantum Hall (FQH) state: Its elementary excitations are a focus for both elucidating the state's properties and as candidates in methods to perform topological quantum computation. Interferometric devices may be used to manipulate and measure quantum Hall edge excitations. Here we use a small-area edge state interferometer designed to observe quasiparticle interference effects. Oscillations consistent in detail with the Aharonov-Bohm effect are observed for integer quantum Hall and FQH states (filling factors nu = 2, 5/3, and 7/3) with periods corresponding to their respective charges and magnetic field positions. With these factors as charge calibrations, periodic transmission through the device consistent with quasiparticle charge e/4 is observed at nu = 5/2 and at lowest temperatures. The principal finding of this work is that, in addition to these e/4 oscillations, periodic structures corresponding to e/2 are also observed at 5/2 nu and at lowest temperatures. Properties of the e/4 and e/2 oscillations are examined with the device sensitivity sufficient to observe temperature evolution of the 5/2 quasiparticle interference. In the model of quasiparticle interference, this presence of an effective e/2 period may empirically reflect an e/2 quasiparticle charge or may reflect multiple passes of the e/4 quasiparticle around the interferometer. These results are discussed within a picture of e/4 quasiparticle excitations potentially possessing non-Abelian statistics. These studies demonstrate the capacity to perform interferometry on 5/2 excitations and reveal properties important for understanding this state and its excitations.

  5. The Advanced Gamma-ray Imaging System (AGIS): Camera Electronics Designs

    Science.gov (United States)

    Tajima, H.; Buckley, J.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Holder, J.; Horan, D.; Krawczynski, H.; Ong, R.; Swordy, S.; Wagner, R.; Williams, D.

    2008-04-01

    AGIS, a next generation of atmospheric Cherenkov telescope arrays, aims to achieve a sensitivity level of a milliCrab for gamma-ray observations in the energy band of 40 GeV to 100 TeV. Such improvement requires cost reduction of individual components with high reliability in order to equip the order of 100 telescopes necessary to achieve the sensitivity goal. We are exploring several design concepts to reduce the cost of camera electronics while improving their performance. These design concepts include systems based on multi-channel waveform sampling ASIC optimized for AGIS, a system based on IIT (image intensifier tube) for large channel (order of 1 million channels) readout as well as a multiplexed FADC system based on the current VERITAS readout design. Here we present trade-off in the studies of these design concepts.

  6. Time-resolved Chemical Imaging of Molecules by High-order Harmonics and Ultrashort Rescattering Electrons

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chii Dong [Kansas State Univ., Manhattan, KS (United States)

    2016-03-21

    Directly monitoring atomic motion during a molecular transformation with atomic-scale spatio-temporal resolution is a frontier of ultrafast optical science and physical chemistry. Here we provide the foundation for a new imaging method, fixed-angle broadband laser-induced electron scattering, based on structural retrieval by direct one-dimensional Fourier transform of a photoelectron energy distribution observed along the polarization direction of an intense ultrafast light pulse. The approach exploits the scattering of a broadband wave packet created by strong-field tunnel ionization to self-interrogate the molecular structure with picometre spatial resolution and bond specificity. With its inherent femtosecond resolution, combining our technique with molecular alignment can, in principle, provide the basis for time-resolved tomography for multi-dimensional transient structural determination.

  7. Data acquisition and processing system of the electron cyclotron emission imaging system of the KSTAR tokamak

    International Nuclear Information System (INIS)

    Kim, J. B.; Lee, W.; Yun, G. S.; Park, H. K.; Domier, C. W.; Luhmann, N. C. Jr.

    2010-01-01

    A new innovative electron cyclotron emission imaging (ECEI) diagnostic system for the Korean Superconducting Tokamak Advanced Research (KSTAR) produces a large amount of data. The design of the data acquisition and processing system of the ECEI diagnostic system should consider covering the large data production and flow. The system design is based on the layered structure scalable to the future extension to accommodate increasing data demands. Software architecture that allows a web-based monitoring of the operation status, remote experiment, and data analysis is discussed. The operating software will help machine operators and users validate the acquired data promptly, prepare next discharge, and enhance the experiment performance and data analysis in a distributed environment.

  8. Using an electronic portal imaging device for exit dose measurements in radiotherapy

    International Nuclear Information System (INIS)

    Ganowicz, M.; Wozniak, B.; Bekman, A.; Maniakowski, Z.

    2003-01-01

    To present a method of determining the exit dose with the use of an electronic portal imaging device (EPID). The device used was the Portal Vision LC250 (Varian). The EPID signals on the central beam axis have been related to the exit dose. The exit dose measurements were performed with the ionisation chamber in the slab phantom at the distance of dose maximum from the exit surface of the phantom. EPID reading was investigated as a function of field size, phantom thickness and source-detector distance. The relation between dose rate and the EPID reading is described with empirical functions applicable to the obtained data. The exit dose is calculated from the EPID reading as a product of the calibration factor and appropriate correction factors. The determination of the exit dose rate from the EPID signal requires the knowledge of many parameters and earlier determination of essential characteristics. (author)

  9. Modular focusing ring imaging Cherenkov detector for electron-ion collider experiments

    Science.gov (United States)

    Wong, C. P.; Alfred, M.; Allison, L.; Awadi, M.; Azmoun, B.; Barbosa, F.; Barion, L.; Bennett, J.; Brooks, W.; Butler, C.; Cao, T.; Chiu, M.; Cisbani, E.; Contalbrigo, M.; Datta, A.; Del Dotto, A.; Demarteau, M.; Durham, J. M.; Dzhygadlo, R.; Elder, T.; Fields, D.; Furletova, Y.; Gleason, C.; Grosse-Perdekamp, M.; Harris, J.; Haseler, T. O. S.; He, X.; van Hecke, H.; Horn, T.; Hruschka, A.; Huang, J.; Hyde, C.; Ilieva, Y.; Kalicy, G.; Kimball, M.; Kistenev, E.; Kulinich, Y.; Liu, M.; Majka, R.; McKisson, J.; Mendez, R.; Nadel-Turonski, P.; Park, K.; Peters, K.; Rao, T.; Pisani, R.; Qiang, Y.; Rescia, S.; Rossi, P.; Sarajlic, O.; Sarsour, M.; Schwarz, C.; Schwiening, J.; da Silva, C. L.; Smirnov, N.; Stien, H. D.; Stevens, J.; Sukhanov, A.; Syed, S.; Tate, A. C.; Toh, J.; Towell, C. L.; Towell, R. S.; Tsang, T.; Turisini, M.; Wagner, R.; Wang, J.; Woody, C.; Xi, W.; Xie, J.; Zhao, Z. W.; Zihlmann, B.; Zorn, C.

    2017-11-01

    A powerful new electron-ioncollider (EIC) has been recommended in the 2015 Long Range Plan for Nuclear Science for probing the partonic structure inside nucleons and nuclei with unprecedented precision and versatility [1]. EIC detectors are currently under development [2], all of which require hadron identification over a broad kinematic range. A prototype ring imaging Cherenkov detector has been developed for hadron identification in the momentum range from 3 GeV/c to 10 GeV/c. The key feature of this new detector is a compact and modular design, achieved by using aerogel as radiator and a Fresnel lens for ring focusing. In this paper, the results from a beam test of a prototype device at Fermilab are reported.

  10. Impact of measuring electron tracks in high-resolution scientific charge-coupled devices within Compton imaging systems

    International Nuclear Information System (INIS)

    Chivers, D.H.; Coffer, A.; Plimley, B.; Vetter, K.

    2011-01-01

    We have implemented benchmarked models to determine the gain in sensitivity of electron-tracking based Compton imaging relative to conventional Compton imaging by the use of high-resolution scientific charge-coupled devices (CCD). These models are based on the recently demonstrated ability of electron-tracking based Compton imaging by using fully depleted scientific CCDs. Here we evaluate the gain in sensitivity by employing Monte Carlo simulations in combination with advanced charge transport models to calculate two-dimensional charge distributions corresponding to experimentally obtained tracks. In order to reconstruct the angle of the incident γ-ray, a trajectory determination algorithm was used on each track and integrated into a back-projection routine utilizing a geodesic-vertex ray tracing technique. Analysis was performed for incident γ-ray energies of 662 keV and results show an increase in sensitivity consistent with tracking of the Compton electron to approximately ±30 o .

  11. Imaging Magnetic Vortices Dynamics Using Lorentz Electron Microscopy with GHz Excitations

    Science.gov (United States)

    Zhu, Yimei

    2015-03-01

    Magnetic vortices in thin films are naturally formed spiral spin configurations with a core polarization pointing out of the film plane. They typically represent ground states with high structural and thermal stability as well as four different chirality-polarity combinations, offering great promise in the development of spin-based devices. For applications to spin oscillators, non-volatile memory and logic devices, the fundamental understanding and precise control of vortex excitations and dynamic switching behavior are essential. The compact dimensionality and fast spin dynamics set grand challenges for direct imaging technologies. Recently, we have developed a unique method to directly visualize the dynamic magnetic vortex motion using advanced Lorentz electron microscopy combined with GHz electronic excitations. It enables us to map the orbit of a magnetic vortex core in a permalloy square with modality. Our approach is complementary to X-ray magnetic circular dichroism and is of general interest to the magnetism community as it paves a way to study fundamental spin phenomena with unprecedented resolution and accuracy. Collaborations with S.D. Pollard, J.F. Pulecio, D.A. Arena and K.S. Buchanan are acknowledged. Work supported by DOE-BES, Material Sciences and Engineering Division, under Contract No. DE-AC02-98CH10886.

  12. Time-resolved magnetic imaging in an aberration-corrected, energy-filtered photoemission electron microscope

    International Nuclear Information System (INIS)

    Nickel, F.; Gottlob, D.M.; Krug, I.P.; Doganay, H.; Cramm, S.; Kaiser, A.M.; Lin, G.; Makarov, D.; Schmidt, O.G.

    2013-01-01

    We report on the implementation and usage of a synchrotron-based time-resolving operation mode in an aberration-corrected, energy-filtered photoemission electron microscope. The setup consists of a new type of sample holder, which enables fast magnetization reversal of the sample by sub-ns pulses of up to 10 mT. Within the sample holder current pulses are generated by a fast avalanche photo diode and transformed into magnetic fields by means of a microstrip line. For more efficient use of the synchrotron time structure, we developed an electrostatic deflection gating mechanism capable of beam blanking within a few nanoseconds. This allows us to operate the setup in the hybrid bunch mode of the storage ring facility, selecting one or several bright singular light pulses which are temporally well-separated from the normal high-intensity multibunch pulse pattern. - Highlights: • A new time-resolving operation mode in photoemission electron microscopy is shown. • Our setup works within an energy-filtered, aberration-corrected PEEM. • A new gating system for bunch selection using synchrotron radiation is developed. • An alternative magnetic excitation system is developed. • First tr-imaging using an energy-filtered, aberration-corrected PEEM is shown

  13. YBCO hot-electron bolometers dedicated to THz detection and imaging: Embedding issues

    International Nuclear Information System (INIS)

    Aurino, M; Tuerer, I; Martinez, A; Gensbittel, A; Degardin, A F; Kreisler, A J

    2010-01-01

    High-T c hot-electron bolometers (HEB) are an interesting alternative to other superconducting heterodyne mixers in the terahertz frequency range because of low-cost cooling investment, ultra-wide instantaneous bandwidth and low intrinsic noise level, even at 80 K. A technological process to fabricate stacked yttrium-based (YBCO) / praseodymium-based (PBCO) ultra-thin films (in the 15 to 40 nm thickness range) etched to form 0.5 μm x 0.5 μm constrictions, elaborated on (100) MgO substrates, has been previously described. Ageing effects were also considered, with the consequence of increased electrical resistance, significant degradation of the regular THz response and no HEB mixing action. Electron and UV lithography steps are revisited here to realize HEB mixers based on nano-bridges covered by a log-periodic planar gold antenna, dedicated to the 1 to 7 THz range. Several measures have been attempted to reduce the conversion losses, mainly by considering the embedding issues related to the YBCO nano-bridge impedance matching to the antenna and the design of optimized intermediate frequency circuitry. Antenna simulations were performed and validated through experiments on scaled models at GHz frequencies. Electromagnetic coupling to the incoming radiation was also studied, including crosstalk between neighbour antennas forming a linear imaging array.

  14. Comments on advanced, time-resolved imaging techniques for free-electron laser (FEL) experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H.

    1992-01-01

    An extensive set of time-resolved imaging experiments has been performed on rf-linac driven free-electron lasers (FELs) over the past few years. These experiments have addressed both micropulse and macropulse timescales on both the charged-particle beam and the wiggler/undulator outputs (spontaneous emission and lasing). A brief review of first measurements on photoinjecter micropulse elongation, submacropulse phase slew in drive lasers, submacropulse wavelength shifts in lasers, etc. is presented. This is followed by discussions of new measurements of 35-MeV electron beam micropulse bunch length (<10 ps) using optical transition radiation, some of the first single bend synchrotron radiation beam profile measurements at gamma <80, and comments on the low-jitter synchroscan streak camera tuner. These techniques will be further developed on the 200-650 MeV linac test stand at the Advanced Photon Source (APS) in the next few years. Such techniques should be adaptable to many of the present FEL designs and to some aspects of the next generation of light sources.

