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Sample records for 2-d temperature imaging

  1. 2-D Imaging of Electron Temperature in Tokamak Plasmas

    SciTech Connect

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

    2004-07-08

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

  2. Real-time 2-D temperature imaging using ultrasound.

    PubMed

    Liu, Dalong; Ebbini, Emad S

    2010-01-01

    We have previously introduced methods for noninvasive estimation of temperature change using diagnostic ultrasound. The basic principle was validated both in vitro and in vivo by several groups worldwide. Some limitations remain, however, that have prevented these methods from being adopted in monitoring and guidance of minimally invasive thermal therapies, e.g., RF ablation and high-intensity-focused ultrasound (HIFU). In this letter, we present first results from a real-time system for 2-D imaging of temperature change using pulse-echo ultrasound. The front end of the system is a commercially available scanner equipped with a research interface, which allows the control of imaging sequence and access to the RF data in real time. A high-frame-rate 2-D RF acquisition mode, M2D, is used to capture the transients of tissue motion/deformations in response to pulsed HIFU. The M2D RF data is streamlined to the back end of the system, where a 2-D temperature imaging algorithm based on speckle tracking is implemented on a graphics processing unit. The real-time images of temperature change are computed on the same spatial and temporal grid of the M2D RF data, i.e., no decimation. Verification of the algorithm was performed by monitoring localized HIFU-induced heating of a tissue-mimicking elastography phantom. These results clearly demonstrate the repeatability and sensitivity of the algorithm. Furthermore, we present in vitro results demonstrating the possible use of this algorithm for imaging changes in tissue parameters due to HIFU-induced lesions. These results clearly demonstrate the value of the real-time data streaming and processing in monitoring, and guidance of minimally invasive thermotherapy. PMID:19884075

  3. 2D electron temperature diagnostic using soft x-ray imaging technique

    SciTech Connect

    Nishimura, K. Sanpei, A. Tanaka, H.; Ishii, G.; Kodera, R.; Ueba, R.; Himura, H.; Masamune, S.; Ohdachi, S.; Mizuguchi, N.

    2014-03-15

    We have developed a two-dimensional (2D) electron temperature (T{sub e}) diagnostic system for thermal structure studies in a low-aspect-ratio reversed field pinch (RFP). The system consists of a soft x-ray (SXR) camera with two pin holes for two-kinds of absorber foils, combined with a high-speed camera. Two SXR images with almost the same viewing area are formed through different absorber foils on a single micro-channel plate (MCP). A 2D T{sub e} image can then be obtained by calculating the intensity ratio for each element of the images. We have succeeded in distinguishing T{sub e} image in quasi-single helicity (QSH) from that in multi-helicity (MH) RFP states, where the former is characterized by concentrated magnetic fluctuation spectrum and the latter, by broad spectrum of edge magnetic fluctuations.

  4. Infrared imaging of 2-D temperature distribution during cryogen spray cooling.

    PubMed

    Choi, Bernard; Welch, Ashley J

    2002-12-01

    Cryogen spray cooling (CSC) is used in conjunction with pulsed laser irradiation for treatment of dermatologic indications. The main goal of this study was to determine the radial temperature distribution created by CSC and evaluate the importance of radial temperature gradients upon the subsequent analysis of tissue cooling throughout the skin. Since direct measurement of surface temperatures during CSC are hindered by the formation of a liquid cryogen layer, temperature distributions were estimated using a thin, black aluminum sheet. An infrared focal plane array camera was used to determine the 2-D backside temperature distribution during a cryogen spurt, which preliminary measurements have shown is a good indicator of the front-side temperature distribution. The measured temperature distribution was approximately gaussian in shape. Next, the transient temperature distributions in skin were calculated for two cases: 1) the standard 1-D solution which assumes a uniform cooling temperature distribution, and 2) a 2-D solution using a nonuniform surface cooling temperature distribution based upon the back-side infrared temperature measurements. At the end of a 100-ms cryogen spurt, calculations showed that, for the two cases, large discrepancies in temperatures at the surface and at a 60-micron depth were found at radii greater than 2.5 mm. These results suggest that it is necessary to consider radial temperature gradients during cryogen spray cooling of tissue. PMID:12596634

  5. Noninvasive real-time 2D imaging of temperature distribution during the plastic pellet cooling process by using electrical capacitance tomography

    NASA Astrophysics Data System (ADS)

    Hirose, Yusuke; Sapkota, Achyut; Sugawara, Michiko; Takei, Masahiro

    2016-01-01

    This study has launched a concept to image a real-time 2D temperature distribution noninvasively by a combination of the electrical capacitance tomography (ECT) technique and a permittivity-temperature calibration equation for the plastic pellet cooling process. The concept has two steps, which are the relative permittivity calculation from the measured capacitance among the many electrodes by the ECT technique, and the temperature distribution imaging from the relative permittivity by the permittivity-temperature calibration equation. An ECT sensor with 12 electrodes was designed to image the cross-sectional temperature distribution during the polymethyl methacrylate pellets cooling process. The images of temperature distribution were successfully reconstructed from the relative permittivity distribution at every time step during the process. The images reasonably indicate the temperature diffusion in a 2D space and time within a 0.0065 and 0.0175 time-dependent temperature deviation, as compared to an analytical thermal conductance simulation and thermocouple measurement.

  6. Staring 2-D hadamard transform spectral imager

    DOEpatents

    Gentry, Stephen M.; Wehlburg, Christine M.; Wehlburg, Joseph C.; Smith, Mark W.; Smith, Jody L.

    2006-02-07

    A staring imaging system inputs a 2D spatial image containing multi-frequency spectral information. This image is encoded in one dimension of the image with a cyclic Hadamarid S-matrix. The resulting image is detecting with a spatial 2D detector; and a computer applies a Hadamard transform to recover the encoded image.

  7. 2D Imaging of ELM Structures Using Microwave Imaging Reflectometry

    NASA Astrophysics Data System (ADS)

    Hoffmann, Hannah; Tobias, B. J.

    2015-11-01

    2D images of density perturbations due to plasma edge instabilities have been obtained using microwave imaging reflectometry (MIR). Edge-localized modes (ELMs) are fast-growing instabilities that can locally deposit heat and particles, which can be very detrimental to plasma-facing components. The mitigation and suppression of these instabilities on ITER is therefore an area of active research. Prior attempts to image temperature perturbations of ELMs with the electron-cyclotron emission imaging (ECEI) diagnostic were confounded by unexplained ``bursts'' of intense millimeter wave emission. However, MIR is not sensitive to these bursts, and provides long-sought 2D density fluctuation data. Using this data, changes in mode structure have been correlated with changes in ELM behavior, providing important insights into possible methods of ELM control. Additionally, by simultaneously using ECEI we can explore the relationship between mode structure and the bursts. Supported in part by US DOE under DE-FC02-04ER54698.

  8. Tomosynthesis imaging with 2D scanning trajectories

    NASA Astrophysics Data System (ADS)

    Khare, Kedar; Claus, Bernhard E. H.; Eberhard, Jeffrey W.

    2011-03-01

    Tomosynthesis imaging in chest radiography provides volumetric information with the potential for improved diagnostic value when compared to the standard AP or LAT projections. In this paper we explore the image quality benefits of 2D scanning trajectories when coupled with advanced image reconstruction approaches. It is intuitively clear that 2D trajectories provide projection data that is more complete in terms of Radon space filling, when compared with conventional tomosynthesis using a linearly scanned source. Incorporating this additional information for obtaining improved image quality is, however, not a straightforward problem. The typical tomosynthesis reconstruction algorithms are based on direct inversion methods e.g. Filtered Backprojection (FBP) or iterative algorithms that are variants of the Algebraic Reconstruction Technique (ART). The FBP approach is fast and provides high frequency details in the image but at the same time introduces streaking artifacts degrading the image quality. The iterative methods can reduce the image artifacts by using image priors but suffer from a slow convergence rate, thereby producing images lacking high frequency details. In this paper we propose using a fast converging optimal gradient iterative scheme that has advantages of both the FBP and iterative methods in that it produces images with high frequency details while reducing the image artifacts. We show that using favorable 2D scanning trajectories along with the proposed reconstruction method has the advantage of providing improved depth information for structures such as the spine and potentially producing images with more isotropic resolution.

  9. 2D microwave imaging reflectometer electronics.

    PubMed

    Spear, A G; Domier, C W; Hu, X; Muscatello, C M; Ren, X; Tobias, B J; Luhmann, N C

    2014-11-01

    A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program. PMID:25430247

  10. 2D microwave imaging reflectometer electronics

    SciTech Connect

    Spear, A. G.; Domier, C. W. Hu, X.; Muscatello, C. M.; Ren, X.; Luhmann, N. C.; Tobias, B. J.

    2014-11-15

    A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program.

  11. Adaptive stereoscopic image conversion of 2D image

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Ho; Kim, Jung-Jin; Kim, Eun-Soo

    2001-11-01

    In recent years, there have been many researches being done throughout the world on the 3D image conversion of 2D image. However, 3D image conversion of 2D image has many problems on obtaining the optimal stereopsis. Stereopsis is dominated to relative position of several objects and depth information within image. Accordingly, in this paper, as a new adaptive scheme for stereoscopic image conversion of 2D image is suggested. Two input images acquired by Stereo Camera have different disparity information to each other. Disparity map, based on disparity information, presents mutually different occulusion region in the left/right image. These depend on the left view & right view and front & rear view of the virtual image plane. If arbitrary threshold values are applied to disparity map, we can get segmented objects from the input image. Using the principle of horizontal parallax, segmented objects are shifted with optimal screen disparity. In this case, we can improve stereopsis by differential shifting.

  12. 2D stepping microdrive for hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Endrödy, Csaba; Mehner, Hannes; Grewe, Adrian; Sinzinger, Stefan; Hoffmann, Martin

    2015-05-01

    In a novel hyperspectral imaging concept based on confocal chromatic microscopy, a pinhole array (matrix of pinholes) has to be scanned across an intermediate image plane to capture the full object plane. In this paper a two-axis stepping microdrive is presented for the pinhole array (6×7.5×0.2 mm3 of glass, weight 20 mg), featuring a 10 μm step size and a 200 μm displacement range in each direction. With the two-axis stepwise actuation of the pinhole array, the imaged area of the object plane is increased from 7% (fixed pinhole array) up to 89% with actuated array. The two-axis positioning is implemented with a three-axis inchworm motion driven by electrostatic forces. A combination of horizontal and vertical electrostatic actuators are arranged to achieve a precise in-plane actuation of the pinhole array. The microdrive is fabricated with established MEMS technologies and features a size about 1 cm2 with 1 mm thickness. The microdrive is capable to position the pinhole array over the displacement range. The array size enables a 1:1 optical imaging on an 8 mm diagonal size CCD. The presented stepping microdrive outperforms existing microsystem solutions with a combination of high payload, large step size, displacement range, and the large optical aperture. Furthermore, the device concept enables the positioning of milligram weights with a highly integrated microsystem.

  13. Photorealistic image synthesis and camera validation from 2D images

    NASA Astrophysics Data System (ADS)

    Santos Ferrer, Juan C.; González Chévere, David; Manian, Vidya

    2014-06-01

    This paper presents a new 3D scene reconstruction technique using the Unity 3D game engine. The method presented here allow us to reconstruct the shape of simple objects and more complex ones from multiple 2D images, including infrared and digital images from indoor scenes and only digital images from outdoor scenes and then add the reconstructed object to the simulated scene created in Unity 3D, these scenes are then validated with real world scenes. The method used different cameras settings and explores different properties in the reconstructions of the scenes including light, color, texture, shapes and different views. To achieve the highest possible resolution, it was necessary the extraction of partial textures from visible surfaces. To recover the 3D shapes and the depth of simple objects that can be represented by the geometric bodies, there geometric characteristics were used. To estimate the depth of more complex objects the triangulation method was used, for this the intrinsic and extrinsic parameters were calculated using geometric camera calibration. To implement the methods mentioned above the Matlab tool was used. The technique presented here also let's us to simulate small simple videos, by reconstructing a sequence of multiple scenes of the video separated by small margins of time. To measure the quality of the reconstructed images and video scenes the Fast Low Band Model (FLBM) metric from the Video Quality Measurement (VQM) software was used. Low bandwidth perception based features include edges and motion.

  14. Optical imaging systems analyzed with a 2D template.

    PubMed

    Haim, Harel; Konforti, Naim; Marom, Emanuel

    2012-05-10

    Present determination of optical imaging systems specifications are based on performance values and modulation transfer function results carried with a 1D resolution template (such as the USAF resolution target or spoke templates). Such a template allows determining image quality, resolution limit, and contrast. Nevertheless, the conventional 1D template does not provide satisfactory results, since most optical imaging systems handle 2D objects for which imaging system response may be different by virtue of some not readily observable spatial frequencies. In this paper we derive and analyze contrast transfer function results obtained with 1D as well as 2D templates. PMID:22614498

  15. Sparse radar imaging using 2D compressed sensing

    NASA Astrophysics Data System (ADS)

    Hou, Qingkai; Liu, Yang; Chen, Zengping; Su, Shaoying

    2014-10-01

    Radar imaging is an ill-posed linear inverse problem and compressed sensing (CS) has been proved to have tremendous potential in this field. This paper surveys the theory of radar imaging and a conclusion is drawn that the processing of ISAR imaging can be denoted mathematically as a problem of 2D sparse decomposition. Based on CS, we propose a novel measuring strategy for ISAR imaging radar and utilize random sub-sampling in both range and azimuth dimensions, which will reduce the amount of sampling data tremendously. In order to handle 2D reconstructing problem, the ordinary solution is converting the 2D problem into 1D by Kronecker product, which will increase the size of dictionary and computational cost sharply. In this paper, we introduce the 2D-SL0 algorithm into the reconstruction of imaging. It is proved that 2D-SL0 can achieve equivalent result as other 1D reconstructing methods, but the computational complexity and memory usage is reduced significantly. Moreover, we will state the results of simulating experiments and prove the effectiveness and feasibility of our method.

  16. Integer characterization of 2D topological insulators at finite temperature

    NASA Astrophysics Data System (ADS)

    Huang, Zhoushen; Arovas, Daniel

    2014-03-01

    2D band topological insulators (TI) are characterized by the TKNN number and its variants. However, this only works for zero temperature as the TKNN number is no longer quantized for T > 0 . We show that using Uhlmann's parallel transport for density matrices, TI at finite temperature can still be characterized by an integer, which (1) reduces to the corresponding TKNN number at T = 0 , and (2) exhibits a phase transition, i.e. drops to zero, at a critical temperature. Prototypical models such as Haldane's honeycomb lattice model and the Bernevig-Hughs-Zhang model will be discussed.

  17. Improvement of LIEF by wavelength-resolved acquisition of multiple images using a single CCD detector - Simultaneous 2D measurement of air/fuel ratio, temperature distribution of the liquid phase and qualitative distribution of the liquid phase with the Multi-2D technique

    NASA Astrophysics Data System (ADS)

    Wieske, P.; Wissel, S.; Grünefeld, G.; Pischinger, S.

    2006-05-01

    The exciplex tracer system fluorobenzene (FB) and diethyl-methyl-amine (DEMA) in a solution of n-hexane and methyl-tert.-butylether (MTBE) was used to investigate the mixture formation in a fired direct injection spark ignition engine. The scope of this paper is the recently developed Multi-2D technique, which allows for the simultaneous measurement of the local air/fuel ratio (λ-distribution of the vapor phase), the qualitative distribution of the liquid phase, the temperature distribution of the liquid phase, and the detection of Mie scattering in this application. Basically, the Multi-2D technique consists of a new optical setup, which images the same field of view four times onto one camera, thus combining spatial and spectral resolution based on interference filters. The liquid temperature is derived via “two-line” thermometry. Using the liquid phase temperature the crosstalk from the liquid into the spectral detection range of the vapor phase is corrected. Quantitative results of the crosstalk-corrected vapor phase signals are achieved by an in-situ calibration.

