WorldWideScience

Sample records for source density imaging

  1. Distribution of Fe atom density in a dc magnetron sputtering plasma source measured by laser-induced fluorescence imaging spectroscopy

    Shibagaki, K.; Nafarizal, N.; Sasaki, K.; Toyoda, H.; Iwata, S.; Kato, T.; Tsunashima, S.; Sugai, H.

    2003-10-01

    Magnetron sputtering discharge is widely used as an efficient method for thin film fabrication. In order to achieve the optimized fabrication, understanding of the kinetics in plasmas is essential. In the present work, we measured the density distribution of sputtered Fe atoms using laser-induced fluorescence imaging spectroscopy. A dc magnetron plasma source with a Fe target was used. An area of 20 × 2 mm in front of the target was irradiated by a tunable laser beam having a planar shape. The picture of laser-induced fluorescence on the laser beam was taken using an ICCD camera. In this way, we obtained the two-dimensional image of the Fe atom density. As a result, it has been found that the Fe atom density observed at a distance of several centimeters from the target is higher than that adjacent to the target, when the Ar gas pressure was relatively high. It is suggested from this result that some gas-phase production processes of Fe atoms are available in the plasma. This work has been performed under the 21st Century COE Program by the Ministry of Education, Culture, Sports, Science and Technology in Japan.

  2. High current density ion source

    King, H.J.

    1977-01-01

    A high-current-density ion source with high total current is achieved by individually directing the beamlets from an electron bombardment ion source through screen and accelerator electrodes. The openings in these screen and accelerator electrodes are oriented and positioned to direct the individual beamlets substantially toward a focus point. 3 figures, 1 table

  3. Bedside functional brain imaging in critically-ill children using high-density EEG source modeling and multi-modal sensory stimulation

    Danny Eytan

    2016-01-01

    Full Text Available Acute brain injury is a common cause of death and critical illness in children and young adults. Fundamental management focuses on early characterization of the extent of injury and optimizing recovery by preventing secondary damage during the days following the primary injury. Currently, bedside technology for measuring neurological function is mainly limited to using electroencephalography (EEG for detection of seizures and encephalopathic features, and evoked potentials. We present a proof of concept study in patients with acute brain injury in the intensive care setting, featuring a bedside functional imaging set-up designed to map cortical brain activation patterns by combining high density EEG recordings, multi-modal sensory stimulation (auditory, visual, and somatosensory, and EEG source modeling. Use of source-modeling allows for examination of spatiotemporal activation patterns at the cortical region level as opposed to the traditional scalp potential maps. The application of this system in both healthy and brain-injured participants is demonstrated with modality-specific source-reconstructed cortical activation patterns. By combining stimulation obtained with different modalities, most of the cortical surface can be monitored for changes in functional activation without having to physically transport the subject to an imaging suite. The results in patients in an intensive care setting with anatomically well-defined brain lesions suggest a topographic association between their injuries and activation patterns. Moreover, we report the reproducible application of a protocol examining a higher-level cortical processing with an auditory oddball paradigm involving presentation of the patient's own name. This study reports the first successful application of a bedside functional brain mapping tool in the intensive care setting. This application has the potential to provide clinicians with an additional dimension of information to manage

  4. Dual source CT imaging

    Seidensticker, Peter R.; Hofmann, Lars K.

    2008-01-01

    The introduction of Dual Source Computed Tomography (DSCT) in 2005 was an evolutionary leap in the field of CT imaging. Two x-ray sources operated simultaneously enable heart-rate independent temporal resolution and routine spiral dual energy imaging. The precise delivery of contrast media is a critical part of the contrast-enhanced CT procedure. This book provides an introduction to DSCT technology and to the basics of contrast media administration followed by 25 in-depth clinical scan and contrast media injection protocols. All were developed in consensus by selected physicians on the Dual Source CT Expert Panel. Each protocol is complemented by individual considerations, tricks and pitfalls, and by clinical examples from several of the world's best radiologists and cardiologists. This extensive CME-accredited manual is intended to help readers to achieve consistently high image quality, optimal patient care, and a solid starting point for the development of their own unique protocols. (orig.)

  5. Cardiomagnetic source imaging

    Pesola, Katja

    2000-01-01

    Magnetocardiographic (MCG) source imaging has received increasing interest in recent years. With a high enough localization accuracy of the current sources in the heart, valuable information can be provided, e.g., for the pre-ablative evaluation of arrhythmia patients. Furthermore, preliminary studies indicate that ischemic areas, i.e. areas which are suffering from lack of oxygen, and infarcted regions could be localized from multichannel MCG recordings. In this thesis, the accuracy of cardi...

  6. Imaging Breast Density: Established and Emerging Modalities

    Jeon-Hor Chen

    2015-12-01

    Full Text Available Mammographic density has been proven as an independent risk factor for breast cancer. Women with dense breast tissue visible on a mammogram have a much higher cancer risk than women with little density. A great research effort has been devoted to incorporate breast density into risk prediction models to better estimate each individual’s cancer risk. In recent years, the passage of breast density notification legislation in many states in USA requires that every mammography report should provide information regarding the patient’s breast density. Accurate definition and measurement of breast density are thus important, which may allow all the potential clinical applications of breast density to be implemented. Because the two-dimensional mammography-based measurement is subject to tissue overlapping and thus not able to provide volumetric information, there is an urgent need to develop reliable quantitative measurements of breast density. Various new imaging technologies are being developed. Among these new modalities, volumetric mammographic density methods and three-dimensional magnetic resonance imaging are the most well studied. Besides, emerging modalities, including different x-ray–based, optical imaging, and ultrasound-based methods, have also been investigated. All these modalities may either overcome some fundamental problems related to mammographic density or provide additional density and/or compositional information. The present review article aimed to summarize the current established and emerging imaging techniques for the measurement of breast density and the evidence of the clinical use of these density methods from the literature.

  7. Calcium source (image)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  8. PWFA plasma source - interferometric diagnostics for Li vapor density measurements

    Sivakumaran, V.; Mohandas, K.K.; Singh, Sneha; Ravi Kumar, A.V.

    2015-01-01

    A prototype (40 cm long) plasma source based on Li heat pipe oven has been developed for the Plasma Wakefield Acceleration (PWFA) experiments at IPR (IPR), Gujarat as a part of the ongoing Accelerator Programme. Li vapor in the oven is produced by heating solid Li in helium buffer gas. A uniform column of Li plasma is generated by UV photo ionization (193 nm) of the Li vapor in the heat pipe oven. In these experiments, an accurate measurement of Li vapor density is important as it has got a direct consequence on the plasma electron density. In the present experiment, the vapor density is measured optically by using Hook method (spectrally resolved white light interferometry). The hook like structure formed near the vicinity of the Li 670.8 nm resonance line was recorded with a white light Mach Zehnder interferometer crossed with an imaging spectrograph to estimate the Li vapor density. The vapor density measurements have been carried out as a function of external oven temperature and the He buffer gas pressure. This technique has the advantage of being insensitive to line broadening and line shape, and its high dynamic range even with optically thick absorption line. Here, we present the line integrated Lithium vapor density measurement using Hook method and also compare the same with other optical diagnostic techniques (White light absorption and UV absorption) for Li vapor density measurements. (author)

  9. Current Source Density Estimation for Single Neurons

    Dorottya Cserpán

    2014-03-01

    Full Text Available Recent developments of multielectrode technology made it possible to measure the extracellular potential generated in the neural tissue with spatial precision on the order of tens of micrometers and on submillisecond time scale. Combining such measurements with imaging of single neurons within the studied tissue opens up new experimental possibilities for estimating distribution of current sources along a dendritic tree. In this work we show that if we are able to relate part of the recording of extracellular potential to a specific cell of known morphology we can estimate the spatiotemporal distribution of transmembrane currents along it. We present here an extension of the kernel CSD method (Potworowski et al., 2012 applicable in such case. We test it on several model neurons of progressively complicated morphologies from ball-and-stick to realistic, up to analysis of simulated neuron activity embedded in a substantial working network (Traub et al, 2005. We discuss the caveats and possibilities of this new approach.

  10. Image Makers: Reporters or Sources.

    Petruzzello, Marion C.

    To explore how news sources are used by media to create a social image of women during key suffrage events of 1858, 1920, and 1970, the front page stories of the "New York Times" were reviewed for 1 week prior to and 1 week following each of these events: May 14, 1858, the Eighth National Women's Rights Convention in New York City;…

  11. Random laser illumination: an ideal source for biomedical polarization imaging?

    Carvalho, Mariana T.; Lotay, Amrit S.; Kenny, Fiona M.; Girkin, John M.; Gomes, Anderson S. L.

    2016-03-01

    Imaging applications increasingly require light sources with high spectral density (power over spectral bandwidth. This has led in many cases to the replacement of conventional thermal light sources with bright light-emitting diodes (LEDs), lasers and superluminescent diodes. Although lasers and superluminescent diodes appear to be ideal light sources due to their narrow bandwidth and power, however, in the case of full-field imaging, their spatial coherence leads to coherent artefacts, such as speckle, that corrupt the image. LEDs, in contrast, have lower spatial coherence and thus seem the natural choice, but they have low spectral density. Random Lasers are an unconventional type of laser that can be engineered to provide low spatial coherence with high spectral density. These characteristics makes them potential sources for biological imaging applications where specific absorption and reflection are the characteristics required for state of the art imaging. In this work, a Random Laser (RL) is used to demonstrate speckle-free full-field imaging for polarization-dependent imaging in an epi-illumination configuration. We compare LED and RL illumination analysing the resulting images demonstrating that the RL illumination produces an imaging system with higher performance (image quality and spectral density) than that provided by LEDs.

  12. Diagnostic Spectrometers for High Energy Density X-Ray Sources

    Hudson, L. T.; Henins, A.; Seely, J. F.; Holland, G. E.

    2007-01-01

    A new generation of advanced laser, accelerator, and plasma confinement devices are emerging that are producing extreme states of light and matter that are unprecedented for laboratory study. Examples of such sources that will produce laboratory x-ray emissions with unprecedented characteristics include megajoule-class and ultrafast, ultraintense petawatt laser-produced plasmas; tabletop high-harmonic-generation x-ray sources; high-brightness zeta-pinch and magnetically confined plasma sources; and coherent x-ray free electron lasers and compact inverse-Compton x-ray sources. Characterizing the spectra, time structure, and intensity of x rays emitted by these and other novel sources is critical to assessing system performance and progress as well as pursuing the new and unpredictable physical interactions of interest to basic and applied high-energy-density (HED) science. As these technologies mature, increased emphasis will need to be placed on advanced diagnostic instrumentation and metrology, standard reference data, absolute calibrations and traceability of results.We are actively designing, fabricating, and fielding wavelength-calibrated x-ray spectrometers that have been employed to register spectra from a variety of exotic x-ray sources (electron beam ion trap, electron cyclotron resonance ion source, terawatt pulsed-power-driven accelerator, laser-produced plasmas). These instruments employ a variety of curved-crystal optics, detector technologies, and data acquisition strategies. In anticipation of the trends mentioned above, this paper will focus primarily on optical designs that can accommodate the high background signals produced in HED experiments while also registering their high-energy spectral emissions. In particular, we review the results of recent laboratory testing that explores off-Rowland circle imaging in an effort to reclaim the instrumental resolving power that is increasingly elusive at higher energies when using wavelength

  13. Water Density Raster Images for the Gulf of Maine

    National Oceanic and Atmospheric Administration, Department of Commerce — This geodatabase contains water density raster images for the Gulf of Maine that were interpolated from water density (sigma t or kilograms/ meters cubed) point data...

  14. Transmission imaging with a coded source

    Stoner, W.W.; Sage, J.P.; Braun, M.; Wilson, D.T.; Barrett, H.H.

    1976-01-01

    The conventional approach to transmission imaging is to use a rotating anode x-ray tube, which provides the small, brilliant x-ray source needed to cast sharp images of acceptable intensity. Stationary anode sources, although inherently less brilliant, are more compatible with the use of large area anodes, and so they can be made more powerful than rotating anode sources. Spatial modulation of the source distribution provides a way to introduce detailed structure in the transmission images cast by large area sources, and this permits the recovery of high resolution images, in spite of the source diameter. The spatial modulation is deliberately chosen to optimize recovery of image structure; the modulation pattern is therefore called a ''code.'' A variety of codes may be used; the essential mathematical property is that the code possess a sharply peaked autocorrelation function, because this property permits the decoding of the raw image cast by th coded source. Random point arrays, non-redundant point arrays, and the Fresnel zone pattern are examples of suitable codes. This paper is restricted to the case of the Fresnel zone pattern code, which has the unique additional property of generating raw images analogous to Fresnel holograms. Because the spatial frequency of these raw images are extremely coarse compared with actual holograms, a photoreduction step onto a holographic plate is necessary before the decoded image may be displayed with the aid of coherent illumination

  15. EEG source imaging during two Qigong meditations.

    Faber, Pascal L; Lehmann, Dietrich; Tei, Shisei; Tsujiuchi, Takuya; Kumano, Hiroaki; Pascual-Marqui, Roberto D; Kochi, Kieko

    2012-08-01

    Experienced Qigong meditators who regularly perform the exercises "Thinking of Nothing" and "Qigong" were studied with multichannel EEG source imaging during their meditations. The intracerebral localization of brain electric activity during the two meditation conditions was compared using sLORETA functional EEG tomography. Differences between conditions were assessed using t statistics (corrected for multiple testing) on the normalized and log-transformed current density values of the sLORETA images. In the EEG alpha-2 frequency, 125 voxels differed significantly; all were more active during "Qigong" than "Thinking of Nothing," forming a single cluster in parietal Brodmann areas 5, 7, 31, and 40, all in the right hemisphere. In the EEG beta-1 frequency, 37 voxels differed significantly; all were more active during "Thinking of Nothing" than "Qigong," forming a single cluster in prefrontal Brodmann areas 6, 8, and 9, all in the left hemisphere. Compared to combined initial-final no-task resting, "Qigong" showed activation in posterior areas whereas "Thinking of Nothing" showed activation in anterior areas. The stronger activity of posterior (right) parietal areas during "Qigong" and anterior (left) prefrontal areas during "Thinking of Nothing" may reflect a predominance of self-reference, attention and input-centered processing in the "Qigong" meditation, and of control-centered processing in the "Thinking of Nothing" meditation.

  16. Optimal wave focusing for seismic source imaging

    Bazargani, Farhad

    In both global and exploration seismology, studying seismic sources provides geophysicists with invaluable insight into the physics of earthquakes and faulting processes. One way to characterize the seismic source is to directly image it. Time-reversal (TR) focusing provides a simple and robust solution to the source imaging problem. However, for recovering a well- resolved image, TR requires a full-aperture receiver array that surrounds the source and adequately samples the wavefield. This requirement often cannot be realized in practice. In most source imaging experiments, the receiver geometry, due to the limited aperture and sparsity of the stations, does not allow adequate sampling of the source wavefield. Incomplete acquisition and imbalanced illumination of the imaging target limit the resolving power of the TR process. The main focus of this thesis is to offer an alternative approach to source imaging with the goal of mitigating the adverse effects of incomplete acquisition on the TR modeling. To this end, I propose a new method, named Backus-Gilbert (BG) source imaging, to optimally focus the wavefield onto the source position using a given receiver geometry. I first introduce BG as a method for focusing waves in acoustic media at a desired location and time. Then, by exploiting the source-receiver reciprocity of the Green function and the linearity of the problem, I show that BG focusing can be adapted and used as a source-imaging tool. Following this, I generalize the BG theory for elastic waves. Applying BG formalism for source imaging requires a model for the wave propagation properties of the earth and an estimate of the source location. Using numerical tests, I next examine the robustness and sensitivity of the proposed method with respect to errors in the earth model, uncertainty in the source location, and noise in data. The BG method can image extended sources as well as point sources. It can also retrieve the source mechanism. These features of

  17. Multi-Source Image Analysis.

    1979-12-01

    These collections were taken to show the advantages made available to the inter- preter. In a military operation, however, often little or no in- situ ...The large body of water labeled "W" on each image represents the Agua Hedionda lagoon. East of the lagoon the area is primarily agricultural with a...power plant located in the southeast corner of the image. West of the Agua Hedionda lagoon is Carlsbad, California. Damp ground is labelled "Dg" on the

  18. Discharge regimes and density jumps in a helicon plasma source

    Shinohara, S.; Yonekura, K.

    1999-01-01

    A high density plasma source using a helicon wave is becoming very attractive in plasma processing and confinement devices. In the previous work, the characteristics of this wave and plasma performance with diameters of 5 and 45 cm have been studied, and the helicon wave was only observed after the density jump. Recently, density jumps from the low to high electron densities with a level of 10 13 cm -3 were investigated by changing the antenna wavenumber spectrum, and the obtained results were compared with the inductively coupled plasma (ICP). However, the mechanisms of density jumps and plasma production are still open questions to be answered. Here, the authors try to investigate the discharge regimes and density jumps in a helicon plasma source, by changing the antenna wavenumber spectrum. For he case of the parallel current directions in the antenna, where the low wavenumber spectrum part is large, the density jump was observed with the low RF input power of P in < 300 W regardless of the magnetic field. On the other hand, for the case of the opposite directions, where the low wavenumber spectrum part is small, the threshold power to obtain the jump became high with the increase in the magnetic field. This can be understood from the dispersion relation of the helicon wave. The wave structures and the dispersion relations in the discharge modes will be also shown

  19. Image authentication using distributed source coding.

    Lin, Yao-Chung; Varodayan, David; Girod, Bernd

    2012-01-01

    We present a novel approach using distributed source coding for image authentication. The key idea is to provide a Slepian-Wolf encoded quantized image projection as authentication data. This version can be correctly decoded with the help of an authentic image as side information. Distributed source coding provides the desired robustness against legitimate variations while detecting illegitimate modification. The decoder incorporating expectation maximization algorithms can authenticate images which have undergone contrast, brightness, and affine warping adjustments. Our authentication system also offers tampering localization by using the sum-product algorithm.

  20. Source-space ICA for MEG source imaging.

    Jonmohamadi, Yaqub; Jones, Richard D

    2016-02-01

    One of the most widely used approaches in electroencephalography/magnetoencephalography (MEG) source imaging is application of an inverse technique (such as dipole modelling or sLORETA) on the component extracted by independent component analysis (ICA) (sensor-space ICA + inverse technique). The advantage of this approach over an inverse technique alone is that it can identify and localize multiple concurrent sources. Among inverse techniques, the minimum-variance beamformers offer a high spatial resolution. However, in order to have both high spatial resolution of beamformer and be able to take on multiple concurrent sources, sensor-space ICA + beamformer is not an ideal combination. We propose source-space ICA for MEG as a powerful alternative approach which can provide the high spatial resolution of the beamformer and handle multiple concurrent sources. The concept of source-space ICA for MEG is to apply the beamformer first and then singular value decomposition + ICA. In this paper we have compared source-space ICA with sensor-space ICA both in simulation and real MEG. The simulations included two challenging scenarios of correlated/concurrent cluster sources. Source-space ICA provided superior performance in spatial reconstruction of source maps, even though both techniques performed equally from a temporal perspective. Real MEG from two healthy subjects with visual stimuli were also used to compare performance of sensor-space ICA and source-space ICA. We have also proposed a new variant of minimum-variance beamformer called weight-normalized linearly-constrained minimum-variance with orthonormal lead-field. As sensor-space ICA-based source reconstruction is popular in EEG and MEG imaging, and given that source-space ICA has superior spatial performance, it is expected that source-space ICA will supersede its predecessor in many applications.

  1. Referenceless Prediction of Perceptual Fog Density and Perceptual Image Defogging.

    Choi, Lark Kwon; You, Jaehee; Bovik, Alan Conrad

    2015-11-01

    We propose a referenceless perceptual fog density prediction model based on natural scene statistics (NSS) and fog aware statistical features. The proposed model, called Fog Aware Density Evaluator (FADE), predicts the visibility of a foggy scene from a single image without reference to a corresponding fog-free image, without dependence on salient objects in a scene, without side geographical camera information, without estimating a depth-dependent transmission map, and without training on human-rated judgments. FADE only makes use of measurable deviations from statistical regularities observed in natural foggy and fog-free images. Fog aware statistical features that define the perceptual fog density index derive from a space domain NSS model and the observed characteristics of foggy images. FADE not only predicts perceptual fog density for the entire image, but also provides a local fog density index for each patch. The predicted fog density using FADE correlates well with human judgments of fog density taken in a subjective study on a large foggy image database. As applications, FADE not only accurately assesses the performance of defogging algorithms designed to enhance the visibility of foggy images, but also is well suited for image defogging. A new FADE-based referenceless perceptual image defogging, dubbed DEnsity of Fog Assessment-based DEfogger (DEFADE) achieves better results for darker, denser foggy images as well as on standard foggy images than the state of the art defogging methods. A software release of FADE and DEFADE is available online for public use: http://live.ece.utexas.edu/research/fog/index.html.

  2. Coded aperture imaging of alpha source spatial distribution

    Talebitaher, Alireza; Shutler, Paul M.E.; Springham, Stuart V.; Rawat, Rajdeep S.; Lee, Paul

    2012-01-01

    The Coded Aperture Imaging (CAI) technique has been applied with CR-39 nuclear track detectors to image alpha particle source spatial distributions. The experimental setup comprised: a 226 Ra source of alpha particles, a laser-machined CAI mask, and CR-39 detectors, arranged inside a vacuum enclosure. Three different alpha particle source shapes were synthesized by using a linear translator to move the 226 Ra source within the vacuum enclosure. The coded mask pattern used is based on a Singer Cyclic Difference Set, with 400 pixels and 57 open square holes (representing ρ = 1/7 = 14.3% open fraction). After etching of the CR-39 detectors, the area, circularity, mean optical density and positions of all candidate tracks were measured by an automated scanning system. Appropriate criteria were used to select alpha particle tracks, and a decoding algorithm applied to the (x, y) data produced the de-coded image of the source. Signal to Noise Ratio (SNR) values obtained for alpha particle CAI images were found to be substantially better than those for corresponding pinhole images, although the CAI-SNR values were below the predictions of theoretical formulae. Monte Carlo simulations of CAI and pinhole imaging were performed in order to validate the theoretical SNR formulae and also our CAI decoding algorithm. There was found to be good agreement between the theoretical formulae and SNR values obtained from simulations. Possible reasons for the lower SNR obtained for the experimental CAI study are discussed.

  3. DEIMOS – an Open Source Image Database

    M. Blazek

    2011-12-01

    Full Text Available The DEIMOS (DatabasE of Images: Open Source is created as an open-source database of images and videos for testing, verification and comparing of various image and/or video processing techniques such as enhancing, compression and reconstruction. The main advantage of DEIMOS is its orientation to various application fields – multimedia, television, security, assistive technology, biomedicine, astronomy etc. The DEIMOS is/will be created gradually step-by-step based upon the contributions of team members. The paper is describing basic parameters of DEIMOS database including application examples.

  4. Open source tools for fluorescent imaging.

    Hamilton, Nicholas A

    2012-01-01

    As microscopy becomes increasingly automated and imaging expands in the spatial and time dimensions, quantitative analysis tools for fluorescent imaging are becoming critical to remove both bottlenecks in throughput as well as fully extract and exploit the information contained in the imaging. In recent years there has been a flurry of activity in the development of bio-image analysis tools and methods with the result that there are now many high-quality, well-documented, and well-supported open source bio-image analysis projects with large user bases that cover essentially every aspect from image capture to publication. These open source solutions are now providing a viable alternative to commercial solutions. More importantly, they are forming an interoperable and interconnected network of tools that allow data and analysis methods to be shared between many of the major projects. Just as researchers build on, transmit, and verify knowledge through publication, open source analysis methods and software are creating a foundation that can be built upon, transmitted, and verified. Here we describe many of the major projects, their capabilities, and features. We also give an overview of the current state of open source software for fluorescent microscopy analysis and the many reasons to use and develop open source methods. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Density of Resonance Neutrons in Hydrogenous Media Near the Source

    Broda, E.

    1944-07-01

    This report was written by D.V. Booker, E. Broda and L. Kowarski at the Cavendish Laboratory (Cambridge) in January 1944 and is about the density of resonance neutrons in hydrogenous media near the source. Neutron-absorbing properties of a medium sometimes cannot be studied by the usual density integration technique because the amount of medium, or the intensity far from the source is insufficient. In such cases many useful deductions can be made from single-point activation measurements in a medium of known behaviour provided the differences between the scattering properties of the two media are negligible, insofar as they influence the observed activations, or can be allowed for. The relevant properties of a hydrogenous medium are discussed in this report and the activation of resonance detectors in H{sub 3}BO{sub 3} is compared to the activation in C{sub 10}H{sub 8}, used as a reference medium. (nowak)

  6. Density imaging of volcanos with atmospheric muons

    Fehr , F.

    2011-01-01

    collaboration : TOMUVOL; International audience; Their capability to penetrate large depths of material renders high-energy atmospheric muons a unique probe for geophysical explorations. Provided the topography of the target is known, the measurement of the attenuation of the muon flux permits the cartography of matter density distributions revealing spatial and possibly also temporal variations in extended geological structures. A Collaboration between volcanologists, astroparticle- and part...

  7. Electromagnetic considerations for RF current density imaging [MRI technique].

    Scott, G C; Joy, M G; Armstrong, R L; Henkelman, R M

    1995-01-01

    Radio frequency current density imaging (RF-CDI) is a recent MRI technique that can image a Larmor frequency current density component parallel to B(0). Because the feasibility of the technique was demonstrated only for homogeneous media, the authors' goal here is to clarify the electromagnetic assumptions and field theory to allow imaging RF currents in heterogeneous media. The complete RF field and current density imaging problem is posed. General solutions are given for measuring lab frame magnetic fields from the rotating frame magnetic field measurements. For the general case of elliptically polarized fields, in which current and magnetic field components are not in phase, one can obtain a modified single rotation approximation. Sufficient information exists to image the amplitude and phase of the RF current density parallel to B(0) if the partial derivative in the B(0) direction of the RF magnetic field (amplitude and phase) parallel to B(0) is much smaller than the corresponding current density component. The heterogeneous extension was verified by imaging conduction and displacement currents in a phantom containing saline and pure water compartments. Finally, the issues required to image eddy currents are presented. Eddy currents within a sample will distort both the transmitter coil reference system, and create measurable rotating frame magnetic fields. However, a three-dimensional electro-magnetic analysis will be required to determine how the reference system distortion affects computed eddy current images.

  8. OSIRIX: open source multimodality image navigation software

    Rosset, Antoine; Pysher, Lance; Spadola, Luca; Ratib, Osman

    2005-04-01

    The goal of our project is to develop a completely new software platform that will allow users to efficiently and conveniently navigate through large sets of multidimensional data without the need of high-end expensive hardware or software. We also elected to develop our system on new open source software libraries allowing other institutions and developers to contribute to this project. OsiriX is a free and open-source imaging software designed manipulate and visualize large sets of medical images: http://homepage.mac.com/rossetantoine/osirix/

  9. Bayesian image processing of data from fuzzy pattern sources

    Liang, Z.; Hart, H.

    1986-01-01

    In some radioisotopic organ image applications, a priori or supplementary source information may exist and can be characterized in terms of probability density functions P (phi) of the source elements {phi/sub j/} = phi (where phi/sub j/ (j = 1,2,..α) is the estimated average photon emission in voxel j per unit time at t = 0). For example, in cardiac imaging studies it is possible to evaluate the radioisotope concentration of the blood filling the cardiac chambers independently as a function of time by peripheral measurement. The blood concentration information in effect serves to limit amplitude uncertainty to the chamber boundary voxels and thus reduces the extent of amplitude ambiguities in the overall cardiac imaging reconstruction. The a priori or supplementary information may more generally be spatial, amplitude-dependent probability distributions P(phi), fuzzy patterns superimposed upon a background

  10. Stereoscopic radiographic images with gamma source encoding

    Strocovsky, S.G.; Otero, D

    2012-01-01

    Conventional radiography with X-ray tube has several drawbacks, as the compromise between the size of the focal spot and the fluence. The finite dimensions of the focal spot impose a limit to the spatial resolution. Gamma radiography uses gamma-ray sources which surpass in size, portability and simplicity to X-ray tubes. However, its low intrinsic fluence forces to use extended sources that also degrade the spatial resolution. In this work, we show the principles of a new radiographic technique that overcomes the limitations associated with the finite dimensions of X-ray sources, and that offers additional benefits to conventional techniques. The new technique called coding source imaging (CSI), is based on the use of extended sources, edge-encoding of radiation and differential detection. The mathematical principles and the method of images reconstruction with the new proposed technique are explained in the present work. Analytical calculations were made to determine the maximum spatial resolution and the variables on which it depends. The CSI technique was tested by means of Monte Carlo simulations with sets of spherical objects. We show that CSI has stereoscopic capabilities and it can resolve objects smaller than the source size. The CSI decoding algorithm reconstructs simultaneously four different projections from the same object, while conventional radiography produces only one projection per acquisition. Projections are located in separate image fields on the detector plane. Our results show it is possible to apply an extremely simple radiographic technique with extended sources, and get 3D information of the attenuation coefficient distribution for simple geometry objects in a single acquisition. The results are promising enough to evaluate the possibility of future research with more complex objects typical of medical diagnostic radiography and industrial gamma radiography (author)

  11. Automatic breast tissue density estimation scheme in digital mammography images

    Menechelli, Renan C.; Pacheco, Ana Luisa V.; Schiabel, Homero

    2017-03-01

    Cases of breast cancer have increased substantially each year. However, radiologists are subject to subjectivity and failures of interpretation which may affect the final diagnosis in this examination. The high density features in breast tissue are important factors related to these failures. Thus, among many functions some CADx (Computer-Aided Diagnosis) schemes are classifying breasts according to the predominant density. In order to aid in such a procedure, this work attempts to describe automated software for classification and statistical information on the percentage change in breast tissue density, through analysis of sub regions (ROIs) from the whole mammography image. Once the breast is segmented, the image is divided into regions from which texture features are extracted. Then an artificial neural network MLP was used to categorize ROIs. Experienced radiologists have previously determined the ROIs density classification, which was the reference to the software evaluation. From tests results its average accuracy was 88.7% in ROIs classification, and 83.25% in the classification of the whole breast density in the 4 BI-RADS density classes - taking into account a set of 400 images. Furthermore, when considering only a simplified two classes division (high and low densities) the classifier accuracy reached 93.5%, with AUC = 0.95.

  12. Magneto-optical imaging of transport current densities in superconductors

    Crabtree, G.W.; Welp, U.; Gunter, D.O.; Zhong, W.; Balachandran, U.; Haldar, P.; Sokolowski, R.S.; Vlasko-Vlasov, V.K.; Nikitenko, V.I.

    1995-01-01

    Direct imaging of the paths of transport currents in superconductors creates many new possibilities for exploring the basic features of vortex pinning mechanisms and for improving the performance of superconducting materials. A technique for imaging the path and magnitude of the transport current density flowing in superconductors is described. Results are given for a 37-filament BSCCO 2223 powder-in-tube wire, showing a highly inhomogeneous current path within the filaments

  13. Computerized image analysis: estimation of breast density on mammograms

    Zhou, Chuan; Chan, Heang-Ping; Petrick, Nicholas; Sahiner, Berkman; Helvie, Mark A.; Roubidoux, Marilyn A.; Hadjiiski, Lubomir M.; Goodsitt, Mitchell M.

    2000-06-01

    An automated image analysis tool is being developed for estimation of mammographic breast density, which may be useful for risk estimation or for monitoring breast density change in a prevention or intervention program. A mammogram is digitized using a laser scanner and the resolution is reduced to a pixel size of 0.8 mm X 0.8 mm. Breast density analysis is performed in three stages. First, the breast region is segmented from the surrounding background by an automated breast boundary-tracking algorithm. Second, an adaptive dynamic range compression technique is applied to the breast image to reduce the range of the gray level distribution in the low frequency background and to enhance the differences in the characteristic features of the gray level histogram for breasts of different densities. Third, rule-based classification is used to classify the breast images into several classes according to the characteristic features of their gray level histogram. For each image, a gray level threshold is automatically determined to segment the dense tissue from the breast region. The area of segmented dense tissue as a percentage of the breast area is then estimated. In this preliminary study, we analyzed the interobserver variation of breast density estimation by two experienced radiologists using BI-RADS lexicon. The radiologists' visually estimated percent breast densities were compared with the computer's calculation. The results demonstrate the feasibility of estimating mammographic breast density using computer vision techniques and its potential to improve the accuracy and reproducibility in comparison with the subjective visual assessment by radiologists.

  14. Local breast density assessment using reacquired mammographic images.

    García, Eloy; Diaz, Oliver; Martí, Robert; Diez, Yago; Gubern-Mérida, Albert; Sentís, Melcior; Martí, Joan; Oliver, Arnau

    2017-08-01

    The aim of this paper is to evaluate the spatial glandular volumetric tissue distribution as well as the density measures provided by Volpara™ using a dataset composed of repeated pairs of mammograms, where each pair was acquired in a short time frame and in a slightly changed position of the breast. We conducted a retrospective analysis of 99 pairs of repeatedly acquired full-field digital mammograms from 99 different patients. The commercial software Volpara™ Density Maps (Volpara Solutions, Wellington, New Zealand) is used to estimate both the global and the local glandular tissue distribution in each image. The global measures provided by Volpara™, such as breast volume, volume of glandular tissue, and volumetric breast density are compared between the two acquisitions. The evaluation of the local glandular information is performed using histogram similarity metrics, such as intersection and correlation, and local measures, such as statistics from the difference image and local gradient correlation measures. Global measures showed a high correlation (breast volume R=0.99, volume of glandular tissue R=0.94, and volumetric breast density R=0.96) regardless the anode/filter material. Similarly, histogram intersection and correlation metric showed that, for each pair, the images share a high degree of information. Regarding the local distribution of glandular tissue, small changes in the angle of view do not yield significant differences in the glandular pattern, whilst changes in the breast thickness between both acquisition affect the spatial parenchymal distribution. This study indicates that Volpara™ Density Maps is reliable in estimating the local glandular tissue distribution and can be used for its assessment and follow-up. Volpara™ Density Maps is robust to small variations of the acquisition angle and to the beam energy, although divergences arise due to different breast compression conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Methodology to evaluation of the density in radiographic image

    Louzada, M.J.Q.; Pela, C.A.; Belangero, W.D.; Santos-Pinto, R.

    1998-01-01

    This study was designed in order to optimize the optical densitometry technique in radiographic images by the setorization of the characteristic curves of the radiographic films. We used 24 radiographs of a stepped aluminium wedge that were taken without rigorous control development and manually revealed. The densitometric values of the steps images and its thickness, for each radiographic, was utilized to generate its particular mathematics expressions that represent its characteristic densitometric curves and then it were used for setorization. The densitometric values were obtained by a Macbeth TD528 densitometer. The study showed an optimization in the representation of the relationship between the optical density of the steps images of the wedge and its correspondent thickness, provided by the setorization, with mean square error around 10 -5 . This optimization will allow the use of this methodology in quantitative evaluations of bone mass, by radiographic images. (author)

  16. The impact of mammographic imaging systems on density measurement

    Damases, Christine N.; Brennan, Patrick C.; McEntee, Mark F.

    2015-03-01

    The purpose of this study is to investigate whether having a mammogram on differing manufacturer equipment will affect a woman's breast density (BD) measurement. The data set comprised of 40 cases, each containing a combined image of the left craniocaudal (LCC) and left mediolateral oblique (LMLO). These images were obtained from 20 women age between 42-89 years. The images were acquired on two imaging systems (GE and Hologic) one year apart. Volumetric BD was assessed by using Volpara Density Grade (VDG) and average BD% (AvBD%). Twenty American Board of Radiology (ABR) examiners assessed the same images using the BIRADS BD scale 1-4. Statistical comparisons were performed on the means using Mann-Whitney, on correlation using Spearman's rank coefficient of correlation and agreement using Cohen's Kappa. The absolute median BIRADS difference between GE and Hologic was 0.225 (2.00 versus 2.00; pperfect agreement for VDG (κ=0.933; p<0.001).

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

    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.

  18. Quantitative imaging of cation adsorption site densities in undisturbed soil

    Keck, Hannes; Strobel, Bjarne W.; Gustafsson, Jon-Petter; Koestel, John

    2017-04-01

    The vast majority of present soil system models assume a homogeneous distribution and accessibility of cation adsorption sites (CAS) within soil structural units like e.g. soil horizons. This is however in conflict with several recent studies finding that CAS in soils are not uniformly but patchily distributed at and below the cm-scale. It is likely that the small-scale distribution of CAS has significant impact on the performance of these models. However, systematic approaches to map CAS densities in undisturbed soil with 3-D resolution that could lead to respective model improvements are still lacking. We therefore investigated the 3-D distribution of the CAS in undisturbed soils using X-ray scanning and barium ions as a contrast agent. We appraised the validity of the approach by comparing X-ray image-derived cation exchange coefficients (CEC) with ones obtained using the ammonium acetate method. In the process, we evaluated whether there were larger CAS concentrations at aggregate and biopore boundaries as it is often hypothesized. We sampled eight small soil cores (approx. 10 ccm) from different locations with contrasting soil texture and organic matter contents. The samples were first saturated with a potassium chloride solution (0.1 mol per liter), whereupon a 3-D X-ray image was taken. Then, the potassium chloride solution was flushed out with a barium chloride solution (0.3 mol per liter) with barium replacing the potassium from the CAS due to its larger exchange affinity. After X-ray images as well as electrical conductivity in the effluent indicated that the entire sample had been saturated with the barium chloride, the sample was again rinsed using the potassium chloride solution. When the rinsing was complete a final 3-D X-ray image was acquired. The difference images between final and initial 3-D X-ray images were interpreted as depicting the adsorbed barium as the density of barium exceeds the one of potassium by more than 2 times. The X-ray image

  19. Extraction of density distributions and particle locations from hologram images

    Ikeda, Koh; Okamoto, Koji; Kato, Fumitake; Shimizu, Isao.

    1996-01-01

    In this study, the simultaneous measurement technique for three-dimensional density and three-dimensional velocity distributions was evaluated. The Holographic Particle Image Velocimetry (HPIV) was the technique to record the three-dimensional position of the tracer particle on the hologram. In the hologram, the interferogram between reference beam and particle scattering were recorded. When there were density distributions in the interrogation region, the plane optical wave may be modulated because of the difference of the refraction indices. Then, both of the plane wave modulated by density and the spherical wave by particle scatter were interfered with the reference beam, being recorded on the hologram. With reconstructing the hologram, the both of the modulated plane wave and spherical wave were reconstructed. Since the plane wave and spherical wave had low and high frequency, respectively, the plane wave was reconstructed with the low-pass filter, resulting in the information of the density distributions to be obtained. With the high-pass filter, the particle three-dimensional positions was determined, i.e., the same procedure with the original HPIV technique. In the experiment, a jet of carbon-dioxide into air with mist were measured. Both mist particle position and the fringe shift caused by the density distribution were well observed, showing the effectiveness of the proposed technique. (author)

  20. Polyquant CT: direct electron and mass density reconstruction from a single polyenergetic source

    Mason, Jonathan H.; Perelli, Alessandro; Nailon, William H.; Davies, Mike E.

    2017-11-01

    Quantifying material mass and electron density from computed tomography (CT) reconstructions can be highly valuable in certain medical practices, such as radiation therapy planning. However, uniquely parameterising the x-ray attenuation in terms of mass or electron density is an ill-posed problem when a single polyenergetic source is used with a spectrally indiscriminate detector. Existing approaches to single source polyenergetic modelling often impose consistency with a physical model, such as water-bone or photoelectric-Compton decompositions, which will either require detailed prior segmentation or restrictive energy dependencies, and may require further calibration to the quantity of interest. In this work, we introduce a data centric approach to fitting the attenuation with piecewise-linear functions directly to mass or electron density, and present a segmentation-free statistical reconstruction algorithm for exploiting it, with the same order of complexity as other iterative methods. We show how this allows both higher accuracy in attenuation modelling, and demonstrate its superior quantitative imaging, with numerical chest and metal implant data, and validate it with real cone-beam CT measurements.

  1. Dense Plasma Focus - From Alternative Fusion Source to Versatile High Energy Density Plasma Source for Plasma Nanotechnology

    Rawat, R. S.

    2015-03-01

    The dense plasma focus (DPF), a coaxial plasma gun, utilizes pulsed high current electrical discharge to heat and compress the plasma to very high density and temperature with energy densities in the range of 1-10 × 1010 J/m3. The DPF device has always been in the company of several alternative magnetic fusion devices as it produces intense fusion neutrons. Several experiments conducted on many different DPF devices ranging over several order of storage energy have demonstrated that at higher storage energy the neutron production does not follow I4 scaling laws and deteriorate significantly raising concern about the device's capability and relevance for fusion energy. On the other hand, the high energy density pinch plasma in DPF device makes it a multiple radiation source of ions, electron, soft and hard x-rays, and neutrons, making it useful for several applications in many different fields such as lithography, radiography, imaging, activation analysis, radioisotopes production etc. Being a source of hot dense plasma, strong shockwave, intense energetic beams and radiation, etc, the DPF device, additionally, shows tremendous potential for applications in plasma nanoscience and plasma nanotechnology. In the present paper, the key features of plasma focus device are critically discussed to understand the novelties and opportunities that this device offers in processing and synthesis of nanophase materials using, both, the top-down and bottom-up approach. The results of recent key experimental investigations performed on (i) the processing and modification of bulk target substrates for phase change, surface reconstruction and nanostructurization, (ii) the nanostructurization of PLD grown magnetic thin films, and (iii) direct synthesis of nanostructured (nanowire, nanosheets and nanoflowers) materials using anode target material ablation, ablated plasma and background reactive gas based synthesis and purely gas phase synthesis of various different types of

  2. Dense Plasma Focus - From Alternative Fusion Source to Versatile High Energy Density Plasma Source for Plasma Nanotechnology

    Rawat, R S

    2015-01-01

    The dense plasma focus (DPF), a coaxial plasma gun, utilizes pulsed high current electrical discharge to heat and compress the plasma to very high density and temperature with energy densities in the range of 1-10 × 10 10 J/m 3 . The DPF device has always been in the company of several alternative magnetic fusion devices as it produces intense fusion neutrons. Several experiments conducted on many different DPF devices ranging over several order of storage energy have demonstrated that at higher storage energy the neutron production does not follow I 4 scaling laws and deteriorate significantly raising concern about the device's capability and relevance for fusion energy. On the other hand, the high energy density pinch plasma in DPF device makes it a multiple radiation source of ions, electron, soft and hard x-rays, and neutrons, making it useful for several applications in many different fields such as lithography, radiography, imaging, activation analysis, radioisotopes production etc. Being a source of hot dense plasma, strong shockwave, intense energetic beams and radiation, etc, the DPF device, additionally, shows tremendous potential for applications in plasma nanoscience and plasma nanotechnology. In the present paper, the key features of plasma focus device are critically discussed to understand the novelties and opportunities that this device offers in processing and synthesis of nanophase materials using, both, the top-down and bottom-up approach. The results of recent key experimental investigations performed on (i) the processing and modification of bulk target substrates for phase change, surface reconstruction and nanostructurization, (ii) the nanostructurization of PLD grown magnetic thin films, and (iii) direct synthesis of nanostructured (nanowire, nanosheets and nanoflowers) materials using anode target material ablation, ablated plasma and background reactive gas based synthesis and purely gas phase synthesis of various different types of

  3. Detection of High-Density Crowds in Aerial Images Using Texture Classification

    Oliver Meynberg

    2016-06-01

    Full Text Available Automatic crowd detection in aerial images is certainly a useful source of information to prevent crowd disasters in large complex scenarios of mass events. A number of publications employ regression-based methods for crowd counting and crowd density estimation. However, these methods work only when a correct manual count is available to serve as a reference. Therefore, it is the objective of this paper to detect high-density crowds in aerial images, where counting– or regression–based approaches would fail. We compare two texture–classification methodologies on a dataset of aerial image patches which are grouped into ranges of different crowd density. These methodologies are: (1 a Bag–of–words (BoW model with two alternative local features encoded as Improved Fisher Vectors and (2 features based on a Gabor filter bank. Our results show that a classifier using either BoW or Gabor features can detect crowded image regions with 97% classification accuracy. In our tests of four classes of different crowd-density ranges, BoW–based features have a 5%–12% better accuracy than Gabor.

  4. PIII Plasma Density Enhancement by a New DC Power Source

    Lopez-Callejas, R.; Godoy-Cabrera, O. G.; Granda-Gutierrez, E. E.; Piedad-Beneitez, A. de la; Munoz-Castro, A. E.; Valencia A, R.; Barocio, S. R.; Mercado-Cabrera, A.; Pena-Eguiluz, R.

    2006-01-01

    In practical terms, those plasmas produced by a DC voltage power supply do not attain densities above the 108 to 109 cm-3 band. Here we present a power supply, controlled in current and voltage, which has been successfully designed and constructed delivering plasma densities in the orders of 109 - 1010 cm-3. Its experimental performance test was conducted within one toroidal and one cylindrical chambers capable of 29 and 35 litres, respectively, using nitrogen gas. The DC plasma was characterized by a double electric probe. Several physical phenomena present in the PIII process have been keenly investigated including plasma sheath dynamics, interaction of plasma and surface, etc. In this paper we analyze the effect of the implantation voltage, plasma density and pulse time in the PIII average heating power and fluence density

  5. Extraction of density distributions and particle locations from hologram images

    Okamoto, Koji; Ikeda, Koh; Madarame, Haruki [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    1996-10-01

    In this study, the simultaneous measurement technique for three-dimensional density and three-dimensional velocity distributions was evaluated. The Holographic Particle Image Velocimetry (HPIV) was the technique to record the three-dimensional position of the tracer particle on the hologram. When there were density distributions in the interrogation region, the plane optical wave may be modulated because of the difference of the refraction indices. Then, both of the plane wave modulated by density and the spherical wave by particle scatter were interfered with the reference beam, being recorded on the hologram. With reconstructing the hologram, the both of the modulated plane wave and spherical wave were reconstructed. Since the plane wave and spherical wave had low and high frequency, respectively, the two information could be separated using low-pass and high-pass filter. In the experiment, a jet of carbon-dioxide into air with mist were measured. Both mist particle position and the fringe shift caused by the density distribution were well observed, showing the effectiveness of the proposed technique. (author)

  6. Magnetic resonance electrical impedance tomography (MREIT): conductivity and current density imaging

    Seo, Jin Keun; Kwon, Ohin; Woo, Eung Je

    2005-01-01

    This paper reviews the latest impedance imaging technique called Magnetic Resonance Electrical Impedance Tomography (MREIT) providing information on electrical conductivity and current density distributions inside an electrically conducting domain such as the human body. The motivation for this research is explained by discussing conductivity changes related with physiological and pathological events, electromagnetic source imaging and electromagnetic stimulations. We briefly summarize the related technique of Electrical Impedance Tomography (EIT) that deals with cross-sectional image reconstructions of conductivity distributions from boundary measurements of current-voltage data. Noting that EIT suffers from the ill-posed nature of the corresponding inverse problem, we introduce MREIT as a new conductivity imaging modality providing images with better spatial resolution and accuracy. MREIT utilizes internal information on the induced magnetic field in addition to the boundary current-voltage measurements to produce three-dimensional images of conductivity and current density distributions. Mathematical theory, algorithms, and experimental methods of current MREIT research are described. With numerous potential applications in mind, future research directions in MREIT are proposed

  7. Experimental investigation of statistical density function of decaying radioactive sources

    Salma, I.; Zemplen-Papp, E.

    1991-01-01

    The validity of the Poisson and the λ P(k) modified Poisson statistical density functions of observing k events in a short time interval is investigated experimentally in radioactive decay detection for various measuring times. The experiments to measure radioactive decay were performed with 89m Y, using a multichannel analyzer. According to the results, Poisson statistics adequately describes the counting experiment for short measuring times. (author) 13 refs.; 4 figs

  8. Backscatter absorption gas imaging systems and light sources therefore

    Kulp, Thomas Jan [Livermore, CA; Kliner, Dahv A. V. [San Ramon, CA; Sommers, Ricky [Oakley, CA; Goers, Uta-Barbara [Campbell, NY; Armstrong, Karla M [Livermore, CA

    2006-12-19

    The location of gases that are not visible to the unaided human eye can be determined using tuned light sources that spectroscopically probe the gases and cameras that can provide images corresponding to the absorption of the gases. The present invention is a light source for a backscatter absorption gas imaging (BAGI) system, and a light source incorporating the light source, that can be used to remotely detect and produce images of "invisible" gases. The inventive light source has a light producing element, an optical amplifier, and an optical parametric oscillator to generate wavelength tunable light in the IR. By using a multi-mode light source and an amplifier that operates using 915 nm pump sources, the power consumption of the light source is reduced to a level that can be operated by batteries for long periods of time. In addition, the light source is tunable over the absorption bands of many hydrocarbons, making it useful for detecting hazardous gases.

  9. Uncertainty in Earthquake Source Imaging Due to Variations in Source Time Function and Earth Structure

    Razafindrakoto, H. N. T.

    2014-03-25

    One way to improve the accuracy and reliability of kinematic earthquake source imaging is to investigate the origin of uncertainty and to minimize their effects. The difficulties in kinematic source inversion arise from the nonlinearity of the problem, nonunique choices in the parameterization, and observational errors. We analyze particularly the uncertainty related to the choice of the source time function (STF) and the variability in Earth structure. We consider a synthetic data set generated from a spontaneous dynamic rupture calculation. Using Bayesian inference, we map the solution space of peak slip rate, rupture time, and rise time to characterize the kinematic rupture in terms of posterior density functions. Our test to investigate the effect of the choice of STF reveals that all three tested STFs (isosceles triangle, regularized Yoffe with acceleration time of 0.1 and 0.3 s) retrieve the patch of high slip and slip rate around the hypocenter. However, the use of an isosceles triangle as STF artificially accelerates the rupture to propagate faster than the target solution. It additionally generates an artificial linear correlation between rupture onset time and rise time. These appear to compensate for the dynamic source effects that are not included in the symmetric triangular STF. The exact rise time for the tested STFs is difficult to resolve due to the small amount of radiated seismic moment in the tail of STF. To highlight the effect of Earth structure variability, we perform inversions including the uncertainty in the wavespeed only, and variability in both wavespeed and layer depth. We find that little difference is noticeable between the resulting rupture model uncertainties from these two parameterizations. Both significantly broaden the posterior densities and cause faster rupture propagation particularly near the hypocenter due to the major velocity change at the depth where the fault is located.

  10. Uncertainty in Earthquake Source Imaging Due to Variations in Source Time Function and Earth Structure

    Razafindrakoto, H. N. T.; Mai, Paul Martin

    2014-01-01

    One way to improve the accuracy and reliability of kinematic earthquake source imaging is to investigate the origin of uncertainty and to minimize their effects. The difficulties in kinematic source inversion arise from the nonlinearity of the problem, nonunique choices in the parameterization, and observational errors. We analyze particularly the uncertainty related to the choice of the source time function (STF) and the variability in Earth structure. We consider a synthetic data set generated from a spontaneous dynamic rupture calculation. Using Bayesian inference, we map the solution space of peak slip rate, rupture time, and rise time to characterize the kinematic rupture in terms of posterior density functions. Our test to investigate the effect of the choice of STF reveals that all three tested STFs (isosceles triangle, regularized Yoffe with acceleration time of 0.1 and 0.3 s) retrieve the patch of high slip and slip rate around the hypocenter. However, the use of an isosceles triangle as STF artificially accelerates the rupture to propagate faster than the target solution. It additionally generates an artificial linear correlation between rupture onset time and rise time. These appear to compensate for the dynamic source effects that are not included in the symmetric triangular STF. The exact rise time for the tested STFs is difficult to resolve due to the small amount of radiated seismic moment in the tail of STF. To highlight the effect of Earth structure variability, we perform inversions including the uncertainty in the wavespeed only, and variability in both wavespeed and layer depth. We find that little difference is noticeable between the resulting rupture model uncertainties from these two parameterizations. Both significantly broaden the posterior densities and cause faster rupture propagation particularly near the hypocenter due to the major velocity change at the depth where the fault is located.

  11. Computed tomography as a source of electron density information for radiation treatment planning

    Skrzynski, Witold; Slusarczyk-Kacprzyk, Wioletta; Bulski, Wojciech; Zielinska-Dabrowska, Sylwia; Wachowicz, Marta; Kukolowicz, Pawel F.

    2010-01-01

    Purpose: to evaluate the performance of computed tomography (CT) systems of various designs as a source of electron density (ρ el ) data for treatment planning of radiation therapy. Material and methods: dependence of CT numbers on relative electron density of tissue-equivalent materials (HU-ρ el relationship) was measured for several general-purpose CT systems (single-slice, multislice, wide-bore multislice), for radiotherapy simulators with a single-slice CT and kV CBCT (cone-beam CT) options, as well as for linear accelerators with kV and MV CBCT systems. Electron density phantoms of four sizes were used. Measurement data were compared with the standard HU-ρ el relationships predefined in two commercial treatment-planning systems (TPS). Results: the HU-ρ el relationships obtained with all of the general-purpose CT scanners operating at voltages close to 120 kV were very similar to each other and close to those predefined in TPS. Some dependency of HU values on tube voltage was observed for bone-equivalent materials. For a given tube voltage, differences in results obtained for different phantoms were larger than those obtained for different CT scanners. For radiotherapy simulators and for kV CBCT systems, the information on ρ el was much less precise because of poor uniformity of images. For MV CBCT, the results were significantly different than for kV systems due to the differing energy spectrum of the beam. Conclusion: the HU-ρ el relationships predefined in TPS can be used for general-purpose CT systems operating at voltages close to 120 kV. For nontypical imaging systems (e.g., CBCT), the relationship can be significantly different and, therefore, it should always be measured and carefully analyzed before using CT data for treatment planning. (orig.)

  12. Image quality improvements using adaptive statistical iterative reconstruction for evaluating chronic myocardial infarction using iodine density images with spectral CT.

    Kishimoto, Junichi; Ohta, Yasutoshi; Kitao, Shinichiro; Watanabe, Tomomi; Ogawa, Toshihide

    2018-04-01

    Single-source dual-energy CT (ssDECT) allows the reconstruction of iodine density images (IDIs) from projection based computing. We hypothesized that adding adaptive statistical iterative reconstruction (ASiR) could improve image quality. The aim of our study was to evaluate the effect and determine the optimal blend percentages of ASiR for IDI of myocardial late iodine enhancement (LIE) in the evaluation of chronic myocardial infarction using ssDECT. A total of 28 patients underwent cardiac LIE using a ssDECT scanner. IDIs between 0 and 100% of ASiR contributions in 10% increments were reconstructed. The signal-to-noise ratio (SNR) of remote myocardia and the contrast-to-noise ratio (CNR) of infarcted myocardia were measured. Transmural extent of infarction was graded using a 5-point scale. The SNR, CNR, and transmural extent were assessed for each ASiR contribution ratio. The transmural extents were compared with MRI as a reference standard. Compared to 0% ASiR, the use of 20-100% ASiR resulted in a reduction of image noise (p ASiR images, reconstruction with 100% ASiR image showed the highest improvement in SNR (229%; p ASiR above 80% showed the highest ratio (73.7%) of accurate transmural extent classification. In conclusion, ASiR intensity of 80-100% in IDIs can improve image quality without changes in signal and maximizes the accuracy of transmural extent in infarcted myocardium.

  13. Electrophysiological Source Imaging: A Noninvasive Window to Brain Dynamics.

    He, Bin; Sohrabpour, Abbas; Brown, Emery; Liu, Zhongming

    2018-06-04

    Brain activity and connectivity are distributed in the three-dimensional space and evolve in time. It is important to image brain dynamics with high spatial and temporal resolution. Electroencephalography (EEG) and magnetoencephalography (MEG) are noninvasive measurements associated with complex neural activations and interactions that encode brain functions. Electrophysiological source imaging estimates the underlying brain electrical sources from EEG and MEG measurements. It offers increasingly improved spatial resolution and intrinsically high temporal resolution for imaging large-scale brain activity and connectivity on a wide range of timescales. Integration of electrophysiological source imaging and functional magnetic resonance imaging could further enhance spatiotemporal resolution and specificity to an extent that is not attainable with either technique alone. We review methodological developments in electrophysiological source imaging over the past three decades and envision its future advancement into a powerful functional neuroimaging technology for basic and clinical neuroscience applications.

  14. Progress toward the development and testing of source reconstruction methods for NIF neutron imaging.

    Loomis, E N; Grim, G P; Wilde, C; Wilson, D C; Morgan, G; Wilke, M; Tregillis, I; Merrill, F; Clark, D; Finch, J; Fittinghoff, D; Bower, D

    2010-10-01

    Development of analysis techniques for neutron imaging at the National Ignition Facility is an important and difficult task for the detailed understanding of high-neutron yield inertial confinement fusion implosions. Once developed, these methods must provide accurate images of the hot and cold fuels so that information about the implosion, such as symmetry and areal density, can be extracted. One method under development involves the numerical inversion of the pinhole image using knowledge of neutron transport through the pinhole aperture from Monte Carlo simulations. In this article we present results of source reconstructions based on simulated images that test the methods effectiveness with regard to pinhole misalignment.

  15. Transport calculations of. gamma. -ray flux density and dose rate about implantable californium-252 sources

    Shapiro, A; Lin, B I [Cincinnati Univ., Ohio (USA). Dept. of Chemical and Nuclear Engineering; Windham, J P; Kereiakes, J G

    1976-07-01

    ..gamma.. flux density and dose rate distributions have been calculated about implantable californium-252 sources for an infinite tissue medium. Point source flux densities as a function of energy and position were obtained from a discrete-ordinates calculation, and the flux densities were multiplied by their corresponding kerma factors and added to obtain point source dose rates. The point dose rates were integrated over the line source to obtain line dose rates. Container attenuation was accounted for by evaluating the point dose rate as a function of platinum thickness. Both primary and secondary flux densities and dose rates are presented. The agreement with an independent Monte Carlo calculation was excellent. The data presented should be useful for the design of new source configurations.

  16. Automated Measurement Of The Density Of Vessels On Whole Slide Images Of Paediatric Brain Tumours

    Christophe Deroulers

    2016-06-01

    Only a few parameters have to be chosen, once and for all samples (e.g., the minimal acceptable size of a blood vessel fragment, which makes the method more robust than assessment by a (panel of human expert(s. The automatic calibration steps enable one to deal with a heterogeneous set of slides (e.g., slight differences in background colour and staining. The method uses only open-source software. It is easy to extend or improve and not tight to a single immunomarker. We applied the method to 129 paediatric brain tumours of 8 different types and 3 locations (posterior fossa, thalamus, hemispheres — 185 samples in total. For each patient, the density of microvessels in the sample is compared to the cerebral blood flow as assessed by preoperative perfusion-weighted-imaging using arterial-spin-labeling. We find a good correlation between microvascular density, MRI data and tumour grading. The microvascular density is broadly distributed among the samples. Visualisation in a web browser is slightly more fluid when images are uploaded in the DeepZoom format rather than as pyramidal TIFF images, but the former consumes roughly 20 times more disk space and needs the transfer of a very large number of files after each modification, which is less tractable.

  17. Silicon micromachining using a high-density plasma source

    McAuley, S.A.; Ashraf, H.; Atabo, L.; Chambers, A.; Hall, S.; Hopkins, J.; Nicholls, G.

    2001-01-01

    Dry etching of Si is critical in satisfying the demands of the micromachining industry. The micro-electro-mechanical systems (MEMS) community requires etches capable of high aspect ratios, vertical profiles, good feature size control and etch uniformity along with high throughput to satisfy production requirements. Surface technology systems' (STS's) high-density inductively coupled plasma (ICP) etch tool enables a wide range of applications to be realized whilst optimizing the above parameters. Components manufactured from Si using an STS ICP include accelerometers and gyroscopes for military, automotive and domestic applications. STS's advanced silicon etch (ASE TM ) has also allowed the first generation of MEMS-based optical switches and attenuators to reach the marketplace. In addition, a specialized application for fabricating the next generation photolithography exposure masks has been optimized for 200 mm diameter wafers, to depths of ∼750 μm. Where the profile is not critical, etch rates of greater than 8 μm min -1 have been realized to replace previous methods such as wet etching. This is also the case for printer applications. Specialized applications that require etching down to pyrex or oxide often result in the loss of feature size control at the interface; this is an industry wide problem. STS have developed a technique to address this. The rapid progression of the industry has led to development of the STS ICP etch tool, as well as the process. (author)

  18. Implementation of 252Cf-source-driven power spectrum density measurement system

    Ren Yong; Wei Biao; Feng Peng; Li Jiansheng; Ye Cenming

    2012-01-01

    The principle of 252 Cf-source-driven power spectrum density measurement method is introduced. A measurement system and platform is realized accordingly, which is a combination of hardware and software, for measuring nuclear parameters. The detection method of neutron pulses based on an ultra-high-speed data acquisition card (three channels, 1 GHz sampling rate, 1 ns synchronization) is described, and the data processing process and the power spectrum density algorithm on PC are designed. This 252 Cf-source-driven power spectrum density measurement system can effectively obtain the nuclear tag parameters of nuclear random processes, such as correlation function and power spectrum density. (authors)

  19. Automated detection and labeling of high-density EEG electrodes from structural MR images

    Marino, Marco; Liu, Quanying; Brem, Silvia; Wenderoth, Nicole; Mantini, Dante

    2016-10-01

    Objective. Accurate knowledge about the positions of electrodes in electroencephalography (EEG) is very important for precise source localizations. Direct detection of electrodes from magnetic resonance (MR) images is particularly interesting, as it is possible to avoid errors of co-registration between electrode and head coordinate systems. In this study, we propose an automated MR-based method for electrode detection and labeling, particularly tailored to high-density montages. Approach. Anatomical MR images were processed to create an electrode-enhanced image in individual space. Image processing included intensity non-uniformity correction, background noise and goggles artifact removal. Next, we defined a search volume around the head where electrode positions were detected. Electrodes were identified as local maxima in the search volume and registered to the Montreal Neurological Institute standard space using an affine transformation. This allowed the matching of the detected points with the specific EEG montage template, as well as their labeling. Matching and labeling were performed by the coherent point drift method. Our method was assessed on 8 MR images collected in subjects wearing a 256-channel EEG net, using the displacement with respect to manually selected electrodes as performance metric. Main results. Average displacement achieved by our method was significantly lower compared to alternative techniques, such as the photogrammetry technique. The maximum displacement was for more than 99% of the electrodes lower than 1 cm, which is typically considered an acceptable upper limit for errors in electrode positioning. Our method showed robustness and reliability, even in suboptimal conditions, such as in the case of net rotation, imprecisely gathered wires, electrode detachment from the head, and MR image ghosting. Significance. We showed that our method provides objective, repeatable and precise estimates of EEG electrode coordinates. We hope our work

  20. Presurgical mapping with magnetic source imaging. Comparisons with intraoperative findings

    Roberts, T.P.L.; Ferrari, P.; Perry, D.; Rowley, H.A.; Berger, M.S.

    2000-01-01

    We compare noninvasive preoperative mapping with magnetic source imaging to intraoperative cortical stimulation mapping. These techniques were directly compared in 17 patients who underwent preoperative and postoperative somatosensory mapping of a total of 22 comparable anatomic sites (digits, face). Our findings are presented in the context of previous studies that used magnetic source imaging and functional magnetic resonance imaging as noninvasive surrogates of intraoperative mapping for the identification of sensorimotor and language-specific brain functional centers in patients with brain tumors. We found that magnetic source imaging results were reasonably concordant with intraoperative mapping findings in over 90% of cases, and that concordance could be defined as 'good' in 77% of cases. Magnetic source imaging therefore provides a viable, if coarse, identification of somatosensory areas and, consequently, can guide and reduce the time taken for intraoperative mapping procedures. (author)

  1. Comparison of source moment tensor recovered by diffraction stacking migration and source time reversal imaging

    Zhang, Q.; Zhang, W.

    2017-12-01

    Diffraction stacking migration is an automatic location methods and widely used in microseismic monitoring of the hydraulic fracturing. It utilizes the stacking of thousands waveform to enhance signal-to-noise ratio of weak events. For surface monitoring, the diffraction stacking method is suffered from polarity reverse among receivers due to radiation pattern of moment source. Joint determination of location and source mechanism has been proposed to overcome the polarity problem but needs significantly increased computational calculations. As an effective method to recover source moment tensor, time reversal imaging based on wave equation can locate microseismic event by using interferometry on the image to extract source position. However, the time reversal imaging is very time consuming compared to the diffraction stacking location because of wave-equation simulation.In this study, we compare the image from diffraction stacking and time reversal imaging to check if the diffraction stacking can obtain similar moment tensor as time reversal imaging. We found that image produced by taking the largest imaging value at each point along time axis does not exhibit the radiation pattern, while with the same level of calculation efficiency, the image produced for each trial origin time can generate radiation pattern similar to time reversal imaging procedure. Thus it is potential to locate the source position by the diffraction stacking method for general moment tensor sources.

  2. Neutral-depletion-induced axially asymmetric density in a helicon source and imparted thrust

    Takahashi, Kazunori; Takao, Yoshinori; Ando, Akira

    2016-02-01

    The high plasma density downstream of the source is observed to be sustained only for a few hundreds of microsecond at the initial phase of the discharge, when pulsing the radiofrequency power of a helicon plasma thruster. Measured relative density of argon neutrals inside the source implies that the neutrals are significantly depleted there. A position giving a maximum plasma density temporally moves to the upstream side of the source due to the neutral depletion and then the exhausted plasma density significantly decreases. The direct thrust measurement demonstrates that the higher thrust-to-power ratio is obtained by using only the initial phase of the high density plasma, compared with the steady-state operation.

  3. Optical Imaging of Ionizing Radiation from Clinical Sources.

    Shaffer, Travis M; Drain, Charles Michael; Grimm, Jan

    2016-11-01

    Nuclear medicine uses ionizing radiation for both in vivo diagnosis and therapy. Ionizing radiation comes from a variety of sources, including x-rays, beam therapy, brachytherapy, and various injected radionuclides. Although PET and SPECT remain clinical mainstays, optical readouts of ionizing radiation offer numerous benefits and complement these standard techniques. Furthermore, for ionizing radiation sources that cannot be imaged using these standard techniques, optical imaging offers a unique imaging alternative. This article reviews optical imaging of both radionuclide- and beam-based ionizing radiation from high-energy photons and charged particles through mechanisms including radioluminescence, Cerenkov luminescence, and scintillation. Therapeutically, these visible photons have been combined with photodynamic therapeutic agents preclinically for increasing therapeutic response at depths difficult to reach with external light sources. Last, new microscopy methods that allow single-cell optical imaging of radionuclides are reviewed. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  4. Virtual ultrasound sources in high-resolution ultrasound imaging

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2002-01-01

    beamforming procedure for 3D ultrasound imaging. The position of the virtual source, and the created waveform are investigated with simulation, and with pulse-echo measurements. There is good agreement between the estimated wavefront and the theoretically tted one. Several examples of the use of virtual...... source elements are considered. Using SAF on data acquired for a conventional linear array imaging improves the penetration depth for the particular imaging situation from 80 to 110 mm. The independent use of virtual source elements in the elevation plane decreases the respective size of the point spread...