  15. Comments on advanced, time-resolved imaging techniques for free-electron laser (FEL) experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H.

    1992-11-01

    An extensive set of time-resolved imaging experiments has been performed on rf-linac driven free-electron lasers (FELs) over the past few years. These experiments have addressed both micropulse and macropulse timescales on both the charged-particle beam and the wiggler/undulator outputs (spontaneous emission and lasing). A brief review of first measurements on photoinjecter micropulse elongation, submacropulse phase slew in drive lasers, submacropulse wavelength shifts in lasers, etc. is presented. This is followed by discussions of new measurements of 35-MeV electron beam micropulse bunch length (<10 ps) using optical transition radiation, some of the first single bend synchrotron radiation beam profile measurements at gamma <80, and comments on the low-jitter synchroscan streak camera tuner. These techniques will be further developed on the 200-650 MeV linac test stand at the Advanced Photon Source (APS) in the next few years. Such techniques should be adaptable to many of the present FEL designs and to some aspects of the next generation of light sources.

  16. A new gamma ray imaging diagnostic for runaway electron studies at DIII-D

    Science.gov (United States)

    Cooper, C. M.; Pace, D. C.; Eidietis, N. W.; Paz-Soldan, C.; Commaux, N.; Shiraki, D.; Hollmann, E. M.; Moyer, R. A.; Risov, V.

    2015-11-01

    A new Gamma Ray Imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at DIII-D. The diagnostic is sensitive to 0.5 - 50 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE dissipation from pellet injection. The GRI consists of a lead ``pinhole camera'' mounted on the midplane with 11x11 counter-current tangential chords 20 cm wide that span the vessel. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE Bremsstrahlung radiation. Detectors operate in current saturation mode at 10 MHz, or the flux is attenuated for Pulse Height Analysis (PHA) capable of discriminating up to ~10k pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. Work supported by the US DOE under DE-AC05-00OR22725, DE-FG02-07ER54917 & DE-FC02-04ER54698.

  17. Many-beam effects in electron microscope images of lattice defects

    International Nuclear Information System (INIS)

    Izui, Kazuhiko; Nishida, Takahiko; Furuno, Shigemi; Otsu, Hitoshi

    1974-01-01

    Multi-beam effects in electron microscopic images were investigated. A computation program was developed on the basis of a matrix theory of the multi-beam effects. The matrix theory for a perfect crystal and an imperfect crystal is described, and expression for absorption coefficient is presented. The amplitude of electron wave penetrating through lattice defects is expressed by using scattering matrices which correspond to crystal slices. Calculation of extinction distance was performed, and compared with experimental results. In case of systematic reflection, the difference between two beams and from four to eight beams approximation was small, while a large effect was seen in case of accidental reflection. The intensity profile of bend contour was calculated for silicon and copper-aluminum alloy. Distance between submaxima becomes short with increase of thickness. The change in stacking fault fringes with diffraction condition was investigated. Samples were copper-aluminum alloy. Systematic behavior of the fringes was obtained, and the calculated results reproduced experimental ones. (Kato, T.)

  18. Parallel image-acquisition in continuous-wave electron paramagnetic resonance imaging with a surface coil array: Proof-of-concept experiments

    Science.gov (United States)

    Enomoto, Ayano; Hirata, Hiroshi

    2014-02-01

    This article describes a feasibility study of parallel image-acquisition using a two-channel surface coil array in continuous-wave electron paramagnetic resonance (CW-EPR) imaging. Parallel EPR imaging was performed by multiplexing of EPR detection in the frequency domain. The parallel acquisition system consists of two surface coil resonators and radiofrequency (RF) bridges for EPR detection. To demonstrate the feasibility of this method of parallel image-acquisition with a surface coil array, three-dimensional EPR imaging was carried out using a tube phantom. Technical issues in the multiplexing method of EPR detection were also clarified. We found that degradation in the signal-to-noise ratio due to the interference of RF carriers is a key problem to be solved.

  19. Differentiating gold nanorod samples using particle size and shape distributions from transmission electron microscope images

    Science.gov (United States)

    Grulke, Eric A.; Wu, Xiaochun; Ji, Yinglu; Buhr, Egbert; Yamamoto, Kazuhiro; Song, Nam Woong; Stefaniak, Aleksandr B.; Schwegler-Berry, Diane; Burchett, Woodrow W.; Lambert, Joshua; Stromberg, Arnold J.

    2018-04-01

    Size and shape distributions of gold nanorod samples are critical to their physico-chemical properties, especially their longitudinal surface plasmon resonance. This interlaboratory comparison study developed methods for measuring and evaluating size and shape distributions for gold nanorod samples using transmission electron microscopy (TEM) images. The objective was to determine whether two different samples, which had different performance attributes in their application, were different with respect to their size and/or shape descriptor distributions. Touching particles in the captured images were identified using a ruggedness shape descriptor. Nanorods could be distinguished from nanocubes using an elongational shape descriptor. A non-parametric statistical test showed that cumulative distributions of an elongational shape descriptor, that is, the aspect ratio, were statistically different between the two samples for all laboratories. While the scale parameters of size and shape distributions were similar for both samples, the width parameters of size and shape distributions were statistically different. This protocol fulfills an important need for a standardized approach to measure gold nanorod size and shape distributions for applications in which quantitative measurements and comparisons are important. Furthermore, the validated protocol workflow can be automated, thus providing consistent and rapid measurements of nanorod size and shape distributions for researchers, regulatory agencies, and industry.

  20. Examination of Scanning Electron Microscope and Computed Tomography Images of PICA

    Science.gov (United States)

    Lawson, John W.; Stackpoole, Margaret M.; Shklover, Valery

    2010-01-01

    Micrographs of PICA (Phenolic Impregnated Carbon Ablator) taken using a Scanning Electron Microscope (SEM) and 3D images taken with a Computed Tomography (CT) system are examined. PICA is a carbon fiber based composite (Fiberform ) with a phenolic polymer matrix. The micrographs are taken at different surface depths and at different magnifications in a sample after arc jet testing and show different levels of oxidative removal of the charred matrix (Figs 1 though 13). CT scans, courtesy of Xradia, Inc. of Concord CA, were captured for samples of virgin PICA, charred PICA and raw Fiberform (Fig. 14). We use these images to calculate the thermal conductivity (TC) of these materials using correlation function (CF) methods. CF methods give a mathematical description of how one material is embedded in another and is thus ideally suited for modeling composites like PICA. We will evaluate how the TC of the materials changes as a function of surface depth. This work is in collaboration with ETH-Zurich, which has expertise in high temperature materials and TC modeling (including CF methods).

  1. Frontend Receiver Electronics for High Frequency Monolithic CMUT-on-CMOS Imaging Arrays

    Science.gov (United States)

    Gurun, Gokce; Hasler, Paul; Degertekin, F. Levent

    2012-01-01

    This paper describes the design of CMOS receiver electronics for monolithic integration with capacitive micromachined ultrasonic transducer (CMUT) arrays for high-frequency intravascular ultrasound imaging. A custom 8-inch wafer is fabricated in a 0.35 μm two-poly, four-metal CMOS process and then CMUT arrays are built on top of the application specific integrated circuits (ASICs) on the wafer. We discuss advantages of the single-chip CMUT-on-CMOS approach in terms of receive sensitivity and SNR. Low-noise and high-gain design of a transimpedance amplifier (TIA) optimized for a forward-looking volumetric-imaging CMUT array element is discussed as a challenging design example. Amplifier gain, bandwidth, dynamic range and power consumption trade-offs are discussed in detail. With minimized parasitics provided by the CMUT-on-CMOS approach, the optimized TIA design achieves a 90 fA/√Hz input referred current noise, which is less than the thermal-mechanical noise of the CMUT element. We show successful system operation with a pulse-echo measurement. Transducer noise-dominated detection in immersion is also demonstrated through output noise spectrum measurement of the integrated system at different CMUT bias voltages. A noise figure of 1.8 dB is obtained in the designed CMUT bandwidth of 10 MHz to 20 MHz. PMID:21859585

  2. Front-end receiver electronics for high-frequency monolithic CMUT-on-CMOS imaging arrays.

    Science.gov (United States)

    Gurun, Gokce; Hasler, Paul; Degertekin, F

    2011-08-01

    This paper describes the design of CMOS receiver electronics for monolithic integration with capacitive micromachined ultrasonic transducer (CMUT) arrays for highfrequency intravascular ultrasound imaging. A custom 8-inch (20-cm) wafer is fabricated in a 0.35-μm two-poly, four-metal CMOS process and then CMUT arrays are built on top of the application specific integrated circuits (ASICs) on the wafer. We discuss advantages of the single-chip CMUT-on-CMOS approach in terms of receive sensitivity and SNR. Low-noise and high-gain design of a transimpedance amplifier (TIA) optimized for a forward-looking volumetric-imaging CMUT array element is discussed as a challenging design example. Amplifier gain, bandwidth, dynamic range, and power consumption trade-offs are discussed in detail. With minimized parasitics provided by the CMUT-on-CMOS approach, the optimized TIA design achieves a 90 fA/√Hz input-referred current noise, which is less than the thermal-mechanical noise of the CMUT element. We show successful system operation with a pulseecho measurement. Transducer-noise-dominated detection in immersion is also demonstrated through output noise spectrum measurement of the integrated system at different CMUT bias voltages. A noise figure of 1.8 dB is obtained in the designed CMUT bandwidth of 10 to 20 MHz.

  3. Assessment of a customised immobilisation system for head and neck IMRT using electronic portal imaging

    International Nuclear Information System (INIS)

    Humphreys, Mandy; Guerrero Urbano, M.Teressa; Mubata, Cefas; Miles, Elizabeth; Harrington, Kevin J.; Bidmead, Margaret; Nutting, Christopher M.

    2005-01-01

    Purpose: To evaluate set-up reproducibility of a cabulite shell and determine CTV-PTV margins for head and neck intensity-modulated-radiotherapy. Materials and methods: Twenty patients were entered into the study. A total of 354 anterior and lateral isocentric electronic portal images (EPIs) were compared to simulator reference images. Results: About 94% of all translational displacements were ≤3 mm, and 99% ≤5 mm. The overall systematic error was 0.9 mm (±1.0SD) in the Right-Left, 0.7 mm (±0.9SD) in the Superior-Inferior and -0.02 mm (±1.1SD) in the Anterior-Posterior directions. The corresponding SDs of the random errors were ±0.4, ±0.6 and ±0.7 mm. The estimated margins required from CTV-PTV were calculated according to the Van Herk formula was 2.9, 2.6 and 3.3 mm, respectively. Conclusions: This head and neck immobilisation system is of sufficient accuracy for its use with IMRT treatments and a 3 mm CTV-PTV margin has been adopted

  4. Spline-based image-to-volume registration for three-dimensional electron microscopy

    International Nuclear Information System (INIS)

    Jonic, S.; Sorzano, C.O.S.; Thevenaz, P.; El-Bez, C.; De Carlo, S.; Unser, M.

    2005-01-01

    This paper presents an algorithm based on a continuous framework for a posteriori angular and translational assignment in three-dimensional electron microscopy (3DEM) of single particles. Our algorithm can be used advantageously to refine the assignment of standard quantized-parameter methods by registering the images to a reference 3D particle model. We achieve the registration by employing a gradient-based iterative minimization of a least-squares measure of dissimilarity between an image and a projection of the volume in the Fourier transform (FT) domain. We compute the FT of the projection using the central-slice theorem (CST). To compute the gradient accurately, we take advantage of a cubic B-spline model of the data in the frequency domain. To improve the robustness of the algorithm, we weight the cost function in the FT domain and apply a 'mixed' strategy for the assignment based on the minimum value of the cost function at registration for several different initializations. We validate our algorithm in a fully controlled simulation environment. We show that the mixed strategy improves the assignment accuracy; on our data, the quality of the angular and translational assignment was better than 2 voxel (i.e., 6.54 A). We also test the performance of our algorithm on real EM data. We conclude that our algorithm outperforms a standard projection-matching refinement in terms of both consistency of 3D reconstructions and speed

  5. Investigation of image distortion due to MCP electronic readout misalignment and correction via customized GUI application

    Science.gov (United States)

    Vitucci, G.; Minniti, T.; Tremsin, A. S.; Kockelmann, W.; Gorini, G.