  18. Semiregular solid texturing from 2D image exemplars.

    PubMed

    Du, Song-Pei; Hu, Shi-Min; Martin, Ralph R

    2013-03-01

    Solid textures, comprising 3D particles embedded in a matrix in a regular or semiregular pattern, are common in natural and man-made materials, such as brickwork, stone walls, plant cells in a leaf, etc. We present a novel technique for synthesizing such textures, starting from 2D image exemplars which provide cross-sections of the desired volume texture. The shapes and colors of typical particles embedded in the structure are estimated from their 2D cross-sections. Particle positions in the texture images are also used to guide spatial placement of the 3D particles during synthesis of the 3D texture. Our experiments demonstrate that our algorithm can produce higher quality structures than previous approaches; they are both compatible with the input images, and have a plausible 3D nature. PMID:22614330

  19. Interactive 2D to 3D stereoscopic image synthesis

    NASA Astrophysics Data System (ADS)

    Feldman, Mark H.; Lipton, Lenny

    2005-03-01

    Advances in stereoscopic display technologies, graphic card devices, and digital imaging algorithms have opened up new possibilities in synthesizing stereoscopic images. The power of today"s DirectX/OpenGL optimized graphics cards together with adapting new and creative imaging tools found in software products such as Adobe Photoshop, provide a powerful environment for converting planar drawings and photographs into stereoscopic images. The basis for such a creative process is the focus of this paper. This article presents a novel technique, which uses advanced imaging features and custom Windows-based software that utilizes the Direct X 9 API to provide the user with an interactive stereo image synthesizer. By creating an accurate and interactive world scene with moveable and flexible depth map altered textured surfaces, perspective stereoscopic cameras with both visible frustums and zero parallax planes, a user can precisely model a virtual three-dimensional representation of a real-world scene. Current versions of Adobe Photoshop provide a creative user with a rich assortment of tools needed to highlight elements of a 2D image, simulate hidden areas, and creatively shape them for a 3D scene representation. The technique described has been implemented as a Photoshop plug-in and thus allows for a seamless transition of these 2D image elements into 3D surfaces, which are subsequently rendered to create stereoscopic views.

  20. Quantifying Therapeutic and Diagnostic Efficacy in 2D Microvascular Images

    NASA Technical Reports Server (NTRS)

    Parsons-Wingerter, Patricia; Vickerman, Mary B.; Keith, Patricia A.

    2009-01-01

    VESGEN is a newly automated, user-interactive program that maps and quantifies the effects of vascular therapeutics and regulators on microvascular form and function. VESGEN analyzes two-dimensional, black and white vascular images by measuring important vessel morphology parameters. This software guides the user through each required step of the analysis process via a concise graphical user interface (GUI). Primary applications of the VESGEN code are 2D vascular images acquired as clinical diagnostic images of the human retina and as experimental studies of the effects of vascular regulators and therapeutics on vessel remodeling.

  1. 2D luminescence imaging of pH in vivo

    PubMed Central

    Schreml, Stephan; Meier, Robert J.; Wolfbeis, Otto S.; Landthaler, Michael; Szeimies, Rolf-Markus; Babilas, Philipp

    2011-01-01

    Luminescence imaging of biological parameters is an emerging field in biomedical sciences. Tools to study 2D pH distribution are needed to gain new insights into complex disease processes, such as wound healing and tumor metabolism. In recent years, luminescence-based methods for pH measurement have been developed. However, for in vivo applications, especially for studies on humans, biocompatibility and reliability under varying conditions have to be ensured. Here, we present a referenced luminescent sensor for 2D high-resolution imaging of pH in vivo. The ratiometric sensing scheme is based on time-domain luminescence imaging of FITC and ruthenium(II)tris-(4,7-diphenyl-1,10-phenanthroline). To create a biocompatible 2D sensor, these dyes were bound to or incorporated into microparticles (aminocellulose and polyacrylonitrile), and particles were immobilized in polyurethane hydrogel on transparent foils. We show sensor precision and validity by conducting in vitro and in vivo experiments, and we show the versatility in imaging pH during physiological and chronic cutaneous wound healing in humans. Implementation of this technique may open vistas in wound healing, tumor biology, and other biomedical fields. PMID:21262842

  2. 2D luminescence imaging of pH in vivo.

    PubMed

    Schreml, Stephan; Meier, Robert J; Wolfbeis, Otto S; Landthaler, Michael; Szeimies, Rolf-Markus; Babilas, Philipp

    2011-02-01

    Luminescence imaging of biological parameters is an emerging field in biomedical sciences. Tools to study 2D pH distribution are needed to gain new insights into complex disease processes, such as wound healing and tumor metabolism. In recent years, luminescence-based methods for pH measurement have been developed. However, for in vivo applications, especially for studies on humans, biocompatibility and reliability under varying conditions have to be ensured. Here, we present a referenced luminescent sensor for 2D high-resolution imaging of pH in vivo. The ratiometric sensing scheme is based on time-domain luminescence imaging of FITC and ruthenium(II)tris-(4,7-diphenyl-1,10-phenanthroline). To create a biocompatible 2D sensor, these dyes were bound to or incorporated into microparticles (aminocellulose and polyacrylonitrile), and particles were immobilized in polyurethane hydrogel on transparent foils. We show sensor precision and validity by conducting in vitro and in vivo experiments, and we show the versatility in imaging pH during physiological and chronic cutaneous wound healing in humans. Implementation of this technique may open vistas in wound healing, tumor biology, and other biomedical fields. PMID:21262842

  3. Volume Calculation of Venous Thrombosis Using 2D Ultrasound Images.

    PubMed

    Dhibi, M; Puentes, J; Bressollette, L; Guias, B; Solaiman, B

    2005-01-01

    Venous thrombosis screening exams use 2D ultrasound images, from which medical experts obtain a rough idea of the thrombosis aspect and infer an approximate volume. Such estimation is essential to follow up the thrombosis evolution. This paper proposes a method to calculate venous thrombosis volume from non-parallel 2D ultrasound images, taking advantage of a priori knowledge about the thrombosis shape. An interactive ellipse fitting contour segmentation extracts the 2D thrombosis contours. Then, a Delaunay triangulation is applied to the set of 2D segmented contours positioned in 3D, and the area that each contour defines, to obtain a global thrombosis 3D surface reconstruction, with a dense triangulation inside the contours. Volume is calculated from the obtained surface and contours triangulation, using a maximum unit normal component approach. Preliminary results obtained on 3 plastic phantoms and 3 in vitro venous thromboses, as well as one in vivo case are presented and discussed. An error rate of volume estimation inferior to 4,5% for the plastic phantoms, and 3,5% for the in vitro venous thromboses was obtained. PMID:17281109

  4. SAR imaging via modern 2-D spectral estimation methods.

    PubMed

    DeGraaf, S R

    1998-01-01

    This paper discusses the use of modern 2D spectral estimation algorithms for synthetic aperture radar (SAR) imaging. The motivation for applying power spectrum estimation methods to SAR imaging is to improve resolution, remove sidelobe artifacts, and reduce speckle compared to what is possible with conventional Fourier transform SAR imaging techniques. This paper makes two principal contributions to the field of adaptive SAR imaging. First, it is a comprehensive comparison of 2D spectral estimation methods for SAR imaging. It provides a synopsis of the algorithms available, discusses their relative merits for SAR imaging, and illustrates their performance on simulated and collected SAR imagery. Some of the algorithms presented or their derivations are new, as are some of the insights into or analyses of the algorithms. Second, this work develops multichannel variants of four related algorithms, minimum variance method (MVM), reduced-rank MVM (RRMVM), adaptive sidelobe reduction (ASR) and space variant apodization (SVA) to estimate both reflectivity intensity and interferometric height from polarimetric displaced-aperture interferometric data. All of these interferometric variants are new. In the interferometric contest, adaptive spectral estimation can improve the height estimates through a combination of adaptive nulling and averaging. Examples illustrate that MVM, ASR, and SVA offer significant advantages over Fourier methods for estimating both scattering intensity and interferometric height, and allow empirical comparison of the accuracies of Fourier, MVM, ASR, and SVA interferometric height estimates. PMID:18276288

  5. 2D Neutron Diffraction Imaging on an Ammonite

    NASA Astrophysics Data System (ADS)

    Shamoto, Shin-ichi; Kodama, Katsuaki; Imaki, Tadashi; Nakatani, Takeshi; Oshita, Hidetoshi; Kaneko, Naokatsu; Masuko, Kenji; Sakamoto, Kensaku; Yamaguchi, Kenji; Suzuya, Kentaro; Otomo, Toshiya

    2D neutron diffraction imaging of an ammonite fossil was carried out at high-intensity total diffractometer NOVA in J-PARC. Observed diffraction profiles consist of calcite, siderite and amorphous structures. Most of part in the ammonite is calcite. The calcite image shows air chambers divided by septa in the spiral shell. Siderite is observed only in the body chamber. Amorphous structure is observed in both the protoconch and the inner whorls. Based on the crystal structures, their chemical compositions are discussed.

  6. Multifluorescence 2D gel imaging and image analysis.

    PubMed

    Vormbrock, Ingo; Hartwig, Sonja; Lehr, Stefan

    2012-01-01

    Although image acquisition and analysis are crucial steps within the multifluorescence two-dimensional gel electrophoresis workflow, some basics are frequently not carried out with the necessary diligence. This chapter should help to prevent easily avoidable failures during imaging and image preparation for comparative protein analysis. PMID:22311751

  7. Symmetries of the 2D magnetic particle imaging system matrix.

    PubMed

    Weber, A; Knopp, T

    2015-05-21

    In magnetic particle imaging (MPI), the relation between the particle distribution and the measurement signal can be described by a linear system of equations. For 1D imaging, it can be shown that the system matrix can be expressed as a product of a convolution matrix and a Chebyshev transformation matrix. For multidimensional imaging, the structure of the MPI system matrix is not yet fully explored as the sampling trajectory complicates the physical model. It has been experimentally found that the MPI system matrix rows have symmetries and look similar to the tensor products of Chebyshev polynomials. In this work we will mathematically prove that the 2D MPI system matrix has symmetries that can be used for matrix compression. PMID:25919400

  8. Image Appraisal for 2D and 3D Electromagnetic Inversion

    SciTech Connect

    Alumbaugh, D.L.; Newman, G.A.

    1999-01-28

    Linearized methods are presented for appraising image resolution and parameter accuracy in images generated with two and three dimensional non-linear electromagnetic inversion schemes. When direct matrix inversion is employed, the model resolution and posterior model covariance matrices can be directly calculated. A method to examine how the horizontal and vertical resolution varies spatially within the electromagnetic property image is developed by examining the columns of the model resolution matrix. Plotting the square root of the diagonal of the model covariance matrix yields an estimate of how errors in the inversion process such as data noise and incorrect a priori assumptions about the imaged model map into parameter error. This type of image is shown to be useful in analyzing spatial variations in the image sensitivity to the data. A method is analyzed for statistically estimating the model covariance matrix when the conjugate gradient method is employed rather than a direct inversion technique (for example in 3D inversion). A method for calculating individual columns of the model resolution matrix using the conjugate gradient method is also developed. Examples of the image analysis techniques are provided on 2D and 3D synthetic cross well EM data sets, as well as a field data set collected at the Lost Hills Oil Field in Central California.

  9. 2-D Drift Velocities from the IMAGE EUV Plasmaspheric Imager

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.

    2006-01-01

    The IMAGE Mission extreme ultraviolet imager (EW) observes He(+) plasmaspheric ions throughout the inner magnetosphere. Limited by ionizing radiation and viewing close to the Sun, images of the He(+) distribution are available every 10 minutes for many hours as the spacecraft passes through apogee in its highly elliptical orbit. As a consistent constituent at about 15%, He(+) is an excellent surrogate for monitoring all of the processes that control the dynamics of plasmaspheric plasma. In particular, the motion of He' transverse to the ambient magnetic field is a direct indication of convective electric fields. The analysis of boundary motions has already achieved new insights into the electrodynamic coupling processes taking place between energetic magnetospheric plasmas and the ionosphere. Yet to be fulfilled, however, is the original promise that global E W images of the plasmasphere might yield two-dimensional pictures of mesoscale to macro-scale electric fields in the inner magnetosphere. This work details the technique and initial application of an IMAGE EUV analysis that appears capable of following thermal plasma motion on a global basis.

  10. 2-D Drift Velocities from the IMAGE EUV Plasmaspheric Imager

    NASA Technical Reports Server (NTRS)

    Gallagher, D.; Adrian, M.

    2007-01-01

    The IMAGE Mission extreme ultraviolet imager (EUY) observes He+ plasmaspheric ions throughout the inner magnetosphere. Limited by ionizing radiation and viewing close to the Sun, images of the He+ distribution are available every 10 minutes for many hours as the spacecraft passes through apogee in its highly elliptical orbit. As a consistent constituent at about 15%, He+ is an excellent surrogate for monitoring all of the processes that control the dynamics of plasmaspheric plasma. In particular, the motion ofHe+ transverse to the ambient magnetic field is a direct indication of convective electric fields. The analysis of boundary motions has already achieved new insights into the electrodynamic coupling processes taking place between energetic magnetospheric plasmas and the ionosphere. Yet to be fulfilled, however, is the original promise that global EUY images of the plasmasphere might yield two-dimensional pictures of meso-scale to macro-scale electric fields in the inner magnetosphere. This work details the technique and initial application of an IMAGE EUY analysis that appears capable of following thermal plasma motion on a global basis.

  11. 2D magnetic nanoparticle imaging using magnetization response second harmonic

    NASA Astrophysics Data System (ADS)

    Tanaka, Saburo; Murata, Hayaki; Oishi, Tomoya; Suzuki, Toshifumi; Zhang, Yi

    2015-06-01

    A detection method and an imaging technique for magnetic nanoparticles (MNPs) have been investigated. In MNP detection and in magnetic particle imaging (MPI), the most commonly employed method is the detection of the odd harmonics of the magnetization response. We examined the advantage of using the second harmonic response when applying an AC magnetic modulation field and a DC bias field. If the magnetization response is detected by a Cu-wound-coil detection system, the output voltage from the coil is proportional to the change in the flux, dϕ/dt. Thus, the dependence of the derivative of the magnetization, M, on an AC magnetic modulation field and a DC bias field were calculated and investigated. The calculations were in good agreement with the experimental results. We demonstrated that the use of the second harmonic response for the detection of MNPs has an advantage compared with the usage of the third harmonic response, when the Cu-wound-coil detection system is employed and the amplitude of the ratio of the AC modulation field and a knee field Hac/Hk is less than 2. We also constructed a 2D MPI scanner using a pair of permanent ring magnets with a bore of ϕ80 mm separated by 90 mm. The magnets generated a gradient of Gz=3.17 T/m transverse to the imaging bore and Gx=1.33 T/m along the longitudinal axis. An original concentrated 10 μl Resovist solution in a ϕ2×3 mm2 vessel was used as a sample, and it was imaged by the scanner. As a result, a 2D contour map image could be successfully generated using the method with a lock-in amplifier.

  12. Tracking of deformable target in 2D ultrasound images

    NASA Astrophysics Data System (ADS)

    Royer, Lucas; Marchal, Maud; Le Bras, Anthony; Dardenne, Guillaume; Krupa, Alexandre

    2015-03-01

    In this paper, we propose a novel approach for automatically tracking deformable target within 2D ultrasound images. Our approach uses only dense information combined with a physically-based model and has therefore the advantage of not using any fiducial marker nor a priori knowledge on the anatomical environment. The physical model is represented by a mass-spring damper system driven by different types of forces where the external forces are obtained by maximizing image similarity metric between a reference target and a deformed target across the time. This deformation is represented by a parametric warping model where the optimal parameters are estimated from the intensity variation. This warping function is well-suited to represent localized deformations in the ultrasound images because it directly links the forces applied on each mass with the motion of all the pixels in its vicinity. The internal forces constrain the deformation to physically plausible motions, and reduce the sensitivity to the speckle noise. The approach was validated on simulated and real data, both for rigid and free-form motions of soft tissues. The results are very promising since the deformable target could be tracked with a good accuracy for both types of motion. Our approach opens novel possibilities for computer-assisted interventions where deformable organs are involved and could be used as a new tool for interactive tracking of soft tissues in ultrasound images.