  5. High Current, High Density Arc Plasma as a New Source for WiPAL

    Waleffe, Roger; Endrizzi, Doug; Myers, Rachel; Wallace, John; Clark, Mike; Forest, Cary; WiPAL Team

    2016-10-01

    The Wisconsin Plasma Astrophysics Lab (WiPAL) has installed a new array of nineteen plasma sources (plasma guns) on its 3 m diameter, spherical vacuum vessel. Each gun is a cylindrical, molybdenum, washer-stabilized, arc plasma source. During discharge, the guns are maintained at 1.2 kA across 100 V for 10 ms by the gun power supply establishing a high density plasma. Each plasma source is fired independently allowing for adjustable plasma parameters, with densities varying between 1018 -1019 m-3 and electron temperatures of 5-15 eV. Measurements were characterized using a 16 tip Langmuir probe. The plasma source will be used as a background plasma for the magnetized coaxial plasma gun (MCPG), the Terrestrial Reconnection Experiment (TREX), and as the plasma source for a magnetic mirror experiment. Temperature, density, and confinement results will be presented. This work is supported by the DoE and the NSF.

  6. Future prospects of imaging at spallation neutron sources

    Strobl, M.

    2009-01-01

    The advent of state-of-the-art spallation neutron sources is a major step forward in efficient neutron production for most neutron scattering techniques. Although they provide lower time-averaged neutron flux than high flux reactor sources, advantage for different instrumental techniques can be derived from the pulsed time structure of the available flux, which can be translated into energy, respectively, wavelength resolution. Conventional neutron imaging on the other hand relies on an intense continuous beam flux and hence falls short in profiting from the new development. Nevertheless, some recently developed novel imaging techniques require and some can benefit from energy resolution. The impact of the emerging spallation sources on different imaging techniques has been investigated, ways to benefit will be identified (where possible) and prospects of future imaging instruments and possible options and layouts at a spallation neutron source will be discussed and outlined.

  7. An evolution of image source camera attribution approaches.

    Jahanirad, Mehdi; Wahab, Ainuddin Wahid Abdul; Anuar, Nor Badrul

    2016-05-01

    Camera attribution plays an important role in digital image forensics by providing the evidence and distinguishing characteristics of the origin of the digital image. It allows the forensic analyser to find the possible source camera which captured the image under investigation. However, in real-world applications, these approaches have faced many challenges due to the large set of multimedia data publicly available through photo sharing and social network sites, captured with uncontrolled conditions and undergone variety of hardware and software post-processing operations. Moreover, the legal system only accepts the forensic analysis of the digital image evidence if the applied camera attribution techniques are unbiased, reliable, nondestructive and widely accepted by the experts in the field. The aim of this paper is to investigate the evolutionary trend of image source camera attribution approaches from fundamental to practice, in particular, with the application of image processing and data mining techniques. Extracting implicit knowledge from images using intrinsic image artifacts for source camera attribution requires a structured image mining process. In this paper, we attempt to provide an introductory tutorial on the image processing pipeline, to determine the general classification of the features corresponding to different components for source camera attribution. The article also reviews techniques of the source camera attribution more comprehensively in the domain of the image forensics in conjunction with the presentation of classifying ongoing developments within the specified area. The classification of the existing source camera attribution approaches is presented based on the specific parameters, such as colour image processing pipeline, hardware- and software-related artifacts and the methods to extract such artifacts. The more recent source camera attribution approaches, which have not yet gained sufficient attention among image forensics

  8. HIGH-RESOLUTION IMAGING OF THE ATLBS REGIONS: THE RADIO SOURCE COUNTS

    Thorat, K.; Subrahmanyan, R.; Saripalli, L.; Ekers, R. D., E-mail: kshitij@rri.res.in [Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560080 (India)

    2013-01-01

    The Australia Telescope Low-brightness Survey (ATLBS) regions have been mosaic imaged at a radio frequency of 1.4 GHz with 6'' angular resolution and 72 {mu}Jy beam{sup -1} rms noise. The images (centered at R.A. 00{sup h}35{sup m}00{sup s}, decl. -67 Degree-Sign 00'00'' and R.A. 00{sup h}59{sup m}17{sup s}, decl. -67 Degree-Sign 00'00'', J2000 epoch) cover 8.42 deg{sup 2} sky area and have no artifacts or imaging errors above the image thermal noise. Multi-resolution radio and optical r-band images (made using the 4 m CTIO Blanco telescope) were used to recognize multi-component sources and prepare a source list; the detection threshold was 0.38 mJy in a low-resolution radio image made with beam FWHM of 50''. Radio source counts in the flux density range 0.4-8.7 mJy are estimated, with corrections applied for noise bias, effective area correction, and resolution bias. The resolution bias is mitigated using low-resolution radio images, while effects of source confusion are removed by using high-resolution images for identifying blended sources. Below 1 mJy the ATLBS counts are systematically lower than the previous estimates. Showing no evidence for an upturn down to 0.4 mJy, they do not require any changes in the radio source population down to the limit of the survey. The work suggests that automated image analysis for counts may be dependent on the ability of the imaging to reproduce connecting emission with low surface brightness and on the ability of the algorithm to recognize sources, which may require that source finding algorithms effectively work with multi-resolution and multi-wavelength data. The work underscores the importance of using source lists-as opposed to component lists-and correcting for the noise bias in order to precisely estimate counts close to the image noise and determine the upturn at sub-mJy flux density.

  9. Accuracy of lung nodule density on HRCT: analysis by PSF-based image simulation.

    Ohno, Ken; Ohkubo, Masaki; Marasinghe, Janaka C; Murao, Kohei; Matsumoto, Toru; Wada, Shinichi

    2012-11-08

    A computed tomography (CT) image simulation technique based on the point spread function (PSF) was applied to analyze the accuracy of CT-based clinical evaluations of lung nodule density. The PSF of the CT system was measured and used to perform the lung nodule image simulation. Then, the simulated image was resampled at intervals equal to the pixel size and the slice interval found in clinical high-resolution CT (HRCT) images. On those images, the nodule density was measured by placing a region of interest (ROI) commonly used for routine clinical practice, and comparing the measured value with the true value (a known density of object function used in the image simulation). It was quantitatively determined that the measured nodule density depended on the nodule diameter and the image reconstruction parameters (kernel and slice thickness). In addition, the measured density fluctuated, depending on the offset between the nodule center and the image voxel center. This fluctuation was reduced by decreasing the slice interval (i.e., with the use of overlapping reconstruction), leading to a stable density evaluation. Our proposed method of PSF-based image simulation accompanied with resampling enables a quantitative analysis of the accuracy of CT-based evaluations of lung nodule density. These results could potentially reveal clinical misreadings in diagnosis, and lead to more accurate and precise density evaluations. They would also be of value for determining the optimum scan and reconstruction parameters, such as image reconstruction kernels and slice thicknesses/intervals.

  10. Measuring the Plasma Density of a Ferroelectric Plasma Source in an Expanding Plasma

    Dunaevsky, A.; Fisch, N.J.

    2003-01-01

    The initial density and electron temperature at the surface of a ferroelectric plasma source were deduced from floating probe measurements in an expanding plasma. The method exploits negative charging of the floating probe capacitance by fast flows before the expanding plasma reaches the probe. The temporal profiles of the plasma density can be obtained from the voltage traces of the discharge of the charged probe capacitance by the ion current from the expanding plasma. The temporal profiles of the plasma density, at two different distances from the surface of the ferroelectric plasma source, could be further fitted by using the density profiles for the expanding plasma. This gives the initial values of the plasma density and electron temperature at the surface. The method could be useful for any pulsed discharge, which is accompanied by considerable electromagnetic noise, if the initial plasma parameters might be deduced from measurements in expanding plasma

  11. Source position error influence on industry CT image quality

    Cong Peng; Li Zhipeng; Wu Haifeng

    2004-01-01

    Based on the emulational exercise, the influence of source position error on industry CT (ICT) image quality was studied and the valuable parameters were obtained for the design of ICT. The vivid container CT image was also acquired from the CT testing system. (authors)

  12. Sparse Source EEG Imaging with the Variational Garrote

    Hansen, Sofie Therese; Stahlhut, Carsten; Hansen, Lars Kai

    2013-01-01

    EEG imaging, the estimation of the cortical source distribution from scalp electrode measurements, poses an extremely ill-posed inverse problem. Recent work by Delorme et al. (2012) supports the hypothesis that distributed source solutions are sparse. We show that direct search for sparse solutions...

  13. New neutron imaging using pulsed sources. Characteristics of a pulsed neutron source and principle of pulsed neutron imaging

    Kiyanagi, Yoshiaki

    2012-01-01

    Neutron beam is one of important tools to obtain the transmission image of an object. Until now, steady state neutron sources such as reactors are mainly used for this imaging purpose. Recently, it has been demonstrated that pulsed neutron imaging based on accelerator neutron sources can provide a real-space distribution of physical information of materials such as crystallographic structure, element, temperature, hydrogen bound state, magnetic field and so on, by analyzing wavelength dependent transmission spectrum, which information cannot be observed or difficult to obtain with a traditional imaging method using steady state neutrons. Here, characteristics of the pulsed neutron source and principle of the pulsed neutron imaging are explained as a basic concept of the new method. (author)

  14. Limits on the space density of gamma-ray burst sources

    Epstein, R.I.

    1985-01-01

    Gamma-ray burst spectra which extend to several MeV without significant steepening indicate that there is negligible degradation due to two-photon pair production. The inferred low rate of photon-photon reactions is used to give upper limits to the distances to the sources and to the intensity of the radiation from the sources. These limits are calculated under the assumptions that the bursters are neutron stars which emit uncollimated gamma rays. The principal results are that the space density of the gamma-ray burst sources exceeds approx.10 -6 pc -3 if the entire surface of the neutron star radiates and exceeds approx.10 -3 pc -3 if only a small cap or thin strip in the stellar surface radiates. In the former case the density of gamma-ray bursters is approx.1% of the inferred density of extinct pulsars, and in the latter case the mean mass density of burster sources is a few percent of the density of unidentified dark matter in the solar neighborhood. In both cases the X-ray intensity of the sources is far below the Rayleigh-Jeans limit, and the total flux is at most comparable to the Eddington limit. This implies that low-energy self-absorption near 10 keV is entirely negligible and that radiation-driven explosions are just barely possible

  15. Density-based retrieval from high-similarity image databases

    Hansen, Michael Edberg; Carstensen, Jens Michael

    2004-01-01

    Many image classification problems can fruitfully be thought of as image retrieval in a "high similarity image database" (HSID) characterized by being tuned towards a specific application and having a high degree of visual similarity between entries that should be distinguished. We introduce a me...

  16. Gadgetron: An Open Source Framework for Medical Image Reconstruction

    Hansen, Michael Schacht; Sørensen, Thomas Sangild

    2013-01-01

    This work presents a new open source framework for medical image reconstruction called the “Gadgetron.” The framework implements a flexible system for creating streaming data processing pipelines where data pass through a series of modules or “Gadgets” from raw data to reconstructed images...... with a set of dedicated toolboxes in shared libraries for medical image reconstruction. This includes generic toolboxes for data-parallel (e.g., GPU-based) execution of compute-intensive components. The basic framework architecture is independent of medical imaging modality, but this article focuses on its...

  17. Electron density and temperature in NIO1 RF source operated in oxygen and argon

    Barbisan, M.; Zaniol, B.; Cavenago, M.; Pasqualotto, R.; Serianni, G.; Zanini, M.

    2017-08-01

    The NIO1 experiment, built and operated at Consorzio RFX, hosts an RF negative ion source, from which it is possible to produce a beam of maximum 130 mA in H- ions, accelerated up to 60 kV. For the preliminary tests of the extraction system the source has been operated in oxygen, whose high electronegativity allows to reach useful levels of extracted beam current. The efficiency of negative ions extraction is strongly influenced by the electron density and temperature close to the Plasma Grid, i.e. the grid of the acceleration system which faces the source. To support the tests, these parameters have been measured by means of the Optical Emission Spectroscopy diagnostic. This technique has involved the use of an oxygen-argon mixture to produce the plasma in the source. The intensities of specific Ar I and Ar II lines have been measured along lines of sight close to the Plasma Grid, and have been interpreted with the ADAS package to get the desired information. This work will describe the diagnostic hardware, the analysis method and the measured values of electron density and temperature, as function of the main source parameters (RF power, pressure, bias voltage and magnetic filter field). The main results show that not only electron density but also electron temperature increase with RF power; both decrease with increasing magnetic filter field. Variations of source pressure and plasma grid bias voltage appear to affect only electron temperature and electron density, respectively.

  18. Source-Free Exchange-Correlation Magnetic Fields in Density Functional Theory.

    Sharma, S; Gross, E K U; Sanna, A; Dewhurst, J K

    2018-03-13

    Spin-dependent exchange-correlation energy functionals in use today depend on the charge density and the magnetization density: E xc [ρ, m]. However, it is also correct to define the functional in terms of the curl of m for physical external fields: E xc [ρ,∇ × m]. The exchange-correlation magnetic field, B xc , then becomes source-free. We study this variation of the theory by uniquely removing the source term from local and generalized gradient approximations to the functional. By doing so, the total Kohn-Sham moments are improved for a wide range of materials for both functionals. Significantly, the moments for the pnictides are now in good agreement with experiment. This source-free method is simple to implement in all existing density functional theory codes.

  19. Influential sources affecting Bangkok adolescent body image perceptions.

    Thianthai, Chulanee

    2006-01-01

    The study of body image-related problems in non-Western countries is still very limited. Thus, this study aims to identify the main influential sources and show how they affect the body image perceptions of Bangkok adolescents. The researcher recruited 400 Thai male and female adolescents in Bangkok, attending high school to freshmen level, ranging from 16-19 years, to participate in this study. Survey questionnaires were distributed to every student and follow-up interviews conducted with 40 students. The findings showed that there are eight main influential sources respectively ranked from the most influential to the least influential: magazines, television, peer group, familial, fashion trend, the opposite gender, self-realization and health knowledge. Similar to those studies conducted in Western countries, more than half of the total percentage was the influence of mass media and peer groups. Bangkok adolescents also internalized Western ideal beauty through these mass media channels. Alike studies conducted in the West, there was similarities in the process of how these influential sources affect Bangkok adolescent body image perception, with the exception of familial source. In conclusion, taking the approach of identifying the main influential sources and understanding how they affect adolescent body image perceptions can help prevent adolescents from having unhealthy views and taking risky measures toward their bodies. More studies conducted in non-Western countries are needed in order to build a cultural sensitive program, catered to the body image problems occurring in adolescents within that particular society.

  20. Impact of neutral density fluctuations on gas puff imaging diagnostics

    Wersal, C.; Ricci, P.

    2017-11-01

    A three-dimensional turbulence simulation of the SOL and edge regions of a toroidally limited tokamak is carried out. The simulation couples self-consistently the drift-reduced two-fluid Braginskii equations to a kinetic equation for neutral atoms. A diagnostic neutral gas puff on the low-field side midplane is included and the impact of neutral density fluctuations on D_α light emission investigated. We find that neutral density fluctuations affect the D_α emission. In particular, at a radial distance from the gas puff smaller than the neutral mean free path, neutral density fluctuations are anti-correlated with plasma density, electron temperature, and D_α fluctuations. It follows that the neutral fluctuations reduce the D_α emission in most of the observed region and, therefore, have to be taken into account when interpreting the amplitude of the D_α emission. On the other hand, higher order statistical moments (skewness, kurtosis) and turbulence characteristics (such as correlation length, or the autocorrelation time) are not significantly affected by the neutral fluctuations. At distances from the gas puff larger than the neutral mean free path, a non-local shadowing effect influences the neutral density fluctuations. There, the D_α fluctuations are correlated with the neutral density fluctuations, and the high-order statistical moments and measurements of other turbulence properties are strongly affected by the neutral density fluctuations.

  1. The effects of variability on the number-flux-density relationship for radio sources

    Schuch, N.J.

    1981-01-01

    It has been known for some time that the number-flux-density relationship for radio sources requires a population of sources whose properties evolve with cosmological epoch, at least in models where the redshifts are all taken to be cosmological. In particular, the surveys made at metre wavelengths show, for bright sources, a slope of the log N -log S curve which is steeper than the value -1.5 expected in a static, non-evolving Euclidean universe. Here, N is the number of radio sources brighter than flux density S. Expansion without evolution in conventional geometrical models predicts slopes flatter than -1.5. If the radio survey is carried out at higher frequencies (typically 2.7 or 5 GHz - 11 or 6 cm wavelength), the slope of the log N -log S curve is steeper than -1.5 but not so steep as the slopes found for the low-frequency surveys. Many of the sources found in high-frequency surveys have radio spectra with relatively higher flux-densities in the centimetre range; these sources are frequently variable at high frequencies, with time-scales from a month or two upwards. Some possible effects of the variations on the observed counts of radio sources are considered. (author)

  2. The VTTVIS line imaging spectrometer - principles, error sources, and calibration

    Jørgensen, R.N.

    2002-01-01

    work describing the basic principles, potential error sources, and/or adjustment and calibration procedures. This report fulfils the need for such documentationwith special focus on the system at KVL. The PGP based system has several severe error sources, which should be removed prior any analysis......Hyperspectral imaging with a spatial resolution of a few mm2 has proved to have a great potential within crop and weed classification and also within nutrient diagnostics. A commonly used hyperspectral imaging system is based on the Prism-Grating-Prism(PGP) principles produced by Specim Ltd...... in off-axis transmission efficiencies, diffractionefficiencies, and image distortion have a significant impact on the instrument performance. Procedures removing or minimising these systematic error sources are developed and described for the system build at KVL but can be generalised to other PGP...

  3. PySE: Python Source Extractor for radio astronomical images

    Spreeuw, Hanno; Swinbank, John; Molenaar, Gijs; Staley, Tim; Rol, Evert; Sanders, John; Scheers, Bart; Kuiack, Mark

    2018-05-01

    PySE finds and measures sources in radio telescope images. It is run with several options, such as the detection threshold (a multiple of the local noise), grid size, and the forced clean beam fit, followed by a list of input image files in standard FITS or CASA format. From these, PySe provides a list of found sources; information such as the calculated background image, source list in different formats (e.g. text, region files importable in DS9), and other data may be saved. PySe can be integrated into a pipeline; it was originally written as part of the LOFAR Transient Detection Pipeline (TraP, ascl:1412.011).

  4. Flux density measurements of radio sources at 2.14 millimeter wavelength

    Cogdell, J.R.; Davis, J.H.; Ulrich, B.T.; Wills, B.J.

    1975-01-01

    Flux densities of galactic and extragalactic sources, and planetary temperatures, have been measured at 2.14 mm wavelength (140 GHz). Results are presented for OJ 287; the galactic sources DR 21, W3, and Orion A; the extragalactic sources PKS 0106plus-or-minus01, 3C 84, 3C 120, BL Lac, 3C 216, 3C 273, 3C 279, and NGC 4151; and the Sun, Venus, Mars, and Jupiter. Also presented is the first measurement of the 2.14-mm temperature of Uranus. The spectra of some of these sources are discussed. The flux density scale was calibrated absolutely. The measurements were made with a new continuum receiver on the 4.88-m radio telescope of The University of Texas

  5. PySE: Software for extracting sources from radio images

    Carbone, D.; Garsden, H.; Spreeuw, H.; Swinbank, J. D.; van der Horst, A. J.; Rowlinson, A.; Broderick, J. W.; Rol, E.; Law, C.; Molenaar, G.; Wijers, R. A. M. J.

    2018-04-01

    PySE is a Python software package for finding and measuring sources in radio telescope images. The software was designed to detect sources in the LOFAR telescope images, but can be used with images from other radio telescopes as well. We introduce the LOFAR Telescope, the context within which PySE was developed, the design of PySE, and describe how it is used. Detailed experiments on the validation and testing of PySE are then presented, along with results of performance testing. We discuss some of the current issues with the algorithms implemented in PySE and their interaction with LOFAR images, concluding with the current status of PySE and its future development.

  6. Photoacoustic imaging driven by an interstitial irradiation source

    Trevor Mitcham

    2015-06-01

    Full Text Available Photoacoustic (PA imaging has shown tremendous promise in providing valuable diagnostic and therapy-monitoring information in select clinical procedures. Many of these pursued applications, however, have been relatively superficial due to difficulties with delivering light deep into tissue. To address this limitation, this work investigates generating a PA image using an interstitial irradiation source with a clinical ultrasound (US system, which was shown to yield improved PA signal quality at distances beyond 13 mm and to provide improved spectral fidelity. Additionally, interstitially driven multi-wavelength PA imaging was able to provide accurate spectra of gold nanoshells and deoxyhemoglobin in excised prostate and liver tissue, respectively, and allowed for clear visualization of a wire at 7 cm in excised liver. This work demonstrates the potential of using a local irradiation source to extend the depth capabilities of future PA imaging techniques for minimally invasive interventional radiology procedures.

  7. Intensity correlation imaging with sunlight-like source

    Wang, Wentao; Tang, Zhiguo; Zheng, Huaibin; Chen, Hui; Yuan, Yuan; Liu, Jinbin; Liu, Yanyan; Xu, Zhuo

    2018-05-01

    We show a method of intensity correlation imaging of targets illuminated by a sunlight-like source both theoretically and experimentally. With a Faraday anomalous dispersion optical filter (FADOF), we have modulated the coherence time of a thermal source up to 0.167 ns. And we carried out measurements of temporal and spatial correlations, respectively, with an intensity interferometer setup. By skillfully using the even Fourier fitting on the very sparse sampling data, the images of targets are successfully reconstructed from the low signal-noise-ratio(SNR) interference pattern by applying an iterative phase retrieval algorithm. The resulting imaging quality is as well as the one obtained by the theoretical fitting. The realization of such a case will bring this technique closer to geostationary satellite imaging illuminated by sunlight.

  8. EEG current source density and the phenomenology of the default network.

    Cannon, Rex L; Baldwin, Debora R

    2012-10-01

    In recent years, there has been an increasing line of research dedicated to the investigation of the default mode network (DMN) of the brain and resting state networks. However, the mental activity of the DMN has not been rigorously assessed to date. The specific aims of the current study were 2-fold: First, we sought to determine whether the current source density (CSD) levels in the DMN would correspond to other neuroimaging techniques. Second, we sought to understand the subjective mental activity of the DMN during baseline recordings. This study was conducted with 63 nonclinical participants, 34 female and 29 males with a mean age of 19.2 years (standard deviation = 2.0). The participants were recorded in 8 conditions. First, 4-minute eyes-closed baseline (ECB) and eyes-opened baseline (EOB) were obtained. The participants then completed 3 assessment instruments and 3 image conditions while the electroencephalography (EEG) was continuously recorded. Participants completed subjective reports for baselines and image conditions. These were rated by 3 independent raters and compared for reliability using a random effects model with an absolute agreement definition. The mean CSD between all conditions differed significantly, in many but not all regions of interest in the DMN. Interestingly, as suggested by other studies, the DMN appears preferential to self-relevant, self-specific, or self-perceptive processes. The reliability analyses show α for interrater agreement for ECB at .95 and EOB at .96. The subjective reports obtained from the participants regarding the mental activities employed during baseline recordings correspond to attentional and self-regulatory processes, which may also implicate the resting state or DMN as playing a direct role in the maintenance of a complex behavior (eg, being still, attending, and self-regulating). Thus, attention and self-regulation constitute the phenomenology of the resting state (DMN) in this study. The results also

  9. Quantum image pseudocolor coding based on the density-stratified method

    Jiang, Nan; Wu, Wenya; Wang, Luo; Zhao, Na

    2015-05-01

    Pseudocolor processing is a branch of image enhancement. It dyes grayscale images to color images to make the images more beautiful or to highlight some parts on the images. This paper proposes a quantum image pseudocolor coding scheme based on the density-stratified method which defines a colormap and changes the density value from gray to color parallel according to the colormap. Firstly, two data structures: quantum image GQIR and quantum colormap QCR are reviewed or proposed. Then, the quantum density-stratified algorithm is presented. Based on them, the quantum realization in the form of circuits is given. The main advantages of the quantum version for pseudocolor processing over the classical approach are that it needs less memory and can speed up the computation. Two kinds of examples help us to describe the scheme further. Finally, the future work are analyzed.

  10. Dose performance and image quality: Dual source CT versus single source CT in cardiac CT angiography

    Wang Min; Qi Hengtao; Wang Ximing; Wang Tao; Chen, Jiu-Hong; Liu Cheng

    2009-01-01

    Objective: To evaluate dose performance and image quality of 64-slice dual source CT (DSCT) in comparison to 64-slice single source CT (SSCT) in cardiac CT angiography (CTA). Methods: 100 patients examined by DSCT and 60 patients scanned by SSCT were included in this study. Objective indices such as image noise, contrast-to-noise ratio and signal-to-noise ratio were analyzed. Subjective image quality was assessed by two cardiovascular radiologists in consensus using a four-point scale (1 = excellent to 4 = not acceptable). Estimation of effective dose was performed on the basis of dose length product (DLP). Results: At low heart rates ( 0.05), but, at high heart rates (>70 bpm), DSCT provided robust image quality (P 70 bpm), DSCT is able to provide robust diagnostic image quality at doses far below that of SSCT.

  11. Determining the temperature and density distribution from a Z-pinch radiation source

    Matuska, W.; Lee, H.

    1997-01-01

    High temperature radiation sources exceeding one hundred eV can be produced via z-pinches using currently available pulsed power. The usual approach to compare the z-pinch simulation and experimental data is to convert the radiation output at the source, whose temperature and density distributions are computed from the 2-D MHD code, into simulated data such as a spectrometer reading. This conversion process involves a radiation transfer calculation through the axially symmetric source, assuming local thermodynamic equilibrium (LTE), and folding the radiation that reaches the detector with the frequency-dependent response function. In this paper the authors propose a different approach by which they can determine the temperature and density distributions of the radiation source directly from the spatially resolved spectral data. This unfolding process is reliable and unambiguous for the ideal case where LTE holds and the source is axially symmetric. In reality, imperfect LTE and axial symmetry will introduce inaccuracies into the unfolded distributions. The authors use a parameter optimization routine to find the temperature and density distributions that best fit the data. They know from their past experience that the radiation source resulting from the implosion of a thin foil does not exhibit good axial symmetry. However, recent experiments carried out at Sandia National Laboratory using multiple wire arrays were very promising to achieve reasonably good symmetry. For these experiments the method will provide a valuable diagnostic tool

  12. Incorporating priors for EEG source imaging and connectivity analysis

    Xu eLei

    2015-08-01

    Full Text Available Electroencephalography source imaging (ESI is a useful technique to localize the generators from a given scalp electric measurement and to investigate the temporal dynamics of the large-scale neural circuits. By introducing reasonable priors from other modalities, ESI reveals the most probable sources and communication structures at every moment in time. Here, we review the available priors from such techniques as magnetic resonance imaging (MRI, functional MRI (fMRI, and positron emission tomography (PET. The modality's specific contribution is analyzed from the perspective of source reconstruction. For spatial priors, such as EEG-correlated fMRI, temporally coherent networks and resting-state fMRI are systematically introduced in the ESI. Moreover, the fiber tracking (diffusion tensor imaging, DTI and neuro-stimulation techniques (transcranial magnetic stimulation, TMS are also introduced as the potential priors, which can help to draw inferences about the neuroelectric connectivity in the source space. We conclude that combining EEG source imaging with other complementary modalities is a promising approach towards the study of brain networks in cognitive and clinical neurosciences.

  13. The optimal algorithm for Multi-source RS image fusion.

    Fu, Wei; Huang, Shui-Guang; Li, Zeng-Shun; Shen, Hao; Li, Jun-Shuai; Wang, Peng-Yuan

    2016-01-01

    In order to solve the issue which the fusion rules cannot be self-adaptively adjusted by using available fusion methods according to the subsequent processing requirements of Remote Sensing (RS) image, this paper puts forward GSDA (genetic-iterative self-organizing data analysis algorithm) by integrating the merit of genetic arithmetic together with the advantage of iterative self-organizing data analysis algorithm for multi-source RS image fusion. The proposed algorithm considers the wavelet transform of the translation invariance as the model operator, also regards the contrast pyramid conversion as the observed operator. The algorithm then designs the objective function by taking use of the weighted sum of evaluation indices, and optimizes the objective function by employing GSDA so as to get a higher resolution of RS image. As discussed above, the bullet points of the text are summarized as follows.•The contribution proposes the iterative self-organizing data analysis algorithm for multi-source RS image fusion.•This article presents GSDA algorithm for the self-adaptively adjustment of the fusion rules.•This text comes up with the model operator and the observed operator as the fusion scheme of RS image based on GSDA. The proposed algorithm opens up a novel algorithmic pathway for multi-source RS image fusion by means of GSDA.

  14. Low-emittance uniform density Cs+ sources for heavy ion fusion accelerators studies

    Eylon, S.; Henestroza, E.; Garvey, T.; Johnson, R.; Chupp, W.

    1991-04-01

    Low-emittance (high-brightness) Cs + thermionic sources were developed for the heavy ion induction linac experiment MBE-4 at LBL. The MBE-4 linac accelerates four 10 mA beams from 200 ke V to 900 ke V while amplifying the current up to a factor of nine. Recent studies of the transverse beam dynamics suggested that characteristics of the injector geometry were contributing to the normalized transverse emissions growth. Phase-space and current density distribution measurements of the beam extracted from the injector revealed overfocusing of the outermost rays causing a hollow density profile. We shall report on the performance of a 5 mA scraped beam source (which eliminates the outermost beam rays in the diode) and on the design of an improved 10 mA source. The new source is based on EGUN calculations which indicated that a beam with good emissions and uniform current density could be obtained by modifying the cathode Pierce electrodes and using a spherical emitting surface. The measurements of the beam current density profile on a test stand were found to be in agreement with the numerical simulations. 3 refs., 6 figs

  15. Ultrasound imaging for quantitative evaluation of magnetic density separation

    Sanaee, S.A.

    2013-01-01

    This thesis is dedicated to an investigation of the potential and technological possibilities of an inline ultrasound system as a quality control system for wet recycling of solid waste. The main targeted recycling technology is magnetic density separation (MDS), a novel technique that was

  16. Software Toolbox for Low-Frequency Conductivity and Current Density Imaging Using MRI.

    Sajib, Saurav Z K; Katoch, Nitish; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2017-11-01

    Low-frequency conductivity and current density imaging using MRI includes magnetic resonance electrical impedance tomography (MREIT), diffusion tensor MREIT (DT-MREIT), conductivity tensor imaging (CTI), and magnetic resonance current density imaging (MRCDI). MRCDI and MREIT provide current density and isotropic conductivity images, respectively, using current-injection phase MRI techniques. DT-MREIT produces anisotropic conductivity tensor images by incorporating diffusion weighted MRI into MREIT. These current-injection techniques are finding clinical applications in diagnostic imaging and also in transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), and electroporation where treatment currents can function as imaging currents. To avoid adverse effects of nerve and muscle stimulations due to injected currents, conductivity tensor imaging (CTI) utilizes B1 mapping and multi-b diffusion weighted MRI to produce low-frequency anisotropic conductivity tensor images without injecting current. This paper describes numerical implementations of several key mathematical functions for conductivity and current density image reconstructions in MRCDI, MREIT, DT-MREIT, and CTI. To facilitate experimental studies of clinical applications, we developed a software toolbox for these low-frequency conductivity and current density imaging methods. This MR-based conductivity imaging (MRCI) toolbox includes 11 toolbox functions which can be used in the MATLAB environment. The MRCI toolbox is available at http://iirc.khu.ac.kr/software.html . Its functions were tested by using several experimental datasets, which are provided together with the toolbox. Users of the toolbox can focus on experimental designs and interpretations of reconstructed images instead of developing their own image reconstruction softwares. We expect more toolbox functions to be added from future research outcomes. Low-frequency conductivity and current density imaging using MRI includes

  17. Pulsed x-ray imaging of high-density objects using a ten picosecond high-intensity laser driver

    Rusby, D. R.; Brenner, C. M.; Armstrong, C.; Wilson, L. A.; Clarke, R.; Alejo, A.; Ahmed, H.; Butler, N. M. H.; Haddock, D.; Higginson, A.; McClymont, A.; Mirfayzi, S. R.; Murphy, C.; Notley, M.; Oliver, P.; Allott, R.; Hernandez-Gomez, C.; Kar, S.; McKenna, P.; Neely, D.

    2016-10-01

    Point-like sources of X-rays that are pulsed (sub nanosecond), high energy (up to several MeV) and bright are very promising for industrial and security applications where imaging through large and dense objects is required. Highly penetrating X-rays can be produced by electrons that have been accelerated by a high intensity laser pulse incident onto a thin solid target. We have used a pulse length of 10ps to accelerate electrons to create a bright x-ray source. The bremsstrahlung temperature was measured for a laser intensity from 8.5-12×1018 W/cm2. These x-rays have sequentially been used to image high density materials using image plate and a pixelated scintillator system.

  18. Improvement of density resolution in short-pulse hard x-ray radiographic imaging using detector stacks

    Borm, B.; Gärtner, F.; Khaghani, D. [GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany); Johann Wolfgang Goethe-Universität, Frankfurt am Main (Germany); Neumayer, P. [GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany)

    2016-09-15

    We demonstrate that stacking several imaging plates (IPs) constitutes an easy method to increase hard x-ray detection efficiency. Used to record x-ray radiographic images produced by an intense-laser driven hard x-ray backlighter source, the IP stacks resulted in a significant improvement of the radiograph density resolution. We attribute this to the higher quantum efficiency of the combined detectors, leading to a reduced photon noise. Electron-photon transport simulations of the interaction processes in the detector reproduce the observed contrast improvement. Increasing the detection efficiency to enhance radiographic imaging capabilities is equally effective as increasing the x-ray source yield, e.g., by a larger drive laser energy.

  19. Detecting Large-Scale Brain Networks Using EEG: Impact of Electrode Density, Head Modeling and Source Localization

    Liu, Quanying; Ganzetti, Marco; Wenderoth, Nicole; Mantini, Dante

    2018-01-01

    Resting state networks (RSNs) in the human brain were recently detected using high-density electroencephalography (hdEEG). This was done by using an advanced analysis workflow to estimate neural signals in the cortex and to assess functional connectivity (FC) between distant cortical regions. FC analyses were conducted either using temporal (tICA) or spatial independent component analysis (sICA). Notably, EEG-RSNs obtained with sICA were very similar to RSNs retrieved with sICA from functional magnetic resonance imaging data. It still remains to be clarified, however, what technological aspects of hdEEG acquisition and analysis primarily influence this correspondence. Here we examined to what extent the detection of EEG-RSN maps by sICA depends on the electrode density, the accuracy of the head model, and the source localization algorithm employed. Our analyses revealed that the collection of EEG data using a high-density montage is crucial for RSN detection by sICA, but also the use of appropriate methods for head modeling and source localization have a substantial effect on RSN reconstruction. Overall, our results confirm the potential of hdEEG for mapping the functional architecture of the human brain, and highlight at the same time the interplay between acquisition technology and innovative solutions in data analysis. PMID:29551969

  20. Combination of acoustical radiosity and the image source method

    Koutsouris, Georgios I; Brunskog, Jonas; Jeong, Cheol-Ho

    2013-01-01

    A combined model for room acoustic predictions is developed, aiming to treat both diffuse and specular reflections in a unified way. Two established methods are incorporated: acoustical radiosity, accounting for the diffuse part, and the image source method, accounting for the specular part...

  1. EEG source imaging assists decoding in a face recognition task

    Andersen, Rasmus S.; Eliasen, Anders U.; Pedersen, Nicolai

    2017-01-01

    of face recognition. This task concerns the differentiation of brain responses to images of faces and scrambled faces and poses a rather difficult decoding problem at the single trial level. We implement the pipeline using spatially focused features and show that this approach is challenged and source...

  2. Background gas density and beam losses in NIO1 beam source

    Sartori, E., E-mail: emanuele.sartori@igi.cnr.it; Veltri, P.; Serianni, G. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova (Italy); Cavenago, M. [INFN-LNL, v.le dell’Università 2, I-35020 Legnaro (PD) (Italy)

    2016-02-15

    NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection.

  3. Advanced imaging technology using carbon nanotube x ray source

    Choi, Hae Young; Seol, Seung Kown; Kim, Jaehoon; Yoo, Seung Hoon; Kim, Jong Uk

    2008-01-01

    Recently, X ray imaging technology is a useful and leading medical diagnostic tool for healthcare professionals to diagnose disease in human body. CNTs(i.e. carbon nanotubes)are used in many applications like FED, Micro wave amplifier, X ray source, etc. because of its suitable electrical, chemical and physical properties. Specially, CNTs are well used electron emitters for x ray source. Conventionally, thermionic type of tungsten filament x ray tube is widely employed in the field of bio medical and industrial application fields. However, intrinsic problems such as, poor emission efficiency and low imaging resolution cause the limitation of use of the x ray tube. To fulfill the current market requirement specifically for medical diagnostic field, we have developed rather a portable and compact CNT based x ray source in which high imaging resolution is provided. Electron sources used in X ray tubes should be well focused to the anode target for generation of high quality x ray. In this study, Pierce type x ray generation module was tested based its simulation results using by OPERA 3D code. Pierce type module is composed of cone type electrical lens with its number of them and inner angles of them that shows different results with these parameters. And some preliminary images obtained using the CNT x ray source were obtained. The represented images are the finger bone and teeth in human body. It is clear that the trabeculation shape is observed in finger bone. To obtain the finger bone image, tube currents of 250A at 42kV tube voltage was applied. The human tooth image, however, is somewhat unclear because the supplied voltage to the tube was limited to max. 50kV in the system developed. It should be noted that normally 60∼70kV of tube voltage is supplied in dental imaging. Considering these it should be emphasized that if the tube voltage is over 60kV then clearer image is possible. In this paper, we are discussed comparing between these experiment results and

  4. Dual-source CT cardiac imaging: initial experience

    Johnson, Thorsten R.C.; Nikolaou, Konstantin; Wintersperger, Bernd J.; Rist, Carsten; Buhmann, Sonja; Reiser, Maximilian F.; Becker, Christoph R.; Leber, Alexander W.; Ziegler, Franz von; Knez, Andreas

    2006-01-01

    The relation of heart rate and image quality in the depiction of coronary arteries, heart valves and myocardium was assessed on a dual-source computed tomography system (DSCT). Coronary CT angiography was performed on a DSCT (Somatom Definition, Siemens) with high concentration contrast media (Iopromide, Ultravist 370, Schering) in 24 patients with heart rates between 44 and 92 beats per minute. Images were reconstructed over the whole cardiac cycle in 10% steps. Two readers independently assessed the image quality with regard to the diagnostic evaluation of right and left coronary artery, heart valves and left ventricular myocardium for the assessment of vessel wall changes, coronary stenoses, valve morphology and function and ventricular function on a three point grading scale. The image quality ratings at the optimal reconstruction interval were 1.24±0.42 for the right and 1.09±0.27 for the left coronary artery. A reconstruction of diagnostic systolic and diastolic images is possible for a wide range of heart rates, allowing also a functional evaluation of valves and myocardium. Dual-source CT offers very robust diagnostic image quality in a wide range of heart rates. The high temporal resolution now also makes a functional evaluation of the heart valves and myocardium possible. (orig.)

  5. Three-dimensional tomosynthetic image restoration for brachytherapy source localization

    Persons, Timothy M.

    2001-01-01

    Tomosynthetic image reconstruction allows for the production of a virtually infinite number of slices from a finite number of projection views of a subject. If the reconstructed image volume is viewed in toto, and the three-dimensional (3D) impulse response is accurately known, then it is possible to solve the inverse problem (deconvolution) using canonical image restoration methods (such as Wiener filtering or solution by conjugate gradient least squares iteration) by extension to three dimensions in either the spatial or the frequency domains. This dissertation presents modified direct and iterative restoration methods for solving the inverse tomosynthetic imaging problem in 3D. The significant blur artifact that is common to tomosynthetic reconstructions is deconvolved by solving for the entire 3D image at once. The 3D impulse response is computed analytically using a fiducial reference schema as realized in a robust, self-calibrating solution to generalized tomosynthesis. 3D modulation transfer function analysis is used to characterize the tomosynthetic resolution of the 3D reconstructions. The relevant clinical application of these methods is 3D imaging for brachytherapy source localization. Conventional localization schemes for brachytherapy implants using orthogonal or stereoscopic projection radiographs suffer from scaling distortions and poor visibility of implanted seeds, resulting in compromised source tracking (reported errors: 2-4 mm) and dosimetric inaccuracy. 3D image reconstruction (using a well-chosen projection sampling scheme) and restoration of a prostate brachytherapy phantom is used for testing. The approaches presented in this work localize source centroids with submillimeter error in two Cartesian dimensions and just over one millimeter error in the third

  6. Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

    Meng, Congsen [LaserLaB Amsterdam, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands); Department of Physics, National University of Defense Technology, Changsha 410073 (China); Janssen, Maurice H. M. [LaserLaB Amsterdam, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

    2015-02-15

    Here, we report on femtosecond ion imaging experiments to measure the density profile of a pulsed supersonic molecular beam. Ion images are measured for both a molecular beam and bulk gas under identical experimental conditions via femtosecond multiphoton ionization of Xe atoms. We report the density profile of the molecular beam, and the measured absolute density is compared with theoretical calculations of the centre line beam density. Subsequently, we discuss reasons accounting for the differences between measurements and calculations and propose that strong skimmer interference is the most probable cause for the differences. Furthermore, we report on experiments measuring the centre line density of seeded supersonic beams. The femtosecond ion images show that seeding the heavy Xe atom at low relative seed fractions (1%-10%) in a light carrier gas like Ne results in strong relative enhancements of up to two orders of magnitude.

  7. Studies in High Current Density Ion Sources for Heavy Ion Fusion Applications

    Chacon-Golcher, E.

    2002-01-01

    This dissertation develops diverse research on small (diameter ∼ few mm), high current density (J ∼ several tens of mA/cm 2 ) heavy ion sources. The research has been developed in the context of a programmatic interest within the Heavy Ion Fusion (HIF) Program to explore alternative architectures in the beam injection systems that use the merging of small, bright beams. An ion gun was designed and built for these experiments. Results of average current density yield ( ) at different operating conditions are presented for K + and Cs + contact ionization sources and potassium aluminum silicate sources. Maximum values for a K + beam of ∼90 mA/cm 2 were observed in 2.3 (micro)s pulses. Measurements of beam intensity profiles and emittances are included. Measurements of neutral particle desorption are presented at different operating conditions which lead to a better understanding of the underlying atomic diffusion processes that determine the lifetime of the emitter. Estimates of diffusion times consistent with measurements are presented, as well as estimates of maximum repetition rates achievable. Diverse studies performed on the composition and preparation of alkali aluminosilicate ion sources are also presented. In addition, this work includes preliminary work carried out exploring the viability of an argon plasma ion source and a bismuth metal vapor vacuum arc (MEVVA) ion source. For the former ion source, fast rise-times (∼ 1 (micro)s), high current densities (∼ 100 mA/cm 2 ) and low operating pressures ( e psilon) n (le) 0.006 π mm · mrad) although measured currents differed from the desired ones (I ∼ 5mA) by about a factor of 10

  8. Studies in High Current Density Ion Sources for Heavy Ion Fusion Applications

    Chacon-Golcher, Edwin [Univ. of California, Berkeley, CA (United States)

    2002-06-01

    This dissertation develops diverse research on small (diameter ~ few mm), high current density (J ~ several tens of mA/cm2) heavy ion sources. The research has been developed in the context of a programmatic interest within the Heavy Ion Fusion (HIF) Program to explore alternative architectures in the beam injection systems that use the merging of small, bright beams. An ion gun was designed and built for these experiments. Results of average current density yield () at different operating conditions are presented for K+ and Cs+ contact ionization sources and potassium aluminum silicate sources. Maximum values for a K+ beam of ~90 mA/cm2 were observed in 2.3 μs pulses. Measurements of beam intensity profiles and emittances are included. Measurements of neutral particle desorption are presented at different operating conditions which lead to a better understanding of the underlying atomic diffusion processes that determine the lifetime of the emitter. Estimates of diffusion times consistent with measurements are presented, as well as estimates of maximum repetition rates achievable. Diverse studies performed on the composition and preparation of alkali aluminosilicate ion sources are also presented. In addition, this work includes preliminary work carried out exploring the viability of an argon plasma ion source and a bismuth metal vapor vacuum arc (MEVVA) ion source. For the former ion source, fast rise-times (~ 1 μs), high current densities (~ 100 mA/cm+) and low operating pressures (< 2 mtorr) were verified. For the latter, high but acceptable levels of beam emittance were measured (εn ≤ 0.006 π· mm · mrad) although measured currents differed from the desired ones (I ~ 5mA) by about a factor of 10.

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

    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

  10. Bulk density estimation using a 3-dimensional image acquisition and analysis system

    Heyduk Adam

    2016-01-01

    Full Text Available The paper presents a concept of dynamic bulk density estimation of a particulate matter stream using a 3-d image analysis system and a conveyor belt scale. A method of image acquisition should be adjusted to the type of scale. The paper presents some laboratory results of static bulk density measurements using the MS Kinect time-of-flight camera and OpenCV/Matlab software. Measurements were made for several different size classes.

  11. Obtention of scintillography images by low density lipoproteins labelled with technetium 99

    Silva, S.; Coelho, I.; Zanardo, E.; Pileggi, F.; Meneguethi, C.; Maranhao, R.C.

    1992-01-01

    The low density lipoproteins carry the most part of the cholesterol in the blood plasma. These lipoproteins are labelled with technetium-99-m and have been used for obtaining images in nuclear medicine. The introduction of this technique is presented, aiming futures clinical uses. Scintillographic images are obtained 25 minutes and 24 hours after the injection of 3 m Ci of low density lipoproteins - technetium-99 m in rabbits. (C.G.C.)

  12. Image Harvest: an open-source platform for high-throughput plant image processing and analysis.

    Knecht, Avi C; Campbell, Malachy T; Caprez, Adam; Swanson, David R; Walia, Harkamal

    2016-05-01

    High-throughput plant phenotyping is an effective approach to bridge the genotype-to-phenotype gap in crops. Phenomics experiments typically result in large-scale image datasets, which are not amenable for processing on desktop computers, thus creating a bottleneck in the image-analysis pipeline. Here, we present an open-source, flexible image-analysis framework, called Image Harvest (IH), for processing images originating from high-throughput plant phenotyping platforms. Image Harvest is developed to perform parallel processing on computing grids and provides an integrated feature for metadata extraction from large-scale file organization. Moreover, the integration of IH with the Open Science Grid provides academic researchers with the computational resources required for processing large image datasets at no cost. Image Harvest also offers functionalities to extract digital traits from images to interpret plant architecture-related characteristics. To demonstrate the applications of these digital traits, a rice (Oryza sativa) diversity panel was phenotyped and genome-wide association mapping was performed using digital traits that are used to describe different plant ideotypes. Three major quantitative trait loci were identified on rice chromosomes 4 and 6, which co-localize with quantitative trait loci known to regulate agronomically important traits in rice. Image Harvest is an open-source software for high-throughput image processing that requires a minimal learning curve for plant biologists to analyzephenomics datasets. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  13. Image Harvest: an open-source platform for high-throughput plant image processing and analysis

    Knecht, Avi C.; Campbell, Malachy T.; Caprez, Adam; Swanson, David R.; Walia, Harkamal

    2016-01-01

    High-throughput plant phenotyping is an effective approach to bridge the genotype-to-phenotype gap in crops. Phenomics experiments typically result in large-scale image datasets, which are not amenable for processing on desktop computers, thus creating a bottleneck in the image-analysis pipeline. Here, we present an open-source, flexible image-analysis framework, called Image Harvest (IH), for processing images originating from high-throughput plant phenotyping platforms. Image Harvest is developed to perform parallel processing on computing grids and provides an integrated feature for metadata extraction from large-scale file organization. Moreover, the integration of IH with the Open Science Grid provides academic researchers with the computational resources required for processing large image datasets at no cost. Image Harvest also offers functionalities to extract digital traits from images to interpret plant architecture-related characteristics. To demonstrate the applications of these digital traits, a rice (Oryza sativa) diversity panel was phenotyped and genome-wide association mapping was performed using digital traits that are used to describe different plant ideotypes. Three major quantitative trait loci were identified on rice chromosomes 4 and 6, which co-localize with quantitative trait loci known to regulate agronomically important traits in rice. Image Harvest is an open-source software for high-throughput image processing that requires a minimal learning curve for plant biologists to analyzephenomics datasets. PMID:27141917

  14. Proton density-weighted MR imaging of the knee: fat suppression versus without fat suppression

    Lee, So-Yeon; Kim, Sun Ki; Jee, Won-Hee; Kim, Jung-Man

    2011-01-01

    To prospectively evaluate the diagnostic accuracy of proton density-weighted imaging with and without fat suppression for detecting meniscal tears. The study involved 48 patients who underwent arthroscopy less than 3 months after proton density-weighted imaging with and without fat suppression. Sagittal images were independently reviewed by two radiologists for the presence of meniscal tears. Medial and lateral menisci were separately analyzed in terms of anterior horn, body, and posterior horn. Interobserver agreement was assessed using κ coefficients. The McNemar test was used to determine any differences between the two methods in terms of sensitivity and specificity. Arthroscopy findings were used as the diagnostic reference standard. Arthroscopy revealed 71 tears involving 85 meniscal segments: 34 medial meniscal segments and 51 lateral meniscal segments. The sensitivity, specificity, and accuracy of each radiologist were 95% (81/85), 92% (186/203), and 93% (267/288), and 93% (79/85), 93% (189/203), and 93% (268/288) when using fat-suppressed proton density-weighted imaging, and 91% (77/85), 93% (189/203), and 92% (266/288), and 91% (77/85), 93% (188/203), and 92% (265/288) when using proton density-weighted imaging without fat suppression, respectively. Interobserver agreement for meniscal tears was very high with proton-weighted imaging with (κ = 0.87) or without (κ = 0.86) fat suppression. There were no significant differences for detection of medial meniscal tears when using proton density-weighted imaging with or without fat suppression for both readers (p > 0.05). Fat-suppressed proton density-weighted imaging can replace proton density-weighted imaging without fat suppression for the detection of meniscal tears. (orig.)

  15. Proton density-weighted MR imaging of the knee: fat suppression versus without fat suppression

    Lee, So-Yeon; Kim, Sun Ki [Catholic University of Korea, Department of Radiology, Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Jee, Won-Hee [Catholic University of Korea, Department of Radiology, Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Catholic University of Korea, Diagnostic Radiology, Seoul St. Mary' s Hospital, School of Medicine, Seoul (Korea, Republic of); Kim, Jung-Man [Catholic University of Korea, Department of Orthopedic Surgery, Seoul St. Mary' s Hospital, Seoul (Korea, Republic of)

    2011-02-15

    To prospectively evaluate the diagnostic accuracy of proton density-weighted imaging with and without fat suppression for detecting meniscal tears. The study involved 48 patients who underwent arthroscopy less than 3 months after proton density-weighted imaging with and without fat suppression. Sagittal images were independently reviewed by two radiologists for the presence of meniscal tears. Medial and lateral menisci were separately analyzed in terms of anterior horn, body, and posterior horn. Interobserver agreement was assessed using {kappa} coefficients. The McNemar test was used to determine any differences between the two methods in terms of sensitivity and specificity. Arthroscopy findings were used as the diagnostic reference standard. Arthroscopy revealed 71 tears involving 85 meniscal segments: 34 medial meniscal segments and 51 lateral meniscal segments. The sensitivity, specificity, and accuracy of each radiologist were 95% (81/85), 92% (186/203), and 93% (267/288), and 93% (79/85), 93% (189/203), and 93% (268/288) when using fat-suppressed proton density-weighted imaging, and 91% (77/85), 93% (189/203), and 92% (266/288), and 91% (77/85), 93% (188/203), and 92% (265/288) when using proton density-weighted imaging without fat suppression, respectively. Interobserver agreement for meniscal tears was very high with proton-weighted imaging with ({kappa} = 0.87) or without ({kappa} = 0.86) fat suppression. There were no significant differences for detection of medial meniscal tears when using proton density-weighted imaging with or without fat suppression for both readers (p > 0.05). Fat-suppressed proton density-weighted imaging can replace proton density-weighted imaging without fat suppression for the detection of meniscal tears. (orig.)

  16. Imaging choroidal neovascular membrane using en face swept-source optical coherence tomography angiography

    Moussa M

    2017-10-01

    Full Text Available Magdy Moussa,1,2 Mahmoud Leila,3 Hagar Khalid1,2 1Ophthalmology Department, Faculty of Medicine, Tanta University, Tanta, Egypt; 2MEDIC Eye Center, Tanta, Egypt; 3Retina Department, Research Institute of Ophthalmology, Giza, Egypt Purpose: The aim of this study was to assess the efficacy of swept-source optical coherence tomography angiography (SS-OCTA in delineating the morphology of choroidal neovascular membrane (CNV. Patients and methods: This was a retrospective observational case series reviewing clinical data and fundus fluorescein angiography (FFA, swept-source optical coherence tomography (SS-OCT, and SS-OCTA images of patients with CNV and comparing the findings. The swept-source technology enables deeper penetration and superior axial resolution. The incorporated blood flow detection algorithm, optical coherence tomography angiography ratio analysis (OCTARA, enables visualization of CNV in vivo without the need for dye injection. Results: The study included 136 eyes of 105 patients. Active lesions on SS-OCTA images showed increased capillary density, extensive arborization, vascular anastomosis and looping, and peri-lesional hollow. Inactive lesions showed decreased capillary density, presence of large linear vessels, and presence of feeder vessels supplying the CNV. We detected positive correlation between SS-OCTA, FFA, and SS-OCT images in 97% of eyes. In the remaining 3%, SS-OCTA confirmed the absence of CNV, whereas FFA and SS-OCT either were inconclusive in the diagnosis of CNV or yielded false-positive results. Conclusion: SS-OCT and SS-OCTA represent a reproducible risk-free analog for FFA in imaging CNV. SS-OCTA is particularly versatile in cases where FFA and SS-OCT are inconclusive. Keywords: swept-source OCT, OCT angiography, imaging of CNV, OCTARA algorithm

  17. Open source tools for standardized privacy protection of medical images

    Lien, Chung-Yueh; Onken, Michael; Eichelberg, Marco; Kao, Tsair; Hein, Andreas

    2011-03-01

    In addition to the primary care context, medical images are often useful for research projects and community healthcare networks, so-called "secondary use". Patient privacy becomes an issue in such scenarios since the disclosure of personal health information (PHI) has to be prevented in a sharing environment. In general, most PHIs should be completely removed from the images according to the respective privacy regulations, but some basic and alleviated data is usually required for accurate image interpretation. Our objective is to utilize and enhance these specifications in order to provide reliable software implementations for de- and re-identification of medical images suitable for online and offline delivery. DICOM (Digital Imaging and Communications in Medicine) images are de-identified by replacing PHI-specific information with values still being reasonable for imaging diagnosis and patient indexing. In this paper, this approach is evaluated based on a prototype implementation built on top of the open source framework DCMTK (DICOM Toolkit) utilizing standardized de- and re-identification mechanisms. A set of tools has been developed for DICOM de-identification that meets privacy requirements of an offline and online sharing environment and fully relies on standard-based methods.

  18. Numerical simulation of logging-while-drilling density image by Monte-Carlo method

    Yue Aizhong; He Biao; Zhang Jianmin; Wang Lijuan

    2010-01-01

    Logging-while-drilling system is researched by Monte Carlo Method. Model of Logging-while-drilling system is built, tool response and azimuth density image are acquired, methods dealing with azimuth density data is discussed. This outcome lay foundation for optimizing tool, developing new tool and logging explanation. (authors)

  19. Seismic reflection imaging with conventional and unconventional sources

    Quiros Ugalde, Diego Alonso

    This manuscript reports the results of research using both conventional and unconventional energy sources as well as conventional and unconventional analysis to image crustal structure using reflected seismic waves. The work presented here includes the use of explosions to investigate the Taiwanese lithosphere, the use of 'noise' from railroads to investigate the shallow subsurface of the Rio Grande rift, and the use of microearthquakes to image subsurface structure near an active fault zone within the Appalachian mountains. Chapter 1 uses recordings from the land refraction and wide-angle reflection component of the Taiwan Integrated Geodynamic Research (TAIGER) project. The most prominent reflection feature imaged by these surveys is an anomalously strong reflector found in northeastern Taiwan. The goal of this chapter is to analyze the TAIGER recordings and to place the reflector into a geologic framework that fits with the modern tectonic kinematics of the region. Chapter 2 uses railroad traffic as a source for reflection profiling within the Rio Grande rift. Here the railroad recordings are treated in an analogous way to Vibroseis recordings. These results suggest that railroad noise in general can be a valuable new tool in imaging and characterizing the shallow subsurface in environmental and geotechnical studies. In chapters 3 and 4, earthquakes serve as the seismic imaging source. In these studies the methodology of Vertical Seismic Profiling (VSP) is borrowed from the oil and gas industry to develop reflection images. In chapter 3, a single earthquake is used to probe a small area beneath Waterboro, Maine. In chapter 4, the same method is applied to multiple earthquakes to take advantage of the increased redundancy that results from multiple events illuminating the same structure. The latter study demonstrates how dense arrays can be a powerful new tool for delineating, and monitoring temporal changes of deep structure in areas characterized by significant

  20. Gamma-ray imaging of the Quinby sources

    Gregor, J.; Hensley, D.C.

    1996-01-01

    The Quinby sources are alumina cylinders 7 inches in diameter and 8 inches high doped with weapons grade plutonium. We describe a computer tomography system for reconstructing three-dimensional images of these sources. Each reconstruction maps the spatial distribution of the internal [sup 241]Am gamma ray activity and is computed using an iterative, expectation-maximization algorithm with detection efficiencies based both on geometric model of the experimental setup and attenuation corrections. Constructed about a decade ago, the Quinby sources were to contain uniformly distributed material. However, for some of the sources we have found regions where the plutonium solution, tends to be concentrated. The ultimate goal of this work is to provide the basis for self-shielding corrections when analyzing differential dieaway neutron measurements

  1. The utilization of dual source CT in imaging of polytrauma

    Nicolaou, S. [University of British Columbia, Vancouver General Hospital, Department of Radiology, 899 West 12th Avenue, Vancouver, British Columbia, V5Z1M9 (Canada)], E-mail: savvas.nicolaou@vch.ca; Eftekhari, A.; Sedlic, T.; Hou, D.J.; Mudri, M.J.; Aldrich, John; Louis, L. [University of British Columbia, Vancouver General Hospital, Department of Radiology, 899 West 12th Avenue, Vancouver, British Columbia, V5Z1M9 (Canada)

    2008-12-15

    Despite the growing role of imaging, trauma remains the leading cause of death in people below the age of 45 years in the western industrialized countries. Trauma has been touted as the largest epidemic in the 20th century. The advent of MDCT has been the greatest advance in trauma care in the last 25 years. However, there are still challenges in CT imaging of the polytrauma individual including time restraints, diagnostic errors, radiation dose effects and bridging the gap between anatomy and physiology. This article will analyze these challenges and provide possible solutions offered by the unique design of the dual source CT scanner.

  2. The utilization of dual source CT in imaging of polytrauma

    Nicolaou, S.; Eftekhari, A.; Sedlic, T.; Hou, D.J.; Mudri, M.J.; Aldrich, John; Louis, L.

    2008-01-01

    Despite the growing role of imaging, trauma remains the leading cause of death in people below the age of 45 years in the western industrialized countries. Trauma has been touted as the largest epidemic in the 20th century. The advent of MDCT has been the greatest advance in trauma care in the last 25 years. However, there are still challenges in CT imaging of the polytrauma individual including time restraints, diagnostic errors, radiation dose effects and bridging the gap between anatomy and physiology. This article will analyze these challenges and provide possible solutions offered by the unique design of the dual source CT scanner

  3. Probability density function modeling of scalar mixing from concentrated sources in turbulent channel flow

    Bakosi, J.; Franzese, P.; Boybeyi, Z.

    2010-01-01

    Dispersion of a passive scalar from concentrated sources in fully developed turbulent channel flow is studied with the probability density function (PDF) method. The joint PDF of velocity, turbulent frequency and scalar concentration is represented by a large number of Lagrangian particles. A stochastic near-wall PDF model combines the generalized Langevin model of Haworth & Pope with Durbin's method of elliptic relaxation to provide a mathematically exact treatment of convective and viscous ...

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

    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. Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

    Meng, C.; Janssen, M.H.M.

    2015-01-01

    Here, we report on femtosecond ion imaging experiments to measure the density profile of a pulsed supersonic molecular beam. Ion images are measured for both a molecular beam and bulk gas under identical experimental conditions via femtosecond multiphoton ionization of Xe atoms. We report the

  6. Linearized image reconstruction method for ultrasound modulated electrical impedance tomography based on power density distribution

    Song, Xizi; Xu, Yanbin; Dong, Feng

    2017-01-01

    Electrical resistance tomography (ERT) is a promising measurement technique with important industrial and clinical applications. However, with limited effective measurements, it suffers from poor spatial resolution due to the ill-posedness of the inverse problem. Recently, there has been an increasing research interest in hybrid imaging techniques, utilizing couplings of physical modalities, because these techniques obtain much more effective measurement information and promise high resolution. Ultrasound modulated electrical impedance tomography (UMEIT) is one of the newly developed hybrid imaging techniques, which combines electric and acoustic modalities. A linearized image reconstruction method based on power density is proposed for UMEIT. The interior data, power density distribution, is adopted to reconstruct the conductivity distribution with the proposed image reconstruction method. At the same time, relating the power density change to the change in conductivity, the Jacobian matrix is employed to make the nonlinear problem into a linear one. The analytic formulation of this Jacobian matrix is derived and its effectiveness is also verified. In addition, different excitation patterns are tested and analyzed, and opposite excitation provides the best performance with the proposed method. Also, multiple power density distributions are combined to implement image reconstruction. Finally, image reconstruction is implemented with the linear back-projection (LBP) algorithm. Compared with ERT, with the proposed image reconstruction method, UMEIT can produce reconstructed images with higher quality and better quantitative evaluation results. (paper)

  7. IMAGING SPECTROSCOPY ON PREFLARE CORONAL NONTHERMAL SOURCES ASSOCIATED WITH THE 2002 JULY 23 FLARE

    Asai, Ayumi; Nakajima, Hiroshi; Shimojo, Masumi; Yokoyama, Takaaki; Masuda, Satoshi; Krucker, Saem

    2009-01-01

    We present a detailed examination on the coronal nonthermal emissions during the preflare phase of the X4.8 flare that occurred on 2002 July 23. The microwave (17 GHz and 34 GHz) data obtained with Nobeyama Radioheliograph, at Nobeyama Solar Radio Observatory and the hard X-ray (HXR) data taken with RHESSI obviously showed nonthermal sources that are located above the flare loops during the preflare phase. We performed imaging spectroscopic analyses on the nonthermal emission sources both in microwaves and in HXRs, and confirmed that electrons are accelerated from several tens of keV to more than 1 MeV even in this phase. If we assume the thin-target model for the HXR emission source, the derived electron spectral indices (∼4.7) is the same value as that from microwaves (∼4.7) within the observational uncertainties, which implies that the distribution of the accelerated electrons follows a single power law. The number density of the microwave-emitting electrons is, however, larger than that of the HXR-emitting electrons, unless we assume low-ambient plasma density of about 1.0 x 10 9 cm -3 for the HXR-emitting region. If we adopt the thick-target model for the HXR emission source, on the other hand, the electron spectral index (∼6.7) is much different, while the gap of the number density of the accelerated electrons is somewhat reduced.

  8. LORETA current source density for duration mismatch negativity and neuropsychological assessment in early schizophrenia.

    Tomohiro Miyanishi

    Full Text Available INTRODUCTION: Patients with schizophrenia elicit cognitive decline from the early phase of the illness. Mismatch negativity (MMN has been shown to be associated with cognitive function. We investigated the current source density of duration mismatch negativity (dMMN, by using low-resolution brain electromagnetic tomography (LORETA, and neuropsychological performance in subjects with early schizophrenia. METHODS: Data were obtained from 20 patients meeting DSM-IV criteria for schizophrenia or schizophreniform disorder, and 20 healthy control (HC subjects. An auditory odd-ball paradigm was used to measure dMMN. Neuropsychological performance was evaluated by the brief assessment of cognition in schizophrenia Japanese version (BACS-J. RESULTS: Patients showed smaller dMMN amplitudes than those in the HC subjects. LORETA current density for dMMN was significantly lower in patients compared to HC subjects, especially in the temporal lobes. dMMN current density in the frontal lobe was positively correlated with working memory performance in patients. CONCLUSIONS: This is the first study to identify brain regions showing smaller dMMN current density in early schizophrenia. Further, poor working memory was associated with decreased dMMN current density in patients. These results are likely to help understand the neural basis for cognitive impairment of schizophrenia.

  9. Distributed Source Coding Techniques for Lossless Compression of Hyperspectral Images

    Barni Mauro

    2007-01-01

    Full Text Available This paper deals with the application of distributed source coding (DSC theory to remote sensing image compression. Although DSC exhibits a significant potential in many application fields, up till now the results obtained on real signals fall short of the theoretical bounds, and often impose additional system-level constraints. The objective of this paper is to assess the potential of DSC for lossless image compression carried out onboard a remote platform. We first provide a brief overview of DSC of correlated information sources. We then focus on onboard lossless image compression, and apply DSC techniques in order to reduce the complexity of the onboard encoder, at the expense of the decoder's, by exploiting the correlation of different bands of a hyperspectral dataset. Specifically, we propose two different compression schemes, one based on powerful binary error-correcting codes employed as source codes, and one based on simpler multilevel coset codes. The performance of both schemes is evaluated on a few AVIRIS scenes, and is compared with other state-of-the-art 2D and 3D coders. Both schemes turn out to achieve competitive compression performance, and one of them also has reduced complexity. Based on these results, we highlight the main issues that are still to be solved to further improve the performance of DSC-based remote sensing systems.

  10. Accommodating multiple illumination sources in an imaging colorimetry environment

    Tobin, Kenneth W., Jr.; Goddard, James S., Jr.; Hunt, Martin A.; Hylton, Kathy W.; Karnowski, Thomas P.; Simpson, Marc L.; Richards, Roger K.; Treece, Dale A.

    2000-03-01

    Researchers at the Oak Ridge National Laboratory have been developing a method for measuring color quality in textile products using a tri-stimulus color camera system. Initial results of the Imaging Tristimulus Colorimeter (ITC) were reported during 1999. These results showed that the projection onto convex sets (POCS) approach to color estimation could be applied to complex printed patterns on textile products with high accuracy and repeatability. Image-based color sensors used for on-line measurement are not colorimetric by nature and require a non-linear transformation of the component colors based on the spectral properties of the incident illumination, imaging sensor, and the actual textile color. Our earlier work reports these results for a broad-band, smoothly varying D65 standard illuminant. To move the measurement to the on-line environment with continuously manufactured textile webs, the illumination source becomes problematic. The spectral content of these light sources varies substantially from the D65 standard illuminant and can greatly impact the measurement performance of the POCS system. Although absolute color measurements are difficult to make under different illumination, referential measurements to monitor color drift provide a useful indication of product quality. Modifications to the ITC system have been implemented to enable the study of different light sources. These results and the subsequent analysis of relative color measurements will be reported for textile products.

  11. CMP reflection imaging via interferometry of distributed subsurface sources

    Kim, D.; Brown, L. D.; Quiros, D. A.