    2018-04-01

    The MCP-based neutron counting detector is a novel device that allows high spatial resolution and time-resolved neutron radiography and tomography with epithermal, thermal and cold neutrons. Time resolution is possible by the high readout speeds of ~ 1200 frames/sec, allowing high resolution event counting with relatively high rates without spatial resolution degradation due to event overlaps. The electronic readout is based on a Timepix sensor, a CMOS pixel readout chip developed at CERN. Currently, a geometry of a quad Timepix detector is used with an active format of 28 × 28 mm2 limited by the size of the Timepix quad (2 × 2 chips) readout. Measurements of a set of high-precision micrometers test samples have been performed at the Imaging and Materials Science & Engineering (IMAT) beamline operating at the ISIS spallation neutron source (U.K.). The aim of these experiments was the full characterization of the chip misalignment and of the gaps between each pad in the quad Timepix sensor. Such misalignment causes distortions of the recorded shape of the sample analyzed. We present in this work a post-processing image procedure that considers and corrects these effects. Results of the correction will be discussed and the efficacy of this method evaluated.

  6. Alignment of large image series using cubic B-splines tessellation: application to transmission electron microscopy data.

    Science.gov (United States)

    Dauguet, Julien; Bock, Davi; Reid, R Clay; Warfield, Simon K

    2007-01-01

    3D reconstruction from serial 2D microscopy images depends on non-linear alignment of serial sections. For some structures, such as the neuronal circuitry of the brain, very large images at very high resolution are necessary to permit reconstruction. These very large images prevent the direct use of classical registration methods. We propose in this work a method to deal with the non-linear alignment of arbitrarily large 2D images using the finite support properties of cubic B-splines. After initial affine alignment, each large image is split into a grid of smaller overlapping sub-images, which are individually registered using cubic B-splines transformations. Inside the overlapping regions between neighboring sub-images, the coefficients of the knots controlling the B-splines deformations are blended, to create a virtual large grid of knots for the whole image. The sub-images are resampled individually, using the new coefficients, and assembled together into a final large aligned image. We evaluated the method on a series of large transmission electron microscopy images and our results indicate significant improvements compared to both manual and affine alignment.

  7. Untangling the contributions of image charge and laser profile for optimal photoemission of high-brightness electron beams

    International Nuclear Information System (INIS)

    Portman, J.; Zhang, H.; Makino, K.; Ruan, C. Y.; Berz, M.; Duxbury, P. M.

    2014-01-01

    Using our model for the simulation of photoemission of high brightness electron beams, we investigate the virtual cathode physics and the limits to spatio-temporal and spectroscopic resolution originating from the image charge on the surface and from the profile of the exciting laser pulse. By contrasting the effect of varying surface properties (leading to expanding or pinned image charge), laser profiles (Gaussian, uniform, and elliptical), and aspect ratios (pancake- and cigar-like) under different extraction field strengths and numbers of generated electrons, we quantify the effect of these experimental parameters on macroscopic pulse properties such as emittance, brightness (4D and 6D), coherence length, and energy spread. Based on our results, we outline optimal conditions of pulse generation for ultrafast electron microscope systems that take into account constraints on the number of generated electrons and on the required time resolution.

  8. Expression of the Transcription Factor E4BP4 in Human Basophils

    DEFF Research Database (Denmark)

    Jensen, Bettina Margrethe; Gohr, Maria; Poulsen, Lars Kærgaard

    2014-01-01

    Rationale The cytokine IL-3 plays an important role for human basophil development, function and survival. IL-3 is also reported to induce the expression of the transcription factor E4BP4, but it is not known whether E4BP4 is expressed in basophils and influences basophil responsiveness. The aim...... by Alcian blue. RNA was extracted (0.005-0.02 µg RNA from 0.5 - 1 x 106 cells), and the corresponding cDNA analyzed by real-time PCR where E4BP4 expression was calculated as 2-(CT(E4BP4) - CT(β-actin)). E4BP4 protein expression was visualized in basophil lysates (107 cells/ml) by Western blot followed...... the transcription factor E4BP4 which might have an impact on basophil histamine release....

  9. An electronic image processing device featuring continuously selectable two-dimensional bipolar filter functions and real-time operation

    International Nuclear Information System (INIS)

    Charleston, B.D.; Beckman, F.H.; Franco, M.J.; Charleston, D.B.

    1981-01-01

    A versatile electronic-analogue image processing system has been developed for use in improving the quality of various types of images with emphasis on those encountered in experimental and diagnostic medicine. The operational principle utilizes spatial filtering which selectively controls the contrast of an image according to the spatial frequency content of relevant and non-relevant features of the image. Noise can be reduced or eliminated by selectively lowering the contrast of information in the high spatial frequency range. Edge sharpness can be enhanced by accentuating the upper midrange spatial frequencies. Both methods of spatial frequency control may be adjusted continuously in the same image to obtain maximum visibility of the features of interest. A precision video camera is used to view medical diagnostic images, either prints, transparencies or CRT displays. The output of the camera provides the analogue input signal for both the electronic processing system and the video display of the unprocessed image. The video signal input to the electronic processing system is processed by a two-dimensional spatial convolution operation. The system employs charged-coupled devices (CCDs), both tapped analogue delay lines (TADs) and serial analogue delay lines (SADs), to store information in the form of analogue potentials which are constantly being updated as new sampled analogue data arrive at the input. This information is convolved with a programmed bipolar radially symmetrical hexagonal function which may be controlled and varied at each radius by the operator in real-time by adjusting a set of front panel controls or by a programmed microprocessor control. Two TV monitors are used, one for processed image display and the other for constant reference to the original image. The working prototype has a full-screen display matrix size of 200 picture elements per horizontal line by 240 lines. The matrix can be expanded vertically and horizontally for the

  10. Transmission dosimetry with a liquid-filled electronic portal imaging device

    International Nuclear Information System (INIS)

    Boellaard, R.; Van Herk, M.; Mijnheer, B.J.

    1995-01-01

    The aim of transmission dosimetry is to correlate transmission dose values with patient dose values. A liquid-filled electronic portal imaging device (EPID) has been developed. After determination of the dose response relationship, i.e. the relation between pixel value and dose rate, for clinical situations it was found that the EPID is applicable for two-dimensional dosimetry with an accuracy of about 1%. The aim of this study was to investigate transmission dose distributions at different phantom-detector distances to predict exit dose distributions from transmission dose images. An extensive set of transmission dose measurements below homogeneous phantoms were performed with the EPID. The influence of several parameters such as field size, phantom thickness, phantom-detector distance and phantom-source distance on the transmission dose and its distribution were investigated. The two-dimensional transmission dose images were separated into two components: a primary dose and a scattered dose distribution. It was found that the scattered dose is maximal at a phantom thickness of about 10 cm. The scattered dose distribution below a homogeneous phantom has a Gaussian shape. The width of the Gaussian is small at small phantom-detector distances and increases for larger phantom-detector distances. The dependence of the scattered dose distribution on the field size at various phantom-detector distances has been used to estimate the dose distribution at the exit site of the phantom. More work is underway to determine the exit dose distributions for clinical situations, including the presence of inhomogeneities

  11. Digital electronics for 256 anode Hamamatsu H9500 PSPMT arrays in full-volume Compton imagers

    International Nuclear Information System (INIS)

    Harris, J T; Grudberg, P M; Warburton, W K

    2014-01-01

    Ziock et al.'s [1] recent Monte Carlo study of a proposed ''full-volume'' Compton Imaging Camera concluded that simultaneously locating a Compton scatter event's multiple interaction points within a single large scintillator crystal might be possible at 1 mm spatial resolution using a coded aperture mask sandwiched between two light guides and coupled to a position sensitive photomultiplier (PSPMT) to record the output light pattern. The method promises high efficiency at a relatively low cost. They are currently developing a lower resolution prototype using a large cubic scintillator (25.4 cm/side) whose masked face will be tiled with 25 Hamamatsu H9500 PSPMTs (6,400 outputs). XIA has contracted to develop and produce the readout electronics, which present several significant design challenges, including capturing all 6,400 anode outputs individually, with single photon sensitivity, in a compact format that will fit behind the tiled PSPMTs. 10,000 event/sec operation is desired, as is a cost of less than about $50/channel. In our approach, each PSPMT front end integrates the 256 anode signals and 8-1 multiplexes them to 32 differential outputs that are digitized in a PXI card using 4 octal 50 MHz ADCs. The multiplexers run at 8 MHz, sampling each anode at 1 MHz, which becomes the image frame rate. The ADC signals are demultiplexed and digitally filtered to extract the number of photons in each pixel in the full 2-D image. The design has been completed and built and is undergoing evaluation tests at the single PSPMT level

  12. Transmission dosimetry with a liquid-filled electronic portal imaging device

    Energy Technology Data Exchange (ETDEWEB)

    Boellaard, R; Van Herk, M; Mijnheer, B J [Nederlands Kanker Inst. ` Antoni van Leeuwenhoekhuis` , Amsterdam (Netherlands)

    1995-12-01

    The aim of transmission dosimetry is to correlate transmission dose values with patient dose values. A liquid-filled electronic portal imaging device (EPID) has been developed. After determination of the dose response relationship, i.e. the relation between pixel value and dose rate, for clinical situations it was found that the EPID is applicable for two-dimensional dosimetry with an accuracy of about 1%. The aim of this study was to investigate transmission dose distributions at different phantom-detector distances to predict exit dose distributions from transmission dose images. An extensive set of transmission dose measurements below homogeneous phantoms were performed with the EPID. The influence of several parameters such as field size, phantom thickness, phantom-detector distance and phantom-source distance on the transmission dose and its distribution were investigated. The two-dimensional transmission dose images were separated into two components: a primary dose and a scattered dose distribution. It was found that the scattered dose is maximal at a phantom thickness of about 10 cm. The scattered dose distribution below a homogeneous phantom has a Gaussian shape. The width of the Gaussian is small at small phantom-detector distances and increases for larger phantom-detector distances. The dependence of the scattered dose distribution on the field size at various phantom-detector distances has been used to estimate the dose distribution at the exit site of the phantom. More work is underway to determine the exit dose distributions for clinical situations, including the presence of inhomogeneities.

  13. Multi-color imaging of fluorescent nanodiamonds in living HeLa cells using direct electron-beam excitation.

    Science.gov (United States)

    Nawa, Yasunori; Inami, Wataru; Lin, Sheng; Kawata, Yoshimasa; Terakawa, Susumu; Fang, Chia-Yi; Chang, Huan-Cheng

    2014-03-17

    Multi-color, high spatial resolution imaging of fluorescent nanodiamonds (FNDs) in living HeLa cells has been performed with a direct electron-beam excitation-assisted fluorescence (D-EXA) microscope. In this technique, fluorescent materials are directly excited with a focused electron beam and the resulting cathodoluminescence (CL) is detected with nanoscale resolution. Green- and red-light-emitting FNDs were employed for two-color imaging, which were observed simultaneously in the cells with high spatial resolution. This technique could be applied generally for multi-color immunostaining to reveal various cell functions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. High-efficiency detector of secondary and backscattered electrons for low-dose imaging in the ESEM

    Czech Academy of Sciences Publication Activity Database

    Neděla, Vilém; Tihlaříková, Eva; Runštuk, Jiří; Hudec, Jiří

    2018-01-01

    Roč. 184 (2018), s. 1-11 ISSN 0304-3991 R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : detectors * scintillators * low-dose imaging * energy filtration * MC simulations Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Electrical and electronic engineering Impact factor: 2.843, year: 2016

  15. Scanning electron-acoustic imaging of residual stress distributions in aluminum metal and ZrSiO4 multiphase ceramics

    International Nuclear Information System (INIS)

    Zhang, B.Y.; Jiang, F.M.; Shi, Y.; Yin, Q.R.; Qian, M.L.

    1997-01-01

    The scanning electron-acoustic imaging technique has been used in the characterization of the residual stress field distributions existing in the subsurface in aluminum disks and 20 vol% SiC ( w)/ZrSiO 4 multiphase ceramics left by Vicker close-quote s indentation. The experimental results reveal that the distribution areas are the plastic-elastic interchange zones. The electron-acoustic signal generation mechanism in the samples are discussed. copyright 1997 American Institute of Physics

  16. Instruments for radiation measurement in biosciences. Series 3. radioluminography. 11. Application of imaging plate in transmission electron microscopy

    International Nuclear Information System (INIS)

    Oikawa, Tetsuo

    1999-01-01

    Properties and application of the imaging plate (IP) in transmission electron microscopy (TEM) are reviewed. TEM has the resolution level of around 0.2 nm, which enables direct observation of molecules and atoms. In TEM, there are such recording systems as photographic film, TV camera, slow-scan CCD camera and IP. IP, to the electron beam, has the higher sensitivity than the film and has the broad dynamic range. Linearity between the input beam intensity and output signal is good, which makes it possible to record the image even with the small electron dose. Signal/noise ratio and detective quantum efficiency are important factors for precise image analysis. Fading phenomenon is a defect of IP, which weakens the signal output as time passing. For instance of application, IP is used for imaging of AgBr crystal fragile to strong electron beam required for the film. IP is necessary for quantitative analysis of TEM images and for the recently developed energy-filter TEM. (K.H.)