  13. A scanning-mode 2D shear wave imaging (s2D-SWI) system for ultrasound elastography.

    PubMed

    Qiu, Weibao; Wang, Congzhi; Li, Yongchuan; Zhou, Juan; Yang, Ge; Xiao, Yang; Feng, Ge; Jin, Qiaofeng; Mu, Peitian; Qian, Ming; Zheng, Hairong

    2015-09-01

    Ultrasound elastography is widely used for the non-invasive measurement of tissue elasticity properties. Shear wave imaging (SWI) is a quantitative method for assessing tissue stiffness. SWI has been demonstrated to be less operator dependent than quasi-static elastography, and has the ability to acquire quantitative elasticity information in contrast with acoustic radiation force impulse (ARFI) imaging. However, traditional SWI implementations cannot acquire two dimensional (2D) quantitative images of the tissue elasticity distribution. This study proposes and evaluates a scanning-mode 2D SWI (s2D-SWI) system. The hardware and image processing algorithms are presented in detail. Programmable devices are used to support flexible control of the system and the image processing algorithms. An analytic signal based cross-correlation method and a Radon transformation based shear wave speed determination method are proposed, which can be implemented using parallel computation. Imaging of tissue mimicking phantoms, and in vitro, and in vivo imaging test are conducted to demonstrate the performance of the proposed system. The s2D-SWI system represents a new choice for the quantitative mapping of tissue elasticity, and has great potential for implementation in commercial ultrasound scanners. PMID:26025508

  14. 3D/2D image registration by image transformation descriptors (ITDs) for thoracic aorta imaging

    NASA Astrophysics Data System (ADS)

    Łubniewski, Paweł J.; Sarry, Laurent; Miguel, Bruno; Lohou, Christophe

    2013-03-01

    In this article, we present a novel image registration technique. Unlike most state of the art methods, our approach allows us to compute directly the relationship between images. The proposed registration framework, built in a modular way, can be adjusted to particular problems. Tests on sample image database of thoracic aorta proved that our method is fast and robust and could be successfully used for many cases. We have enhanced our previous works to provide a rapid 3D/2D registration method. It uses direct computing of the image transformation descriptors (ITDs) to align the projection images. The 3D transformation is estimated by an interesting technique which allows to propose a 3D pose update, interpreting the 2D transform of the projections in the 3D domain. The presented 3D/2D registration technique based on ITDs can be used as an initialization technique for classic registration algorithms. Its unique properties can be advantageous for many image alignment problems. The possibility of using different descriptors, adapted for particular cases, makes our approach very flexible. Fast time of computing is an important feature and motivates to use our technique even as an initialization step before execution of well known standard algorithms which could be more precise, but slow and sensitive to initialization of the parameters.

  15. Real-time 2D Imaging of Thermal and Mechanical Tissue Response to Focused Ultrasound

    NASA Astrophysics Data System (ADS)

    Liu, Dalong; Ebbini, Emad S.

    2010-03-01

    An integrated system capable of performing high frame-rate two-dimensional (2D) temperature imaging in realtime is has been developed. The system consists of a SonixRP ultrasound scanner and a custom built data processing unit connected with Gigabit Ethernet (GbE). The SonixRP scanner which serves as the frontend of the integrated system allows us to have flexibilities of controlling the beam sequence and accessing the radio frequency (RF) data in realtime through its research interface. The RF data is then streamlined to the backend of the system through GbE, where the data is processed using a 2D temperature estimation algorithm running in a general purpose graphics processing unit (GPU). Using this system, we have developed a 2D high frame-rate imaging mode, M2D, for imaging the mechanical and thermal tissue response to subtherapeutic HIFU beams. In this paper, we present results from imaging subtherapetic HIFU beams in vitro porcine heart before and after lesion formation. The results demonstrate the feasibility of tissue parameter changes due to HIFU-induced lesions.

  16. 2D luminescence imaging of physiological wound oxygenation.

    PubMed

    Schreml, Stephan; Meier, Robert J; Wolfbeis, Otto S; Maisch, Tim; Szeimies, Rolf-Markus; Landthaler, Michael; Regensburger, Johannes; Santarelli, Francesco; Klimant, Ingo; Babilas, Philipp

    2011-07-01

    In cutaneous wound healing, the role of oxygen in vivo is poorly understood. We studied wound surface pO(2) during physiological wound healing in humans. Split-thickness skin graft donor sites (n=12) served as standardized wound models. Wound surface pO(2) was measured at 1, 6 and 14days after split-skin harvesting using two-dimensional luminescence lifetime imaging (2D-LLI) of palladium(II)-meso-tetraphenyl-tetrabenzoporphyrin (Pd-TPTBP) in polystyrene-co-acrylonitrile (PSAN) particles on transparent foils. In another experiment, we removed the stratum corneum (SC) on the volar forearm (n=10) by tape strippings to study the impact of the SC on the epidermal oxygen barrier. Split-skin donor site pO(2) significantly decreased during the time course of physiological healing. Regional differences in pO(2) within donor site wounds were visualized for the first time in literature. No difference was found in pO(2) before and after SC removal, showing that the SC is not a major constituent of the epidermal oxygen barrier. PMID:21443617

  17. A 2-D imaging heat-flux gauge

    NASA Astrophysics Data System (ADS)

    Noel, B. W.; Borella, H. M.; Beshears, D. L.; Sartory, W. K.; Tobin, K. W.; Williams, R. K.; Turley, W. D.

    1991-07-01

    This report describes a new leadless two-dimensional imaging optical heat-flux gauge. The gauge is made by depositing arrays of thermorgraphic-phosphor (TP) spots onto the faces of a polymethylpentene insulator. In the first section of the report, we describe several gauge configurations and their prototype realizations. A satisfactory configuration is an array of right triangles on each face that overlay to form squares when the gauge is viewed normal to the surface. The next section of the report treats the thermal conductivity of TP's. We set up an experiment using a comparative longitudinal heat-flow apparatus to measure the previously unknown thermal conductivity of these materials. The thermal conductivity of one TP, Y2O3:Eu, is 0.0137 W/cm x K over the temperature range from about 300 to 360 K. The theories underlying the time response of TP gauges and the imaging characteristics are discussed in the next section. Then we discuss several laboratory experiments to: (1) demonstrate that the TP heat-flux gauge can be used in imaging applications; (2) obtain a quantum yield that enumerates what typical optical output signal amplitudes can be obtained from TP heat-flux gauges; and (3) determine whether LANL-designed intensified video cameras have sufficient sensitivity to acquire images from the heat-flux gauges. We obtained positive results from all the measurements. Throughout the text, we note limitations, areas where improvements are needed, and where further research is necessary.

  18. A 2-D imaging heat-flux gauge

    SciTech Connect

    Noel, B.W.; Borella, H.M. ); Beshears, D.L.; Sartory, W.K.; Tobin, K.W.; Williams, R.K. ); Turley, W.D. . Santa Barbara Operations)

    1991-07-01

    This report describes a new leadless two-dimensional imaging optical heat-flux gauge. The gauge is made by depositing arrays of thermorgraphic-phosphor (TP) spots onto the faces of a polymethylpentene is insulator. In the first section of the report, we describe several gauge configurations and their prototype realizations. A satisfactory configuration is an array of right triangles on each face that overlay to form squares when the gauge is viewed normal to the surface. The next section of the report treats the thermal conductivity of TPs. We set up an experiment using a comparative longitudinal heat-flow apparatus to measure the previously unknown thermal conductivity of these materials. The thermal conductivity of one TP, Y{sub 2}O{sub 3}:Eu, is 0.0137 W/cm{center dot}K over the temperature range from about 300 to 360 K. The theories underlying the time response of TP gauges and the imaging characteristics are discussed in the next section. Then we discuss several laboratory experiments to (1) demonstrate that the TP heat-flux gauge can be used in imaging applications; (2) obtain a quantum yield that enumerates what typical optical output signal amplitudes can be obtained from TP heat-flux gauges; and (3) determine whether LANL-designed intensified video cameras have sufficient sensitivity to acquire images from the heat-flux gauges. We obtained positive results from all the measurements. Throughout the text, we note limitations, areas where improvements are needed, and where further research is necessary. 12 refs., 25 figs., 4 tabs.

  19. New 2D discrete Fourier transforms in image processing

    NASA Astrophysics Data System (ADS)

    Grigoryan, Artyom M.; Agaian, Sos S.

    2015-03-01

    In this paper, the concept of the two-dimensional discrete Fourier transformation (2-D DFT) is defined in the general case, when the form of relation between the spatial-points (x, y) and frequency-points (ω1, ω2) is defined in the exponential kernel of the transformation by a nonlinear form L(x, y; ω1, ω2). The traditional concept of the 2-D DFT uses the Diaphanous form xω1 +yω2 and this 2-D DFT is the particular case of the Fourier transform described by the form L(x, y; ω1, ω2). Properties of the general 2-D discrete Fourier transform are described and examples are given. The special case of the N × N-point 2-D Fourier transforms, when N = 2r, r > 1, is analyzed and effective representation of these transforms is proposed. The proposed concept of nonlinear forms can be also applied for other transformations such as Hartley, Hadamard, and cosine transformations.

  20. 2-D Temperature Measurements of the Divertor Using the Line-to-continuum Ratio Method

    NASA Astrophysics Data System (ADS)

    Boswell, C. J.; Terry, J. L.; Lipschultz, B.

    2000-10-01

    Alcator C-Mod currently employs a tangentially viewing divertor TV system consisting of two CCD cameras with nearly identical views. The cameras are filtered, typically for D_γ and CII lines (≈ 515 nm). The recorded images are inverted assuming toroidal symmetry, yielding 2-D emissivity profiles. Due to the low level of carbon after boronization the emission detected by the camera filtered for the CII lines is dominated by continuum radiation. With the 2-D profiles of D_γ and continuum emission, effective temperature measurements are obtained using the line-to-continuum ratio method,(Hans R. Griem, \\underlinePrinciples of Plasma Spectroscopy), (Cambridge University Press, New York, 1997), p. 291. which assumes that the continuum is due to ion-electron bremsstrahlung and radiative recombination only. However, additional continuum radiation has been observed previously in the divertor region.(J. L. Terry et al.), in \\underlineProc. of the 26th Euro. Phys. Soc. Conf. on \\underlineContr. Fus. and Plasma Phys., edited by B. Schweer, G. Van Oost, and E. Vietzke (Institute of Physics, London, UK 1999), pp. 325-328. 2-D plots of D_γ, continuum, and effective temperature will be presented.

  1. Screening and transport in 2D semiconductor systems at low temperatures

    PubMed Central

    Das Sarma, S.; Hwang, E. H.

    2015-01-01

    Low temperature carrier transport properties in 2D semiconductor systems can be theoretically well-understood within RPA-Boltzmann theory as being limited by scattering from screened Coulomb disorder arising from random quenched charged impurities in the environment. In this work, we derive a number of analytical formula, supported by realistic numerical calculations, for the relevant density, mobility, and temperature range where 2D transport should manifest strong intrinsic (i.e., arising purely from electronic effects) metallic temperature dependence in different semiconductor materials arising entirely from the 2D screening properties, thus providing an explanation for why the strong temperature dependence of the 2D resistivity can only be observed in high-quality and low-disorder 2D samples and also why some high-quality 2D materials manifest much weaker metallicity than other materials. We also discuss effects of interaction and disorder on the 2D screening properties in this context as well as compare 2D and 3D screening functions to comment why such a strong intrinsic temperature dependence arising from screening cannot occur in 3D metallic carrier transport. Experimentally verifiable predictions are made about the quantitative magnitude of the maximum possible low-temperature metallicity in 2D systems and the scaling behavior of the temperature scale controlling the quantum to classical crossover. PMID:26572738

  2. A Nonrigid Kernel-Based Framework for 2D-3D Pose Estimation and 2D Image Segmentation

    PubMed Central

    Sandhu, Romeil; Dambreville, Samuel; Yezzi, Anthony; Tannenbaum, Allen

    2013-01-01

    In this work, we present a nonrigid approach to jointly solving the tasks of 2D-3D pose estimation and 2D image segmentation. In general, most frameworks that couple both pose estimation and segmentation assume that one has exact knowledge of the 3D object. However, under nonideal conditions, this assumption may be violated if only a general class to which a given shape belongs is given (e.g., cars, boats, or planes). Thus, we propose to solve the 2D-3D pose estimation and 2D image segmentation via nonlinear manifold learning of 3D embedded shapes for a general class of objects or deformations for which one may not be able to associate a skeleton model. Thus, the novelty of our method is threefold: First, we present and derive a gradient flow for the task of nonrigid pose estimation and segmentation. Second, due to the possible nonlinear structures of one’s training set, we evolve the preimage obtained through kernel PCA for the task of shape analysis. Third, we show that the derivation for shape weights is general. This allows us to use various kernels, as well as other statistical learning methodologies, with only minimal changes needing to be made to the overall shape evolution scheme. In contrast with other techniques, we approach the nonrigid problem, which is an infinite-dimensional task, with a finite-dimensional optimization scheme. More importantly, we do not explicitly need to know the interaction between various shapes such as that needed for skeleton models as this is done implicitly through shape learning. We provide experimental results on several challenging pose estimation and segmentation scenarios. PMID:20733218

  3. Image-based RSA: Roentgen stereophotogrammetric analysis based on 2D-3D image registration.

    PubMed

    de Bruin, P W; Kaptein, B L; Stoel, B C; Reiber, J H C; Rozing, P M; Valstar, E R

    2008-01-01

    Image-based Roentgen stereophotogrammetric analysis (IBRSA) integrates 2D-3D image registration and conventional RSA. Instead of radiopaque RSA bone markers, IBRSA uses 3D CT data, from which digitally reconstructed radiographs (DRRs) are generated. Using 2D-3D image registration, the 3D pose of the CT is iteratively adjusted such that the generated DRRs resemble the 2D RSA images as closely as possible, according to an image matching metric. Effectively, by registering all 2D follow-up moments to the same 3D CT, the CT volume functions as common ground. In two experiments, using RSA and using a micromanipulator as gold standard, IBRSA has been validated on cadaveric and sawbone scapula radiographs, and good matching results have been achieved. The accuracy was: |mu |< 0.083 mm for translations and |mu| < 0.023 degrees for rotations. The precision sigma in x-, y-, and z-direction was 0.090, 0.077, and 0.220 mm for translations and 0.155 degrees , 0.243 degrees , and 0.074 degrees for rotations. Our results show that the accuracy and precision of in vitro IBRSA, performed under ideal laboratory conditions, are lower than in vitro standard RSA but higher than in vivo standard RSA. Because IBRSA does not require radiopaque markers, it adds functionality to the RSA method by opening new directions and possibilities for research, such as dynamic analyses using fluoroscopy on subjects without markers and computer navigation applications. PMID:17706656

  4. Antenna-coupled microbolometer based uncooled 2D array and camera for 2D real-time terahertz imaging

    NASA Astrophysics Data System (ADS)

    Simoens, F.; Meilhan, J.; Gidon, S.; Lasfargues, G.; Lalanne Dera, J.; Ouvrier-Buffet, J. L.; Pocas, S.; Rabaud, W.; Guellec, F.; Dupont, B.; Martin, S.; Simon, A. C.

    2013-09-01

    CEA-Leti has developed a monolithic large focal plane array bolometric technology optimized for 2D real-time imaging in the terahertz range. Each pixel consists in a silicon microbolometer coupled to specific antennas and a resonant quarter-wavelength cavity. First prototypes of imaging arrays have been designed and manufactured for optimized sensing in the 1-3.5THz range where THz quantum cascade lasers are delivering high optical power. NEP in the order of 1 pW/sqrt(Hz) has been assessed at 2.5 THz. This paper reports the steps of this development, starting from the pixel level, to an array associated monolithically to its CMOS ROIC and finally a stand-alone camera. For each step, modeling, technological prototyping and experimental characterizations are presented.

  5. Development of ultra-fast 2D ion Doppler tomography using image intensified CMOS fast camera

    NASA Astrophysics Data System (ADS)

    Tanabe, Hiroshi; Kuwahata, Akihiro; Yamanaka, Haruki; Inomoto, Michiaki; Ono, Yasushi; TS-group Team

    2015-11-01

    The world fastest novel time-resolved 2D ion Doppler tomography diagnostics has been developed using fast camera with high-speed gated image intensifier (frame rate: 200kfps. phosphor decay time: ~ 1 μ s). Time evolution of line-integrated spectra are diffracted from a f=1m, F/8.3 and g=2400L/mm Czerny-Turner polychromator, whose output is intensified and recorded to a high-speed camera with spectral resolution of ~0.005nm/pixel. The system can accommodate up to 36 (9 ×4) spatial points recorded at 5 μs time resolution, tomographic reconstruction is applied for the line-integrated spectra, time-resolved (5 μs/frame) local 2D ion temperature measurement has been achieved without any assumption of shot repeatability. Ion heating during intermittent reconnection event which tends to happen during high guide field merging tokamak was measured around diffusion region in UTST. The measured 2D profile shows ion heating inside the acceleration channel of reconnection outflow jet, stagnation point and downstream region where reconnected field forms thick closed flux surface as in MAST. Achieved maximum ion temperature increases as a function of Brec2 and shows good fit with MAST experiment, demonstrating promising CS-less startup scenario for spherical tokamak. This work is supported by JSPS KAKENHI Grant Number 15H05750 and 15K20921.