    2015-12-01

    The theoretical foundations of recovering body wave energy via seismic interferometry are well established. However in practice, such recovery remains problematic. Here, synthetic seismograms computed for subsurface sources are used to evaluate the geometrical combinations of realistic ambient source and receiver distributions that result in useful recovery of virtual body waves. This study illustrates how surface receiver arrays that span a limited distribution suite of sources, can be processed to reproduce virtual shot gathers that result in CMP gathers which can be effectively stacked with traditional normal moveout corrections. To verify the feasibility of the approach in practice, seismic recordings of 50 aftershocks following the magnitude of 5.8 Virginia earthquake occurred in August, 2011 have been processed using seismic interferometry to produce seismic reflection images of the crustal structure above and beneath the aftershock cluster. Although monotonic noise proved to be problematic by significantly reducing the number of usable recordings, the edited dataset resulted in stacked seismic sections characterized by coherent reflections that resemble those seen on a nearby conventional reflection survey. In particular, "virtual" reflections at travel times of 3 to 4 seconds suggest reflector sat approximately 7 to 12 km depth that would seem to correspond to imbricate thrust structures formed during the Appalachian orogeny. The approach described here represents a promising new means of body wave imaging of 3D structure that can be applied to a wide array of geologic and energy problems. Unlike other imaging techniques using natural sources, this technique does not require precise source locations or times. It can thus exploit aftershocks too small for conventional analyses. This method can be applied to any type of microseismic cloud, whether tectonic, volcanic or man-made.

  12. Quantitative assessment of periimplant bone density (HU) on CBCT image

    Goo, Jong Gook; Kim, Jin Soo; Kim, Jae Duk

    2008-01-01

    The primary aims of this retrospective study were to compare subjective bone quality and bone quality based on the Hounsfield scale in different segments of the edentulous jaw, and to establish quantitative and objective assessment of the bone quality. Twenty eight randomly selected cone-beam computed tomographic (CBCT) scans were analyzed. For evaluation one hundred and twelve edentulous areas were selected. Implant recipient sites were evaluated visually for Lekholm and Zarb classification. The same sites were subsequently evaluated digitally using the Hounsfield scale with Vimplant 2.0 TM , and the results were correlated with visual classification. Data was subject for statistical analysis in order to determine correlation between recorded HU and the regions of the mouth with the Kruskal-Wallis test. The highest unit/mean density value (311 HU) was found in the anterior mandible, followed by 259 HU for the posterior mandible, 216 HU for the anterior maxilla, and 127 HU for the posterior maxilla. These results demonstrate a strong correlation for HU depending on the region of the mouth (p TM with Vimplant TM software.

  13. Image transmission system using adaptive joint source and channel decoding

    Liu, Weiliang; Daut, David G.

    2005-03-01

    In this paper, an adaptive joint source and channel decoding method is designed to accelerate the convergence of the iterative log-dimain sum-product decoding procedure of LDPC codes as well as to improve the reconstructed image quality. Error resilience modes are used in the JPEG2000 source codec, which makes it possible to provide useful source decoded information to the channel decoder. After each iteration, a tentative decoding is made and the channel decoded bits are then sent to the JPEG2000 decoder. Due to the error resilience modes, some bits are known to be either correct or in error. The positions of these bits are then fed back to the channel decoder. The log-likelihood ratios (LLR) of these bits are then modified by a weighting factor for the next iteration. By observing the statistics of the decoding procedure, the weighting factor is designed as a function of the channel condition. That is, for lower channel SNR, a larger factor is assigned, and vice versa. Results show that the proposed joint decoding methods can greatly reduce the number of iterations, and thereby reduce the decoding delay considerably. At the same time, this method always outperforms the non-source controlled decoding method up to 5dB in terms of PSNR for various reconstructed images.

  14. Measurements of beam current density and proton fraction of a permanent-magnet microwave ion source

    Waldmann, Ole; Ludewigt, Bernhard [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2011-11-15

    A permanent-magnet microwave ion source has been built for use in a high-yield, compact neutron generator. The source has been designed to produce up to 100 mA of deuterium and tritium ions. The electron-cyclotron resonance condition is met at a microwave frequency of 2.45 GHz and a magnetic field strength of 87.5 mT. The source operates at a low hydrogen gas pressure of about 0.15 Pa. Hydrogen beams with a current density of 40 mA/cm{sup 2} have been extracted at a microwave power of 450 W. The dependence of the extracted proton beam fraction on wall materials and operating parameters was measured and found to vary from 45% for steel to 95% for boron nitride as a wall liner material.

  15. Measurements of beam current density and proton fraction of a permanent-magnet microwave ion source.

    Waldmann, Ole; Ludewigt, Bernhard

    2011-11-01

    A permanent-magnet microwave ion source has been built for use in a high-yield, compact neutron generator. The source has been designed to produce up to 100 mA of deuterium and tritium ions. The electron-cyclotron resonance condition is met at a microwave frequency of 2.45 GHz and a magnetic field strength of 87.5 mT. The source operates at a low hydrogen gas pressure of about 0.15 Pa. Hydrogen beams with a current density of 40 mA/cm(2) have been extracted at a microwave power of 450 W. The dependence of the extracted proton beam fraction on wall materials and operating parameters was measured and found to vary from 45% for steel to 95% for boron nitride as a wall liner material. © 2011 American Institute of Physics

  16. Source imaging of drums in the APNEA system

    Hensley, D.

    1995-01-01

    The APNea System is a neutron assay device utilizing both a passive mode and a differential-dieaway active mode. The total detection efficiency is not spatially uniform, even for an empty chamber, and a drum matrix in the chamber can severely distort this response. In order to achieve a response which is independent of the way the source material is distributed in a drum, an imaging procedure has been developed which treats the drum as a number of virtual (sub)volumes. Since each virtual volume of source material is weighted with the appropriate instrument parameters (detection efficiency and thermal flux), the final assay result is essentially independent of the actual distribution of the source material throughout the drum and its matrix

  17. Diffraction-enhanced imaging at the UK synchrotron radiation source

    Ibison, M.; Cheung, K.C.; Siu, K.; Hall, C.J.; Lewis, R.A.; Hufton, A.; Wilkinson, S.J.; Rogers, K.D.; Round, A.

    2005-01-01

    The Diffraction-Enhanced Imaging (DEI) system, which shares access to Beamline 7.6 on the Daresbury Synchrotron Radiation Source (SRS), is now in its third year of existence. The system was developed under a European Commission grant PHase Analyser SYstem (PHASY), won during the Fourth Framework. Typical applications continue to be the imaging of small biological specimens, using a beam of 12-17 keV after monochromation and up to 40 mm in width and 1-2 mm in height, although it is planned to investigate other materials as opportunity permits and time becomes available for more routine scientific use. Recent improvements have been made to the optical alignment procedure for setting up the station before imaging: a small laser device can now be set up to send a beam down the X-ray path through the four crystals, and a small photodiode, which has much better signal-to-noise characteristics than the ion chamber normally used for alignment, has been trailed successfully. A 3-D tomographic reconstruction capability has recently been developed and tested for DEI projection image sets, and will be applied to future imaging work on the SRS, in conjunction with volume visualization software. The next generation of DEI system, planned to operate at up to 60 keV on an SRS wiggler station, is in its design stage; it will feature much improved mechanics and mountings, especially for angular control, and a simplified alignment procedure to facilitate the necessary sharing of the SRS station

  18. Open-source software platform for medical image segmentation applications

    Namías, R.; D'Amato, J. P.; del Fresno, M.

    2017-11-01

    Segmenting 2D and 3D images is a crucial and challenging problem in medical image analysis. Although several image segmentation algorithms have been proposed for different applications, no universal method currently exists. Moreover, their use is usually limited when detection of complex and multiple adjacent objects of interest is needed. In addition, the continually increasing volumes of medical imaging scans require more efficient segmentation software design and highly usable applications. In this context, we present an extension of our previous segmentation framework which allows the combination of existing explicit deformable models in an efficient and transparent way, handling simultaneously different segmentation strategies and interacting with a graphic user interface (GUI). We present the object-oriented design and the general architecture which consist of two layers: the GUI at the top layer, and the processing core filters at the bottom layer. We apply the framework for segmenting different real-case medical image scenarios on public available datasets including bladder and prostate segmentation from 2D MRI, and heart segmentation in 3D CT. Our experiments on these concrete problems show that this framework facilitates complex and multi-object segmentation goals while providing a fast prototyping open-source segmentation tool.

  19. Voxel-wise prostate cell density prediction using multiparametric magnetic resonance imaging and machine learning.

    Sun, Yu; Reynolds, Hayley M; Wraith, Darren; Williams, Scott; Finnegan, Mary E; Mitchell, Catherine; Murphy, Declan; Haworth, Annette

    2018-04-26

    There are currently no methods to estimate cell density in the prostate. This study aimed to develop predictive models to estimate prostate cell density from multiparametric magnetic resonance imaging (mpMRI) data at a voxel level using machine learning techniques. In vivo mpMRI data were collected from 30 patients before radical prostatectomy. Sequences included T2-weighted imaging, diffusion-weighted imaging and dynamic contrast-enhanced imaging. Ground truth cell density maps were computed from histology and co-registered with mpMRI. Feature extraction and selection were performed on mpMRI data. Final models were fitted using three regression algorithms including multivariate adaptive regression spline (MARS), polynomial regression (PR) and generalised additive model (GAM). Model parameters were optimised using leave-one-out cross-validation on the training data and model performance was evaluated on test data using root mean square error (RMSE) measurements. Predictive models to estimate voxel-wise prostate cell density were successfully trained and tested using the three algorithms. The best model (GAM) achieved a RMSE of 1.06 (± 0.06) × 10 3 cells/mm 2 and a relative deviation of 13.3 ± 0.8%. Prostate cell density can be quantitatively estimated non-invasively from mpMRI data using high-quality co-registered data at a voxel level. These cell density predictions could be used for tissue classification, treatment response evaluation and personalised radiotherapy.

  20. Multishot echo-planar MREIT for fast imaging of conductivity, current density, and electric field distributions.

    Chauhan, Munish; Vidya Shankar, Rohini; Ashok Kumar, Neeta; Kodibagkar, Vikram D; Sadleir, Rosalind

    2018-01-01

    Magnetic resonance electrical impedance tomography (MREIT) sequences typically use conventional spin or gradient echo-based acquisition methods for reconstruction of conductivity and current density maps. Use of MREIT in functional and electroporation studies requires higher temporal resolution and faster sequences. Here, single and multishot echo planar imaging (EPI) based MREIT sequences were evaluated to see whether high-quality MREIT phase data could be obtained for rapid reconstruction of current density, conductivity, and electric fields. A gel phantom with an insulating inclusion was used as a test object. Ghost artifact, geometric distortion, and MREIT correction algorithms were applied to the data. The EPI-MREIT-derived phase-projected current density and conductivity images were compared with simulations and spin-echo images as a function of EPI shot number. Good agreement among measures in simulated, spin echo, and EPI data was achieved. Current density errors were stable and below 9% as the shot number decreased from 64 to 2, but increased for single-shot images. Conductivity reconstruction relative contrast ratios were stable as the shot number decreased. The derived electric fields also agreed with the simulated data. The EPI methods can be combined successfully with MREIT reconstruction algorithms to achieve fast imaging of current density, conductivity, and electric field. Magn Reson Med 79:71-82, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  1. Impurities, temperature, and density in a miniature electrostatic plasma and current source

    Den Hartog, D.J.; Craig, D.J.; Fiksel, G.; Sarff, J.S.

    1996-10-01

    We have spectroscopically investigated the Sterling Scientific miniature electrostatic plasma source-a plasma gun. This gun is a clean source of high density (10 19 - 10 20 m -3 ), low temperature (5 - 15 eV) plasma. A key result of our investigation is that molybdenum from the gun electrodes is largely trapped in the internal gun discharge; only a small amount escapes in the plasma flowing out of the gun. In addition, the gun plasma parameters actually improve (even lower impurity contamination and higher ion temperature) when up to 1 kA of electron current is extracted from the gun via the application of an external bias. This improvement occurs because the internal gun anode no longer acts as the current return for the internal gun discharge. The gun plasma is a virtual plasma electrode capable of sourcing an electron emission current density of 1 kA/cm 2 . The high emission current, small size (3 - 4 cm diameter), and low impurity generation make this gun attractive for a variety of fusion and plasma technology applications

  2. Thulium heat source for high-endurance and high-energy density power systems

    Walter, C.E.; Kammeraad, J.E.; Van Konynenburg, R.; VanSant, J.H.

    1991-05-01

    We are studying the performance characteristics of radioisotope heat source designs for high-endurance and high-energy-density power systems that use thulium-170. Heat sources in the power range of 5--50 kW th coupled with a power conversion efficiency of ∼30%, can easily satisfy current missions for autonomous underwater vehicles. New naval missions will be possible because thulium isotope power systems have a factor of one-to-two hundred higher endurance and energy density than chemical and electrochemical systems. Thulium-170 also has several other attractive features, including the fact that it decays to stable ytterbium-170 with a half-life of four months. For terrestrial applications, refueling on that time scale should be acceptable in view of the advantage of its benign decay. The heat source designs we are studying account for the requirements of isotope production, shielding, and integration with power conversion components. These requirements are driven by environmental and safety considerations. Thulium is present in the form of thin refractory thulia disks that allow power conversion at high peak temperature. We give estimates of power system state points, performance, mass, and volume characteristics. Monte Carlo radiation analysis provides a detailed assessment of shield requirements and heat transfer under normal and distressed conditions is also considered. 11 refs., 7 figs., 4 tabs

  3. Cardiac magnetic source imaging based on current multipole model

    Tang Fa-Kuan; Wang Qian; Hua Ning; Lu Hong; Tang Xue-Zheng; Ma Ping

    2011-01-01

    It is widely accepted that the heart current source can be reduced into a current multipole. By adopting three linear inverse methods, the cardiac magnetic imaging is achieved in this article based on the current multipole model expanded to the first order terms. This magnetic imaging is realized in a reconstruction plane in the centre of human heart, where the current dipole array is employed to represent realistic cardiac current distribution. The current multipole as testing source generates magnetic fields in the measuring plane, serving as inputs of cardiac magnetic inverse problem. In the heart-torso model constructed by boundary element method, the current multipole magnetic field distribution is compared with that in the homogeneous infinite space, and also with the single current dipole magnetic field distribution. Then the minimum-norm least-squares (MNLS) method, the optimal weighted pseudoinverse method (OWPIM), and the optimal constrained linear inverse method (OCLIM) are selected as the algorithms for inverse computation based on current multipole model innovatively, and the imaging effects of these three inverse methods are compared. Besides, two reconstructing parameters, residual and mean residual, are also discussed, and their trends under MNLS, OWPIM and OCLIM each as a function of SNR are obtained and compared. (general)

  4. Comparison of VLBI radio core and X-ray flux densities of extragalactic radio sources

    Bloom, S.D.; Marscher, A.P.

    1990-01-01

    The Einstein Observatory revealed that most quasars, selected in a variety of ways, are strong x-ray emitters. Radio bright quasars are statistically more luminous in the x-ray than their radio-quiet counterparts. It was also found that the 90 GHz to soft x-ray spectral index has a very small dispersion for sources selected by their strong millimeter emission. This implies a close relationship between compact radio flux density and x-ray emission. Strong correlations have been found between the arcsecond scale flux densities and soft x-ray fluxes. It is suggested that the correlation can be explained if the soft x-rays were produced by the synchrotron self-Compton (SSC) process within the compact radio emitting region. (author)

  5. New vacancy source in ultrahigh-purity aluminium single crystals with a low dislocation density

    Mizuno, Kaoru; Yamamoto, Satoshi [Shimane Univ., Faculty of Science and Engineering, Matsue, Shimane (Japan); Morikawa, Kimihiko [Hokkaido Univ., Institute for Low Temperature Science, Sapporo, Hokkaido (Japan); Kuga, Masanori [Kanazawa Univ., Faculty of Science, Kanazawa, Ishikawa (Japan); Okamoto, Hiroyuki [Kanazawa Univ., Faculty of Medicine, Kanazawa, Ishikawa (Japan); Hashimoto, Eiji [Hiroshima Univ., Hiroshima Synchrotron Radiation Center, Higashi-Hiroshima, Hiroshima (Japan)

    2004-05-01

    The vacancy generation process in ultrahigh-purity aluminum single crystals with a low dislocation density was investigated by synchrotron radiation topography using a white X-ray beam. Some straight lines were observed in the topographys taken after temperature rose to 300degC from room temperature, and they were confirmed to be rows of successive small interstitial-type dislocation loops grown as vacancy sources. It was concluded that the thermal generation mechanism of vacancies in ultrahigh-purity aluminum single crystals with a low dislocation density consists of the following two steps. First, small interstitial loops are heterogeneously formed in the crystal lattice; second, these convert to lengthened loops with the development of screw components and finally grow into rows of dislocation loops emitting vacancies into the lattice. (author)

  6. New vacancy source in ultrahigh-purity aluminium single crystals with a low dislocation density

    Mizuno, Kaoru; Yamamoto, Satoshi; Morikawa, Kimihiko; Kuga, Masanori; Okamoto, Hiroyuki; Hashimoto, Eiji

    2004-01-01

    The vacancy generation process in ultrahigh-purity aluminum single crystals with a low dislocation density was investigated by synchrotron radiation topography using a white X-ray beam. Some straight lines were observed in the topographys taken after temperature rose to 300degC from room temperature, and they were confirmed to be rows of successive small interstitial-type dislocation loops grown as vacancy sources. It was concluded that the thermal generation mechanism of vacancies in ultrahigh-purity aluminum single crystals with a low dislocation density consists of the following two steps. First, small interstitial loops are heterogeneously formed in the crystal lattice; second, these convert to lengthened loops with the development of screw components and finally grow into rows of dislocation loops emitting vacancies into the lattice. (author)

  7. Microwave frequency sweep interferometer for plasma density measurements in ECR ion sources: Design and preliminary results

    Torrisi, Giuseppe [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); University Mediterranea of Reggio Calabria, Reggio Calabria (Italy); Mascali, David; Neri, Lorenzo; Leonardi, Ornella; Celona, Luigi; Castro, Giuseppe; Agnello, Riccardo; Caruso, Antonio; Passarello, Santi; Longhitano, Alberto; Gammino, Santo [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Sorbello, Gino [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); University of Catania, Catania, Italy and INFN-LNS, Catania (Italy); Isernia, Tommaso [University Mediterranea of Reggio Calabria, Reggio Calabria (Italy)

    2016-02-15

    The Electron Cyclotron Resonance Ion Sources (ECRISs) development is strictly related to the availability of new diagnostic tools, as the existing ones are not adequate to such compact machines and to their plasma characteristics. Microwave interferometry is a non-invasive method for plasma diagnostics and represents the best candidate for plasma density measurement in hostile environment. Interferometry in ECRISs is a challenging task mainly due to their compact size. The typical density of ECR plasmas is in the range 10{sup 11}–10{sup 13} cm{sup −3} and it needs a probing beam wavelength of the order of few centimetres, comparable to the chamber radius. The paper describes the design of a microwave interferometer developed at the LNS-INFN laboratories based on the so-called “frequency sweep” method to filter out the multipath contribution in the detected signals. The measurement technique and the preliminary results (calibration) obtained during the experimental tests will be presented.

  8. Earthquake source studies and seismic imaging in Alaska

    Tape, C.; Silwal, V.

    2015-12-01

    Alaska is one of the world's most seismically and tectonically active regions. Its enhanced seismicity, including slab seismicity down to 180 km, provides opportunities (1) to characterize pervasive crustal faulting and slab deformation through the estimation of moment tensors and (2) to image subsurface structures to help understand the tectonic evolution of Alaska. Most previous studies of earthquakes and seismic imaging in Alaska have emphasized earthquake locations and body-wave travel-time tomography. In the past decade, catalogs of seismic moment tensors have been established, while seismic surface waves, active-source data, and potential field data have been used to improve models of seismic structure. We have developed moment tensor catalogs in the regions of two of the largest sedimentary basins in Alaska: Cook Inlet forearc basin, west of Anchorage, and Nenana basin, west of Fairbanks. Our moment tensor solutions near Nenana basin suggest a transtensional tectonic setting, with the basin developing in a stepover of a left-lateral strike-slip fault system. We explore the effects of seismic wave propagation from point-source and finite-source earthquake models by performing three-dimensional wavefield simulations using seismic velocity models that include major sedimentary basins. We will use our catalog of moment tensors within an adjoint-based, iterative inversion to improve the three-dimensional tomographic model of Alaska.

  9. Self-consistent density functional calculation of the image potential at a metal surface

    Jung, J; Alvarellos, J E; Chacon, E; GarcIa-Gonzalez, P

    2007-01-01

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z 0 ), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z 0 , and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description

  10. Fog Density Estimation and Image Defogging Based on Surrogate Modeling for Optical Depth.

    Jiang, Yutong; Sun, Changming; Zhao, Yu; Yang, Li

    2017-05-03

    In order to estimate fog density correctly and to remove fog from foggy images appropriately, a surrogate model for optical depth is presented in this paper. We comprehensively investigate various fog-relevant features and propose a novel feature based on the hue, saturation, and value color space which correlate well with the perception of fog density. We use a surrogate-based method to learn a refined polynomial regression model for optical depth with informative fog-relevant features such as dark-channel, saturation-value, and chroma which are selected on the basis of sensitivity analysis. Based on the obtained accurate surrogate model for optical depth, an effective method for fog density estimation and image defogging is proposed. The effectiveness of our proposed method is verified quantitatively and qualitatively by the experimental results on both synthetic and real-world foggy images.

  11. Self-consistent density functional calculation of the image potential at a metal surface

    Jung, J [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Alvarellos, J E [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Chacon, E [Instituto de Ciencias de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, E-28049 Madrid (Spain); GarcIa-Gonzalez, P [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain)

    2007-07-04

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z{sub 0}), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z{sub 0}, and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description.

  12. An Image Matching Algorithm Integrating Global SRTM and Image Segmentation for Multi-Source Satellite Imagery

    Xiao Ling

    2016-08-01

    Full Text Available This paper presents a novel image matching method for multi-source satellite images, which integrates global Shuttle Radar Topography Mission (SRTM data and image segmentation to achieve robust and numerous correspondences. This method first generates the epipolar lines as a geometric constraint assisted by global SRTM data, after which the seed points are selected and matched. To produce more reliable matching results, a region segmentation-based matching propagation is proposed in this paper, whereby the region segmentations are extracted by image segmentation and are considered to be a spatial constraint. Moreover, a similarity measure integrating Distance, Angle and Normalized Cross-Correlation (DANCC, which considers geometric similarity and radiometric similarity, is introduced to find the optimal correspondences. Experiments using typical satellite images acquired from Resources Satellite-3 (ZY-3, Mapping Satellite-1, SPOT-5 and Google Earth demonstrated that the proposed method is able to produce reliable and accurate matching results.

  13. Visualization and simulation of density driven convection in porous media using magnetic resonance imaging

    Montague, James A.; Pinder, George F.; Gonyea, Jay V.; Hipko, Scott; Watts, Richard

    2018-05-01

    Magnetic resonance imaging is used to observe solute transport in a 40 cm long, 26 cm diameter sand column that contained a central core of low permeability silica surrounded by higher permeability well-sorted sand. Low concentrations (2.9 g/L) of Magnevist, a gadolinium based contrast agent, produce density driven convection within the column when it starts in an unstable state. The unstable state, for this experiment, exists when higher density contrast agent is present above the lower density water. We implement a numerical model in OpenFOAM to reproduce the observed fluid flow and transport from a density difference of 0.3%. The experimental results demonstrate the usefulness of magnetic resonance imaging in observing three-dimensional gravity-driven convective-dispersive transport behaviors in medium scale experiments.

  14. Low energy electron point source microscopy: beyond imaging

    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)

  15. Mapping low- and high-density clouds in astrophysical nebulae by imaging forbidden line emission

    Steiner, J. E.; Menezes, R. B.; Ricci, T. V.; Oliveira, A. S.

    2009-06-01

    Emission line ratios have been essential for determining physical parameters such as gas temperature and density in astrophysical gaseous nebulae. With the advent of panoramic spectroscopic devices, images of regions with emission lines related to these physical parameters can, in principle, also be produced. We show that, with observations from modern instruments, it is possible to transform images taken from density-sensitive forbidden lines into images of emission from high- and low-density clouds by applying a transformation matrix. In order to achieve this, images of the pairs of density-sensitive lines as well as the adjacent continuum have to be observed and combined. We have computed the critical densities for a series of pairs of lines in the infrared, optical, ultraviolet and X-rays bands, and calculated the pair line intensity ratios in the high- and low-density limit using a four- and five-level atom approximation. In order to illustrate the method, we applied it to Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (GMOS-IFU) data of two galactic nuclei. We conclude that this method provides new information of astrophysical interest, especially for mapping low- and high-density clouds; for this reason, we call it `the ld/hd imaging method'. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation on behalf of the Gemini partnership: the National Science Foundation (United States); the Science and Technology Facilities Council (United Kingdom); the National Research Council (Canada), CONICYT (Chile); the Australian Research Council (Australia); Ministério da Ciência e Tecnologia (Brazil) and Secretaria de Ciencia y Tecnologia (Argentina). E-mail: steiner@astro.iag.usp.br

  16. THE Q/U IMAGING EXPERIMENT: POLARIZATION MEASUREMENTS OF RADIO SOURCES AT 43 AND 95 GHz

    Huffenberger, K. M. [Department of Physics, Florida State University, P.O. Box 3064350, Tallahassee, FL 32306-4350 (United States); Araujo, D.; Zwart, J. T. L. [Department of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Bischoff, C.; Buder, I. [Kavli Institute for Cosmological Physics, Department of Physics, Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637 (United States); Chinone, Y.; Hasegawa, M. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Cleary, K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E. California Blvd M/C 249-17, Pasadena, CA 91125 (United States); Kusaka, A. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Monsalve, R. [School of Earth and Space Exploration, Arizona State University, 781 E. Terrace Road, Tempe, AZ 85287 (United States); Næss, S. K. [Department of Astrophysics, University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom); Newburgh, L. B. [Dunlap Institute, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Reeves, R. [CePIA, Departamento de Astronomía, Universidad de Concepción (Chile); Ruud, T. M.; Eriksen, H. K. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Wehus, I. K.; Gaier, T. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Dickinson, C. [Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Gundersen, J. O., E-mail: huffenbe@physics.fsu.edu [Department of Physics, University of Miami, 1320 Campo Sano Drive, Coral Gables, FL 33146 (United States); Collaboration: QUIET Collaboration; and others

    2015-06-10

    We present polarization measurements of extragalactic radio sources observed during the cosmic microwave background polarization survey of the Q/U Imaging Experiment (QUIET), operating at 43 GHz (Q-band) and 95 GHz (W-band). We examine sources selected at 20 GHz from the public, >40 mJy catalog of the Australia Telescope (AT20G) survey. There are ∼480 such sources within QUIET’s four low-foreground survey patches, including the nearby radio galaxies Centaurus A and Pictor A. The median error on our polarized flux density measurements is 30–40 mJy per Stokes parameter. At signal-to-noise ratio > 3 significance, we detect linear polarization for seven sources in Q-band and six in W-band; only 1.3 ± 1.1 detections per frequency band are expected by chance. For sources without a detection of polarized emission, we find that half of the sources have polarization amplitudes below 90 mJy (Q-band) and 106 mJy (W-band), at 95% confidence. Finally, we compare our polarization measurements to intensity and polarization measurements of the same sources from the literature. For the four sources with WMAP and Planck intensity measurements >1 Jy, the polarization fractions are above 1% in both QUIET bands. At high significance, we compute polarization fractions as much as 10%–20% for some sources, but the effects of source variability may cut that level in half for contemporaneous comparisons. Our results indicate that simple models—ones that scale a fixed polarization fraction with frequency—are inadequate to model the behavior of these sources and their contributions to polarization maps.

  17. The climatology of low-latitude ionospheric densities and zonal drifts from IMAGE-FUV.

    Immel, T. J.; Sagawa, E.; Frey, H. U.; Mende, S. B.; Patel, J.

    2004-12-01

    The IMAGE satellite was the first dedicated to magnetospheric imaging, but has also provided numerous images of the nightside ionosphere with its Far-Ultraviolet (FUV) spectrographic imager. Nightside emissions of O I at 135.6-nm originating away from the aurora are due to recombination of ionospheric O+, and vary in intensity with (O+)2. IMAGE-FUV, operating in a highly elliptical orbit with apogee at middle latitudes and >7 Re altitude, measures this emission globally with 100-km resolution. During each 14.5 hour orbit, IMAGE-FUV is able to monitor nightside ionospheric densities for up to 6-7 hours. Hundreds of low-latitude ionospheric bubbles, their development and drift speed, and a variety of other dynamical variations in brightness and morphology of the equatorial anomalies have been observed during this mission. Furthermore, the average global distribution of low-latitude ionospheric plasma densities can be determined in 3 days. Imaging data collected from February through June of 2002 are used to compile a dataset containing a variety of parameters (e.g., latitude and brightness of peak plasma density, zonal bubble drift speed) which can be drawn from for climatological studies. Recent results indicate that the average ground speed of low-latitude zonal plasma drifts vary with longitude by up to 50%, and that a periodic variation in ionospheric densities with longitude suggests the influence of a lower-thermospheric non-migrating tide with wave number = 4 on ionospheric densities. An excellent correlation between zonal drift speed and the magnetic storm index Dst is also found.

  18. Experimental atheromatous plaque imaging with 99mTc labelled low density lipoproteins in rabbit

    Wang Quanshi; Chen Yu; Wu Chunshan; Zhang Yijin; Liu Dexuan

    1996-01-01

    Atheromatous plaque imaging with 99m Tc labeled low density lipoproteins ( 99m Tc-LDL) were evaluated in rabbits for its clinical prospect. The 99m Tc-LDL atheromatous plaque imaging were performed in 9 rabbit models of atherosclerosis and 4 controls. The imagings were compared with autoradiographic and pathological results. The rabbit models of atherosclerosis by high cholesterol and high fat diet were successful in 100%. The atheromatous plaques well visualized in 8 of 9 rabbit models 24 hours after injection. The site and density of radioactive accumulation was closely correlated in autoradiography also. There was no radioactive spot in 4 controls. 99m Tc-LDL imaging may have a significant value for the diagnosis of atherosclerosis

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

    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

  20. Self-Calibrating Wave-Encoded Variable-Density Single-Shot Fast Spin Echo Imaging.

    Chen, Feiyu; Taviani, Valentina; Tamir, Jonathan I; Cheng, Joseph Y; Zhang, Tao; Song, Qiong; Hargreaves, Brian A; Pauly, John M; Vasanawala, Shreyas S

    2018-04-01

    It is highly desirable in clinical abdominal MR scans to accelerate single-shot fast spin echo (SSFSE) imaging and reduce blurring due to T 2 decay and partial-Fourier acquisition. To develop and investigate the clinical feasibility of wave-encoded variable-density SSFSE imaging for improved image quality and scan time reduction. Prospective controlled clinical trial. With Institutional Review Board approval and informed consent, the proposed method was assessed on 20 consecutive adult patients (10 male, 10 female, range, 24-84 years). A wave-encoded variable-density SSFSE sequence was developed for clinical 3.0T abdominal scans to enable high acceleration (3.5×) with full-Fourier acquisitions by: 1) introducing wave encoding with self-refocusing gradient waveforms to improve acquisition efficiency; 2) developing self-calibrated estimation of wave-encoding point-spread function and coil sensitivity to improve motion robustness; and 3) incorporating a parallel imaging and compressed sensing reconstruction to reconstruct highly accelerated datasets. Image quality was compared pairwise with standard Cartesian acquisition independently and blindly by two radiologists on a scale from -2 to 2 for noise, contrast, confidence, sharpness, and artifacts. The average ratio of scan time between these two approaches was also compared. A Wilcoxon signed-rank tests with a P value under 0.05 considered statistically significant. Wave-encoded variable-density SSFSE significantly reduced the perceived noise level and improved the sharpness of the abdominal wall and the kidneys compared with standard acquisition (mean scores 0.8, 1.2, and 0.8, respectively, P variable-density sampling SSFSE achieves improved image quality with clinically relevant echo time and reduced scan time, thus providing a fast and robust approach for clinical SSFSE imaging. 1 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2018;47:954-966. © 2017 International Society for Magnetic Resonance in Medicine.

  1. Restriction Spectrum Imaging As a Potential Measure of Cortical Neurite Density in Autism

    Carper, Ruth A.; Treiber, Jeffrey M.; White, Nathan S.; Kohli, Jiwandeep S.; M?ller, Ralph-Axel

    2017-01-01

    Autism postmortem studies have shown various cytoarchitectural anomalies in cortical and limbic areas including increased cell packing density, laminar disorganization, and narrowed minicolumns. However, there is little evidence on dendritic and axonal organization in ASD. Recent imaging techniques have the potential for non-invasive, in vivo studies of small-scale structure in the human brain, including gray matter. Here, Restriction Spectrum Imaging (RSI), a multi-shell diffusion-weighted i...

  2. Fast in-database cross-matching of high-cadence, high-density source lists with an up-to-date sky model

    Scheers, B.; Bloemen, S.; Mühleisen, H.; Schellart, P.; van Elteren, A.; Kersten, M.; Groot, P. J.

    2018-04-01

    Coming high-cadence wide-field optical telescopes will image hundreds of thousands of sources per minute. Besides inspecting the near real-time data streams for transient and variability events, the accumulated data archive is a wealthy laboratory for making complementary scientific discoveries. The goal of this work is to optimise column-oriented database techniques to enable the construction of a full-source and light-curve database for large-scale surveys, that is accessible by the astronomical community. We adopted LOFAR's Transients Pipeline as the baseline and modified it to enable the processing of optical images that have much higher source densities. The pipeline adds new source lists to the archive database, while cross-matching them with the known cataloguedsources in order to build a full light-curve archive. We investigated several techniques of indexing and partitioning the largest tables, allowing for faster positional source look-ups in the cross matching algorithms. We monitored all query run times in long-term pipeline runs where we processed a subset of IPHAS data that have image source density peaks over 170,000 per field of view (500,000 deg-2). Our analysis demonstrates that horizontal table partitions of declination widths of one-degree control the query run times. Usage of an index strategy where the partitions are densely sorted according to source declination yields another improvement. Most queries run in sublinear time and a few (< 20%) run in linear time, because of dependencies on input source-list and result-set size. We observed that for this logical database partitioning schema the limiting cadence the pipeline achieved with processing IPHAS data is 25 s.

  3. Endoscopic hyperspectral imaging: light guide optimization for spectral light source

    Browning, Craig M.; Mayes, Samuel; Rich, Thomas C.; Leavesley, Silas J.

    2018-02-01

    Hyperspectral imaging (HSI) is a technology used in remote sensing, food processing and documentation recovery. Recently, this approach has been applied in the medical field to spectrally interrogate regions of interest within respective substrates. In spectral imaging, a two (spatial) dimensional image is collected, at many different (spectral) wavelengths, to sample spectral signatures from different regions and/or components within a sample. Here, we report on the use of hyperspectral imaging for endoscopic applications. Colorectal cancer is the 3rd leading cancer for incidences and deaths in the US. One factor of severity is the miss rate of precancerous/flat lesions ( 65% accuracy). Integrating HSI into colonoscopy procedures could minimize misdiagnosis and unnecessary resections. We have previously reported a working prototype light source with 16 high-powered light emitting diodes (LEDs) capable of high speed cycling and imaging. In recent testing, we have found our current prototype is limited by transmission loss ( 99%) through the multi-furcated solid light guide (lightpipe) and the desired framerate (20-30 fps) could not be achieved. Here, we report on a series of experimental and modeling studies to better optimize the lightpipe and the spectral endoscopy system as a whole. The lightpipe was experimentally evaluated using an integrating sphere and spectrometer (Ocean Optics). Modeling the lightpipe was performed using Monte Carlo optical ray tracing in TracePro (Lambda Research Corp.). Results of these optimization studies will aid in manufacturing a revised prototype with the newly designed light guide and increased sensitivity. Once the desired optical output (5-10 mW) is achieved then the HIS endoscope system will be able to be implemented without adding onto the procedure time.

  4. DEMARCATE: Density-based magnetic resonance image clustering for assessing tumor heterogeneity in cancer.

    Saha, Abhijoy; Banerjee, Sayantan; Kurtek, Sebastian; Narang, Shivali; Lee, Joonsang; Rao, Ganesh; Martinez, Juan; Bharath, Karthik; Rao, Arvind U K; Baladandayuthapani, Veerabhadran

    2016-01-01

    Tumor heterogeneity is a crucial area of cancer research wherein inter- and intra-tumor differences are investigated to assess and monitor disease development and progression, especially in cancer. The proliferation of imaging and linked genomic data has enabled us to evaluate tumor heterogeneity on multiple levels. In this work, we examine magnetic resonance imaging (MRI) in patients with brain cancer to assess image-based tumor heterogeneity. Standard approaches to this problem use scalar summary measures (e.g., intensity-based histogram statistics) that do not adequately capture the complete and finer scale information in the voxel-level data. In this paper, we introduce a novel technique, DEMARCATE (DEnsity-based MAgnetic Resonance image Clustering for Assessing Tumor hEterogeneity) to explore the entire tumor heterogeneity density profiles (THDPs) obtained from the full tumor voxel space. THDPs are smoothed representations of the probability density function of the tumor images. We develop tools for analyzing such objects under the Fisher-Rao Riemannian framework that allows us to construct metrics for THDP comparisons across patients, which can be used in conjunction with standard clustering approaches. Our analyses of The Cancer Genome Atlas (TCGA) based Glioblastoma dataset reveal two significant clusters of patients with marked differences in tumor morphology, genomic characteristics and prognostic clinical outcomes. In addition, we see enrichment of image-based clusters with known molecular subtypes of glioblastoma multiforme, which further validates our representation of tumor heterogeneity and subsequent clustering techniques.

  5. Detection of Point Sources on Two-Dimensional Images Based on Peaks

    R. B. Barreiro

    2005-09-01

    Full Text Available This paper considers the detection of point sources in two-dimensional astronomical images. The detection scheme we propose is based on peak statistics. We discuss the example of the detection of far galaxies in cosmic microwave background experiments throughout the paper, although the method we present is totally general and can be used in many other fields of data analysis. We consider sources with a Gaussian profile—that is, a fair approximation of the profile of a point source convolved with the detector beam in microwave experiments—on a background modeled by a homogeneous and isotropic Gaussian random field characterized by a scale-free power spectrum. Point sources are enhanced with respect to the background by means of linear filters. After filtering, we identify local maxima and apply our detection scheme, a Neyman-Pearson detector that defines our region of acceptance based on the a priori pdf of the sources and the ratio of number densities. We study the different performances of some linear filters that have been used in this context in the literature: the Mexican hat wavelet, the matched filter, and the scale-adaptive filter. We consider as well an extension to two dimensions of the biparametric scale-adaptive filter (BSAF. The BSAF depends on two parameters which are determined by maximizing the number density of real detections while fixing the number density of spurious detections. For our detection criterion the BSAF outperforms the other filters in the interesting case of white noise.

  6. Model-based estimation of breast percent density in raw and processed full-field digital mammography images from image-acquisition physics and patient-image characteristics

    Keller, Brad M.; Nathan, Diane L.; Conant, Emily F.; Kontos, Despina

    2012-03-01

    Breast percent density (PD%), as measured mammographically, is one of the strongest known risk factors for breast cancer. While the majority of studies to date have focused on PD% assessment from digitized film mammograms, digital mammography (DM) is becoming increasingly common, and allows for direct PD% assessment at the time of imaging. This work investigates the accuracy of a generalized linear model-based (GLM) estimation of PD% from raw and postprocessed digital mammograms, utilizing image acquisition physics, patient characteristics and gray-level intensity features of the specific image. The model is trained in a leave-one-woman-out fashion on a series of 81 cases for which bilateral, mediolateral-oblique DM images were available in both raw and post-processed format. Baseline continuous and categorical density estimates were provided by a trained breast-imaging radiologist. Regression analysis is performed and Pearson's correlation, r, and Cohen's kappa, κ, are computed. The GLM PD% estimation model performed well on both processed (r=0.89, p<0.001) and raw (r=0.75, p<0.001) images. Model agreement with radiologist assigned density categories was also high for processed (κ=0.79, p<0.001) and raw (κ=0.76, p<0.001) images. Model-based prediction of breast PD% could allow for a reproducible estimation of breast density, providing a rapid risk assessment tool for clinical practice.

  7. An open source toolkit for medical imaging de-identification

    Rodriguez Gonzalez, David; Carpenter, Trevor; Wardlaw, Joanna; Hemert, Jano I. van

    2010-01-01

    Medical imaging acquired for clinical purposes can have several legitimate secondary uses in research projects and teaching libraries. No commonly accepted solution for anonymising these images exists because the amount of personal data that should be preserved varies case by case. Our objective is to provide a flexible mechanism for anonymising Digital Imaging and Communications in Medicine (DICOM) data that meets the requirements for deployment in multicentre trials. We reviewed our current de-identification practices and defined the relevant use cases to extract the requirements for the de-identification process. We then used these requirements in the design and implementation of the toolkit. Finally, we tested the toolkit taking as a reference those requirements, including a multicentre deployment. The toolkit successfully anonymised DICOM data from various sources. Furthermore, it was shown that it could forward anonymous data to remote destinations, remove burned-in annotations, and add tracking information to the header. The toolkit also implements the DICOM standard confidentiality mechanism. A DICOM de-identification toolkit that facilitates the enforcement of privacy policies was developed. It is highly extensible, provides the necessary flexibility to account for different de-identification requirements and has a low adoption barrier for new users. (orig.)

  8. Laser plasmas as x-ray sources for lithographic imaging of submicron structures

    Bijkerk, F.; van Dorssen, G.E.; van der Wiel, M.J.

    1988-01-01

    Laser radiation can be used efficiently to generate x-rays for lithographic imaging of submicron patterns, e.g., for VLSI device fabrication. Due to their short wavelength and high average power, excimer lasers show much potential for this application. Results are presented of scaling studies for high repetition rate excimer laser application, using the frequency doubled output of a low repetition rate Nd:YAG/Glass laser. Spectral and spatial characteristics of x-ray emission of the laser plasma are shown. The power density in the laser focus was 3 x 10 12 W/cm 2 . With this source Si x-ray masks with submicron Au absorber profiles are imaged into high sensitivity x-ray photoresist. For the exposures 80 laser shots sufficed to yield high quality submicron structures. Extrapolation of the results to a high power excimer laser reduces the exposure time of the photoresists to several seconds, enabling a wafer throughput at an industrial level

  9. System and method for magnetic current density imaging at ultra low magnetic fields

    Espy, Michelle A.; George, John Stevens; Kraus, Robert Henry; Magnelind, Per; Matlashov, Andrei Nikolaevich; Tucker, Don; Turovets, Sergei; Volegov, Petr Lvovich

    2016-02-09

    Preferred systems can include an electrical impedance tomography apparatus electrically connectable to an object; an ultra low field magnetic resonance imaging apparatus including a plurality of field directions and disposable about the object; a controller connected to the ultra low field magnetic resonance imaging apparatus and configured to implement a sequencing of one or more ultra low magnetic fields substantially along one or more of the plurality of field directions; and a display connected to the controller, and wherein the controller is further configured to reconstruct a displayable image of an electrical current density in the object. Preferred methods, apparatuses, and computer program products are also disclosed.

  10. Determination of vehicle density from traffic images at day and nighttime

    Mehrübeoğlu, Mehrübe; McLauchlan, Lifford

    2007-02-01

    In this paper we extend our previous work to address vehicle differentiation in traffic density computations1. The main goal of this work is to create vehicle density history for given roads under different weather or light conditions and at different times of the day. Vehicle differentiation is important to account for connected or otherwise long vehicles, such as trucks or tankers, which lead to over-counting with the original algorithm. Average vehicle size in pixels, given the magnification within the field of view for a particular camera, is used to separate regular cars and long vehicles. A separate algorithm and procedure have been developed to determine traffic density after dark when the vehicle headlights are turned on. Nighttime vehicle recognition utilizes blob analysis based on head/taillight images. The high intensity of vehicle lights are identified in binary images for nighttime vehicle detection. The stationary traffic image frames are downloaded from the internet as they are updated. The procedures are implemented in MATLAB. The results of both nighttime traffic density and daytime long vehicle identification algorithms are described in this paper. The determination of nighttime traffic density, and identification of long vehicles at daytime are improvements over the original work1.

  11. Particle image velocimetry measurements and numerical modeling of a saline density current

    Gerber, G

    2011-03-01

    Full Text Available Particle image velocimetry scalar measurements were carried out on the body of a stably stratified density current with an inlet Reynolds number of 2,300 and bulk Richardson number of 0.1. These measurements allowed the mass and momentum transport...

  12. Imaging Management of Breast Density, a Controversial Risk Factor for Breast Cancer.

    Falcon, Shannon; Williams, Angela; Weinfurtner, Jared; Drukteinis, Jennifer S

    2017-04-01

    Breast density is well recognized as an independent risk factor for the development of breast cancer. However, the magnitude of risk is controversial. As the public becomes increasingly aware of breast density as a risk factor, legislation and notification laws in relation to breast density have become common throughout the United States. Awareness of breast density as a risk factor for breast cancer presents new challenges for the clinician in the approach to the management and screening of women with dense breasts. The evidence and controversy surrounding breast density as a risk factor for the development of breast cancer are discussed. Common supplemental screening modalities for breast cancer are also discussed, including tomosynthesis, ultrasonography, and magnetic resonance imaging. A management strategy for screening women with dense breasts is also presented. The American College of Radiology recognizes breast density as a controversial risk factor for breast cancer, whereas the American Congress of Obstetricians and Gynecologists recognizes breast density as a modest risk factor. Neither organization recommends the routine use of supplemental screening in women with dense breasts without considering additional patient-related risk factors. Breast density is a poorly understood and controversial risk factor for the development of breast cancer. Mammography is a screening modality proven to reduce breast cancer-related mortality rates and is the single most appropriate tool for population-based screening. Use of supplemental screening modalities should be tailored to individual risk assessment.

  13. Characterization of laser-produced plasma density profiles using grid image refractometry

    Craxton, R.S.; Turner, F.S.; Hoefen, R.; Darrow, C.; Gabl, E.F.; Busch, G.E.

    1993-01-01

    Grid image refractometry (GIR) is proposed as a technique for determining the two-dimensional density profiles of long scale-length laser-produced plasmas. Its distinctive feature is that an optical probe beam is broken up into ''rays'' by being passed through a grid before traversing the plasma. The refraction angles of the rays are measured by imaging the plasma at two or more object planes and are integrated to yield the phase front. For cylindrically symmetric plasmas the density profile is then determined using Abel inversion. The feasibility of GIR is illustrated by an experiment in which a thick CH target was irradiated with ∼100 J of 527 nm radiation and diagnosed with a 20 ps, 263 nm probe. The resulting density profile is substantially larger than any that have previously been reported using interferometry and compares quite closely with hydrodynamic simulations

  14. Extracting functional components of neural dynamics with Independent Component Analysis and inverse Current Source Density.

    Lęski, Szymon; Kublik, Ewa; Swiejkowski, Daniel A; Wróbel, Andrzej; Wójcik, Daniel K

    2010-12-01

    Local field potentials have good temporal resolution but are blurred due to the slow spatial decay of the electric field. For simultaneous recordings on regular grids one can reconstruct efficiently the current sources (CSD) using the inverse Current Source Density method (iCSD). It is possible to decompose the resultant spatiotemporal information about the current dynamics into functional components using Independent Component Analysis (ICA). We show on test data modeling recordings of evoked potentials on a grid of 4 × 5 × 7 points that meaningful results are obtained with spatial ICA decomposition of reconstructed CSD. The components obtained through decomposition of CSD are better defined and allow easier physiological interpretation than the results of similar analysis of corresponding evoked potentials in the thalamus. We show that spatiotemporal ICA decompositions can perform better for certain types of sources but it does not seem to be the case for the experimental data studied. Having found the appropriate approach to decomposing neural dynamics into functional components we use the technique to study the somatosensory evoked potentials recorded on a grid spanning a large part of the forebrain. We discuss two example components associated with the first waves of activation of the somatosensory thalamus. We show that the proposed method brings up new, more detailed information on the time and spatial location of specific activity conveyed through various parts of the somatosensory thalamus in the rat.

  15. Simultaneous Microwave Imaging System for Density and Temperature Fluctuation Measurements on TEXTOR

    Park, H.; Mazzucato, E.; Munsat, T.; 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

    Diagnostic systems for fluctuation measurements in plasmas have, of necessity, evolved from simple 1-D systems to multi-dimensional systems due to the complexity of the MHD and turbulence physics of plasmas illustrated by advanced numerical simulations. Using the recent significant advancements in millimeter wave imaging technology, Microwave Imaging Reflectometry (MIR) and Electron Cyclotron Emission Imaging (ECEI), simultaneously measuring density and temperature fluctuations, are developed for TEXTOR. The MIR system was installed on TEXTOR and the first experiment was performed in September, 2003. Subsequent MIR campaigns have yielded poloidally resolved spectra and assessments of poloidal velocity. The new 2-D ECE Imaging system (with a total of 128 channels), installed on TEXTOR in December, 2003, successfully captured a true 2-D images of Te fluctuations of m=1 oscillation (''sawteeth'') near the q ∼ 1 surface for the first time

  16. Noncontrast cardiac computed tomography image-based vertebral bone mineral density: the Multi-Ethnic Study of Atherosclerosis (MESA).

    Li, Dong; Mao, Song Shou; Khazai, Bahram; Hyder, Joseph A; Allison, Matthew; McClelland, Robyn; de Boer, Ian; Carr, J Jeffrey; Criqui, Michael H; Gao, Yanlin; Budoff, Matthew J

    2013-05-01

    Cardiac computer tomography (CT) image-based vertebral bone mineral density (BMD) assessment and the influence of cardiovascular disease risk factors on BMD have not been systematically evaluated, especially in a community-based, multiethnic population. A cross-sectional study design is used to determine if cardiac CT image is a reliable source to assess vertebral BMD, and a total of 2028 CT images were obtained from the Multi-Ethnic Study of Atherosclerosis, a large, diverse US cohort of adults 45 to 84 years of age. Cardiac CT image allows the rapid assessment of vertebral BMD and related fractures. The mean BMD was significantly higher in men compared with women for thoracic vertebrae (143.2 ± 41.2 vs 138.7 ± 42.7 mg/cm³, respectively, P = .014), as well as for lumbar vertebrae (125.0 ± 37.9 vs 117.2 ± 39.4 mg/cm³, respectively, P images to garner and assess vertebral BMD is a feasible and reliable method. Cardiac CT has the additional advantages of evaluate vertebral bone health while assessing cardiovascular disease risk with no extra cost or radiation exposure. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

  17. Methodology for attainment of density and effective atomic number through dual energy technique using microtomographic images

    Alves, H.; Lima, I.; Lopes, R.T.

    2014-01-01

    Dual energy technique for computerized microtomography shows itself as a promising method for identification of mineralogy on geological samples of heterogeneous composition. It can also assist with differentiating very similar objects regarding the attenuation coefficient, which are usually not separable during image processing and analysis of microtomographic data. Therefore, the development of a feasible and applicable methodology of dual energy in the analysis of microtomographic images was sought. - Highlights: • Dual energy technique is promising for identification of distribution of minerals. • A feasible methodology of dual energy in analysis of tomographic images was sought. • The dual energy technique is efficient for density and atomic number identification. • Simulation showed that the proposed methodology agrees with theoretical data. • Nondestructive characterization of distribution of density and chemical composition

  18. Technical factors influencing cone packing density estimates in adaptive optics flood illuminated retinal images.

    Marco Lombardo

    Full Text Available PURPOSE: To investigate the influence of various technical factors on the variation of cone packing density estimates in adaptive optics flood illuminated retinal images. METHODS: Adaptive optics images of the photoreceptor mosaic were obtained in fifteen healthy subjects. The cone density and Voronoi diagrams were assessed in sampling windows of 320×320 µm, 160×160 µm and 64×64 µm at 1.5 degree temporal and superior eccentricity from the preferred locus of fixation (PRL. The technical factors that have been analyzed included the sampling window size, the corrected retinal magnification factor (RMFcorr, the conversion from radial to linear distance from the PRL, the displacement between the PRL and foveal center and the manual checking of cone identification algorithm. Bland-Altman analysis was used to assess the agreement between cone density estimated within the different sampling window conditions. RESULTS: The cone density declined with decreasing sampling area and data between areas of different size showed low agreement. A high agreement was found between sampling areas of the same size when comparing density calculated with or without using individual RMFcorr. The agreement between cone density measured at radial and linear distances from the PRL and between data referred to the PRL or the foveal center was moderate. The percentage of Voronoi tiles with hexagonal packing arrangement was comparable between sampling areas of different size. The boundary effect, presence of any retinal vessels, and the manual selection of cones missed by the automated identification algorithm were identified as the factors influencing variation of cone packing arrangements in Voronoi diagrams. CONCLUSIONS: The sampling window size is the main technical factor that influences variation of cone density. Clear identification of each cone in the image and the use of a large buffer zone are necessary to minimize factors influencing variation of Voronoi

  19. Application of neurite orientation dispersion and density imaging (NODDI) to a tau pathology model of Alzheimer's disease.

    Colgan, N

    2015-10-23

    Increased hyperphosphorylated tau and the formation of intracellular neurofibrillary tangles are associated with the loss of neurons and cognitive decline in Alzheimer\\'s disease, and related neurodegenerative conditions. We applied two diffusion models, diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI), to in vivo diffusion magnetic resonance images (dMRI) of a mouse model of human tauopathy (rTg4510) at 8.5months of age. In grey matter regions with the highest degree of tau burden, microstructural indices provided by both NODDI and DTI discriminated the rTg4510 (TG) animals from wild type (WT) controls; however only the neurite density index (NDI) (the volume fraction that comprises axons or dendrites) from the NODDI model correlated with the histological measurements of the levels of hyperphosphorylated tau protein. Reductions in diffusion directionality were observed when implementing both models in the white matter region of the corpus callosum, with lower fractional anisotropy (DTI) and higher orientation dispersion (NODDI) observed in the TG animals. In comparison to DTI, histological measures of tau pathology were more closely correlated with NODDI parameters in this region. This in vivo dMRI study demonstrates that NODDI identifies potential tissue sources contributing to DTI indices and NODDI may provide greater specificity to pathology in Alzheimer\\'s disease.

  20. Breast density quantification using magnetic resonance imaging (MRI) with bias field correction: a postmortem study.

    Ding, Huanjun; Johnson, Travis; Lin, Muqing; Le, Huy Q; Ducote, Justin L; Su, Min-Ying; Molloi, Sabee

    2013-12-01

    Quantification of breast density based on three-dimensional breast MRI may provide useful information for the early detection of breast cancer. However, the field inhomogeneity can severely challenge the computerized image segmentation process. In this work, the effect of the bias field in breast density quantification has been investigated with a postmortem study. T1-weighted images of 20 pairs of postmortem breasts were acquired on a 1.5 T breast MRI scanner. Two computer-assisted algorithms were used to quantify the volumetric breast density. First, standard fuzzy c-means (FCM) clustering was used on raw images with the bias field present. Then, the coherent local intensity clustering (CLIC) method estimated and corrected the bias field during the iterative tissue segmentation process. Finally, FCM clustering was performed on the bias-field-corrected images produced by CLIC method. The left-right correlation for breasts in the same pair was studied for both segmentation algorithms to evaluate the precision of the tissue classification. Finally, the breast densities measured with the three methods were compared to the gold standard tissue compositions obtained from chemical analysis. The linear correlation coefficient, Pearson's r, was used to evaluate the two image segmentation algorithms and the effect of bias field. The CLIC method successfully corrected the intensity inhomogeneity induced by the bias field. In left-right comparisons, the CLIC method significantly improved the slope and the correlation coefficient of the linear fitting for the glandular volume estimation. The left-right breast density correlation was also increased from 0.93 to 0.98. When compared with the percent fibroglandular volume (%FGV) from chemical analysis, results after bias field correction from both the CLIC the FCM algorithms showed improved linear correlation. As a result, the Pearson's r increased from 0.86 to 0.92 with the bias field correction. The investigated CLIC method

  1. Breast density quantification using magnetic resonance imaging (MRI) with bias field correction: A postmortem study

    Ding, Huanjun; Johnson, Travis; Lin, Muqing; Le, Huy Q.; Ducote, Justin L.; Su, Min-Ying; Molloi, Sabee

    2013-01-01

    Purpose: Quantification of breast density based on three-dimensional breast MRI may provide useful information for the early detection of breast cancer. However, the field inhomogeneity can severely challenge the computerized image segmentation process. In this work, the effect of the bias field in breast density quantification has been investigated with a postmortem study. Methods: T1-weighted images of 20 pairs of postmortem breasts were acquired on a 1.5 T breast MRI scanner. Two computer-assisted algorithms were used to quantify the volumetric breast density. First, standard fuzzy c-means (FCM) clustering was used on raw images with the bias field present. Then, the coherent local intensity clustering (CLIC) method estimated and corrected the bias field during the iterative tissue segmentation process. Finally, FCM clustering was performed on the bias-field-corrected images produced by CLIC method. The left–right correlation for breasts in the same pair was studied for both segmentation algorithms to evaluate the precision of the tissue classification. Finally, the breast densities measured with the three methods were compared to the gold standard tissue compositions obtained from chemical analysis. The linear correlation coefficient, Pearson'sr, was used to evaluate the two image segmentation algorithms and the effect of bias field. Results: The CLIC method successfully corrected the intensity inhomogeneity induced by the bias field. In left–right comparisons, the CLIC method significantly improved the slope and the correlation coefficient of the linear fitting for the glandular volume estimation. The left–right breast density correlation was also increased from 0.93 to 0.98. When compared with the percent fibroglandular volume (%FGV) from chemical analysis, results after bias field correction from both the CLIC the FCM algorithms showed improved linear correlation. As a result, the Pearson'sr increased from 0.86 to 0.92 with the bias field correction

  2. Device for forming the image of a radiation source

    Tosswill, C.H.

    1980-01-01

    An improvement can be made to the space resolution of systems providing the image of a radiation source by means of a slit collimator. In order to do so, a lateral movement of the collimator (with its detectors) is superimposed on the movement of the collimator, in a transversal direction in relation to the transmission direction through the collimator as well as in relation to the walls defining the slits. The total amplitude of the lateral movement is at least equal to the distance between centres of a slit and the following one. In the near field operating system, the lateral movement is a rectilinear movement perpendicular to the walls of the slits. In the distance field operating systems, it is an angular movement about an axis perpendicular to the direction of transmission through the slits [fr

  3. Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages.

    Jones, Christopher P; Brenner, Ceri M; Stitt, Camilla A; Armstrong, Chris; Rusby, Dean R; Mirfayzi, Seyed R; Wilson, Lucy A; Alejo, Aarón; Ahmed, Hamad; Allott, Ric; Butler, Nicholas M H; Clarke, Robert J; Haddock, David; Hernandez-Gomez, Cristina; Higginson, Adam; Murphy, Christopher; Notley, Margaret; Paraskevoulakos, Charilaos; Jowsey, John; McKenna, Paul; Neely, David; Kar, Satya; Scott, Thomas B

    2016-11-15

    A small scale sample nuclear waste package, consisting of a 28mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500keV), with a source size of <0.5mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30cm(2) scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned. Copyright © 2016. Published by Elsevier B.V.

  4. Three-dimensional display of magnetic source imaging (MSI)

    Morioka, Takato; Yamamoto, Tomoya; Nishio, Shunji; Hasuo, Kanehiro; Fujii, Kiyotaka; Fukui, Masashi; Nitta, Koichi.

    1995-01-01

    Magnetic source imaging (MSI) is a relatively new, noninvasive technique for defining the relationship between brain structure and function of individual patients, and to establish comparisons from one patient to another. This is achieved by combining detailed neurophysiological data derived via magnetoencephalography (MEG) with neuroimaging data such as computed tomographic scan and magnetic resonance imaging (MRI). The noninvasive presurgical mapping of cortical functional somatosensory activity and the direct mapping of epilepsy-associated activity are among the neurosurgical uses that are emerging for MSI. Although the procedure provides clinically useful data, there are still limitations to two-dimensional MSI. We employ three-dimensional (3-D) MSI, superimposing MSI localizations on 3-D volumetric reconstruction of MRI. 3-D MSI enhances the visualization of the entire sensory homunculus and clearly demonstrates the spatial relationship with structural lesions. The functional localization of the epileptic focus in spatial relation to the lesion provides important clues for preoperative planning and on the epileptogenicity of the lesion. 3-D MSI improves localization of the sensory cortex and generator areas of epileptic activity. (author)

  5. Hydrogeophysical imaging of deposit heterogeneity and groundwater chemistry changes during DNAPL source zone bioremediation.

    Chambers, J E; Wilkinson, P B; Wealthall, G P; Loke, M H; Dearden, R; Wilson, R; Allen, D; Ogilvy, R D

    2010-10-21

    Robust characterization and monitoring of dense nonaqueous phase liquid (DNAPL) source zones is essential for designing effective remediation strategies, and for assessing the efficacy of treatment. In this study high-resolution cross-hole electrical resistivity tomography (ERT) was evaluated as a means of monitoring a field-scale in-situ bioremediation experiment, in which emulsified vegetable oil (EVO) electron donor was injected into a trichloroethene source zone. Baseline ERT scans delineated the geometry of the interface between the contaminated alluvial aquifer and the underlying mudstone bedrock, and also the extent of drilling-induced physical heterogeneity. Time-lapse ERT images revealed major preferential flow pathways in the source and plume zones, which were corroborated by multiple lines of evidence, including geochemical monitoring and hydraulic testing using high density multilevel sampler arrays within the geophysical imaging planes. These pathways were shown to control the spatial distribution of the injected EVO, and a bicarbonate buffer introduced into the cell for pH control. Resistivity signatures were observed within the preferential flow pathways that were consistent with elevated chloride levels, providing tentative evidence from ERT of the biodegradation of chlorinated solvents. Copyright © 2010 S. Yamamoto. Published by Elsevier B.V. All rights reserved.

  6. Imaging multipole gravity anomaly sources by 3D probability tomography

    Alaia, Raffaele; Patella, Domenico; Mauriello, Paolo

    2009-01-01

    We present a generalized theory of the probability tomography applied to the gravity method, assuming that any Bouguer anomaly data set can be caused by a discrete number of monopoles, dipoles, quadrupoles and octopoles. These elementary sources are used to characterize, in an as detailed as possible way and without any a priori assumption, the shape and position of the most probable minimum structure of the gravity sources compatible with the observed data set, by picking out the location of their centres and peculiar points of their boundaries related to faces, edges and vertices. A few synthetic examples using simple geometries are discussed in order to demonstrate the notably enhanced resolution power of the new approach, compared with a previous formulation that used only monopoles and dipoles. A field example related to a gravity survey carried out in the volcanic area of Mount Etna (Sicily, Italy) is presented, aimed at imaging the geometry of the minimum gravity structure down to 8 km of depth bsl

  7. Matrix kernels for MEG and EEG source localization and imaging

    Mosher, J.C.; Lewis, P.S.; Leahy, R.M.

    1994-01-01

    The most widely used model for electroencephalography (EEG) and magnetoencephalography (MEG) assumes a quasi-static approximation of Maxwell's equations and a piecewise homogeneous conductor model. Both models contain an incremental field element that linearly relates an incremental source element (current dipole) to the field or voltage at a distant point. The explicit form of the field element is dependent on the head modeling assumptions and sensor configuration. Proper characterization of this incremental element is crucial to the inverse problem. The field element can be partitioned into the product of a vector dependent on sensor characteristics and a matrix kernel dependent only on head modeling assumptions. We present here the matrix kernels for the general boundary element model (BEM) and for MEG spherical models. We show how these kernels are easily interchanged in a linear algebraic framework that includes sensor specifics such as orientation and gradiometer configuration. We then describe how this kernel is easily applied to ''gain'' or ''transfer'' matrices used in multiple dipole and source imaging models

  8. Simulation Study of an Extended Density DC Glow Toroidal Plasma Source

    Granda-Gutierrez, E. E.; Piedad-Beneitez, A. de la; Lopez-Callejas, R.; Godoy-Cabrera, O. G.; Benitez-Read, J. S.; Pacheco-Sotelo, J. O.; Pena-Eguiluz, R.; Mercado-Cabrera, A.; Valencia A, R.; Barocio, S. R.

    2006-01-01

    Conventional wisdom assigns the DC glow discharge regime to plasma currents below ∼500 mA values, beyond which the discharge falls into the anomalous glow and the turbulent arc regimes. However, we have found evidence that, during toroidal discharges, this barrier can be ostensibly extended up to 800 mA. Thus, a computer simulation has been applied to the evolution of the main electrical characteristics of such a glow discharge plasma in a toroidal vessel in order to design and construct a respective voltage/current controlled source. This should be able to generate a DC plasma in the glow regime with which currents in the range 10-3-100 A can be experimented and 109-1010 cm-3 plasma densities can be achieved to PIII optimization purposes. The plasma is modelled as a voltage-controlled current source able to be turned on whenever the breakdown voltage is reached across the gap between the anode and the vessel wall. The simulation outcome fits well our experimental measurements showing that the plasma current obeys power laws that are dependent on the power current and other control variables such as the gas pressure

  9. High Density Aerial Image Matching: State-Of and Future Prospects

    Haala, N.; Cavegn, S.

    2016-06-01

    Ongoing innovations in matching algorithms are continuously improving the quality of geometric surface representations generated automatically from aerial images. This development motivated the launch of the joint ISPRS/EuroSDR project "Benchmark on High Density Aerial Image Matching", which aims on the evaluation of photogrammetric 3D data capture in view of the current developments in dense multi-view stereo-image matching. Originally, the test aimed on image based DSM computation from conventional aerial image flights for different landuse and image block configurations. The second phase then put an additional focus on high quality, high resolution 3D geometric data capture in complex urban areas. This includes both the extension of the test scenario to oblique aerial image flights as well as the generation of filtered point clouds as additional output of the respective multi-view reconstruction. The paper uses the preliminary outcomes of the benchmark to demonstrate the state-of-the-art in airborne image matching with a special focus of high quality geometric data capture in urban scenarios.

  10. Injection of auxiliary electrons for increasing the plasma density in highly charged and high intensity ion sources

    Odorici, F., E-mail: fabrizio.odorici@bo.infn.it; Malferrari, L.; Montanari, A. [INFN—Bologna, Viale B. Pichat, 6/2, 40127 Bologna (Italy); Rizzoli, R. [INFN—Bologna, Viale B. Pichat, 6/2, 40127 Bologna (Italy); CNR–Istituto per la Microelettronica ed i Microsistemi, Via Gobetti 101, 40129 Bologna (Italy); Mascali, D.; Castro, G.; Celona, L.; Gammino, S.; Neri, L. [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy)

    2016-02-15

    Different electron guns based on cold- or hot-cathode technologies have been developed since 2009 at INFN for operating within ECR plasma chambers as sources of auxiliary electrons, with the aim of boosting the source performances by means of a higher plasma lifetime and density. Their application to microwave discharge ion sources, where plasma is not confined, has required an improvement of the gun design, in order to “screen” the cathode from the plasma particles. Experimental tests carried out on a plasma reactor show a boost of the plasma density, ranging from 10% to 90% when the electron guns are used, as explained by plasma diffusion models.