  17. In situ Charge Density Imaging of Metamaterials made with Switchable Two dimensionalElectron Gas at Oxide Heterointerfaces

    Science.gov (United States)

    2017-11-28

    engineering of complex oxide systems. This work has been accepted for publication in Nature Nanotechnology (“Direct Imaging of the Electron Liquid at Oxide...mail address: eom@engr.wisc.edu - Institution: University of Wisconsin-Madison - Mailing Address: 2166 ECB, 1550 Engineering Drive, Madison, WI 53706...Interfaces” K. Song et al., in press, Nature Nanotechnology (2018)) Figure 1. Direct imaging of the 2DELs at oxide interfaces. a, b, 2-D surface

  18. E4orf1 Enhances Glucose Uptake Independent of Proximal Insulin Signaling.

    Science.gov (United States)

    Na, Ha-Na; Hegde, Vijay; Dubuisson, Olga; Dhurandhar, Nikhil V

    2016-01-01

    Impaired proximal insulin signaling is often present in diabetes. Hence, approaches to enhance glucose disposal independent of proximal insulin signaling are desirable. Evidence indicates that Adenovirus-derived E4orf1 protein may offer such an approach. This study determined if E4orf1 improves insulin sensitivity and downregulates proximal insulin signaling in vivo and enhances cellular glucose uptake independent of proximal insulin signaling in vitro. High fat fed mice were injected with a retrovirus plasmid expressing E4orf1, or a null vector. E4orf1 significantly improved insulin sensitivity in response to a glucose load. Yet, their proximal insulin signaling in fat depots was impaired, as indicated by reduced tyrosine phosphorylation of insulin receptor (IR), and significantly increased abundance of ectonucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1). In 3T3-L1 pre-adipocytes E4orf1 expression impaired proximal insulin signaling. Whereas, treatment with rosiglitazone reduced ENPP1 abundance. Unaffected by IR-KD (insulin receptor knockdown) with siRNA, E4orf1 significantly up-regulated distal insulin signaling pathway and enhanced cellular glucose uptake. In vivo, E4orf1 impairs proximal insulin signaling in fat depots yet improves glycemic control. This is probably explained by the ability of E4orf1 to promote cellular glucose uptake independent of proximal insulin signaling. E4orf1 may provide a therapeutic template to enhance glucose disposal in the presence of impaired proximal insulin signaling.

  19. E4orf1 Enhances Glucose Uptake Independent of Proximal Insulin Signaling.

    Directory of Open Access Journals (Sweden)

    Ha-Na Na

    Full Text Available Impaired proximal insulin signaling is often present in diabetes. Hence, approaches to enhance glucose disposal independent of proximal insulin signaling are desirable. Evidence indicates that Adenovirus-derived E4orf1 protein may offer such an approach. This study determined if E4orf1 improves insulin sensitivity and downregulates proximal insulin signaling in vivo and enhances cellular glucose uptake independent of proximal insulin signaling in vitro. High fat fed mice were injected with a retrovirus plasmid expressing E4orf1, or a null vector. E4orf1 significantly improved insulin sensitivity in response to a glucose load. Yet, their proximal insulin signaling in fat depots was impaired, as indicated by reduced tyrosine phosphorylation of insulin receptor (IR, and significantly increased abundance of ectonucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1. In 3T3-L1 pre-adipocytes E4orf1 expression impaired proximal insulin signaling. Whereas, treatment with rosiglitazone reduced ENPP1 abundance. Unaffected by IR-KD (insulin receptor knockdown with siRNA, E4orf1 significantly up-regulated distal insulin signaling pathway and enhanced cellular glucose uptake. In vivo, E4orf1 impairs proximal insulin signaling in fat depots yet improves glycemic control. This is probably explained by the ability of E4orf1 to promote cellular glucose uptake independent of proximal insulin signaling. E4orf1 may provide a therapeutic template to enhance glucose disposal in the presence of impaired proximal insulin signaling.

  20. Automated analysis of heterogeneous carbon nanostructures by high-resolution electron microscopy and on-line image processing

    International Nuclear Information System (INIS)

    Toth, P.; Farrer, J.K.; Palotas, A.B.; Lighty, J.S.; Eddings, E.G.

    2013-01-01

    High-resolution electron microscopy is an efficient tool for characterizing heterogeneous nanostructures; however, currently the analysis is a laborious and time-consuming manual process. In order to be able to accurately and robustly quantify heterostructures, one must obtain a statistically high number of micrographs showing images of the appropriate sub-structures. The second step of analysis is usually the application of digital image processing techniques in order to extract meaningful structural descriptors from the acquired images. In this paper it will be shown that by applying on-line image processing and basic machine vision algorithms, it is possible to fully automate the image acquisition step; therefore, the number of acquired images in a given time can be increased drastically without the need for additional human labor. The proposed automation technique works by computing fields of structural descriptors in situ and thus outputs sets of the desired structural descriptors in real-time. The merits of the method are demonstrated by using combustion-generated black carbon samples. - Highlights: ► The HRTEM analysis of heterogeneous nanostructures is a tedious manual process. ► Automatic HRTEM image acquisition and analysis can improve data quantity and quality. ► We propose a method based on on-line image analysis for the automation of HRTEM image acquisition. ► The proposed method is demonstrated using HRTEM images of soot particles

  1. X-ray Microscopy as an Approach to Increasing Accuracy and Efficiency of Serial Block-face Imaging for Correlated Light and Electron Microscopy of Biological Specimens

    OpenAIRE

    Bushong, Eric A.; Johnson, Donald D.; Kim, Keun-Young; Terada, Masako; Hatori, Megumi; Peltier, Steven T.; Panda, Satchidananda; Merkle, Arno; Ellisman, Mark H.

    2014-01-01

    The recently developed three-dimensional electron microscopic (EM) method of serial block-face scanning electron microscopy (SBEM) has rapidly established itself as a powerful imaging approach. Volume EM imaging with this scanning electron microscopy (SEM) method requires intense staining of biological specimens with heavy metals to allow sufficient back-scatter electron signal and also to render specimens sufficiently conductive to control charging artifacts. These more extreme heavy metal s...

  2. Quantitative analysis of the myelin g-ratio from electron microscopy images of the macaque corpus callosum

    Directory of Open Access Journals (Sweden)

    Nikola Stikov

    2015-09-01

    Full Text Available We provide a detailed morphometric analysis of eight transmission electron micrographs (TEMs obtained from the corpus callosum of one cynomolgus macaque. The raw TEM images are included in the article, along with the distributions of the axon caliber and the myelin g-ratio in each image. The distributions are analyzed to determine the relationship between axon caliber and g-ratio, and compared against the aggregate metrics (myelin volume fraction, fiber volume fraction, and the aggregate g-ratio, as defined in the accompanying research article entitled ‘In vivo histology of the myelin g-ratio with magnetic resonance imaging’ (Stikov et al., NeuroImage, 2015.

  3. Imaging with a 90 frames/s microbolometer focal plane array and high-power terahertz free electron laser

    International Nuclear Information System (INIS)

    Dem'yanenko, M. A.; Esaev, D. G.; Knyazev, B. A.; Vinokurov, N. A.; Kulipanov, G. N.

    2008-01-01

    An uncooled microbolometer focal plane array (FPA) has been developed and used for imaging of objects illuminated by monochromatic coherent radiation of a free electron laser tunable in the range of 1.25-2.5 THz. A sensitivity threshold of 1.3x10 -3 W/cm 2 was obtained for the FPA with a homemade absolute interferometric power meter. Videos up to 90 frames/s were recorded in both transmission and reflection/scattering modes. When objects were illuminated by laser radiation scattered by a rough metal surface, speckled images were observed. Good quality terahertz images were achieved through the fast rotation of the scatterer

  4. Atomic imaging by x-ray-fluorescence holography and electron-emission holography: A comparative theoretical study

    International Nuclear Information System (INIS)

    Len, P.M.; Thevuthasan, S.; Fadley, C.S.; Kaduwela, A.P.; Van Hove, M.A.

    1994-01-01

    We consider from a theoretical viewpoint the direct imaging of atoms at and near the surfaces of solids by both x-ray-fluorescence holography (XFH) and electron-emission holography (EEH). The more ideal nature of x-ray scattering makes XFH images superior to those in single-energy EEH. The overlap of real and twin features for pairs of atoms at ±a can cause their XFH or EEH atomic images to cancel for certain combinations of wave vector and |a|. The relative merits of XFH and EEH for structure studies are considered

  5. Robust Estimation of Electron Density From Anatomic Magnetic Resonance Imaging of the Brain Using a Unifying Multi-Atlas Approach

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Shangjie [Tianjin Key Laboratory of Process Measurement and Control, School of Electrical Engineering and Automation, Tianjin University, Tianjin (China); Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, California (United States); Hara, Wendy; Wang, Lei; Buyyounouski, Mark K.; Le, Quynh-Thu; Xing, Lei [Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, California (United States); Li, Ruijiang, E-mail: rli2@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, California (United States)

    2017-03-15

    Purpose: To develop a reliable method to estimate electron density based on anatomic magnetic resonance imaging (MRI) of the brain. Methods and Materials: We proposed a unifying multi-atlas approach for electron density estimation based on standard T1- and T2-weighted MRI. First, a composite atlas was constructed through a voxelwise matching process using multiple atlases, with the goal of mitigating effects of inherent anatomic variations between patients. Next we computed for each voxel 2 kinds of conditional probabilities: (1) electron density given its image intensity on T1- and T2-weighted MR images; and (2) electron density given its spatial location in a reference anatomy, obtained by deformable image registration. These were combined into a unifying posterior probability density function using the Bayesian formalism, which provided the optimal estimates for electron density. We evaluated the method on 10 patients using leave-one-patient-out cross-validation. Receiver operating characteristic analyses for detecting different tissue types were performed. Results: The proposed method significantly reduced the errors in electron density estimation, with a mean absolute Hounsfield unit error of 119, compared with 140 and 144 (P<.0001) using conventional T1-weighted intensity and geometry-based approaches, respectively. For detection of bony anatomy, the proposed method achieved an 89% area under the curve, 86% sensitivity, 88% specificity, and 90% accuracy, which improved upon intensity and geometry-based approaches (area under the curve: 79% and 80%, respectively). Conclusion: The proposed multi-atlas approach provides robust electron density estimation and bone detection based on anatomic MRI. If validated on a larger population, our work could enable the use of MRI as a primary modality for radiation treatment planning.

  6. Wavelength dependent photoelectron circular dichroism of limonene studied by femtosecond multiphoton laser ionization and electron-ion coincidence imaging

    Science.gov (United States)

    Rafiee Fanood, Mohammad M.; Janssen, Maurice H. M.; Powis, Ivan

    2016-09-01

    Enantiomers of the monoterpene limonene have been investigated by (2 + 1) resonance enhanced multiphoton ionization and photoelectron circular dichroism employing tuneable, circularly polarized femtosecond laser pulses. Electron imaging detection provides 3D momentum measurement while electron-ion coincidence detection can be used to mass-tag individual electrons. Additional filtering, by accepting only parent ion tagged electrons, can be then used to provide discrimination against higher energy dissociative ionization mechanisms where more than three photons are absorbed to better delineate the two photon resonant, one photon ionization pathway. The promotion of different vibrational levels and, tentatively, different electronic ion core configurations in the intermediate Rydberg states can be achieved with different laser excitation wavelengths (420 nm, 412 nm, and 392 nm), in turn producing different state distributions in the resulting cations. Strong chiral asymmetries in the lab frame photoelectron angular distributions are quantified, and a comparison made with a single photon (synchrotron radiation) measurement at an equivalent photon energy.

  7. Comparison of 250 MHz electron spin echo and continuous wave oxygen EPR imaging methods for in vivo applications

    Science.gov (United States)

    Epel, Boris; Sundramoorthy, Subramanian V.; Barth, Eugene D.; Mailer, Colin; Halpern, Howard J.