  6. 2D Images Recorded With a Single-Sided Magnetic Particle Imaging Scanner.

    PubMed

    Grafe, Ksenija; von Gladiss, Anselm; Bringout, Gael; Ahlborg, Mandy; Buzug, Thorsten M

    2016-04-01

    Magnetic Particle Imaging is a new medical imaging modality, which detects superparamagnetic iron oxide nanoparticles. The particles are excited by magnetic fields. Most scanners have a tube-like measurement field and therefore, both the field of view and the object size are limited. A single-sided scanner has the advantage that the object is not limited in size, only the penetration depth is limited. A single-sided scanner prototype for 1D imaging has been presented in 2009. Simulations have been published for a 2D single-sided scanner and first 1D measurements have been carried out. In this paper, the first 2D single-sided scanner prototype is presented and the first calibration-based reconstruction results of measured 2D phantoms are shown. The field free point is moved on a Lissajous trajectory inside a 30 ×30 mm(2) area. Images of phantoms with a maximal distance of 10 mm perpendicular to the scanner surface have been reconstructed. Different cylindrically shaped holes of phantoms have been filled with 6.28 μl undiluted Resovist. After the measurement and image reconstruction of the phantoms, particle volumes could be distinguished with a distance of 2 mm and 6 mm in vertical and horizontal direction, respectively. PMID:26701178

  7. Image appraisal for 2D and 3D electromagnetic inversion

    SciTech Connect

    Alumbaugh, D.L.; Newman, G.A.

    1998-04-01

    Linearized methods are presented for appraising image resolution and parameter accuracy in images generated with two and three dimensional non-linear electromagnetic inversion schemes. When direct matrix inversion is employed, the model resolution and model covariance matrices can be directly calculated. The columns of the model resolution matrix are shown to yield empirical estimates of the horizontal and vertical resolution throughout the imaging region. Plotting the square root of the diagonal of the model covariance matrix yields an estimate of how the estimated data noise maps into parameter error. When the conjugate gradient method is employed rather than a direct inversion technique (for example in 3D inversion), an iterative method can be applied to statistically estimate the model covariance matrix, as well as a regularization covariance matrix. The latter estimates the error in the inverted results caused by small variations in the regularization parameter. A method for calculating individual columns of the model resolution matrix using the conjugate gradient method is also developed. Examples of the image analysis techniques are provided on a synthetic cross well EM data set.

  8. Multifractal analysis of 2D gray soil images

    NASA Astrophysics Data System (ADS)

    González-Torres, Ivan; Losada, Juan Carlos; Heck, Richard; Tarquis, Ana M.

    2015-04-01

    Soil structure, understood as the spatial arrangement of soil pores, is one of the key factors in soil modelling processes. Geometric properties of individual and interpretation of the morphological parameters of pores can be estimated from thin sections or 3D Computed Tomography images (Tarquis et al., 2003), but there is no satisfactory method to binarized these images and quantify the complexity of their spatial arrangement (Tarquis et al., 2008, Tarquis et al., 2009; Baveye et al., 2010). The objective of this work was to apply a multifractal technique, their singularities (α) and f(α) spectra, to quantify it without applying any threshold (Gónzalez-Torres, 2014). Intact soil samples were collected from four horizons of an Argisol, formed on the Tertiary Barreiras group of formations in Pernambuco state, Brazil (Itapirema Experimental Station). The natural vegetation of the region is tropical, coastal rainforest. From each horizon, showing different porosities and spatial arrangements, three adjacent samples were taken having a set of twelve samples. The intact soil samples were imaged using an EVS (now GE Medical. London, Canada) MS-8 MicroCT scanner with 45 μm pixel-1 resolution (256x256 pixels). Though some samples required paring to fit the 64 mm diameter imaging tubes, field orientation was maintained. References Baveye, P.C., M. Laba, W. Otten, L. Bouckaert, P. Dello, R.R. Goswami, D. Grinev, A. Houston, Yaoping Hu, Jianli Liu, S. Mooney, R. Pajor, S. Sleutel, A. Tarquis, Wei Wang, Qiao Wei, Mehmet Sezgin. Observer-dependent variability of the thresholding step in the quantitative analysis of soil images and X-ray microtomography data. Geoderma, 157, 51-63, 2010. González-Torres, Iván. Theory and application of multifractal analysis methods in images for the study of soil structure. Master thesis, UPM, 2014. Tarquis, A.M., R.J. Heck, J.B. Grau; J. Fabregat, M.E. Sanchez and J.M. Antón. Influence of Thresholding in Mass and Entropy Dimension of 3-D Soil Images. Nonlinear Process in Geophysics, 15, 881-891, 2008. Tarquis, A.M., R.J. Heck, D. Andina, A. Alvarez and J.M. Antón. Multifractal analysis and thresholding of 3D soil images. Ecological Complexity, 6, 230-239, 2009. Tarquis, A.M.; D. Giménez, A. Saa, M.C. Díaz. and J.M. Gascó. Scaling and Multiscaling of Soil Pore Systems Determined by Image Analysis. Scaling Methods in Soil Systems. Pachepsky, Radcliffe and Selim Eds., 19-33, 2003. CRC Press, Boca Ratón, Florida. Acknowledgements First author acknowledges the financial support obtained from Soil Imaging Laboratory (University of Gueplh, Canada) in 2014.

  9. 2-D image segmentation using minimum spanning trees

    SciTech Connect

    Xu, Y.; Uberbacher, E.C.

    1995-09-01

    This paper presents a new algorithm for partitioning a gray-level image into connected homogeneous regions. The novelty of this algorithm lies in the fact that by constructing a minimum spanning tree representation of a gray-level image, it reduces a region partitioning problem to a minimum spanning tree partitioning problem, and hence reduces the computational complexity of the region partitioning problem. The tree-partitioning algorithm, in essence, partitions a minimum spanning tree into subtrees, representing different homogeneous regions, by minimizing the sum of variations of gray levels over all subtrees under the constraints that each subtree should have at least a specified number of nodes, and two adjacent subtrees should have significantly different average gray-levels. Two (faster) heuristic implementations are also given for large-scale region partitioning problems. Test results have shown that the segmentation results are satisfactory and insensitive to noise.

  10. Imaging 2D optical diffuse reflectance in skeletal muscle

    NASA Astrophysics Data System (ADS)

    Ranasinghesagara, Janaka; Yao, Gang

    2007-04-01

    We discovered a unique pattern of optical reflectance from fresh prerigor skeletal muscles, which can not be described using existing theories. A numerical fitting function was developed to quantify the equiintensity contours of acquired reflectance images. Using this model, we studied the changes of reflectance profile during stretching and rigor process. We found that the prominent anisotropic features diminished after rigor completion. These results suggested that muscle sarcomere structures played important roles in modulating light propagation in whole muscle. When incorporating the sarcomere diffraction in a Monte Carlo model, we showed that the resulting reflectance profiles quantitatively resembled the experimental observation.

  11. Imaging Excited State Dynamics with 2d Electronic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Engel, Gregory S.

    2012-06-01

    Excited states in the condensed phase have extremely high chemical potentials making them highly reactive and difficult to control. Yet in biology, excited state dynamics operate with exquisite precision driving solar light harvesting in photosynthetic complexes though excitonic transport and photochemistry through non-radiative relaxation to photochemical products. Optimized by evolution, these biological systems display manifestly quantum mechanical behaviors including coherent energy transfer, steering wavepacket trajectories through conical intersections and protection of long-lived quantum coherence. To image the underlying excited state dynamics, we have developed a new spectroscopic method allowing us to capture excitonic structure in real time. Through this method and other ultrafast multidimensional spectroscopies, we have captured coherent dynamics within photosynthetic antenna complexes. The data not only reveal how biological systems operate, but these same spectral signatures can be exploited to create new spectroscopic tools to elucidate the underlying Hamiltonian. New data on the role of the protein in photosynthetic systems indicates that the chromophores mix strongly with some bath modes within the system. The implications of this mixing for excitonic transport will be discussed along with prospects for transferring underlying design principles to synthetic systems.

  12. Imaging 2-D Structures With Receiver Functions Using Harmonic Stripping

    NASA Astrophysics Data System (ADS)

    Schulte-Pelkum, V.

    2010-12-01

    I present a novel technique to image dipping and anisotropic structures using receiver functions. Receiver functions isolate phase conversions from interfaces close to the seismic station. Standard analysis assumes a quasi-flat layered structure and dampens arrivals from dipping interfaces and anisotropic layers, with attempts to extract information on such structures relying on cumbersome and nonunique forward modeling. I use a simple relationship between the radial and transverse component receiver function to detect dipping and anisotropic layers and map their depth and orientation. For dipping interfaces, layers with horizontal or plunging axis anisotropy, and point scatterers, the following relationships hold: After subtracting the azimuthally invariant portion of the radial receiver functions, the remaining signal is an azimuthally shifted version of the transverse receiver functions. The strike of the dipping interface or anisotropy is given by the azimuth of polarity reversals, and the type of structure can be inferred from the amount of phase shift between the components. For a known structure type, the phase shift between the two components provides pseudoevents from back-azimuths with little seismicity. The technique allows structural mapping at depth akin to geological mapping of rock fabric and dipping layers at the surface. It reduces complex wavefield effects to two simple and geologically meaningful parameters, similar to shear wave splitting. I demonstrate the method on the Wind River Thrust as well as other structures within the Transportable Array footprint.

  13. Fast Confocal Raman Imaging Using a 2-D Multifocal Array for Parallel Hyperspectral Detection.

    PubMed

    Kong, Lingbo; Navas-Moreno, Maria; Chan, James W

    2016-01-19

    We present the development of a novel confocal hyperspectral Raman microscope capable of imaging at speeds up to 100 times faster than conventional point-scan Raman microscopy under high noise conditions. The microscope utilizes scanning galvomirrors to generate a two-dimensional (2-D) multifocal array at the sample plane, generating Raman signals simultaneously at each focus of the array pattern. The signals are combined into a single beam and delivered through a confocal pinhole before being focused through the slit of a spectrometer. To separate the signals from each row of the array, a synchronized scan mirror placed in front of the spectrometer slit positions the Raman signals onto different pixel rows of the detector. We devised an approach to deconvolve the superimposed signals and retrieve the individual spectra at each focal position within a given row. The galvomirrors were programmed to scan different focal arrays following Hadamard encoding patterns. A key feature of the Hadamard detection is the reconstruction of individual spectra with improved signal-to-noise ratio. Using polystyrene beads as test samples, we demonstrated not only that our system images faster than a conventional point-scan method but that it is especially advantageous under noisy conditions, such as when the CCD detector operates at fast read-out rates and high temperatures. This is the first demonstration of multifocal confocal Raman imaging in which parallel spectral detection is implemented along both axes of the CCD detector chip. We envision this novel 2-D multifocal spectral detection technique can be used to develop faster imaging spontaneous Raman microscopes with lower cost detectors. PMID:26654100

  14. 3-D Reconstruction From 2-D Radiographic Images and Its Application to Clinical Veterinary Medicine

    NASA Astrophysics Data System (ADS)

    Hamamoto, Kazuhiko; Sato, Motoyoshi

    3D imaging technique is very important and indispensable in diagnosis. The main stream of the technique is one in which 3D image is reconstructed from a set of slice images, such as X-ray CT and MRI. However, these systems require large space and high costs. On the other hand, a low cost and small size 3D imaging system is needed in clinical veterinary medicine, for example, in the case of diagnosis in X-ray car or pasture area. We propose a novel 3D imaging technique using 2-D X-ray radiographic images. This system can be realized by cheaper system than X-ray CT and enables to get 3D image in X-ray car or portable X-ray equipment. In this paper, a 3D visualization technique from 2-D radiographic images is proposed and several reconstructions are shown. These reconstructions are evaluated by veterinarians.

  15. A new gold-standard dataset for 2D/3D image registration evaluation

    NASA Astrophysics Data System (ADS)

    Pawiro, Supriyanto; Markelj, Primoz; Gendrin, Christelle; Figl, Michael; Stock, Markus; Bloch, Christoph; Weber, Christoph; Unger, Ewald; Nöbauer, Iris; Kainberger, Franz; Bergmeister, Helga; Georg, Dietmar; Bergmann, Helmar; Birkfellner, Wolfgang

    2010-02-01

    In this paper, we propose a new gold standard data set for the validation of 2D/3D image registration algorithms for image guided radiotherapy. A gold standard data set was calculated using a pig head with attached fiducial markers. We used several imaging modalities common in diagnostic imaging or radiotherapy which include 64-slice computed tomography (CT), magnetic resonance imaging (MRI) using T1, T2 and proton density (PD) sequences, and cone beam CT (CBCT) imaging data. Radiographic data were acquired using kilovoltage (kV) and megavoltage (MV) imaging techniques. The image information reflects both anatomy and reliable fiducial marker information, and improves over existing data sets by the level of anatomical detail and image data quality. The markers of three dimensional (3D) and two dimensional (2D) images were segmented using Analyze 9.0 (AnalyzeDirect, Inc) and an in-house software. The projection distance errors (PDE) and the expected target registration errors (TRE) over all the image data sets were found to be less than 1.7 mm and 1.3 mm, respectively. The gold standard data set, obtained with state-of-the-art imaging technology, has the potential to improve the validation of 2D/3D registration algorithms for image guided therapy.

  16. Wall surface temperature calculation in the SolEdge2D-EIRENE transport code

    NASA Astrophysics Data System (ADS)

    Denis, J.; Pégourié, B.; Bucalossi, J.; Bufferand, H.; Ciraolo, G.; Gardarein, J.-L.; Gaspar, J.; Grisolia, C.; Hodille, E.; Missirlian, M.; Serre, E.; Tamain, P.

    2016-02-01

    A thermal wall model is developed for the SolEdge2D-EIRENE edge transport code for calculating the surface temperature of the actively-cooled vessel components in interaction with the plasma. This is a first step towards a self-consistent evaluation of the recycling of particles, which depends on the wall surface temperature. The proposed thermal model is built to match both steady-state temperature and time constant of actively-cooled plasma facing components. A benchmark between this model and the Finite Element Modelling code CAST3M is performed in the case of an ITER-like monoblock. An example of application is presented for a SolEdge2D-EIRENE simulation of a medium-power discharge in the WEST tokamak, showing the steady-state wall temperature distribution and the temperature cycling due to an imposed Edge Localised Mode-like event.

  17. 3D-2D Deformable Image Registration Using Feature-Based Nonuniform Meshes.