  11. Injection of auxiliary electrons for increasing the plasma density in highly charged and high intensity ion sources.

    Odorici, F; Malferrari, L; Montanari, A; Rizzoli, R; Mascali, D; Castro, G; Celona, L; Gammino, S; Neri, L

    2016-02-01

    Different electron guns based on cold- or hot-cathode technologies have been developed since 2009 at INFN for operating within ECR plasma chambers as sources of auxiliary electrons, with the aim of boosting the source performances by means of a higher plasma lifetime and density. Their application to microwave discharge ion sources, where plasma is not confined, has required an improvement of the gun design, in order to "screen" the cathode from the plasma particles. Experimental tests carried out on a plasma reactor show a boost of the plasma density, ranging from 10% to 90% when the electron guns are used, as explained by plasma diffusion models.

  12. Study of Different Tissue Density Effects on the Dose Distribution of a 103Pd Brachytherapy Source Model MED3633

    Ali Asghar Mowlavi

    2010-09-01

    Full Text Available Introduction: Clinical application of encapsulated radioactive brachytherapy sources has a major role in cancer treatment. In the present research, the effects of different tissue densities on the dose distribution of a 103Pd brachytherapy source in a spherical phantom of 50 cm radius have been studied. Material and Methods: As is well known, absorbed dose in tissue depends to its density, but this difference is not clear in measurements. Therefore, we applied the MCNP code to evaluate the effect of density on the dose distribution. 103Pd brachytherapy sources are used to treat prostate, breast and other cancers. Results: Absorbed dose has been calculated and presented around a source placed in the center of the phantom for different tissue densities. Also, we derived anisotropy and radial dose functions and compared our Monte Carlo results with experimental results of Rivard and Li et al. for F(1, θ and g(r in 1.040 g/cm3 tissue. Conclusion: The results of this study show that relative dose variations around the source center are very considerable at different densities, because of the presence of a photoabsorber (Au-Cu alloy in the source core. Dose variation exceeds 80% at the point (Z = 2.4 mm, Y = 0 mm. Computed values of anisotropy and radial dose functions are in good agreement with the experimental results of Rivard and Li et al.

  13. Investigation of the HU-density conversion method and comparison of dose distribution for dose calculation on MV cone beam CT images

    Kim, Min Joo; Lee, Seu Ran; Suh, Tae Suk [Dept. of Biomedical Engineering, The Catholic University of Korea, Bucheon (Korea, Republic of)

    2011-11-15

    Modern radiation therapy techniques, such as Image-guided radiation therapy (IGRT), Adaptive radiation therapy (ART) has become a routine clinical practice on linear accelerators for the increase the tumor dose conformity and improvement of normal tissue sparing at the same time. For these highly developed techniques, megavoltage cone beam computed tomography (MVCBCT) system produce volumetric images at just one rotation of the x-ray beam source and detector on the bottom of conventional linear accelerator for real-time application of patient condition into treatment planning. MV CBCT image scan be directly registered to a reference CT data set which is usually kilo-voltage fan-beam computed tomography (kVFBCT) on treatment planning system and the registered image scan be used to adjust patient set-up error. However, to use MV CBCT images in radiotherapy, reliable electron density (ED) distribution are required. Patients scattering, beam hardening and softening effect caused by different energy application between kVCT, MV CBCT can cause cupping artifacts in MV CBCT images and distortion of Houns field Unit (HU) to ED conversion. The goal of this study, for reliable application of MV CBCT images into dose calculation, MV CBCT images was modified to correct distortion of HU to ED using the relationship of HU and ED from kV FBCT and MV CBCT images. The HU-density conversion was performed on MV CBCT image set using Dose difference map was showing in Figure 1. Finally, percentage differences above 3% were reduced depending on applying density calibration method. As a result, total error co uld be reduced to under 3%. The present study demonstrates that dose calculation accuracy using MV CBCT image set can be improved my applying HU-density conversion method. The dose calculation and comparison of dose distribution from MV CBCT image set with/without HU-density conversion method was performed. An advantage of this study compared to other approaches is that HU-density

  14. Probability Density Components Analysis: A New Approach to Treatment and Classification of SAR Images

    Osmar Abílio de Carvalho Júnior

    2014-04-01

    Full Text Available Speckle noise (salt and pepper is inherent to synthetic aperture radar (SAR, which causes a usual noise-like granular aspect and complicates the image classification. In SAR image analysis, the spatial information might be a particular benefit for denoising and mapping classes characterized by a statistical distribution of the pixel intensities from a complex and heterogeneous spectral response. This paper proposes the Probability Density Components Analysis (PDCA, a new alternative that combines filtering and frequency histogram to improve the classification procedure for the single-channel synthetic aperture radar (SAR images. This method was tested on L-band SAR data from the Advanced Land Observation System (ALOS Phased-Array Synthetic-Aperture Radar (PALSAR sensor. The study area is localized in the Brazilian Amazon rainforest, northern Rondônia State (municipality of Candeias do Jamari, containing forest and land use patterns. The proposed algorithm uses a moving window over the image, estimating the probability density curve in different image components. Therefore, a single input image generates an output with multi-components. Initially the multi-components should be treated by noise-reduction methods, such as maximum noise fraction (MNF or noise-adjusted principal components (NAPCs. Both methods enable reducing noise as well as the ordering of multi-component data in terms of the image quality. In this paper, the NAPC applied to multi-components provided large reductions in the noise levels, and the color composites considering the first NAPC enhance the classification of different surface features. In the spectral classification, the Spectral Correlation Mapper and Minimum Distance were used. The results obtained presented as similar to the visual interpretation of optical images from TM-Landsat and Google Maps.

  15. Restoration of Thickness, Density, and Volume for Highly Blurred Thin Cortical Bones in Clinical CT Images.

    Pakdel, Amirreza; Hardisty, Michael; Fialkov, Jeffrey; Whyne, Cari

    2016-11-01

    In clinical CT images containing thin osseous structures, accurate definition of the geometry and density is limited by the scanner's resolution and radiation dose. This study presents and validates a practical methodology for restoring information about thin bone structure by volumetric deblurring of images. The methodology involves 2 steps: a phantom-free, post-reconstruction estimation of the 3D point spread function (PSF) from CT data sets, followed by iterative deconvolution using the PSF estimate. Performance of 5 iterative deconvolution algorithms, blind, Richardson-Lucy (standard, plus Total Variation versions), modified residual norm steepest descent (MRNSD), and Conjugate Gradient Least-Squares were evaluated using CT scans of synthetic cortical bone phantoms. The MRNSD algorithm resulted in the highest relative deblurring performance as assessed by a cortical bone thickness error (0.18 mm) and intensity error (150 HU), and was subsequently applied on a CT image of a cadaveric skull. Performance was compared against micro-CT images of the excised thin cortical bone samples from the skull (average thickness 1.08 ± 0.77 mm). Error in quantitative measurements made from the deblurred images was reduced 82% (p < 0.01) for cortical thickness and 55% (p < 0.01) for bone mineral mass. These results demonstrate a significant restoration of geometrical and radiological density information derived for thin osseous features.

  16. Advanced Calibration Source for Planetary and Earth Observing Imaging

    National Aeronautics and Space Administration — Planetary and Earth imaging requires radiometrically calibrated and stable imaging sensors.  Radiometric calibration enables the ability to remove or mitigate...

  17. Dual-source CT coronary imaging in heart transplant recipients: image quality and optimal reconstruction interval

    Bastarrika, Gorka; Arraiza, Maria; Pueyo, Jesus C.; Cecco, Carlo N. de; Ubilla, Matias; Mastrobuoni, Stefano; Rabago, Gregorio

    2008-01-01

    The image quality and optimal reconstruction interval for coronary arteries in heart transplant recipients undergoing non-invasive dual-source computed tomography (DSCT) coronary angiography was evaluated. Twenty consecutive heart transplant recipients who underwent DSCT coronary angiography were included (19 male, one female; mean age 63.1±10.7 years). Data sets were reconstructed in 5% steps from 30% to 80% of the R-R interval. Two blinded independent observers assessed the image quality of each coronary segments using a five-point scale (from 0 = not evaluative to 4=excellent quality). A total of 289 coronary segments in 20 heart transplant recipients were evaluated. Mean heart rate during the scan was 89.1±10.4 bpm. At the best reconstruction interval, diagnostic image quality (score ≥2) was obtained in 93.4% of the coronary segments (270/289) with a mean image quality score of 3.04± 0.63. Systolic reconstruction intervals provided better image quality scores than diastolic reconstruction intervals (overall mean quality scores obtained with the systolic and diastolic reconstructions 3.03±1.06 and 2.73±1.11, respectively; P<0.001). Different systolic reconstruction intervals (35%, 40%, 45% of RR interval) did not yield to significant differences in image quality scores for the coronary segments (P=0.74). Reconstructions obtained at the systolic phase of the cardiac cycle allowed excellent diagnostic image quality coronary angiograms in heart transplant recipients undergoing DSCT coronary angiography. (orig.)

  18. Value of diffusion-Weighted imaging in evaluating the cellularity density of prostate cancer

    Liu Jingang; Wang Xizhen; Wang Bin; Niu Qingliang; Liu Qiang

    2008-01-01

    Objective: To study the cellularity density of prostate cancer (PCa) with diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC). Methods: 38 patients with histologically proven prostate cancer (PCa) underwent DWI with a 1.5 T MR scanner using a pelvic phased array multi-coil. The ADC values of PCa, benign prostatic hyperplasia (BPH), and peripheral zone (PZ) were calculated. The cellularity density of PCa was recorded according to hematoxylin and eosin (HE) staining. The relationship between ADC value and cellularity density of PCa was analyzed with Pearson correlation coefficient. Results: The ADC values of PCa, BPH, and PZ were (49.32±12.68)×10 -5 mm 2 /s, (86.73±26.75)×10 -5 mm 2 /s and (126.25±27.21)×10 -5 mm 2 /s, respectively. The ADC value of PCa was significantly lower than that of BPH and PZ (P<005). The cellularity density of PCa was 12.9%. The ADC value reversely related to the cellularity density of prostate cancer (r=-0.646, P<005). Conclusion: The ADC value can reflect the cellularity density of PCa. (authors)

  19. MEG source imaging method using fast L1 minimum-norm and its applications to signals with brain noise and human resting-state source amplitude images.

    Huang, Ming-Xiong; Huang, Charles W; Robb, Ashley; Angeles, AnneMarie; Nichols, Sharon L; Baker, Dewleen G; Song, Tao; Harrington, Deborah L; Theilmann, Rebecca J; Srinivasan, Ramesh; Heister, David; Diwakar, Mithun; Canive, Jose M; Edgar, J Christopher; Chen, Yu-Han; Ji, Zhengwei; Shen, Max; El-Gabalawy, Fady; Levy, Michael; McLay, Robert; Webb-Murphy, Jennifer; Liu, Thomas T; Drake, Angela; Lee, Roland R

    2014-01-01

    The present study developed a fast MEG source imaging technique based on Fast Vector-based Spatio-Temporal Analysis using a L1-minimum-norm (Fast-VESTAL) and then used the method to obtain the source amplitude images of resting-state magnetoencephalography (MEG) signals for different frequency bands. The Fast-VESTAL technique consists of two steps. First, L1-minimum-norm MEG source images were obtained for the dominant spatial modes of sensor-waveform covariance matrix. Next, accurate source time-courses with millisecond temporal resolution were obtained using an inverse operator constructed from the spatial source images of Step 1. Using simulations, Fast-VESTAL's performance was assessed for its 1) ability to localize multiple correlated sources; 2) ability to faithfully recover source time-courses; 3) robustness to different SNR conditions including SNR with negative dB levels; 4) capability to handle correlated brain noise; and 5) statistical maps of MEG source images. An objective pre-whitening method was also developed and integrated with Fast-VESTAL to remove correlated brain noise. Fast-VESTAL's performance was then examined in the analysis of human median-nerve MEG responses. The results demonstrated that this method easily distinguished sources in the entire somatosensory network. Next, Fast-VESTAL was applied to obtain the first whole-head MEG source-amplitude images from resting-state signals in 41 healthy control subjects, for all standard frequency bands. Comparisons between resting-state MEG sources images and known neurophysiology were provided. Additionally, in simulations and cases with MEG human responses, the results obtained from using conventional beamformer technique were compared with those from Fast-VESTAL, which highlighted the beamformer's problems of signal leaking and distorted source time-courses. © 2013.

  20. Analysis of the image of pion-emitting sources in the source center-of-mass frame

    Ren, Yanyu; Feng, Qichun; Huo, Lei; Zhang, Jingbo; Liu, Jianli; Tang, Guixin [Harbin Institute of Technology, Department of Physics, Harbin, Heilongjiang (China); Zhang, Weining [Harbin Institute of Technology, Department of Physics, Harbin, Heilongjiang (China); Dalian University of Technology, School of Physics and Optoelectronic Technology, Dalian, Liaoning (China)

    2017-08-15

    In this paper, we try a method to extract the image of pion-emitting source function in the center-of-mass frame of the source (CMFS). We choose identical pion pairs according to the difference of their energy and use these pion pairs to build the correlation function. The purpose is to reduce the effect of ΔEΔt, thus the corresponding imaging result can tend to the real source function. We examine the effect of this method by comparing its results with real source functions extracted from models directly. (orig.)

  1. A generalized model for optimal transport of images including dissipation and density modulation

    Maas, Jan

    2015-11-01

    © EDP Sciences, SMAI 2015. In this paper the optimal transport and the metamorphosis perspectives are combined. For a pair of given input images geodesic paths in the space of images are defined as minimizers of a resulting path energy. To this end, the underlying Riemannian metric measures the rate of transport cost and the rate of viscous dissipation. Furthermore, the model is capable to deal with strongly varying image contrast and explicitly allows for sources and sinks in the transport equations which are incorporated in the metric related to the metamorphosis approach by Trouvé and Younes. In the non-viscous case with source term existence of geodesic paths is proven in the space of measures. The proposed model is explored on the range from merely optimal transport to strongly dissipative dynamics. For this model a robust and effective variational time discretization of geodesic paths is proposed. This requires to minimize a discrete path energy consisting of a sum of consecutive image matching functionals. These functionals are defined on corresponding pairs of intensity functions and on associated pairwise matching deformations. Existence of time discrete geodesics is demonstrated. Furthermore, a finite element implementation is proposed and applied to instructive test cases and to real images. In the non-viscous case this is compared to the algorithm proposed by Benamou and Brenier including a discretization of the source term. Finally, the model is generalized to define discrete weighted barycentres with applications to textures and objects.

  2. Profiles of plasma parameters and density of negative hydrogen ions by laser detachment measurements in RF-driven ion sources

    Christ-Koch, Sina

    2007-01-01

    This work shows the application of the Laserdetachment method for spatially resolved measurements of negative Hydrogen/Deuterium ion density. It was applied on a high power low pressure RF-driven ion source. The Laser detachment method is based on the measurement of electron currents on a positively biased Langmuir probe before and during/after a laser pulse. The density ratio of negative ions to electrons can be derived from the ratio of currents to the probe. The absolute density of negative ions can be obtained when the electron density is measured with the standard Langmuir probe setup. Measurements with the Langmuir probe additionally yield information about the floating and plasma potential, the electron temperature and the density of positive ions. The Laser detachment setup had to be adapted to the special conditions of the RF-driven source. In particular the existence of RF fields (1 MHz), high source potential (-20 kV), magnetic fields (∝ 7 mT) and caesium inside the source had to be considered. The density of negative ions could be identified in the range of n(H - )=1.10 17 1/m 3 , which is in the same order of magnitude as the electron density. Only the application of the Laser detachment method with the Langmuir probe measurements will yield spatially resolved plasma parameters and H- density profiles. The influence of diverse external parameters, such as pressure, RF-power, magnetic fields on the plasma parameters and their profiles were studied and explained. Hence, the measurements lead to a detailed understanding of the processes inside the source. (orig.)

  3. Quantitative Assessment of Mammary Gland Density in Rodents Using Digital Image Analysis

    Thompson Henry J

    2011-06-01

    Full Text Available Abstract Background Rodent models have been used extensively to study mammary gland development and for studies of toxicology and carcinogenesis. Mammary gland gross morphology can visualized via the excision of intact mammary gland chains following fixation and staining with carmine using a tissue preparation referred to as a whole mount. Methods are described for the automated collection of digital images from an entire mammary gland whole mount and for the interrogation of digital data using a "masking" technique available with Image-Pro® plus image analysis software (Mediacybernetics. Silver Spring, MD. Results Parallel to mammographic analysis in humans, measurements of rodent mammary gland density were derived from area-based or volume-based algorithms and included: total circumscribed mammary fat pad mass, mammary epithelial mass, and epithelium-free fat pad mass. These values permitted estimation of absolute mass of mammary epithelium as well as breast density. The biological plausibility of these measurements was evaluated in mammary whole mounts from rats and mice. During mammary gland development, absolute epithelial mass increased linearly without significant changes in mammographic density. Treatment of rodents with tamoxifen, 9-cis-retinoic acid, or ovariectomy, and occurrence of diet induced obesity decreased both absolute epithelial mass and mammographic density. The area and volumetric methods gave similar results. Conclusions Digital image analysis can be used for screening agents for potential impact on reproductive toxicity or carcinogenesis as well as for mechanistic studies, particularly for cumulative effects on mammary epithelial mass as well as translational studies of mechanisms that explain the relationship between epithelial mass and cancer risk.

  4. Evaluation of electrical crosstalk in high-density photodiode arrays for X-ray imaging applications

    Ji Fan; Juntunen, Mikko; Hietanen, Iiro

    2009-01-01

    Electrical crosstalk is one of the important parameters in the photodiode array detector for X-ray imaging applications, and it becomes more important when the density of the photodiode array becomes higher. This paper presents the design of the high-density photodiode array with 250 μm pitch and 50 μm gap. The electrical crosstalk of the demonstrated samples is evaluated and compared with different electrode configurations: cathode bias mode and anode bias mode. The measurement results show good electrical crosstalk, ∼0.23%, in cathode bias mode regardless of the bias voltage, and slightly decreased or increased electrical crosstalk in anode bias mode. Moreover, the quantum efficiency is also evaluated from the same samples, and it behaves similar to the electrical crosstalk. Finally, some design guidance of the high-density photodiode array is given based on the discussion.

  5. Feature extraction using convolutional neural network for classifying breast density in mammographic images

    Thomaz, Ricardo L.; Carneiro, Pedro C.; Patrocinio, Ana C.

    2017-03-01

    Breast cancer is the leading cause of death for women in most countries. The high levels of mortality relate mostly to late diagnosis and to the direct proportionally relationship between breast density and breast cancer development. Therefore, the correct assessment of breast density is important to provide better screening for higher risk patients. However, in modern digital mammography the discrimination among breast densities is highly complex due to increased contrast and visual information for all densities. Thus, a computational system for classifying breast density might be a useful tool for aiding medical staff. Several machine-learning algorithms are already capable of classifying small number of classes with good accuracy. However, machinelearning algorithms main constraint relates to the set of features extracted and used for classification. Although well-known feature extraction techniques might provide a good set of features, it is a complex task to select an initial set during design of a classifier. Thus, we propose feature extraction using a Convolutional Neural Network (CNN) for classifying breast density by a usual machine-learning classifier. We used 307 mammographic images downsampled to 260x200 pixels to train a CNN and extract features from a deep layer. After training, the activation of 8 neurons from a deep fully connected layer are extracted and used as features. Then, these features are feedforward to a single hidden layer neural network that is cross-validated using 10-folds to classify among four classes of breast density. The global accuracy of this method is 98.4%, presenting only 1.6% of misclassification. However, the small set of samples and memory constraints required the reuse of data in both CNN and MLP-NN, therefore overfitting might have influenced the results even though we cross-validated the network. Thus, although we presented a promising method for extracting features and classifying breast density, a greater database is

  6. Visualization and analysis of pulsed ion beam energy density profile with infrared imaging

    Isakova, Y. I.; Pushkarev, A. I.

    2018-03-01

    Infrared imaging technique was used as a surface temperature-mapping tool to characterize the energy density distribution of intense pulsed ion beams on a thin metal target. The technique enables the measuring of the total ion beam energy and the energy density distribution along the cross section and allows one to optimize the operation of an ion diode and control target irradiation mode. The diagnostics was tested on the TEMP-4M accelerator at TPU, Tomsk, Russia and on the TEMP-6 accelerator at DUT, Dalian, China. The diagnostics was applied in studies of the dynamics of the target cooling in vacuum after irradiation and in the experiments with target ablation. Errors caused by the target ablation and target cooling during measurements have been analyzed. For Fluke Ti10 and Fluke Ti400 infrared cameras, the technique can achieve surface energy density sensitivity of 0.05 J/cm2 and spatial resolution of 1-2 mm. The thermal imaging diagnostics does not require expensive consumed materials. The measurement time does not exceed 0.1 s; therefore, this diagnostics can be used for the prompt evaluation of the energy density distribution of a pulsed ion beam and during automation of the irradiation process.

  7. Partitioning the sources of demographic variation reveals density-dependent nest predation in an island bird population.

    Sofaer, Helen R; Sillett, T Scott; Langin, Kathryn M; Morrison, Scott A; Ghalambor, Cameron K

    2014-07-01

    Ecological factors often shape demography through multiple mechanisms, making it difficult to identify the sources of demographic variation. In particular, conspecific density can influence both the strength of competition and the predation rate, but density-dependent competition has received more attention, particularly among terrestrial vertebrates and in island populations. A better understanding of how both competition and predation contribute to density-dependent variation in fecundity can be gained by partitioning the effects of density on offspring number from its effects on reproductive failure, while also evaluating how biotic and abiotic factors jointly shape demography. We examined the effects of population density and precipitation on fecundity, nest survival, and adult survival in an insular population of orange-crowned warblers (Oreothlypis celata) that breeds at high densities and exhibits a suite of traits suggesting strong intraspecific competition. Breeding density had a negative influence on fecundity, but it acted by increasing the probability of reproductive failure through nest predation, rather than through competition, which was predicted to reduce the number of offspring produced by successful individuals. Our results demonstrate that density-dependent nest predation can underlie the relationship between population density and fecundity even in a high-density, insular population where intraspecific competition should be strong.

  8. Functional imaging of the human brain using a modular, fibre-less, high-density diffuse optical tomography system.

    Chitnis, Danial; Cooper, Robert J; Dempsey, Laura; Powell, Samuel; Quaggia, Simone; Highton, David; Elwell, Clare; Hebden, Jeremy C; Everdell, Nicholas L

    2016-10-01

    We present the first three-dimensional, functional images of the human brain to be obtained using a fibre-less, high-density diffuse optical tomography system. Our technology consists of independent, miniaturized, silicone-encapsulated DOT modules that can be placed directly on the scalp. Four of these modules were arranged to provide up to 128, dual-wavelength measurement channels over a scalp area of approximately 60 × 65 mm 2 . Using a series of motor-cortex stimulation experiments, we demonstrate that this system can obtain high-quality, continuous-wave measurements at source-detector separations ranging from 14 to 55 mm in adults, in the presence of hair. We identify robust haemodynamic response functions in 5 out of 5 subjects, and present diffuse optical tomography images that depict functional haemodynamic responses that are well-localized in all three dimensions at both the individual and group levels. This prototype modular system paves the way for a new generation of wearable, wireless, high-density optical neuroimaging technologies.

  9. Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

    Jones, Christopher P., E-mail: cj0810@bristol.ac.uk [Interface Analysis Centre, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Brenner, Ceri M. [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Stitt, Camilla A. [Interface Analysis Centre, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Armstrong, Chris; Rusby, Dean R. [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Mirfayzi, Seyed R. [Centre for Plasma Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Wilson, Lucy A. [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Alejo, Aarón; Ahmed, Hamad [Centre for Plasma Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Allott, Ric [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Butler, Nicholas M.H. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Clarke, Robert J.; Haddock, David; Hernandez-Gomez, Cristina [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Higginson, Adam [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Murphy, Christopher [Department of Physics, University of York, York YO10 5DD (United Kingdom); Notley, Margaret [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Paraskevoulakos, Charilaos [Interface Analysis Centre, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Jowsey, John [Ground Floor North B582, Sellafield Ltd, Seascale, Cumbria CA20 1PG (United Kingdom); and others

    2016-11-15

    Highlights: • X-ray generation was achieved via laser interaction with a tantalum thin foil target. • Picosecond X-ray pulse from a sub-mm spot generated high resolution images. • MeV X-ray emission is possible, permitting analysis of full scale waste containers. • In parallel neutron emission of 10{sup 7}–10{sup 9} neutrons per steradian per pulse was attained. • Development of a 10 Hz diode pumped laser system for waste monitoring is envisioned. - Abstract: A small scale sample nuclear waste package, consisting of a 28 mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500 keV), with a source size of <0.5 mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30 cm{sup 2} scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10 Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned.

  10. Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

    Jones, Christopher P.; Brenner, Ceri M.; Stitt, Camilla A.; Armstrong, Chris; Rusby, Dean R.; Mirfayzi, Seyed R.; Wilson, Lucy A.; Alejo, Aarón; Ahmed, Hamad; Allott, Ric; Butler, Nicholas M.H.; Clarke, Robert J.; Haddock, David; Hernandez-Gomez, Cristina; Higginson, Adam; Murphy, Christopher; Notley, Margaret; Paraskevoulakos, Charilaos; Jowsey, John

    2016-01-01

    Highlights: • X-ray generation was achieved via laser interaction with a tantalum thin foil target. • Picosecond X-ray pulse from a sub-mm spot generated high resolution images. • MeV X-ray emission is possible, permitting analysis of full scale waste containers. • In parallel neutron emission of 10"7–10"9 neutrons per steradian per pulse was attained. • Development of a 10 Hz diode pumped laser system for waste monitoring is envisioned. - Abstract: A small scale sample nuclear waste package, consisting of a 28 mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500 keV), with a source size of <0.5 mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30 cm"2 scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10 Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned.

  11. Detection of a compact radio source near the center of a gravitational lens: quasar image or galactic core

    Gorenstein, M.V.; Shapiro, I.I.; Cohen, N.L.

    1983-01-01

    By use of a new, very sensitive interferometric system, a faint, compact radio source has been detected near the center of the galaxy that acts as the main part of a gravitational lens. This lens forms two previously discovered images of the quasar Q0957 + 561, which lies in the direction of the constellation Ursa Major. The newly detected source has a core smaller than 0.002 arc second in diameter with a flux density of 0.6 +- 0.1 millijansky at the 13-centimeter wavelength of the radio observations. This source could be the predicted third image of the transparent gravitational lens, the central core of the galaxy, or some combination of the two. It is not yet possible to choose reliably between these alternatives

  12. Neurite orientation dispersion and density imaging in the substantia nigra in idiopathic Parkinson disease.

    Kamagata, Koji; Hatano, Taku; Okuzumi, Ayami; Motoi, Yumiko; Abe, Osamu; Shimoji, Keigo; Kamiya, Kouhei; Suzuki, Michimasa; Hori, Masaaki; Kumamaru, Kanako K; Hattori, Nobutaka; Aoki, Shigeki

    2016-08-01

    We used neurite orientation dispersion and density imaging (NODDI) to quantify changes in the substantia nigra pars compacta (SNpc) and striatum in Parkinson disease (PD). Diffusion-weighted magnetic resonance images were acquired from 58 PD patients and 36 age- and sex-matched controls. The intracellular volume fraction (Vic), orientation dispersion index (OD), and isotropic volume fraction (Viso) of the basal ganglia were compared between groups. Multivariate logistic regression analysis determined which diffusion parameters were independent predictors of PD. Receiver operating characteristic (ROC) analysis compared the diagnostic accuracies of the evaluated indices. Pearson coefficient analysis correlated each diffusional parameter with disease severity. Vic in the contralateral SNpc and putamen were significantly lower in PD patients than in healthy controls (P disease severity. Multivariate logistic analysis revealed that Vic (P = 0.0000046) and mean diffusivity (P = 0.019) in the contralateral SNpc were the independent predictors of PD. In the ROC analysis, Vic in the contralateral SNpc showed the best diagnostic performance (mean cutoff, 0.62; sensitivity, 0.88; specificity, 0.83). NODDI is likely to be useful for diagnosing PD and assessing its progression. • Neurite orientation dispersion and density imaging (NODDI) is a new diffusion MRI technique • NODDI estimates neurite microstructure more specifically than diffusion tensor imaging • By using NODDI, nigrostriatal alterations in PD can be evaluated in vivo • NOODI is useful for diagnosing PD and assessing its disease progression.

  13. Scattered image artifacts from cone beam computed tomography and its clinical potential in bone mineral density estimation.

    Ko, Hoon; Jeong, Kwanmoon; Lee, Chang-Hoon; Jun, Hong Young; Jeong, Changwon; Lee, Myeung Su; Nam, Yunyoung; Yoon, Kwon-Ha; Lee, Jinseok

    2016-01-01

    Image artifacts affect the quality of medical images and may obscure anatomic structure and pathology. Numerous methods for suppression and correction of scattered image artifacts have been suggested in the past three decades. In this paper, we assessed the feasibility of use of information on scattered artifacts for estimation of bone mineral density (BMD) without dual-energy X-ray absorptiometry (DXA) or quantitative computed tomographic imaging (QCT). To investigate the relationship between scattered image artifacts and BMD, we first used a forearm phantom and cone-beam computed tomography. In the phantom, we considered two regions of interest-bone-equivalent solid material containing 50 mg HA per cm(-3) and water-to represent low- and high-density trabecular bone, respectively. We compared the scattered image artifacts in the high-density material with those in the low-density material. The technique was then applied to osteoporosis patients and healthy subjects to assess its feasibility for BMD estimation. The high-density material produced a greater number of scattered image artifacts than the low-density material. Moreover, the radius and ulna of healthy subjects produced a greater number of scattered image artifacts than those from osteoporosis patients. Although other parameters, such as bone thickness and X-ray incidence, should be considered, our technique facilitated BMD estimation directly without DXA or QCT. We believe that BMD estimation based on assessment of scattered image artifacts may benefit the prevention, early treatment and management of osteoporosis.

  14. Probability density function modeling of scalar mixing from concentrated sources in turbulent channel flow

    Bakosi, J.; Franzese, P.; Boybeyi, Z.

    2007-11-01

    Dispersion of a passive scalar from concentrated sources in fully developed turbulent channel flow is studied with the probability density function (PDF) method. The joint PDF of velocity, turbulent frequency and scalar concentration is represented by a large number of Lagrangian particles. A stochastic near-wall PDF model combines the generalized Langevin model of Haworth and Pope [Phys. Fluids 29, 387 (1986)] with Durbin's [J. Fluid Mech. 249, 465 (1993)] method of elliptic relaxation to provide a mathematically exact treatment of convective and viscous transport with a nonlocal representation of the near-wall Reynolds stress anisotropy. The presence of walls is incorporated through the imposition of no-slip and impermeability conditions on particles without the use of damping or wall-functions. Information on the turbulent time scale is supplied by the gamma-distribution model of van Slooten et al. [Phys. Fluids 10, 246 (1998)]. Two different micromixing models are compared that incorporate the effect of small scale mixing on the transported scalar: the widely used interaction by exchange with the mean and the interaction by exchange with the conditional mean model. Single-point velocity and concentration statistics are compared to direct numerical simulation and experimental data at Reτ=1080 based on the friction velocity and the channel half width. The joint model accurately reproduces a wide variety of conditional and unconditional statistics in both physical and composition space.

  15. Far-infrared imaging arrays for fusion plasma density and magnetic field measurements

    Neikirk, D.P.; Rutledge, D.B.

    1982-01-01

    Far-infrared imaging detector arrays are required for the determination of density and local magnetic field in fusion plasmas. Analytic calculations point out the difficulties with simple printed slot and dipole antennas on ungrounded substrates for use in submillimeter wave imaging arrays because of trapped surface waves. This is followed by a discussion of the use of substrate-lens coupling to eliminate the associated trapped surface modes responsible for their poor performance. This integrates well with a modified bow-tie antenna and permits diffraction-limited imaging. Arrays using bismuth microbolometers have been successfully fabricated and tested at 1222μm and 119μm. A 100 channel pilot experiment designed for the UCLA Microtor tokamak is described. (author)

  16. Z-pinches as intense x-ray sources for high energy density physics application

    Matzen, M.K.

    1997-01-01

    Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator at Sandia National Laboratories, for example, currents of 6 to 8 MA with a risetime of less than 50 ns are driven through cylindrically-symmetric loads, producing implosions velocities as high as 100 cm/μs and x-ray energies as high as 500 kJ. The keV component of the resulting x-ray spectrum has been used for many years 8 a radiation source for material response studies. Alternatively, the x-ray output can be thermalized into a near-Planckian x-ray source by containing it within a large cylindrical radiation case. These large volume, long-lived radiation sources have recently been used for ICF-relevant ablator physics experiments as well as astrophysical opacity and radiation-material interaction experiments. Hydromagnetic Rayleigh-Taylor instabilities and cylindrical load symmetry are critical, limiting factors in determining the assembled plasma densities and temperatures, and thus in the x-ray pulse widths that can be produced on these accelerators. In recent experiments on the Saturn accelerator, these implosion nonuniformities have been minimized by using uniform-fill gas puff loads or by using wire arrays with as many a 192 wires. These techniques produced significant improvements in the pinched plasma quality, Zn reproducibility, and x-ray output power. X-ray pulse widths of less than 5 ns and peak powers of 75±10 TW have been achieved with arrays of 120 tungsten wires. These powers represent greater than a factor of three in power amplification over the electrical power of the Saturn n accelerator, and are a record for x-ray powers in the laboratory

  17. Construction of a voxel model from CT images with density derived from CT numbers

    Cheng Mengyun; Zeng Qin; Cao Ruifen; Li Gui; Zheng Huaqing; Huang Shanqing; Song Gang; Wu Yican

    2011-01-01

    The voxel models representing human anatomy have been developed to calculate dose distribution in human body, while the density and elemental composition are the most important physical properties of voxel model. Usually, when creating the Monte Carlo input files, the average tissue densities recommended in ICRP Publication were used to assign each voxel in the existing voxel models. As each tissue consists of many voxels with different densities, the conventional method of average tissue densities failed to take account of the voxel's discrepancy, and therefore could not represent human anatomy faithfully. To represent human anatomy more faithfully, a method was implemented to assign each voxel, the densities of which were derived from CT number. In order to compare with the traditional method, we constructed two models from the cadaver specimen dataset. A CT-based pelvic voxel model called Pelvis-CT model was constructed, the densities of which were derived from the CT numbers. A color photograph-based pelvic voxel model called Pelvis-Photo model was also constructed, the densities of which were taken from ICRP Publication. The CT images and the color photographs were obtained from the same female cadaver specimen. The Pelvis-CT and Pelvis-Photo models were both ported into Monte Carlo code MCNP to calculate the conversion coefficients from kerma free-in-air to absorbed dose for external monoenergetic photon beams with energies of 0.1, 1 and 10 MeV under anterior-posterior (AP) geometry. The results were compared with those of given in ICRP Publication 74. Differences of up to 50% were observed between conversion coefficients of Pelvis-CT and Pelvis- Photo models, moreover the discrepancies decreased for the photon beams with higher energies. The overall trend of conversion coefficients of the Pelvis-CT model agreed well with that of ICRP Publication 74 data. (author)

  18. 3-D time-domain induced polarization tomography: a new approach based on a source current density formulation

    Soueid Ahmed, A.; Revil, A.

    2018-04-01

    Induced polarization (IP) of porous rocks can be associated with a secondary source current density, which is proportional to both the intrinsic chargeability and the primary (applied) current density. This gives the possibility of reformulating the time domain induced polarization (TDIP) problem as a time-dependent self-potential-type problem. This new approach implies a change of strategy regarding data acquisition and inversion, allowing major time savings for both. For inverting TDIP data, we first retrieve the electrical resistivity distribution. Then, we use this electrical resistivity distribution to reconstruct the primary current density during the injection/retrieval of the (primary) current between the current electrodes A and B. The time-lapse secondary source current density distribution is determined given the primary source current density and a distribution of chargeability (forward modelling step). The inverse problem is linear between the secondary voltages (measured at all the electrodes) and the computed secondary source current density. A kernel matrix relating the secondary observed voltages data to the source current density model is computed once (using the electrical conductivity distribution), and then used throughout the inversion process. This recovered source current density model is in turn used to estimate the time-dependent chargeability (normalized voltages) in each cell of the domain of interest. Assuming a Cole-Cole model for simplicity, we can reconstruct the 3-D distributions of the relaxation time τ and the Cole-Cole exponent c by fitting the intrinsic chargeability decay curve to a Cole-Cole relaxation model for each cell. Two simple cases are studied in details to explain this new approach. In the first case, we estimate the Cole-Cole parameters as well as the source current density field from a synthetic TDIP data set. Our approach is successfully able to reveal the presence of the anomaly and to invert its Cole

  19. Longitudinal study of arteriogenesis with swept source optical coherence tomography and hyperspectral imaging

    Poole, Kristin M.; Patil, Chetan A.; Nelson, Christopher E.; McCormack, Devin R.; Madonna, Megan C.; Duvall, Craig L.; Skala, Melissa C.

    2014-03-01

    Peripheral arterial disease (PAD) is an atherosclerotic disease of the extremities that leads to high rates of myocardial infarction and stroke, increased mortality, and reduced quality of life. PAD is especially prevalent in diabetic patients, and is commonly modeled by hind limb ischemia in mice to study collateral vessel development and test novel therapies. Current techniques used to assess recovery cannot obtain quantitative, physiological data non-invasively. Here, we have applied hyperspectral imaging and swept source optical coherence tomography (OCT) to study longitudinal changes in blood oxygenation and vascular morphology, respectively, intravitally in the diabetic mouse hind limb ischemia model. Additionally, recommended ranges for controlling physiological variability in blood oxygenation with respect to respiration rate and body core temperature were determined from a control animal experiment. In the longitudinal study with diabetic mice, hyperspectral imaging data revealed the dynamics of blood oxygenation recovery distally in the ischemic footpad. In diabetic mice, there is an early increase in oxygenation that is not sustained in the long term. Quantitative analysis of vascular morphology obtained from Hessian-filtered speckle variance OCT volumes revealed temporal dynamics in vascular density, total vessel length, and vessel diameter distribution in the adductor muscle of the ischemic limb. The combination of hyperspectral imaging and speckle variance OCT enabled acquisition of novel functional and morphological endpoints from individual animals, and provides a more robust platform for future preclinical evaluations of novel therapies for PAD.

  20. The Role of Skull Modeling in EEG Source Imaging for Patients with Refractory Temporal Lobe Epilepsy.

    Montes-Restrepo, Victoria; Carrette, Evelien; Strobbe, Gregor; Gadeyne, Stefanie; Vandenberghe, Stefaan; Boon, Paul; Vonck, Kristl; Mierlo, Pieter van

    2016-07-01

    We investigated the influence of different skull modeling approaches on EEG source imaging (ESI), using data of six patients with refractory temporal lobe epilepsy who later underwent successful epilepsy surgery. Four realistic head models with different skull compartments, based on finite difference methods, were constructed for each patient: (i) Three models had skulls with compact and spongy bone compartments as well as air-filled cavities, segmented from either computed tomography (CT), magnetic resonance imaging (MRI) or a CT-template and (ii) one model included a MRI-based skull with a single compact bone compartment. In all patients we performed ESI of single and averaged spikes marked in the clinical 27-channel EEG by the epileptologist. To analyze at which time point the dipole estimations were closer to the resected zone, ESI was performed at two time instants: the half-rising phase and peak of the spike. The estimated sources for each model were validated against the resected area, as indicated by the postoperative MRI. Our results showed that single spike analysis was highly influenced by the signal-to-noise ratio (SNR), yielding estimations with smaller distances to the resected volume at the peak of the spike. Although averaging reduced the SNR effects, it did not always result in dipole estimations lying closer to the resection. The proposed skull modeling approaches did not lead to significant differences in the localization of the irritative zone from clinical EEG data with low spatial sampling density. Furthermore, we showed that a simple skull model (MRI-based) resulted in similar accuracy in dipole estimation compared to more complex head models (based on CT- or CT-template). Therefore, all the considered head models can be used in the presurgical evaluation of patients with temporal lobe epilepsy to localize the irritative zone from low-density clinical EEG recordings.

  1. Imaging investigation of metabolic and endocrine bone disease of vertebral density

    Cai Yuezeng; Tian Xiali; Li Jingxue

    2006-01-01

    Objective: To probe vertebral density of metabolic and endocrine bone disease imaging features, characterize the regional distribution of bone trabecular in sandwich spine. Methods: Thirty-six patients who had the bone density abnormality appearance in radiograms were collected in this study. Twelve patients with sandwich spine were performed lumbar CT scan. Thirty-two healthy volunteers as control group were performed lumbar CT scan too. CT values of two groups were measured from different portions of vertebral body, and then were analysed. Twenty two patients were performed dual-energy x-ray absorptiometry (DXA). One patient was performed bone histomorphometry. Results: Abnormal density included decreased and increased density. Decreased density was found in different portions of all patients, which divided into general and regional type. Increased density was obviously in vertebrae, including diffusely increased density and sandwich spine. The mean CT values of superior, middle and inferior portions of sandwich vertebral body were (259.94±18.08), (182.96±34.85), (270.34±19.40) HU. The mean CT values of both superior and inferior portions of sandwich vertebral body were higher than that of control group. The mean CT values of superior and inferior portions of sandwich spine were higher than that of middle portion. The difference of mean CT values between superior and inferior portions had no statistical significance. The difference of CT values among the regions of superior and inferior portions had no statistical significance (F=0.457, 0.462, P>0.05). The difference of CT values among the regions of middle portion had statistical significance(F=4.539, P<0.05). The DXA measurement of sandwich spine showed high, normal and low BMD. Conclusion: The sandwich spine is useful to measure superior and inferior portions of sandwich vertebral body if QCT would be performed. Sandwich spine sign can be used as an imaging index of state evaluation. Increased density in

  2. The use of surface power for characterisation of structure-borne sound sources of low modal density

    Ohlrich, Mogens

    1996-01-01

    The use of the surface power methods for source characterisaiton of vibrating machinery of low modal density is investigated in this paper. It was demonstrated by Ohlrich and Larsen that this relatively simple, but very useful measurement technique for quantifying the vibratory strength of machin......The use of the surface power methods for source characterisaiton of vibrating machinery of low modal density is investigated in this paper. It was demonstrated by Ohlrich and Larsen that this relatively simple, but very useful measurement technique for quantifying the vibratory strength...

  3. “Hot cross bun” sign in multiple system atrophy with predominant cerebellar ataxia: A comparison between proton density-weighted imaging and T2-weighted imaging

    Kasahara, Seiko, E-mail: nuun077@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Miki, Yukio, E-mail: yukio.miki@med.osaka-cu.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Department of Radiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545–8585 (Japan); Kanagaki, Mitsunori, E-mail: mitsuk@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Kondo, Takayuki, E-mail: kondotak@kuhp.kyoto-u.ac.jp [Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Yamamoto, Akira, E-mail: yakira@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Morimoto, Emiko, E-mail: foresta@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Okada, Tomohisa, E-mail: tomokada@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Ito, Hidefumi, E-mail: itohid@kuhp.kyoto-u.ac.jp [Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Takahashi, Ryosuke, E-mail: ryosuket@kuhp.kyoto-u.ac.jp [Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); and others

    2012-10-15

    Objective: To investigate whether proton density-weighted imaging can detect the “hot cross bun” sign in the pons in multiple system atrophy with predominant cerebellar ataxia significantly better than T2-weighted imaging at 3 T. Methods: Sixteen consecutive patients with multiple system atrophy with predominant cerebellar ataxia according to the Consensus Criteria were reviewed. Axial unenhanced proton density-weighted imaging and T2-weighted imaging were obtained using a dual-echo fast spin-echo sequence at 3 T. Two neuroradiologists independently evaluated visualisation of the abnormal pontine signal using a 4-point visual grade from Grade 0 (no “hot cross bun” sign) to Grade 3 (prominent “hot cross bun” sign on two or more sequential slices). Differences in grade between proton density-weighted imaging and T2-weighted imaging were statistically analysed using the Wilcoxon signed-rank test. Results: In 11 patients (69%), a higher grade was given for proton density-weighted imaging than T2-weighted imaging. In 1 patient (6%), grades were the same (Grade 3) on both images. In the remaining 4 patients (25%), signal abnormalities were not detected on either image (Grade 0). The “hot cross bun” sign was thus observed significantly better on proton density-weighted imaging than on T2-weighted imaging (P = 0.001). Conclusions: The “hot cross bun” sign considered diagnostic for multiple system atrophy with predominant cerebellar ataxia is significantly better visualised on proton density-weighted imaging than on T2-weighted imaging at 3 T.

  4. Relationships between cone beam CT value and physical density in image guided radiation therapy

    Jiang Xiaoqin; Bai Sen; Zhong Renming; Tang Zhiquan; Jiang Qinfeng; Li Tao

    2007-01-01

    Objective: To evaluate the main factors affecting the relationship between physical density and CT value in cone-beam computed tomography(CBCT) for imaging guided radiation therapy(IGRT) by comparing the CT value in the image from cone-beam scanner and from fan-beam (FBCT) scanner of a reference phantom. Methods: A taking-park reference phantom with a set of tissue equivalent inserts was scanned at different energies different fields of view (FOV) for IGRT-CBCT and FBCT. The CT value of every insert was measured and compared. Results: The position of inserts in phantom, the size of phantom, the FOV of scanner and different energies had more effect on the relationships between physical density and the CT value from IGRT-CBCT than those from the normal FBCT. The higher the energy was, the less effect of the position of inserts in phantom, the size of phantom and the FOV of scanner on CT value, and the poorer density contrast was observed. Conclusion: At present, the CT value of IGRT-CBCT is not in the true HU value since the manufacturer has not corrected its number. Therefore, we are not able to use the CT value of CBCT for dose calculation in TPS. (authors)

  5. Microseismic imaging using a source-independent full-waveform inversion method

    Wang, Hanchen

    2016-09-06

    Using full waveform inversion (FWI) to locate microseismic and image microseismic events allows for an automatic process (free of picking) that utilizes the full wavefield. However, waveform inversion of microseismic events faces incredible nonlinearity due to the unknown source location (space) and function (time). We develop a source independent FWI of microseismic events to invert for the source image, source function and the velocity model. It is based on convolving reference traces with the observed and modeled data to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. The extended image for source wavelet in z axis is extracted to check the accuracy of the inverted source image and velocity model. Also the angle gather is calculated to see if the velocity model is correct. By inverting for all the source image, source wavelet and the velocity model, the proposed method produces good estimates of the source location, ignition time and the background velocity for part of the SEG overthrust model.

  6. Microseismic imaging using a source-independent full-waveform inversion method

    Wang, Hanchen

    2016-01-01

    Using full waveform inversion (FWI) to locate microseismic and image microseismic events allows for an automatic process (free of picking) that utilizes the full wavefield. However, waveform inversion of microseismic events faces incredible nonlinearity due to the unknown source location (space) and function (time). We develop a source independent FWI of microseismic events to invert for the source image, source function and the velocity model. It is based on convolving reference traces with the observed and modeled data to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. The extended image for source wavelet in z axis is extracted to check the accuracy of the inverted source image and velocity model. Also the angle gather is calculated to see if the velocity model is correct. By inverting for all the source image, source wavelet and the velocity model, the proposed method produces good estimates of the source location, ignition time and the background velocity for part of the SEG overthrust model.

  7. Characterization of high density SiPM non-linearity and energy resolution for prompt gamma imaging applications

    Regazzoni, V.; Acerbi, F.; Cozzi, G.; Ferri, A.; Fiorini, C.; Paternoster, G.; Piemonte, C.; Rucatti, D.; Zappalà, G.; Zorzi, N.; Gola, A.

    2017-07-01

    Fondazione Bruno Kessler (FBK) (Trento, Italy) has recently introduced High Density (HD) and Ultra High-Density (UHD) SiPMs, featuring very small micro-cell pitch. The high cell density is a very important factor to improve the linearity of the SiPM in high-dynamic-range applications, such as the scintillation light readout in high-energy gamma-ray spectroscopy and in prompt gamma imaging for proton therapy. The energy resolution at high energies is a trade-off between the excess noise factor caused by the non-linearity of the SiPM and the photon detection efficiency of the detector. To study these effects, we developed a new setup that simulates the LYSO light emission in response to gamma photons up to 30 MeV, using a pulsed light source. We measured the non-linearity and energy resolution vs. energy of the FBK RGB-HD e RGB-UHD SiPM technologies. We considered five different cell sizes, ranging from 10 μm up to 25 μm. With the UHD technology we were able to observe a remarkable reduction of the SiPM non-linearity, less than 5% at 5 MeV with 10 μm cells, which should be compared to a non-linearity of 50% with 25 μm-cell HD-SiPMs. With the same setup, we also measured the different components of the energy resolution (intrinsic, statistical, detector and electronic noise) vs. cell size, over-voltage and energy and we separated the different sources of excess noise factor.

  8. Adrenal imaging with technetium-99m-labelled low density lipoproteins

    Isaacsohn, J.L.; Lees, A.M.; Lees, R.S.; Strauss, H.W.; Barlai-Kovach, M.; Moore, T.J.

    1986-01-01

    Evaluation of adrenal cortical function by external imaging is currently accomplished by injection of radiolabelled analogs of cholesterol. Although the adrenals do utilized exogenous cholesterol for steroid hormone synthesis, the cholesterol is delivered to the glands not as free cholesterol but through the uptake of low density lipoproteins (LDL), which are subsequently degraded within the adrenal cortical cells to provide cholesterol. Thus, we sought to assess the use of /sup 99m/Tc-labelled LDL injected into rabbits to obtain external images of the adrenal glands. Adrenal images of all nine rabbits tested were obtained within 18 to 21 hours after injection of /sup 99m/Tc-LDL. Seven of the rabbits were subjected to adrenal cortical suppression with dexamethasone and then all nine rabbits were imaged a second time. In the untreated animals, visualization of the adrenal glands was accompanied by normal serum cortisol concentrations and accumulation of radiolabel in the adrenals, whereas in the dexamethasone-treated animals, lack of visualization of the adrenal glands was correlated with low serum cortisols, and greatly decreased accumulation of the radionuclide in the adrenals. These findings demonstrate for the first time that LDL, when labelled with /sup 99m/Tc, can be used to evaluate adrenal cortical function by external imaging

  9. Nonalcoholic fatty liver disease: MR imaging of liver proton density fat fraction to assess hepatic steatosis.

    Tang, An; Tan, Justin; Sun, Mark; Hamilton, Gavin; Bydder, Mark; Wolfson, Tanya; Gamst, Anthony C; Middleton, Michael; Brunt, Elizabeth M; Loomba, Rohit; Lavine, Joel E; Schwimmer, Jeffrey B; Sirlin, Claude B

    2013-05-01

    To evaluate the diagnostic performance of magnetic resonance (MR) imaging-estimated proton density fat fraction (PDFF) for assessing hepatic steatosis in nonalcoholic fatty liver disease (NAFLD) by using centrally scored histopathologic validation as the reference standard. This prospectively designed, cross-sectional, internal review board-approved, HIPAA-compliant study was conducted in 77 patients who had NAFLD and liver biopsy. MR imaging-PDFF was estimated from magnitude-based low flip angle multiecho gradient-recalled echo images after T2* correction and multifrequency fat modeling. Histopathologic scoring was obtained by consensus of the Nonalcoholic Steatohepatitis (NASH) Clinical Research Network Pathology Committee. Spearman correlation, additivity and variance stabilization for regression for exploring the effect of a number of potential confounders, and receiver operating characteristic analyses were performed. Liver MR imaging-PDFF was systematically higher, with higher histologic steatosis grade (P steatosis grade (ρ = 0.69, P steatosis grade 0 (n = 5) from those with grade 1 or higher (n = 72), 0.825 (95% confidence interval: 0.734, 0.915) to distinguish those with grade 1 or lower (n = 31) from those with grade 2 or higher (n = 46), and 0.893 (95% confidence interval: 0.809, 0.977) to distinguish those with grade 2 or lower (n = 58) from those with grade 3 (n = 19). MR imaging-PDFF showed promise for assessment of hepatic steatosis grade in patients with NAFLD. For validation, further studies with larger sample sizes are needed. © RSNA, 2013.

  10. Determination of CT number and density profile of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using computed tomography imaging and electron density phantom

    Yusof, Mohd Fahmi Mohd; Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz; Bauk, Sabar; Hashim, Rokiah

    2015-01-01

    Plug density phantoms were constructed in accordance to CT density phantom model 062M CIRS using binderless, pre-treated and tannin-based Rhizophora Spp. particleboards. The Rhizophora Spp. plug phantoms were scanned along with the CT density phantom using Siemens Somatom Definition AS CT scanner at three CT energies of 80, 120 and 140 kVp. 15 slices of images with 1.0 mm thickness each were taken from the central axis of CT density phantom for CT number and CT density profile analysis. The values were compared to water substitute plug phantom from the CT density phantom. The tannin-based Rhizophora Spp. gave the nearest value of CT number to water substitute at 80 and 120 kVp CT energies with χ 2 value of 0.011 and 0.014 respectively while the binderless Rhizphora Spp. gave the nearest CT number to water substitute at 140 kVp CT energy with χ 2 value of 0.023. The tannin-based Rhizophora Spp. gave the nearest CT density profile to water substitute at all CT energies. This study indicated the suitability of Rhizophora Spp. particleboard as phantom material for the use in CT imaging studies

  11. Determination of CT number and density profile of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using computed tomography imaging and electron density phantom

    Yusof, Mohd Fahmi Mohd, E-mail: mfahmi@usm.my; Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz [School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Bauk, Sabar [School of Distance Education, Universiti Sains Malaysia, 11800 Penang (Malaysia); Hashim, Rokiah [School of Industrial Technologies, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-04-29

    Plug density phantoms were constructed in accordance to CT density phantom model 062M CIRS using binderless, pre-treated and tannin-based Rhizophora Spp. particleboards. The Rhizophora Spp. plug phantoms were scanned along with the CT density phantom using Siemens Somatom Definition AS CT scanner at three CT energies of 80, 120 and 140 kVp. 15 slices of images with 1.0 mm thickness each were taken from the central axis of CT density phantom for CT number and CT density profile analysis. The values were compared to water substitute plug phantom from the CT density phantom. The tannin-based Rhizophora Spp. gave the nearest value of CT number to water substitute at 80 and 120 kVp CT energies with χ{sup 2} value of 0.011 and 0.014 respectively while the binderless Rhizphora Spp. gave the nearest CT number to water substitute at 140 kVp CT energy with χ{sup 2} value of 0.023. The tannin-based Rhizophora Spp. gave the nearest CT density profile to water substitute at all CT energies. This study indicated the suitability of Rhizophora Spp. particleboard as phantom material for the use in CT imaging studies.

  12. Acoustic noise reduction in T 1- and proton-density-weighted turbo spin-echo imaging.

    Ott, Martin; Blaimer, Martin; Breuer, Felix; Grodzki, David; Heismann, Björn; Jakob, Peter

    2016-02-01

    To reduce acoustic noise levels in T 1-weighted and proton-density-weighted turbo spin-echo (TSE) sequences, which typically reach acoustic noise levels up to 100 dB(A) in clinical practice. Five acoustic noise reduction strategies were combined: (1) gradient ramps and shapes were changed from trapezoidal to triangular, (2) variable-encoding-time imaging was implemented to relax the phase-encoding gradient timing, (3) RF pulses were adapted to avoid the need for reversing the polarity of the slice-rewinding gradient, (4) readout bandwidth was increased to provide more time for gradient activity on other axes, (5) the number of slices per TR was reduced to limit the total gradient activity per unit time. We evaluated the influence of each measure on the acoustic noise level, and conducted in vivo measurements on a healthy volunteer. Sound recordings were taken for comparison. An overall acoustic noise reduction of up to 16.8 dB(A) was obtained by the proposed strategies (1-4) and the acquisition of half the number of slices per TR only. Image quality in terms of SNR and CNR was found to be preserved. The proposed measures in this study allowed a threefold reduction in the acoustic perception of T 1-weighted and proton-density-weighted TSE sequences compared to a standard TSE-acquisition. This could be achieved without visible degradation of image quality, showing the potential to improve patient comfort and scan acceptability.

  13. Orange Recognition on Tree Using Image Processing Method Based on Lighting Density Pattern

    H. R Ahmadi

    2015-03-01

    Full Text Available Within the last few years, a new tendency has been created towards robotic harvesting of oranges and some of citrus fruits. The first step in robotic harvesting is accurate recognition and positioning of fruits. Detection through image processing by color cameras and computer is currently the most common method. Obviously, a harvesting robot faces with natural conditions and, therefore, detection must be done in various light conditions and environments. In this study, it was attempted to provide a suitable algorithm for recognizing the orange fruits on tree. In order to evaluate the proposed algorithm, 500 images were taken in different conditions of canopy, lighting and the distance to the tree. The algorithm included sub-routines for optimization, segmentation, size filtering, separation of fruits based on lighting density method and coordinates determination. In this study, MLP neural network (with 3 hidden layers was used for segmentation that was found to be successful with an accuracy of 88.2% in correct detection. As there exist a high percentage of the clustered oranges in images, any algorithm aiming to detect oranges on the trees successfully should offer a solution to separate these oranges first. A new method based on the light and shade density method was applied and evaluated in this research. Finally, the accuracies for differentiation and recognition were obtained to be 89.5% and 88.2%, respectively.

  14. Image Denoising via Bayesian Estimation of Statistical Parameter Using Generalized Gamma Density Prior in Gaussian Noise Model

    Kittisuwan, Pichid

    2015-03-01

    The application of image processing in industry has shown remarkable success over the last decade, for example, in security and telecommunication systems. The denoising of natural image corrupted by Gaussian noise is a classical problem in image processing. So, image denoising is an indispensable step during image processing. This paper is concerned with dual-tree complex wavelet-based image denoising using Bayesian techniques. One of the cruxes of the Bayesian image denoising algorithms is to estimate the statistical parameter of the image. Here, we employ maximum a posteriori (MAP) estimation to calculate local observed variance with generalized Gamma density prior for local observed variance and Laplacian or Gaussian distribution for noisy wavelet coefficients. Evidently, our selection of prior distribution is motivated by efficient and flexible properties of generalized Gamma density. The experimental results show that the proposed method yields good denoising results.

  15. Early effect of NEURAPAS® balance on current source density (CSD of human EEG

    Koch Klaus

    2011-08-01

    Full Text Available Abstract Psychiatric patients often suffer from stress, anxiety and depression. Various plant extracts are known to fight stress (valerian, anxiety (passion flower or depression (St. John's wort. NEURAPAS® balance is a mixture of these three extracts and has been designed to cover this complex of psychiatric conditions. The study was initiated to quantitatively assess the effect of this combination on brain electric activity. Method Quantitative electroencephalogram (EEG current source density (CSD recording from 16 healthy male and female human volunteers (average age 49 years was used in a randomized, placebo-controlled cross over study. Recordings were performed 0. 5, 1. 5, 3 and 4 hours after administration of the preparations under the conditions of 6 min eyes open and 5 min d2 concentration test, mathematical calculation test and memory test, respectively. All variables (electric power within 6 frequency ranges at 17 electrode positions were fed into a linear discriminant analysis (eyes open condition. In the presence of mental load these variables were used to construct brain maps of frequency changes. Results Under the condition of mental load, centro-parietal spectral power remained statistically significantly lower within alpha1, alpha2 and beta1 frequencies in the presence of verum in comparison to placebo. Discriminant analysis revealed a difference to placebo 3 and 4 hours after intake of 6 tablets of NEURAPAS® balance. Data location within the polydimensional space was projected into the area of the effects of sedative and anti-depressive reference drugs tested earlier under identical conditions. Results appeared closer to the effects of fluoxetine than to St. John's wort. Conclusions Analysis of the neurophysiological changes following the intake of NEURAPAS® balance revealed a similarity of frequency changes to those of calming and anti-depressive drugs on the EEG without impairment of cognition. Trial registration Clinical

  16. Status Epilepticus Induced Spontaneous Dentate Gyrus Spikes: In Vivo Current Source Density Analysis.

    Sean P Flynn

    Full Text Available The dentate gyrus is considered to function as an inhibitory gate limiting excitatory input to the hippocampus. Following status epilepticus (SE, this gating function is reduced and granule cells become hyper-excitable. Dentate spikes (DS are large amplitude potentials observed in the dentate gyrus (DG of normal animals. DS are associated with membrane depolarization of granule cells, increased activity of hilar interneurons and suppression of CA3 and CA1 pyramidal cell firing. Therefore, DS could act as an anti-excitatory mechanism. Because of the altered gating function of the dentate gyrus following SE, we sought to investigate how DS are affected following pilocarpine-induced SE. Two weeks following lithium-pilocarpine SE induction, hippocampal EEG was recorded in male Sprague-Dawley rats with 16-channel silicon probes under urethane anesthesia. Probes were placed dorso-ventrally to encompass either CA1-CA3 or CA1-DG layers. Large amplitude spikes were detected from EEG recordings and subject to current source density analysis. Probe placement was verified histologically to evaluate the anatomical localization of current sinks and the origin of DS. In 9 of 11 pilocarpine-treated animals and two controls, DS were confirmed with large current sinks in the molecular layer of the dentate gyrus. DS frequency was significantly increased in pilocarpine-treated animals compared to controls. Additionally, in pilocarpine-treated animals, DS displayed current sinks in the outer, middle and/or inner molecular layers. However, there was no difference in the frequency of events when comparing between layers. This suggests that following SE, DS can be generated by input from medial and lateral entorhinal cortex, or within the dentate gyrus. DS were associated with an increase in multiunit activity in the granule cell layer, but no change in CA1. These results suggest that following SE there is an increase in DS activity, potentially arising from

  17. Imaging human atherosclerosis with /sup 99m/Tc-labeled low density lipoproteins

    Lees, A.M.; Lees, R.S.; Schoen, F.J.; Isaacsohn, J.L.; Fischman, A.J.; McKusick, K.A.; Strauss, H.W.

    1988-01-01

    The feasibility of localizing human atherosclerotic plaques by gamma scintillation camera external imaging with technetium-99m-labeled low density lipoproteins (99mTc-LDL) was tested in 17 patients who had atherosclerosis. Imaging demonstrated focal accumulation of radiolabel consistent with 99mTc-LDL sequestration by plaques in the carotid, iliac, or femoral vessels of four patients 8 to 21 hours after intravenous injection of the radiopharmaceutical. Focal accumulation of 99mTc-LDL also appeared in the location of coronary lesions in four patients, but this accumulation could not be distinguished with certainty from residual blood pool radioactivity. When carotid endarterectomy specimens from six patients who received 99mTc-LDL 1 day before endarterectomy were examined, the specimens had focal accumulations of radiolabel, with two to four times greater radioactivity in some regions of each specimen than in others; this occurred whether or not the lesions were detected on the gamma camera images. Lesion composition may have determined whether accumulation was quantitatively sufficient to produce an external image. Histologically, the imaged carotid specimen had abundant foam cells and macrophages and poorly organized intramural blood consistent with a plaque hemorrhage; in contrast, nonimaged endarterectomy specimens were mature, fibrocalcific plaques. We conclude that: 1) 99mTc-LDL did accumulate in human atherosclerotic plaques; 2) in some patients, the accumulation of 99mTc-LDL was sufficient for detection by gamma camera imaging; 3) the amount of LDL that accumulated appeared to depend on lesion composition; and 4) the design of new radiopharmaceuticals with reduced residual blood pool activity relative to plaque accumulation should lead to improved external imaging of atherosclerosis

  18. Imaging of current density distributions with a Nb weak-link scanning nano-SQUID microscope

    Shibata, Yusuke; Nomura, Shintaro; Kashiwaya, Hiromi; Kashiwaya, Satoshi; Ishiguro, Ryosuke; Takayanagi, Hideaki

    2015-10-01

    Superconducting quantum interference devices (SQUIDs) are accepted as one of the highest magnetic field sensitive probes. There are increasing demands to image local magnetic fields to explore spin properties and current density distributions in a two-dimensional layer of semiconductors or superconductors. Nano-SQUIDs have recently attracting much interest for high spatial resolution measurements in nanometer-scale samples. Whereas weak-link Dayem Josephson junction nano-SQUIDs are suitable to miniaturization, hysteresis in current-voltage (I-V) characteristics that is often observed in Dayem Josephson junction is not desirable for a scanning microscope. Here we report on our development of a weak-link nano-SQUIDs scanning microscope with small hysteresis in I-V curve and on reconstructions of two-dimensional current density vector in two-dimensional electron gas from measured magnetic field.

  19. Using CTX Image Features to Predict HiRISE-Equivalent Rock Density

    Serrano, Navid; Huertas, Andres; McGuire, Patrick; Mayer, David; Ardvidson, Raymond

    2010-01-01

    Methods have been developed to quantitatively assess rock hazards at candidate landing sites with the aid of images from the HiRISE camera onboard NASA s Mars Reconnaissance Orbiter. HiRISE is able to resolve rocks as small as 1-m in diameter. Some sites of interest do not have adequate coverage with the highest resolution sensors and there is a need to infer relevant information (like site safety or underlying geomorphology). The proposed approach would make it possible to obtain rock density estimates at a level close to or equal to those obtained from high-resolution sensors where individual rocks are discernable.

  20. AUTOMATED ASSESSMENT OF EPIDERMAL THICKNESS AND VASCULAR DENSITY OF PORT WINE STAINS OCT IMAGE

    CHENGMING WANG

    2014-01-01

    Full Text Available Optical coherence tomography (OCT enables in vivo imaging of port wine stains (PWS lesions. The knowledge of vascular structure and epidermal thickness (ET of PWS may aid the objective diagnosis and optimal treatment. To obtain the structural parameters more rapidly and avoid user intervention, an automated algorithm of energy map is introduced based on intensity and edge information to extract the skin surface using dynamic programming method. Subsequently, an averaged A-scan analysis is performed to obtain the mean ET and the relative intensity of dermis indicating the corresponding vascular density. This approach is currently successfully applied in clinical diagnosis and shows promising guidance and assessment of PDT treatment.

  1. Use of imaging plates at near saturation for high energy density particles

    Tanimoto, Tsuyoshi; Ohta, Kazuhide; Habara, Hideaki; Kodama, Ryousuke; Tanaka, Kazuo A.; Yabuuchi, Toshinori; Tampo, Motonobu; Zheng Jian

    2008-01-01

    Since an imaging plate (IP) is sensitive to electron, ion, and x rays, it can be used as a detector for laser plasma experiment using ultraintense laser. Moreover, an IP has the advantageous features such as high sensitivity, wide dynamic range, and high spatial resolution. Even though IP itself has a considerable wide dynamic range up to 10 5 , the IP data have appeared often saturated at an IP reading device. We propose a reading technique by inserting optical density filters so that an apparently saturated IP data can be saved.

  2. A trial fabrication of activity standard surface sources and positional standard surface sources for an imaging plate system

    Sato, Yasushi; Hino, Yoshio; Yamada, Takahiro; Matsumoto, Mikio

    2003-01-01

    An imaging plate system can detect low level activity, but quantitative analysis is difficult because there are no adequate standard surface sources. A new fabrication method was developed for standard surface sources by printing on a sheet of paper using an ink-jet printer with inks in which a radioactive material was mixed. The fabricated standard surface sources had high uniformity, high positional resolution arbitrary shapes and a broad intensity range. The standard sources were used for measurement of surface activity as an application. (H. Yokoo)

  3. Study of optimal X-ray exposure conditions in consideration of bone mineral density. Relation between bone mineral density and image contrast

    Kondo, Yuji

    2003-01-01

    Bone mineral density (BMD) increases through infancy and adolescence, reaching a maximum at 20-30 years of age. Thereafter, BMD gradually decreases with age in both sexes. The image contrast of radiographs of bones varies with the change in BMD owing to the changes in the X-ray absorption of bone. The image contrast of bone generally is higher in the young adult than in the older adult. To examine the relation between BMD and image visibility, we carried out the following experiments. We measured the image contrast of radiographs of a lumbar vertebra phantom in which BMD was equivalent to the average BMD for each developmental period. We examined image visibility at various levels of imaging contrast using the Howlett chart. The results indicated that differences in BMD affect the image contrast of radiographs, and, consequently, image visibility. It was also found that image visibility in the young adult was higher than that in the older adult. The findings showed that, in digital radiography of young adults with high BMD, X-ray exposure can be decreased according the ratio of improvement in image visibility. (author)

  4. Enabling vendor independent photoacoustic imaging systems with asynchronous laser source

    Wu, Yixuan; Zhang, Haichong K.; Boctor, Emad M.