    2011-01-01

    Purpose: The authors compare two electron paramagnetic resonance imaging modalities at 250 MHz to determine advantages and disadvantages of those modalities for in vivo oxygen imaging. Methods: Electron spin echo (ESE) and continuous wave (CW) methodologies were used to obtain three-dimensional images of a narrow linewidth, water soluble, nontoxic oxygen-sensitive trityl molecule OX063 in vitro and in vivo. The authors also examined sequential images obtained from the same animal injected intravenously with trityl spin probe to determine temporal stability of methodologies. Results: A study of phantoms with different oxygen concentrations revealed a threefold advantage of the ESE methodology in terms of reduced imaging time and more precise oxygen resolution for samples with less than 70 torr oxygen partial pressure. Above∼100 torr, CW performed better. The images produced by both methodologies showed pO2 distributions with similar mean values. However, ESE images demonstrated superior performance in low pO2 regions while missing voxels in high pO2 regions. Conclusions: ESE and CW have different areas of applicability. ESE is superior for hypoxia studies in tumors. PMID:21626937

  8. Electronics

    Science.gov (United States)

    2001-01-01

    International Acer Incorporated, Hsin Chu, Taiwan Aerospace Industrial Development Corporation, Taichung, Taiwan American Institute of Taiwan, Taipei, Taiwan...Singapore and Malaysia .5 - 4 - The largest market for semiconductor products is the high technology consumer electronics industry that consumes up...Singapore, and Malaysia . A new semiconductor facility costs around $3 billion to build and takes about two years to become operational

  9. High-efficiency detector of secondary and backscattered electrons for low-dose imaging in the ESEM.

    Science.gov (United States)

    Neděla, Vilém; Tihlaříková, Eva; Runštuk, Jiří; Hudec, Jiří

    2018-01-01

    A new Combined System for high-efficiency detection of Secondary and Backscattered Electrons (CSSBE) in the ESEM consists of three detectors: an ionisation SE detector, an improved scintillation BSE detector, and a new Ionisation Secondary Electron Detector with an electrostatic Separator (ISEDS). The ISEDS optimizes conditions for electron-gas ionisation phenomena in the ESEM to achieve a strongly amplified signal from the secondary electrons with a minimal contribution from backscattered and beam electrons. For this purpose, it is originally equipped with an electrostatic separator, which focuses signal electrons towards a detection electrode and controls the concentration of positive ions above the sample. The working principle of the ISEDS is explained by simulations of signal electron trajectories in gas using the EOD program with our Monte Carlo module. The ability to detect the signal electrons in a selected range of energies is described with Geant4 Monte Carlo simulations of electron-solid interactions and proven by experimental results. High-efficiency detection of the ISEDS is demonstrated by imaging a low atomic number sample under a reduced beam energy of 5 keV, very low beam currents of up to 0.2 pA, and gas pressure of hundreds of Pa. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Backscattered electron SEM imaging of resin sections from plant specimens: observation of histological to subcellular structure and CLEM.

    Science.gov (United States)

    Rizzo, N W; Duncan, K E; Bourett, T M; Howard, R J

    2016-08-01

    We have refined methods for biological specimen preparation and low-voltage backscattered electron imaging in the scanning electron microscope that allow for observation at continuous magnifications of ca. 130-70 000 X, and documentation of tissue and subcellular ultrastructure detail. The technique, based upon early work by Ogura & Hasegawa (1980), affords use of significantly larger sections from fixed and resin-embedded specimens than is possible with transmission electron microscopy while providing similar data. After microtomy, the sections, typically ca. 750 nm thick, were dried onto the surface of glass or silicon wafer and stained with heavy metals-the use of grids avoided. The glass/wafer support was then mounted onto standard scanning electron microscopy sample stubs, carbon-coated and imaged directly at an accelerating voltage of 5 kV, using either a yttrium aluminum garnet or ExB backscattered electron detector. Alternatively, the sections could be viewed first by light microscopy, for example to document signal from a fluorescent protein, and then by scanning electron microscopy to provide correlative light/electron microscope (CLEM) data. These methods provide unobstructed access to ultrastructure in the spatial context of a section ca. 7 × 10 mm in size, significantly larger than the typical 0.2 × 0.3 mm section used for conventional transmission electron microscopy imaging. Application of this approach was especially useful when the biology of interest was rare or difficult to find, e.g. a particular cell type, developmental stage, large organ, the interface between cells of interacting organisms, when contextual information within a large tissue was obligatory, or combinations of these factors. In addition, the methods were easily adapted for immunolocalizations. © 2015 The Author. Journal of Microscopy published by John Wiley & Sons, Ltd on behalf of the Royal Microscopical Society.

  11. MATLAB Algorithms for Rapid Detection and Embedding of Palindrome and Emordnilap Electronic Watermarks in Simulated Chemical and Biological Image Data

    National Research Council Canada - National Science Library

    Robbins, Ronny C

    2004-01-01

    .... This is similar to words such as STOP which when flipped left right gives the new word POTS. Emordnilap is palindrome spelled backwards. This paper explores the use of MATLAB algorithms in the rapid detection and embedding of palindrome and emordnilap electronic watermarks in simulated chemical and biological Image Data.

  12. Spatial profiling of degradation processes in hindered-amine-stabilized polymers by electron spin resonance imaging of nitroxides

    Czech Academy of Sciences Publication Activity Database

    Marek, Antonín; Kaprálková, Ludmila; Pfleger, Jiří; Pospíšil, Jan; Pilař, Jan

    2005-01-01

    Roč. 99, S (2005), s. 195-198 ISSN 0009-2770. [Meeting on Chemistry and Life /3./. Brno, 20.9.2005-22.9.2005] Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer degradation * nitroxides * electron spin resonance imaging Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.445, year: 2005

  13. Electronic Document Imaging and Optical Storage Systems for Local Governments: An Introduction. Local Government Records Technical Information Series. Number 21.

    Science.gov (United States)

    Schwartz, Stanley F.

    This publication introduces electronic document imaging systems and provides guidance for local governments in New York in deciding whether such systems should be adopted for their own records and information management purposes. It advises local governments on how to develop plans for using such technology by discussing its advantages and…

  14. Overview of 3-year experience with large-scale electronic portal imaging device-based 3-dimensional transit dosimetry

    NARCIS (Netherlands)

    Mijnheer, Ben J.; González, Patrick; Olaciregui-Ruiz, Igor; Rozendaal, Roel A.; van Herk, Marcel; Mans, Anton

    2015-01-01

    To assess the usefulness of electronic portal imaging device (EPID)-based 3-dimensional (3D) transit dosimetry in a radiation therapy department by analyzing a large set of dose verification results. In our institution, routine in vivo dose verification of all treatments is performed by means of 3D

  15. 76 FR 54373 - Airworthiness Directives; Austro Engine GmbH Model E4 Diesel Piston Engines

    Science.gov (United States)

    2011-09-01

    ... diesel piston engines, with high-pressure (HP) fuel pump, part number (P/N) E4A- 30-100-000, installed... Airworthiness Directives; Austro Engine GmbH Model E4 Diesel Piston Engines AGENCY: Federal Aviation... pressure supply for excessive oscillations to determine if high-pressure (HP) fuel pumps have been exposed...

  16. Apolipoprotein E4 reduces evoked hippocampal acetylcholine release in adult mice

    Czech Academy of Sciences Publication Activity Database

    Dolejší, Eva; Liraz, O.; Rudajev, Vladimír; Zimčík, Pavel; Doležal, Vladimír; Michaelson, D. M.

    2016-01-01

    Roč. 136, č. 3 (2016), s. 503-509 ISSN 0022-3042 R&D Projects: GA MŠk(CZ) LH13269 Institutional support: RVO:67985823 Keywords : acetylcholine release * Alzheimer's disease (AD) * apolipoprotein E4 (apoE4) * hippocampus Subject RIV: FH - Neurology Impact factor: 4.083, year: 2016

  17. A 3D Image Filter for Parameter-Free Segmentation of Macromolecular Structures from Electron Tomograms

    Science.gov (United States)

    Ali, Rubbiya A.; Landsberg, Michael J.; Knauth, Emily; Morgan, Garry P.; Marsh, Brad J.; Hankamer, Ben

    2012-01-01

    3D image reconstruction of large cellular volumes by electron tomography (ET) at high (≤5 nm) resolution can now routinely resolve organellar and compartmental membrane structures, protein coats, cytoskeletal filaments, and macromolecules. However, current image analysis methods for identifying in situ macromolecular structures within the crowded 3D ultrastructural landscape of a cell remain labor-intensive, time-consuming, and prone to user-bias and/or error. This paper demonstrates the development and application of a parameter-free, 3D implementation of the bilateral edge-detection (BLE) algorithm for the rapid and accurate segmentation of cellular tomograms. The performance of the 3D BLE filter has been tested on a range of synthetic and real biological data sets and validated against current leading filters—the pseudo 3D recursive and Canny filters. The performance of the 3D BLE filter was found to be comparable to or better than that of both the 3D recursive and Canny filters while offering the significant advantage that it requires no parameter input or optimisation. Edge widths as little as 2 pixels are reproducibly detected with signal intensity and grey scale values as low as 0.72% above the mean of the background noise. The 3D BLE thus provides an efficient method for the automated segmentation of complex cellular structures across multiple scales for further downstream processing, such as cellular annotation and sub-tomogram averaging, and provides a valuable tool for the accurate and high-throughput identification and annotation of 3D structural complexity at the subcellular level, as well as for mapping the spatial and temporal rearrangement of macromolecular assemblies in situ within cellular tomograms. PMID:22479430

  18. Electronic portal image assisted reduction of systematic set-up errors in head and neck irradiation

    International Nuclear Information System (INIS)

    Boer, Hans C.J. de; Soernsen de Koste, John R. van; Creutzberg, Carien L.; Visser, Andries G.; Levendag, Peter C.; Heijmen, Ben J.M.

    2001-01-01

    Purpose: To quantify systematic and random patient set-up errors in head and neck irradiation and to investigate the impact of an off-line correction protocol on the systematic errors. Material and methods: Electronic portal images were obtained for 31 patients treated for primary supra-glottic larynx carcinoma who were immobilised using a polyvinyl chloride cast. The observed patient set-up errors were input to the shrinking action level (SAL) off-line decision protocol and appropriate set-up corrections were applied. To assess the impact of the protocol, the positioning accuracy without application of set-up corrections was reconstructed. Results: The set-up errors obtained without set-up corrections (1 standard deviation (SD)=1.5-2 mm for random and systematic errors) were comparable to those reported in other studies on similar fixation devices. On an average, six fractions per patient were imaged and the set-up of half the patients was changed due to the decision protocol. Most changes were detected during weekly check measurements, not during the first days of treatment. The application of the SAL protocol reduced the width of the distribution of systematic errors to 1 mm (1 SD), as expected from simulations. A retrospective analysis showed that this accuracy should be attainable with only two measurements per patient using a different off-line correction protocol, which does not apply action levels. Conclusions: Off-line verification protocols can be particularly effective in head and neck patients due to the smallness of the random set-up errors. The excellent set-up reproducibility that can be achieved with such protocols enables accurate dose delivery in conformal treatments

  19. Transabdominal ultrasonography, computed tomography and electronic portal imaging for 3-dimensional conformal radiotherapy for prostate cancer

    International Nuclear Information System (INIS)

    Jereczek-Fossa, B.A.; Orecchia, R.; Cattani, F.; Garibaldi, C.; Cambria, R.; Valenti, M.; Ciocca, M.; Zerini, D.; Boboc, G.I.; Vavassori, A.; Ivaldi, G.B.; Kowalczyk, A.; Matei, D.V.; Cobelli, O. de

    2007-01-01

    Purpose: To evaluate the feasibility and accuracy of daily B-mode acquisition and targeting ultrasound-based prostate localization (BAT trademark) and to compare it with computed tomography (CT) and electronic portal imaging (EPI) in 3-dimensional conformal radiotherapy (3-D CRT) for prostate cancer. Patients and Methods: Ten patients were treated with 3-D CRT (72 Gy/30 fractions, 2.4 Gy/fraction, equivalent to 80 Gy/40 fractions, for α/β ratio of 1.5 Gy) and daily BAT-based prostate localization. For the first 5 fractions, CT and EPI were also performed in order to compare organ-motion and set-up error, respectively. Results: 287 BAT-, 50 CT- and 46 EPI-alignments were performed. The average BAT-determined misalignments in latero-lateral, antero-posterior and cranio-caudal directions were -0.9 mm ± 3.3 mm, 1.0 mm ± 4.0 mm and -0.9 mm ± 3.8 mm, respectively. The differences between BAT- and CT-determined organ-motion in latero-lateral, antero-posterior and cranio-caudal directions were 2.7 mm ± 1.9 mm, 3.9 ± 2.8 mm and 3.4 ± 3.0 mm, respectively. Weak correlation was found between BAT- and CT-determined misalignments in antero-posterior direction, while no correlation was observed in latero-lateral and cranio-caudal directions. The correlation was more significant when only data of good image-quality patients were analyzed (8 patients). Conclusion: BAT ensures the relative positions of target are the same during treatment and in treatment plan, however, the reliability of alignment is patient-dependent. The average BAT-determined misalignments were small, confirming the prevalence of random errors in 3-D CRT. Further study is warranted in order to establish the clinical value of BAT. (orig.)

  20. Towards the development of a comprehensive model of an electronic portal imaging device using Geant4

    International Nuclear Information System (INIS)

    Blake, S.; Kuncic, Z.; Vial, P.; Holloway, L.