    PubMed

    Zhong, Zichun; Guo, Xiaohu; Cai, Yiqi; Yang, Yin; Wang, Jing; Jia, Xun; Mao, Weihua

    2016-01-01

    By using prior information of planning CT images and feature-based nonuniform meshes, this paper demonstrates that volumetric images can be efficiently registered with a very small portion of 2D projection images of a Cone-Beam Computed Tomography (CBCT) scan. After a density field is computed based on the extracted feature edges from planning CT images, nonuniform tetrahedral meshes will be automatically generated to better characterize the image features according to the density field; that is, finer meshes are generated for features. The displacement vector fields (DVFs) are specified at the mesh vertices to drive the deformation of original CT images. Digitally reconstructed radiographs (DRRs) of the deformed anatomy are generated and compared with corresponding 2D projections. DVFs are optimized to minimize the objective function including differences between DRRs and projections and the regularity. To further accelerate the above 3D-2D registration, a procedure to obtain good initial deformations by deforming the volume surface to match 2D body boundary on projections has been developed. This complete method is evaluated quantitatively by using several digital phantoms and data from head and neck cancer patients. The feature-based nonuniform meshing method leads to better results than either uniform orthogonal grid or uniform tetrahedral meshes. PMID:27019849

  18. 3D-2D Deformable Image Registration Using Feature-Based Nonuniform Meshes

    PubMed Central

    Guo, Xiaohu; Cai, Yiqi; Yang, Yin; Wang, Jing; Jia, Xun

    2016-01-01

    By using prior information of planning CT images and feature-based nonuniform meshes, this paper demonstrates that volumetric images can be efficiently registered with a very small portion of 2D projection images of a Cone-Beam Computed Tomography (CBCT) scan. After a density field is computed based on the extracted feature edges from planning CT images, nonuniform tetrahedral meshes will be automatically generated to better characterize the image features according to the density field; that is, finer meshes are generated for features. The displacement vector fields (DVFs) are specified at the mesh vertices to drive the deformation of original CT images. Digitally reconstructed radiographs (DRRs) of the deformed anatomy are generated and compared with corresponding 2D projections. DVFs are optimized to minimize the objective function including differences between DRRs and projections and the regularity. To further accelerate the above 3D-2D registration, a procedure to obtain good initial deformations by deforming the volume surface to match 2D body boundary on projections has been developed. This complete method is evaluated quantitatively by using several digital phantoms and data from head and neck cancer patients. The feature-based nonuniform meshing method leads to better results than either uniform orthogonal grid or uniform tetrahedral meshes. PMID:27019849

  19. A 2-D dynamical model of mesospheric temperature inversions in winter

    SciTech Connect

    Hauchecorne, A.; Maillard, A. )

    1990-11-01

    A 2-D stratospheric and mesospheric dynamical model including drag and diffusion due to gravity wave breaking is used to simulate winter mesospheric temperature inversions similar to those observed by Rayleigh lidar. It is shown that adiabatic heating associated to descending velocities in the mesosphere is the main mechanism involved in the formation of such inversions. Sensitivity tests are performed with the model and confirm this assumption. It is also explained why other previous similar studies with 2-D models did not show mesospheric inversion layers.

  20. Talbot images and Talbot spectra of a 2D orthogonal periodicity structure

    NASA Astrophysics Data System (ADS)

    Han, Pin; Weng, Junhong

    2016-05-01

    The conditions for Talbot images and Talbot spectra associated with a 2D orthogonal periodicity structure are obtained with the transfer function method. It is found that the longitudinal distances to find the whole 2D Talbot images are the least common multiple of each of the individual 1D Talbot periodicities. Also, the transversal locations to find the Talbot spectra are given, where the detected spectra are identical to the incident one without the effect of diffraction. The spectral switches involved are also presented.

  1. Nanohole-array-based device for 2D snapshot multispectral imaging

    PubMed Central

    Najiminaini, Mohamadreza; Vasefi, Fartash; Kaminska, Bozena; Carson, Jeffrey J. L.

    2013-01-01

    We present a two-dimensional (2D) snapshot multispectral imager that utilizes the optical transmission characteristics of nanohole arrays (NHAs) in a gold film to resolve a mixture of input colors into multiple spectral bands. The multispectral device consists of blocks of NHAs, wherein each NHA has a unique periodicity that results in transmission resonances and minima in the visible and near-infrared regions. The multispectral device was illuminated over a wide spectral range, and the transmission was spectrally unmixed using a least-squares estimation algorithm. A NHA-based multispectral imaging system was built and tested in both reflection and transmission modes. The NHA-based multispectral imager was capable of extracting 2D multispectral images representative of four independent bands within the spectral range of 662?nm to 832?nm for a variety of targets. The multispectral device can potentially be integrated into a variety of imaging sensor systems. PMID:24005065

  2. Gated cardiac NMR imaging and 2D echocardiography in the detection of intracardial neoplasm

    SciTech Connect

    Go, R.T.; O'Donnell, J.K.; Salcedo, E.E.; Feiglin, D.H.; Underwood, D.A.; MacIntyre, W.J.; Meaney, T.F.

    1985-05-01

    Noninvasive 2D echocardiography has replaced contrast angiography as the procedure of choice in the diagnosis of intracardiac neoplasm. The purpose of this study was to determine whether intracardiac neoplasm can be detected as well by gated cardiac NMR. Four patients with known intracardiac neoplasm previously diagnosed by 2D echocardiography had gated cardiac NMR imaging using a superconductive 0.6 Tesla magnet. All patients were performed using a Tl weighted spin echo pulse sequence with a TE of 30 msec and TR of one R-R interval. Two-dimensional planar single or multiple slice techniques were used. In one patient, imaging at different times along the R-R interval were performed for cine display. The results of the present study show detection of the intracardiac neoplasm in all four cases by gated cardiac NMR imaging and the results were comparable to 2D echocardiography. The former imaging technique showed superior spatial resolution. Despite its early stage of development, gated cardiac NMR imaging appears at least equal to 2D echocardiography in the detection of intracardiac neoplasm. The availability of multislice coupled with multiframe acquisition techniques now being developed will provide a cinematic display that will be more effective in the display of the tumor in motion within the cardiac chamber involved and facilitate visualization of the relationship of the tumor to adjacent cardiac structures.

  3. Tensor representation of color images and fast 2D quaternion discrete Fourier transform

    NASA Astrophysics Data System (ADS)

    Grigoryan, Artyom M.; Agaian, Sos S.

    2015-03-01

    In this paper, a general, efficient, split algorithm to compute the two-dimensional quaternion discrete Fourier transform (2-D QDFT), by using the special partitioning in the frequency domain, is introduced. The partition determines an effective transformation, or color image representation in the form of 1-D quaternion signals which allow for splitting the N × M-point 2-D QDFT into a set of 1-D QDFTs. Comparative estimates revealing the efficiency of the proposed algorithms with respect to the known ones are given. In particular, a proposed method of calculating the 2r × 2r -point 2-D QDFT uses 18N2 less multiplications than the well-known column-row method and method of calculation based on the symplectic decomposition. The proposed algorithm is simple to apply and design, which makes it very practical in color image processing in the frequency domain.

  4. Parameterising root system growth models using 2D neutron radiography images

    NASA Astrophysics Data System (ADS)

    Schnepf, Andrea; Felderer, Bernd; Vontobel, Peter; Leitner, Daniel

    2013-04-01

    Root architecture is a key factor for plant acquisition of water and nutrients from soil. In particular in view of a second green revolution where the below ground parts of agricultural crops are important, it is essential to characterise and quantify root architecture and its effect on plant resource acquisition. Mathematical models can help to understand the processes occurring in the soil-plant system, they can be used to quantify the effect of root and rhizosphere traits on resource acquisition and the response to environmental conditions. In order to do so, root architectural models are coupled with a model of water and solute transport in soil. However, dynamic root architectural models are difficult to parameterise. Novel imaging techniques such as x-ray computed tomography, neutron radiography and magnetic resonance imaging enable the in situ visualisation of plant root systems. Therefore, these images facilitate the parameterisation of dynamic root architecture models. These imaging techniques are capable of producing 3D or 2D images. Moreover, 2D images are also available in the form of hand drawings or from images of standard cameras. While full 3D imaging tools are still limited in resolutions, 2D techniques are a more accurate and less expensive option for observing roots in their environment. However, analysis of 2D images has additional difficulties compared to the 3D case, because of overlapping roots. We present a novel algorithm for the parameterisation of root system growth models based on 2D images of root system. The algorithm analyses dynamic image data. These are a series of 2D images of the root system at different points in time. Image data has already been adjusted for missing links and artefacts and segmentation was performed by applying a matched filter response. From this time series of binary 2D images, we parameterise the dynamic root architecture model in the following way: First, a morphological skeleton is derived from the binary images by a closing and a thinning step. Then, a weighted graph is produced from this skeleton, where root tips and branch points are the nodes of the graph. For each connecting edge, the pixel coordinates are stored in a list. Finally, a root system growth model is used to determine individual roots within the graph. In this way, the sequential appearance of each sub-branch is maintained. We demonstrate the use of this algorithm to determine parameters for the root system growth model of Leitner et al. (2010). We use 2D radiography images of Lupine plants. Parameters that are gained from the images include the length of the apical and basal zones, the internodal distances, the number of branches per root, the branching angels, the root radii, and the root growth rate. Computed parameter values are means of four replicates, i.e. the means over four root systems grown under the same conditions. The root systems were classified according to their branching order, and average parameter values were determined for each root order. Based on these parameters, the dynamics of root system growth can be recaptured and analysed.

  5. The 2D analytic signal for envelope detection and feature extraction on ultrasound images.

    PubMed

    Wachinger, Christian; Klein, Tassilo; Navab, Nassir

    2012-08-01

    The fundamental property of the analytic signal is the split of identity, meaning the separation of qualitative and quantitative information in form of the local phase and the local amplitude, respectively. Especially the structural representation, independent of brightness and contrast, of the local phase is interesting for numerous image processing tasks. Recently, the extension of the analytic signal from 1D to 2D, covering also intrinsic 2D structures, was proposed. We show the advantages of this improved concept on ultrasound RF and B-mode images. Precisely, we use the 2D analytic signal for the envelope detection of RF data. This leads to advantages for the extraction of the information-bearing signal from the modulated carrier wave. We illustrate this, first, by visual assessment of the images, and second, by performing goodness-of-fit tests to a Nakagami distribution, indicating a clear improvement of statistical properties. The evaluation is performed for multiple window sizes and parameter estimation techniques. Finally, we show that the 2D analytic signal allows for an improved estimation of local features on B-mode images. PMID:22704027

  6. 2D imaging and 3D sensing data acquisition and mutual registration for painting conservation

    NASA Astrophysics Data System (ADS)

    Fontana, Raffaella; Gambino, Maria Chiara; Greco, Marinella; Marras, Luciano; Pampaloni, Enrico M.; Pelagotti, Anna; Pezzati, Luca; Poggi, Pasquale

    2004-12-01

    We describe the application of 2D and 3D data acquisition and mutual registration to the conservation of paintings. RGB color image acquisition, IR and UV fluorescence imaging, together with the more recent hyperspectral imaging (32 bands) are among the most useful techniques in this field. They generally are meant to provide information on the painting materials, on the employed techniques and on the object state of conservation. However, only when the various images are perfectly registered on each other and on the 3D model, no ambiguity is possible and safe conclusions may be drawn. We present the integration of 2D and 3D measurements carried out on two different paintings: "Madonna of the Yarnwinder" by Leonardo da Vinci, and "Portrait of Lionello d'Este", by Pisanello, both painted in the XV century.

  7. 2D imaging and 3D sensing data acquisition and mutual registration for painting conservation

    NASA Astrophysics Data System (ADS)

    Fontana, Raffaella; Gambino, Maria Chiara; Greco, Marinella; Marras, Luciano; Pampaloni, Enrico M.; Pelagotti, Anna; Pezzati, Luca; Poggi, Pasquale

    2005-01-01

    We describe the application of 2D and 3D data acquisition and mutual registration to the conservation of paintings. RGB color image acquisition, IR and UV fluorescence imaging, together with the more recent hyperspectral imaging (32 bands) are among the most useful techniques in this field. They generally are meant to provide information on the painting materials, on the employed techniques and on the object state of conservation. However, only when the various images are perfectly registered on each other and on the 3D model, no ambiguity is possible and safe conclusions may be drawn. We present the integration of 2D and 3D measurements carried out on two different paintings: "Madonna of the Yarnwinder" by Leonardo da Vinci, and "Portrait of Lionello d'Este", by Pisanello, both painted in the XV century.

  8. Operator guidance in 2D echocardiography via 3D model to image registration

    NASA Astrophysics Data System (ADS)

    Bergmeir, Christoph; Subramanian, Navneeth

    2009-02-01

    Ubiquitous use of 2D ultrasound (US) is limited by the difficulty in interpretation of images for an untrained operator. We present a solution for operator guidance through visual cues via registration of US to a 3D model. The method is demonstrated on 2D echocardiography data, where we are able to localize the scan plane in relation to the standard planes on the 3D model. Our algorithm operates by pre-processing both the US and CT images to the most basic information- muscle, blood pool - using classification. Subsequently, these labels are registered using the match cardinality metric for binary labeled images. We evaluated our method on four parasternal long-axis and three parasternal short-axis images from different patients. Results show that our system is able to correctly distinguish between the different US standard views and is able to localize the scan on the 3D model, correctly on five out of seven cases.

  9. Combining 2D synchrosqueezed wave packet transform with optimization for crystal image analysis

    NASA Astrophysics Data System (ADS)

    Lu, Jianfeng; Wirth, Benedikt; Yang, Haizhao

    2016-04-01

    We develop a variational optimization method for crystal analysis in atomic resolution images, which uses information from a 2D synchrosqueezed transform (SST) as input. The synchrosqueezed transform is applied to extract initial information from atomic crystal images: crystal defects, rotations and the gradient of elastic deformation. The deformation gradient estimate is then improved outside the identified defect region via a variational approach, to obtain more robust results agreeing better with the physical constraints. The variational model is optimized by a nonlinear projected conjugate gradient method. Both examples of images from computer simulations and imaging experiments are analyzed, with results demonstrating the effectiveness of the proposed method.

  10. Snapshot 2D tomography via coded aperture x-ray scatter imaging.

    PubMed

    MacCabe, Kenneth P; Holmgren, Andrew D; Tornai, Martin P; Brady, David J

    2013-07-01

    This paper describes a fan beam coded aperture x-ray scatter imaging system that acquires a tomographic image from each snapshot. This technique exploits the cylindrical symmetry of the scattering cross section to avoid the scanning motion typically required by projection tomography. We use a coded aperture with a harmonic dependence to determine range and a shift code to determine cross range. Here we use a forward-scatter configuration to image 2D objects and use serial exposures to acquire tomographic video of motion within a plane. Our reconstruction algorithm also estimates the angular dependence of the scattered radiance, a step toward materials imaging and identification. PMID:23842254

  11. A comparison of 2D and 3D digital image correlation for a membrane under inflation

    NASA Astrophysics Data System (ADS)

    Murienne, Barbara J.; Nguyen, Thao D.

    2016-02-01

    Three-dimensional (3D) digital image correlation (DIC) is becoming widely used to characterize the behavior of structures undergoing 3D deformations. However, the use of 3D-DIC can be challenging under certain conditions, such as high magnification, and therefore small depth of field, or a highly controlled environment with limited access for two-angled cameras. The purpose of this study is to compare 2D-DIC and 3D-DIC for the same inflation experiment and evaluate whether 2D-DIC can be used when conditions discourage the use of a stereo-vision system. A latex membrane was inflated vertically to 5.41 kPa (reference pressure), then to 7.87 kPa (deformed pressure). A two-camera stereo-vision system acquired top-down images of the membrane, while a single camera system simultaneously recorded images of the membrane in profile. 2D-DIC and 3D-DIC were used to calculate horizontal (in the membrane plane) and vertical (out of the membrane plane) displacements, and meridional strain. Under static conditions, the baseline uncertainty in horizontal displacement and strain were smaller for 3D-DIC than 2D-DIC. However, the opposite was observed for the vertical displacement, for which 2D-DIC had a smaller baseline uncertainty. The baseline absolute error in vertical displacement and strain were similar for both DIC methods, but it was larger for 2D-DIC than 3D-DIC for the horizontal displacement. Under inflation, the variability in the measurements were larger than under static conditions for both DIC methods. 2D-DIC showed a smaller variability in displacements than 3D-DIC, especially for the vertical displacement, but a similar strain uncertainty. The absolute difference in the average displacements and strain between 3D-DIC and 2D-DIC were in the range of the 3D-DIC variability. Those findings suggest that 2D-DIC might be used as an alternative to 3D-DIC to study the inflation response of materials under certain conditions.

  12. 2D Doppler backscattering using synthetic aperture microwave imaging of MAST edge plasmas

    NASA Astrophysics Data System (ADS)

    Thomas, D. A.; Brunner, K. J.; Freethy, S. J.; Huang, B. K.; Shevchenko, V. F.; Vann, R. G. L.