    2018-02-01

    Channel data acquisition, and synchronization between laser excitation and PA signal acquisition, are two fundamental hardware requirements for photoacoustic (PA) imaging. Unfortunately, however, neither is equipped by most clinical ultrasound scanners. Therefore, less economical specialized research platforms are used in general, which hinders a smooth clinical transition of PA imaging. In previous studies, we have proposed an algorithm to achieve PA imaging using ultrasound post-beamformed (USPB) RF data instead of channel data. This work focuses on enabling clinical ultrasound scanners to implement PA imaging, without requiring synchronization between the laser excitation and PA signal acquisition. Laser synchronization is inherently consisted of two aspects: frequency and phase information. We synchronize without communicating the laser and the ultrasound scanner by investigating USPB images of a point-target phantom in two steps. First, frequency information is estimated by solving a nonlinear optimization problem, under the assumption that the segmented wave-front can only be beamformed into a single spot when synchronization is achieved. Second, after making frequencies of two systems identical, phase delay is estimated by optimizing the image quality while varying phase value. The proposed method is validated through simulation, by manually adding both frequency and phase errors, then applying the proposed algorithm to correct errors and reconstruct PA images. Compared with the ground truth, simulation results indicate that the remaining errors in frequency correction and phase correction are 0.28% and 2.34%, respectively, which affirm the potential of overcoming hardware barriers on PA imaging through software solution.

  5. A simple algorithm for estimation of source-to-detector distance in Compton imaging

    Rawool-Sullivan, Mohini W.; Sullivan, John P.; Tornga, Shawn R.; Brumby, Steven P.

    2008-01-01

    Compton imaging is used to predict the location of gamma-emitting radiation sources. The X and Y coordinates of the source can be obtained using a back-projected image and a two-dimensional peak-finding algorithm. The emphasis of this work is to estimate the source-to-detector distance (Z). The algorithm presented uses the solid angle subtended by the reconstructed image at various source-to-detector distances. This algorithm was validated using both measured data from the prototype Compton imager (PCI) constructed at the Los Alamos National Laboratory and simulated data of the same imager. Results show this method can be applied successfully to estimate Z, and it provides a way of determining Z without prior knowledge of the source location. This method is faster than the methods that employ maximum likelihood method because it is based on simple back projections of Compton scatter data

  6. Feasibility study on X-ray source with pinhole imaging method

    Qiu Rui; Li Junli

    2007-01-01

    In order to verify the feasibility of study on X-ray source with pinhole imaging method, and optimize the design of X-ray pinhole imaging system, an X-ray pinhole imaging equipment was set up. The change of image due to the change of the position and intensity of X-ray source was estimated with mathematical method and validated with experiment. The results show that the change of the spot position and gray of the spot is linearly related with the change of the position and intensity of X-ray source, so it is feasible to study X-ray source with pinhole imaging method in this application. The results provide some references for the design of X-ray pinhole imaging system. (authors)

  7. VOLUME STUDY WITH HIGH DENSITY OF PARTICLES BASED ON CONTOUR AND CORRELATION IMAGE ANALYSIS

    Tatyana Yu. Nikolaeva

    2014-11-01

    Full Text Available The subject of study is the techniques of particle statistics evaluation, in particular, processing methods of particle images obtained by coherent illumination. This paper considers the problem of recognition and statistical accounting for individual images of small scattering particles in an arbitrary section of the volume in case of high concentrations. For automatic recognition of focused particles images, a special algorithm for statistical analysis based on contouring and thresholding was used. By means of the mathematical formalism of the scalar diffraction theory, coherent images of the particles formed by the optical system with high numerical aperture were simulated. Numerical testing of the method proposed for the cases of different concentrations and distributions of particles in the volume was performed. As a result, distributions of density and mass fraction of the particles were obtained, and the efficiency of the method in case of different concentrations of particles was evaluated. At high concentrations, the effect of coherent superposition of the particles from the adjacent planes strengthens, which makes it difficult to recognize images of particles using the algorithm considered in the paper. In this case, we propose to supplement the method with calculating the cross-correlation function of particle images from adjacent segments of the volume, and evaluating the ratio between the height of the correlation peak and the height of the function pedestal in the case of different distribution characters. The method of statistical accounting of particles considered in this paper is of practical importance in the study of volume with particles of different nature, for example, in problems of biology and oceanography. Effective work in the regime of high concentrations expands the limits of applicability of these methods for practically important cases and helps to optimize determination time of the distribution character and

  8. Construction of a voxel model from CT images with density derived from CT numbers

    Cheng Mengyun; Zeng Qin; Cao Ruifen; Li Gui; Zheng Huaqing; Huang Shanqing; Song Gang; Wu Yican

    2010-01-01

    The voxel models representing human anatomy have been developed to calculate dose distribution in human body, while the density is the most important physical property of voxel model. Traditionally, when creating the Monte Carlo input files, the average tissue parameters recommended in ICRP report were used to assign each voxel in the existing voxel models. However, as each tissue consists of many voxels in which voxels are different in their densities, the method of assigning average tissue parameters doesn't take account of the voxel's discrepancy, and can't represent human anatomy faithfully. To represent human anatomy more faithfully, a method was implemented to assign each voxel, the density of which was derived from CT number. In order to compare with the traditional method, we have constructed two models from a same cadaver specimen date set. A CT-based pelvic voxel model called Pelvis-CT model, was constructed, the densities of which were derived from the CT numbers. A color photograph-based pelvic voxel model called Pelvis-Photo model, was also constructed, the densities of which were taken from ICRP Publication. The CT images and color photographs were obtained from the same female cadaver specimen. The Pelvis-CT and Pelvis-Photo models were ported into Monte Carlo code MCNP to calculate the conversion coefficients from kerma free-in-air to absorbed dose for external monoenergetic photon beams with energies of 0.1, 1 and 10 MeV under anterior-posterior (AP) geometries. The results were compared with those of given in ICRP74. Differences of up to 50% were observed between conversion coefficients of Pelvis-CT and Pelvis-Photo models, moreover the discrepancies decreased for the photon beams with higher energies. The overall trend of conversion coefficients of the Pelvis-CT model were agreed well with that of ICRP74 data. (author)

  9. Population-based imaging biobanks as source of big data.

    Gatidis, Sergios; Heber, Sophia D; Storz, Corinna; Bamberg, Fabian

    2017-06-01

    Advances of computational sciences over the last decades have enabled the introduction of novel methodological approaches in biomedical research. Acquiring extensive and comprehensive data about a research subject and subsequently extracting significant information has opened new possibilities in gaining insight into biological and medical processes. This so-called big data approach has recently found entrance into medical imaging and numerous epidemiological studies have been implementing advanced imaging to identify imaging biomarkers that provide information about physiological processes, including normal development and aging but also on the development of pathological disease states. The purpose of this article is to present existing epidemiological imaging studies and to discuss opportunities, methodological and organizational aspects, and challenges that population imaging poses to the field of big data research.

  10. Imaging of fast-neutron sources using solid-state track-recorder pinhole radiography

    Ruddy, F.H.; Gold, R.; Roberts, J.H.; Kaiser, B.J.; Preston, C.C.

    1983-08-01

    Pinhole imaging methods are being developed and tested for potential future use in imaging the intense neutron source of the Fusion Materials Irradiation Test (FMIT) Facility. Previously reported, extensive calibration measurements of the proton, neutron, and alpha particle response characteristics of CR-39 polymer solid state track recorders (SSTRs) are being used to interpret the results of imaging experiments using both charged particle and neutron pinhole collimators. High resolution, neutron pinhole images of a 252 Cf source have been obtained in the form of neutron induced proton recoil tracks in CR-39 polymer SSTR. These imaging experiments are described as well as their potential future applications to FMIT

  11. Short-circuit current density imaging of crystalline silicon solar cells via lock-in thermography: Robustness and simplifications

    Fertig, Fabian; Greulich, Johannes; Rein, Stefan

    2014-01-01

    Spatially resolved determination of solar cell parameters is beneficial for loss analysis and optimization of conversion efficiency. One key parameter that has been challenging to access by an imaging technique on solar cell level is short-circuit current density. This work discusses the robustness of a recently suggested approach to determine short-circuit current density spatially resolved based on a series of lock-in thermography images and options for a simplified image acquisition procedure. For an accurate result, one or two emissivity-corrected illuminated lock-in thermography images and one dark lock-in thermography image have to be recorded. The dark lock-in thermography image can be omitted if local shunts are negligible. Furthermore, it is shown that omitting the correction of lock-in thermography images for local emissivity variations only leads to minor distortions for standard silicon solar cells. Hence, adequate acquisition of one image only is sufficient to generate a meaningful map of short-circuit current density. Beyond that, this work illustrates the underlying physics of the recently proposed method and demonstrates its robustness concerning varying excitation conditions and locally increased series resistance. Experimentally gained short-circuit current density images are validated for monochromatic illumination in comparison to the reference method of light-beam induced current

  12. Analytic sensing for multi-layer spherical models with application to EEG source imaging

    Kandaswamy, Djano; Blu, Thierry; Van De Ville, Dimitri

    2013-01-01

    Source imaging maps back boundary measurements to underlying generators within the domain; e. g., retrieving the parameters of the generating dipoles from electrical potential measurements on the scalp such as in electroencephalography (EEG). Fitting such a parametric source model is non-linear in the positions of the sources and renewed interest in mathematical imaging has led to several promising approaches. One important step in these methods is the application of a sensing principle that ...

  13. Micro-seismic imaging using a source function independent full waveform inversion method

    Wang, Hanchen; Alkhalifah, Tariq

    2018-03-01

    At the heart of micro-seismic event measurements is the task to estimate the location of the source micro-seismic events, as well as their ignition times. The accuracy of locating the sources is highly dependent on the velocity model. On the other hand, the conventional micro-seismic source locating methods require, in many cases manual picking of traveltime arrivals, which do not only lead to manual effort and human interaction, but also prone to errors. Using full waveform inversion (FWI) to locate and image micro-seismic events allows for an automatic process (free of picking) that utilizes the full wavefield. However, full waveform inversion of micro-seismic events faces incredible nonlinearity due to the unknown source locations (space) and functions (time). We developed a source function independent full waveform inversion of micro-seismic events to invert for the source image, source function and the velocity model. It is based on convolving reference traces with these observed and modeled to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. The extended image for the source wavelet in Z axis is extracted to check the accuracy of the inverted source image and velocity model. Also, angle gathers is calculated to assess the quality of the long wavelength component of the velocity model. By inverting for the source image, source wavelet and the velocity model simultaneously, the proposed method produces good estimates of the source location, ignition time and the background velocity for synthetic examples used here, like those corresponding to the Marmousi model and the SEG/EAGE overthrust model.

  14. Micro-seismic imaging using a source function independent full waveform inversion method

    Wang, Hanchen

    2018-03-26

    At the heart of micro-seismic event measurements is the task to estimate the location of the source micro-seismic events, as well as their ignition times. The accuracy of locating the sources is highly dependent on the velocity model. On the other hand, the conventional micro-seismic source locating methods require, in many cases manual picking of traveltime arrivals, which do not only lead to manual effort and human interaction, but also prone to errors. Using full waveform inversion (FWI) to locate and image micro-seismic events allows for an automatic process (free of picking) that utilizes the full wavefield. However, full waveform inversion of micro-seismic events faces incredible nonlinearity due to the unknown source locations (space) and functions (time). We developed a source function independent full waveform inversion of micro-seismic events to invert for the source image, source function and the velocity model. It is based on convolving reference traces with these observed and modeled to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. The extended image for the source wavelet in Z axis is extracted to check the accuracy of the inverted source image and velocity model. Also, angle gathers is calculated to assess the quality of the long wavelength component of the velocity model. By inverting for the source image, source wavelet and the velocity model simultaneously, the proposed method produces good estimates of the source location, ignition time and the background velocity for synthetic examples used here, like those corresponding to the Marmousi model and the SEG/EAGE overthrust model.

  15. Neurite density imaging versus imaging of microscopic anisotropy in diffusion MRI: A model comparison using spherical tensor encoding.

    Lampinen, Björn; Szczepankiewicz, Filip; Mårtensson, Johan; van Westen, Danielle; Sundgren, Pia C; Nilsson, Markus

    2017-02-15

    In diffusion MRI (dMRI), microscopic diffusion anisotropy can be obscured by orientation dispersion. Separation of these properties is of high importance, since it could allow dMRI to non-invasively probe elongated structures such as neurites (axons and dendrites). However, conventional dMRI, based on single diffusion encoding (SDE), entangles microscopic anisotropy and orientation dispersion with intra-voxel variance in isotropic diffusivity. SDE-based methods for estimating microscopic anisotropy, such as the neurite orientation dispersion and density imaging (NODDI) method, must thus rely on model assumptions to disentangle these features. An alternative approach is to directly quantify microscopic anisotropy by the use of variable shape of the b-tensor. Along those lines, we here present the 'constrained diffusional variance decomposition' (CODIVIDE) method, which jointly analyzes data acquired with diffusion encoding applied in a single direction at a time (linear tensor encoding, LTE) and in all directions (spherical tensor encoding, STE). We then contrast the two approaches by comparing neurite density estimated using NODDI with microscopic anisotropy estimated using CODIVIDE. Data were acquired in healthy volunteers and in glioma patients. NODDI and CODIVIDE differed the most in gray matter and in gliomas, where NODDI detected a neurite fraction higher than expected from the level of microscopic diffusion anisotropy found with CODIVIDE. The discrepancies could be explained by the NODDI tortuosity assumption, which enforces a connection between the neurite density and the mean diffusivity of tissue. Our results suggest that this assumption is invalid, which leads to a NODDI neurite density that is inconsistent between LTE and STE data. Using simulations, we demonstrate that the NODDI assumptions result in parameter bias that precludes the use of NODDI to map neurite density. With CODIVIDE, we found high levels of microscopic anisotropy in white matter

  16. Fiber density estimation from single q-shell diffusion imaging by tensor divergence.

    Reisert, Marco; Mader, Irina; Umarova, Roza; Maier, Simon; Tebartz van Elst, Ludger; Kiselev, Valerij G

    2013-08-15

    Diffusion-weighted magnetic resonance imaging provides information about the nerve fiber bundle geometry of the human brain. While the inference of the underlying fiber bundle orientation only requires single q-shell measurements, the absolute determination of their volume fractions is much more challenging with respect to measurement techniques and analysis. Unfortunately, the usually employed multi-compartment models cannot be applied to single q-shell measurements, because the compartment's diffusivities cannot be resolved. This work proposes an equation for fiber orientation densities that can infer the absolute fraction up to a global factor. This equation, which is inspired by the classical mass preservation law in fluid dynamics, expresses the fiber conservation associated with the assumption that fibers do not terminate in white matter. Simulations on synthetic phantoms show that the approach is able to derive the densities correctly for various configurations. Experiments with a pseudo ground truth phantom show that even for complex, brain-like geometries the method is able to infer the densities correctly. In-vivo results with 81 healthy volunteers are plausible and consistent. A group analysis with respect to age and gender show significant differences, such that the proposed maps can be used as a quantitative measure for group and longitudinal analysis. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Combined Source-Channel Coding of Images under Power and Bandwidth Constraints

    Fossorier Marc

    2007-01-01

    Full Text Available This paper proposes a framework for combined source-channel coding for a power and bandwidth constrained noisy channel. The framework is applied to progressive image transmission using constant envelope -ary phase shift key ( -PSK signaling over an additive white Gaussian noise channel. First, the framework is developed for uncoded -PSK signaling (with . Then, it is extended to include coded -PSK modulation using trellis coded modulation (TCM. An adaptive TCM system is also presented. Simulation results show that, depending on the constellation size, coded -PSK signaling performs 3.1 to 5.2 dB better than uncoded -PSK signaling. Finally, the performance of our combined source-channel coding scheme is investigated from the channel capacity point of view. Our framework is further extended to include powerful channel codes like turbo and low-density parity-check (LDPC codes. With these powerful codes, our proposed scheme performs about one dB away from the capacity-achieving SNR value of the QPSK channel.

  18. Combined Source-Channel Coding of Images under Power and Bandwidth Constraints

    Marc Fossorier

    2007-01-01

    Full Text Available This paper proposes a framework for combined source-channel coding for a power and bandwidth constrained noisy channel. The framework is applied to progressive image transmission using constant envelope M-ary phase shift key (M-PSK signaling over an additive white Gaussian noise channel. First, the framework is developed for uncoded M-PSK signaling (with M=2k. Then, it is extended to include coded M-PSK modulation using trellis coded modulation (TCM. An adaptive TCM system is also presented. Simulation results show that, depending on the constellation size, coded M-PSK signaling performs 3.1 to 5.2 dB better than uncoded M-PSK signaling. Finally, the performance of our combined source-channel coding scheme is investigated from the channel capacity point of view. Our framework is further extended to include powerful channel codes like turbo and low-density parity-check (LDPC codes. With these powerful codes, our proposed scheme performs about one dB away from the capacity-achieving SNR value of the QPSK channel.

  19. Electromagnetic diagnostics of ECR-Ion Sources plasmas: optical/X-ray imaging and spectroscopy

    Mascali, D.; Castro, G.; Altana, C.; Caliri, C.; Mazzaglia, M.; Romano, F. P.; Leone, F.; Musumarra, A.; Naselli, E.; Reitano, R.; Torrisi, G.; Celona, L.; Cosentino, L. G.; Giarrusso, M.; Gammino, S.

    2017-12-01

    Magnetoplasmas in ECR-Ion Sources are excited from gaseous elements or vapours by microwaves in the range 2.45-28 GHz via Electron Cyclotron Resonance. A B-minimum, magnetohydrodynamic stable configuration is used for trapping the plasma. The values of plasma density, temperature and confinement times are typically ne= 1011-1013 cm-3, 01 eVSilicon Drift detectors with high energy resolution of 125 eV at 5.9 keV have been used for the characterization of plasma emission at 02imaging in the optical range and spectroscopic measurements have been carried out. Relative abundances of H/H2 atoms/molecules in the plasmas have been measured for different values of neutral pressure, microwave power and magnetic field profile (they are critical for high-power proton sources).

  20. A low emittance and uniform density Cs+ source for heavy ion induction linacs

    Henestroza, E.; Eylon, S.

    1990-01-01

    A heavy-ion induction linac experiment (MBE-4) in progress at LBL is studying the transport and acceleration of space-charge-dominated beams in a long alternate gradient focusing channel. Recent studies of the transverse beam dynamics suggested that characteristics of the injector geometry were contributing to the normalized transverse emittance growth. Phase space and current density distribution measurements of the beam extracted from the injector revealed aberrations and a hollow density profile. Based on EGUN calculations the authors redesigned the 10 mA injector for MBE-4 by modifying the cathode: Pierce electrode and using a curved emitting surface. The simulation predicts an extracted beam with less aberrations and a flat density profile. A test stand was used to check the new design. The density profile has measured and found to be in agreement with the numerical simulation

  1. MR Imaging-based Estimation of Upper Motor Neuron Density in Patients with Amyotrophic Lateral Sclerosis: A Feasibility Study.

    Chen, Jacqueline; Kostenko, Volodymyr; Pioro, Erik P; Trapp, Bruce D

    2018-01-23

    Purpose To determine if magnetic resonance (MR) imaging metrics can estimate primary motor cortex (PMC) motor neuron (MN) density in patients with amyotrophic lateral sclerosis (ALS). Materials and Methods Between 2012 and 2014, in situ brain MR imaging was performed in 11 patients with ALS (age range, 35-81 years; seven women and four men) soon after death (mean, 5.5 hours after death; range, 3.2-9.6 hours). The brain was removed, right PMC (RPMC) was excised, and MN density was quantified. RPMC metrics (thickness, volume, and magnetization transfer ratio) were calculated from MR images. Regression modeling was used to estimate MN density by using RPMC and global MR imaging metrics (brain and tissue volumes); clinical variables were subsequently evaluated as additional estimators. Models were tested at in vivo MR imaging by using the same imaging protocol (six patients with ALS; age range, 54-66 years; three women and three men). Results RPMC mean MN density varied over a greater than threefold range across patients and was estimated by a linear function of normalized gray matter volume (adjusted R 2 = 0.51; P = .008; <10% error in most patients). When considering only sporadic ALS, a linear function of normalized RPMC and white matter volumes estimated MN density (adjusted R 2 = 0.98; P = .01; <10% error in all patients). In vivo data analyses detected decreases in MN density over time. Conclusion PMC mean MN density varies widely in end-stage ALS possibly because of disease heterogeneity. MN density can potentially be estimated by MR imaging metrics. © RSNA, 2018 Online supplemental material is available for this article.

  2. Image quality optimization and evaluation of linearly mixed images in dual-source, dual-energy CT

    Yu Lifeng; Primak, Andrew N.; Liu Xin; McCollough, Cynthia H.

    2009-01-01

    In dual-source dual-energy CT, the images reconstructed from the low- and high-energy scans (typically at 80 and 140 kV, respectively) can be mixed together to provide a single set of non-material-specific images for the purpose of routine diagnostic interpretation. Different from the material-specific information that may be obtained from the dual-energy scan data, the mixed images are created with the purpose of providing the interpreting physician a single set of images that have an appearance similar to that in single-energy images acquired at the same total radiation dose. In this work, the authors used a phantom study to evaluate the image quality of linearly mixed images in comparison to single-energy CT images, assuming the same total radiation dose and taking into account the effect of patient size and the dose partitioning between the low-and high-energy scans. The authors first developed a method to optimize the quality of the linearly mixed images such that the single-energy image quality was compared to the best-case image quality of the dual-energy mixed images. Compared to 80 kV single-energy images for the same radiation dose, the iodine CNR in dual-energy mixed images was worse for smaller phantom sizes. However, similar noise and similar or improved iodine CNR relative to 120 kV images could be achieved for dual-energy mixed images using the same total radiation dose over a wide range of patient sizes (up to 45 cm lateral thorax dimension). Thus, for adult CT practices, which primarily use 120 kV scanning, the use of dual-energy CT for the purpose of material-specific imaging can also produce a set of non-material-specific images for routine diagnostic interpretation that are of similar or improved quality relative to single-energy 120 kV scans.

  3. Fresnel zone plate imaging of a 252Cf spontaneous fission source

    Stalker, K.T.; Hessel, K.R.

    1976-11-01

    The feasibility of coded aperture imaging for nuclear fuel motion monitoring is shown using Cf 252 spontaneous fission source. The theory of coded aperture imaging for Fresnel zone plate apertures is presented and design considerations for zone plate construction are discussed. Actual images are obtained which demonstrate a transverse resolution of 1.7 mm and a tomographic resolution of 1.5 millimeters. The capability of obtaining images through 12.7 mm of stainless steel is also shown

  4. Combining image processing and modeling to generate traces of beta-strands from cryo-EM density images of beta-barrels.

    Si, Dong; He, Jing

    2014-01-01

    Electron cryo-microscopy (Cryo-EM) technique produces 3-dimensional (3D) density images of proteins. When resolution of the images is not high enough to resolve the molecular details, it is challenging for image processing methods to enhance the molecular features. β-barrel is a particular structure feature that is formed by multiple β-strands in a barrel shape. There is no existing method to derive β-strands from the 3D image of a β-barrel at medium resolutions. We propose a new method, StrandRoller, to generate a small set of possible β-traces from the density images at medium resolutions of 5-10Å. StrandRoller has been tested using eleven β-barrel images simulated to 10Å resolution and one image isolated from the experimentally derived cryo-EM density image at 6.7Å resolution. StrandRoller was able to detect 81.84% of the β-strands with an overall 1.5Å 2-way distance between the detected and the observed β-traces, if the best of fifteen detections is considered. Our results suggest that it is possible to derive a small set of possible β-traces from the β-barrel cryo-EM image at medium resolutions even when no separation of the β-strands is visible in the images.

  5. Association of age and macular pigment optical density using dual-wavelength autofluorescence imaging

    Lima VC

    2013-04-01

    after 60 years of age.Keywords: age, macular pigment optical density, dual-wavelength autofluorescence imaging, association

  6. Neutron Imaging at Compact Accelerator-Driven Neutron Sources in Japan

    Yoshiaki Kiyanagi

    2018-03-01

    Full Text Available Neutron imaging has been recognized to be very useful to investigate inside of materials and products that cannot be seen by X-ray. New imaging methods using the pulsed structure of neutron sources based on accelerators has been developed also at compact accelerator-driven neutron sources and opened new application fields in neutron imaging. The world’s first dedicated imaging instrument at pulsed neutron sources was constructed at J-PARC in Japan owing to the development of such new methods. Then, usefulness of the compact accelerator-driven neutron sources in neutron science was recognized and such facilities were newly constructed in Japan. Now, existing and new sources have been used for neutron imaging. Traditional imaging and newly developed pulsed neutron imaging such as Bragg edge transmission have been applied to various fields by using compact and large neutron facilities. Here, compact accelerator-driven neutron sources used for imaging in Japan are introduced and some of their activities are presented.

  7. Time dependence of the field energy densities surrounding sources: Application to scalar mesons near point sources and to electromagnetic fields near molecules

    Persico, F.; Power, E.A.

    1987-01-01

    The time dependence of the dressing-undressing process, i.e., the acquiring or losing by a source of a boson field intensity and hence of a field energy density in its neighborhood, is considered by examining some simple soluble models. First, the loss of the virtual field is followed in time when a point source is suddenly decoupled from a neutral scalar meson field. Second, an initially bare point source acquires a virtual meson cloud as the coupling is switched on. The third example is that of an initially bare molecule interacting with the vacuum of the electromagnetic field to acquire a virtual photon cloud. In all three cases the dressing-undressing is shown to take place within an expanding sphere of radius r = ct centered at the source. At each point in space the energy density tends, for large times, to that of the ground state of the total system. Differences in the time dependence of the dressing between the massive scalar field and the massless electromagnetic field are discussed. The results are also briefly discussed in the light of Feinberg's ideas on the nature of half-dressed states in quantum field theory

  8. Imaging spectroscopic analysis at the Advanced Light Source

    MacDowell, A. A.; Warwick, T.; Anders, S.; Lamble, G.M.; Martin, M.C.; McKinney, W.R.; Padmore, H.A.

    1999-01-01

    One of the major advances at the high brightness third generation synchrotrons is the dramatic improvement of imaging capability. There is a large multi-disciplinary effort underway at the ALS to develop imaging X-ray, UV and Infra-red spectroscopic analysis on a spatial scale from. a few microns to 10nm. These developments make use of light that varies in energy from 6meV to 15KeV. Imaging and spectroscopy are finding applications in surface science, bulk materials analysis, semiconductor structures, particulate contaminants, magnetic thin films, biology and environmental science. This article is an overview and status report from the developers of some of these techniques at the ALS. The following table lists all the currently available microscopes at the. ALS. This article will describe some of the microscopes and some of the early applications

  9. [A preliminary research on multi-source medical image fusion].

    Kang, Yuanyuan; Li, Bin; Tian, Lianfang; Mao, Zongyuan

    2009-04-01

    Multi-modal medical image fusion has important value in clinical diagnosis and treatment. In this paper, the multi-resolution analysis of Daubechies 9/7 Biorthogonal Wavelet Transform is introduced for anatomical and functional image fusion, then a new fusion algorithm with the combination of local standard deviation and energy as texture measurement is presented. At last, a set of quantitative evaluation criteria is given. Experiments show that both anatomical and metabolism information can be obtained effectively, and both the edge and texture features can be reserved successfully. The presented algorithm is more effective than the traditional algorithms.

  10. A New Measurement of the Stellar Mass Density at z~5: Implications for the Sources of Cosmic Reionization

    Stark, D. P.; Bunker, A. J.; Ellis, R. S.; Eyles, L. P.; Lacy, M.

    2007-04-01

    We present a new measurement of the integrated stellar mass per comoving volume at redshift 5 determined via spectral energy fitting drawn from a sample of 214 photometrically selected galaxies with z'850LPmasses for various subsamples for which reliable and unconfused Spitzer IRAC detections are available. A spectroscopic sample of 14 of the most luminous sources with z=4.92 provides a firm lower limit to the stellar mass density of 1×106 Msolar Mpc-3. Several galaxies in this subsample have masses of order 1011 Msolar, implying that significant earlier activity occurred in massive systems. We then consider a larger sample whose photometric redshifts in the publicly available GOODS-MUSIC catalog lie in the range 4.4MUSIC photometric redshifts, we check the accuracy of their photometry and explore the possibility of contamination by low-z galaxies and low-mass stars. After excising probable stellar contaminants and using the z'850LP-J color to exclude any remaining foreground red galaxies, we conclude that 196 sources are likely to be at z~=5. The implied mass density from the unconfused IRAC fraction of this sample, scaled to the total available, is 6×106 Msolar Mpc-3. We discuss the uncertainties, as well as the likelihood that we have underestimated the true mass density. By including fainter and quiescent sources, the total integrated density could be as high as 1×107 Msolar Mpc-3. Even accounting for 25% cosmic variance within a single GOODS field, such a high mass density only 1.2 Gyr after the big bang has interesting consequences for the implied past average star formation during the period when cosmic reionization is now thought to have taken place. Using the currently available (but highly uncertain) rate of decline in the star formation history over 5mass at z~=5 if we admit significant dust extinction at early times or extend the luminosity function to very faint limits. An interesting consequence of the latter possibility is an abundant population

  11. Suppression of high-density artefacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

    Baissalov, R.; Sandison, G.A.; Rewcastle, J.C. [Department of Medical Physics, Tom Baker Cancer Center, Calgary, Canada, T2N 4N2 2 Department of Physics and Astronomy, University of Calgary, Calgary T2N 2N4 (Canada); Donnelly, B.J. [Department of Surgery, Tom Baker Cancer Center, Calgary, Canada, T2N 4N2 4 Department of Surgery, Foothills Hospital, Calgary T2N 2T7 (Canada); Saliken, J.C. [Department of Surgery, Tom Baker Cancer Center, Calgary T2N 4N2 (Canada); Department of Diagnostic Imaging, Foothills Hospital, Calgary T2N 2T7 (Canada); McKinnon, J.G. [Department of Surgery, Foothills Hospital, Calgary T2N 2T7 (Canada); Muldrew, K. [Department of Surgery, Faculty of Medicine, University of Calgary, Calgary T2N 2T7 (Canada)

    2000-05-01

    Image guidance in cryotherapy is usually performed using ultrasound. Although not currently in routine clinical use, x-ray CT imaging is an alternative means of guidance that can display the full 3D structure of the iceball, including frozen and unfrozen regions. However, the quality of x-ray CT images is compromised by the presence of high-density streak artefacts. To suppress these artefacts we applied temporal digital subtraction (TDS). This TDS method has the added advantage of improving the grey-scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high-density artefacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced artefact content. Thus TDS can be used to significantly suppress or eliminate high-density CT streak artefacts without reducing the metallic content of the cryoprobes. In vivo study needs to be conducted to establish the utility of this TDS procedure for CT assisted prostate or liver cryotherapy. Applying TDS in x-ray CT guided cryotherapy will facilitate estimation of the number and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent. (author)

  12. Suppression of high-density artefacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

    Baissalov, R.; Sandison, G.A.; Rewcastle, J.C.; Donnelly, B.J.; Saliken, J.C.; McKinnon, J.G.; Muldrew, K.

    2000-01-01

    Image guidance in cryotherapy is usually performed using ultrasound. Although not currently in routine clinical use, x-ray CT imaging is an alternative means of guidance that can display the full 3D structure of the iceball, including frozen and unfrozen regions. However, the quality of x-ray CT images is compromised by the presence of high-density streak artefacts. To suppress these artefacts we applied temporal digital subtraction (TDS). This TDS method has the added advantage of improving the grey-scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high-density artefacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced artefact content. Thus TDS can be used to significantly suppress or eliminate high-density CT streak artefacts without reducing the metallic content of the cryoprobes. In vivo study needs to be conducted to establish the utility of this TDS procedure for CT assisted prostate or liver cryotherapy. Applying TDS in x-ray CT guided cryotherapy will facilitate estimation of the number and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent. (author)

  13. Quantitative phase imaging of living cells with a swept laser source

    Chen, Shichao; Zhu, Yizheng

    2016-03-01

    Digital holographic phase microscopy is a well-established quantitative phase imaging technique. However, interference artifacts from inside the system, typically induced by elements whose optical thickness are within the source coherence length, limit the imaging quality as well as sensitivity. In this paper, a swept laser source based technique is presented. Spectra acquired at a number of wavelengths, after Fourier Transform, can be used to identify the sources of the interference artifacts. With proper tuning of the optical pathlength difference between sample and reference arms, it is possible to avoid these artifacts and achieve sensitivity below 0.3nm. Performance of the proposed technique is examined in live cell imaging.

  14. Description and validation of a combination of acoustical radiosity and the image source method

    Marbjerg, Gerd Høy; Jeong, Cheol-Ho; Brunskog, Jonas

    2014-01-01

    A model that combines image source modelling and acoustical radiosity with complex boundary con- ditions, thus including phase shifts on reflection, has been developed. The model is denoted Phased Acoustical Radiosity and Image Source Model (PARISM). It has been developed in order to be able...... to model both specular and diffuse reflections with complex-valued acoustical descriptions of the surfaces. This paper mainly describes the combination of the two models and the implementation of the angle dependent surface descriptions both in the image source model and in acoustical radiosity...

  15. Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

    Sibeck, David G.; Allen, R.; Aryan, H.; Bodewits, D.; Brandt, P.; Branduardi-Raymont, G.; Brown, G.; Carter, J. A.; Collado-Vega, Y. M.; Collier, M. R.; Connor, H. K.; Cravens, T. E.; Ezoe, Y.; Fok, M.-C.; Galeazzi, M.; Gutynska, O.; Holmström, M.; Hsieh, S.-Y.; Ishikawa, K.; Koutroumpa, D.; Kuntz, K. D.; Leutenegger, M.; Miyoshi, Y.; Porter, F. S.; Purucker, M. E.; Read, A. M.; Raeder, J.; Robertson, I. P.; Samsonov, A. A.; Sembay, S.; Snowden, S. L.; Thomas, N. E.; von Steiger, R.; Walsh, B. M.; Wing, S.

    2018-06-01

    measurements rarely suffice to determine the global extent of these density structures or their global variation as a function of solar wind conditions, except in the form of empirical studies based on observations from many different times and solar wind conditions. Remote sensing observations provide global information about auroral ovals (FUV and hard X-ray), the terrestrial plasmasphere (EUV), and the terrestrial ring current (ENA). ENA instruments with low energy thresholds (˜1 keV) have recently been used to obtain important information concerning the magnetosheaths of Venus, Mars, and the Earth. Recent technological developments make these magnetosheaths valuable potential targets for high-cadence wide-field-of-view soft X-ray imagers. Section 2 describes proposed dayside interaction mechanisms, including reconnection, the Kelvin-Helmholtz instability, and other processes in greater detail with an emphasis on the plasma density structures that they generate. It focuses upon the questions that remain as yet unanswered, such as the significance of each proposed interaction mode, which can be determined from its occurrence pattern as a function of location and solar wind conditions. Section 3 outlines the physics underlying the charge exchange generation of soft X-rays. Section 4 lists the background sources (helium focusing cone, planetary, and cosmic) of soft X-rays from which the charge exchange emissions generated by solar wind exchange must be distinguished. With the help of simulations employing state-of-the-art magnetohydrodynamic models for the solar wind-magnetosphere interaction, models for Earth's exosphere, and knowledge concerning these background emissions, Sect. 5 demonstrates that boundaries and regions such as the bow shock, magnetosheath, magnetopause, and cusps can readily be identified in images of charge exchange emissions. Section 6 reviews observations by (generally narrow) field of view (FOV) astrophysical telescopes that confirm the presence of

  16. Obtaining source current density related to irregularly structured electromagnetic target field inside human body using hybrid inverse/FDTD method.

    Han, Jijun; Yang, Deqiang; Sun, Houjun; Xin, Sherman Xuegang

    2017-01-01

    Inverse method is inherently suitable for calculating the distribution of source current density related with an irregularly structured electromagnetic target field. However, the present form of inverse method cannot calculate complex field-tissue interactions. A novel hybrid inverse/finite-difference time domain (FDTD) method that can calculate the complex field-tissue interactions for the inverse design of source current density related with an irregularly structured electromagnetic target field is proposed. A Huygens' equivalent surface is established as a bridge to combine the inverse and FDTD method. Distribution of the radiofrequency (RF) magnetic field on the Huygens' equivalent surface is obtained using the FDTD method by considering the complex field-tissue interactions within the human body model. The obtained magnetic field distributed on the Huygens' equivalent surface is regarded as the next target. The current density on the designated source surface is derived using the inverse method. The homogeneity of target magnetic field and specific energy absorption rate are calculated to verify the proposed method.

  17. Defocusing effects of lensless ghost imaging and ghost diffraction with partially coherent sources

    Zhou, Shuang-Xi; Sheng, Wei; Bi, Yu-Bo; Luo, Chun-Ling

    2018-04-01

    The defocusing effect is inevitable and degrades the image quality in the conventional optical imaging process significantly due to the close confinement of the imaging lens. Based on classical optical coherent theory and linear algebra, we develop a unified formula to describe the defocusing effects of both lensless ghost imaging (LGI) and lensless ghost diffraction (LGD) systems with a partially coherent source. Numerical examples are given to illustrate the influence of defocusing length on the quality of LGI and LGD. We find that the defocusing effects of the test and reference paths in the LGI or LGD systems are entirely different, while the LGD system is more robust against defocusing than the LGI system. Specifically, we find that the imaging process for LGD systems can be viewed as pinhole imaging, which may find applications in ultra-short-wave band imaging without imaging lenses, e.g. x-ray diffraction and γ-ray imaging.

  18. Eurasian otter (Lutra lutra) density estimate based on radio tracking and other data sources

    Quaglietta, L.; Hájková, Petra; Mira, A.; Boitani, L.

    2015-01-01

    Roč. 60, č. 2 (2015), s. 127-137 ISSN 2199-2401 R&D Projects: GA AV ČR KJB600930804 Institutional support: RVO:68081766 Keywords : Lutra lutra * Density estimation * Edge effect * Known-to-be-alive * Linear habitats * Sampling scale Subject RIV: EG - Zoology

  19. Beam alignment based on two-dimensional power spectral density of a near-field image.

    Wang, Shenzhen; Yuan, Qiang; Zeng, Fa; Zhang, Xin; Zhao, Junpu; Li, Kehong; Zhang, Xiaolu; Xue, Qiao; Yang, Ying; Dai, Wanjun; Zhou, Wei; Wang, Yuanchen; Zheng, Kuixing; Su, Jingqin; Hu, Dongxia; Zhu, Qihua

    2017-10-30

    Beam alignment is crucial to high-power laser facilities and is used to adjust the laser beams quickly and accurately to meet stringent requirements of pointing and centering. In this paper, a novel alignment method is presented, which employs data processing of the two-dimensional power spectral density (2D-PSD) for a near-field image and resolves the beam pointing error relative to the spatial filter pinhole directly. Combining this with a near-field fiducial mark, the operation of beam alignment is achieved. It is experimentally demonstrated that this scheme realizes a far-field alignment precision of approximately 3% of the pinhole size. This scheme adopts only one near-field camera to construct the alignment system, which provides a simple, efficient, and low-cost way to align lasers.

  20. Computed tomography imaging for the characterisation of drugs with radiation density measurements and HU spectroscopy.

    Sieron, Dominik A; Steib, Moritz; Suter, Dominik; Obmann, Verena C; Huber, Adrian T; Ebner, Lukas; Inderbitzin, Daniel; Christe, Andreas

    2018-01-29

    To investigate the computed tomography (CT) density of frequently administered medications (1) for the better characterisation of substances on abdominal CT, (2) to allow radiologists to narrow down possibilities in the identification of hyperdense material in the bowel and (3) to provide forensic doctors with a tool to identify gastric contents before an autopsy. From the list of the local hospital pharmacy, the 50 most frequently used medications were identified and scanned twice with a 128 row CT scanner (Acquillion, Toshiba, Tokyo, Japan). The protocol comprised two tube voltages of 100 kVp and 120 kVp, with a tube current of 100 mAs, a collimation of 0.5 mm and a slice thickness of 0.5 mm. Two readers were asked to measure the density (in Hounsfield units) and the noise (standard deviation of the Hounsfield units) of each pill in the two scans (100/120 kVp). After 4 weeks, both readers repeated the measurements to test repeatability (intra-rater agreement). The behaviour of each pill in hydrochloric acid (pH 2) was examined and the dissolution time was determined. The most dense pill was Cordarone (7265 HU), and the least was Perenterol (529 HU), with an attenuation that was lower than fat density (standard deviation of pixel density (noise) reflects inhomogeneity of the pharmacological product, varying from 9 to 1592 HU among the different pills (at 120 kVp). The absolute average HU increase per pill when changing to lower voltage was 78 ± 253 HU, with a linear fitting line with a slope of 0.21 as a constant variable in the density spectroscopy. After 4 hours in hydrochloric acid, only six tablets were still intact, including Flagyl and Dafalgan. The intra- and inter-rater agreements for all measurements were nearly perfect, with a correlation coefficient r of ≥0.99 (p <0.0001). Our data suggest that measuring the attenuation of drugs on CT images, including the homogeneity, and applying CT spectroscopy can narrow down possible identities of the most

  1. OCCIPITAL SOURCES OF RESTING STATE ALPHA RHYTHMS ARE RELATED TO LOCAL GRAY MATTER DENSITY IN SUBJECTS WITH AMNESIC MILD COGNITIVE IMPAIRMENT AND ALZHEIMER’S DISEASE

    Claudio, Babiloni; Claudio, Del Percio; Marina, Boccardi; Roberta, Lizio; Susanna, Lopez; Filippo, Carducci; Nicola, Marzano; Andrea, Soricelli; Raffaele, Ferri; Ivano, Triggiani Antonio; Annapaola, Prestia; Serenella, Salinari; Rasser Paul, E; Erol, Basar; Francesco, Famà; Flavio, Nobili; Görsev, Yener; Durusu, Emek-Savaş Derya; Gesualdo, Loreto; Ciro, Mundi; Thompson Paul, M; Rossini Paolo, M.; Frisoni Giovanni, B

    2014-01-01

    Occipital sources of resting state electroencephalographic (EEG) alpha rhythms are abnormal, at the group level, in patients with amnesic mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Here we evaluated the hypothesis that amplitude of these occipital sources is related to neurodegeneration in occipital lobe as measured by magnetic resonance imaging (MRI). Resting-state eyes-closed EEG rhythms were recorded in 45 healthy elderly (Nold), 100 MCI, and 90 AD subjects. Neurodegeneration of occipital lobe was indexed by weighted averages of gray matter density (GMD), estimated from structural MRIs. EEG rhythms of interest were alpha 1 (8–10.5 Hz) and alpha 2 (10.5–13 Hz). EEG cortical sources were estimated by low resolution brain electromagnetic tomography (LORETA). Results showed a positive correlation between occipital GMD and amplitude of occipital alpha 1 sources in Nold, MCI and AD subjects as a whole group (r=0.3, p=0.000004, N=235). Furthermore, there was a positive correlation between amplitude of occipital alpha 1 sources and cognitive status as revealed by Mini Mental State Evaluation (MMSE) score across all subjects (r=0.38, p=0.000001, N=235). Finally, amplitude of occipital alpha 1 sources allowed a moderate classification of individual Nold and AD subjects (sensitivity: 87.8%; specificity: 66.7%; area under the Receiver Operating Characteristic (ROC) curve: 0.81). These results suggest that the amplitude of occipital sources of resting state alpha rhythms is related to AD neurodegeneration in occipital lobe along pathological aging. PMID:25442118

  2. Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

    Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

    2014-02-01

    Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

  3. Effect of the lead screen in the radiographic image using iridium 192 as a source

    Garate Rojas, M.

    1983-01-01

    It's presented the effect of the lead screen in the image obtained on an impressionable film used in industrial gammagraphy. The source used was Iridium 192 and the tests were simulated like a real inspection. (E.G.) [pt

  4. Development of Realistic Head Models for Electromagnetic Source Imaging of the Human Brain

    Akalin, Z

    2001-01-01

    In this work, a methodology is developed to solve the forward problem of electromagnetic source imaging using realistic head models, For this purpose, first segmentation of the 3 dimensional MR head...

  5. A Fieldable-Prototype Large-Area Gamma-ray Imager for Orphan Source Search

    Ziock, Klaus-Peter [ORNL; Fabris, Lorenzo [ORNL; Carr, Dennis [Lawrence Livermore National Laboratory (LLNL); Collins, Jeff [Lawrence Livermore National Laboratory (LLNL); Cunningham, Mark F [Lawrence Livermore National Laboratory (LLNL); Habte Ghebretatios, Frezghi [ORNL; Karnowski, Thomas Paul [ORNL; Marchant, William [University of California, Berkeley

    2008-01-01

    We have constructed a unique instrument for use in the search for orphan sources. The system uses gamma-ray imaging to "see through" the natural background variations that effectively limit the search range of normal devices to ~10 m. The imager is mounted in a 4.9- m-long trailer and can be towed by a large personal vehicle. Source locations are determined both in range and along the direction of travel as the vehicle moves. A fully inertial platform coupled to a Global Positioning System receiver is used to map the gamma-ray images onto overhead geospatial imagery. The resulting images provide precise source locations, allowing rapid follow-up work. The instrument simultaneously searches both sides of the street to a distance of 50 m (100-m swath) for milliCurieclass sources with near-perfect performance.

  6. Micro-seismic Imaging Using a Source Independent Waveform Inversion Method

    Wang, Hanchen

    2016-04-18

    Micro-seismology is attracting more and more attention in the exploration seismology community. The main goal in micro-seismic imaging is to find the source location and the ignition time in order to track the fracture expansion, which will help engineers monitor the reservoirs. Conventional imaging methods work fine in this field but there are many limitations such as manual picking, incorrect migration velocity and low signal to noise ratio (S/N). In traditional surface survey imaging, full waveform inversion (FWI) is widely used. The FWI method updates the velocity model by minimizing the misfit between the observed data and the predicted data. Using FWI to locate and image microseismic events allows for an automatic process (free of picking) that utilizes the full wavefield. Use the FWI technique, and overcomes the difficulties of manual pickings and incorrect velocity model for migration. However, the technique of waveform inversion of micro-seismic events faces its own problems. There is significant nonlinearity due to the unknown source location (space) and function (time). We have developed a source independent FWI of micro-seismic events to simultaneously invert for the source image, source function and velocity model. It is based on convolving reference traces with the observed and modeled data to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. To examine the accuracy of the inverted source image and velocity model the extended image for source wavelet in z-axis is extracted. Also the angle gather is calculated to check the applicability of the migration velocity. By inverting for the source image, source wavelet and the velocity model simultaneously, the proposed method produces good estimates of the source location, ignition time and the background velocity in the synthetic experiments with both parts of the Marmousi and the SEG

  7. Neurite orientation dispersion and density imaging in the substantia nigra in idiopathic Parkinson disease

    Kamagata, Koji; Suzuki, Michimasa; Hori, Masaaki; Kumamaru, Kanako K.; Aoki, Shigeki; Hatano, Taku; Okuzumi, Ayami; Motoi, Yumiko; Hattori, Nobutaka; Abe, Osamu; Shimoji, Keigo; Kamiya, Kouhei

    2016-01-01

    We used neurite orientation dispersion and density imaging (NODDI) to quantify changes in the substantia nigra pars compacta (SNpc) and striatum in Parkinson disease (PD). Diffusion-weighted magnetic resonance images were acquired from 58 PD patients and 36 age- and sex-matched controls. The intracellular volume fraction (Vic), orientation dispersion index (OD), and isotropic volume fraction (Viso) of the basal ganglia were compared between groups. Multivariate logistic regression analysis determined which diffusion parameters were independent predictors of PD. Receiver operating characteristic (ROC) analysis compared the diagnostic accuracies of the evaluated indices. Pearson coefficient analysis correlated each diffusional parameter with disease severity. Vic in the contralateral SNpc and putamen were significantly lower in PD patients than in healthy controls (P < 0.00058). Vic and OD in the SNpc and putamen showed significant negative correlations (P < 0.05) with disease severity. Multivariate logistic analysis revealed that Vic (P = 0.0000046) and mean diffusivity (P = 0.019) in the contralateral SNpc were the independent predictors of PD. In the ROC analysis, Vic in the contralateral SNpc showed the best diagnostic performance (mean cutoff, 0.62; sensitivity, 0.88; specificity, 0.83). NODDI is likely to be useful for diagnosing PD and assessing its progression. (orig.)

  8. [Magnetic resonance imaging. Density equalizing mapping analysis of global research architecture].

    Ohlendorf, D; Schwarze, B; Groneberg, D A; Schwarzer, M

    2015-09-01

    Despite the great medical importance, there is still no comprehensive scientometric analysis regarding the results of magnetic resonance imaging (MRI) and the development of the importance for the healthcare system. This paper evaluated and analyzed the entire research publication results on the topic of MRI for the period 1981-2007 based on scientometric methods and parameters. A scientometric analysis (database: ISI Web of Science 1981-2007, search terms MRI and magnetic resonance imaging) was performed. The following parameters were analyzed: number of publications, countries of publication, number of citations, citation rate and collaborations, using various analytical and display techniques, including density equalizing map projections. Most of the 49,122 publications on MRI could be attributed to the USA (32.5 %), which also has the most cooperative collaborations. Within Europe, Germany (10.3 %) is the country with the highest number of publications followed by the UK (9.3 %). The western industrialized nations dominate over the rest of the world in terms of scientific developments of MRI. The thematic focus of the publications lies in the fields of radiology and neuroscience. In addition to the journal Neurology most scientific articles were published in Magnetic Resonance in Medicine and Circulation. The results show that the current trend is continuing and the scientific interest in MRI is continuously increasing.

  9. Relationship between lens density measurements by Pentacam Scheimpflug imaging and torsional phacoemulsification parameters

    Suleyman Demircan

    2014-10-01

    Full Text Available AIM: To evaluate the relationship between the density values of the lens nucleus measured using Pentacam Scheimpflug imaging and torsional phacoemulsification dynamics such as the level of ultrasound energy, as well as the duration and amount of fluid used in patients with age-related nuclear cataract. METHODS: This was a prospective observer-masked study. Pentacam Scheimpflug imaging was performed following pupil dilation. The cataracts were automatically graded from 1 to 5 using pentacam nucleus densitometry(PND, also known as Pentacam nucleus staging(PNSsoftware by the same observer. After phacoemulsification, total Ultrasound(U/Stime, Cumulative dissipated energy(CDE, Torsional U/S time, and Estimated fluid use were automatically calculated and displayed on the monitor of Infiniti OZiL IP phacoemulsification system. One-way analysis of variance(ANOVAwas used to assess differences between groups. The Tamhane test was used for multiple group analysis. Spearman correlation analysis was used to assess the relationship between lens density measured by PND and the dynamics of torsional phacoemulsification. P0.05 was considered statistically significant. RESULTS:In the present study, 125 eyes from 125 patients were evaluated. Mean age was 69.7±9.4y(range: 48-88y, and 61 men and 64 women were included. The highest and lowest values of U/S total time, torsional U/S time, CDE, and Estimated fluid use were 0.70 - 158.90s, 0.70-158.50s, 0.11-42.65, and 21-98 mL in groups, respectively. Significant differences were found among PND groups. When the relationship between phacoemulsification dynamics and PND values were evaluated, there were significant correlations between PND value and total ultrasound time(r=0.767; Pr=0.767; Pr=0.758; Pr=0.602; PCONCLUSION:An objective degree of nucleus density obtained by PND scoring before cataract surgery may allow antecedent determination of intraoperative phacoemulsification parameters. Thus, individualized

  10. Charge modes of pulsed high energy and high density plasma injection source

    Cheng, D.Y.

    1974-01-01

    Detonation (snowplow), deflagration and other modes of discharge can be produced in a single coaxial plasma gun. Conservation laws of mass, momentum and energy together with the entropy production condition of the discharge phenomena are used to identify dense discharge modes. The Rankine-Hugoniot relation for a magnetized plasma is derived. Discussions of how to design a deflagration plasma gun to yield a prescribed plasma kinetic energy and plasma beam density are given

  11. A novel method for detecting light source for digital images forensic

    Roy, A. K.; Mitra, S. K.; Agrawal, R.

    2011-06-01

    Manipulation in image has been in practice since centuries. These manipulated images are intended to alter facts — facts of ethics, morality, politics, sex, celebrity or chaos. Image forensic science is used to detect these manipulations in a digital image. There are several standard ways to analyze an image for manipulation. Each one has some limitation. Also very rarely any method tried to capitalize on the way image was taken by the camera. We propose a new method that is based on light and its shade as light and shade are the fundamental input resources that may carry all the information of the image. The proposed method measures the direction of light source and uses the light based technique for identification of any intentional partial manipulation in the said digital image. The method is tested for known manipulated images to correctly identify the light sources. The light source of an image is measured in terms of angle. The experimental results show the robustness of the methodology.

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

    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.

  13. Three-dimensional density field determination by external stationary detectors and gamma sources using selective scattering

    Kondic, N.; Jacobs, A.; Ebert, D.

    1983-01-01

    In many fields one needs to know the spatial density distribution; two-phase systems are of particular importance. In particular, gas-liquid mixtures play a role in power generation, chemistry, bio-medicine etc. An intrusion into the measured system is frequently undesired or not permitted. Therefore, external, non-invasive instrumentation has definite advantages. Photon-energy discrimination methods, measuring scattered fluxes, can employ stationary equipment; they need partial collimation or only protective shielding. The results are achieved with a higher information/irradiation ratio than is the case with transmission methods. The utilization a mesh of isogonic lines (each of them being characterised by its particular scattering angle) has several advantages when compared with the mesh of straight lines (''pencil beams'') used in tomography. The ultimate experimental arrangement employing Compton scattering has fan/fan beam geometry, i.e., wide angle emitting and receiving of gammas. The direct result of the measurement is a ''scattergram'', i.e., countrate versus scattered energy spectrum. Besides representing the ''signature'' of a two- or three-dimensional density distribution, it also enables the reconstruction of local density values. The report outlines the necessary analysis and presents experimental proof of principle

  14. Microfocus x-ray imaging of traceable pointlike {sup 22}Na sources for quality control

    Hasegawa, T.; Oda, K.; Sato, Y.; Ito, H.; Masuda, S.; Yamada, T.; Matsumoto, M.; Murayama, H.; Takei, H. [Allied Health Sciences, Kitasato University Kitasato 1-15-1, Minami-ku, Sagamihara-shi, Kanagawa 252-0373 (Japan); Positron Medical Center, Tokyo Metropolitan Institute of Gerontology Sakaecho 35-2, Itabashi-ku, Tokyo 173-0015 (Japan); Advanced Industrial Science and Technology (AIST) Central 2, Umezono 1-1-1, Tsukuba-shi, Ibaraki 305-8568 (Japan); Kanagawa Industrial Technology Center (KITC) Shimoimazumi 705-1, Ebina-shi, Kanagawa 243-0435 (Japan); Japan Radioisotope Association (JRIA) Komagome 2-28-45, Bunkyo-ku, Tokyo 113-8941 (Japan); Molecular Imaging Center, National Institute of Radiological Sciences Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Graduate School of Medical Sciences, Kitasato University Kitasato 1-15-1, Minami-ku, Sagamihara-shi, Kanagawa 252-0373 (Japan)

    2012-07-15

    Purpose: The purpose of this study is to propose a microfocus x-ray imaging technique for observing the internal structure of small radioactive sources and evaluating geometrical errors quantitatively, and to apply this technique to traceable pointlike {sup 22}Na sources, which were designed for positron emission tomography calibration, for the purpose of quality control of the pointlike sources. Methods: A microfocus x-ray imaging system with a focus size of 0.001 mm was used to obtain projection x-ray images and x-ray CT images of five pointlike source samples, which were manufactured during 2009-2012. The obtained projection and tomographic images were used to observe the internal structure and evaluate geometrical errors quantitatively. Monte Carlo simulation was used to evaluate the effect of possible geometrical errors on the intensity and uniformity of 0.511 MeV annihilation photon pairs emitted from the sources. Results: Geometrical errors were evaluated with sufficient precision using projection x-ray images. CT images were used for observing the internal structure intuitively. As a result, four of the five examined samples were within the tolerance to maintain the total uncertainty below {+-}0.5%, given the source radioactivity; however, one sample was found to be defective. Conclusions: This quality control procedure is crucial and offers an important basis for using the pointlike {sup 22}Na source as a basic calibration tool. The microfocus x-ray imaging approach is a promising technique for visual and quantitative evaluation of the internal geometry of small radioactive sources.

  15. V-I curves and plasma parameters in a high density DC glow discharge generated by a current-source

    Granda-Gutierrez, E E; Lopez-Callejas, R; Piedad-Beneitez, A de la; BenItez-Read, J S; Pacheco-Sotelo, J O; Pena-Eguiluz, R; A, R Valencia; Mercado-Cabrera, A; Barocio, S R

    2008-01-01

    Nitrogen DC glow discharges, conducted in a cylindrical geometry, have been characterized using a new current-source able to provide 10 -3 - 3 A for the sustainment of the discharge, instead of a conventional voltage-source. The V-I characteristic curves obtained from these discharges were found to fit the general form i(v) = A(p)v k(p) , whereby the plasma itself can be modeled as a voltage-controlled current-source. We conclude that the fitting parameters A and k, which mainly depend on the gas pressure p, are strongly related to the plasma characteristics, so much so that they can indicate the pressure interval in which the maximum plasma density is located, with values in the order of 10 16 m -3 at reduced discharge potential (300-600 V) and low working pressure (10 -1 - 10 1 Pa)

  16. A paper sheet phantom for scintigraphic planar imaging. Usefulness of pouch-laminated paper source

    Takaki, Akihiro; Soma, Tsutomu; Murase, Kenya; Teraoka, Satomi; Murakami, Tomonori; Kojima, Akihiro; Matsumoto, Masanori

    2007-01-01

    In order to perform experimental measurements for evaluation of imaging device's performance, data acquisition technique, and clinical images on scintigraphic imaging, many kinds of phantoms are employed. However, since these materials are acrylic and plastic, the thickness and quality of those materials cause attenuation and scatter in itself. We developed a paper sheet phantom sealed with a pouch laminator, which can be a true radioactive source in air. In this study, the paper sheet phantom was compared to the acrylic liver phantom, with the thickness of 2 cm, which is commercially available. The results showed that although some scatter counts were contained within the image of the acrylic liver phantom, there were few scattered photons in the paper sheet phantom image. Furthermore, this laminated paper sheet phantom made handling of the source and its waste easier. If the paper sheet phantom will be designed more sophisticatedly, it becomes a useful tool for planar imaging experiments. (author)

  17. Online molecular image repository and analysis system: A multicenter collaborative open-source infrastructure for molecular imaging research and application.

    Rahman, Mahabubur; Watabe, Hiroshi

    2018-05-01

    Molecular imaging serves as an important tool for researchers and clinicians to visualize and investigate complex biochemical phenomena using specialized instruments; these instruments are either used individually or in combination with targeted imaging agents to obtain images related to specific diseases with high sensitivity, specificity, and signal-to-noise ratios. However, molecular imaging, which is a multidisciplinary research field, faces several challenges, including the integration of imaging informatics with bioinformatics and medical informatics, requirement of reliable and robust image analysis algorithms, effective quality control of imaging facilities, and those related to individualized disease mapping, data sharing, software architecture, and knowledge management. As a cost-effective and open-source approach to address these challenges related to molecular imaging, we develop a flexible, transparent, and secure infrastructure, named MIRA, which stands for Molecular Imaging Repository and Analysis, primarily using the Python programming language, and a MySQL relational database system deployed on a Linux server. MIRA is designed with a centralized image archiving infrastructure and information database so that a multicenter collaborative informatics platform can be built. The capability of dealing with metadata, image file format normalization, and storing and viewing different types of documents and multimedia files make MIRA considerably flexible. With features like logging, auditing, commenting, sharing, and searching, MIRA is useful as an Electronic Laboratory Notebook for effective knowledge management. In addition, the centralized approach for MIRA facilitates on-the-fly access to all its features remotely through any web browser. Furthermore, the open-source approach provides the opportunity for sustainable continued development. MIRA offers an infrastructure that can be used as cross-boundary collaborative MI research platform for the rapid

  18. Polarization effect of CdZnTe imaging detector based on high energy γ source

    Li Miao; Xiao Shali; Wang Xi; Shen Min; Zhang Liuqiang; Cao Yulin; Chen Yuxiao

    2011-01-01

    The inner electric potential distribution of CdZnTe detector was derived by applying poisson equation with the first type boundary condition, and the polarization effect of CdZnTe pixellated detector for imaging 137 Cs γ source was investigated. The results of numerical calculation and experiment indicate that electric potential distribution is mainly influenced by applied bias for low charge density in CdZnTe crystal and, in turn, there is linear relationship between electric potential distribution and applied bias that induces uniform electric field under low irradiated flux. However, the electric potential appears polarization phenomenon, and the electric field in CdZnTe crystal is distorted when CdZnTe detector is under high irradiated flux. Consequently, charge carriers in CdZnTe crystal drift towards the edge pixels of irradiated region, and hence, the shut-off central pixels are surrounded by a ring of low counting pixels. The polarization effect indeed deteriorates the performance of CdZnTe detector severely and the event counts of edge pixels for irradiated region reduce about 70%. (authors)

  19. Large seismic source imaging from old analogue seismograms

    Caldeira, Bento; Buforn, Elisa; Borges, José; Bezzeghoud, Mourad

    2017-04-01

    In this work we present a procedure to recover the ground motions by a proper digital structure, from old seismograms in analogue physical support (paper or microfilm) to study the source rupture process, by application of modern finite source inversion tools. Despite the quality that the analog data and the digitizing technologies available may have, recover the ground motions with the accurate metrics from old seismograms, is often an intricate procedure. Frequently the general parameters of the analogue instruments response that allow recover the shape of the ground motions (free periods and damping) are known, but the magnification that allow recover the metric of these motions is dubious. It is in these situations that the procedure applies. The procedure is based on assign of the moment magnitude value to the integral of the apparent Source Time Function (STF), estimated by deconvolution of a synthetic elementary seismogram from the related observed seismogram, corrected with an instrument response affected by improper magnification. Two delicate issues in the process are 1) the calculus of the synthetic elementary seismograms that must consider later phases if applied to large earthquakes (the portions of signal should be 3 or 4 times larger than the rupture time) and 2) the deconvolution to calculate the apparent STF. In present version of the procedure was used the Direct Solution Method to compute the elementary seismograms and the deconvolution was processed in time domain by an iterative algorithm that allow constrains the STF to stay positive and time limited. The method was examined using synthetic data to test the accuracy and robustness. Finally, a set of 17 real old analog seismograms from the Santa Maria (Azores) 1939 earthquake (Mw=7.1) was used in order to recover the waveforms in the required digital structure, from which by inversion allows compute the finite source rupture model (slip distribution). Acknowledgements: This work is co

  20. Localization of sources of the hyperinsulinism through the image methods

    Abath, C.G.A.

    1990-01-01

    Pancreatic insulinomas are small tumours, manifested early by the high hormonal production. Microscopic changes, like islet cell hyperplasia or nesidioblastosis, are also sources of hyperinsulinism. The pre-operative localization of the lesions is important, avoiding unnecessary or insufficient blind pancreatectomies. It is presented the experience with 26 patients with hyperinsulinism, of whom six were examined by ultrasound, nine by computed tomography, 25 by angiography and 16 by pancreatic venous sampling for hormone assay, in order to localize the lesions. Percutaneous transhepatic portal and pancreatic vein catheterization with measurement of insuline concentrations was the most reliable and sensitive method for detecting the lesions, including those non-palpable during the surgical exploration (author)

  1. Robust Estimation of Electron Density From Anatomic Magnetic Resonance Imaging of the Brain Using a Unifying Multi-Atlas Approach

    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.

  2. Energy source perceptions and policy support: Image associations, emotional evaluations, and cognitive beliefs

    Barnes Truelove, Heather

    2012-01-01

    This paper represents the most in-depth effort conducted to date to assess affective, emotional and cognitive perceptions of coal, natural gas, nuclear, and wind energy and the relationship between these perceptions and support for the energy sources. U.S. residents, recruited from a consumer panel, completed surveys assessing image associations, emotional reactions, and cognitive beliefs about energy sources and support for increased reliance on energy sources and local siting of energy facilities. The content of images produced by participants when evaluating energy sources revealed several interesting findings. Additionally, analysis of the image evaluations, emotions, and beliefs about each energy source showed that coal and nuclear energy were viewed most negatively, with natural gas in the middle, and wind viewed most positively. Importantly, these affective, emotional, and cognitive perceptions explained significant amounts of variance in support for each of the energy sources. Implications for future researchers and policy makers are discussed. - Highlights: ► Image associations, emotions, and beliefs about energy sources were measured. ► A dual-process model of energy support was proposed and tested. ► Coal and nuclear were viewed most negatively and wind was viewed most positively. ► The cognitive-affective model predicted support for each energy source.

  3. An open-source framework for analyzing N-electron dynamics. II. Hybrid density functional theory/configuration interaction methodology.

    Hermann, Gunter; Pohl, Vincent; Tremblay, Jean Christophe

    2017-10-30

    In this contribution, we extend our framework for analyzing and visualizing correlated many-electron dynamics to non-variational, highly scalable electronic structure method. Specifically, an explicitly time-dependent electronic wave packet is written as a linear combination of N-electron wave functions at the configuration interaction singles (CIS) level, which are obtained from a reference time-dependent density functional theory (TDDFT) calculation. The procedure is implemented in the open-source Python program detCI@ORBKIT, which extends the capabilities of our recently published post-processing toolbox (Hermann et al., J. Comput. Chem. 2016, 37, 1511). From the output of standard quantum chemistry packages using atom-centered Gaussian-type basis functions, the framework exploits the multideterminental structure of the hybrid TDDFT/CIS wave packet to compute fundamental one-electron quantities such as difference electronic densities, transient electronic flux densities, and transition dipole moments. The hybrid scheme is benchmarked against wave function data for the laser-driven state selective excitation in LiH. It is shown that all features of the electron dynamics are in good quantitative agreement with the higher-level method provided a judicious choice of functional is made. Broadband excitation of a medium-sized organic chromophore further demonstrates the scalability of the method. In addition, the time-dependent flux densities unravel the mechanistic details of the simulated charge migration process at a glance. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  4. Free and open source software for the manipulation of digital images.

    Solomon, Robert W

    2009-06-01

    Free and open source software is a type of software that is nearly as powerful as commercial software but is freely downloadable. This software can do almost everything that the expensive programs can. GIMP (gnu image manipulation program) is the free program that is comparable to Photoshop, and versions are available for Windows, Macintosh, and Linux platforms. This article briefly describes how GIMP can be installed and used to manipulate radiology images. It is no longer necessary to budget large amounts of money for high-quality software to achieve the goals of image processing and document creation because free and open source software is available for the user to download at will.