    2010-01-01

    Full text: This work represents the first stage of an ongoing study to investigate the physical processes occurring within electronic portal imaging devices (EPlDs), including the effects of optical scattering on image quality and dosimetry. The objective of this work was to develop an initial Monte Carlo model of a linear accelerator (Iinac) beam and an EPID. The ability to simulate the radiation transport of both high energy and optical photons in a single Monte Carlo model was tested. Data from the Phase-space database for external beam radiotherapy (International Atomic Energy Agency, IAEA) was used with the Geant4 toolkit to construct a model of a Siemens Primus linac 6 MY photon source. Dose profiles and percent depth dose (PDD) curves were extracted from simulations of dose in water and compared to experimental measurements. A preliminary EPID model was developed to incorporate both high energy radiation and optical photon transport. Agreement in dose profiles inside the open beam was within 1.6%. Mean agreement in PDD curves beyond depth of dose maximum was within 6.1 % (local percent difference). The radiation transport of both high energy and optical photons were simulated and visualized in the EPID model. Further work is required to experimentally validate the EPID model. The comparison of simulated dose in water with measurements indicates that the IAEA phase-space may represent an accurate model of a linac source. We have demonstrated the feasibility of developing a comprehensive EPID model incorporating both high energy and optical physics in Geant4. (author)

  1. The use of an electronic portal imaging device for exit dosimetry and quality control measurements

    International Nuclear Information System (INIS)

    Kirby, Michael C.; Williams, Peter C.

    1995-01-01

    Purpose: To determine ways in which electronic portal imaging devices (EPIDs) could be used to (a) measure exit doses for external beam radiotherapy and (b) perform quality control checks on linear accelerators. Methods and Materials: When imaging, our fluoroscopic EPID adjusts the gain, offset, and frame acquisition time of the charge coupled device (CCD) camera automatically, to allow for the range of photon transmissions through the patient, and to optimize the signal-to-noise ratio. However, our EPID can be programmed to act as an integrating dosemeter. EPID dosemeter measurements were made for 20 MV photons, for different field sizes and thicknesses of unit density phantom material placed at varying exit surface to detector distances. These were compared with simultaneous Silicon diode exit dose measurements. Our exit dosimetry technique was verified using an anthropomorphic type phantom, and some initial measurements have been made for patients treated with irregularly shaped 20 MV x-ray fields. In this dosimetry mode, our EPID was also used to measure certain quality control parameters, x-ray field flatness, and the verification of segmented intensity modulated field prescriptions. Results: Configured for dosimetry, our EPID exhibited a highly linear response, capable of resolving individual monitor units. Exit doses could be measured to within about 3% of that measured using Silicon diodes. Field flatness was determined to within 1.5% of Farmer dosemeter measurements. Segmented intensity modulated fields can be easily verified. Conclusions: Our EPID has the versatility to assess a range of parameters pertinent to the delivery of high quality, high precision radiotherapy. When configured appropriately, it can measure exit doses in vivo, with reasonable accuracy, perform certain quick quality control checks, and analyze segmented intensity modulated treatment fields

  2. A combined positron emission tomography (PET)- electron paramagnetic resonance imaging (EPRI) system: initial evaluation of a prototype scanner.

    Science.gov (United States)

    Tseytlin, Mark; Stolin, Alexander V; Guggilapu, Priyaankadevi; Bobko, Andrey A; Khramtsov, Valery V; Tseytlin, Oxana; Raylman, Raymond R

    2018-04-20

    The advent of hybrid scanners, combining complementary modalities, has revolutionized imaging; enhancing clinical practice and biomedical research. In this project, we investigated the melding of two complementary, functional imaging methods: positron emission tomography (PET) and electron paramagnetic resonance imaging (EPRI). The PET radiotracers can provide important information about cellular parameters, such as glucose metabolism. While EPR probes can provide assessment of tissue microenvironment, measuring parameters such as oxygenation and pH, for example. A combined PET/EPRI scanner has the promise to provide new insights not attainable with current imagers by simultaneous acquisition of multiple components of tissue microenvironments. In this investigation, a prototype system was created by combing two existing scanners, modified for simultaneous imaging. Specifically, a silicon photomultiplier (SiPM) based PET scanner ring designed as a portable scanner was combined with an EPRI scanner designed for the imaging of small animals. The ability of the system to obtain simultaneous images was assessed with a small phantom consisting of four cylinders containing both PET and EPR tracers. The resulting images demonstrated the ability to obtain contemporaneous PET and ERP images without cross-modality interference. The next step in this project is the construction of pre-clinical PET/EPRI scanner for multi-parametric assessment of physiologically important parameters of tissue microenvironments. . © 2018 Institute of Physics and Engineering in Medicine.

  3. A combined positron emission tomography (PET)-electron paramagnetic resonance imaging (EPRI) system: initial evaluation of a prototype scanner

    Science.gov (United States)

    Tseytlin, Mark; Stolin, Alexander V.; Guggilapu, Priyaankadevi; Bobko, Andrey A.; Khramtsov, Valery V.; Tseytlin, Oxana; Raylman, Raymond R.

    2018-05-01

    The advent of hybrid scanners, combining complementary modalities, has revolutionized the application of advanced imaging technology to clinical practice and biomedical research. In this project, we investigated the melding of two complementary, functional imaging methods: positron emission tomography (PET) and electron paramagnetic resonance imaging (EPRI). PET radiotracers can provide important information about cellular parameters, such as glucose metabolism. While EPR probes can provide assessment of tissue microenvironment, measuring oxygenation and pH, for example. Therefore, a combined PET/EPRI scanner promises to provide new insights not attainable with current imagers by simultaneous acquisition of multiple components of tissue microenvironments. To explore the simultaneous acquisition of PET and EPR images, a prototype system was created by combining two existing scanners. Specifically, a silicon photomultiplier (SiPM)-based PET scanner ring designed as a portable scanner was combined with an EPRI scanner designed for the imaging of small animals. The ability of the system to obtain simultaneous images was assessed with a small phantom consisting of four cylinders containing both a PET tracer and EPR spin probe. The resulting images demonstrated the ability to obtain contemporaneous PET and EPR images without cross-modality interference. Given the promising results from this initial investigation, the next step in this project is the construction of the next generation pre-clinical PET/EPRI scanner for multi-parametric assessment of physiologically-important parameters of tissue microenvironments.

  4. Analysis of electron beam damage of exfoliated MoS2 sheets and quantitative HAADF-STEM imaging

    International Nuclear Information System (INIS)

    Garcia, Alejandra; Raya, Andres M.; Mariscal, Marcelo M.; Esparza, Rodrigo; Herrera, Miriam; Molina, Sergio I.; Scavello, Giovanni; Galindo, Pedro L.; Jose-Yacaman, Miguel; Ponce, Arturo

    2014-01-01

    In this work we examined MoS 2 sheets by aberration-corrected scanning transmission electron microscopy (STEM) at three different energies: 80, 120 and 200 kV. Structural damage of the MoS 2 sheets has been controlled at 80 kV according a theoretical calculation based on the inelastic scattering of the electrons involved in the interaction electron–matter. The threshold energy for the MoS 2 material has been found and experimentally verified in the microscope. At energies higher than the energy threshold we show surface and edge defects produced by the electron beam irradiation. Quantitative analysis at atomic level in the images obtained at 80 kV has been performed using the experimental images and via STEM simulations using SICSTEM software to determine the exact number of MoS 2 layers. - Highlights: • MoS 2 sheets were exfoliated by using hydrogen gas flow to separate the MoS 2 layers. • The optimum energy to avoid structural damage was calculated. • Cs-corrected STEM imaging was used to obtain atomic resolution images. • Three energies were used in STEM imaging: 80, 120 and 200 kV. • A quantitative method for determining the number of layers has been applied

  5. Time resolved, 2-D hard X-ray imaging of relativistic electron-beam target interactions on ETA-II

    International Nuclear Information System (INIS)

    Crist, C.E.; Sampayan, S.; Westenskow, G.; Caporaso, G.; Houck, T.; Weir, J.; Trimble, D.; Krogh, M.

    1998-01-01

    Advanced radiographic applications require a constant source size less than 1 mm. To study the time history of a relativistic electron beam as it interacts with a bremsstrahlung converter, one of the diagnostics they use is a multi-frame time-resolved hard x-ray camera. They are performing experiments on the ETA-II accelerator at Lawrence Livermore National Laboratory to investigate details of the electron beam/converter interactions. The camera they are using contains 6 time-resolved images, each image is a 5 ns frame. By starting each successive frame 10 ns after the previous frame, they create a 6-frame movie from the hard x-rays produced from the interaction of the 50-ns electron beam pulse

  6. Imaging and elemental mapping of biological specimens with a dual-EDS dedicated scanning transmission electron microscope

    Science.gov (United States)

    Wu, J.S.; Kim, A. M.; Bleher, R.; Myers, B.D.; Marvin, R. G.; Inada, H.; Nakamura, K.; Zhang, X.F.; Roth, E.; Li, S.Y.; Woodruff, T. K.; O'Halloran, T. V.; Dravid, Vinayak P.

    2013-01-01

    A dedicated analytical scanning transmission electron microscope (STEM) with dual energy dispersive spectroscopy (EDS) detectors has been designed for complementary high performance imaging as well as high sensitivity elemental analysis and mapping of biological structures. The performance of this new design, based on a Hitachi HD-2300A model, was evaluated using a variety of biological specimens. With three imaging detectors, both the surface and internal structure of cells can be examined simultaneously. The whole-cell elemental mapping, especially of heavier metal species that have low cross-section for electron energy loss spectroscopy (EELS), can be faithfully obtained. Optimization of STEM imaging conditions is applied to thick sections as well as thin sections of biological cells under low-dose conditions at room- and cryogenic temperatures. Such multimodal capabilities applied to soft/biological structures usher a new era for analytical studies in biological systems. PMID:23500508

  7. Diffraction-unlimited optical imaging of unstained living cells in liquid by electron beam scanning of luminescent environmental cells.

    Science.gov (United States)

    Miyazaki, Hideki T; Kasaya, Takeshi; Takemura, Taro; Hanagata, Nobutaka; Yasuda, Takeshi; Miyazaki, Hiroshi

    2013-11-18

    An environmental cell with a 50-nm-thick cathodoluminescent window was attached to a scanning electron microscope, and diffraction-unlimited near-field optical imaging of unstained living human lung epithelial cells in liquid was demonstrated. Electrons with energies as low as 0.8 - 1.2 kV are sufficiently blocked by the window without damaging the specimens, and form a sub-wavelength-sized illumination light source. A super-resolved optical image of the specimen adhered to the opposite window surface was acquired by a photomultiplier tube placed below. The cells after the observation were proved to stay alive. The image was formed by enhanced dipole radiation or energy transfer, and features as small as 62 nm were resolved.

  8. Apolipoprotein E4 causes early olfactory network abnormalities and short-term olfactory memory impairments.

    Science.gov (United States)

    Peng, Katherine Y; Mathews, Paul M; Levy, Efrat; Wilson, Donald A

    2017-02-20

    While apolipoprotein (Apo) E4 is linked to increased incidence of Alzheimer's disease (AD), there is growing evidence that it plays a role in functional brain irregularities that are independent of AD pathology. However, ApoE4-driven functional differences within olfactory processing regions have yet to be examined. Utilizing knock-in mice humanized to ApoE4 versus the more common ApoE3, we examined a simple olfactory perceptual memory that relies on the transfer of information from the olfactory bulb (OB) to the piriform cortex (PCX), the primary cortical region involved in higher order olfaction. In addition, we have recorded in vivo resting and odor-evoked local field potentials (LPF) from both brain regions and measured corresponding odor response magnitudes in anesthetized young (6-month-old) and middle-aged (12-month-old) ApoE mice. Young ApoE4 compared to ApoE3 mice exhibited a behavioral olfactory deficit coinciding with hyperactive odor-evoked response magnitudes within the OB that were not observed in older ApoE4 mice. Meanwhile, middle-aged ApoE4 compared to ApoE3 mice exhibited heightened response magnitudes in the PCX without a corresponding olfactory deficit, suggesting a shift with aging in ApoE4-driven effects from OB to PCX. Interestingly, the increased ApoE4-specific response in the PCX at middle-age was primarily due to a dampening of baseline spontaneous activity rather than an increase in evoked response power. Our findings indicate that early ApoE4-driven olfactory memory impairments and OB network abnormalities may be a precursor to later network dysfunction in the PCX, a region that not only is targeted early in AD, but may be selectively vulnerable to ApoE4 genotype. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  9. Evaluation of respiratory movement during gated radiotherapy using film and electronic portal imaging

    International Nuclear Information System (INIS)

    Ford, E.C.; Mageras, G.S.; Yorke, E.; Rosenzweig, K.E.; Wagman, R.; Ling, C.C.