    2016-02-01

    Doppler backscattering (DBS) is already established as a powerful diagnostic; its extension to 2D enables imaging of turbulence characteristics from an extended region of the cut-off surface. The Synthetic Aperture Microwave Imaging (SAMI) diagnostic has conducted proof-of-principle 2D DBS experiments of MAST edge plasma. SAMI actively probes the plasma edge using a wide (±40° vertical and horizontal) and tuneable (10-34.5 GHz) beam. The Doppler backscattered signal is digitised in vector form using an array of eight Vivaldi PCB antennas. This allows the receiving array to be focused in any direction within the field of view simultaneously to an angular range of 6-24° FWHM at 10-34.5 GHz. This capability is unique to SAMI and is a novel way of conducting DBS experiments. In this paper the feasibility of conducting 2D DBS experiments is explored. Initial observations of phenomena previously measured by conventional DBS experiments are presented; such as momentum injection from neutral beams and an abrupt change in power and turbulence velocity coinciding with the onset of H-mode. In addition, being able to carry out 2D DBS imaging allows a measurement of magnetic pitch angle to be made; preliminary results are presented. Capabilities gained through steering a beam using a phased array and the limitations of this technique are discussed.

  13. New applications for the touchscreen in 2D and 3D medical imaging workstations

    NASA Astrophysics Data System (ADS)

    Hinckley, Ken; Goble, John C.; Pausch, Randy; Kassell, Neal F.

    1995-04-01

    We present a new interface technique which augments a 3D user interface based on the physical manipulation of tools, or props, with a touchscreen. This hybrid interface intuitively and seamlessly combines 3D input with more traditional 2D input in the same user interface. Example 2D interface tasks of interest include selecting patient images from a database, browsing through axial, coronal, and sagittal image slices, or adjusting image center and window parameters. Note the facility with which a touchscreen can be used: the surgeon can move in 3D using the props, and then, without having to put the props down, the surgeon can reach out and touch the screen to perform 2D tasks. Based on previous work by Sears, we provide touchscreen users with visual feedback in the form of a small cursor which appears above the finger, allowing targets much smaller than the finger itself to be selected. Based on our informal user observations to date, this touchscreen stabilization algorithm allows targets as small as 1.08 mm X 1.08 mm to be selected by novices, and makes possible selection of targets as small as 0.27 mm X 0.27 mm after some training. Based on implemented prototype systems, we suggest that touchscreens offer not only intuitive 2D input which is well accepted by physicians, but that touchscreens also offer fast and accurate input which blends well with 3D interaction techniques.

  14. Blind estimation of affine transformation using 2D cyclostationarity of resampled images

    NASA Astrophysics Data System (ADS)

    Ou, Junhai; Ni, Jiangqun

    2015-12-01

    This paper presents a unified way to estimate the parameters of affine transformation in the absence of original image. With 2-D cyclostationary characterization, we analytically show that the covariance of affine transformed image is periodic with the affine transformation matrix. Based on the relationship between the affine transformation matrix and the position of resampling-caused striking peaks in the 2-D spectrum of the image's edge map, we further study how to estimate the parameters of several typical affine transformations, e.g., the scaling factor, the rotation angle, the joint scaling and rotation transformation parameters. Examples of the output of our algorithm are shown and comparative results are presented to evaluate the performance of the proposed algorithm.

  15. 2D array design based on Fermat spiral for ultrasound imaging.

    PubMed

    Martínez-Graullera, Oscar; Martín, Carlos J; Godoy, Gregorio; Ullate, Luis G

    2010-02-01

    The main challenge faced by 3D ultrasonic imaging with 2D array transducers is the large number of elements required to achieve an acceptable level of quality in the images. Therefore, the optimisation of the array layout, in order to reduce the number of active elements in the aperture, has been a research topic in the last years. Nowadays, array technology has made viable the production of 2D arrays with larger flexibility on elements size, shape and position, allowing to study other configurations different to the classical matrix organisation, such as circular, archimedes spiral or polygonal layout between others. In this work, the problem of designing an imaging system array with large apertures and a very limited number of active elements (N(e)=128 and N(e)=256) using the Fermat spiral layout has been studied. As summary, a general discussion about the most interesting cases is presented. PMID:19819510

  16. A wavelet relational fuzzy C-means algorithm for 2D gel image segmentation.

    PubMed

    Rashwan, Shaheera; Faheem, Mohamed Talaat; Sarhan, Amany; Youssef, Bayumy A B

    2013-01-01

    One of the most famous algorithms that appeared in the area of image segmentation is the Fuzzy C-Means (FCM) algorithm. This algorithm has been used in many applications such as data analysis, pattern recognition, and image segmentation. It has the advantages of producing high quality segmentation compared to the other available algorithms. Many modifications have been made to the algorithm to improve its segmentation quality. The proposed segmentation algorithm in this paper is based on the Fuzzy C-Means algorithm adding the relational fuzzy notion and the wavelet transform to it so as to enhance its performance especially in the area of 2D gel images. Both proposed modifications aim to minimize the oversegmentation error incurred by previous algorithms. The experimental results of comparing both the Fuzzy C-Means (FCM) and the Wavelet Fuzzy C-Means (WFCM) to the proposed algorithm on real 2D gel images acquired from human leukemias, HL-60 cell lines, and fetal alcohol syndrome (FAS) demonstrate the improvement achieved by the proposed algorithm in overcoming the segmentation error. In addition, we investigate the effect of denoising on the three algorithms. This investigation proves that denoising the 2D gel image before segmentation can improve (in most of the cases) the quality of the segmentation. PMID:24174990

  17. Progressive attenuation fields: Fast 2D-3D image registration without precomputation

    SciTech Connect

    Rohlfing, Torsten; Russakoff, Daniel B.; Denzler, Joachim; Mori, Kensaku; Maurer, Calvin R. Jr.

    2005-09-15

    Computation of digitally reconstructed radiograph (DRR) images is the rate-limiting step in most current intensity-based algorithms for the registration of three-dimensional (3D) images to two-dimensional (2D) projection images. This paper introduces and evaluates the progressive attenuation field (PAF), which is a new method to speed up DRR computation. A PAF is closely related to an attenuation field (AF). A major difference is that a PAF is constructed on the fly as the registration proceeds; it does not require any precomputation time, nor does it make any prior assumptions of the patient pose or limit the permissible range of patient motion. A PAF effectively acts as a cache memory for projection values once they are computed, rather than as a lookup table for precomputed projections like standard AFs. We use a cylindrical attenuation field parametrization, which is better suited for many medical applications of 2D-3D registration than the usual two-plane parametrization. The computed attenuation values are stored in a hash table for time-efficient storage and access. Using clinical gold-standard spine image data sets from five patients, we demonstrate consistent speedups of intensity-based 2D-3D image registration using PAF DRRs by a factor of 10 over conventional ray casting DRRs with no decrease of registration accuracy or robustness.

  18. A Wavelet Relational Fuzzy C-Means Algorithm for 2D Gel Image Segmentation

    PubMed Central

    Rashwan, Shaheera; Faheem, Mohamed Talaat; Sarhan, Amany; Youssef, Bayumy A. B.

    2013-01-01

    One of the most famous algorithms that appeared in the area of image segmentation is the Fuzzy C-Means (FCM) algorithm. This algorithm has been used in many applications such as data analysis, pattern recognition, and image segmentation. It has the advantages of producing high quality segmentation compared to the other available algorithms. Many modifications have been made to the algorithm to improve its segmentation quality. The proposed segmentation algorithm in this paper is based on the Fuzzy C-Means algorithm adding the relational fuzzy notion and the wavelet transform to it so as to enhance its performance especially in the area of 2D gel images. Both proposed modifications aim to minimize the oversegmentation error incurred by previous algorithms. The experimental results of comparing both the Fuzzy C-Means (FCM) and the Wavelet Fuzzy C-Means (WFCM) to the proposed algorithm on real 2D gel images acquired from human leukemias, HL-60 cell lines, and fetal alcohol syndrome (FAS) demonstrate the improvement achieved by the proposed algorithm in overcoming the segmentation error. In addition, we investigate the effect of denoising on the three algorithms. This investigation proves that denoising the 2D gel image before segmentation can improve (in most of the cases) the quality of the segmentation. PMID:24174990

  19. Comparison of spatiotemporal interpolators for 4D image reconstruction from 2D transesophageal ultrasound

    NASA Astrophysics Data System (ADS)

    Haak, Alexander; van Stralen, Marijn; van Burken, Gerard; Klein, Stefan; Pluim, Josien P. W.; de Jong, Nico; van der Steen, Antonius F. W.; Bosch, Johan G.

    2012-03-01

    °For electrophysiology intervention monitoring, we intend to reconstruct 4D ultrasound (US) of structures in the beating heart from 2D transesophageal US by scanplane rotation. The image acquisition is continuous but unsynchronized to the heart rate, which results in a sparsely and irregularly sampled dataset and a spatiotemporal interpolation method is desired. Previously, we showed the potential of normalized convolution (NC) for interpolating such datasets. We explored 4D interpolation by 3 different methods: NC, nearest neighbor (NN), and temporal binning followed by linear interpolation (LTB). The test datasets were derived by slicing three 4D echocardiography datasets at random rotation angles (θ, range: 0-180) and random normalized cardiac phase (τ, range: 0-1). Four different distributions of rotated 2D images with 600, 900, 1350, and 1800 2D input images were created from all TEE sets. A 2D Gaussian kernel was used for NC and optimal kernel sizes (σθ and στ) were found by performing an exhaustive search. The RMS gray value error (RMSE) of the reconstructed images was computed for all interpolation methods. The estimated optimal kernels were in the range of σθ = 3.24 - 3.69°/ στ = 0.045 - 0.048, σθ = 2.79°/ στ = 0.031 - 0.038, σθ = 2.34°/ στ = 0.023 - 0.026, and σθ = 1.89°/ στ = 0.021 - 0.023 for 600, 900, 1350, and 1800 input images respectively. We showed that NC outperforms NN and LTB. For a small number of input images the advantage of NC is more pronounced.

  20. Intra-Cardiac 2D US to 3D CT Image Registration

    NASA Astrophysics Data System (ADS)

    Huang, Xishi; Hill, Nicholas A.; Ren, Jing; Guiraudon, Gerard; Peters, Terry M.

    2007-03-01

    Intra-cardiac echocardiography (ICE) is commonly used to guide intra-cardiac procedures, such as the treatment of atrial fibrillation (AF). However, effective surgical navigation based on ICE images is not trivial, due to the low signal-to-noise ratio (SNR) and limited field of view of ultrasound (US) images. The interpretation of ICE can be significantly improved if correctly placed in the context of three-dimensional magnetic resonance (MR) or computed tomography (CT) images by simultaneously presenting the complementary anatomical information from the two modalities. The purpose of this research is to demonstrate the feasibility of multimodality image registration of 2D intra-cardiac US images with 3D computed tomography (CT) images. In our previous work, a two-step registration procedure has been proposed to register US images with MR images and was validated on a patient dataset. In this work, we extend the two-step method to intra-cardiac procedures and provide a detailed assessment of registration accuracy by determining the target registration errors (TRE) on a heart phantom, which had fiducial markers affixed to the surface to facilitate evaluation of registration accuracy. The resultant TRE on the heart phantom was 3.7 mm. This result is considered to be acceptable for guiding a probe in the heart during ablative therapy for atrial fibrillation. To our knowledge, there is no previous report describing multimodality registration of 2D intra-cardiac US to high-resolution 3D CT.

  1. Simultaneous 3D–2D image registration and C-arm calibration: Application to endovascular image-guided interventions

    SciTech Connect

    Mitrović, Uroš; Pernuš, Franjo; Likar, Boštjan; Špiclin, Žiga

    2015-11-15

    Purpose: Three-dimensional to two-dimensional (3D–2D) image registration is a key to fusion and simultaneous visualization of valuable information contained in 3D pre-interventional and 2D intra-interventional images with the final goal of image guidance of a procedure. In this paper, the authors focus on 3D–2D image registration within the context of intracranial endovascular image-guided interventions (EIGIs), where the 3D and 2D images are generally acquired with the same C-arm system. The accuracy and robustness of any 3D–2D registration method, to be used in a clinical setting, is influenced by (1) the method itself, (2) uncertainty of initial pose of the 3D image from which registration starts, (3) uncertainty of C-arm’s geometry and pose, and (4) the number of 2D intra-interventional images used for registration, which is generally one and at most two. The study of these influences requires rigorous and objective validation of any 3D–2D registration method against a highly accurate reference or “gold standard” registration, performed on clinical image datasets acquired in the context of the intervention. Methods: The registration process is split into two sequential, i.e., initial and final, registration stages. The initial stage is either machine-based or template matching. The latter aims to reduce possibly large in-plane translation errors by matching a projection of the 3D vessel model and 2D image. In the final registration stage, four state-of-the-art intrinsic image-based 3D–2D registration methods, which involve simultaneous refinement of rigid-body and C-arm parameters, are evaluated. For objective validation, the authors acquired an image database of 15 patients undergoing cerebral EIGI, for which accurate gold standard registrations were established by fiducial marker coregistration. Results: Based on target registration error, the obtained success rates of 3D to a single 2D image registration after initial machine-based and template matching and final registration involving C-arm calibration were 36%, 73%, and 93%, respectively, while registration accuracy of 0.59 mm was the best after final registration. By compensating in-plane translation errors by initial template matching, the success rates achieved after the final stage improved consistently for all methods, especially if C-arm calibration was performed simultaneously with the 3D–2D image registration. Conclusions: Because the tested methods perform simultaneous C-arm calibration and 3D–2D registration based solely on anatomical information, they have a high potential for automation and thus for an immediate integration into current interventional workflow. One of the authors’ main contributions is also comprehensive and representative validation performed under realistic conditions as encountered during cerebral EIGI.

  2. Localization and tracking of aortic valve prosthesis in 2D fluoroscopic image sequences

    NASA Astrophysics Data System (ADS)

    Karar, M.; Chalopin, C.; Merk, D. R.; Jacobs, S.; Walther, T.; Burgert, O.; Falk, V.

    2009-02-01

    This paper presents a new method for localization and tracking of the aortic valve prosthesis (AVP) in 2D fluoroscopic image sequences to assist the surgeon to reach the safe zone of implantation during transapical aortic valve implantation. The proposed method includes four main steps: First, the fluoroscopic images are preprocessed using a morphological reconstruction and an adaptive Wiener filter to enhance the AVP edges. Second, a target window, defined by a user on the first image of the sequences which includes the AVP, is tracked in all images using a template matching algorithm. In a third step the corners of the AVP are extracted based on the AVP dimensions and orientation in the target window. Finally, the AVP model is generated in the fluoroscopic image sequences. Although the proposed method is not yet validated intraoperatively, it has been applied to different fluoroscopic image sequences with promising results.

  3. Offline estimation of 2 D crystal lattice parameters by processing the electron diffraction image

    NASA Astrophysics Data System (ADS)

    Haq, Nuhman ul; Hayat, Khizar; Madani, Sajjad A.; Iqbal, Yaseen

    2012-03-01

    Electron diffraction provides useful information about the internal composition of materials and has been in the use of material scientists for more than fifty years. In order to extract useful information from offline diffraction images, they are manually analyzed by using some photometric technique. Manual analysis is however a cumbersome, laborious and difficult task. To reduce the labors of material scientists one can employ image processing techniques to perform automated analysis, due to the well established popularity and clear evidence of widely used image processing techniques. In this work an image processing technique is being proposed for the extraction of 2D unit cell information from diffraction images on one hand and finding the 2D point group contained by the lattices on the other. The technique employs a morphological shrinking operation to find the center of each spot in the underlying preprocessed diffraction image. This is followed by the extraction of eight points with reference to the spot produced by the transmitted electron beam. The resultant nine points, i.e. the extracted eight plus the reference spot generated by the transmitted electron beam, are then subjected to symmetry operations, rotation symmetry and mirror symmetry, in polar coordinate system, to classify the point group of the lattice produced by the electron diffraction. One of the difficult task, even in manual analysis, is to ascertain the exact spot where the transmitted electron beam hit the sample at the time of realization of the image. This has been accurately and intuitively done by employing the notion that the transmitted spot must have greater number of pixels, with the highest gray value, among the diffracted spots. The proposed strategy has been applied to a sample set of various images and the results shows that the technique is efficient in determining the unit cell in 2D and classify the point group with good accuracy.