  5. Screen-detected versus interval cancers: Effect of imaging modality and breast density in the Flemish Breast Cancer Screening Programme.

    Timmermans, Lore; Bleyen, Luc; Bacher, Klaus; Van Herck, Koen; Lemmens, Kim; Van Ongeval, Chantal; Van Steen, Andre; Martens, Patrick; De Brabander, Isabel; Goossens, Mathieu; Thierens, Hubert

    2017-09-01

    To investigate if direct radiography (DR) performs better than screen-film mammography (SF) and computed radiography (CR) in dense breasts in a decentralized organised Breast Cancer Screening Programme. To this end, screen-detected versus interval cancers were studied in different BI-RADS density classes for these imaging modalities. The study cohort consisted of 351,532 women who participated in the Flemish Breast Cancer Screening Programme in 2009 and 2010. Information on screen-detected and interval cancers, breast density scores of radiologist second readers, and imaging modality was obtained by linkage of the databases of the Centre of Cancer Detection and the Belgian Cancer Registry. Overall, 67% of occurring breast cancers are screen detected and 33% are interval cancers, with DR performing better than SF and CR. The interval cancer rate increases gradually with breast density, regardless of modality. In the high-density class, the interval cancer rate exceeds the cancer detection rate for SF and CR, but not for DR. DR is superior to SF and CR with respect to cancer detection rates for high-density breasts. To reduce the high interval cancer rate in dense breasts, use of an additional imaging technique in screening can be taken into consideration. • Interval cancer rate increases gradually with breast density, regardless of modality. • Cancer detection rate in high-density breasts is superior in DR. • IC rate exceeds CDR for SF and CR in high-density breasts. • DR performs better in high-density breasts for third readings and false-positives.

  6. Column Number Density Expressions Through M = 0 and M = 1 Point Source Plumes Along Any Straight Path

    Woronowicz, Michael

    2016-01-01

    Analytical expressions for column number density (CND) are developed for optical line of sight paths through a variety of steady free molecule point source models including directionally-constrained effusion (Mach number M = 0) and flow from a sonic orifice (M = 1). Sonic orifice solutions are approximate, developed using a fair simulacrum fitted to the free molecule solution. Expressions are also developed for a spherically-symmetric thermal expansion (M = 0). CND solutions are found for the most general paths relative to these sources and briefly explored. It is determined that the maximum CND from a distant location through directed effusion and sonic orifice cases occurs along the path parallel to the source plane that intersects the plume axis. For the effusive case this value is exactly twice the CND found along the ray originating from that point of intersection and extending to infinity along the plume's axis. For sonic plumes this ratio is reduced to about 4/3. For high Mach number cases the maximum CND will be found along the axial centerline path. Keywords: column number density, plume flows, outgassing, free molecule flow.

  7. Battery-powered pulsed high density inductively coupled plasma source for pre-ionization in laboratory astrophysics experiments.

    Chaplin, Vernon H; Bellan, Paul M

    2015-07-01

    An electrically floating radiofrequency (RF) pre-ionization plasma source has been developed to enable neutral gas breakdown at lower pressures and to access new experimental regimes in the Caltech laboratory astrophysics experiments. The source uses a customized 13.56 MHz class D RF power amplifier that is powered by AA batteries, allowing it to safely float at 3-6 kV with the electrodes of the high voltage pulsed power experiments. The amplifier, which is capable of 3 kW output power in pulsed (<1 ms) operation, couples electrical energy to the plasma through an antenna external to the 1.1 cm radius discharge tube. By comparing the predictions of a global equilibrium discharge model with the measured scalings of plasma density with RF power input and axial magnetic field strength, we demonstrate that inductive coupling (rather than capacitive coupling or wave damping) is the dominant energy transfer mechanism. Peak ion densities exceeding 5 × 10(19) m(-3) in argon gas at 30 mTorr have been achieved with and without a background field. Installation of the pre-ionization source on a magnetohydrodynamically driven jet experiment reduced the breakdown time and jitter and allowed for the creation of hotter, faster argon plasma jets than was previously possible.

  8. A compact hard X-ray source for medical imaging and biomolecular studies

    Cline, D.B.; Green, M.A.; Kolonko, J.

    1995-01-01

    There are a large number of synchrotron light sources in the world. However, these sources are designed for physics, chemistry, and engineering studies. To our knowledge, none have been optimized for either medical imaging or biomolecular studies. There are special needs for these applications. We present here a preliminary design of a very compact source, small enough for a hospital or a biomolecular laboratory, that is suitable for these applications. (orig.)

  9. Upgraded millimeter-wave interferometer for measuring the electron density during the beam extraction in the negative ion source

    Tokuzawa, T., E-mail: tokuzawa@nifs.ac.jp; Kisaki, M.; Nagaoka, K.; Ito, Y.; Ikeda, K.; Nakano, H. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Tsumori, K.; Osakabe, M.; Takeiri, Y. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); The Graduate University for Advanced Studies, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Kaneko, O. [National Institutes of Natural Sciences, 4-3-13 Toranomon, Minato-ku, Tokyo 105-0001 (Japan)

    2016-11-15

    The upgraded millimeter-wave interferometer with the frequency of 70 GHz is installed on a large-scaled negative ion source. Measurable line-averaged electron density is from 2 × 10{sup 15} to 3 × 10{sup 18} m{sup −3} in front of the plasma grid. Several improvements such as the change to shorter wavelength probing with low noise, the installation of special ordered horn antenna, the signal modulation for a high accuracy digital phase detection, the insertion of insulator, and so on, are carried out for the measurement during the beam extraction by applying high voltage. The line-averaged electron density is successfully measured and it is found that it increases linearly with the arc power and drops suddenly at the beam extraction.

  10. On the Feasibility of Very-Low-Density Pure Metal Foams as Bright High-Energy X-ray Sources

    Colvin, Jeffrey; Felter, Thomas

    2003-10-01

    We have used the Busquet approximation (M. Busquet, Phys. Fluids B 5(11), 4191 (1993)) to explore calculationally what the possible x-ray conversion efficiencies into the K-band would be from irradiating very-low-density pure metal foams with tens of kilojoules of 1/3-micron laser light. We will discuss the advantages of pure metal foams as bright high-energy x-ray sources, and some results of this calculational study. We will also present our ideas for how to fabricate pure metal foams with densities of a few milligrams per cubic centimeter. This work was performed under the auspices of the US Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  11. Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

    Kim, Joshua; Zhang, Tiezhi; Lu, Weiguo

    2014-01-01

    Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source–dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10–15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source–dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented. (paper)

  12. Combining inter-source seismic interferometry and source-receiver interferometry for deep local imaging

    Liu, Y.; Arntsen, B.; Wapenaar, C.P.A.; Van der Neut, J.R.

    2014-01-01

    The virtual source method has been applied successfully to retrieve the impulse response between pairs of receivers in the subsurface. This method is further improved by an updown separation prior to the crosscorrelation to suppress the reflections from the overburden and the free surface. In a

  13. Hard X-Ray Flare Source Sizes Measured with the Ramaty High Energy Solar Spectroscopic Imager

    Dennis, Brian R.; Pernak, Rick L.

    2009-01-01

    Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observations of 18 double hard X-ray sources seen at energies above 25 keV are analyzed to determine the spatial extent of the most compact structures evident in each case. The following four image reconstruction algorithms were used: Clean, Pixon, and two routines using visibilities maximum entropy and forward fit (VFF). All have been adapted for this study to optimize their ability to provide reliable estimates of the sizes of the more compact sources. The source fluxes, sizes, and morphologies obtained with each method are cross-correlated and the similarities and disagreements are discussed. The full width at half-maximum (FWHM) of the major axes of the sources with assumed elliptical Gaussian shapes are generally well correlated between the four image reconstruction routines and vary between the RHESSI resolution limit of approximately 2" up to approximately 20" with most below 10". The FWHM of the minor axes are generally at or just above the RHESSI limit and hence should be considered as unresolved in most cases. The orientation angles of the elliptical sources are also well correlated. These results suggest that the elongated sources are generally aligned along a flare ribbon with the minor axis perpendicular to the ribbon. This is verified for the one flare in our list with coincident Transition Region and Coronal Explorer (TRACE) images. There is evidence for significant extra flux in many of the flares in addition to the two identified compact sources, thus rendering the VFF assumption of just two Gaussians inadequate. A more realistic approximation in many cases would be of two line sources with unresolved widths. Recommendations are given for optimizing the RHESSI imaging reconstruction process to ensure that the finest possible details of the source morphology become evident and that reliable estimates can be made of the source dimensions.

  14. Vertebral Body Compression Fractures and Bone Density: Automated Detection and Classification on CT Images.

    Burns, Joseph E; Yao, Jianhua; Summers, Ronald M

    2017-09-01

    Purpose To create and validate a computer system with which to detect, localize, and classify compression fractures and measure bone density of thoracic and lumbar vertebral bodies on computed tomographic (CT) images. Materials and Methods Institutional review board approval was obtained, and informed consent was waived in this HIPAA-compliant retrospective study. A CT study set of 150 patients (mean age, 73 years; age range, 55-96 years; 92 women, 58 men) with (n = 75) and without (n = 75) compression fractures was assembled. All case patients were age and sex matched with control subjects. A total of 210 thoracic and lumbar vertebrae showed compression fractures and were electronically marked and classified by a radiologist. Prototype fully automated spinal segmentation and fracture detection software were then used to analyze the study set. System performance was evaluated with free-response receiver operating characteristic analysis. Results Sensitivity for detection or localization of compression fractures was 95.7% (201 of 210; 95% confidence interval [CI]: 87.0%, 98.9%), with a false-positive rate of 0.29 per patient. Additionally, sensitivity was 98.7% and specificity was 77.3% at case-based receiver operating characteristic curve analysis. Accuracy for classification by Genant type (anterior, middle, or posterior height loss) was 0.95 (107 of 113; 95% CI: 0.89, 0.98), with weighted κ of 0.90 (95% CI: 0.81, 0.99). Accuracy for categorization by Genant height loss grade was 0.68 (77 of 113; 95% CI: 0.59, 0.76), with a weighted κ of 0.59 (95% CI: 0.47, 0.71). The average bone attenuation for T12-L4 vertebrae was 146 HU ± 29 (standard deviation) in case patients and 173 HU ± 42 in control patients; this difference was statistically significant (P high sensitivity and with a low false-positive rate, as well as to calculate vertebral bone density, on CT images. © RSNA, 2017 Online supplemental material is available for this article.

  15. Algorithms for biomagnetic source imaging with prior anatomical and physiological information

    Hughett, Paul William [Univ. of California, Berkeley, CA (United States). Dept. of Electrical Engineering and Computer Sciences

    1995-12-01

    This dissertation derives a new method for estimating current source amplitudes in the brain and heart from external magnetic field measurements and prior knowledge about the probable source positions and amplitudes. The minimum mean square error estimator for the linear inverse problem with statistical prior information was derived and is called the optimal constrained linear inverse method (OCLIM). OCLIM includes as special cases the Shim-Cho weighted pseudoinverse and Wiener estimators but allows more general priors and thus reduces the reconstruction error. Efficient algorithms were developed to compute the OCLIM estimate for instantaneous or time series data. The method was tested in a simulated neuromagnetic imaging problem with five simultaneously active sources on a grid of 387 possible source locations; all five sources were resolved, even though the true sources were not exactly at the modeled source positions and the true source statistics differed from the assumed statistics.

  16. Research on multi-source image fusion technology in haze environment

    Ma, GuoDong; Piao, Yan; Li, Bing

    2017-11-01

    In the haze environment, the visible image collected by a single sensor can express the details of the shape, color and texture of the target very well, but because of the haze, the sharpness is low and some of the target subjects are lost; Because of the expression of thermal radiation and strong penetration ability, infrared image collected by a single sensor can clearly express the target subject, but it will lose detail information. Therefore, the multi-source image fusion method is proposed to exploit their respective advantages. Firstly, the improved Dark Channel Prior algorithm is used to preprocess the visible haze image. Secondly, the improved SURF algorithm is used to register the infrared image and the haze-free visible image. Finally, the weighted fusion algorithm based on information complementary is used to fuse the image. Experiments show that the proposed method can improve the clarity of the visible target and highlight the occluded infrared target for target recognition.

  17. Integrated cryptosporidium assay to determine oocyst density, infectivity, and genotype for risk assessment of source and reuse water.

    King, Brendon; Fanok, Stella; Phillips, Renae; Swaffer, Brooke; Monis, Paul

    2015-05-15

    Cryptosporidium continues to be problematic for the water industry, with risk assessments often indicating that treatment barriers may fail under extreme conditions. However, risk analyses have historically used oocyst densities and not considered either oocyst infectivity or species/genotype, which can result in an overestimation of risk if the oocysts are not human infective. We describe an integrated assay for determining oocyst density, infectivity, and genotype from a single-sample concentrate, an important advance that overcomes the need for processing multiple-grab samples or splitting sample concentrates for separate analyses. The assay incorporates an oocyst recovery control and is compatible with standard primary concentration techniques. Oocysts were purified from primary concentrates using immunomagnetic separation prior to processing by an infectivity assay. Plate-based cell culture was used to detect infectious foci, with a monolayer washing protocol developed to allow recovery and enumeration of oocysts. A simple DNA extraction protocol was developed to allow typing of any wells containing infectious Cryptosporidium. Water samples from a variety of source water and wastewater matrices, including a semirural catchment, wastewater, an aquifer recharge site, and storm water, were analyzed using the assay. Results demonstrate that the assay can reliably determine oocyst densities, infectivity, and genotype from single-grab samples for a variety of water matrices and emphasize the varying nature of Cryptosporidium risk extant throughout source waters and wastewaters. This assay should therefore enable a more comprehensive understanding of Cryptosporidium risk for different water sources, assisting in the selection of appropriate risk mitigation measures. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  18. Axonal diameter and density estimated with 7-Tesla hybrid diffusion imaging in transgenic Alzheimer rats

    Daianu, Madelaine; Jacobs, Russell E.; Town, Terrence; Thompson, Paul M.

    2016-03-01

    Diffusion-weighted MR imaging (DWI) is a powerful tool to study brain tissue microstructure. DWI is sensitive to subtle changes in the white matter (WM), and can provide insight into abnormal brain changes in diseases such as Alzheimer's disease (AD). In this study, we used 7-Tesla hybrid diffusion imaging (HYDI) to scan 3 transgenic rats (line TgF344-AD; that model the full clinico-pathological spectrum of the human disease) ex vivo at 10, 15 and 24 months. We acquired 300 DWI volumes across 5 q-sampling shells (b=1000, 3000, 4000, 8000, 12000 s/mm2). From the top three b-value shells with highest signal-to-noise ratios, we reconstructed markers of WM disease, including indices of axon density and diameter in the corpus callosum (CC) - directly quantifying processes that occur in AD. As expected, apparent anisotropy progressively decreased with age; there were also decreases in the intra- and extra-axonal MR signal along axons. Axonal diameters were larger in segments of the CC (splenium and body, but not genu), possibly indicating neuritic dystrophy - characterized by enlarged axons and dendrites as previously observed at the ultrastructural level (see Cohen et al., J. Neurosci. 2013). This was further supported by increases in MR signals trapped in glial cells, CSF and possibly other small compartments in WM structures. Finally, tractography detected fewer fibers in the CC at 10 versus 24 months of age. These novel findings offer great potential to provide technical and scientific insight into the biology of brain disease.

  19. Electron cyclotron resonance ion source plasma characterization by X-ray spectroscopy and X-ray imaging

    Mascali, David, E-mail: davidmascali@lns.infn.it; Castro, Giuseppe; Celona, Luigi; Neri, Lorenzo; Gammino, Santo [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Biri, Sándor; Rácz, Richárd; Pálinkás, József [Institute for Nuclear Research (Atomki), Hungarian Academy of Sciences, Bem tér 18/c, H-4026 Debrecen (Hungary); Caliri, Claudia [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Università degli Studi di Catania, Dip.to di Fisica e Astronomia, via Santa Sofia 64, 95123 Catania (Italy); Romano, Francesco Paolo [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); CNR, Istituto per i Beni Archeologici e Monumentali, Via Biblioteca 4, 95124 Catania (Italy); Torrisi, Giuseppe [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Università Mediterranea di Reggio Calabria, DIIES, Via Graziella, I-89100 Reggio Calabria (Italy)

    2016-02-15

    An experimental campaign aiming to investigate electron cyclotron resonance (ECR) plasma X-ray emission has been recently carried out at the ECRISs—Electron Cyclotron Resonance Ion Sources laboratory of Atomki based on a collaboration between the Debrecen and Catania ECR teams. In a first series, the X-ray spectroscopy was performed through silicon drift detectors and high purity germanium detectors, characterizing the volumetric plasma emission. The on-purpose developed collimation system was suitable for direct plasma density evaluation, performed “on-line” during beam extraction and charge state distribution characterization. A campaign for correlating the plasma density and temperature with the output charge states and the beam intensity for different pumping wave frequencies, different magnetic field profiles, and single-gas/gas-mixing configurations was carried out. The results reveal a surprisingly very good agreement between warm-electron density fluctuations, output beam currents, and the calculated electromagnetic modal density of the plasma chamber. A charge-coupled device camera coupled to a small pin-hole allowing X-ray imaging was installed and numerous X-ray photos were taken in order to study the peculiarities of the ECRIS plasma structure.

  20. MANTA--an open-source, high density electrophysiology recording suite for MATLAB.

    Englitz, B; David, S V; Sorenson, M D; Shamma, S A

    2013-01-01

    The distributed nature of nervous systems makes it necessary to record from a large number of sites in order to decipher the neural code, whether single cell, local field potential (LFP), micro-electrocorticograms (μECoG), electroencephalographic (EEG), magnetoencephalographic (MEG) or in vitro micro-electrode array (MEA) data are considered. High channel-count recordings also optimize the yield of a preparation and the efficiency of time invested by the researcher. Currently, data acquisition (DAQ) systems with high channel counts (>100) can be purchased from a limited number of companies at considerable prices. These systems are typically closed-source and thus prohibit custom extensions or improvements by end users. We have developed MANTA, an open-source MATLAB-based DAQ system, as an alternative to existing options. MANTA combines high channel counts (up to 1440 channels/PC), usage of analog or digital headstages, low per channel cost (1 year, recording reliably from 128 channels. It offers a growing list of features, including integrated spike sorting, PSTH and CSD display and fully customizable electrode array geometry (including 3D arrays), some of which are not available in commercial systems. MANTA runs on a typical PC and communicates via TCP/IP and can thus be easily integrated with existing stimulus generation/control systems in a lab at a fraction of the cost of commercial systems. With modern neuroscience developing rapidly, MANTA provides a flexible platform that can be rapidly adapted to the needs of new analyses and questions. Being open-source, the development of MANTA can outpace commercial solutions in functionality, while maintaining a low price-point.

  1. MANTA – An Open-Source, High Density Electrophysiology Recording Suite for MATLAB

    Bernhard eEnglitz

    2013-05-01

    Full Text Available The distributed nature of nervous systems makes it necessary to record from a large number of sites in order to break the neural code, whether single cell, local field potential (LFP, micro-electrocorticograms (μECoG, electroencephalographic (EEG, magnetoencephalographic (MEG or in vitro micro-electrode array (MEA data are considered. High channel-count recordings also optimize the yield of a preparation and the efficiency of time invested by the researcher. Currently, data acquisition (DAQ systems with high channel counts (>100 can be purchased from a limited number of companies at considerable prices. These systems are typically closed-source and thus prohibit custom extensions or improvements by end users.We have developed MANTA, an open-source MATLAB-based DAQ system, as an alternative to existing options. MANTA combines high channel counts (up to 1440 channels/PC, usage of analog or digital headstages, low per channel cost (<$90/channel, feature-rich display & filtering, a user-friendly interface, and a modular design permitting easy addition of new features. MANTA is licensed under the GPL and free of charge. The system has been tested by daily use in multiple setups for >1 year, recording reliably from 128 channels. It offers a growing list of features, including integrated spike sorting, PSTH and CSD display and fully customizable electrode array geometry (including 3D arrays, some of which are not available in commercial systems. MANTA runs on a typical PC and communicates via TCP/IP and can thus be easily integrated with existing stimulus generation/control systems in a lab at a fraction of the cost of commercial systems.With modern neuroscience developing rapidly, MANTA provides a flexible platform that can be rapidly adapted to the needs of new analyses and questions. Being open-source, the development of MANTA can outpace commercial solutions in functionality, while maintaining a low price-point.

  2. A rotating modulation imager for locating mid-range point sources

    Kowash, B.R.; Wehe, D.K.; Fessler, J.A.

    2009-01-01

    Rotating modulation collimators (RMC) are relatively simple indirect imaging devices that have proven useful in gamma ray astronomy (far field) and have more recently been studied for medical imaging (very near field). At the University of Michigan a RMC has been built to study the performance for homeland security applications. This research highlights the imaging performance of this system and focuses on three distinct regions in the RMC field of view that can impact the search for hidden sources. These regions are a blind zone around the axis of rotation, a two mask image zone that extends from the blind zone to the edge of the field of view, and a single mask image zone that occurs when sources fall outside the field of view of both masks. By considering the extent and impact of these zones, the size of the two mask region can be optimized for the best system performance.

  3. Efficient image enhancement using sparse source separation in the Retinex theory

    Yoon, Jongsu; Choi, Jangwon; Choe, Yoonsik

    2017-11-01

    Color constancy is the feature of the human vision system (HVS) that ensures the relative constancy of the perceived color of objects under varying illumination conditions. The Retinex theory of machine vision systems is based on the HVS. Among Retinex algorithms, the physics-based algorithms are efficient; however, they generally do not satisfy the local characteristics of the original Retinex theory because they eliminate global illumination from their optimization. We apply the sparse source separation technique to the Retinex theory to present a physics-based algorithm that satisfies the locality characteristic of the original Retinex theory. Previous Retinex algorithms have limited use in image enhancement because the total variation Retinex results in an overly enhanced image and the sparse source separation Retinex cannot completely restore the original image. In contrast, our proposed method preserves the image edge and can very nearly replicate the original image without any special operation.

  4. An update on carbon nanotube-enabled X-ray sources for biomedical imaging.

    Puett, Connor; Inscoe, Christina; Hartman, Allison; Calliste, Jabari; Franceschi, Dora K; Lu, Jianping; Zhou, Otto; Lee, Yueh Z

    2018-01-01

    A new imaging technology has emerged that uses carbon nanotubes (CNT) as the electron emitter (cathode) for the X-ray tube. Since the performance of the CNT cathode is controlled by simple voltage manipulation, CNT-enabled X-ray sources are ideal for the repetitive imaging steps needed to capture three-dimensional information. As such, they have allowed the development of a gated micro-computed tomography (CT) scanner for small animal research as well as stationary tomosynthesis, an experimental technology for large field-of-view human imaging. The small animal CT can acquire images at specific points in the respiratory and cardiac cycles. Longitudinal imaging therefore becomes possible and has been applied to many research questions, ranging from tumor response to the noninvasive assessment of cardiac output. Digital tomosynthesis (DT) is a low-dose and low-cost human imaging tool that captures some depth information. Known as three-dimensional mammography, DT is now used clinically for breast imaging. However, the resolution of currently-approved DT is limited by the need to swing the X-ray source through space to collect a series of projection views. An array of fixed and distributed CNT-enabled sources provides the solution and has been used to construct stationary DT devices for breast, lung, and dental imaging. To date, over 100 patients have been imaged on Institutional Review Board-approved study protocols. Early experience is promising, showing an excellent conspicuity of soft-tissue features, while also highlighting technical and post-acquisition processing limitations that are guiding continued research and development. Additionally, CNT-enabled sources are being tested in miniature X-ray tubes that are capable of generating adequate photon energies and tube currents for clinical imaging. Although there are many potential applications for these small field-of-view devices, initial experience has been with an X-ray source that can be inserted into the

  5. Fiji: an open-source platform for biological-image analysis.

    Schindelin, Johannes; Arganda-Carreras, Ignacio; Frise, Erwin; Kaynig, Verena; Longair, Mark; Pietzsch, Tobias; Preibisch, Stephan; Rueden, Curtis; Saalfeld, Stephan; Schmid, Benjamin; Tinevez, Jean-Yves; White, Daniel James; Hartenstein, Volker; Eliceiri, Kevin; Tomancak, Pavel; Cardona, Albert

    2012-06-28

    Fiji is a distribution of the popular open-source software ImageJ focused on biological-image analysis. Fiji uses modern software engineering practices to combine powerful software libraries with a broad range of scripting languages to enable rapid prototyping of image-processing algorithms. Fiji facilitates the transformation of new algorithms into ImageJ plugins that can be shared with end users through an integrated update system. We propose Fiji as a platform for productive collaboration between computer science and biology research communities.

  6. Dose calibrations of itensifying screens and neutral density filters for use on pulsed x-ray sources

    Gersten, M.; Rauch, J.E.; Shannon, J.

    1983-01-01

    We calibrated three intensifying screens: Kodak Lanex Regular, Kodak X-Omatic Regular, and Kodak X-Omatic Fine, with relative speeds of 400, 100, and 15 for exposures to a 85 keV bremsstrahling spectrum when used in conjunction with Ortho G film. We also calibrated three neutral density filters: 0.6, 1, and 2 OD. When the screens are used in conjunction with the neutral density filters, 12 configurations can be obtained, with a total dynamic range of 2700. The film/screen/filter pack calibrations were performed in support of the bremsstrahlung experiments on Maxwell Laboratories BLACKJACK 5' pulse generator; the film/screen/filter packs are used to record pinhole photographs, one of the major diagnostics in the program. Because of reciprocity failure associated with the exposure of photographic film by visible light, an intense pulsed X-ray source was needed for the calibration. We used Maxwell Laboratories modular bremsstrahlung source, MBS. In the mode used (mean electron energy 213 + or - 6 keV, peak diode voltage 264 + or - 8 keV, and peak diode current 368 + or - 24 kA), a source strength of 47 + or - 2 J was obtained in a 30 + or - 1.2 ns FWHM pulse. In this mode, 41 + or - 4 percent of the fluence was above 67 keV. In this experiment, the machine operating parameters were held constant and the flux on the film/screen/filter pack was varied between 1.5 x 10 -3 - 5.6 x 10 -8 J/cm 2 . This was achieved by varying the distance between the film/screen/filter pack and the source and-by aperturing the source. The fil/screen/filter pack used for the calibration had three horizontal strips of screen pairs, overlayed with three vertical strips of neutral density filter pairs. One vertical section was left unfiltered. In this configuration 12 exposures are obtained simulatenously. The dose was measured with four TLD's placed inside the film/screen/filter pack at four corners

  7. Direct atomic imaging and density functional theory study of the Au24Pd1 cluster catalyst.

    Bruma, A; Negreiros, F R; Xie, S; Tsukuda, T; Johnston, R L; Fortunelli, A; Li, Z Y

    2013-10-21

    In this study we report a direct, atomic-resolution imaging of calcined Au24Pd1 clusters supported on multiwall carbon nanotubes by employing aberration-corrected scanning transmission electron microscopy. Using gold atoms as mass standards, we confirm the cluster size to be 25 ± 2, in agreement with the Au24Pd1(SR)18 precursor used in the synthesis. Concurrently, a Density-Functional/Basin-Hopping computational algorithm is employed to locate the low-energy configurations of free Au24Pd1 cluster. Cage structures surrounding a single core atom are found to be favored, with a slight preference for Pd to occupy the core site. The cluster shows a tendency toward elongated arrangements, consistent with experimental data. The degree of electron transfer from the Pd dopant to Au is quantified through a Löwdin charge analysis, suggesting that Pd may act as an electron promoter to the surrounding Au atoms when they are involved in catalytic reactions.

  8. Detection of pulmonary nodules at paediatric CT: maximum intensity projections and axial source images are complementary

    Kilburn-Toppin, Fleur; Arthurs, Owen J.; Tasker, Angela D.; Set, Patricia A.K.

    2013-01-01

    Maximum intensity projection (MIP) images might be useful in helping to differentiate small pulmonary nodules from adjacent vessels on thoracic multidetector CT (MDCT). The aim was to evaluate the benefits of axial MIP images over axial source images for the paediatric chest in an interobserver variability study. We included 46 children with extra-pulmonary solid organ malignancy who had undergone thoracic MDCT. Three radiologists independently read 2-mm axial and 10-mm MIP image datasets, recording the number of nodules, size and location, overall time taken and confidence. There were 83 nodules (249 total reads among three readers) in 46 children (mean age 10.4 ± 4.98 years, range 0.3-15.9 years; 24 boys). Consensus read was used as the reference standard. Overall, three readers recorded significantly more nodules on MIP images (228 vs. 174; P < 0.05), improving sensitivity from 67% to 77.5% (P < 0.05) but with lower positive predictive value (96% vs. 85%, P < 0.005). MIP images took significantly less time to read (71.6 ± 43.7 s vs. 92.9 ± 48.7 s; P < 0.005) but did not improve confidence levels. Using 10-mm axial MIP images for nodule detection in the paediatric chest enhances diagnostic performance, improving sensitivity and reducing reading time when compared with conventional axial thin-slice images. Axial MIP and axial source images are complementary in thoracic nodule detection. (orig.)

  9. Screen-detected versus interval cancers: Effect of imaging modality and breast density in the Flemish Breast Cancer Screening Programme

    Timmermans, Lore; Bacher, Klaus; Thierens, Hubert [Ghent University, Department of Basic Medical Sciences, QCC-Gent, Ghent (Belgium); Bleyen, Luc; Herck, Koen van [Ghent University, Centrum voor Preventie en Vroegtijdige Opsporing van Kanker, Ghent (Belgium); Lemmens, Kim; Ongeval, Chantal van; Steen, Andre van [University Hospitals Leuven, Department of Radiology, Leuven (Belgium); Martens, Patrick [Centrum voor Kankeropsporing, Bruges (Belgium); Brabander, Isabel de [Belgian Cancer Registry, Brussels (Belgium); Goossens, Mathieu [UZ Brussel, Dienst Kankerpreventie, Brussels (Belgium)

    2017-09-15

    To investigate if direct radiography (DR) performs better than screen-film mammography (SF) and computed radiography (CR) in dense breasts in a decentralized organised Breast Cancer Screening Programme. To this end, screen-detected versus interval cancers were studied in different BI-RADS density classes for these imaging modalities. The study cohort consisted of 351,532 women who participated in the Flemish Breast Cancer Screening Programme in 2009 and 2010. Information on screen-detected and interval cancers, breast density scores of radiologist second readers, and imaging modality was obtained by linkage of the databases of the Centre of Cancer Detection and the Belgian Cancer Registry. Overall, 67% of occurring breast cancers are screen detected and 33% are interval cancers, with DR performing better than SF and CR. The interval cancer rate increases gradually with breast density, regardless of modality. In the high-density class, the interval cancer rate exceeds the cancer detection rate for SF and CR, but not for DR. DR is superior to SF and CR with respect to cancer detection rates for high-density breasts. To reduce the high interval cancer rate in dense breasts, use of an additional imaging technique in screening can be taken into consideration. (orig.)

  10. Screen-detected versus interval cancers: Effect of imaging modality and breast density in the Flemish Breast Cancer Screening Programme

    Timmermans, Lore; Bacher, Klaus; Thierens, Hubert; Bleyen, Luc; Herck, Koen van; Lemmens, Kim; Ongeval, Chantal van; Steen, Andre van; Martens, Patrick; Brabander, Isabel de; Goossens, Mathieu

    2017-01-01

    To investigate if direct radiography (DR) performs better than screen-film mammography (SF) and computed radiography (CR) in dense breasts in a decentralized organised Breast Cancer Screening Programme. To this end, screen-detected versus interval cancers were studied in different BI-RADS density classes for these imaging modalities. The study cohort consisted of 351,532 women who participated in the Flemish Breast Cancer Screening Programme in 2009 and 2010. Information on screen-detected and interval cancers, breast density scores of radiologist second readers, and imaging modality was obtained by linkage of the databases of the Centre of Cancer Detection and the Belgian Cancer Registry. Overall, 67% of occurring breast cancers are screen detected and 33% are interval cancers, with DR performing better than SF and CR. The interval cancer rate increases gradually with breast density, regardless of modality. In the high-density class, the interval cancer rate exceeds the cancer detection rate for SF and CR, but not for DR. DR is superior to SF and CR with respect to cancer detection rates for high-density breasts. To reduce the high interval cancer rate in dense breasts, use of an additional imaging technique in screening can be taken into consideration. (orig.)

  11. The complex fate in plasma of gadolinium incorporated into high-density lipoproteins used for magnetic imaging of atherosclerotic plaques

    Barazza, Alessandra; Blachford, Courtney; Even-Or, Orli; Joaquin, Victor A.; Briley-Saebo, Karen C.; Chen, Wei; Jiang, Xian-Cheng; Mulder, Willem J. M.; Cormode, David P.; Fayad, Zahi A.; Fisher, Edward A.

    2013-01-01

    We have previously reported enhancing the imaging of atherosclerotic plaques in mice using reconstituted high density lipoproteins (HDL) as nanocarriers for the MRI contrast agent gadolinium (Gd). This study focuses on the underlying mechanisms of Gd delivery to atherosclerotic plaques. HDL, LDL,

  12. Time Reversal Migration for Passive Sources Using a Maximum Variance Imaging Condition

    Wang, H.; Alkhalifah, Tariq Ali

    2017-01-01

    The conventional time-reversal imaging approach for micro-seismic or passive source location is based on focusing the back-propagated wavefields from each recorded trace in a source image. It suffers from strong background noise and limited acquisition aperture, which may create unexpected artifacts and cause error in the source location. To overcome such a problem, we propose a new imaging condition for microseismic imaging, which is based on comparing the amplitude variance in certain windows, and use it to suppress the artifacts as well as find the right location for passive sources. Instead of simply searching for the maximum energy point in the back-propagated wavefield, we calculate the amplitude variances over a window moving in both space and time axis to create a highly resolved passive event image. The variance operation has negligible cost compared with the forward/backward modeling operations, which reveals that the maximum variance imaging condition is efficient and effective. We test our approach numerically on a simple three-layer model and on a piece of the Marmousi model as well, both of which have shown reasonably good results.

  13. Time Reversal Migration for Passive Sources Using a Maximum Variance Imaging Condition

    Wang, H.

    2017-05-26

    The conventional time-reversal imaging approach for micro-seismic or passive source location is based on focusing the back-propagated wavefields from each recorded trace in a source image. It suffers from strong background noise and limited acquisition aperture, which may create unexpected artifacts and cause error in the source location. To overcome such a problem, we propose a new imaging condition for microseismic imaging, which is based on comparing the amplitude variance in certain windows, and use it to suppress the artifacts as well as find the right location for passive sources. Instead of simply searching for the maximum energy point in the back-propagated wavefield, we calculate the amplitude variances over a window moving in both space and time axis to create a highly resolved passive event image. The variance operation has negligible cost compared with the forward/backward modeling operations, which reveals that the maximum variance imaging condition is efficient and effective. We test our approach numerically on a simple three-layer model and on a piece of the Marmousi model as well, both of which have shown reasonably good results.

  14. A pseudo-discrete algebraic reconstruction technique (PDART) prior image-based suppression of high density artifacts in computed tomography

    Pua, Rizza; Park, Miran; Wi, Sunhee; Cho, Seungryong, E-mail: scho@kaist.ac.kr

    2016-12-21

    We propose a hybrid metal artifact reduction (MAR) approach for computed tomography (CT) that is computationally more efficient than a fully iterative reconstruction method, but at the same time achieves superior image quality to the interpolation-based in-painting techniques. Our proposed MAR method, an image-based artifact subtraction approach, utilizes an intermediate prior image reconstructed via PDART to recover the background information underlying the high density objects. For comparison, prior images generated by total-variation minimization (TVM) algorithm, as a realization of fully iterative approach, were also utilized as intermediate images. From the simulation and real experimental results, it has been shown that PDART drastically accelerates the reconstruction to an acceptable quality of prior images. Incorporating PDART-reconstructed prior images in the proposed MAR scheme achieved higher quality images than those by a conventional in-painting method. Furthermore, the results were comparable to the fully iterative MAR that uses high-quality TVM prior images. - Highlights: • An accelerated reconstruction method, PDART, is proposed for exterior problems. • With a few iterations, soft prior image was reconstructed from the exterior data. • PDART framework has enabled an efficient hybrid metal artifact reduction in CT.

  15. IQM: an extensible and portable open source application for image and signal analysis in Java.

    Kainz, Philipp; Mayrhofer-Reinhartshuber, Michael; Ahammer, Helmut

    2015-01-01

    Image and signal analysis applications are substantial in scientific research. Both open source and commercial packages provide a wide range of functions for image and signal analysis, which are sometimes supported very well by the communities in the corresponding fields. Commercial software packages have the major drawback of being expensive and having undisclosed source code, which hampers extending the functionality if there is no plugin interface or similar option available. However, both variants cannot cover all possible use cases and sometimes custom developments are unavoidable, requiring open source applications. In this paper we describe IQM, a completely free, portable and open source (GNU GPLv3) image and signal analysis application written in pure Java. IQM does not depend on any natively installed libraries and is therefore runnable out-of-the-box. Currently, a continuously growing repertoire of 50 image and 16 signal analysis algorithms is provided. The modular functional architecture based on the three-tier model is described along the most important functionality. Extensibility is achieved using operator plugins, and the development of more complex workflows is provided by a Groovy script interface to the JVM. We demonstrate IQM's image and signal processing capabilities in a proof-of-principle analysis and provide example implementations to illustrate the plugin framework and the scripting interface. IQM integrates with the popular ImageJ image processing software and is aiming at complementing functionality rather than competing with existing open source software. Machine learning can be integrated into more complex algorithms via the WEKA software package as well, enabling the development of transparent and robust methods for image and signal analysis.

  16. Performance of water source heat pump system using high-density polyethylene tube heat exchanger wound with square copper wire

    Xin Wen Zhang

    2015-07-01

    Full Text Available Surface water source heat pump system is an energy-efficient heat pump system. Surface water heat exchanger is an important part of heat pump system that can affect the performance of the system. In order to enhance the performance of the system, the overall heat transfer coefficient (U value of the water exchanger using a 32A square copper coiled high-density polyethylene tube was researched. Comparative experiments were conducted between the performance of the coiled high-density polyethylene tube and the 32A smooth high-density polyethylene tube. At the same time, the coefficient of performance of the heat pump was investigated. According to the result, the U value of the coiled tube was 18% higher than that of the smooth tube in natural convection and 19% higher in forced convection. The coefficient of performance of the heat pump with the coiled tube is higher than that with the smooth tube. The economic evaluation of the coiled tube was also investigated.

  17. Blind source separation of ex-vivo aorta tissue multispectral images.

    Galeano, July; Perez, Sandra; Montoya, Yonatan; Botina, Deivid; Garzón, Johnson

    2015-05-01

    Blind Source Separation methods (BSS) aim for the decomposition of a given signal in its main components or source signals. Those techniques have been widely used in the literature for the analysis of biomedical images, in order to extract the main components of an organ or tissue under study. The analysis of skin images for the extraction of melanin and hemoglobin is an example of the use of BSS. This paper presents a proof of concept of the use of source separation of ex-vivo aorta tissue multispectral Images. The images are acquired with an interference filter-based imaging system. The images are processed by means of two algorithms: Independent Components analysis and Non-negative Matrix Factorization. In both cases, it is possible to obtain maps that quantify the concentration of the main chromophores present in aortic tissue. Also, the algorithms allow for spectral absorbance of the main tissue components. Those spectral signatures were compared against the theoretical ones by using correlation coefficients. Those coefficients report values close to 0.9, which is a good estimator of the method's performance. Also, correlation coefficients lead to the identification of the concentration maps according to the evaluated chromophore. The results suggest that Multi/hyper-spectral systems together with image processing techniques is a potential tool for the analysis of cardiovascular tissue.

  18. Source segregation and food waste prevention activities in high-density households in a deprived urban area

    Rispo, A.; Williams, I.D.; Shaw, P.J.

    2015-01-01

    Highlights: • Study of waste management in economically and socially deprived high-density housing. • Food waste segregation, prevention and recycling activities investigated. • Study involved a waste audit and household survey of 1034 households. • Populations in such areas are “hard-to-reach”. • Exceptional efforts and additional resources are required to improve performance. - Abstract: A waste audit and a household questionnaire survey were conducted in high-density housing estates in one of the most economically and socially deprived areas of England (Haringey, London). Such areas are under-represented in published research. The study examined source segregation, potential participation in a food waste segregation scheme, and food waste prevention activities in five estates (1034 households). The results showed that: contamination of recyclables containers was low; ca. 28% of the mixed residual waste’s weight was recyclable; food waste comprised a small proportion of the waste from these residents, probably because of their relatively disadvantaged economic circumstances; and the recycling profile reflected an intermittent pattern of behaviour. Although the majority of respondents reported that they would participate in a food waste separation scheme, the response rate was low and many responses of “don’t know” were recorded. Municipalities committed to foster improved diversion from landfill need to recognise that there is no “quick and easy fix”, regardless of local or national aspirations. Lasting and sustained behaviour change requires time and the quality of service provision and associated infrastructure play a fundamental role in facilitating residents to participate effectively in waste management activities that maximise capture of source-segregated materials. Populations in deprived areas that reside in high-rise, high-density dwellings are “hard-to-reach” in terms of participation in recycling schemes and exceptional

  19. Source segregation and food waste prevention activities in high-density households in a deprived urban area

    Rispo, A.; Williams, I.D., E-mail: idw@soton.ac.uk; Shaw, P.J.

    2015-10-15

    Highlights: • Study of waste management in economically and socially deprived high-density housing. • Food waste segregation, prevention and recycling activities investigated. • Study involved a waste audit and household survey of 1034 households. • Populations in such areas are “hard-to-reach”. • Exceptional efforts and additional resources are required to improve performance. - Abstract: A waste audit and a household questionnaire survey were conducted in high-density housing estates in one of the most economically and socially deprived areas of England (Haringey, London). Such areas are under-represented in published research. The study examined source segregation, potential participation in a food waste segregation scheme, and food waste prevention activities in five estates (1034 households). The results showed that: contamination of recyclables containers was low; ca. 28% of the mixed residual waste’s weight was recyclable; food waste comprised a small proportion of the waste from these residents, probably because of their relatively disadvantaged economic circumstances; and the recycling profile reflected an intermittent pattern of behaviour. Although the majority of respondents reported that they would participate in a food waste separation scheme, the response rate was low and many responses of “don’t know” were recorded. Municipalities committed to foster improved diversion from landfill need to recognise that there is no “quick and easy fix”, regardless of local or national aspirations. Lasting and sustained behaviour change requires time and the quality of service provision and associated infrastructure play a fundamental role in facilitating residents to participate effectively in waste management activities that maximise capture of source-segregated materials. Populations in deprived areas that reside in high-rise, high-density dwellings are “hard-to-reach” in terms of participation in recycling schemes and exceptional

  20. Line x-ray source for diffraction enhanced imaging in clinical and industrial applications

    Wang, Xiaoqin

    Mammography is one type of imaging modalities that uses a low-dose x-ray or other radiation sources for examination of breasts. It plays a central role in early detection of breast cancers. The material similarity of tumor-cell and health cell, breast implants surgery and other factors, make the breast cancers hard to visualize and detect. Diffraction enhanced imaging (DEI), first proposed and investigated by D. Chapman is a new x-ray radiographic imaging modality using monochromatic x-rays from a synchrotron source, which produced images of thick absorbing objects that are almost completely free of scatter. It shows dramatically improved contrast over standard imaging when applied to the same phantom. The contrast is based not only on attenuation but also on the refraction and diffraction properties of the sample. This imaging method may improve image quality of mammography, other medical applications, industrial radiography for non-destructive testing and x-ray computed tomography. However, the size, and cost, of a synchrotron source limits the application of the new modality to be applicable at clinical levels. This research investigates the feasibility of a designed line x-ray source to produce intensity compatible to synchrotron sources. It is composed of a 2-cm in length tungsten filament, installed on a carbon steel filament cup (backing plate), as the cathode and a stationary oxygen-free copper anode with molybdenum coating on the front surface serves as the target. Characteristic properties of the line x-ray source were computationally studied and the prototype was experimentally investigated. SIMIION code was used to computationally study the electron trajectories emanating from the filament towards the molybdenum target. A Faraday cup on the prototype device, proof-of-principle, was used to measure the distribution of electrons on the target, which compares favorably to computational results. The intensities of characteristic x-ray for molybdenum

  1. Development of CD3 cell quantitation algorithms for renal allograft biopsy rejection assessment utilizing open source image analysis software.

    Moon, Andres; Smith, Geoffrey H; Kong, Jun; Rogers, Thomas E; Ellis, Carla L; Farris, Alton B Brad

    2018-02-01

    Renal allograft rejection diagnosis depends on assessment of parameters such as interstitial inflammation; however, studies have shown interobserver variability regarding interstitial inflammation assessment. Since automated image analysis quantitation can be reproducible, we devised customized analysis methods for CD3+ T-cell staining density as a measure of rejection severity and compared them with established commercial methods along with visual assessment. Renal biopsy CD3 immunohistochemistry slides (n = 45), including renal allografts with various degrees of acute cellular rejection (ACR) were scanned for whole slide images (WSIs). Inflammation was quantitated in the WSIs using pathologist visual assessment, commercial algorithms (Aperio nuclear algorithm for CD3+ cells/mm 2 and Aperio positive pixel count algorithm), and customized open source algorithms developed in ImageJ with thresholding/positive pixel counting (custom CD3+%) and identification of pixels fulfilling "maxima" criteria for CD3 expression (custom CD3+ cells/mm 2 ). Based on visual inspections of "markup" images, CD3 quantitation algorithms produced adequate accuracy. Additionally, CD3 quantitation algorithms correlated between each other and also with visual assessment in a statistically significant manner (r = 0.44 to 0.94, p = 0.003 to algorithms presents salient correlations with established methods of CD3 quantitation. These analysis techniques are promising and highly customizable, providing a form of on-slide "flow cytometry" that can facilitate additional diagnostic accuracy in tissue-based assessments.

  2. Topographic anatomy of paraclinoid carotid artery aneurysms: usefulness of MR angiographic source images

    Nagasawa, S.; Deguchi, J.; Arai, M.; Tanaka, H.; Kawanishi, M.; Ohta, T.

    1997-01-01

    We evaluated the usefulness of magnetic resonance angiography (MRA) for showing the topography of paraclinoid carotid artery aneurysms in 27 patients with 30 paraclinoid aneurysms undergoing conventional angiography, three-dimensional time-of-flight MRA and surgery. The anatomy shown on the axial MRA source images was consistent with that found at surgery. The neck of the aneurysm could always be identified on the source images, while it could not be analysed exactly on conventional angiography in 3 cases (10 %). The optic nerves, including those displaced by the aneurysm, were recognised in all patients. The anterior clinoid process was shown as a low-intensity rim or area contiguous with the cortical bone. The source images were of great value in understanding the topography of paraclinoid carotid artery aneurysms. (orig.). With 2 figs

  3. Phase contrast imaging using a micro focus x-ray source

    Zhou, Wei; Majidi, Keivan; Brankov, Jovan G.

    2014-09-01

    Phase contrast x-ray imaging, a new technique to increase the imaging contrast for the tissues with close attenuation coefficients, has been studied since mid 1990s. This technique reveals the possibility to show the clear details of the soft tissues and tumors in small scale resolution. A compact and low cost phase contrast imaging system using a conventional x-ray source is described in this paper. Using the conventional x-ray source is of great importance, because it provides the possibility to use the method in hospitals and clinical offices. Simple materials and components are used in the setup to keep the cost in a reasonable and affordable range.Tungsten Kα1 line with the photon energy 59.3 keV was used for imaging. Some of the system design details are discussed. The method that was used to stabilize the system is introduced. A chicken thigh bone tissue sample was used for imaging followed by the image quality, image acquisition time and the potential clinical application discussion. High energy x-ray beam can be used in phase contrast imaging. Therefore the radiation dose to the patients can be greatly decreased compared to the traditional x-ray radiography.

  4. A density-based segmentation for 3D images, an application for X-ray micro-tomography

    Tran, Thanh N.; Nguyen, Thanh T.; Willemsz, Tofan A.; Kessel, Gijs van; Frijlink, Henderik W.; Voort Maarschalk, Kees van der

    2012-01-01

    Highlights: ► We revised the DBSCAN algorithm for segmentation and clustering of large 3D image dataset and classified multivariate image. ► The algorithm takes into account the coordinate system of the image data to improve the computational performance. ► The algorithm solved the instability problem in boundaries detection of the original DBSCAN. ► The segmentation results were successfully validated with synthetic 3D image and 3D XMT image of a pharmaceutical powder. - Abstract: Density-based spatial clustering of applications with noise (DBSCAN) is an unsupervised classification algorithm which has been widely used in many areas with its simplicity and its ability to deal with hidden clusters of different sizes and shapes and with noise. However, the computational issue of the distance table and the non-stability in detecting the boundaries of adjacent clusters limit the application of the original algorithm to large datasets such as images. In this paper, the DBSCAN algorithm was revised and improved for image clustering and segmentation. The proposed clustering algorithm presents two major advantages over the original one. Firstly, the revised DBSCAN algorithm made it applicable for large 3D image dataset (often with millions of pixels) by using the coordinate system of the image data. Secondly, the revised algorithm solved the non-stability issue of boundary detection in the original DBSCAN. For broader applications, the image dataset can be ordinary 3D images or in general, it can also be a classification result of other type of image data e.g. a multivariate image.

  5. 2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements.

    Lin, L; Ding, W X; Brower, D L

    2014-11-01

    Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved.

  6. 2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements

    Lin, L.; Ding, W. X.; Brower, D. L.

    2014-01-01

    Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved

  7. Imaging x-ray sources at a finite distance in coded-mask instruments

    Donnarumma, Immacolata; Pacciani, Luigi; Lapshov, Igor; Evangelista, Yuri

    2008-01-01

    We present a method for the correction of beam divergence in finite distance sources imaging through coded-mask instruments. We discuss the defocusing artifacts induced by the finite distance showing two different approaches to remove such spurious effects. We applied our method to one-dimensional (1D) coded-mask systems, although it is also applicable in two-dimensional systems. We provide a detailed mathematical description of the adopted method and of the systematics introduced in the reconstructed image (e.g., the fraction of source flux collected in the reconstructed peak counts). The accuracy of this method was tested by simulating pointlike and extended sources at a finite distance with the instrumental setup of the SuperAGILE experiment, the 1D coded-mask x-ray imager onboard the AGILE (Astro-rivelatore Gamma a Immagini Leggero) mission. We obtained reconstructed images of good quality and high source location accuracy. Finally we show the results obtained by applying this method to real data collected during the calibration campaign of SuperAGILE. Our method was demonstrated to be a powerful tool to investigate the imaging response of the experiment, particularly the absorption due to the materials intercepting the line of sight of the instrument and the conversion between detector pixel and sky direction

  8. The Swift/UVOT catalogue of NGC 4321 star-forming sources: a case against density wave theory

    Ferreras, Ignacio; Cropper, Mark; Kawata, Daisuke; Page, Mat; Hoversten, Erik A.

    2012-08-01

    We study the star-forming regions in the spiral galaxy NGC 4321 (M100). We take advantage of the spatial resolution (2.5 arcsec full width at half-maximum) of the Swift/Ultraviolet/Optical Telescope camera and the availability of three ultraviolet (UV) passbands in the region 1600 spiral arms. The Hα luminosities of the sources have a strong decreasing radial trend, suggesting more massive star-forming regions in the central part of the galaxy. When segregated with respect to near-UV (NUV)-optical colour, blue sources have a significant excess of flux in the IR at 8 μm, revealing the contribution from polycyclic aromatic hydrocarbons, although the overall reddening of these sources stays below E(B - V) = 0.2 mag. The distribution of distances to the spiral arms is compared for subsamples selected according to Hα luminosity, NUV-optical colour or ages derived from a population synthesis model. An offset would be expected between these subsamples as a function of radius if the pattern speed of the spiral arm were constant - as predicted by classic density wave theory. No significant offsets are found, favouring instead a mechanism where the pattern speed has a radial dependence.

  9. Generator localization by current source density (CSD): Implications of volume conduction and field closure at intracranial and scalp resolutions

    Tenke, Craig E.; Kayser, Jürgen

    2012-01-01

    The topographic ambiguity and reference-dependency that has plagued EEG/ERP research throughout its history are largely attributable to volume conduction, which may be concisely described by a vector form of Ohm’s Law. This biophysical relationship is common to popular algorithms that infer neuronal generators via inverse solutions. It may be further simplified as Poisson’s source equation, which identifies underlying current generators from estimates of the second spatial derivative of the field potential (Laplacian transformation). Intracranial current source density (CSD) studies have dissected the “cortical dipole” into intracortical sources and sinks, corresponding to physiologically-meaningful patterns of neuronal activity at a sublaminar resolution, much of which is locally cancelled (i.e., closed field). By virtue of the macroscopic scale of the scalp-recorded EEG, a surface Laplacian reflects the radial projections of these underlying currents, representing a unique, unambiguous measure of neuronal activity at scalp. Although the surface Laplacian requires minimal assumptions compared to complex, model-sensitive inverses, the resulting waveform topographies faithfully summarize and simplify essential constraints that must be placed on putative generators of a scalp potential topography, even if they arise from deep or partially-closed fields. CSD methods thereby provide a global empirical and biophysical context for generator localization, spanning scales from intracortical to scalp recordings. PMID:22796039

  10. Rapid development of medical imaging tools with open-source libraries.

    Caban, Jesus J; Joshi, Alark; Nagy, Paul

    2007-11-01

    Rapid prototyping is an important element in researching new imaging analysis techniques and developing custom medical applications. In the last ten years, the open source community and the number of open source libraries and freely available frameworks for biomedical research have grown significantly. What they offer are now considered standards in medical image analysis, computer-aided diagnosis, and medical visualization. A cursory review of the peer-reviewed literature in imaging informatics (indeed, in almost any information technology-dependent scientific discipline) indicates the current reliance on open source libraries to accelerate development and validation of processes and techniques. In this survey paper, we review and compare a few of the most successful open source libraries and frameworks for medical application development. Our dual intentions are to provide evidence that these approaches already constitute a vital and essential part of medical image analysis, diagnosis, and visualization and to motivate the reader to use open source libraries and software for rapid prototyping of medical applications and tools.

  11. Curved crystal x-ray optics for monochromatic imaging with a clinical source.

    Bingölbali, Ayhan; MacDonald, C A

    2009-04-01

    Monochromatic x-ray imaging has been shown to increase contrast and reduce dose relative to conventional broadband imaging. However, clinical sources with very narrow energy bandwidth tend to have limited intensity and field of view. In this study, focused fan beam monochromatic radiation was obtained using doubly curved monochromator crystals. While these optics have been in use for microanalysis at synchrotron facilities for some time, this work is the first investigation of the potential application of curved crystal optics to clinical sources for medical imaging. The optics could be used with a variety of clinical sources for monochromatic slot scan imaging. The intensity was assessed and the resolution of the focused beam was measured using a knife-edge technique. A simulation model was developed and comparisons to the measured resolution were performed to verify the accuracy of the simulation to predict resolution for different conventional sources. A simple geometrical calculation was also developed. The measured, simulated, and calculated resolutions agreed well. Adequate resolution and intensity for mammography were predicted for appropriate source/optic combinations.

  12. Scanning Hall-probe microscopy system for two-dimensional imaging of critical current density in RE-123 coated conductors

    Higashikawa, K.; Inoue, M.; Kawaguchi, T.; Shiohara, K.; Imamura, K.; Kiss, T.; Iijima, Y.; Kakimoto, K.; Saitoh, T.; Izumi, T.

    2011-01-01

    Nondestructive characterization method of in-plane distribution of critical current density for coated conductors. Current distribution in a coated conductor compared with that from theoretical analysis. Relationship between local critical current density and local magnetic field. We have developed a characterization method for two-dimensional imaging of critical current density in coated conductors (CCs) based on scanning Hall-probe microscopy (SHPM). The distributions of the magnetic field around a sample were measured for several different conditions of external magnetic fields, and then were converted to those of the sheet current density which flowed to shield the external magnetic field or to trap the penetrated magnetic field. As a result, it was found that the amplitude of the sheet current density corresponded to that of critical current density almost in all the area of the sample except for the region where current direction changed. This indicates that we could obtain an in-plane distribution of the critical current density with a spatial resolution of around 100 μm in non-destructive manner by this method. We believe that this measurement will be a multifunctional and comprehensive characterization method for coated conductors.

  13. Density Imaging of Puy de Dôme Volcano by Joint Inversion of Muographic and Gravimetric Data

    Barnoud, A.; Niess, V.; Le Ménédeu, E.; Cayol, V.; Carloganu, C.

    2016-12-01

    We aim at jointly inverting high density muographic and gravimetric data to robustly infer the density structure of volcanoes. We use the puy de Dôme volcano in France as a proof of principle since high quality data sets are available for both muography and gravimetry. Gravimetric inversion and muography are independent methods that provide an estimation of density distributions. On the one hand, gravimetry allows to reconstruct 3D density variations by inversion. This process is well known to be ill-posed and intrinsically non unique, thus it requires additional constraints (eg. a priori density model). On the other hand, muography provides a direct measurement of 2D mean densities (radiographic images) from the detection of high energy atmospheric muons crossing the volcanic edifice. 3D density distributions can be computed from several radiographic images, but the number of images is generally limited by field constraints and by the limited number of available telescopes. Thus, muon tomography is also ill-posed in practice.In the case of the puy de Dôme volcano, the density structures inferred from gravimetric data (Portal et al. 2016) and from muographic data (Le Ménédeu et al. 2016) show a qualitative agreement but cannot be compared quantitatively. Because each method has different intrinsic resolutions due to the physics (Jourde et al., 2015), the joint inversion is expected to improve the robustness of the inversion. Such joint inversion has already been applied in a volcanic context (Nishiyama et al., 2013).Volcano muography requires state-of-art, high-resolution and large-scale muon detectors (Ambrosino et al., 2015). Instrumental uncertainties and systematic errors may constitute an important limitation for muography and should not be overlooked. For instance, low-energy muons are detected together with ballistic high-energy muons, decreasing the measured value of the mean density closed to the topography.Here, we jointly invert the gravimetric and

  14. Subgingival calculus imaging based on swept-source optical coherence tomography

    Hsieh, Yao-Sheng; Ho, Yi-Ching; Lee, Shyh-Yuan; Lu, Chih-Wei; Jiang, Cho-Pei; Chuang, Ching-Cheng; Wang, Chun-Yang; Sun, Chia-Wei

    2011-07-01

    We characterized and imaged dental calculus using swept-source optical coherence tomography (SS-OCT). The refractive indices of enamel, dentin, cementum, and calculus were measured as 1.625 +/- 0.024, 1.534 +/- 0.029, 1.570 +/- 0.021, and 2.097 +/- 0.094, respectively. Dental calculus leads strong scattering properties, and thus, the region can be identified from enamel with SS-OCT imaging. An extracted human tooth with calculus is covered with gingiva tissue as an in vitro sample for tomographic imaging.

  15. Rapid calibrated high-resolution hyperspectral imaging using tunable laser source

    Nguyen, Lam K.; Margalith, Eli

    2009-05-01

    We present a novel hyperspectral imaging technique based on tunable laser technology. By replacing the broadband source and tunable filters of a typical NIR imaging instrument, several advantages are realized, including: high spectral resolution, highly variable field-of-views, fast scan-rates, high signal-to-noise ratio, and the ability to use optical fiber for efficient and flexible sample illumination. With this technique, high-resolution, calibrated hyperspectral images over the NIR range can be acquired in seconds. The performance of system features will be demonstrated on two example applications: detecting melamine contamination in wheat gluten and separating bovine protein from wheat protein in cattle feed.

  16. Evaluation of imaging reformation with cone beam computed tomography for the assessment of bone density and shape in mandible

    Hong, Sang Woo; Kim, Gyu Tae; Choi, Yong Suk; Hwan, Eui Hwan

    2008-01-01

    Diagnostic estimation of destruction and formation of bone has the typical limit according to capacity of x-ray generator and image detector. So the aim of this study was to find out how much it can reproduce the shape and the density of bone in the case of using recently developed dental type of cone beam computed tomography, and which image is applied by new detector and mathematic calculation. Cone beam computed tomography (PSR 9000N, Asahi Roentgen Ind. Co., Ltd., Japan) and soft x-ray radiography were executed on dry mandible that was already decalcified during 5 hours, 10 hours, 15 hours, 20 hours, and 25 hours. Estimating and comparing of those came to the following results. The change of inferior border of mandible and anterior border of ramous in the region of cortical bone was observed between first 5 and 10 hours of decalcification. The reproduction of shape and density in the region of cortical bone and cancellous bone can be hardly observed at cone beam computed tomography compared with soft x-ray radiography. The difference of decrease of bone density according to hours of decalcification increase was not reproduced at cone beam computed tomography compared with soft x-ray radiography. CBCT images revealed higher spatial resolution. However, contrast resolution in region of low contrast sensitivity is the inferiority of images' property.

  17. Factors affecting the repeatability of gamma camera calibration for quantitative imaging applications using a sealed source

    Anizan, N; Wahl, R L; Frey, E C; Wang, H; Zhou, X C

    2015-01-01

    Several applications in nuclear medicine require absolute activity quantification of single photon emission computed tomography images. Obtaining a repeatable calibration factor that converts voxel values to activity units is essential for these applications. Because source preparation and measurement of the source activity using a radionuclide activity meter are potential sources of variability, this work investigated instrumentation and acquisition factors affecting repeatability using planar acquisition of sealed sources. The calibration factor was calculated for different acquisition and geometry conditions to evaluate the effect of the source size, lateral position of the source in the camera field-of-view (FOV), source-to-camera distance (SCD), and variability over time using sealed Ba-133 sources. A small region of interest (ROI) based on the source dimensions and collimator resolution was investigated to decrease the background effect. A statistical analysis with a mixed-effects model was used to evaluate quantitatively the effect of each variable on the global calibration factor variability. A variation of 1 cm in the measurement of the SCD from the assumed distance of 17 cm led to a variation of 1–2% in the calibration factor measurement using a small disc source (0.4 cm diameter) and less than 1% with a larger rod source (2.9 cm diameter). The lateral position of the source in the FOV and the variability over time had small impacts on calibration factor variability. The residual error component was well estimated by Poisson noise. Repeatability of better than 1% in a calibration factor measurement using a planar acquisition of a sealed source can be reasonably achieved. The best reproducibility was obtained with the largest source with a count rate much higher than the average background in the ROI, and when the SCD was positioned within 5 mm of the desired position. In this case, calibration source variability was limited by the quantum

  18. Free and open-source software application for the evaluation of coronary computed tomography angiography images.

    Hadlich, Marcelo Souza; Oliveira, Gláucia Maria Moraes; Feijóo, Raúl A; Azevedo, Clerio F; Tura, Bernardo Rangel; Ziemer, Paulo Gustavo Portela; Blanco, Pablo Javier; Pina, Gustavo; Meira, Márcio; Souza e Silva, Nelson Albuquerque de

    2012-10-01

    The standardization of images used in Medicine in 1993 was performed using the DICOM (Digital Imaging and Communications in Medicine) standard. Several tests use this standard and it is increasingly necessary to design software applications capable of handling this type of image; however, these software applications are not usually free and open-source, and this fact hinders their adjustment to most diverse interests. To develop and validate a free and open-source software application capable of handling DICOM coronary computed tomography angiography images. We developed and tested the ImageLab software in the evaluation of 100 tests randomly selected from a database. We carried out 600 tests divided between two observers using ImageLab and another software sold with Philips Brilliance computed tomography appliances in the evaluation of coronary lesions and plaques around the left main coronary artery (LMCA) and the anterior descending artery (ADA). To evaluate intraobserver, interobserver and intersoftware agreements, we used simple and kappa statistics agreements. The agreements observed between software applications were generally classified as substantial or almost perfect in most comparisons. The ImageLab software agreed with the Philips software in the evaluation of coronary computed tomography angiography tests, especially in patients without lesions, with lesions 70% in the ADA was lower, but this is also observed when the anatomical reference standard is used.

  19. TH-CD-207B-01: BEST IN PHYSICS (IMAGING): Development of High Brightness Multiple-Pixel X-Ray Source Using Oxide Coated Cathodes

    Kandlakunta, P; Pham, R; Zhang, T

    2016-01-01

    Purpose: To develop and characterize a high brightness multiple-pixel thermionic emission x-ray (MPTEX) source. Methods: Multiple-pixel x-ray sources allow for designs of novel x-ray imaging techniques, such as fixed gantry CT, digital tomosynthesis, tetrahedron beam computed tomography, etc. We are developing a high-brightness multiple-pixel thermionic emission x-ray (MPTEX) source based on oxide coated cathodes. Oxide cathode is chosen as the electron source due to its high emission current density and low operating temperature. A MPTEX prototype has been developed which may contain up to 41 micro-rectangular oxide cathodes in 4 mm pixel spacing. Electronics hardware was developed for source control and switching. The cathode emission current was evaluated and x-ray measurements were performed to estimate the focal spot size. Results: The oxide cathodes were able to produce ∼110 mA cathode current in pulse mode which corresponds to an emission current density of 0.55 A/cm 2 . The maximum kVp of the MPTEX prototype currently is limited to 100 kV due to the rating of high voltage feedthrough. Preliminary x-ray measurements estimated the focal spot size as 1.5 × 1.3 mm 2 . Conclusion: A MPTEX source was developed with thermionic oxide coated cathodes and preliminary source characterization was successfully performed. The MPTEX source is able to produce an array of high brightness x-ray beams with a fast switching speed.

  20. Topography, power, and current source density of θ oscillations during reward processing as markers for alcohol dependence.

    Kamarajan, Chella; Rangaswamy, Madhavi; Manz, Niklas; Chorlian, David B; Pandey, Ashwini K; Roopesh, Bangalore N; Porjesz, Bernice

    2012-05-01

    Recent studies have linked alcoholism with a dysfunctional neural reward system. Although several electrophysiological studies have explored reward processing in healthy individuals, such studies in alcohol-dependent individuals are quite rare. The present study examines theta oscillations during reward processing in abstinent alcoholics. The electroencephalogram (EEG) was recorded in 38 abstinent alcoholics and 38 healthy controls as they performed a single outcome gambling task, which involved outcomes of either loss or gain of an amount (10 or 50¢) that was bet. Event-related theta band (3.0-7.0 Hz) power following each outcome stimulus was computed using the S-transform method. Theta power at the time window of the outcome-related negativity (ORN) and positivity (ORP) (200-500 ms) was compared across groups and outcome conditions. Additionally, behavioral data of impulsivity and task performance were analyzed. The alcoholic group showed significantly decreased theta power during reward processing compared to controls. Current source density (CSD) maps of alcoholics revealed weaker and diffuse source activity for all conditions and weaker bilateral prefrontal sources during the Loss 50 condition when compared with controls who manifested stronger and focused midline sources. Furthermore, alcoholics exhibited increased impulsivity and risk-taking on the behavioral measures. A strong association between reduced anterior theta power and impulsive task-performance was observed. It is suggested that decreased power and weaker and diffuse CSD in alcoholics may be due to dysfunctional neural reward circuitry. The relationship among alcoholism, theta oscillations, reward processing, and impulsivity could offer clues to understand brain circuitries that mediate reward processing and inhibitory control. Copyright © 2011 Wiley-Liss, Inc.