    2002-01-01

    Purpose: To evaluate the effectiveness of a commercial system in reducing respiration-induced treatment uncertainty by gating the radiation delivery. Methods and Materials: The gating system considered here measures respiration from the position of a reflective marker on the patient's chest. Respiration-triggered planning CT scans were obtained for 8 patients (4 lung, 4 liver) at the intended phase of respiration (6 at end expiration and 2 at end inspiration). In addition, fluoroscopic movies were recorded simultaneously with the respiratory waveform. During the treatment sessions, gated localization films were used to measure the position of the diaphragm relative to the vertebral bodies, which was compared to the reference digitally reconstructed radiograph derived from the respiration-triggered planning CT. Variability was quantified by the standard deviation about the mean position. We also assessed the interfraction variability of soft tissue structures during gated treatment in 2 patients using an amorphous silicon electronic portal imaging device. Results: The gated localization films revealed an interfraction patient-averaged diaphragm variability of 2.8±1.0 mm (error bars indicate standard deviation in the patient population). The fluoroscopic data yielded a patient-averaged intrafraction diaphragm variability of 2.6±1.7 mm. With no gating, this intrafraction excursion became 6.9±2.1 mm. In gated localization films, the patient-averaged mean displacement of the diaphragm from the planning position was 0.0±3.9 mm. However, in 4 of the 8 patients, the mean (over localization films) displacement was >4 mm, indicating a systematic displacement in treatment position from the planned one. The position of soft tissue features observed in portal images during gated treatments over several fractions showed a mean variability between 2.6 and 5.7 mm. The intrafraction variability, however, was between 0.6 and 1.4 mm, indicating that most of the variability was

  10. Study of the Welding Electron Gun Optical Properties for Work Piece Imaging

    Czech Academy of Sciences Publication Activity Database

    Vlček, Ivan

    2009-01-01

    Roč. 44, 5-6 (2009), s. 70-72 ISSN 0861-4717 R&D Projects: GA AV ČR KAN300100702 Institutional research plan: CEZ:AV0Z20650511 Keywords : electron beam welding * electron gun * electron optics design Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  11. Observation of superconducting fluxons by transmission electron microscopy: A Fourier space approach to calculate the electron optical phase shifts and images

    International Nuclear Information System (INIS)

    Beleggia, M.; Pozzi, G.

    2001-01-01

    An approach is presented for the calculation of the electron optical phase shift experienced by high-energy electrons in a transmission electron microscope, when they interact with the magnetic field associated with superconducting fluxons in a thin specimen tilted with respect to the beam. It is shown that by decomposing the vector potential in its Fourier components and by calculating the phase shift of each component separately, it is possible to obtain the Fourier transform of the electron optical phase shift, which can be inverted either analytically or numerically. It will be shown how this method can be used to recover the result, previously obtained by the real-space approach, relative to the case of a straight flux tube perpendicular to the specimen surfaces. Then the method is applied to the case of a London fluxon in a thin film, where the bending and the broadening of the magnetic-field lines due to the finite specimen thickness are now correctly taken into account and not treated approximately by means of a parabolic fit. Finally, it will be shown how simple models for the pancake structure of the fluxon can be analyzed within this framework and the main features of electron transmission images predicted

  12. Investigation of runaway electron dissipation in DIII-D using a gamma ray imager

    Science.gov (United States)

    Lvovskiy, A.; Paz-Soldan, C.; Eidietis, N.; Pace, D.; Taussig, D.

    2017-10-01

    We report the findings of a novel gamma ray imager (GRI) to study runaway electron (RE) dissipation in the quiescent regime on the DIII-D tokamak. The GRI measures the bremsstrahlung emission by RE providing information on RE energy spectrum and distribution across a poloidal cross-section. It consists of a lead pinhole camera illuminating a matrix of BGO detectors placed in the DIII-D mid-plane. The number of detectors was recently doubled to provide better spatial resolution and additional detector shielding was implemented to reduce un-collimated gamma flux and increase single-to-noise ratio. Under varying loop voltage, toroidal magnetic field and plasma density, a non-monotonic RE distribution function has been revealed as a result of the interplay between electric field, synchrotron radiation and collisional damping. A fraction of the high-energy RE population grows forming a bump at the RE distribution function while synchrotron radiation decreases. A possible destabilizing effect of Parail-Pogutse instability on the RE population will be also discussed. Work supported by the US DOE under DE-FC02-04ER54698.

  13. A novel biotinylated lipid raft reporter for electron microscopic imaging of plasma membrane microdomains[S

    Science.gov (United States)

    Krager, Kimberly J.; Sarkar, Mitul; Twait, Erik C.; Lill, Nancy L.; Koland, John G.

    2012-01-01

    The submicroscopic spatial organization of cell surface receptors and plasma membrane signaling molecules is readily characterized by electron microscopy (EM) via immunogold labeling of plasma membrane sheets. Although various signaling molecules have been seen to segregate within plasma membrane microdomains, the biochemical identity of these microdomains and the factors affecting their formation are largely unknown. Lipid rafts are envisioned as submicron membrane subdomains of liquid ordered structure with differing lipid and protein constituents that define their specific varieties. To facilitate EM investigation of inner leaflet lipid rafts and the localization of membrane proteins therein, a unique genetically encoded reporter with the dually acylated raft-targeting motif of the Lck kinase was developed. This reporter, designated Lck-BAP-GFP, incorporates green fluorescent protein (GFP) and biotin acceptor peptide (BAP) modules, with the latter allowing its single-step labeling with streptavidin-gold. Lck-BAP-GFP was metabolically biotinylated in mammalian cells, distributed into low-density detergent-resistant membrane fractions, and was readily detected with avidin-based reagents. In EM images of plasma membrane sheets, the streptavidin-gold-labeled reporter was clustered in 20–50 nm microdomains, presumably representative of inner leaflet lipid rafts. The utility of the reporter was demonstrated in an investigation of the potential lipid raft localization of the epidermal growth factor receptor. PMID:22822037

  14. Infrared hot-electron NbN superconducting photodetectors for imaging applications

    International Nuclear Information System (INIS)

    Il'in, K.S.; Gol'tsman, G.N.; Verevkin, A.A.; Sobolewski, Roman

    1999-01-01

    We report an effective quantum efficiency of 340, responsivity >200 A W -1 (>10 4 V W -1 ) and response time of 27±5 ps at temperatures close to the superconducting transition for NbN superconducting hot-electron photodetectors (HEPs) in the near-infrared and optical ranges. Our studies were performed on a few nm thick NbN films deposited on sapphire substrates and patterned into μm-size multibridge detector structures, incorporated into a coplanar transmission line. The time-resolved photoresponse was studied by means of subpicosecond electro-optic sampling with 100 fs wide laser pulses. The quantum efficiency and responsivity studies of our photodetectors were conducted using an amplitude-modulated infrared beam, fibre-optically coupled to the device. The observed picosecond response time and the very high efficiency and sensitivity of the NbN HEPs make them an excellent choice for infrared imaging photodetectors and input optical-to-electrical transducers for superconducting digital circuits. (author)

  15. Quantification of metallic nanoparticle morphology with tilt series imaging by transmission electron microscopy

    Science.gov (United States)

    Dutta, Aniruddha; Yuan, Biao; Clukay, Christopher J.; Grabill, Christopher N.; Heinrich, Helge; Bhattacharya, Aniket; Kuebler, Stephen M.

    2012-02-01

    We report on the quantitative analysis of electrolessly deposited Au and Ag nanoparticles (NPs) on SU8 polymer with the help of High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) in tilt series. Au NPs act as nucleating agents for the electroless deposition of silver. Au NPs were prepared by attachingAu^3+cations to amine functionalized SU8 polymeric surfaces and then reducing it with aqueous NaBH4. The nanoscale morphology of the deposited NPs on the surface of polymer has been studied from the dark field TEM cross sectional images. Ag NPs were deposited on the cross-linked polymeric surface from a silver citrate solution reduced by hydroquinone. HAADF-STEM enables us to determine the distances between the NPs and their exact locations at and near the surface. The particle distribution, sizes and densities provide us with the data necessary to control the parameters for the development of the electroless deposition technique for emerging nanoscale technologies.

  16. Initial Imaging of 7-GeV Electron Beams with OTR/ODR Techniques at APS

    CERN Document Server

    Lumpkin, Alex H; Sereno, Nicholas S; Yao, Chihyuan

    2005-01-01

    The development of nonintercepting (NI) diagnostics continues to be of interest at the Advanced Photon Source (APS) as well as elsewhere. In the three rings of the APS facility we use optical synchrotron radiation generated as the electron beam transits the dipole magnetic fields as an NI mechanism to image the beam during top-up operations. However, in the straight transport lines an alternative method is needed. Optical diffraction radiation (ODR) is under investigation to monitor 7-GeV beam trajectory and potentially transverse shape in the booster-to-storage ring (BTS) beamline during top-up operations. We have performed our initial measurements with an Al blade/mirror that served as an optical transition radiation (OTR) monitor when fully inserted into the beam and as an ODR monitor when the beam passed near the edge. In the case of ODR, appreciable signal is emitted by the metal when gamma times the reduced ODR wavelength is comparable to the impact parameter, where gamma is the Lorentz factor. Visible ...

  17. Development of a daily dosimetric control for radiation therapy using an electronic portal imaging device (EPID)

    International Nuclear Information System (INIS)

    Saboori, Mohammadsaeed

    2015-01-01

    Electronic Portal Imaging Devices (EPIDs) can be used to perform dose measurements during radiation therapy treatments if dedicated calibration and correction procedures are applied. The purpose of this study was to provide a new calibration and correction model for an amorphous silicon (a-Si) EPID for use in transit dose verification of step-and-shoot intensity modulated radiation therapy (IMRT). A model was created in a commercial treatment planning system to calculate the nominal two-dimensional (2D) dose map of each radiation field at the EPID level. The EPID system was calibrated and correction factors were determined using a reference set-up, which consisted a patient phantom and an EPID phantom. The advantage of this method is that for the calibration, the actual beam spectrum is used to mimic a patient measurement. As proof-of-principle, the method was tested for the verification of two 7-field IMRT treatment plans with tumor sites in the head-and-neck and pelvic region. Predicted and measured EPID responses were successfully compared to the nominal data from treatment planning using dose difference maps and gamma analyses. Based on our result it can be concluded that this new method of 2D EPID dosimetry is a potential tool for simple patient treatment fraction dose verification.

  18. Dark-field image contrast in transmission scanning electron microscopy: Effects of substrate thickness and detector collection angle

    Energy Technology Data Exchange (ETDEWEB)

    Woehl, Taylor, E-mail: tjwoehl@umd.edu; Keller, Robert

    2016-12-15

    An annular dark field (ADF) detector was placed beneath a specimen in a field emission scanning electron microscope operated at 30 kV to calibrate detector response to incident beam current, and to create transmission images of gold nanoparticles on silicon nitride (SiN) substrates of various thicknesses. Based on the linear response of the ADF detector diodes to beam current, we developed a method that allowed for direct determination of the percentage of that beam current forward scattered to the ADF detector from the sample, i.e. the transmitted electron (TE) yield. Collection angles for the ADF detector region were defined using a masking aperture above the detector and were systematically varied by changing the sample to detector distance. We found the contrast of the nanoparticles, relative to the SiN substrate, decreased monotonically with decreasing inner exclusion angle and increasing substrate thickness. We also performed Monte Carlo electron scattering simulations, which showed quantitative agreement with experimental contrast associated with the nanoparticles. Together, the experiments and Monte Carlo simulations revealed that the decrease in contrast with decreasing inner exclusion angle was due to a rapid increase in the TE yield of the low atomic number substrate. Nanoparticles imaged at low inner exclusion angles (<150 mrad) and on thick substrates (>50 nm) showed low image contrast in their centers surrounded by a bright high-contrast halo on their edges. This complex image contrast was predicted by Monte Carlo simulations, which we interpreted in terms of mixing of the nominally bright field (BF) and ADF electron signals. Our systematic investigation of inner exclusion angle and substrate thickness effects on ADF t-SEM imaging provides fundamental understanding of the contrast mechanisms for image formation, which in turn suggest practical limitations and optimal imaging conditions for different substrate thicknesses. - Highlights: • Developed a

  19. E4orf1: a novel ligand that improves glucose disposal in cell culture.

    Directory of Open Access Journals (Sweden)

    Emily J Dhurandhar

    Full Text Available Reducing dietary fat intake and excess adiposity, the cornerstones of behavioral treatment of insulin resistance (IR, are marginally successful over the long term. Ad36, a human adenovirus, offers a template to improve IR, independent of dietary fat intake or adiposity. Ad36 increases cellular glucose uptake via a Ras-mediated activation of phosphatidyl inositol 3-kinase(PI3K, and improves hyperglycemia in mice, despite a high-fat diet and without reducing adiposity. Ex-vivo studies suggest that Ad36 improves hyperglycemia in mice by increasing glucose uptake by adipose tissue and skeletal muscle, and by reducing hepatic glucose output. It is impractical to use Ad36 for therapeutic action. Instead, we investigated if the E4orf1 protein of Ad36, mediates its anti-hyperglycemic action. Such a candidate protein may offer an attractive template for therapeutic development. Experiment-1 determined that Ad36 'requires' E4orf1 protein to up-regulate cellular glucose uptake. Ad36 significantly increased glucose uptake in 3T3-L1 preadipocytes, which was abrogated by knocking down E4orf1 with siRNA. Experiment-2 identified E4orf1 as 'sufficient' to up-regulate glucose uptake. 3T3-L1 cells that inducibly express E4orf1, increased glucose uptake in an induction-dependent manner, compared to null vector control cells. E4orf1 up-regulated PI3K pathway and increased abundance of Ras--the obligatory molecule in Ad36-induced glucose uptake. Experiment-3: Signaling studies of cells transiently transfected with E4orf1 or a null vector, revealed that E4orf1 may activate Ras/PI3K pathway by binding to Drosophila discs-large (Dlg1 protein. E4orf1 activated total Ras and, particularly the H-Ras isoform. By mutating the PDZ domain binding motif (PBM of E4orf1, Experiment-4 showed that E4orf1 requires its PBM to increase Ras activation or glucose uptake. Experiment-5: In-vitro, a transient transfection by E4orf1 significantly increased glucose uptake in preadipocytes