  4. 2D Ultrasound and 3D MR Image Registration of the Prostate for Brachytherapy Surgical Navigation

    PubMed Central

    Zhang, Shihui; Jiang, Shan; Yang, Zhiyong; Liu, Ranlu

    2015-01-01

    Abstract Two-dimensional (2D) ultrasound (US) images are widely used in minimally invasive prostate procedure for its noninvasive nature and convenience. However, the poor quality of US image makes it difficult to be used as guiding utility. To improve the limitation, we propose a multimodality image guided navigation module that registers 2D US images with magnetic resonance imaging (MRI) based on high quality preoperative models. A 2-step spatial registration method is used to complete the procedure which combines manual alignment and rapid mutual information (MI) optimize algorithm. In addition, a 3-dimensional (3D) reconstruction model of prostate with surrounding organs is employed to combine with the registered images to conduct the navigation. Registration accuracy is measured by calculating the target registration error (TRE). The results show that the error between the US and preoperative MR images of a polyvinyl alcohol hydrogel model phantom is 1.37 ± 0.14 mm, with a similar performance being observed in patient experiments. PMID:26448009

  5. 2D Ultrasound and 3D MR Image Registration of the Prostate for Brachytherapy Surgical Navigation.

    PubMed

    Zhang, Shihui; Jiang, Shan; Yang, Zhiyong; Liu, Ranlu

    2015-10-01

    Two-dimensional (2D) ultrasound (US) images are widely used in minimally invasive prostate procedure for its noninvasive nature and convenience. However, the poor quality of US image makes it difficult to be used as guiding utility. To improve the limitation, we propose a multimodality image guided navigation module that registers 2D US images with magnetic resonance imaging (MRI) based on high quality preoperative models. A 2-step spatial registration method is used to complete the procedure which combines manual alignment and rapid mutual information (MI) optimize algorithm. In addition, a 3-dimensional (3D) reconstruction model of prostate with surrounding organs is employed to combine with the registered images to conduct the navigation. Registration accuracy is measured by calculating the target registration error (TRE). The results show that the error between the US and preoperative MR images of a polyvinyl alcohol hydrogel model phantom is 1.37 ± 0.14 mm, with a similar performance being observed in patient experiments. PMID:26448009

  6. Image Pretreatment Tools II: Normalization Techniques for 2-DE and 2-D DIGE.

    PubMed

    Robotti, Elisa; Marengo, Emilio; Quasso, Fabio

    2016-01-01

    Gel electrophoresis is usually applied to identify different protein expression profiles in biological samples (e.g., control vs. pathological, control vs. treated). Information about the effect to be investigated (a pathology, a drug, a ripening effect, etc.) is however generally confounded with experimental variability that is quite large in 2-DE and may arise from small variations in the sample preparation, reagents, sample loading, electrophoretic conditions, staining and image acquisition. Obtaining valid quantitative estimates of protein abundances in each map, before the differential analysis, is therefore fundamental to provide robust candidate biomarkers. Normalization procedures are applied to reduce experimental noise and make the images comparable, improving the accuracy of differential analysis. Certainly, they may deeply influence the final results, and to this respect they have to be applied with care. Here, the most widespread normalization procedures are described both for what regards the applications to 2-DE and 2D Difference Gel-electrophoresis (2-D DIGE) maps. PMID:26611411

  7. Novel fabrication of a 2D ring array for real-time volumetric endoscopic ultrasound imaging.

    PubMed

    Sun, Shiyue; Wu, Dawei; Zhu, Benpeng; Zhang, Yue; Chen, Shi; Yang, Xiaofei

    2015-07-01

    The work presents the development of a forward-looking 2D ring array for real-time volumetric endoscopic ultrasonic imaging using a novel rotary-dicing method. The completed array has an inner diameter of 3.5 mm, outer diameter of 5 mm, and 50 equal-area elements distributed concentrically. With a single front matching layer and a light backing, the array shows a center frequency of 3.5 MHz, a fractional bandwidth of 48%, insertion loss of -21.6 dB and cross-talk between nearest neighbor elements of 35.3 dB. The beam profile, two-dimensional pulse-echo point spread response, and phantom imaging of the array were studied with the Field-II simulation package. These promising results suggest that the rotary-dicing technology is an effective way to fabricate 2D ring array. PMID:25771298

  8. Preliminary work of real-time ultrasound imaging system for 2-D array transducer.

    PubMed

    Li, Xu; Yang, Jiali; Ding, Mingyue; Yuchi, Ming

    2015-01-01

    Ultrasound (US) has emerged as a non-invasive imaging modality that can provide anatomical structure information in real time. To enable the experimental analysis of new 2-D array ultrasound beamforming methods, a pre-beamformed parallel raw data acquisition system was developed for 3-D data capture of 2D array transducer. The transducer interconnection adopted the row-column addressing (RCA) scheme, where the columns and rows were active in sequential for transmit and receive events, respectively. The DAQ system captured the raw data in parallel and the digitized data were fed through the field programmable gate array (FPGA) to implement the pre-beamforming. Finally, 3-D images were reconstructed through the devised platform in real-time. PMID:26405923

  9. Calibration model of a dual gain flat panel detector for 2D and 3D x-ray imaging

    SciTech Connect

    Schmidgunst, C.; Ritter, D.; Lang, E.

    2007-09-15

    The continuing research and further development in flat panel detector technology have led to its integration into more and more medical x-ray systems for two-dimensional (2D) and three-dimensional (3D) imaging, such as fixed or mobile C arms. Besides the obvious advantages of flat panel detectors, like the slim design and the resulting optimum accessibility to the patient, their success is primarily a product of the image quality that can be achieved. The benefits in the physical and performance-related features as opposed to conventional image intensifier systems (e.g., distortion-free reproduction of imaging information or almost linear signal response over a large dynamic range) can be fully exploited, however, only if the raw detector images are correctly calibrated and postprocessed. Previous procedures for processing raw data contain idealizations that, in the real world, lead to artifacts or losses in image quality. Thus, for example, temperature dependencies or changes in beam geometry, as can occur with mobile C arm systems, have not been taken into account up to this time. Additionally, adverse characteristics such as image lag or aging effects have to be compensated to attain the best possible image quality. In this article a procedure is presented that takes into account the important dependencies of the individual pixel sensitivity of flat panel detectors used in 2D or 3D imaging and simultaneously minimizes the work required for an extensive recalibration. It is suitable for conventional detectors with only one gain mode as well as for the detectors specially developed for 3D imaging with dual gain read-out technology.

  10. Imaging collective magnonic modes in 2D arrays of magnetic nanoelements.

    PubMed

    Kruglyak, V V; Keatley, P S; Neudert, A; Hicken, R J; Childress, J R; Katine, J A

    2010-01-15

    We have used time resolved scanning Kerr microscopy to image collective spin wave modes within a 2D array of magnetic nanoelements. Long wavelength spin waves are confined within the array as if it was a continuous element of the same size but with effective material properties determined by the structure of the array and its constituent nanoelements. The array is an example of a magnonic metamaterial, the demonstration of which provides new opportunities within the emerging field of magnonics. PMID:20366622

  11. Imaging Collective Magnonic Modes in 2D Arrays of Magnetic Nanoelements

    NASA Astrophysics Data System (ADS)

    Kruglyak, V. V.; Keatley, P. S.; Neudert, A.; Hicken, R. J.; Childress, J. R.; Katine, J. A.

    2010-01-01

    We have used time resolved scanning Kerr microscopy to image collective spin wave modes within a 2D array of magnetic nanoelements. Long wavelength spin waves are confined within the array as if it was a continuous element of the same size but with effective material properties determined by the structure of the array and its constituent nanoelements. The array is an example of a magnonic metamaterial, the demonstration of which provides new opportunities within the emerging field of magnonics.

  12. Image quality of up-converted 2D video from frame-compatible 3D video

    NASA Astrophysics Data System (ADS)

    Speranza, Filippo; Tam, Wa James; Vázquez, Carlos; Renaud, Ronald; Blanchfield, Phil

    2011-03-01

    In the stereoscopic frame-compatible format, the separate high-definition left and high-definition right views are reduced in resolution and packed to fit within the same video frame as a conventional two-dimensional high-definition signal. This format has been suggested for 3DTV since it does not require additional transmission bandwidth and entails only small changes to the existing broadcasting infrastructure. In some instances, the frame-compatible format might be used to deliver both 2D and 3D services, e.g., for over-the-air television services. In those cases, the video quality of the 2D service is bound to decrease since the 2D signal will have to be generated by up-converting one of the two views. In this study, we investigated such loss by measuring the perceptual image quality of 1080i and 720p up-converted video as compared to that of full resolution original 2D video. The video was encoded with either a MPEG-2 or a H.264/AVC codec at different bit rates and presented for viewing with either no polarized glasses (2D viewing mode) or with polarized glasses (3D viewing mode). The results confirmed a loss of video quality of the 2D video up-converted material. The loss due to the sampling processes inherent to the frame-compatible format was rather small for both 1080i and 720p video formats; the loss became more substantial with encoding, particularly for MPEG-2 encoding. The 3D viewing mode provided higher quality ratings, possibly because the visibility of the degradations was reduced.

  13. Fully automatic detection of the vertebrae in 2D CT images

    NASA Astrophysics Data System (ADS)

    Graf, Franz; Kriegel, Hans-Peter; Schubert, Matthias; Strukelj, Michael; Cavallaro, Alexander

    2011-03-01

    Knowledge about the vertebrae is a valuable source of information for several annotation tasks. In recent years, the research community spent a considerable effort for detecting, segmenting and analyzing the vertebrae and the spine in various image modalities like CT or MR. Most of these methods rely on prior knowledge like the location of the vertebrae or other initial information like the manual detection of the spine. Furthermore, the majority of these methods require a complete volume scan. With the existence of use cases where only a single slice is available, there arises a demand for methods allowing the detection of the vertebrae in 2D images. In this paper, we propose a fully automatic and parameterless algorithm for detecting the vertebrae in 2D CT images. Our algorithm starts with detecting candidate locations by taking the density of bone-like structures into account. Afterwards, the candidate locations are extended into candidate regions for which certain image features are extracted. The resulting feature vectors are compared to a sample set of previously annotated and processed images in order to determine the best candidate region. In a final step, the result region is readjusted until convergence to a locally optimal position. Our new method is validated on a real world data set of more than 9 329 images of 34 patients being annotated by a clinician in order to provide a realistic ground truth.

  14. Image compression and encryption scheme based on 2D compressive sensing and fractional Mellin transform

    NASA Astrophysics Data System (ADS)

    Zhou, Nanrun; Li, Haolin; Wang, Di; Pan, Shumin; Zhou, Zhihong

    2015-05-01

    Most of the existing image encryption techniques bear security risks for taking linear transform or suffer encryption data expansion for adopting nonlinear transformation directly. To overcome these difficulties, a novel image compression-encryption scheme is proposed by combining 2D compressive sensing with nonlinear fractional Mellin transform. In this scheme, the original image is measured by measurement matrices in two directions to achieve compression and encryption simultaneously, and then the resulting image is re-encrypted by the nonlinear fractional Mellin transform. The measurement matrices are controlled by chaos map. The Newton Smoothed l0 Norm (NSL0) algorithm is adopted to obtain the decryption image. Simulation results verify the validity and the reliability of this scheme.

  15. Mathematical models used in segmentation and fractal methods of 2-D ultrasound images

    NASA Astrophysics Data System (ADS)

    Moldovanu, Simona; Moraru, Luminita; Bibicu, Dorin

    2012-11-01

    Mathematical models are widely used in biomedical computing. The extracted data from images using the mathematical techniques are the "pillar" achieving scientific progress in experimental, clinical, biomedical, and behavioural researches. This article deals with the representation of 2-D images and highlights the mathematical support for the segmentation operation and fractal analysis in ultrasound images. A large number of mathematical techniques are suitable to be applied during the image processing stage. The addressed topics cover the edge-based segmentation, more precisely the gradient-based edge detection and active contour model, and the region-based segmentation namely Otsu method. Another interesting mathematical approach consists of analyzing the images using the Box Counting Method (BCM) to compute the fractal dimension. The results of the paper provide explicit samples performed by various combination of methods.

  16. Solid H2/D2 Particle Seeding and Injection System for Particle Image Velocimetry (PIV) Measurement of He II

    SciTech Connect

    Xu, T.; Van Sciver, S. W.

    2006-04-27

    Solid particles of the mixture of hydrogen and deuterium have certain advantages for use in Particle Image Velocimetry (PIV) of He II flow. The H2/D2 particles are near neutrally buoyant in He II and will vaporize with the helium as the experimental apparatus is warmed to room temperature. Progress of the construction of a H2/D2 particle seeding and injection system is reported in this paper. A cryogenic pulse valve is used to inject the mixture of helium, hydrogen and deuterium gas directly into a He II bath. Experiments show that the seeding quality is dependent on the back pressure, the mix ratio of the deuterium and helium gases and valve open duration. The effects of these parameters on the solid deuterium particle distribution are also discussed.

  17. Visualizing 2D Probability Distributions from Satellite Image-Derived Data

    NASA Technical Reports Server (NTRS)

    Kao, David; Dungan, Jennifer; Pang, Alex; Biegel, Bryan (Technical Monitor)

    2002-01-01

    Creating maps of biophysical and geophysical variables using Earth Observing System (EOS) satellite image data is an important component of Earth science. These 2D maps have a single value at every location and standard techniques are used to visualize them. Current tools fall short, however, when it is necessary to describe a distribution of values at each location. Distributions may represent a frequency of occurrence over time, frequency of occurrence from multiple runs of an ensemble forecast or possible values from an uncertainty model. 'Distribution data sets' are described, then a case study is presented to visualize such 2D distributions. Distribution data sets are different from multivariate data sets in the sense that the values are for a single variable instead of multiple variables. Our case study data consists of multiple realizations of percent forest cover, generated using a geostatistical technique that combines ground measurements and satellite imagery to model uncertainty about forest cover. We present several approaches for analyzing and visualizing such data sets. The first is a pixel-wise analysis of the probability density functions for the 2D image while the second is an analysis of features identified within the image. Such pixel-wise and feature-wise views will give Earth scientists a more complete understanding of distribution data sets.

  18. Filters in 2D and 3D Cardiac SPECT Image Processing

    PubMed Central

    Ploussi, Agapi; Synefia, Stella

    2014-01-01

    Nuclear cardiac imaging is a noninvasive, sensitive method providing information on cardiac structure and physiology. Single photon emission tomography (SPECT) evaluates myocardial perfusion, viability, and function and is widely used in clinical routine. The quality of the tomographic image is a key for accurate diagnosis. Image filtering, a mathematical processing, compensates for loss of detail in an image while reducing image noise, and it can improve the image resolution and limit the degradation of the image. SPECT images are then reconstructed, either by filter back projection (FBP) analytical technique or iteratively, by algebraic methods. The aim of this study is to review filters in cardiac 2D, 3D, and 4D SPECT applications and how these affect the image quality mirroring the diagnostic accuracy of SPECT images. Several filters, including the Hanning, Butterworth, and Parzen filters, were evaluated in combination with the two reconstruction methods as well as with a specified MatLab program. Results showed that for both 3D and 4D cardiac SPECT the Butterworth filter, for different critical frequencies and orders, produced the best results. Between the two reconstruction methods, the iterative one might be more appropriate for cardiac SPECT, since it improves lesion detectability due to the significant improvement of image contrast. PMID:24804144

  19. Mid-IR hyperspectral imaging of laminar flames for 2-D scalar values.

    PubMed

    Rhoby, Michael R; Blunck, David L; Gross, Kevin C

    2014-09-01

    This work presents a new emission-based measurement which permits quantification of two-dimensional scalar distributions in laminar flames. A Michelson-based Fourier-transform spectrometer coupled to a mid-infrared camera (1.5 μm to 5.5 μm) obtained 256 × 128pixel hyperspectral flame images at high spectral (δν̃ = 0.75cm(−1)) and spatial (0.52 mm) resolutions. The measurements revealed line and band emission from H2O, CO2, and CO. Measurements were collected from a well-characterized partially-premixed ethylene (C2H4) flame produced on a Hencken burner at equivalence ratios, Φ, of 0.8, 0.9, 1.1, and 1.3. After describing the instrument and novel calibration methodology, analysis of the flames is presented. A single-layer, line-by-line radiative transfer model is used to retrieve path-averaged temperature, H2O, CO2 and CO column densities from emission spectra between 2.3 μm to 5.1 μm. The radiative transfer model uses line intensities from the latest HITEMP and CDSD-4000 spectroscopic databases. For the Φ = 1.1 flame, the spectrally estimated temperature for a single pixel 10 mm above burner center was T = (2318 ± 19)K, and agrees favorably with recently reported laser absorption measurements, T = (2348 ± 115)K, and a NASA CEA equilibrium calculation, T = 2389K. Near the base of the flame, absolute concentrations can be estimated, and H2O, CO2, and CO concentrations of (12.5 ± 1.7) %, (10.1 ± 1.0) %, and (3.8 ± 0.3) %, respectively, compared favorably with the corresponding CEA values of 12.8%, 9.9% and 4.1%. Spectrally-estimated temperatures and concentrations at the other equivalence ratios were in similar agreement with measurements and equilibrium calculations. 2-D temperature and species column density maps underscore the Φ-dependent chemical composition of the flames. The reported uncertainties are 95% confidence intervals and include both statistical fit errors and the propagation of systematic calibration errors using a Monte Carlo approach. Systematic errors could warrant a factor of two increase in reported uncertainties. This work helps to establish IFTS as a valuable combustion diagnostic tool. PMID:25321539

  20. Effective Temperature of 2D Dusty Plasma Liquids at the Discrete Level

    SciTech Connect

    Io, C.-W.; Chan, C.-L.; I Lin

    2007-07-13

    Fluctuation-dissipation theory has been used to measure the effective temperature of non-equilibrium system. In this work, using a 2D dusty plasma liquid formed by the negatively charged fine particles suspending in weakly ionized discharges and sheared by two CW counter parallel laser beams, we measure the micro-transport at the kinetic level. The effective temperatures Teff at different time scales are obtained through the Stokes-Einstein relation which relates the diffusion coefficient (D) and the viscosity ({eta}). The external energy is cascaded from the slow hopping modes to the fast caging modes through mutual coupling, which leads to the higher effective temperature of the slow hopping modes.