  1. Exogenous contrast agents for thermoacoustic imaging: An investigation into the underlying sources of contrast

    Ogunlade, Olumide; Beard, Paul

    2015-01-01

    Purpose: Thermoacoustic imaging at microwave excitation frequencies is limited by the low differential contrast exhibited by high water content tissues. To overcome this, exogenous thermoacoustic contrast agents based on gadolinium compounds, iron oxide, and single wall carbon nanotubes have previously been suggested and investigated. However, these previous studies did not fully characterize the electric, magnetic, and thermodynamic properties of these agents thus precluding identification of the underlying sources of contrast. To address this, measurements of the complex permittivity, complex permeability, DC conductivity, and Grüneisen parameter have been made. These measurements allowed the origins of the contrast provided by each substance to be identified. Methods: The electric and magnetic properties of the contrast agents were characterized at 3 GHz using two rectangular waveguide cavities. The DC conductivity was measured separately using a conductivity meter. Thermoacoustic signals were then acquired and compared to those generated in water. Finally, 3D electromagnetic simulations were used to decouple the different contributions to the absorbed power density. Results: It was found that the gadolinium compounds provided appreciable electric contrast but not originating from the gadolinium itself. The contrast was either due to dissociation of the gadolinium salt which increased ionic conductivity or its nondissociated polar fraction which increased dielectric polarization loss or a combination of both. In addition, very high concentrations were required to achieve appreciable contrast, to the extent that the Grüneisen parameter increased significantly and became a source of contrast. Iron oxide particles were found to produce low but measurable dielectric contrast due to dielectric polarization loss, but this is attributed to the coating of the particles not the iron oxide. Single wall carbon nanotubes did not provide measurable contrast of any type

  2. Exogenous contrast agents for thermoacoustic imaging: An investigation into the underlying sources of contrast

    Ogunlade, Olumide, E-mail: o.ogunlade@ucl.ac.uk; Beard, Paul [Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT (United Kingdom)

    2015-01-15

    Purpose: Thermoacoustic imaging at microwave excitation frequencies is limited by the low differential contrast exhibited by high water content tissues. To overcome this, exogenous thermoacoustic contrast agents based on gadolinium compounds, iron oxide, and single wall carbon nanotubes have previously been suggested and investigated. However, these previous studies did not fully characterize the electric, magnetic, and thermodynamic properties of these agents thus precluding identification of the underlying sources of contrast. To address this, measurements of the complex permittivity, complex permeability, DC conductivity, and Grüneisen parameter have been made. These measurements allowed the origins of the contrast provided by each substance to be identified. Methods: The electric and magnetic properties of the contrast agents were characterized at 3 GHz using two rectangular waveguide cavities. The DC conductivity was measured separately using a conductivity meter. Thermoacoustic signals were then acquired and compared to those generated in water. Finally, 3D electromagnetic simulations were used to decouple the different contributions to the absorbed power density. Results: It was found that the gadolinium compounds provided appreciable electric contrast but not originating from the gadolinium itself. The contrast was either due to dissociation of the gadolinium salt which increased ionic conductivity or its nondissociated polar fraction which increased dielectric polarization loss or a combination of both. In addition, very high concentrations were required to achieve appreciable contrast, to the extent that the Grüneisen parameter increased significantly and became a source of contrast. Iron oxide particles were found to produce low but measurable dielectric contrast due to dielectric polarization loss, but this is attributed to the coating of the particles not the iron oxide. Single wall carbon nanotubes did not provide measurable contrast of any type

  3. Transfer standard for the spectral density of relative intensity noise of optical fiber sources near 1550 nm

    Obarski, Gregory E.; Splett, Jolene D.

    2001-01-01

    We have developed a transfer standard for the spectral density of relative intensity noise (RIN) of optical fiber sources near 1550 nm. Amplified spontaneous emission (ASE) from an erbium-doped fiber amplifier (EDFA), when it is optically filtered over a narrow band (<5 nm), yields a stable RIN spectrum that is practically constant to several tens of gigahertz. The RIN is calculated from the power spectral density as measured with a calibrated optical spectrum analyzer. For a typical device it is -110 dB/Hz, with uncertainty ≤0.12 dB/Hz. The invariance of the RIN under attenuation yields a considerable dynamic range with respect to rf noise levels. Results are compared with those from a second method that uses a distributed-feedback laser (DFB) that has a Poisson-limited RIN. Application of each method to the same RIN measurement system yields frequency-dependent calibration functions that, when they are averaged, differ by ≤0.2 dB. [copyright] 2001 Optical Society of America

  4. Transfer standard for the spectral density of relative intensity noise of optical fiber sources near 1550 nm

    Obarski, Gregory E.; Splett, Jolene D.

    2001-06-01

    We have developed a transfer standard for the spectral density of relative intensity noise (RIN) of optical fiber sources near 1550 nm. Amplified spontaneous emission (ASE) from an erbium-doped fiber amplifier (EDFA), when it is optically filtered over a narrow band ({lt}5 nm), yields a stable RIN spectrum that is practically constant to several tens of gigahertz. The RIN is calculated from the power spectral density as measured with a calibrated optical spectrum analyzer. For a typical device it is {minus}110 dB/Hz, with uncertainty {le}0.12 dB/Hz. The invariance of the RIN under attenuation yields a considerable dynamic range with respect to rf noise levels. Results are compared with those from a second method that uses a distributed-feedback laser (DFB) that has a Poisson-limited RIN. Application of each method to the same RIN measurement system yields frequency-dependent calibration functions that, when they are averaged, differ by {le}0.2 dB. {copyright} 2001 Optical Society of America

  5. Optical and near-infrared imaging of faint Gigahertz Peaked Spectrum sources

    Snellen, IAG; Schilizzi, RT; de Bruyn, AG; Miley, GK; Rottgering, HJA; McMahon, RG; Fournon, IP

    1998-01-01

    A sample of 47 faint Gigahertz Peaked Spectrum (GPS) radio sources selected from the Westerbork Northern Sky Survey (WENSS) has been imaged in the optical and near-infrared, resulting in an identification fraction of 87 per cent. The R - I and R - K colours of the faint optical counterparts are as

  6. Probabilistic M/EEG source imaging from sparse spatio-temporal event structure

    Stahlhut, Carsten; Attias, Hagai T.; Wipf, David

    While MEG and EEG source imaging methods have to tackle a severely ill-posed problem their success can be stated as their ability to constrain the solutions using appropriate priors. In this paper we propose a hierarchical Bayesian model facilitating spatio-temporal patterns through the use of bo...

  7. Open source deformable image registration system for treatment planning and recurrence CT scans

    Zukauskaite, Ruta; Brink, Carsten; Hansen, Christian Rønn

    2016-01-01

    manually contoured eight anatomical regions-of-interest (ROI) twice on pCT and once on rCT. METHODS: pCT and rCT images were deformably registered using the open source software elastix. Mean surface distance (MSD) and Dice similarity coefficient (DSC) between contours were used for validation of DIR...

  8. A combination of the acoustic radiosity and the image source method

    Koutsouris, Georgios I.; Brunskog, Jonas; Jeong, Cheol-Ho

    2012-01-01

    A combined model for room acoustic predictions is developed, aiming to treat both diffuse and specular reflections in a unified way. Two established methods are incorporated: acoustical radiosity, accounting for the diffuse part, and the image source method, accounting for the specular part...

  9. Comparing a phased combination of acoustical radiosity and the image source method with other simulation tools

    Marbjerg, Gerd Høy; Brunskog, Jonas; Jeong, Cheol-Ho

    2015-01-01

    A phased combination of acoustical radiosity and the image source method (PARISM) has been developed in order to be able to model both specular and diffuse reflections with angle-dependent and complex-valued acoustical descriptions of the surfaces. It is of great interest to model both specular...

  10. Incorporating Open Source Data for Bayesian Classification of Urban Land Use From VHR Stereo Images

    Li, Mengmeng; De Beurs, Kirsten M.; Stein, Alfred; Bijker, Wietske

    2017-01-01

    This study investigates the incorporation of open source data into a Bayesian classification of urban land use from very high resolution (VHR) stereo satellite images. The adopted classification framework starts from urban land cover classification, proceeds to building-type characterization, and

  11. Application of Multi-Source Remote Sensing Image in Yunnan Province Grassland Resources Investigation

    Li, J.; Wen, G.; Li, D.

    2018-04-01

    Trough mastering background information of Yunnan province grassland resources utilization and ecological conditions to improves grassland elaborating management capacity, it carried out grassland resource investigation work by Yunnan province agriculture department in 2017. The traditional grassland resource investigation method is ground based investigation, which is time-consuming and inefficient, especially not suitable for large scale and hard-to-reach areas. While remote sensing is low cost, wide range and efficient, which can reflect grassland resources present situation objectively. It has become indispensable grassland monitoring technology and data sources and it has got more and more recognition and application in grassland resources monitoring research. This paper researches application of multi-source remote sensing image in Yunnan province grassland resources investigation. First of all, it extracts grassland resources thematic information and conducts field investigation through BJ-2 high space resolution image segmentation. Secondly, it classifies grassland types and evaluates grassland degradation degree through high resolution characteristics of Landsat 8 image. Thirdly, it obtained grass yield model and quality classification through high resolution and wide scanning width characteristics of MODIS images and sample investigate data. Finally, it performs grassland field qualitative analysis through UAV remote sensing image. According to project area implementation, it proves that multi-source remote sensing data can be applied to the grassland resources investigation in Yunnan province and it is indispensable method.

  12. Characterization of dynamic changes of current source localization based on spatiotemporal fMRI constrained EEG source imaging

    Nguyen, Thinh; Potter, Thomas; Grossman, Robert; Zhang, Yingchun

    2018-06-01

    Objective. Neuroimaging has been employed as a promising approach to advance our understanding of brain networks in both basic and clinical neuroscience. Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) represent two neuroimaging modalities with complementary features; EEG has high temporal resolution and low spatial resolution while fMRI has high spatial resolution and low temporal resolution. Multimodal EEG inverse methods have attempted to capitalize on these properties but have been subjected to localization error. The dynamic brain transition network (DBTN) approach, a spatiotemporal fMRI constrained EEG source imaging method, has recently been developed to address these issues by solving the EEG inverse problem in a Bayesian framework, utilizing fMRI priors in a spatial and temporal variant manner. This paper presents a computer simulation study to provide a detailed characterization of the spatial and temporal accuracy of the DBTN method. Approach. Synthetic EEG data were generated in a series of computer simulations, designed to represent realistic and complex brain activity at superficial and deep sources with highly dynamical activity time-courses. The source reconstruction performance of the DBTN method was tested against the fMRI-constrained minimum norm estimates algorithm (fMRIMNE). The performances of the two inverse methods were evaluated both in terms of spatial and temporal accuracy. Main results. In comparison with the commonly used fMRIMNE method, results showed that the DBTN method produces results with increased spatial and temporal accuracy. The DBTN method also demonstrated the capability to reduce crosstalk in the reconstructed cortical time-course(s) induced by neighboring regions, mitigate depth bias and improve overall localization accuracy. Significance. The improved spatiotemporal accuracy of the reconstruction allows for an improved characterization of complex neural activity. This improvement can be

  13. Air density dependence of the response of the PTW SourceCheck 4pi ionization chamber for 125I brachytherapy seeds.

    Torres Del Río, J; Tornero-López, A M; Guirado, D; Pérez-Calatayud, J; Lallena, A M

    2017-06-01

    To analyze the air density dependence of the response of the new SourceCheck 4pi ionization chamber, manufactured by PTW. The air density dependence of three different SourceCheck 4pi chambers was studied by measuring 125 I sources. Measurements were taken by varying the pressure from 746.6 to 986.6hPa in a pressure chamber. Three different HDR 1000 Plus ionization chambers were also analyzed under similar conditions. A linear and a potential-like function of the air density were fitted to experimental data and their achievement in describing them was analyzed. SourceCheck 4pi chamber response showed a residual dependence on the air density once the standard pressure and temperature factor was applied. The chamber response was overestimated when the air density was below that under normal atmospheric conditions. A similar dependence was found for the HDR 1000 Plus chambers analyzed. A linear function of the air density permitted a very good description of this residual dependence, better than with a potential function. No significant variability between the different specimens of the same chamber model studied was found. The effect of overestimation observed in the chamber responses once they are corrected for the standard pressure and temperature may represent a non-negligible ∼4% overestimation in high altitude cities as ours (700m AMSL). This overestimation behaves linearly with the air density in all cases analyzed. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  14. Demonstration of acoustic source localization in air using single pixel compressive imaging

    Rogers, Jeffrey S.; Rohde, Charles A.; Guild, Matthew D.; Naify, Christina J.; Martin, Theodore P.; Orris, Gregory J.

    2017-12-01

    Acoustic source localization often relies on large sensor arrays that can be electronically complex and have large data storage requirements to process element level data. Recently, the concept of a single-pixel-imager has garnered interest in the electromagnetics literature due to its ability to form high quality images with a single receiver paired with shaped aperture screens that allow for the collection of spatially orthogonal measurements. Here, we present a method for creating an acoustic analog to the single-pixel-imager found in electromagnetics for the purpose of source localization. Additionally, diffraction is considered to account for screen openings comparable to the acoustic wavelength. A diffraction model is presented and incorporated into the single pixel framework. In this paper, we explore the possibility of applying single pixel localization to acoustic measurements. The method is experimentally validated with laboratory measurements made in an air waveguide.

  15. The correlationship between mandibular radiomorphometric indices in panorama and bone mineral density in Cu-equivalent image of intraoral film

    Kim, Jae Duk

    2003-01-01

    To determine whether the mandibular radiomorphometric indices in panoramic radiography are correlated with the bone mineral density of Cu-equivalent images in intraoral film. The bone mineral density (BMD) of the mandibular premolar area was measured in the Cu-equivalent image of intraoral film. The Panoramic Mandibular Index (PMI) and Mandibular Cortical Width (MCW) were measured in panoramic radiographs of six dry mandibles, and the Pearson correlation between PMI, MCW, and BMD were tested. There were no significant correlations between PMI and BMD (r=0.280), nor between MCW and BMD (r=0.237). The results show that PMI and MCW were poor diagnostic indicators of mandibular BMD in the six dry mandibles used in this study. The correlationship between the mandibular radiomorphometric indices (PMI and MCW) and mandibular BMD needs to be researched further using large in vivo patient samples.

  16. Image features dependant correlation-weighting function for efficient PRNU based source camera identification.

    Tiwari, Mayank; Gupta, Bhupendra

    2018-04-01

    For source camera identification (SCI), photo response non-uniformity (PRNU) has been widely used as the fingerprint of the camera. The PRNU is extracted from the image by applying a de-noising filter then taking the difference between the original image and the de-noised image. However, it is observed that intensity-based features and high-frequency details (edges and texture) of the image, effect quality of the extracted PRNU. This effects correlation calculation and creates problems in SCI. For solving this problem, we propose a weighting function based on image features. We have experimentally identified image features (intensity and high-frequency contents) effect on the estimated PRNU, and then develop a weighting function which gives higher weights to image regions which give reliable PRNU and at the same point it gives comparatively less weights to the image regions which do not give reliable PRNU. Experimental results show that the proposed weighting function is able to improve the accuracy of SCI up to a great extent. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Spectro-refractometry of individual microscopic objects using swept-source quantitative phase imaging.

    Jung, Jae-Hwang; Jang, Jaeduck; Park, Yongkeun

    2013-11-05

    We present a novel spectroscopic quantitative phase imaging technique with a wavelength swept-source, referred to as swept-source diffraction phase microscopy (ssDPM), for quantifying the optical dispersion of microscopic individual samples. Employing the swept-source and the principle of common-path interferometry, ssDPM measures the multispectral full-field quantitative phase imaging and spectroscopic microrefractometry of transparent microscopic samples in the visible spectrum with a wavelength range of 450-750 nm and a spectral resolution of less than 8 nm. With unprecedented precision and sensitivity, we demonstrate the quantitative spectroscopic microrefractometry of individual polystyrene beads, 30% bovine serum albumin solution, and healthy human red blood cells.

  18. Affective attitudes to face images associated with intracerebral EEG source location before face viewing.

    Pizzagalli, D; Koenig, T; Regard, M; Lehmann, D

    1999-01-01

    We investigated whether different, personality-related affective attitudes are associated with different brain electric field (EEG) sources before any emotional challenge (stimulus exposure). A 27-channel EEG was recorded in 15 subjects during eyes-closed resting. After recording, subjects rated 32 images of human faces for affective appeal. The subjects in the first (i.e., most negative) and fourth (i.e., most positive) quartile of general affective attitude were further analyzed. The EEG data (mean=25+/-4. 8 s/subject) were subjected to frequency-domain model dipole source analysis (FFT-Dipole-Approximation), resulting in 3-dimensional intracerebral source locations and strengths for the delta-theta, alpha, and beta EEG frequency band, and for the full range (1.5-30 Hz) band. Subjects with negative attitude (compared to those with positive attitude) showed the following source locations: more inferior for all frequency bands, more anterior for the delta-theta band, more posterior and more right for the alpha, beta and 1.5-30 Hz bands. One year later, the subjects were asked to rate the face images again. The rating scores for the same face images were highly correlated for all subjects, and original and retest affective mean attitude was highly correlated across subjects. The present results show that subjects with different affective attitudes to face images had different active, cerebral, neural populations in a task-free condition prior to viewing the images. We conclude that the brain functional state which implements affective attitude towards face images as a personality feature exists without elicitors, as a continuously present, dynamic feature of brain functioning. Copyright 1999 Elsevier Science B.V.

  19. Imaging of exploding wire plasmas by high-luminosity monochromatic X-ray backlighting using an X-pinch radiation source

    Pikuz, S A; Shelkovenko, T A; Romanova, V M [Russian Academy of Sciences, Moscow (Russian Federation). P.N. Lebedev Physical Inst.; Hammer, D A [Cornell Univ., Ithaca, NY (United States). Laboratory of Plasma Studies; Faenov, A Ya; Pikuz, T A [VNIIFTRI, Mendeleevo (Russian Federation). Multicharged Ions Spectral Data Center

    1997-12-31

    A new diagnostic method for dense plasmas, monochromatic x-ray backlighting, is described. In this method, shadow images of a bright, dense plasma can be obtained with high spatial resolution using monochromatic radiation from a separate plasma, permitting a major reduction in the required backlighting source power. The object plasma is imaged utilizing spherically bent mica crystals as the x-ray optical elements. Images of test objects obtained using x-ray radiation having different photon energies are presented. Shadow images of exploding Al wire plasmas in the ls{sup 2}-1s3p line radiation of He-like Al XII are also shown. Spatial resolution as fine as 4 {mu}m is demonstrated. The scheme described is useful for backlighting extended high density plasmas, and could be a less costly alternative to using X-ray lasers for such purposes. (author). 7 figs., 10 refs.

  20. Density characterization of radiochromic film through source axis distance (SAD) technique in linac with slab phantom for radiotherapy applications

    Hariani, Yousida; Haris, Bambang

    2017-05-01

    Characterization of radiochromic film density is accomplished through Source Axis Distance (SAD) technique in a slab phantom Linac with various depths and breadths of field. Type of the film used is gafchromic RTQA2. The dose of radiation exposure of the film may cause changes in the film density. This research aims to determine the relation between the density and the dose depth through the characteristic of curves to identify the depth of the dose and particular breadth of the field as a reference for the dose of radiotherapy patients. The result shows that the higher the dose is absorbed, the darker the film will be, yet the lower the density is obtained. The dose depth is determined by measuring the amount of dose received at various depths and breadths of field using film that is placed on the slab phantom with 6 MV linac radiation and dose of 300 cGy. The variation of the depth at 1.5 cm; 4 cm; 6 cm; 8 cm; 10 cm, the field size at 4 × 4 cm2, and the dose depth at 359.7 cGy; 315.3 cGy; 281.4 cGy; 241.2 cGy; 220.5 cGy were settled. The field size 6 × 6 cm2 takes the dose depth 354.6 cGy; 314.1 cGy; 282.6 cGy; 244.5 cGy; 224.7 cGy. The field size 8 × 8 cm2 takes the dose depth 351.6 cGy; 313 cGy; 283.8 cGy; 247.2 cGy; 228 cGy. The field size 10 × 10 cm2 takes the dose depth 348.9 cGy; 342.6 cGy; 248.4 cGy; 249.6 cGy; 231 cGy.

  1. Density characterization of radiochromic film through source axis distance (SAD) technique in linac with slab phantom for radiotherapy applications

    Hariani, Yousida; Haris, Bambang

    2017-01-01

    Characterization of radiochromic film density is accomplished through Source Axis Distance (SAD) technique in a slab phantom Linac with various depths and breadths of field. Type of the film used is gafchromic RTQA2. The dose of radiation exposure of the film may cause changes in the film density. This research aims to determine the relation between the density and the dose depth through the characteristic of curves to identify the depth of the dose and particular breadth of the field as a reference for the dose of radiotherapy patients. The result shows that the higher the dose is absorbed, the darker the film will be, yet the lower the density is obtained. The dose depth is determined by measuring the amount of dose received at various depths and breadths of field using film that is placed on the slab phantom with 6 MV linac radiation and dose of 300 cGy. The variation of the depth at 1.5 cm; 4 cm; 6 cm; 8 cm; 10 cm, the field size at 4 × 4 cm 2 , and the dose depth at 359.7 cGy; 315.3 cGy; 281.4 cGy; 241.2 cGy; 220.5 cGy were settled. The field size 6 × 6 cm 2 takes the dose depth 354.6 cGy; 314.1 cGy; 282.6 cGy; 244.5 cGy; 224.7 cGy. The field size 8 × 8 cm 2 takes the dose depth 351.6 cGy; 313 cGy; 283.8 cGy; 247.2 cGy; 228 cGy. The field size 10 × 10 cm 2 takes the dose depth 348.9 cGy; 342.6 cGy; 248.4 cGy; 249.6 cGy; 231 cGy. (paper)

  2. Beyond seismic interferometry: imaging the earth's interior with virtual sources and receivers inside the earth

    Wapenaar, C. P. A.; Van der Neut, J.; Thorbecke, J.; Broggini, F.; Slob, E. C.; Snieder, R.

    2015-12-01

    Imagine one could place seismic sources and receivers at any desired position inside the earth. Since the receivers would record the full wave field (direct waves, up- and downward reflections, multiples, etc.), this would give a wealth of information about the local structures, material properties and processes in the earth's interior. Although in reality one cannot place sources and receivers anywhere inside the earth, it appears to be possible to create virtual sources and receivers at any desired position, which accurately mimics the desired situation. The underlying method involves some major steps beyond standard seismic interferometry. With seismic interferometry, virtual sources can be created at the positions of physical receivers, assuming these receivers are illuminated isotropically. Our proposed method does not need physical receivers at the positions of the virtual sources; moreover, it does not require isotropic illumination. To create virtual sources and receivers anywhere inside the earth, it suffices to record the reflection response with physical sources and receivers at the earth's surface. We do not need detailed information about the medium parameters; it suffices to have an estimate of the direct waves between the virtual-source positions and the acquisition surface. With these prerequisites, our method can create virtual sources and receivers, anywhere inside the earth, which record the full wave field. The up- and downward reflections, multiples, etc. in the virtual responses are extracted directly from the reflection response at the surface. The retrieved virtual responses form an ideal starting point for accurate seismic imaging, characterization and monitoring.

  3. Preliminary Results of Nuclear Fluorescence Imaging of Alpha and Beta Emitting Sources

    Feener, Jessica S.; Charlton, William S.

    2013-06-01

    The preliminary results from a series of nuclear fluorescence imaging experiments using a variety of radioactive sources and shielding are given. These experiments were done as part of a proof of concept to determine if nuclear fluorescence imaging could be used as a safeguards measurements tool or for nuclear warhead verification for nuclear arms control treaties such as the New Strategic Arms Reduction Treaty and the Fissile Material Cut-Off Treaty. An off-the-shelf Princeton Instruments charged coupled device camera system was used to image the emission of fluorescence photons from the de-excitation of nitrogen molecules in air that have been excited by ionizing radiation. The fluorescence emissions are primarily in the near ultraviolet range; between the wavelengths of 300 and 400 nm. Fluorescent imaging techniques are currently being investigated in a number of applications. A French research team has successfully demonstrated this concept for remote imaging of alpha contamination. It has also been shown that the phenomenon can be seen through translucent materials and that alpha radiation can be seen in the presence of large gamma backgrounds. Additionally, fluorescence telescopes and satellites utilize the de-excitation of nitrogen molecules to observe cosmic ray showers in the atmosphere. In cosmic ray shower detection, electrons are the main contributor to the excitation of the of nitrogen molecules in air. The experiments presented in this paper were designed to determine if the imaging system could observe beta emitting sources, differentiate between beta emitters and alpha emitting materials such as uranium oxide and uranium metal, and to further investigate the phenomenon through translucent and non-translucent materials. The initial results show that differentiation can be made between beta and alpha emitting sources and that the device can observe the phenomenon through very thin non-transparent material. Additionally, information is given on the

  4. Integration of EEG source imaging and fMRI during continuous viewing of natural movies.

    Whittingstall, Kevin; Bartels, Andreas; Singh, Vanessa; Kwon, Soyoung; Logothetis, Nikos K

    2010-10-01

    Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are noninvasive neuroimaging tools which can be used to measure brain activity with excellent temporal and spatial resolution, respectively. By combining the neural and hemodynamic recordings from these modalities, we can gain better insight into how and where the brain processes complex stimuli, which may be especially useful in patients with different neural diseases. However, due to their vastly different spatial and temporal resolutions, the integration of EEG and fMRI recordings is not always straightforward. One fundamental obstacle has been that paradigms used for EEG experiments usually rely on event-related paradigms, while fMRI is not limited in this regard. Therefore, here we ask whether one can reliably localize stimulus-driven EEG activity using the continuously varying feature intensities occurring in natural movie stimuli presented over relatively long periods of time. Specifically, we asked whether stimulus-driven aspects in the EEG signal would be co-localized with the corresponding stimulus-driven BOLD signal during free viewing of a movie. Secondly, we wanted to integrate the EEG signal directly with the BOLD signal, by estimating the underlying impulse response function (IRF) that relates the BOLD signal to the underlying current density in the primary visual area (V1). We made sequential fMRI and 64-channel EEG recordings in seven subjects who passively watched 2-min-long segments of a James Bond movie. To analyze EEG data in this natural setting, we developed a method based on independent component analysis (ICA) to reject EEG artifacts due to blinks, subject movement, etc., in a way unbiased by human judgment. We then calculated the EEG source strength of this artifact-free data at each time point of the movie within the entire brain volume using low-resolution electromagnetic tomography (LORETA). This provided for every voxel in the brain (i.e., in 3D space) an

  5. An image-based search for pulsars among Fermi unassociated LAT sources

    Frail, D. A.; Ray, P. S.; Mooley, K. P.; Hancock, P.; Burnett, T. H.; Jagannathan, P.; Ferrara, E. C.; Intema, H. T.; de Gasperin, F.; Demorest, P. B.; Stovall, K.; McKinnon, M. M.

    2018-03-01

    We describe an image-based method that uses two radio criteria, compactness, and spectral index, to identify promising pulsar candidates among Fermi Large Area Telescope (LAT) unassociated sources. These criteria are applied to those radio sources from the Giant Metrewave Radio Telescope all-sky survey at 150 MHz (TGSS ADR1) found within the error ellipses of unassociated sources from the 3FGL catalogue and a preliminary source list based on 7 yr of LAT data. After follow-up interferometric observations to identify extended or variable sources, a list of 16 compact, steep-spectrum candidates is generated. An ongoing search for pulsations in these candidates, in gamma rays and radio, has found 6 ms pulsars and one normal pulsar. A comparison of this method with existing selection criteria based on gamma-ray spectral and variability properties suggests that the pulsar discovery space using Fermi may be larger than previously thought. Radio imaging is a hitherto underutilized source selection method that can be used, as with other multiwavelength techniques, in the search for Fermi pulsars.

  6. Simulation of an IXS imaging analyzer with an extended scattering source

    Suvorov, Alexey [Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II; Cai, Yong Q. [Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II

    2016-09-15

    A concept of an inelastic x-ray scattering (IXS) spectrograph with an imaging analyzer was proposed recently and discussed in a number of publications (see e.g. Ref.1). The imaging analyzer as proposed combines x-ray lenses with highly dispersive crystal optics. It allows conversion of the x-ray energy spectrum into a spatial image with very high energy resolution. However, the presented theoretical analysis of the spectrograph did not take into account details of the scattered radiation source, i.e. sample, and its impact on the spectrograph performance. Using numerical simulations we investigated the influence of the finite sample thickness, the scattering angle and the incident energy detuning on the analyzer image and the ultimate resolution.

  7. Image acquisition and analysis for beam diagnostics, applications of the Taiwan photon source

    Liao, C.Y.; Chen, J.; Cheng, Y.S.; Hsu, K.T.; Hu, K.H.; Kuo, C.H.; Wu, C.Y.

    2012-01-01

    Design and implementation of image acquisition and analysis is in proceeding for the Taiwan Photon Source (TPS) diagnostic applications. The optical system contains screen, lens, and lighting system. A CCD camera with Gigabit Ethernet interface (GigE Vision) will be a standard image acquisition device. Image acquisition will be done on EPICS IOC via PV channel and analysis the properties by using Matlab tool to evaluate the beam profile (sigma), beam size position and tilt angle et al. The EPICS IOC integrated with Matlab as a data processing system is not only could be used in image analysis but also in many types of equipment data processing applications. Progress of the project will be summarized in this report. (authors)

  8. Estimates of Imaging Times for Conventional and Synchrotron X-Ray Sources

    Kinney, J

    2003-01-01

    The following notes are to be taken as estimates of the time requirements for imaging NIF targets in three-dimensions with absorption contrast. The estimates ignore target geometry and detector inefficiency, and focus only on the statistical question of detecting compositional (structural) differences between adjacent volume elements in the presence of noise. The basic equations, from the classic reference by Grodzins, consider imaging times in terms of the required number of photons necessary to provide an image with given resolution and noise. The time estimates, therefore, have been based on the calculated x-ray fluxes from the proposed Advanced Light Source (ALS) imaging beamline, and from the calculated flux for a tungsten anode x-ray generator operated in a point focus mode.

  9. A tunable continuous wave (CW) and short-pulse optical source for THz brain imaging applications

    Bakopoulos, P; Karanasiou, I; Zakynthinos, P; Uzunoglu, N; Avramopoulos, H; Pleros, N

    2009-01-01

    We demonstrate recent advances toward the development of a novel 2D THz imaging system for brain imaging applications both at the macroscopic and at the bimolecular level. A frequency-synthesized THz source based on difference frequency generation between optical wavelengths is presented, utilizing supercontinuum generation in a highly nonlinear optical fiber with subsequent spectral carving by means of a fiber Fabry–Perot filter. Experimental results confirm the successful generation of THz radiation in the range of 0.2–2 THz, verifying the enhanced frequency tunability properties of the proposed system. Finally, the roadmap toward capturing functional brain information by exploiting THz imaging technologies is discussed, outlining the unique advantages offered by THz frequencies and their complementarity with existing brain imaging techniques

  10. Technique for fabrication of gradual standards of radiographic image blachening density

    Borovin, I.V.; Kondina, M.A.

    1987-01-01

    The technique of fabrication of gradual standards of blackening density for industrial radiography by contact printing from a negative is described. The technique is designed for possibilities of industrial laboratoriesof radiation defectoscopy possessing no special-purpose sensitometric equipment

  11. Imaging Seismic Source Variations Using Back-Projection Methods at El Tatio Geyser Field, Northern Chile

    Kelly, C. L.; Lawrence, J. F.

    2014-12-01

    During October 2012, 51 geophones and 6 broadband seismometers were deployed in an ~50x50m region surrounding a periodically erupting columnar geyser in the El Tatio Geyser Field, Chile. The dense array served as the seismic framework for a collaborative project to study the mechanics of complex hydrothermal systems. Contemporaneously, complementary geophysical measurements (including down-hole temperature and pressure, discharge rates, thermal imaging, water chemistry, and video) were also collected. Located on the western flanks of the Andes Mountains at an elevation of 4200m, El Tatio is the third largest geyser field in the world. Its non-pristine condition makes it an ideal location to perform minutely invasive geophysical studies. The El Jefe Geyser was chosen for its easily accessible conduit and extremely periodic eruption cycle (~120s). During approximately 2 weeks of continuous recording, we recorded ~2500 nighttime eruptions which lack cultural noise from tourism. With ample data, we aim to study how the source varies spatially and temporally during each phase of the geyser's eruption cycle. We are developing a new back-projection processing technique to improve source imaging for diffuse signals. Our method was previously applied to the Sierra Negra Volcano system, which also exhibits repeating harmonic and diffuse seismic sources. We back-project correlated seismic signals from the receivers back to their sources, assuming linear source to receiver paths and a known velocity model (obtained from ambient noise tomography). We apply polarization filters to isolate individual and concurrent geyser energy associated with P and S phases. We generate 4D, time-lapsed images of the geyser source field that illustrate how the source distribution changes through the eruption cycle. We compare images for pre-eruption, co-eruption, post-eruption and quiescent periods. We use our images to assess eruption mechanics in the system (i.e. top-down vs. bottom-up) and

  12. Magnetic resonance imaging. Density equalizing mapping analysis of global research architecture; Magnetresonanztomographie. Eine Density-equalizing-mapping-Analyse der globalen Forschungsarchitektur

    Ohlendorf, D.; Schwarze, B.; Groneberg, D.A.; Schwarzer, M. [Goethe-Universitaet Frankfurt/M, Institut fuer Arbeitsmedizin, Sozialmedizin und Umweltmedizin, Frankfurt/M (Germany)

    2015-09-15

    Despite the great medical importance, there is still no comprehensive scientometric analysis regarding the results of magnetic resonance imaging (MRI) and the development of the importance for the healthcare system. This paper evaluated and analyzed the entire research publication results on the topic of MRI for the period 1981-2007 based on scientometric methods and parameters. A scientometric analysis (database: ISI Web of Science 1981-2007, search terms MRI and magnetic resonance imaging) was performed. The following parameters were analyzed: number of publications, countries of publication, number of citations, citation rate and collaborations, using various analytical and display techniques, including density equalizing map projections. Most of the 49,122 publications on MRI could be attributed to the USA (32.5 %), which also has the most cooperative collaborations. Within Europe, Germany (10.3 %) is the country with the highest number of publications followed by the UK (9.3 %). The western industrialized nations dominate over the rest of the world in terms of scientific developments of MRI. The thematic focus of the publications lies in the fields of radiology and neuroscience. In addition to the journal Neurology most scientific articles were published in Magnetic Resonance in Medicine and Circulation. The results show that the current trend is continuing and the scientific interest in MRI is continuously increasing. (orig.) [German] Trotz der grossen medizinischen Bedeutung existiert bis heute keine umfassende szientometrische Analyse bzgl. der Forschungsergebnisse zur Magnetresonanztomographie (MRT) und der Entwicklung ihrer Bedeutung fuer das Gesundheitssystem. Im vorliegenden Beitrag soll anhand szientometrischer Methoden und Parameter das gesamte Forschungsaufkommen zum Thema MRT fuer den Zeitraum 1981-2007 evaluiert und analysiert werden. Es wurde eine szientometrische Analyse (Datenbank: ISI-Web of Science, 1981-2007; Suchterm &apos

  13. Potential of electrical resistivity tomography and muon density imaging to study spatio-temporal variations in the sub-surface

    Lesparre, Nolwenn; Cabrera, Justo; Courbet, Christelle

    2015-04-01

    We explore the capacity of electrical resistivity tomography and muon density imaging to detect spatio-temporal variations of the medium surrounding a regional fault crossing the underground platform of Tournemire (Aveyron, France). The studied Cernon fault is sub-vertical and intersects perpendicularly the tunnel of Tournemire and extends to surface. The fault separates clay and limestones layers of the Dogger from limestones layers of the Lias. The Cernon fault presents a thickness of a ten of meters and drives water from an aquifer circulating at the top of the Dogger clay layer to the tunnel. An experiment combining electrical resistivity imaging and muon density imaging was setup taking advantage of the tunnel presence. A specific array of electrodes were set up, adapted for the characterization of the fault. Electrodes were placed along the tunnel as well as at the surface above the tunnel on both sides of the fault in order to acquire data in transmission across the massif to better cover the sounded medium. Electrical resistivity is particularly sensitive to water presence in the medium and thus carry information on the main water flow paths and on the pore space saturation. At the same time a muon sensor was placed in the tunnel under the fault region to detect muons coming from the sky after their crossing of the rock medium. Since the muon flux is attenuated as function of the quantity of matter crossed, muons flux measurements supply information on the medium average density along muons paths. The sensor presents 961 angles of view so measurements performed from one station allows a comparison of the muon flux temporal variations along the fault as well as in the medium surrounding the fault. As the water saturation of the porous medium fluctuates through time the medium density might indeed present sensible variations as shown by gravimetric studies. During the experiment important rainfalls occurred leading variations of the medium properties

  14. Microcirculatory Imaging in Cardiac Anesthesia: Ketanserin Reduces Blood Pressure But Not Perfused Capillary Density

    Elbers, Paul W. G.; Ozdemir, Alaattin; van Iterson, Mat; van Dongen, Eric P. A.; Ince, Can

    2009-01-01

    Objectives: It has become possible to image the human microcirculation at the bedside using sidestream dark field (SDF) imaging. This may help the clinician when correlation between global and microvascular hemodynamics may not be straightforward. Ketanserin, a serotonin and alpha-1 adrenoceptor

  15. Full field image reconstruction is suitable for high-pitch dual-source computed tomography.

    Mahnken, Andreas H; Allmendinger, Thomas; Sedlmair, Martin; Tamm, Miriam; Reinartz, Sebastian D; Flohr, Thomas

    2012-11-01

    The field of view (FOV) in high-pitch dual-source computed tomography (DSCT) is limited by the size of the second detector. The goal of this study was to develop and evaluate a full FOV image reconstruction technique for high-pitch DSCT. For reconstruction beyond the FOV of the second detector, raw data of the second system were extended to the full dimensions of the first system, using the partly existing data of the first system in combination with a very smooth transition weight function. During the weighted filtered backprojection, the data of the second system were applied with an additional weighting factor. This method was tested for different pitch values from 1.5 to 3.5 on a simulated phantom and on 25 high-pitch DSCT data sets acquired at pitch values of 1.6, 2.0, 2.5, 2.8, and 3.0. Images were reconstructed with FOV sizes of 260 × 260 and 500 × 500 mm. Image quality was assessed by 2 radiologists using a 5-point Likert scale and analyzed with repeated-measure analysis of variance. In phantom and patient data, full FOV image quality depended on pitch. Where complete projection data from both tube-detector systems were available, image quality was unaffected by pitch changes. Full FOV image quality was not compromised at pitch values of 1.6 and remained fully diagnostic up to a pitch of 2.0. At higher pitch values, there was an increasing difference in image quality between limited and full FOV images (P = 0.0097). With this new image reconstruction technique, full FOV image reconstruction can be used up to a pitch of 2.0.

  16. Evaluation of biodistribution and imaging of atherosclerotic lesions using 111In-labeled low-density lipoprotein

    Yamashina, Hisayo

    1993-01-01

    111 In-labeled low-density lipoprotein (LDL) was administered to Watanabe heritable hyperlipidemic rabbits (WHHL group) and control rabbits (control group) to evaluate its biodistribution and scintigraphic images by γ-camera and radioactivity of each organ. With external imaging, the heart, liver, kidney, bone and spleen of each rabbit were observed. By setting the region of interest, the liver/heart ratio of the WHHL group was significantly lower than that of the control group (p 111 In-labeled-LDL was recognized in the aortic arch, bifurcation of intercostal and celiac artery in the WHHL group. By the use of labeled LDL with the combination of γ-camera, it is capable of detecting the regulation of lipoprotein metabolism and imaging atherosclerotic lesions externally. (author)

  17. Open source software in a practical approach for post processing of radiologic images.

    Valeri, Gianluca; Mazza, Francesco Antonino; Maggi, Stefania; Aramini, Daniele; La Riccia, Luigi; Mazzoni, Giovanni; Giovagnoni, Andrea

    2015-03-01

    The purpose of this paper is to evaluate the use of open source software (OSS) to process DICOM images. We selected 23 programs for Windows and 20 programs for Mac from 150 possible OSS programs including DICOM viewers and various tools (converters, DICOM header editors, etc.). The programs selected all meet the basic requirements such as free availability, stand-alone application, presence of graphical user interface, ease of installation and advanced features beyond simple display monitor. Capabilities of data import, data export, metadata, 2D viewer, 3D viewer, support platform and usability of each selected program were evaluated on a scale ranging from 1 to 10 points. Twelve programs received a score higher than or equal to eight. Among them, five obtained a score of 9: 3D Slicer, MedINRIA, MITK 3M3, VolView, VR Render; while OsiriX received 10. OsiriX appears to be the only program able to perform all the operations taken into consideration, similar to a workstation equipped with proprietary software, allowing the analysis and interpretation of images in a simple and intuitive way. OsiriX is a DICOM PACS workstation for medical imaging and software for image processing for medical research, functional imaging, 3D imaging, confocal microscopy and molecular imaging. This application is also a good tool for teaching activities because it facilitates the attainment of learning objectives among students and other specialists.

  18. Simultaneous optical coherence tomography and lipofuscin autofluorescence imaging of the retina with a single broadband light source at 480nm

    Jiang, Minshan; Liu, Tan; Liu, Xiaojing; Jiao, Shuliang

    2014-01-01

    We accomplished spectral domain optical coherence tomography and auto-fluorescence microscopy for imaging the retina with a single broadband light source centered at 480 nm. This technique is able to provide simultaneous structural imaging and lipofuscin molecular contrast of the retina. Since the two imaging modalities are provided by the same group of photons, their images are intrinsically registered. To test the capabilities of the technique we periodically imaged the retinas of the same ...

  19. PyLDM - An open source package for lifetime density analysis of time-resolved spectroscopic data.

    Gabriel F Dorlhiac

    2017-05-01

    Full Text Available Ultrafast spectroscopy offers temporal resolution for probing processes in the femto- and picosecond regimes. This has allowed for investigation of energy and charge transfer in numerous photoactive compounds and complexes. However, analysis of the resultant data can be complicated, particularly in more complex biological systems, such as photosystems. Historically, the dual approach of global analysis and target modelling has been used to elucidate kinetic descriptions of the system, and the identity of transient species respectively. With regards to the former, the technique of lifetime density analysis (LDA offers an appealing alternative. While global analysis approximates the data to the sum of a small number of exponential decays, typically on the order of 2-4, LDA uses a semi-continuous distribution of 100 lifetimes. This allows for the elucidation of lifetime distributions, which may be expected from investigation of complex systems with many chromophores, as opposed to averages. Furthermore, the inherent assumption of linear combinations of decays in global analysis means the technique is unable to describe dynamic motion, a process which is resolvable with LDA. The technique was introduced to the field of photosynthesis over a decade ago by the Holzwarth group. The analysis has been demonstrated to be an important tool to evaluate complex dynamics such as photosynthetic energy transfer, and complements traditional global and target analysis techniques. Although theory has been well described, no open source code has so far been available to perform lifetime density analysis. Therefore, we introduce a python (2.7 based package, PyLDM, to address this need. We furthermore provide a direct comparison of the capabilities of LDA with those of the more familiar global analysis, as well as providing a number of statistical techniques for dealing with the regularization of noisy data.

  20. A scanning point source for quality control of FOV uniformity in GC-PET imaging

    Bergmann, H.; Minear, G.; Dobrozemsky, G.; Nowotny, R.; Koenig, B.

    2002-01-01

    Aim: PET imaging with coincidence cameras (GC-PET) requires additional quality control procedures to check the function of coincidence circuitry and detector zoning. In particular, the uniformity response over the field of view needs special attention since it is known that coincidence counting mode may suffer from non-uniformity effects not present in single photon mode. Materials and methods: An inexpensive linear scanner with a stepper motor and a digital interface to a PC with software allowing versatile scanning modes was developed. The scanner is used with a source holder containing a Sodium-22 point source. While moving the source along the axis of rotation of the GC-PET system, a tomographic acquisition takes place. The scan covers the full axial field of view of the 2-D or 3-D scatter frame. Depending on the acquisition software, point source scanning takes place continuously while only one projection is acquired or is done in step-and-shoot mode with the number of positions equal to the number of gantry steps. Special software was developed to analyse the resulting list mode acquisition files and to produce an image of the recorded coincidence events of each head. Results: Uniformity images of coincidence events were obtained after further correction for systematic sensitivity variations caused by acquisition geometry. The resulting images are analysed visually and by calculating NEMA uniformity indices as for a planar flood field. The method has been applied successfully to two different brands of GC-PET capable gamma cameras. Conclusion: Uniformity of GC-PET can be tested quickly and accurately with a routine QC procedure, using a Sodium-22 scanning point source and an inexpensive mechanical scanning device. The method can be used for both 2-D and 3-D acquisition modes and fills an important gap in the quality control system for GC-PET

  1. dcmqi: An Open Source Library for Standardized Communication of Quantitative Image Analysis Results Using DICOM.

    Herz, Christian; Fillion-Robin, Jean-Christophe; Onken, Michael; Riesmeier, Jörg; Lasso, Andras; Pinter, Csaba; Fichtinger, Gabor; Pieper, Steve; Clunie, David; Kikinis, Ron; Fedorov, Andriy

    2017-11-01

    Quantitative analysis of clinical image data is an active area of research that holds promise for precision medicine, early assessment of treatment response, and objective characterization of the disease. Interoperability, data sharing, and the ability to mine the resulting data are of increasing importance, given the explosive growth in the number of quantitative analysis methods being proposed. The Digital Imaging and Communications in Medicine (DICOM) standard is widely adopted for image and metadata in radiology. dcmqi (DICOM for Quantitative Imaging) is a free, open source library that implements conversion of the data stored in commonly used research formats into the standard DICOM representation. dcmqi source code is distributed under BSD-style license. It is freely available as a precompiled binary package for every major operating system, as a Docker image, and as an extension to 3D Slicer. Installation and usage instructions are provided in the GitHub repository at https://github.com/qiicr/dcmqi Cancer Res; 77(21); e87-90. ©2017 AACR . ©2017 American Association for Cancer Research.

  2. Imaging phase holdup distribution of three phase flow systems using dual source gamma ray tomography

    Varma, Rajneesh; Al-Dahhan, Muthanna; O'Sullivan, Joseph

    2008-01-01

    Full text: Multiphase reaction and process systems are used in abundance in the chemical and biochemical industry. Tomography has been successfully employed to visualize the hydrodynamics of multiphase systems. Most of the tomography methods (gamma ray, x-ray and electrical capacitance and resistance) have been successfully implemented for two phase dynamic systems. However, a significant number of chemical and biochemical systems consists of dynamic three phases. Research effort directed towards the development of tomography techniques to image such dynamic system has met with partial successes for specific systems with applicability to limited operating conditions. A dual source tomography scanner has been developed that uses the 661 keV and 1332 keV photo peaks from the 137 Cs and 60 Co for imaging three phase systems. A new approach has been developed and applied that uses the polyenergetic Alternating Minimization (A-M) algorithm, developed by O'Sullivan and Benac (2007), for imaging the holdup distribution in three phases' dynamic systems. The new approach avoids the traditional post image processing approach used to determine the holdup distribution where the attenuation images of the mixed flow obtained from gamma ray photons of two different energies are used to determine the holdup of three phases. In this approach the holdup images are directly reconstructed from the gamma ray transmission data. The dual source gamma ray tomography scanner and the algorithm were validated using a three phase phantom. Based in the validation, three phase holdup studies we carried out in slurry bubble column containing gas liquid and solid phases in a dynamic state using the dual energy gamma ray tomography. The key results of the holdup distribution studies in the slurry bubble column along with the validation of the dual source gamma ray tomography system would be presented and discussed

  3. Assessment of the sources of error affecting the quantitative accuracy of SPECT imaging in small animals

    Joint Graduate Group in Bioengineering, University of California, San Francisco and University of California, Berkeley; Department of Radiology, University of California; Gullberg, Grant T; Hwang, Andrew B.; Franc, Benjamin L.; Gullberg, Grant T.; Hasegawa, Bruce H.

    2008-02-15

    Small animal SPECT imaging systems have multiple potential applications in biomedical research. Whereas SPECT data are commonly interpreted qualitatively in a clinical setting, the ability to accurately quantify measurements will increase the utility of the SPECT data for laboratory measurements involving small animals. In this work, we assess the effect of photon attenuation, scatter and partial volume errors on the quantitative accuracy of small animal SPECT measurements, first with Monte Carlo simulation and then confirmed with experimental measurements. The simulations modeled the imaging geometry of a commercially available small animal SPECT system. We simulated the imaging of a radioactive source within a cylinder of water, and reconstructed the projection data using iterative reconstruction algorithms. The size of the source and the size of the surrounding cylinder were varied to evaluate the effects of photon attenuation and scatter on quantitative accuracy. We found that photon attenuation can reduce the measured concentration of radioactivity in a volume of interest in the center of a rat-sized cylinder of water by up to 50percent when imaging with iodine-125, and up to 25percent when imaging with technetium-99m. When imaging with iodine-125, the scatter-to-primary ratio can reach up to approximately 30percent, and can cause overestimation of the radioactivity concentration when reconstructing data with attenuation correction. We varied the size of the source to evaluate partial volume errors, which we found to be a strong function of the size of the volume of interest and the spatial resolution. These errors can result in large (>50percent) changes in the measured amount of radioactivity. The simulation results were compared with and found to agree with experimental measurements. The inclusion of attenuation correction in the reconstruction algorithm improved quantitative accuracy. We also found that an improvement of the spatial resolution through the

  4. Terahertz near-field imaging using subwavelength plasmonic apertures and a quantum cascade laser source.

    Baragwanath, Adam J; Freeman, Joshua R; Gallant, Andrew J; Zeitler, J Axel; Beere, Harvey E; Ritchie, David A; Chamberlain, J Martyn

    2011-07-01

    The first demonstration, to our knowledge, of near-field imaging using subwavelength plasmonic apertures with a terahertz quantum cascade laser source is presented. "Bull's-eye" apertures, featuring subwavelength circular apertures flanked by periodic annular corrugations were created using a novel fabrication method. A fivefold increase in intensity was observed for plasmonic apertures over plain apertures of the same diameter. Detailed studies of the transmitted beam profiles were undertaken for apertures with both planarized and corrugated exit facets, with the former producing spatially uniform intensity profiles and subwavelength spatial resolution. Finally, a proof-of-concept imaging experiment is presented, where an inhomogeneous pharmaceutical drug coating is investigated.

  5. Monte Carlo modeling of neutron imaging at the SINQ spallation source

    Lebenhaft, J.R.; Lehmann, E.H.; Pitcher, E.J.; McKinney, G.W.

    2003-01-01

    Modeling of the Swiss Spallation Neutron Source (SINQ) has been used to demonstrate the neutron radiography capability of the newly released MPI-version of the MCNPX Monte Carlo code. A detailed MCNPX model was developed of SINQ and its associated neutron transmission radiography (NEUTRA) facility. Preliminary validation of the model was performed by comparing the calculated and measured neutron fluxes in the NEUTRA beam line, and a simulated radiography image was generated for a sample consisting of steel tubes containing different materials. This paper describes the SINQ facility, provides details of the MCNPX model, and presents preliminary results of the neutron imaging. (authors)

  6. An open-source solution for advanced imaging flow cytometry data analysis using machine learning.

    Hennig, Holger; Rees, Paul; Blasi, Thomas; Kamentsky, Lee; Hung, Jane; Dao, David; Carpenter, Anne E; Filby, Andrew

    2017-01-01

    Imaging flow cytometry (IFC) enables the high throughput collection of morphological and spatial information from hundreds of thousands of single cells. This high content, information rich image data can in theory resolve important biological differences among complex, often heterogeneous biological samples. However, data analysis is often performed in a highly manual and subjective manner using very limited image analysis techniques in combination with conventional flow cytometry gating strategies. This approach is not scalable to the hundreds of available image-based features per cell and thus makes use of only a fraction of the spatial and morphometric information. As a result, the quality, reproducibility and rigour of results are limited by the skill, experience and ingenuity of the data analyst. Here, we describe a pipeline using open-source software that leverages the rich information in digital imagery using machine learning algorithms. Compensated and corrected raw image files (.rif) data files from an imaging flow cytometer (the proprietary .cif file format) are imported into the open-source software CellProfiler, where an image processing pipeline identifies cells and subcellular compartments allowing hundreds of morphological features to be measured. This high-dimensional data can then be analysed using cutting-edge machine learning and clustering approaches using "user-friendly" platforms such as CellProfiler Analyst. Researchers can train an automated cell classifier to recognize different cell types, cell cycle phases, drug treatment/control conditions, etc., using supervised machine learning. This workflow should enable the scientific community to leverage the full analytical power of IFC-derived data sets. It will help to reveal otherwise unappreciated populations of cells based on features that may be hidden to the human eye that include subtle measured differences in label free detection channels such as bright-field and dark-field imagery

  7. Imaging of Scattered Wavefields in Passive and Controlled-source Seismology

    AlTheyab, Abdullah

    2015-12-01

    Seismic waves are used to study the Earth, exploit its hydrocarbon resources, and understand its hazards. Extracting information from seismic waves about the Earth’s subsurface, however, is becoming more challenging as our questions become more complex and our demands for higher resolution increase. This dissertation introduces two new methods that use scattered waves for improving the resolution of subsurface images: natural migration of passive seismic data and convergent full-waveform inversion. In the first part of this dissertation, I describe a method where the recorded seismic data are used to image subsurface heterogeneities like fault planes. This method, denoted as natural migration of backscattered surface waves, provides higher resolution images for near-surface faults that is complementary to surface-wave tomography images. Our proposed method differ from contemporary methods in that it does not (1) require a velocity model of the earth, (2) assumes weak scattering, or (3) have a high computational cost. This method is applied to ambient noise recorded by the US-Array to map regional faults across the American continent. Natural migration can be formulated as a least-squares inversion to furtherer enhance the resolution and the quality of the fault images. This inversion is applied to ambient noise recorded in Long Beach, California to reveal a matrix of shallow subsurface faults. The second part of this dissertation describes a convergent full waveform inversion method for controlled source data. A controlled source excites waves that scatter from subsurface reflectors. The scattered waves are recorded by a large array of geophones. These recorded waves can be inverted for a high-resolution image of the subsurface by FWI, which is typically convergent for transmitted arrivals but often does not converge for deep reflected events. I propose a preconditioning approach that extends the ability of FWI to image deep parts of the velocity model, which

  8. Column Number Density Expressions Through M = 0 and M = 1 Point Source Plumes Along Any Straight Path

    Woronowicz, Michael

    2017-01-01

    Providers of payloads carried aboard the International Space Station must conduct analyses to demonstrate that any planned gaseous venting events generate no more than a certain level of material that may interfere with optical measurements from other experiments or payloads located nearby. This requirement is expressed in terms of a maximum column number density (CND). Depending on the level of rarefaction, such venting may be characterized by effusion for low flow rates, or by a sonic distribution at higher levels. Since the relative locations of other sensitive payloads are often unknown because they may refer to future projects, this requirement becomes a search for the maximum CND along any path.In another application, certain astronomical observations make use of CND to estimate light attenuation from a distant star through gaseous plumes, such as the Fermi Bubbles emanating from the vicinity of the black hole at the center of our Milky Way galaxy, in order to infer the amount of material being expelled via those plumes.This paper presents analytical CND expressions developed for general straight paths based upon a free molecule point source model for steady effusive flow and for a distribution fitted to model flows from a sonic orifice. Among other things, in this Mach number range it is demonstrated that the maximum CND from a distant location occurs along the path parallel to the source plane that intersects the plume axis. For effusive flows this value is exactly twice the CND found along the ray originating from that point of intersection and extending to infinity along the plumes axis. For sonic plumes this ratio is reduced to about 43.

  9. A generalized model for optimal transport of images including dissipation and density modulation

    Maas, Jan; Rumpf, Martin; Schö nlieb, Carola; Simon, Stefan

    2015-01-01

    transport to strongly dissipative dynamics. For this model a robust and effective variational time discretization of geodesic paths is proposed. This requires to minimize a discrete path energy consisting of a sum of consecutive image matching functionals

  10. Time domain localization technique with sparsity constraint for imaging acoustic sources

    Padois, Thomas; Doutres, Olivier; Sgard, Franck; Berry, Alain

    2017-09-01

    This paper addresses source localization technique in time domain for broadband acoustic sources. The objective is to accurately and quickly detect the position and amplitude of noise sources in workplaces in order to propose adequate noise control options and prevent workers hearing loss or safety risk. First, the generalized cross correlation associated with a spherical microphone array is used to generate an initial noise source map. Then a linear inverse problem is defined to improve this initial map. Commonly, the linear inverse problem is solved with an l2 -regularization. In this study, two sparsity constraints are used to solve the inverse problem, the orthogonal matching pursuit and the truncated Newton interior-point method. Synthetic data are used to highlight the performances of the technique. High resolution imaging is achieved for various acoustic sources configurations. Moreover, the amplitudes of the acoustic sources are correctly estimated. A comparison of computation times shows that the technique is compatible with quasi real-time generation of noise source maps. Finally, the technique is tested with real data.

  11. Elliptical local vessel density: a fast and robust quality metric for retinal images

    Giancardo, L.; Abramoff, M.D.; Chaum, E.; Karnowski, T.P.; Meriaudeau, F.; Tobin, K.W.

    2008-01-01

    A great effort of the research community is geared towards the creation of an automatic screening system able to promptly detect diabetic retinopathy with the use of fundus cameras. In addition, there are some documented approaches for automatically judging the image quality. We propose a new set of features independent of field of view or resolution to describe the morphology of the patient's vessels. Our initial results suggest that these features can be used to estimate the image quality i...

  12. Analysis of monochromatic and quasi-monochromatic X-ray sources in imaging and therapy

    Westphal, Maximillian; Lim, Sara; Nahar, Sultana; Orban, Christopher; Pradhan, Anil

    2017-04-01

    We studied biomedical imaging and therapeutic applications of recently developed quasi-monochromatic and monochromatic X-ray sources. Using the Monte Carlo code GEANT4, we found that the quasi-monochromatic 65 keV Gaussian X-ray spectrum created by inverse Compton scattering with relatavistic electron beams were capable of producing better image contrast with less radiation compared to conventional 120 kV broadband CT scans. We also explored possible experimental detection of theoretically predicted K α resonance fluorescence in high-Z elements using the European Synchrotron Research Facility with a tungsten (Z = 74) target. In addition, we studied a newly developed quasi-monochromatic source generated by converting broadband X-rays to monochromatic K α and β X-rays with a zirconium target (Z = 40). We will further study how these K α and K β dominated spectra can be implemented in conjunction with nanoparticles for targeted therapy. Acknowledgement: Ohio Supercomputer Center, Columbus, OH.

  13. Installation of spectrally selective imaging system in RF negative ion source

    Ikeda, K.; Kisaki, M.; Nagaoka, K.; Nakano, H.; Osakabe, M.; Tsumori, K.; Kaneko, O.; Takeiri, Y.; Wünderlich, D.; Fantz, U.; Heinemann, B.; Geng, S.

    2016-01-01

    A spectrally selective imaging system has been installed in the RF negative ion source in the International Thermonuclear Experimental Reactor-relevant negative ion beam test facility ELISE (Extraction from a Large Ion Source Experiment) to investigate distribution of hydrogen Balmer-α emission (H α ) close to the production surface of hydrogen negative ion. We selected a GigE vision camera coupled with an optical band-path filter, which can be controlled remotely using high speed network connection. A distribution of H α emission near the bias plate has been clearly observed. The same time trend on H α intensities measured by the imaging diagnostic and the optical emission spectroscopy is confirmed

  14. Spectroscopy for identification of plasma sources for lithography and water window imaging

    O'Sullivan, Gerry; Dunne, Padraig; Liu, Luning; Lokasani, Ragava; Long, Elaine; O'Reilly, Fergal; Sheridan, Paul; Sokell, Emma; Wu, Tao; Higashiguchi, Takeshi; Li, Bowen; Ohashi, Hayato; Suzuki, Chihiro

    2015-01-01

    The identification of sources for applications that include nanolithography, surface patterning and high resolution imaging is the focus of a considerable activity in the extreme ultraviolet (EUV) or soft x-ray (SXR) spectral regions. We report on the result of a study of the spectra from laser produced plasmas of a number of medium and high Z metals undertaken in order to identify potential sources for use with available multilayer mirrors. The main focus was the study of unresolved transition arrays emitted from ions with 3d, 4d and 4f valence subshells that emit strongly in the water window (2.34-4.38 nm).and that could be used for biological imaging or cell tomography. (paper)

  15. Group Independent Component Analysis (gICA) and Current Source Density (CSD) in the study of EEG in ADHD adults.

    Ponomarev, Valery A; Mueller, Andreas; Candrian, Gian; Grin-Yatsenko, Vera A; Kropotov, Juri D

    2014-01-01

    To investigate the performance of the spectral analysis of resting EEG, Current Source Density (CSD) and group independent components (gIC) in diagnosing ADHD adults. Power spectra of resting EEG, CSD and gIC (19 channels, linked ears reference, eyes open/closed) from 96 ADHD and 376 healthy adults were compared between eyes open and eyes closed conditions, and between groups of subjects. Pattern of differences in gIC and CSD spectral power between conditions was approximately similar, whereas it was more widely spatially distributed for EEG. Size effect (Cohen's d) of differences in gIC and CSD spectral power between groups of subjects was considerably greater than in the case of EEG. Significant reduction of gIC and CSD spectral power depending on conditions was found in ADHD patients. Reducing power in a wide frequency range in the fronto-central areas is a common phenomenon regardless of whether the eyes were open or closed. Spectral power of local EEG activity isolated by gICA or CSD in the fronto-central areas may be a suitable marker for discrimination of ADHD and healthy adults. Spectral analysis of gIC and CSD provides better sensitivity to discriminate ADHD and healthy adults. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  16. Influence of energy density of different light sources on Knoop hardness of a dual-cured resin cement.

    Piva, Evandro; Correr-Sobrinho, Lourenço; Sinhoreti, Mario Alexandre Coelho; Consani, Simonides; Demarco, Flávio Fernando; Powers, John Michael

    2008-01-01

    The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs) were tested: tungsten halogen light (HAL), light-emitting diode (LED) and xenon plasma-arc (PAC) lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce). Three energy doses were used by modifying the irradiance (I) of each LCU and the irradiation time (T): 24 Jcm(-2) (I/2x2T), 24 Jcm(-2) (IxT) and 48 Jcm(-2) (Ix2T). Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus). Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10). Knoop hardness number (KHN) means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (alpha=5%). Application of 48 J.cm(-2) energy dose through the ceramic using LED (50.5+/-2.8) and HAL (50.9+/-3.7) produced significantly higher KHN means (p<0.05) than the control (44.7+/-3.8). LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.

  17. Reduction of plasma density in the Helicity Injected Torus with Steady Inductance experiment by using a helicon pre-ionization source

    Hossack, Aaron C.; Jarboe, Thomas R.; Victor, Brian S.; Firman, Taylor; Prager, James R.; Ziemba, Timothy; Wrobel, Jonathan S.

    2013-01-01

    A helicon based pre-ionization source has been developed and installed on the Helicity Injected Torus with Steady Inductance (HIT-SI) spheromak. The source initiates plasma breakdown by injecting impurity-free, unmagnetized plasma into the HIT-SI confinement volume. Typical helium spheromaks have electron density reduced from (2–3) × 10 19 m −3 to 1 × 10 19 m −3 . Deuterium spheromak formation is possible with density as low as 2 × 10 18 m −3 . The source also enables HIT-SI to be operated with only one helicity injector at injector frequencies above 14.5 kHz. A theory explaining the physical mechanism driving the reduction of breakdown density is presented

  18. Reduction of plasma density in the Helicity Injected Torus with Steady Inductance experiment by using a helicon pre-ionization source

    Hossack, Aaron C.; Jarboe, Thomas R.; Victor, Brian S. [Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States); Firman, Taylor; Prager, James R.; Ziemba, Timothy [Eagle Harbor Technologies, Inc., 119 W. Denny Way, Suite 210, Seattle, Washington 98119 (United States); Wrobel, Jonathan S. [979B West Moorhead Circle, Boulder, Colorado 80305 (United States)

    2013-10-15

    A helicon based pre-ionization source has been developed and installed on the Helicity Injected Torus with Steady Inductance (HIT-SI) spheromak. The source initiates plasma breakdown by injecting impurity-free, unmagnetized plasma into the HIT-SI confinement volume. Typical helium spheromaks have electron density reduced from (2–3) × 10{sup 19} m{sup −3} to 1 × 10{sup 19} m{sup −3}. Deuterium spheromak formation is possible with density as low as 2 × 10{sup 18} m{sup −3}. The source also enables HIT-SI to be operated with only one helicity injector at injector frequencies above 14.5 kHz. A theory explaining the physical mechanism driving the reduction of breakdown density is presented.

  19. Computed tomographic images using tube source of x rays: interior properties of the material

    Rao, Donepudi V.; Takeda, Tohoru; Itai, Yuji; Seltzer, S. M.; Hubbell, John H.; Zeniya, Tsutomu; Akatsuka, Takao; Cesareo, Roberto; Brunetti, Antonio; Gigante, Giovanni E.

    2002-01-01

    An image intensifier based computed tomography scanner and a tube source of x-rays are used to obtain the images of small objects, plastics, wood and soft materials in order to know the interior properties of the material. A new method is developed to estimate the degree of monochromacy, total solid angle, efficiency and geometrical effects of the measuring system and the way to produce monoenergetic radiation. The flux emitted by the x-ray tube is filtered using the appropriate filters at the chosen optimum energy and reasonable monochromacy is achieved and the images are acceptably distinct. Much attention has been focused on the imaging of small objects of weakly attenuating materials at optimum value. At optimum value it is possible to calculate the three-dimensional representation of inner and outer surfaces of the object. The image contrast between soft materials could be significantly enhanced by optimal selection of the energy of the x-rays by Monte Carlo methods. The imaging system is compact, reasonably economic, has a good contrast resolution, simple operation and routine availability and explores the use of optimizing tomography for various applications.

  20. Dual-source computed tomography in patients with acute chest pain: feasibility and image quality

    Schertler, Thomas; Scheffel, Hans; Frauenfelder, Thomas; Desbiolles, Lotus; Leschka, Sebastian; Stolzmann, Paul; Marincek, Borut; Alkadhi, Hatem [University Hospital Zurich, Department of Medical Radiology, Institute of Diagnostic Radiology, Zurich (Switzerland); Seifert, Burkhardt [University of Zurich, Department of Biostatistics, Zurich (Switzerland); Flohr, Thomas G. [Computed Tomography CTE PA, Siemens Medical Solutions, Forchheim (Germany)

    2007-12-15

    The aim of this study was to determine the feasibility and image quality of dual-source computed tomography angiography (DSCTA) in patients with acute chest pain for the assessment of the lung, thoracic aorta, and for pulmonary and coronary arteries. Sixty consecutive patients (32 female, 28 male, mean age 58.1{+-}16.3 years) with acute chest pain underwent contrast-enhanced electrocardiography-gated DSCTA without prior beta-blocker administration. Vessel attenuation of different thoracic vascular territories was measured, and image quality was semi-quantitatively analyzed by two independent readers. Image quality of the thoracic aorta was diagnostic in all 60 patients, image quality of pulmonary arteries was diagnostic in 59, and image quality of coronary arteries was diagnostic in 58 patients. Pairwise intraindividual comparisons of attenuation values were small and ranged between 1{+-}6 HU comparing right and left coronary artery and 56{+-}9 HU comparing the pulmonary trunk and left ventricle. Mean attenuation was 291{+-}65 HU in the ascending aorta, 334{+-}93 HU in the pulmonary trunk, and 285{+-}66 HU and 268{+-}67 HU in the right and left coronary artery, respectively. DSCTA is feasible and provides diagnostic image quality of the thoracic aorta, pulmonary and coronary arteries in patients with acute chest pain. (orig.)