  20. E4orf1: a novel ligand that improves glucose disposal in cell culture.

    Science.gov (United States)

    Dhurandhar, Emily J; Dubuisson, Olga; Mashtalir, Nazar; Krishnapuram, Rashmi; Hegde, Vijay; Dhurandhar, Nikhil V

    2011-01-01

    Reducing dietary fat intake and excess adiposity, the cornerstones of behavioral treatment of insulin resistance (IR), are marginally successful over the long term. Ad36, a human adenovirus, offers a template to improve IR, independent of dietary fat intake or adiposity. Ad36 increases cellular glucose uptake via a Ras-mediated activation of phosphatidyl inositol 3-kinase(PI3K), and improves hyperglycemia in mice, despite a high-fat diet and without reducing adiposity. Ex-vivo studies suggest that Ad36 improves hyperglycemia in mice by increasing glucose uptake by adipose tissue and skeletal muscle, and by reducing hepatic glucose output. It is impractical to use Ad36 for therapeutic action. Instead, we investigated if the E4orf1 protein of Ad36, mediates its anti-hyperglycemic action. Such a candidate protein may offer an attractive template for therapeutic development. Experiment-1 determined that Ad36 'requires' E4orf1 protein to up-regulate cellular glucose uptake. Ad36 significantly increased glucose uptake in 3T3-L1 preadipocytes, which was abrogated by knocking down E4orf1 with siRNA. Experiment-2 identified E4orf1 as 'sufficient' to up-regulate glucose uptake. 3T3-L1 cells that inducibly express E4orf1, increased glucose uptake in an induction-dependent manner, compared to null vector control cells. E4orf1 up-regulated PI3K pathway and increased abundance of Ras--the obligatory molecule in Ad36-induced glucose uptake. Experiment-3: Signaling studies of cells transiently transfected with E4orf1 or a null vector, revealed that E4orf1 may activate Ras/PI3K pathway by binding to Drosophila discs-large (Dlg1) protein. E4orf1 activated total Ras and, particularly the H-Ras isoform. By mutating the PDZ domain binding motif (PBM) of E4orf1, Experiment-4 showed that E4orf1 requires its PBM to increase Ras activation or glucose uptake. Experiment-5: In-vitro, a transient transfection by E4orf1 significantly increased glucose uptake in preadipocytes, adipocytes, or

  1. Prostate position relative to pelvic bony anatomy based on intraprostatic gold markers and electronic portal imaging

    International Nuclear Information System (INIS)

    Schallenkamp, John M.; Herman, Michael G.; Kruse, Jon J.; Pisansky, Thomas M.

    2005-01-01

    Purpose: To describe the relative positions and motions of the prostate, pelvic bony anatomy, and intraprostatic gold fiducial markers during daily electronic portal localization of the prostate. Methods and Materials: Twenty prostate cancer patients were treated supine with definitive external radiotherapy according to an on-line target localization protocol using three or four intraprostatic gold fiducial markers and an electronic portal imaging device. Daily pretherapy and through-treatment electronic portal images (EPIs) were obtained for each of four treatment fields. The patients' pelvic bony anatomy, intraprostatic gold markers, and a best visual match to the target (i.e., prostate) were identified on simulation digitally reconstructed radiographs and during daily treatment setup and delivery. These data provided quantitative inter- and intrafractional analysis of prostate motion, its position relative to the bony anatomy, and the individual intraprostatic fiducial markers. Treatment planning margins, with and without on-line localization, were subsequently compared. Results: A total of 22,266 data points were obtained from daily pretherapy and through-treatment EPIs. The pretherapy three-dimensional (3D) average displacement of the fiducial markers, as a surrogate for the prostate, was 5.6 mm, which improved to 2.8 mm after use of the localization protocol. The bony anatomy 3D average displacement was 4.4 mm both before and after localization to the prostate (p = 0.46). Along the superior-inferior (SI), anterior-posterior (AP), and right-left (RL) axes, the average prostate displacement improved from 2.5, 3.7, and 1.9 mm, respectively, before localization to 1.4, 1.6, and 1.1 mm after (all p < 0.001). The pretherapy to through-treatment position of the bony landmarks worsened from 1.7 to 2.5 mm (p < 0.001) in the SI axis, remained statistically unchanged at 2.8 mm (p = 0.39) in the AP axis, and improved from 2.0 to 1.2 mm in the RL axis (p < 0.001). There

  2. Atomic resolution imaging of YAlO{sub 3}: Ce in the chromatic and spherical aberration corrected PICO electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Lei [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Barthel, Juri [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen (Germany); Jia, Chun-Lin [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); School of Electronic and Information Engineering and State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Urban, Knut W., E-mail: k.urban@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich, (Germany); School of Electronic and Information Engineering and State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2017-05-15

    Highlights: • First time resolution of 57 pm atom separations by HRTEM with 200 keV electrons. • Quantification of the image spread by absolute matching of experiment and simulation. • An information limit of 52 pm is deduced from the determined image spread. • Substantial deviations from the bulk structure are observed for the ultra-thin sample. - Abstract: The application of combined chromatic and spherical aberration correction in high-resolution transmission electron microscopy enables a significant improvement of the spatial resolution down to 50 pm. We demonstrate that such a resolution can be achieved in practice at 200 kV. Diffractograms of images of gold nanoparticles on amorphous carbon demonstrate corresponding information transfer. The Y atom pairs in [010] oriented yttrium orthoaluminate are successfully imaged together with the Al and the O atoms. Although the 57 pm pair separation is well demonstrated separations between 55 pm and 80 pm are measured. This observation is tentatively attributed to structural relaxations and surface reconstruction in the very thin samples used. Quantification of the resolution limiting effective image spread is achieved based on an absolute match between experimental and simulated image intensity distributions.

  3. Computer experiments on the imaging of the (111) split crowdion interstitial in tungsten by transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Krakow, W [Xerox Corp., Rochester, N.Y. (USA)

    1978-06-01

    Computer simulated dark-field electron micrographs at atomic resolutions have been generated by calculating the diffuse elastic scattering distribution of short range order objects with the important point being that images are formed from regions of reciprocal space that do not contain Bragg reflections of the perfect crystal. Interpretation of these images in terms of atom positions and atom correlations becomes straightforward and it is a simple matter to distinguish between real structural information and image artifacts produced by the phase contrast mechanism in the electron optical imaging process. In this paper images were calculated under a variety of microscope conditions for a (111) split crowdion interstitial in tungsten which included up to 182 atoms of the surrounding strain field. The effect of specimen orientation, microscope objective lens defocus and the contribution of atoms lying in different shells around the defect have been considered. To aid in image interpretation accompanying diffraction patterns have been computed for different specimen orientations which show either the perfect crystal Bragg diffraction pattern or the diffuse scattering distribution produced by the crowdion defect.

  4. Electron radiography

    Science.gov (United States)

    Merrill, Frank E.; Morris, Christopher

    2005-05-17

    A system capable of performing radiography using a beam of electrons. Diffuser means receive a beam of electrons and diffuse the electrons before they enter first matching quadrupoles where the diffused electrons are focused prior to the diffused electrons entering an object. First imaging quadrupoles receive the focused diffused electrons after the focused diffused electrons have been scattered by the object for focusing the scattered electrons. Collimator means receive the scattered electrons and remove scattered electrons that have scattered to large angles. Second imaging quadrupoles receive the collimated scattered electrons and refocus the collimated scattered electrons and map the focused collimated scattered electrons to transverse locations on an image plane representative of the electrons' positions in the object.

  5. X-ray free electron laser and its application to 3-dimensional imaging of non-crystalline nano-structure

    International Nuclear Information System (INIS)

    Ishikawa, Tetsuya

    2007-01-01

    The Laser in the X-ray region has been anticipated to be realized as a light source to probe the nano-world. Free electron lasers using high energy electron accelerators have been promising the candidates. The finding of the principle of Self-Amplified Spontaneous Emission (SASE) resolved the technological difficulties accompanying the X-ray free electron laser, and the construction of large scale SASE facilities started in western countries. In Japan the construction of an SASE facility started in 2006 to be completed in 2010 at the site of the large synchrotron radiation facility, SPring-8 positioned as a 'critical technology of national importance' by the Japanese government. The principle of the X-ray free electron laser is explained and the outline of the Japanese facility construction plan is presented. Also the application of the X-ray laser to the imaging of non-crystalline nano-structure is introduced. (K.Yoshida)

  6. Techniques for improving material fidelity and contrast consistency in secondary electron mode helium ion microscope (HIM) imaging

    Science.gov (United States)

    Thompson, William; Stern, Lewis; Ferranti, Dave; Huynh, Chuong; Scipioni, Larry; Notte, John; Sanford, Colin

    2010-06-01

    Recent helium ion microscope (HIM) imaging studies have shown the strong sensitivity of HIM induced secondary electron (SE) yields [1] to the sample physical and chemical properties and to its surface topography. This SE yield sensitivity is due to the low recoil energy of the HIM initiated electrons and their resulting short mean free path. Additionally, a material's SE escape probability is modulated by changes in the material's work function and surface potential. Due to the escape electrons' roughly 2eV mean energy and their nanometer range mean free path, HIM SE mode image contrast has significant material and surface sensitivity. The latest generation of HIM has a 0.35 nanometer resolution specification and is equipped with a plasma cleaning process to mitigate the effects of hydrocarbon contamination. However, for surfaces that may have native oxide chemistries influencing the secondary electron yield, a new process of low energy, shallow angle argon sputtering, was evaluated. The intent of this work was to study the effect of removing pre-existing native oxides and any in-situ deposited surface contaminants. We will introduce the sputter yield predictions of two established computer models and the sputter yield and sample modification forecasts of the molecular dynamics program, Kalypso. We will review the experimental technique applied to copper samples and show the copper grain contrast improvement that resulted when argon cleaned samples were imaged in HIM SE mode.

  7. Super-resolution imaging based on the temperature-dependent electron-phonon collision frequency effect of metal thin films

    Science.gov (United States)

    Ding, Chenliang; Wei, Jingsong; Xiao, Mufei

    2018-05-01

    We herein propose a far-field super-resolution imaging with metal thin films based on the temperature-dependent electron-phonon collision frequency effect. In the proposed method, neither fluorescence labeling nor any special properties are required for the samples. The 100 nm lands and 200 nm grooves on the Blu-ray disk substrates were clearly resolved and imaged through a laser scanning microscope of wavelength 405 nm. The spot size was approximately 0.80 μm , and the imaging resolution of 1/8 of the laser spot size was experimentally obtained. This work can be applied to the far-field super-resolution imaging of samples with neither fluorescence labeling nor any special properties.

  8. In Vivo pO2 Imaging of Tumors: Oxymetry with Very Low-Frequency Electron Paramagnetic Resonance.

    Science.gov (United States)

    Epel, Boris; Halpern, Howard J

    2015-01-01

    For over a century, it has been known that tumor hypoxia, regions of a tumor with low levels of oxygenation, are important contributors to tumor resistance to radiation therapy and failure of radiation treatment of cancer. Recently, using novel pulse electron paramagnetic resonance (EPR) oxygen imaging, near absolute images of the partial pressure of oxygen (pO2) in tumors of living animals have been obtained. We discuss here the means by which EPR signals can be obtained in living tissues and tumors. We review development of EPR methods to image the pO2 in tumors and the potential for the pO2 image acquisition in human subjects. © 2015 Elsevier Inc. All rights reserved.

  9. In vivo pO2 imaging of tumors: Oxymetry with very low frequency Electron Paramagnetic Resonance

    Science.gov (United States)

    Epel, Boris; Halpern, Howard J.

    2016-01-01

    For over a century it has been known that tumor hypoxia, regions of a tumor with low levels of oxygenation, are important contributors to tumor resistance to radiation therapy and failure of radiation treatment of cancer. Recently, using novel pulse electron paramagnetic resonance (EPR) oxygen imaging, near absolute images of the partial pressure of oxygen (pO2) in tumors of living animals have been obtained. We discuss here the means by which EPR signals can be obtained in living tissues and tumors. We review development of EPR methods to image the pO2 in tumors and the potential for the pO2 image acquisition in human subjects. PMID:26477263

  10. Phenomena of non-thermal electrons from the X-ray