  1. Scaled nonuniform Fourier transform for image reconstruction in swept source optical coherence tomography

    Mezgebo, Biniyam; Nagib, Karim; Fernando, Namal; Kordi, Behzad; Sherif, Sherif

    2018-02-01

    Swept Source optical coherence tomography (SS-OCT) is an important imaging modality for both medical and industrial diagnostic applications. A cross-sectional SS-OCT image is obtained by applying an inverse discrete Fourier transform (DFT) to axial interferograms measured in the frequency domain (k-space). This inverse DFT is typically implemented as a fast Fourier transform (FFT) that requires the data samples to be equidistant in k-space. As the frequency of light produced by a typical wavelength-swept laser is nonlinear in time, the recorded interferogram samples will not be uniformly spaced in k-space. Many image reconstruction methods have been proposed to overcome this problem. Most such methods rely on oversampling the measured interferogram then use either hardware, e.g., Mach-Zhender interferometer as a frequency clock module, or software, e.g., interpolation in k-space, to obtain equally spaced samples that are suitable for the FFT. To overcome the problem of nonuniform sampling in k-space without any need for interferogram oversampling, an earlier method demonstrated the use of the nonuniform discrete Fourier transform (NDFT) for image reconstruction in SS-OCT. In this paper, we present a more accurate method for SS-OCT image reconstruction from nonuniform samples in k-space using a scaled nonuniform Fourier transform. The result is demonstrated using SS-OCT images of Axolotl salamander eggs.

  2. Conception and data transfer analysis of an open-source digital image archive designed for radiology

    Teichgraeber, U.K.M.; Lehmkuhl, L.; Harderer, A.; Emmel, D.; Ehrenstein, T.; Ricke, J.; Felix, R.

    2003-01-01

    Purpose: Implementation of a self-designed, web-based digital image archive incorporating the existing DICOM infrastructure to assure distribution of digital pictures and reports and to optimize work flow. Assessment after three years. Materials and methods: Open-source software was used to guarantee highest reliability and cost effectiveness. In view of rapidly increasing capacity and decreasing costs of hard discs (HDs), HDs were preferred over slower and expensive magneto-optical disk (MOD) or tape storage systems. The number of installed servers increased from one to 12. By installing HDs with increased capacities, the number of servers should be kept constant. Entry and access of data were analyzed over two 4-month periods (after 1.5 and 2 years of continuous operations). Results: Our digital image archive was found to be very reliable, cost effective and suitable for its designated tasks. As judged from the measured access volume, the average utilization of the system increased by 160%. In the period from January to April 2002, the users accessed 239.8 gigabyte of the stored 873.7 gigabyte image data (27%). The volume of the stored data added 20%, mainly due to an increase in cross-section imaging. Conclusion: The challenge of developing a digital image archive with limited financial resources resulted in a practicable and expandable solution. The utilization, number of active users and volume of transferred data have increased significantly. Our concept of utilizing HDs for image storage proved to be successful. (orig.) [de

  3. Preliminary study of single contrast enhanced dual energy heart imaging using dual-source CT

    Peng Jin; Zhang Longjiang; Zhou Changsheng; Lu Guangming; Ma Yan; Gu Haifeng

    2009-01-01

    Objective: To evaluate the feasibility and preliminary applications of single contrast enhanced dual energy heart imaging using dual-source CT (DSCT). Methods: Thirty patients underwent dual energy heart imaging with DSCT, of which 6 cases underwent SPECT or DSA within one week. Two experienced radiologists assessed image quality of coronary arteries and iodine map of myocardium. and correlated the coronary artery stenosis with the perfusion distribution of iodine map. Results: l00% (300/300) segments reached diagnostic standards. The mean score of image for all patients was 4.68±0.57. Mural coronary artery was present in 10 segments in S cases, atherosclerotic plaques in 32 segments in 12 cases, of which 20 segments having ≥50% stenosis, 12 segments ≤50% stenosis; dual energy CT coronary angiography was consistent with the DSA in 3 patients. 37 segmental perfusion abnormalities on iodine map were found in 15 cases, including 28 coronary blood supply segment narrow segment and 9 no coronary stenosis (including three negative segments in SPECD. Conclusion: Single contrast enhanced dual energy heart imaging can provide good coronary artery and myocardium perfusion images in the patients with appropriate heart rate, which has a potential to be used in the clinic and further studies are needed. (authors)

  4. SIproc: an open-source biomedical data processing platform for large hyperspectral images.

    Berisha, Sebastian; Chang, Shengyuan; Saki, Sam; Daeinejad, Davar; He, Ziqi; Mankar, Rupali; Mayerich, David

    2017-04-10

    There has recently been significant interest within the vibrational spectroscopy community to apply quantitative spectroscopic imaging techniques to histology and clinical diagnosis. However, many of the proposed methods require collecting spectroscopic images that have a similar region size and resolution to the corresponding histological images. Since spectroscopic images contain significantly more spectral samples than traditional histology, the resulting data sets can approach hundreds of gigabytes to terabytes in size. This makes them difficult to store and process, and the tools available to researchers for handling large spectroscopic data sets are limited. Fundamental mathematical tools, such as MATLAB, Octave, and SciPy, are extremely powerful but require that the data be stored in fast memory. This memory limitation becomes impractical for even modestly sized histological images, which can be hundreds of gigabytes in size. In this paper, we propose an open-source toolkit designed to perform out-of-core processing of hyperspectral images. By taking advantage of graphical processing unit (GPU) computing combined with adaptive data streaming, our software alleviates common workstation memory limitations while achieving better performance than existing applications.

  5. Dual-source computed tomography in patients with acute chest pain: feasibility and image quality

    Schertler, Thomas; Scheffel, Hans; Frauenfelder, Thomas; Desbiolles, Lotus; Leschka, Sebastian; Stolzmann, Paul; Marincek, Borut; Alkadhi, Hatem; Seifert, Burkhardt; Flohr, Thomas G.

    2007-01-01

    The aim of this study was to determine the feasibility and image quality of dual-source computed tomography angiography (DSCTA) in patients with acute chest pain for the assessment of the lung, thoracic aorta, and for pulmonary and coronary arteries. Sixty consecutive patients (32 female, 28 male, mean age 58.1±16.3 years) with acute chest pain underwent contrast-enhanced electrocardiography-gated DSCTA without prior beta-blocker administration. Vessel attenuation of different thoracic vascular territories was measured, and image quality was semi-quantitatively analyzed by two independent readers. Image quality of the thoracic aorta was diagnostic in all 60 patients, image quality of pulmonary arteries was diagnostic in 59, and image quality of coronary arteries was diagnostic in 58 patients. Pairwise intraindividual comparisons of attenuation values were small and ranged between 1±6 HU comparing right and left coronary artery and 56±9 HU comparing the pulmonary trunk and left ventricle. Mean attenuation was 291±65 HU in the ascending aorta, 334±93 HU in the pulmonary trunk, and 285±66 HU and 268±67 HU in the right and left coronary artery, respectively. DSCTA is feasible and provides diagnostic image quality of the thoracic aorta, pulmonary and coronary arteries in patients with acute chest pain. (orig.)

  6. Accuracy of Dual-Energy Virtual Monochromatic CT Numbers: Comparison between the Single-Source Projection-Based and Dual-Source Image-Based Methods.

    Ueguchi, Takashi; Ogihara, Ryota; Yamada, Sachiko

    2018-03-21

    To investigate the accuracy of dual-energy virtual monochromatic computed tomography (CT) numbers obtained by two typical hardware and software implementations: the single-source projection-based method and the dual-source image-based method. A phantom with different tissue equivalent inserts was scanned with both single-source and dual-source scanners. A fast kVp-switching feature was used on the single-source scanner, whereas a tin filter was used on the dual-source scanner. Virtual monochromatic CT images of the phantom at energy levels of 60, 100, and 140 keV were obtained by both projection-based (on the single-source scanner) and image-based (on the dual-source scanner) methods. The accuracy of virtual monochromatic CT numbers for all inserts was assessed by comparing measured values to their corresponding true values. Linear regression analysis was performed to evaluate the dependency of measured CT numbers on tissue attenuation, method, and their interaction. Root mean square values of systematic error over all inserts at 60, 100, and 140 keV were approximately 53, 21, and 29 Hounsfield unit (HU) with the single-source projection-based method, and 46, 7, and 6 HU with the dual-source image-based method, respectively. Linear regression analysis revealed that the interaction between the attenuation and the method had a statistically significant effect on the measured CT numbers at 100 and 140 keV. There were attenuation-, method-, and energy level-dependent systematic errors in the measured virtual monochromatic CT numbers. CT number reproducibility was comparable between the two scanners, and CT numbers had better accuracy with the dual-source image-based method at 100 and 140 keV. Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  7. Coronary artery anomalies in adults: imaging at dual source CT coronary angiography

    Laspas, Fotios; Roussakis, Arkadios; Mourmouris, Christos; Kritikos, Nikolaos; Efthimiadou, Roxani; Andreou, John

    2013-01-01

    Congenital abnormalities of the coronary arteries have an incidence of 1%, and most of these are benign. However, a small number are associated with myocardial ischaemia and sudden death. Various imaging modalities are available for coronary artery assessment. Recently, multi-detector CT has emerged as an accurate diagnostic tool for defining coronary artery anomalies. The purpose of this pictorial essay is to review the dual source CT appearance of congenital anomalies of the coronary arteries in adults.

  8. Auralisations with loudspeaker arrays from a phased combination of the image source method and acoustical radiosity

    Marbjerg, Gerd Høy

    2017-01-01

    In order to create a simulation tool that is well-suited for small rooms with low diffusion and highly absorbing ceilings, a new room acoustic simulation tool has been developed that combines a phased version of the image source with acoustical radiosity and that considers the angle dependence...... impulse response, because more directional information is available with acoustical radiosity. Small rooms with absorbing surfaces are tested, because this is the room type that PARISM is particularly useful for....

  9. Auralizations with loudspeaker arrays from a phased combination of the image source method and acoustical radiosity

    Marbjerg, Gerd Høy; Brunskog, Jonas; Jeong, Cheol-Ho

    2017-01-01

    In order to create a simulation tool that is well-suited for small rooms with low diffusion and highly absorbing ceilings, a new room acoustic simulation tool has been developed that combines a phased version of the image source with acoustical radiosity and that considers the angle dependence...... of the PARISM impulse response, because more directional information is available with acoustical radiosity. Small rooms with absorbing surfaces are tested, because this is the room type that PARISM is particularly useful for....

  10. Quantifying protein densities on cell membranes using super-resolution optical fluctuation imaging

    Lukeš, T.; Glatzová, Daniela; Kvíčalová, Zuzana; Levet, F.; Benda, Aleš; Letschert, S.; Sauer, M.; Brdička, Tomáš; Lasser, T.; Cebecauer, Marek

    2017-01-01

    Roč. 8, č. 1 (2017), č. článku 1731. ISSN 2041-1723 R&D Projects: GA ČR GA15-06989S Institutional support: RVO:61388955 ; RVO:68378050 Keywords : quantifying protein densities * membranes * single-molecule localization microscopy Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 12.124, year: 2016

  11. Gold nanocrystal labeling allows low-density lipoprotein imaging from the subcellular to macroscopic level

    Allijn, Iris E.; Leong, Wei; Tang, Jun; Gianella, Anita; Mieszawska, Aneta J.; Fay, Francois; Ma, Ge; Russell, Stewart; Callo, Catherine B.; Gordon, Ronald E.; Korkmaz, Emine; Post, Jan Andries; Zhao, Yiming; Gerritsen, Hans C.; Thran, Axel; Proksa, Roland; Daerr, Heiner; Storm, Gert; Fuster, Valentin; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J. M.; Cormode, David P.

    2013-01-01

    Low-density lipoprotein (LDL) plays a critical role in cholesterol transport and is closely linked to the progression of several diseases. This motivates the development of methods to study LDL behavior from the microscopic to whole-body level. We have developed an approach to efficiently load LDL

  12. Global imaging of the Earth's deep interior: seismic constraints on (an)isotropy, density and attenuation

    Trampert, J.; Fichtner, A.

    2013-01-01

    Seismic tomography is the principal tool to probe the deep interior of the Earth. Models of seismic anisotropy induced by crystal alignment provide insight into the underlying convective motion, and variations of density allow us to discriminate between thermal and compositional heterogeneities.

  13. SU-E-J-233: Effect of Brachytherapy Seed Artifacts in T2 and Proton Density Maps in MR Images

    Mashouf, S [Sunnybrook Odette Cancer Centre, Toronto, Ontario (Canada); University of Toronto, Dept of Radiation Oncology, Toronto, Ontario (Canada); Fatemi-Ardekani, A [Sunnybrook Odette Cancer Centre, Toronto, Ontario (Canada); Sunnybrook Research Institute, Toronto, Ontario (Canada); Song, W [Sunnybrook Odette Cancer Centre, Toronto, Ontario (Canada); University of Toronto, Dept of Radiation Oncology, Toronto, Ontario (Canada); Sunnybrook Research Institute, Toronto, Ontario (Canada)

    2015-06-15

    Purpose: This study aims at investigating the influence of brachytherapy seeds on T2 and proton density (PD) maps generated from MR images. Proton density maps can be used to extract water content. Since dose absorbed in tissue surrounding low energy brachytherapy seeds are highly influenced by tissue composition, knowing the water content is a first step towards implementing a heterogeneity correction algorithm using MR images. Methods: An LDR brachytherapy (IsoAid Advantage Pd-103) seed was placed in the middle of an agar-based gel phantom and imaged using a 3T Philips MR scanner with a 168-channel head coil. A multiple echo sequence with TE=20, 40, 60, 80, 100 (ms) with large repetition time (TR=6259ms) was used to extract T2 and PD maps. Results: Seed artifacts were considerably reduced on T2 maps compared to PD maps. The variation of PD around the mean was obtained as −97% to 125% (±1%) while for T2 it was recorded as −71% to 24% (±1%). Conclusion: PD maps which are required for heterogeneity corrections are susceptible to artifacts from seeds. Seed artifacts on T2 maps, however, are significantly reduced due to not being sensitive to B0 field variation.

  14. Accuracy limits for the determination of cortical width and density: the influence of object size and CT imaging parameters

    Prevrhal, S.; Engelke, K.; Kalender, W.A.

    1999-01-01

    In this study we analysed the accuracy of computed tomography (CT) measurements in assessing cortical bone. We determined the dependency of thickness and density measurements on the true width and density of the cortex and on the spatial resolution in the CT images using two optimized segmentation methods. As a secondary goal, we assessed the ability of CT to reflect small changes in cortical thickness. Two different bone-mimicking phantoms with varying cortical thickness were scanned with single-slice CT on a Somatom Plus 4 scanner. Images were reconstructed with both a standard and a high-resolution convolution kernel. Two special operator-independent segmentation methods were used to automatically detect the edges of the cortical shell. We measured cortical thickness and density and compared the phantom measurements with theoretical computations by simulating a cross-sectional shape of the cortical shell. Based on the simulations, we calculated CT's power to detect small changes in cortical thickness. Simulations and phantom measurements were in very good agreement. Cortical thickness could be measured with an error of less than 10% if the true thickness was larger than 0.9 (0.7) mm for the standard (high-resolution) kernel which is close to the full width at half maximum (FWHM) of the point spread functions for these kernels and our scanner. Density measurements yielded errors of less than 10% for true cortical thickness values above two to three times the FWHM corresponding to 2.5 (2) mm in our case. The simulations showed that a 10% change in cortical width would not be detected with satisfying probability in bones with a cortical shell thinner than 1.2 mm. An accurate determination of the cortical thickness is limited to bones with a thickness higher than the FWHM of the scanner's point spread function. Therefore, the use of a high-resolution reconstruction kernel is crucial. Cortical bone mineral density can only be measured accurately in bones two to three

  15. Association of age and macular pigment optical density using dual-wavelength autofluorescence imaging.

    Lima, Verônica Castro; Rosen, Richard B; Prata, Tiago Santos; Dorairaj, Syril; Spielberg, Leigh; Maia, Mauricio; Sallum, Juliana M

    2013-01-01

    Several lines of evidence suggest that macular pigment may play a protective role against age-related macular degeneration, but the influence of age on macular pigment density levels remains unclear. This study was designed to investigate the relationship between age and the normal distribution of macular pigment optical density (MPOD) values surrounding the fovea. Consecutive healthy subjects with no evidence of ocular disease were enrolled in this study. After inclusion, MPOD values were measured at specific eccentricities (0.5, 1, and 2 degrees) from the foveal center using a dual-wavelength autofluorescence method employing a modified confocal scanning laser ophthalmoscope. Whenever both eyes were eligible, one was randomly selected for analysis. The correlation between age and MPOD values was investigated using regression analysis. Thirty subjects (30 eyes) were included (mean age 48.6 ± 16.4 [range 23-77] years). Significant differences were found between MPOD values measured at 0.5, 1, and 2 degrees from the center of the fovea (0.49 ± 0.12 density units, 0.37 ± 0.11 density units, and 0.13 ± 0.05 density units, respectively, P < 0.05). Significant correlations between age and MPOD values at 0.5 and 1 degree were found (P ≤ 0.02). Values measured at 2 degrees did not correlate significantly with age (P = 0.06). In healthy subjects, MPOD values were highest near the foveal center. These values appeared to increase during adulthood (peak at 45-50 years), followed by a gradual reduction after 60 years of age.

  16. Fast X-ray imaging at beamline I13L at Diamond Light Source

    Fanis, A De; Pešić, Z D; Wagner, U; Rau, C

    2013-01-01

    The imaging branch of the dual-branch beamline I13L at Diamond Light Source has been operational since April 2012. This branch is dedicated to hard X-ray imaging (in-line phase contrast radiography and tomography, and full-field microscopy), with energies in the ranges 6-30keV. At present we aim to achieve spatial resolution of the order of 1 μm over a field of view of l-20mm 2 . This branch aims to excel at imaging experiment of fast dynamic processes, where it is of interest to have short exposure times and high frame rates. To accommodate for this, we prepared for the beamline to operate with 'pink' beam to provide higher flux, an efficient detection system, and rapid data acquisition, transfer, and saving to storage. This contributed paper describes the present situation and illustrate the author's goal for the mid-future.

  17. Fast X-ray imaging at beamline I13L at Diamond Light Source

    De Fanis, A.; Pešić, Z. D.; Wagner, U.; Rau, C.

    2013-03-01

    The imaging branch of the dual-branch beamline I13L at Diamond Light Source has been operational since April 2012. This branch is dedicated to hard X-ray imaging (in-line phase contrast radiography and tomography, and full-field microscopy), with energies in the ranges 6-30keV. At present we aim to achieve spatial resolution of the order of 1 μm over a field of view of l-20mm2. This branch aims to excel at imaging experiment of fast dynamic processes, where it is of interest to have short exposure times and high frame rates. To accommodate for this, we prepared for the beamline to operate with "pink" beam to provide higher flux, an efficient detection system, and rapid data acquisition, transfer, and saving to storage. This contributed paper describes the present situation and illustrate the author's goal for the mid-future.

  18. Remote defect imaging for plate-like structures based on the scanning laser source technique

    Hayashi, Takahiro; Maeda, Atsuya; Nakao, Shogo

    2018-04-01

    In defect imaging with a scanning laser source technique, the use of a fixed receiver realizes stable measurements of flexural waves generated by laser at multiple rastering points. This study discussed the defect imaging by remote measurements using a laser Doppler vibrometer as a receiver. Narrow-band burst waves were generated by modulating laser pulse trains of a fiber laser to enhance signal to noise ratio in frequency domain. Averaging three images obtained at three different frequencies suppressed spurious distributions due to resonance. The experimental system equipped with these newly-devised means enabled us to visualize defects and adhesive objects in plate-like structures such as a plate with complex geometries and a branch pipe.

  19. Low-Complexity Compression Algorithm for Hyperspectral Images Based on Distributed Source Coding

    Yongjian Nian

    2013-01-01

    Full Text Available A low-complexity compression algorithm for hyperspectral images based on distributed source coding (DSC is proposed in this paper. The proposed distributed compression algorithm can realize both lossless and lossy compression, which is implemented by performing scalar quantization strategy on the original hyperspectral images followed by distributed lossless compression. Multilinear regression model is introduced for distributed lossless compression in order to improve the quality of side information. Optimal quantized step is determined according to the restriction of the correct DSC decoding, which makes the proposed algorithm achieve near lossless compression. Moreover, an effective rate distortion algorithm is introduced for the proposed algorithm to achieve low bit rate. Experimental results show that the compression performance of the proposed algorithm is competitive with that of the state-of-the-art compression algorithms for hyperspectral images.

  20. Basic study on gamma- and X-ray imaging technology using miniature radiation source

    Saito, Naoki; Koroki, Kenro; Kurosawa, Kenji

    2000-01-01

    In order to visualize a concealed unlawful matter, visualization using X-ray perspective image is effective, which is actualized. However, it is insufficient by conventional X-ray perspective image to visualize matters and substances of light elements such as narcotics, plastic bombs, and so forth, especially those in a metal container. Then, this study aims at basic research on visualization of perspective image on a weapon such as pistol and so on or a light element substance in a metal container such as car by using gamma-ray with various wave-lengths from a small radiation source. In 1998 fiscal year, a photographing system consisting of an X-ray 2 and a cooled CCD camera was constructed to carry out some simple photographing experiments. By judging through this experimental results only, 57 Co can be said to be more suitable to gamma-ray source for the perspective image photographing than 137 Cs is, which will be a future subject because of supposed dependence of specimen amount, shielding panel thickness or detector. (G.K.)

  1. Interferometrically enhanced sub-terahertz picosecond imaging utilizing a miniature collapsing-field-domain source

    Vainshtein, Sergey N.; Duan, Guoyong; Mikhnev, Valeri A.; Zemlyakov, Valery E.; Egorkin, Vladimir I.; Kalyuzhnyy, Nikolay A.; Maleev, Nikolai A.; Näpänkangas, Juha; Sequeiros, Roberto Blanco; Kostamovaara, Juha T.

    2018-05-01

    Progress in terahertz spectroscopy and imaging is mostly associated with femtosecond laser-driven systems, while solid-state sources, mainly sub-millimetre integrated circuits, are still in an early development phase. As simple and cost-efficient an emitter as a Gunn oscillator could cause a breakthrough in the field, provided its frequency limitations could be overcome. Proposed here is an application of the recently discovered collapsing field domains effect that permits sub-THz oscillations in sub-micron semiconductor layers thanks to nanometer-scale powerfully ionizing domains arising due to negative differential mobility in extreme fields. This shifts the frequency limit by an order of magnitude relative to the conventional Gunn effect. Our first miniature picosecond pulsed sources cover the 100-200 GHz band and promise milliwatts up to ˜500 GHz. Thanks to the method of interferometrically enhanced time-domain imaging proposed here and the low single-shot jitter of ˜1 ps, our simple imaging system provides sufficient time-domain imaging contrast for fresh-tissue terahertz histology.

  2. Verification of source and collimator configuration for Gamma Knife Perfexion using panoramic imaging

    Cho, Young-Bin; Prooijen, Monique van; Jaffray, David A.; Islam, Mohammad K.

    2010-01-01

    Purpose: The new model of stereotactic radiosurgery system, Gamma Knife Perfexion, allows automatic selection of built-in collimation, eliminating the need for the time consuming manual collimator installation required with previous models. However, the configuration of sources and collimators inside the system does not permit easy access for the verification of the selected collimation. While the conventional method of exposing a film at the isocenter is useful for obtaining composite dose information, it is difficult to interpret the data in terms of the integrity of each individual source and corresponding collimation. The primary aim of this study was to develop a method of verifying the geometric configuration of the sources and collimator modules of the Gamma Knife Perfexion. In addition, the method was extended to make dose measurements and verify the accuracy of dose distributions calculated by the mathematical formalism used in the treatment planning system, Leksell Gamma Plan. Methods: A panoramic view of all of 192 cobalt sources was simultaneously acquired by exposing a radiochromic film wrapped around the surface of a cylindrical phantom. The center of the phantom was mounted at the isocenter with its axis aligned along the longitudinal axis of the couch. The sizes and shapes of the source images projected on the phantom surface were compared to those calculated based on the manufacturer's design specifications. The measured dose at various points on the film was also compared to calculations using the algorithm of the planning system. Results: The panoramic images allowed clear identification of each of the 192 sources, verifying source integrity and selected collimator sizes. Dose on the film surface is due to the primary beam as well as phantom scatter and leakage contributions. Therefore, the dose at a point away from the isocenter cannot be determined simply based on the proportionality of collimator output factors; the use of a dose computation

  3. Testing a high-power LED based light source for hyperspectral imaging microscopy

    Klomkaew, Phiwat; Mayes, Sam A.; Rich, Thomas C.; Leavesley, Silas J.

    2017-02-01

    Our lab has worked to develop high-speed hyperspectral imaging systems that scan the fluorescence excitation spectrum for biomedical imaging applications. Hyperspectral imaging can be used in remote sensing, medical imaging, reaction analysis, and other applications. Here, we describe the development of a hyperspectral imaging system that comprised an inverted Nikon Eclipse microscope, sCMOS camera, and a custom light source that utilized a series of high-power LEDs. LED selection was performed to achieve wavelengths of 350-590 nm. To reduce scattering, LEDs with low viewing angles were selected. LEDs were surface-mount soldered and powered by an RCD. We utilized 3D printed mounting brackets to assemble all circuit components. Spectraradiometric calibration was performed using a spectrometer (QE65000, Ocean Optics) and integrating sphere (FOIS-1, Ocean Optics). Optical output and LED driving current were measured over a range of illumination intensities. A normalization algorithm was used to calibrate and optimize the intensity of the light source. The highest illumination power was at 375 nm (3300 mW/cm2), while the lowest illumination power was at 515, 525, and 590 nm (5200 mW/cm2). Comparing the intensities supplied by each LED to the intensities measured at the microscope stage, we found there was a great loss in power output. Future work will focus on using two of the same LEDs to double the power and finding more LED and/or laser diodes and chips around the range. This custom hyperspectral imaging system could be used for the detection of cancer and the identification of biomolecules.

  4. Analyzer-based phase-contrast imaging system using a micro focus x-ray source

    Zhou, Wei; Majidi, Keivan; Brankov, Jovan G.

    2014-01-01

    Here we describe a new in-laboratory analyzer based phase contrast-imaging (ABI) instrument using a conventional X-ray tube source (CXS) aimed at bio-medical imaging applications. Phase contrast-imaging allows visualization of soft tissue details usually obscured in conventional X-ray imaging. The ABI system design and major features are described in detail. The key advantage of the presented system, over the few existing CXS ABI systems, is that it does not require high precision components, i.e., CXS, X-ray detector, and electro-mechanical components. To overcome a main problem introduced by these components, identified as temperature stability, the system components are kept at a constant temperature inside of three enclosures, thus minimizing the electrical and mechanical thermal drifts. This is achieved by using thermoelectric (Peltier) cooling/heating modules that are easy to control precisely. For CXS we utilized a microfocus X-ray source with tungsten (W) anode material. In addition the proposed system eliminates tungsten's multiple spectral lines by selecting monochromator crystal size appropriately therefore eliminating need for the costly mismatched, two-crystal monochromator. The system imaging was fine-tuned for tungsten Kα 1 line with the energy of 59.3 keV since it has been shown to be of great clinical significance by a number of researchers at synchrotron facilities. In this way a laboratory system that can be used for evaluating and quantifying tissue properties, initially explored at synchrotron facilities, would be of great interest to a larger research community. To demonstrate the imaging capability of our instrument we use a chicken thigh tissue sample

  5. Analyzer-based phase-contrast imaging system using a micro focus x-ray source

    Zhou, Wei; Majidi, Keivan; Brankov, Jovan G.

    2014-08-01

    Here we describe a new in-laboratory analyzer based phase contrast-imaging (ABI) instrument using a conventional X-ray tube source (CXS) aimed at bio-medical imaging applications. Phase contrast-imaging allows visualization of soft tissue details usually obscured in conventional X-ray imaging. The ABI system design and major features are described in detail. The key advantage of the presented system, over the few existing CXS ABI systems, is that it does not require high precision components, i.e., CXS, X-ray detector, and electro-mechanical components. To overcome a main problem introduced by these components, identified as temperature stability, the system components are kept at a constant temperature inside of three enclosures, thus minimizing the electrical and mechanical thermal drifts. This is achieved by using thermoelectric (Peltier) cooling/heating modules that are easy to control precisely. For CXS we utilized a microfocus X-ray source with tungsten (W) anode material. In addition the proposed system eliminates tungsten's multiple spectral lines by selecting monochromator crystal size appropriately therefore eliminating need for the costly mismatched, two-crystal monochromator. The system imaging was fine-tuned for tungsten Kα1 line with the energy of 59.3 keV since it has been shown to be of great clinical significance by a number of researchers at synchrotron facilities. In this way a laboratory system that can be used for evaluating and quantifying tissue properties, initially explored at synchrotron facilities, would be of great interest to a larger research community. To demonstrate the imaging capability of our instrument we use a chicken thigh tissue sample.

  6. Analyzer-based phase-contrast imaging system using a micro focus x-ray source

    Zhou, Wei [BME Department, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Majidi, Keivan; Brankov, Jovan G., E-mail: brankov@iit.edu [ECE Department, Illinois Institute of Technology, Chicago, Illinois 60616 (United States)

    2014-08-15

    Here we describe a new in-laboratory analyzer based phase contrast-imaging (ABI) instrument using a conventional X-ray tube source (CXS) aimed at bio-medical imaging applications. Phase contrast-imaging allows visualization of soft tissue details usually obscured in conventional X-ray imaging. The ABI system design and major features are described in detail. The key advantage of the presented system, over the few existing CXS ABI systems, is that it does not require high precision components, i.e., CXS, X-ray detector, and electro-mechanical components. To overcome a main problem introduced by these components, identified as temperature stability, the system components are kept at a constant temperature inside of three enclosures, thus minimizing the electrical and mechanical thermal drifts. This is achieved by using thermoelectric (Peltier) cooling/heating modules that are easy to control precisely. For CXS we utilized a microfocus X-ray source with tungsten (W) anode material. In addition the proposed system eliminates tungsten's multiple spectral lines by selecting monochromator crystal size appropriately therefore eliminating need for the costly mismatched, two-crystal monochromator. The system imaging was fine-tuned for tungsten Kα{sub 1} line with the energy of 59.3 keV since it has been shown to be of great clinical significance by a number of researchers at synchrotron facilities. In this way a laboratory system that can be used for evaluating and quantifying tissue properties, initially explored at synchrotron facilities, would be of great interest to a larger research community. To demonstrate the imaging capability of our instrument we use a chicken thigh tissue sample.

  7. OsiriX: an open-source software for navigating in multidimensional DICOM images.

    Rosset, Antoine; Spadola, Luca; Ratib, Osman

    2004-09-01

    A multidimensional image navigation and display software was designed for display and interpretation of large sets of multidimensional and multimodality images such as combined PET-CT studies. The software is developed in Objective-C on a Macintosh platform under the MacOS X operating system using the GNUstep development environment. It also benefits from the extremely fast and optimized 3D graphic capabilities of the OpenGL graphic standard widely used for computer games optimized for taking advantage of any hardware graphic accelerator boards available. In the design of the software special attention was given to adapt the user interface to the specific and complex tasks of navigating through large sets of image data. An interactive jog-wheel device widely used in the video and movie industry was implemented to allow users to navigate in the different dimensions of an image set much faster than with a traditional mouse or on-screen cursors and sliders. The program can easily be adapted for very specific tasks that require a limited number of functions, by adding and removing tools from the program's toolbar and avoiding an overwhelming number of unnecessary tools and functions. The processing and image rendering tools of the software are based on the open-source libraries ITK and VTK. This ensures that all new developments in image processing that could emerge from other academic institutions using these libraries can be directly ported to the OsiriX program. OsiriX is provided free of charge under the GNU open-source licensing agreement at http://homepage.mac.com/rossetantoine/osirix.

  8. Optimum extracted H- and D- current densities from gas-pressure-limited high-power hydrogen/deuterium tandem ion sources

    Hiskes, J.R.

    1993-01-01

    The tandem hydrogen/deuterium ion source is modelled for the purpose of identifying the maximum current densities that can be extracted subject to the gas-pressure constraints proposed for contemporary beam-line systems. Optimum useful extracted current densities are found to be in the range of approximately 7 to 10 mA cm -2 . The sensitivity of these current densities is examined subject to uncertainties in the underlying atomic/molecular rate processes; A principal uncertainty remains the quantification of the molecular vibrational distribution following H 3 + wall collisions

  9. An Ultra-High Element Density pMUT Array with Low Crosstalk for 3-D Medical Imaging

    Tian-Ling Ren

    2013-07-01

    Full Text Available A ~1 MHz piezoelectric micromachined ultrasonic transducer (pMUT array with ultra-high element density and low crosstalk is proposed for the first time. This novel pMUT array is based on a nano-layer spin-coating lead zirconium titanium film technique and can be fabricated with high element density using a relatively simple process. Accordingly, key fabrication processes such as thick piezoelectric film deposition, low-stress Si-SOI bonding and bulk silicon removal have been successfully developed. The novel fine-pitch 6 × 6 pMUT arrays can all work at the desired frequency (~1 MHz with good uniformity, high performance and potential IC integration compatibility. The minimum interspace is ~20 μm, the smallest that has ever been achieved to the best of our knowledge. These arrays can be potentially used to steer ultrasound beams and implement high quality 3-D medical imaging applications.

  10. Imaging of noncarious cervical lesions by means of a fast swept source optical coherence tomography system

    Stoica, Eniko T.; Marcauteanu, Corina; Bradu, Adrian; Sinescu, Cosmin; Topala, Florin Ionel; Negrutiu, Meda Lavinia; Duma, Virgil Florin; Podoleanu, Adrian Gh.

    2014-01-01

    Non-carious cervical lesions (NCCL) are defined as the loss of tooth substance at the cemento-enamel junction and are caused by abrasion, erosion and/or occlusal overload. In this paper we proved that our fast swept source OCT system is a valuable tool to track the evolution of NCCL lesions in time. On several extracted bicuspids, four levels of NCCL were artificially created. After every level of induced lesion, OCT scanning was performed. B scans were acquired and 3D reconstructions were generated. The swept source OCT instrument used in this study has a central wavelength of 1050 nm, a sweeping range of 106 nm (measured at 10 dB), an average output power of 16 mW and a sweeping rate of 100 kHz. A depth resolution determined by the swept source of 12 μm in air was experimentally obtained. NCCL were measured on the B-scans as 2D images and 3D reconstructions (volumes). For quantitative evaluations of volumes, the Image J software was used. By calculating the areas of the amount of lost tissue corresponding to each difference of Bscans, the final volumes of NCCL were obtained. This swept source OCT method allows the dynamic diagnosis of NCCL in time.

  11. Pixel-based parametric source depth map for Cerenkov luminescence imaging

    Altabella, L.; Spinelli, A.E.; Boschi, F.

    2016-01-01

    Optical tomography represents a challenging problem in optical imaging because of the intrinsically ill-posed inverse problem due to photon diffusion. Cerenkov luminescence tomography (CLT) for optical photons produced in tissues by several radionuclides (i.e.: 32P, 18F, 90Y), has been investigated using both 3D multispectral approach and multiviews methods. Difficult in convergence of 3D algorithms can discourage to use this technique to have information of depth and intensity of source. For these reasons, we developed a faster 2D corrected approach based on multispectral acquisitions, to obtain source depth and its intensity using a pixel-based fitting of source intensity. Monte Carlo simulations and experimental data were used to develop and validate the method to obtain the parametric map of source depth. With this approach we obtain parametric source depth maps with a precision between 3% and 7% for MC simulation and 5–6% for experimental data. Using this method we are able to obtain reliable information about the source depth of Cerenkov luminescence with a simple and flexible procedure

  12. The first VLBI image of an infrared-faint radio source

    Middelberg, E.; Norris, R. P.; Tingay, S.; Mao, M. Y.; Phillips, C. J.; Hotan, A. W.

    2008-11-01

    Context: We investigate the joint evolution of active galactic nuclei and star formation in the Universe. Aims: In the 1.4 GHz survey with the Australia Telescope Compact Array of the Chandra Deep Field South and the European Large Area ISO Survey - S1 we have identified a class of objects which are strong in the radio but have no detectable infrared and optical counterparts. This class has been called Infrared-Faint Radio Sources, or IFRS. 53 sources out of 2002 have been classified as IFRS. It is not known what these objects are. Methods: To address the many possible explanations as to what the nature of these objects is we have observed four sources with the Australian Long Baseline Array. Results: We have detected and imaged one of the four sources observed. Assuming that the source is at a high redshift, we find its properties in agreement with properties of Compact Steep Spectrum sources. However, due to the lack of optical and infrared data the constraints are not particularly strong.

  13. Tracking brachytherapy sources using emission imaging with one flat panel detector

    Song Haijun; Bowsher, James; Das, Shiva; Yin Fangfang

    2009-01-01

    This work proposes to use the radiation from brachytherapy sources to track their dwell positions in three-dimensional (3D) space. The prototype device uses a single flat panel detector and a BB tray. The BBs are arranged in a defined pattern. The shadow of the BBs on the flat panel is analyzed to derive the 3D coordinates of the illumination source, i.e., the dwell position of the brachytherapy source. A kilovoltage x-ray source located 3.3 m away was used to align the center BB with the center pixel on the flat panel detector. For a test plan of 11 dwell positions, with an Ir-192 high dose rate unit, one projection was taken for each dwell point, and locations of the BB shadows were manually identified on the projection images. The 3D coordinates for the 11 dwell positions were reconstructed based on two BBs. The distances between dwell points were compared with the expected values. The average difference was 0.07 cm with a standard deviation of 0.15 cm. With automated BB shadow recognition in the future, this technique possesses the potential of tracking the 3D trajectory and the dwell times of a brachytherapy source in real time, enabling real time source position verification.

  14. Axonal diameter and density estimated with 7-Tesla hybrid diffusion imaging in transgenic Alzheimer rats

    Daianu, Madelaine; Jacobs, Russell E.; Town, Terrence; Thompson, Paul M.

    2016-01-01

    Diffusion-weighted MR imaging (DWI) is a powerful tool to study brain tissue microstructure. DWI is sensitive to subtle changes in the white matter (WM), and can provide insight into abnormal brain changes in diseases such as Alzheimer’s disease (AD). In this study, we used 7-Tesla hybrid diffusion imaging (HYDI) to scan 3 transgenic rats (line TgF344-AD; that model the full clinico-pathological spectrum of the human disease) ex vivo at 10, 15 and 24 months. We acquired 300 DWI volumes across...

  15. Elliptical Local Vessel Density: a Fast and Robust Quality Metric for Fundus Images

    Giancardo, Luca [ORNL; Chaum, Edward [ORNL; Karnowski, Thomas Paul [ORNL; Meriaudeau, Fabrice [ORNL; Tobin Jr, Kenneth William [ORNL; Abramoff, M.D. [University of Iowa

    2008-01-01

    A great effort of the research community is geared towards the creation of an automatic screening system able to promptly detect diabetic retinopathy with the use of fundus cameras. In addition, there are some documented approaches to the problem of automatically judging the image quality. We propose a new set of features independent of Field of View or resolution to describe the morphology of the patient's vessels. Our initial results suggest that they can be used to estimate the image quality in a time one order of magnitude shorter respect to previous techniques.

  16. Design of Programmable LED Controller with a Variable Current Source for 3D Image Display

    Kyung-Ryang Lee

    2014-12-01

    Full Text Available Conventional fluorescent light sources, as well as incandescent light sources are gradually being replaced by Light Emitting Diodes (LEDs for reducing power consumption in the image display area for multimedia application. An LED light source requires a controller with a low-power operation. In this paper, a low-power technique using adiabatic operation is applied for the implementation of LED controller with a stable constant-current, a low-power and low-heat function. From the simulation result, the power consumption of the proposed LED controller using adiabatic operation was reduced to about 87% in comparison with conventional operation with a constant VDD. The proposed circuit is expected to be an alternative LED controller which is sensitive to external conditions such as heat.

  17. Automated segmentation of white matter fiber bundles using diffusion tensor imaging data and a new density based clustering algorithm.

    Kamali, Tahereh; Stashuk, Daniel

    2016-10-01

    Robust and accurate segmentation of brain white matter (WM) fiber bundles assists in diagnosing and assessing progression or remission of neuropsychiatric diseases such as schizophrenia, autism and depression. Supervised segmentation methods are infeasible in most applications since generating gold standards is too costly. Hence, there is a growing interest in designing unsupervised methods. However, most conventional unsupervised methods require the number of clusters be known in advance which is not possible in most applications. The purpose of this study is to design an unsupervised segmentation algorithm for brain white matter fiber bundles which can automatically segment fiber bundles using intrinsic diffusion tensor imaging data information without considering any prior information or assumption about data distributions. Here, a new density based clustering algorithm called neighborhood distance entropy consistency (NDEC), is proposed which discovers natural clusters within data by simultaneously utilizing both local and global density information. The performance of NDEC is compared with other state of the art clustering algorithms including chameleon, spectral clustering, DBSCAN and k-means using Johns Hopkins University publicly available diffusion tensor imaging data. The performance of NDEC and other employed clustering algorithms were evaluated using dice ratio as an external evaluation criteria and density based clustering validation (DBCV) index as an internal evaluation metric. Across all employed clustering algorithms, NDEC obtained the highest average dice ratio (0.94) and DBCV value (0.71). NDEC can find clusters with arbitrary shapes and densities and consequently can be used for WM fiber bundle segmentation where there is no distinct boundary between various bundles. NDEC may also be used as an effective tool in other pattern recognition and medical diagnostic systems in which discovering natural clusters within data is a necessity. Copyright

  18. Evaluation of the Anisotropic Radiative Conductivity of a Low-Density Carbon Fiber Material from Realistic Microscale Imaging

    Nouri, Nima; Panerai, Francesco; Tagavi, Kaveh A.; Mansour, Nagi N.; Martin, Alexandre

    2015-01-01

    The radiative heat transfer inside a low-density carbon fiber insulator is analyzed using a three-dimensional direct simulation model. A robust procedure is presented for the numerical calculation of the geometric configuration factor to compute the radiative energy exchange processes among the small discretized surface areas of the fibrous material. The methodology is applied to a polygonal mesh of a fibrous insulator obtained from three-dimensional microscale imaging of the real material. The anisotropic values of the radiative conductivity are calculated for that geometry. The results yield both directional and thermal dependence of the radiative conductivity.

  19. The effect of fog on the probability density distribution of the ranging data of imaging laser radar

    Song, Wenhua; Lai, JianCheng; Ghassemlooy, Zabih; Gu, Zhiyong; Yan, Wei; Wang, Chunyong; Li, Zhenhua

    2018-02-01

    This paper outlines theoretically investigations of the probability density distribution (PDD) of ranging data for the imaging laser radar (ILR) system operating at a wavelength of 905 nm under the fog condition. Based on the physical model of the reflected laser pulses from a standard Lambertian target, a theoretical approximate model of PDD of the ranging data is developed under different fog concentrations, which offer improved precision target ranging and imaging. An experimental test bed for the ILR system is developed and its performance is evaluated using a dedicated indoor atmospheric chamber under homogeneously controlled fog conditions. We show that the measured results are in good agreement with both the accurate and approximate models within a given margin of error of less than 1%.

  20. The effect of fog on the probability density distribution of the ranging data of imaging laser radar

    Wenhua Song

    2018-02-01

    Full Text Available This paper outlines theoretically investigations of the probability density distribution (PDD of ranging data for the imaging laser radar (ILR system operating at a wavelength of 905 nm under the fog condition. Based on the physical model of the reflected laser pulses from a standard Lambertian target, a theoretical approximate model of PDD of the ranging data is developed under different fog concentrations, which offer improved precision target ranging and imaging. An experimental test bed for the ILR system is developed and its performance is evaluated using a dedicated indoor atmospheric chamber under homogeneously controlled fog conditions. We show that the measured results are in good agreement with both the accurate and approximate models within a given margin of error of less than 1%.

  1. Optimization of digital image processing to determine quantum dots' height and density from atomic force microscopy.

    Ruiz, J E; Paciornik, S; Pinto, L D; Ptak, F; Pires, M P; Souza, P L

    2018-01-01

    An optimized method of digital image processing to interpret quantum dots' height measurements obtained by atomic force microscopy is presented. The method was developed by combining well-known digital image processing techniques and particle recognition algorithms. The properties of quantum dot structures strongly depend on dots' height, among other features. Determination of their height is sensitive to small variations in their digital image processing parameters, which can generate misleading results. Comparing the results obtained with two image processing techniques - a conventional method and the new method proposed herein - with the data obtained by determining the height of quantum dots one by one within a fixed area, showed that the optimized method leads to more accurate results. Moreover, the log-normal distribution, which is often used to represent natural processes, shows a better fit to the quantum dots' height histogram obtained with the proposed method. Finally, the quantum dots' height obtained were used to calculate the predicted photoluminescence peak energies which were compared with the experimental data. Again, a better match was observed when using the proposed method to evaluate the quantum dots' height. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. DeepInfer: open-source deep learning deployment toolkit for image-guided therapy

    Mehrtash, Alireza; Pesteie, Mehran; Hetherington, Jorden; Behringer, Peter A.; Kapur, Tina; Wells, William M.; Rohling, Robert; Fedorov, Andriy; Abolmaesumi, Purang

    2017-03-01

    Deep learning models have outperformed some of the previous state-of-the-art approaches in medical image analysis. Instead of using hand-engineered features, deep models attempt to automatically extract hierarchical representations at multiple levels of abstraction from the data. Therefore, deep models are usually considered to be more flexible and robust solutions for image analysis problems compared to conventional computer vision models. They have demonstrated significant improvements in computer-aided diagnosis and automatic medical image analysis applied to such tasks as image segmentation, classification and registration. However, deploying deep learning models often has a steep learning curve and requires detailed knowledge of various software packages. Thus, many deep models have not been integrated into the clinical research work ows causing a gap between the state-of-the-art machine learning in medical applications and evaluation in clinical research procedures. In this paper, we propose "DeepInfer" - an open-source toolkit for developing and deploying deep learning models within the 3D Slicer medical image analysis platform. Utilizing a repository of task-specific models, DeepInfer allows clinical researchers and biomedical engineers to deploy a trained model selected from the public registry, and apply it to new data without the need for software development or configuration. As two practical use cases, we demonstrate the application of DeepInfer in prostate segmentation for targeted MRI-guided biopsy and identification of the target plane in 3D ultrasound for spinal injections.

  3. A Guillemin type E pulse forming network as the driver for a pulsed, high density plasma source.

    Rathod, Priyavandna J; Anitha, V P; Sholapurwala, Z H; Saxena, Y C

    2014-06-01

    A Guillemin type E pulse forming network (PFN) has been designed, developed, and tested for its application in generating high density (~1 × 10(18) m(-3)) plasmas. In the present study, plasma thus generated is utilized to investigate the interaction of high power microwaves (HPMs) with plasma in an experimental architecture known as SYMPLE (System for Microwave PLasma Experiment). Plasma discharges of ~100 μs (max) duration are to be produced, by delivering energy of 5 kJ stored in a PFN to the plasma source, a washer gun. The output of the PFN, in terms of its rise time, flat top and amplitude, needs to be tailored, depending on the experimental requirements. An ignitron (NL8900) trigger generator (ITG) is developed in-house to control the PFN discharge through the gun. This ITG is also to be used in a circuit that synchronizes the HPM and plasma shots, to ensure that HPM-plasma interaction takes place during a temporal regime where appropriate parametric conditions are satisfied. Hence it is necessary to retain the jitter within ±2.5 μs. Further, requirement on plasma quiescence (~10%) necessitates maintaining the ripple within 5%. The developmental work of the PFN, keeping in view the above criteria and the test results, is presented in this paper. The parameters of the PFN have been analytically approximated and verified with PSPICE simulation. The test results presented include rise time ~5-8 μs, flat top variable in the range 20-100 μs, ripple within ~1.5%, and jitter within ±2.5 μs, producing quiescent (plasma discharge meeting the experimental requirements.

  4. Influence of energy density of different light sources on knoop hardness of a dual-cured resin cement

    Evandro Piva

    2008-06-01

    Full Text Available The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs were tested: tungsten halogen light (HAL, light-emitting diode (LED and xenon plasma-arc (PAC lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce. Three energy doses were used by modifying the irradiance (I of each LCU and the irradiation time (T: 24 Jcm-2 (I/2x2T, 24 Jcm-2 (IxT and 48 Jcm-2 (Ix2T. Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus. Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10. Knoop hardness number (KHN means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (a=5%. Application of 48 J.cm-2 energy dose through the ceramic using LED (50.5±2.8 and HAL (50.9±3.7 produced significantly higher KHN means (p<0.05 than the control (44.7±3.8. LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.

  5. Current use of imaging and electromagnetic source localization procedures in epilepsy surgery centers across Europe.

    Mouthaan, Brian E; Rados, Matea; Barsi, Péter; Boon, Paul; Carmichael, David W; Carrette, Evelien; Craiu, Dana; Cross, J Helen; Diehl, Beate; Dimova, Petia; Fabo, Daniel; Francione, Stefano; Gaskin, Vladislav; Gil-Nagel, Antonio; Grigoreva, Elena; Guekht, Alla; Hirsch, Edouard; Hecimovic, Hrvoje; Helmstaedter, Christoph; Jung, Julien; Kalviainen, Reetta; Kelemen, Anna; Kimiskidis, Vasilios; Kobulashvili, Teia; Krsek, Pavel; Kuchukhidze, Giorgi; Larsson, Pål G; Leitinger, Markus; Lossius, Morten I; Luzin, Roman; Malmgren, Kristina; Mameniskiene, Ruta; Marusic, Petr; Metin, Baris; Özkara, Cigdem; Pecina, Hrvoje; Quesada, Carlos M; Rugg-Gunn, Fergus; Rydenhag, Bertil; Ryvlin, Philippe; Scholly, Julia; Seeck, Margitta; Staack, Anke M; Steinhoff, Bernhard J; Stepanov, Valentin; Tarta-Arsene, Oana; Trinka, Eugen; Uzan, Mustafa; Vogt, Viola L; Vos, Sjoerd B; Vulliémoz, Serge; Huiskamp, Geertjan; Leijten, Frans S S; Van Eijsden, Pieter; Braun, Kees P J

    2016-05-01

    In 2014 the European Union-funded E-PILEPSY project was launched to improve awareness of, and accessibility to, epilepsy surgery across Europe. We aimed to investigate the current use of neuroimaging, electromagnetic source localization, and imaging postprocessing procedures in participating centers. A survey on the clinical use of imaging, electromagnetic source localization, and postprocessing methods in epilepsy surgery candidates was distributed among the 25 centers of the consortium. A descriptive analysis was performed, and results were compared to existing guidelines and recommendations. Response rate was 96%. Standard epilepsy magnetic resonance imaging (MRI) protocols are acquired at 3 Tesla by 15 centers and at 1.5 Tesla by 9 centers. Three centers perform 3T MRI only if indicated. Twenty-six different MRI sequences were reported. Six centers follow all guideline-recommended MRI sequences with the proposed slice orientation and slice thickness or voxel size. Additional sequences are used by 22 centers. MRI postprocessing methods are used in 16 centers. Interictal positron emission tomography (PET) is available in 22 centers; all using 18F-fluorodeoxyglucose (FDG). Seventeen centers perform PET postprocessing. Single-photon emission computed tomography (SPECT) is used by 19 centers, of which 15 perform postprocessing. Four centers perform neither PET nor SPECT in children. Seven centers apply magnetoencephalography (MEG) source localization, and nine apply electroencephalography (EEG) source localization. Fourteen combinations of inverse methods and volume conduction models are used. We report a large variation in the presurgical diagnostic workup among epilepsy surgery centers across Europe. This diversity underscores the need for high-quality systematic reviews, evidence-based recommendations, and harmonization of available diagnostic presurgical methods. Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.

  6. Continuous representation of tumor microvessel density and detection of angiogenic hotspots in histological whole-slide images.

    Kather, Jakob Nikolas; Marx, Alexander; Reyes-Aldasoro, Constantino Carlos; Schad, Lothar R; Zöllner, Frank Gerrit; Weis, Cleo-Aron

    2015-08-07

    Blood vessels in solid tumors are not randomly distributed, but are clustered in angiogenic hotspots. Tumor microvessel density (MVD) within these hotspots correlates with patient survival and is widely used both in diagnostic routine and in clinical trials. Still, these hotspots are usually subjectively defined. There is no unbiased, continuous and explicit representation of tumor vessel distribution in histological whole slide images. This shortcoming distorts angiogenesis measurements and may account for ambiguous results in the literature. In the present study, we describe and evaluate a new method that eliminates this bias and makes angiogenesis quantification more objective and more efficient. Our approach involves automatic slide scanning, automatic image analysis and spatial statistical analysis. By comparing a continuous MVD function of the actual sample to random point patterns, we introduce an objective criterion for hotspot detection: An angiogenic hotspot is defined as a clustering of blood vessels that is very unlikely to occur randomly. We evaluate the proposed method in N=11 images of human colorectal carcinoma samples and compare the results to a blinded human observer. For the first time, we demonstrate the existence of statistically significant hotspots in tumor images and provide a tool to accurately detect these hotspots.

  7. Acquisition of an Advanced Thermal Analysis andImaging System for Integration with Interdisciplinary Researchand Education in Low Density Organic Inorganic Materials

    2017-12-02

    Report: Acquisition of an Advanced Thermal Analysis and Imaging System for Integration with Interdisciplinary Research and Education in Low Density...Agreement Number: W911NF-16-1-0475 Organization: University of Texas at El Paso Title: Acquisition of an Advanced Thermal Analysis and Imaging System ...for Integration with Interdisciplinary Research and Education in Low Density Organic-Inorganic Materials Report Term: 0-Other Email: dmisra2

  8. A cosmological model with compact space sections and low mass density

    Fagundes, H.V.

    1982-01-01

    A general relativistic cosmological model is presented, which has closed space sections and mass density below a critical density similar to that of Friedmann's models. The model may predict double images of cosmic sources. (Author) [pt

  9. Dust Density Distribution and Imaging Analysis of Different Ice Lines in Protoplanetary Disks

    Pinilla, P. [Department of Astronomy/Steward Observatory, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Pohl, A. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Stammler, S. M.; Birnstiel, T., E-mail: pinilla@email.arizona.edu [University Observatory, Faculty of Physics, Ludwig-Maximilians-Universität München, Scheinerstr. 1, D-81679 Münich (Germany)

    2017-08-10

    Recent high angular resolution observations of protoplanetary disks at different wavelengths have revealed several kinds of structures, including multiple bright and dark rings. Embedded planets are the most used explanation for such structures, but there are alternative models capable of shaping the dust in rings as it has been observed. We assume a disk around a Herbig star and investigate the effect that ice lines have on the dust evolution, following the growth, fragmentation, and dynamics of multiple dust size particles, covering from 1 μ m to 2 m sized objects. We use simplified prescriptions of the fragmentation velocity threshold, which is assumed to change radially at the location of one, two, or three ice lines. We assume changes at the radial location of main volatiles, specifically H{sub 2}O, CO{sub 2}, and NH{sub 3}. Radiative transfer calculations are done using the resulting dust density distributions in order to compare with current multiwavelength observations. We find that the structures in the dust density profiles and radial intensities at different wavelengths strongly depend on the disk viscosity. A clear gap of emission can be formed between ice lines and be surrounded by ring-like structures, in particular between the H{sub 2}O and CO{sub 2} (or CO). The gaps are expected to be shallower and narrower at millimeter emission than at near-infrared, opposite to model predictions of particle trapping. In our models, the total gas surface density is not expected to show strong variations, in contrast to other gap-forming scenarios such as embedded giant planets or radial variations of the disk viscosity.

  10. High-resolution SMA imaging of bright submillimetre sources from the SCUBA-2 Cosmology Legacy Survey

    Hill, Ryley; Chapman, Scott C.; Scott, Douglas; Petitpas, Glen; Smail, Ian; Chapin, Edward L.; Gurwell, Mark A.; Perry, Ryan; Blain, Andrew W.; Bremer, Malcolm N.; Chen, Chian-Chou; Dunlop, James S.; Farrah, Duncan; Fazio, Giovanni G.; Geach, James E.; Howson, Paul; Ivison, R. J.; Lacaille, Kevin; Michałowski, Michał J.; Simpson, James M.; Swinbank, A. M.; van der Werf, Paul P.; Wilner, David J.

    2018-06-01

    We have used the Submillimeter Array (SMA) at 860 μm to observe the brightest sources in the Submillimeter Common User Bolometer Array-2 (SCUBA-2) Cosmology Legacy Survey (S2CLS). The goal of this survey is to exploit the large field of the S2CLS along with the resolution and sensitivity of the SMA to construct a large sample of these rare sources and to study their statistical properties. We have targeted 70 of the brightest single-dish SCUBA-2 850 μm sources down to S850 ≈ 8 mJy, achieving an average synthesized beam of 2.4 arcsec and an average rms of σ860 = 1.5 mJy beam-1 in our primary beam-corrected maps. We searched our SMA maps for 4σ peaks, corresponding to S860 ≳ 6 mJy sources, and detected 62, galaxies, including three pairs. We include in our study 35 archival observations, bringing our sample size to 105 bright single-dish submillimetre sources with interferometric follow-up. We compute the cumulative and differential number counts, finding them to overlap with previous single-dish survey number counts within the uncertainties, although our cumulative number count is systematically lower than the parent S2CLS cumulative number count by 14 ± 6 per cent between 11 and 15 mJy. We estimate the probability that a ≳10 mJy single-dish submillimetre source resolves into two or more galaxies with similar flux densities to be less than 15 per cent. Assuming the remaining 85 per cent of the targets are ultraluminous starburst galaxies between z = 2 and 3, we find a likely volume density of ≳400 M⊙ yr-1 sources to be {˜ } 3^{+0.7}_{-0.6} {× } 10^{-7} Mpc-3. We show that the descendants of these galaxies could be ≳4 × 1011 M⊙ local quiescent galaxies, and that about 10 per cent of their total stellar mass would have formed during these short bursts of star formation.

  11. Advances in Mineral Dust Source Composition Measurement with Imaging Spectroscopy at the Salton Sea, CA

    Green, R. O.; Realmuto, V. J.; Thompson, D. R.; Mahowald, N. M.; Pérez García-Pando, C.; Miller, R. L.; Clark, R. N.; Swayze, G. A.; Okin, G. S.

    2015-12-01

    Mineral dust emitted from the Earth's surface is a principal contributor to direct radiative forcing over the arid regions, where shifts in climate have a significant impact on agriculture, precipitation, and desert encroachment around the globe. Dust particles contribute to both positive and negative forcing, depending on the composition of the particles. Particle composition is a function of the surface mineralogy of dust source regions, but poor knowledge of surface mineralogy on regional to global scales limits the skill of Earth System models to predict shifts in regional climate around the globe. Earth System models include the source, emission, transport and deposition phases of the dust cycle. In addition to direct radiative forcing contributions, mineral dust impacts include indirect radiative forcing, modification of the albedo and melting rates of snow and ice, kinetics of tropospheric photochemistry, formation and deposition of acidic aerosols, supply of nutrients to aquatic and terrestrial ecosystems, and impact on human health and safety. We demonstrate the ability to map mineral dust source composition in the Salton Sea dust source region with imaging spectroscopy measurements acquired as part of the NASA HyspIRI preparatory airborne campaign. These new spectroscopically derived compositional measurements provide a six orders of magnitude improvement over current atlases for this dust source region and provide a pathfinder example for a remote measurement approach to address this critical dust composition gap for global Earth System models.

  12. A technique to consider mismatches between fMRI and EEG/MEG sources for fMRI-constrained EEG/MEG source imaging: a preliminary simulation study

    Im, Chang-Hwan; Lee, Soo Yeol

    2006-01-01

    fMRI-constrained EEG/MEG source imaging can be a powerful tool in studying human brain functions with enhanced spatial and temporal resolutions. Recent studies on the combination of fMRI and EEG/MEG have suggested that fMRI prior information could be readily implemented by simply imposing different weighting factors to cortical sources overlapping with the fMRI activations. It has been also reported, however, that such a hard constraint may cause severe distortions or elimination of meaningful EEG/MEG sources when there are distinct mismatches between the fMRI activations and the EEG/MEG sources. If one wants to obtain the actual EEG/MEG source locations and uses the fMRI prior information as just an auxiliary tool to enhance focality of the distributed EEG/MEG sources, it is reasonable to weaken the strength of fMRI constraint when severe mismatches between fMRI and EEG/MEG sources are observed. The present study suggests an efficient technique to automatically adjust the strength of fMRI constraint according to the mismatch level. The use of the proposed technique rarely affects the results of conventional fMRI-constrained EEG/MEG source imaging if no major mismatch between the two modalities is detected; while the new results become similar to those of typical EEG/MEG source imaging without fMRI constraint if the mismatch level is significant. A preliminary simulation study using realistic EEG signals demonstrated that the proposed technique can be a promising tool to selectively apply fMRI prior information to EEG/MEG source imaging

  13. Anser EMT: the first open-source electromagnetic tracking platform for image-guided interventions.

    Jaeger, Herman Alexander; Franz, Alfred Michael; O'Donoghue, Kilian; Seitel, Alexander; Trauzettel, Fabian; Maier-Hein, Lena; Cantillon-Murphy, Pádraig

    2017-06-01

    Electromagnetic tracking is the gold standard for instrument tracking and navigation in the clinical setting without line of sight. Whilst clinical platforms exist for interventional bronchoscopy and neurosurgical navigation, the limited flexibility and high costs of electromagnetic tracking (EMT) systems for research investigations mitigate against a better understanding of the technology's characterisation and limitations. The Anser project provides an open-source implementation for EMT with particular application to image-guided interventions. This work provides implementation schematics for our previously reported EMT system which relies on low-cost acquisition and demodulation techniques using both National Instruments and Arduino hardware alongside MATLAB support code. The system performance is objectively compared to other commercial tracking platforms using the Hummel assessment protocol. Positional accuracy of 1.14 mm and angular rotation accuracy of [Formula: see text] are reported. Like other EMT platforms, Anser is susceptible to tracking errors due to eddy current and ferromagnetic distortion. The system is compatible with commercially available EMT sensors as well as the Open Network Interface for image-guided therapy (OpenIGTLink) for easy communication with visualisation and medical imaging toolkits such as MITK and 3D Slicer. By providing an open-source platform for research investigations, we believe that novel and collaborative approaches can overcome the limitations of current EMT technology.

  14. Self characterization of a coded aperture array for neutron source imaging

    Volegov, P. L., E-mail: volegov@lanl.gov; Danly, C. R.; Guler, N.; Merrill, F. E.; Wilde, C. H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Fittinghoff, D. N. [Livermore National Laboratory, Livermore, California 94550 (United States)

    2014-12-15

    The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the stagnation stage of inertial confinement fusion implosions. Since the neutron source is small (∼100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be precisely aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF.

  15. Computerized tomography using high resolution X-ray imaging system with a microfocus source

    Zaprazny, Z.; Korytar, D.; Konopka, P.; Ac, V.; Bielecki, J.

    2011-01-01

    In recent years there is an effort to image an internal structure of an object by using not only conventional 2D X-ray radiography but also using high resolution 3D tomography which is based on reconstruction of multiple 2D projections at various angular positions of the object. We have previously reported [1] the development and basic parameters of a high resolution x-ray imaging system with a microfocus source. We report the recent progress using this high resolution X-ray laboratory system in this work. These first findings show that our system is particularly suitable for light weight and nonmetallic objects such as biological objects, plastics, wood, paper, etc. where phase contrast helps to increase the visibility of the finest structures of the object. Phase-contrast X-ray Computerized Tomography is of our special interest because it is an emerging imaging technique that can be implemented at third generation synchrotron radiation sources and also in laboratory conditions using a microfocus X-ray tube or beam conditioning optics. (authors)

  16. High speed imaging of dynamic processes with a switched source x-ray CT system

    Thompson, William M; Lionheart, William R B; Morton, Edward J; Cunningham, Mike; Luggar, Russell D

    2015-01-01

    Conventional x-ray computed tomography (CT) scanners are limited in their scanning speed by the mechanical constraints of their rotating gantries and as such do not provide the necessary temporal resolution for imaging of fast-moving dynamic processes, such as moving fluid flows. The Real Time Tomography (RTT) system is a family of fast cone beam CT scanners which instead use multiple fixed discrete sources and complete rings of detectors in an offset geometry. We demonstrate the potential of this system for use in the imaging of such high speed dynamic processes and give results using simulated and real experimental data. The unusual scanning geometry results in some challenges in image reconstruction, which are overcome using algebraic iterative reconstruction techniques and explicit regularisation. Through the use of a simple temporal regularisation term and by optimising the source firing pattern, we show that temporal resolution of the system may be increased at the expense of spatial resolution, which may be advantageous in some situations. Results are given showing temporal resolution of approximately 500 µs with simulated data and 3 ms with real experimental data. (paper)

  17. Atomic processes, cross sections, and reaction rates necessary for modelling hydrogen-negative-ion sources and identification of optimum H- current densities

    Hiskes, J.R.

    1991-01-01

    The principal electron excitation cross sections for vibrational excitation in a hydrogen discharge are reported. In the first chamber of a two-chamber hydrogen negative-ion-source system subject to the beam-line constraint of a maximum gas pressure, the density of vibrationally excited molecules reaches an asymptote for increasing discharge current or the equivalent fast electron density. Operating near this first-chamber asymptote, there exists a spatially-dependent maximum negative-ion density in the second chamber. With the extraction grid placed at this maximum the optimum performance of a hydrogen-based system is determined. This optimum performance provides a criterion for the selection of differing source types for fusion applications

  18. CO2 laser imaging heterodyne and phase contrast interferometer for density profile and fluctuation measurements in LHD

    Tanaka, K.; Michael, C.; Akiyama, T.; Kawahata, K.; Ito, Y.; Vyacheslavov, L.N.; Sanin, A.L.; Okajima, S.

    2007-01-01

    A CO 2 laser heterodyne imaging interferometer (CO 2 HI) and a CO 2 laser phase contrast imaging interferometer (CO 2 PCI) were installed in LHD. The purpose of CO 2 HI is to measure electron density profile at high density (>1x10 20 m -3 ), where the existing far infrared laser (wavelength 118.9 μm) interferometer suffers from fringe jump due to the reduction of signal intensity caused by refraction. In the beginning of 10th LHD experimental campaign (2006-2007), sixty three three of CO 2 HI with 10 channels of YAG HI for vibration compensation, and in the later of 10th LHD experimental campaign. Eighty one channels CO 2 HI and 15 channels YAG HI became available. The purpose of CO 2 PCI is to measure turbulent fluctuation, which can contribute to the energy and particle transport. In order to get local fluctuation information, magnetic shear technique was applied with use of 48 (6 by 8) channel two dimensional detector. (author)

  19. Development and validation of a combined phased acoustical radiosity and image source model for predicting