  1. Distinguishing Electronic and Vibronic Coherence in 2D Spectra by Their Temperature Dependence

    PubMed Central

    2014-01-01

    Long-lived oscillations in 2D spectra of chlorophylls are at the heart of an ongoing debate. Their physical origin is either a multipigment effect, such as excitonic coherence, or localized vibrations. We show how relative phase differences of diagonal- and cross-peak oscillations can distinguish between electronic and vibrational (vibronic) effects. While direct discrimination between the two scenarios is obscured when peaks overlap, their sensitivity to temperature provides a stronger argument. We show that vibrational (vibronic) oscillations change relative phase with temperature, while electronic oscillations are only weakly dependent. This highlights that studies of relative phase difference as a function of temperature provide a clear and easily accessible method to distinguish between vibrational and electronic coherences. PMID:24527180

  2. Room temperature synthesis of 2D CuO nanoleaves in aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Zhao, Jingzhe; Li, Yunling; Ma, Dechong; Hou, Shengnan; Li, Linzhi; Hao, Xinli; Wang, Zichen

    2011-03-01

    A simple room temperature method was reported for the synthesis of CuO nanocrystals in aqueous solution through the sequence of {Cu}^{2+} \\to {Cu(OA)}_{2} \\to {Cu(OH)}_{2} \\to {Cu(OH)}_{4}^{2-}\\allowbreak \\to {CuO} . Sodium oleate (SOA) was used as the surfactant and shape controller. The as-prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectroscopy (UV-vis) and differential thermal analysis (DTA). It can be seen that 1D Cu(OH)2 nanowires were first obtained from Cu(OA)2 and, at room temperature, converted into 2D CuO nanoleaves (CuO NLs) in a short time under a weakly basic environment. On prolonging the reaction time, the top part of these 2D nanoleaves branched and separated along the long axis to form 1D rod-like nano-CuO because of the assistance of SOA. A possible transformation mechanism of Cu(OH)2 to CuO nanostructures at room temperature in aqueous solution is discussed. The transformation velocity can be controlled by changing the pH value of the system. The prepared CuO NLs were used to construct an enzyme-free glucose sensor. The detecting results showed that the designed sensor exhibited good amperometric responses towards glucose with good anti-interferent ability.

  3. Non-rigid target tracking in 2D ultrasound images using hierarchical grid interpolation

    NASA Astrophysics Data System (ADS)

    Royer, Lucas; Babel, Marie; Krupa, Alexandre

    2014-03-01

    In this paper, we present a new non-rigid target tracking method within 2D ultrasound (US) image sequence. Due to the poor quality of US images, the motion tracking of a tumor or cyst during needle insertion is considered as an open research issue. Our approach is based on well-known compression algorithm in order to make our method work in real-time which is a necessary condition for many clinical applications. Toward that end, we employed a dedicated hierarchical grid interpolation algorithm (HGI) which can represent a large variety of deformations compared to other motion estimation algorithms such as Overlapped Block Motion Compensation (OBMC), or Block Motion Algorithm (BMA). The sum of squared difference of image intensity is selected as similarity criterion because it provides a good trade-off between computation time and motion estimation quality. Contrary to the others methods proposed in the literature, our approach has the ability to distinguish both rigid and non-rigid motions which are observed in ultrasound image modality. Furthermore, this technique does not take into account any prior knowledge about the target, and limits the user interaction which usually complicates the medical validation process. Finally, a technique aiming at identifying the main phases of a periodic motion (e.g. breathing motion) is introduced. The new approach has been validated from 2D ultrasound images of real human tissues which undergo rigid and non-rigid deformations.

  4. X-Ray Phase-Contrast Imaging with Three 2D Gratings

    PubMed Central

    Jiang, Ming; Wyatt, Christopher Lee; Wang, Ge

    2008-01-01

    X-ray imaging is of paramount importance for clinical and preclinical imaging but it is fundamentally restricted by the attenuation-based contrast mechanism, which has remained essentially the same since Roentgen's discovery a century ago. Recently, based on the Talbot effect, groundbreaking work was reported using 1D gratings for X-ray phase-contrast imaging with a hospital-grade X-ray tube instead of a synchrotron or microfocused source. In this paper, we report an extension using 2D gratings that reduces the imaging time and increases the accuracy and robustness of phase retrieval compared to current grating-based phase-contrast techniques. Feasibility is demonstrated via numerical simulation. PMID:18401460

  5. Electron Microscopy: From 2D to 3D Images with Special Reference to Muscle

    PubMed Central

    2015-01-01

    This is a brief and necessarily very sketchy presentation of the evolution in electron microscopy (EM) imaging that was driven by the necessity of extracting 3-D views from the essentially 2-D images produced by the electron beam. The lens design of standard transmission electron microscope has not been greatly altered since its inception. However, technical advances in specimen preparation, image collection and analysis gradually induced an astounding progression over a period of about 50 years. From the early images that redefined tissues, cell and cell organelles at the sub-micron level, to the current nano-resolution reconstructions of organelles and proteins the step is very large. The review is written by an investigator who has followed the field for many years, but often from the sidelines, and with great wonder. Her interest in muscle ultrastructure colors the writing. More specific detailed reviews are presented in this issue. PMID:26913146

  6. 2D velocity and temperature measurements in high speed flows based on spectrally resolved Rayleigh scattering

    NASA Technical Reports Server (NTRS)

    Seasholtz, Richard G.

    1992-01-01

    The use of molecular Rayleigh scattering for measurements of gas velocity and temperature is evaluated. Molecular scattering avoids problems associated with the seeding required by conventional laser anemometry and particle image velocimetry. The technique considered herein is based on the measurement of the spectrum of the scattered light. Planar imaging of Rayleigh scattering using a laser light sheet is evaluated for conditions at 30 km altitude (typical hypersonic flow conditions). The Cramer-Rao lower bounds for velocity and temperature measurement uncertainties are calculated for an ideal optical spectrum analyzer and for a planar mirror Fabry-Perot interferometer used in a static, imaging mode. With this technique, a single image of the Rayleigh scattered light from clean flows can be analyzed to obtain temperature and one component of velocity. Experimental results are presented for planar velocity measurements in a Mach 1.3 air jet.

  7. A 3D Feature Descriptor Recovered from a Single 2D Palmprint Image.

    PubMed

    Zheng, Qian; Kumar, Ajay; Pan, Gang

    2016-06-01

    Design and development of efficient and accurate feature descriptors is critical for the success of many computer vision applications. This paper proposes a new feature descriptor, referred to as DoN, for the 2D palmprint matching. The descriptor is extracted for each point on the palmprint. It is based on the ordinal measure which partially describes the difference of the neighboring points' normal vectors. DoN has at least two advantages: 1) it describes the 3D information, which is expected to be highly stable under commonly occurring illumination variations during contactless imaging; 2) the size of DoN for each point is only one bit, which is computationally simple to extract, easy to match, and efficient to storage. We show that such 3D information can be extracted from a single 2D palmprint image. The analysis for the effectiveness of ordinal measure for palmprint matching is also provided. Four publicly available 2D palmprint databases are used to evaluate the effectiveness of DoN, both for identification and the verification. Our method on all these databases achieves the state-of-the-art performance. PMID:27164564

  8. Clinical Assessment of 2D/3D Registration Accuracy in 4 Major Anatomic Sites Using On-Board 2D Kilovoltage Images for 6D Patient Setup

    PubMed Central

    Li, Guang; Yang, T. Jonathan; Furtado, Hugo; Birkfellner, Wolfgang; Ballangrud, Åse; Powell, Simon N.; Mechalakos, James

    2015-01-01

    To provide a comprehensive assessment of patient setup accuracy in 6 degrees of freedom (DOFs) using 2-dimensional/3-dimensional (2D/3D) image registration with on-board 2-dimensional kilovoltage (OB-2DkV) radiographic images, we evaluated cranial, head and neck (HN), and thoracic and abdominal sites under clinical conditions. A fast 2D/3D image registration method using graphics processing unit GPU was modified for registration between OB-2DkV and 3D simulation computed tomography (simCT) images, with 3D/3D registration as the gold standard for 6DOF alignment. In 2D/3D registration, body roll rotation was obtained solely by matching orthogonal OB-2DkV images with a series of digitally reconstructed radiographs (DRRs) from simCT with a small rotational increment along the gantry rotation axis. The window/level adjustments for optimal visualization of the bone in OB-2DkV and DRRs were performed prior to registration. Ideal patient alignment at the isocenter was calculated and used as an initial registration position. In 3D/3D registration, cone-beam CT (CBCT) was aligned to simCT on bony structures using a bone density filter in 6DOF. Included in this retrospective study were 37 patients treated in 55 fractions with frameless stereotactic radiosurgery or stereotactic body radiotherapy for cranial and paraspinal cancer. A cranial phantom was used to serve as a control. In all cases, CBCT images were acquired for patient setup with subsequent OB-2DkV verification. It was found that the accuracy of the 2D/3D registration was 0.0 ± 0.5 mm and 0.1° ± 0.4° in phantom. In patient, it is site dependent due to deformation of the anatomy: 0.2 ± 1.6 mm and −0.4° ± 1.2° on average for each dimension for the cranial site, 0.7 ± 1.6 mm and 0.3° ± 1.3° for HN, 0.7 ± 2.0 mm and −0.7° ± 1.1° for the thorax, and 1.1 ± 2.6 mm and −0.5° ± 1.9° for the abdomen. Anatomical deformation and presence of soft tissue in 2D/3D registration affect the consistency with 3D/3D registration in 6DOF: the discrepancy increases in superior to inferior direction. PMID:25223323

  9. Translational and rotational temperatures of a 2D vibrated granular gas in microgravity.

    PubMed

    Grasselli, Y; Bossis, G; Morini, R

    2015-02-01

    We present an experimental study performed on a vibrated granular gas enclosed into a 2D rectangular cell. Experiments are performed in microgravity conditions achieved during parabolic flights. High speed video recording and optical tracking allow to obtain the full kinematics (translation and rotation) of the particles. The inelastic parameters are retrieved from the experimental trajectories as well as the translational and rotational velocity distributions. We report that the experimental ratio of translational versus rotational temperature decreases with the density of the medium but increases with the driving velocity of the cell. These experimental results are compared with existing theories and we point out the differences observed. We also present a model which fairly predicts the equilibrium experimental temperatures along the direction of vibration. PMID:25681008

  10. Calibration and simulation of ASM2d at different temperatures in a phosphorus removal pilot plant.

    PubMed

    García-Usach, F; Ferrer, J; Bouzas, A; Seco, A

    2006-01-01

    In this work, an organic and nutrient removal pilot plant was used to study the temperature influence on phosphorus accumulating organisms. Three experiments were carried out at 13, 20 and 24.5 degrees C, achieving a high phosphorus removal percentage in all cases. The ASM2d model was calibrated at 13 and 20 degrees C and the Arrhenius equation constant was obtained for phosphorus removal processes showing that the temperature influences on the biological phosphorus removal subprocesses in a different degree. The 24.5 degrees C experiment was simulated using the model parameters obtained by means of the Arrhenius equation. The simulation results for the three experiments showed good correspondence with the experimental data, demonstrating that the model and the calibrated parameters were able to predict the pilot plant behaviour. PMID:16889256

  11. 3D/2D image registration using weighted histogram of gradient directions

    NASA Astrophysics Data System (ADS)

    Ghafurian, Soheil; Hacihaliloglu, Ilker; Metaxas, Dimitris N.; Tan, Virak; Li, Kang

    2015-03-01

    Three dimensional (3D) to two dimensional (2D) image registration is crucial in many medical applications such as image-guided evaluation of musculoskeletal disorders. One of the key problems is to estimate the 3D CT- reconstructed bone model positions (translation and rotation) which maximize the similarity between the digitally reconstructed radiographs (DRRs) and the 2D fluoroscopic images using a registration method. This problem is computational-intensive due to a large search space and the complicated DRR generation process. Also, finding a similarity measure which converges to the global optimum instead of local optima adds to the challenge. To circumvent these issues, most existing registration methods need a manual initialization, which requires user interaction and is prone to human error. In this paper, we introduce a novel feature-based registration method using the weighted histogram of gradient directions of images. This method simplifies the computation by searching the parameter space (rotation and translation) sequentially rather than simultaneously. In our numeric simulation experiments, the proposed registration algorithm was able to achieve sub-millimeter and sub-degree accuracies. Moreover, our method is robust to the initial guess. It can tolerate up to +/-90°rotation offset from the global optimal solution, which minimizes the need for human interaction to initialize the algorithm.

  12. 2D Imaging in a Lightweight Portable MRI Scanner without Gradient Coils

    PubMed Central

    Cooley, Clarissa Zimmerman; Stockmann, Jason P.; Armstrong, Brandon D.; Sarracanie, Mathieu; Lev, Michael H.; Rosen, Matthew S.; Wald, Lawrence L.

    2014-01-01

    Purpose As the premiere modality for brain imaging, MRI could find wider applicability if lightweight, portable systems were available for siting in unconventional locations such as Intensive Care Units, physician offices, surgical suites, ambulances, emergency rooms, sports facilities, or rural healthcare sites. Methods We construct and validate a truly portable (<100kg) and silent proof-of-concept MRI scanner which replaces conventional gradient encoding with a rotating lightweight cryogen-free, low-field magnet. When rotated about the object, the inhomogeneous field pattern is used as a rotating Spatial Encoding Magnetic field (rSEM) to create generalized projections which encode the iteratively reconstructed 2D image. Multiple receive channels are used to disambiguate the non-bijective encoding field. Results The system is validated with experimental images of 2D test phantoms. Similar to other non-linear field encoding schemes, the spatial resolution is position dependent with blurring in the center, but is shown to be likely sufficient for many medical applications. Conclusion The presented MRI scanner demonstrates the potential for portability by simultaneously relaxing the magnet homogeneity criteria and eliminating the gradient coil. This new architecture and encoding scheme shows convincing proof of concept images that are expected to be further improved with refinement of the calibration and methodology. PMID:24668520

  13. Designing of sparse 2D arrays for Lamb wave imaging using coarray concept

    SciTech Connect

    Ambroziński, Łukasz Stepinski, Tadeusz Uhl, Tadeusz

    2015-03-31

    2D ultrasonic arrays have considerable application potential in Lamb wave based SHM systems, since they enable equivocal damage imaging and even in some cases wave-mode selection. Recently, it has been shown that the 2D arrays can be used in SHM applications in a synthetic focusing (SF) mode, which is much more effective than the classical phase array mode commonly used in NDT. The SF mode assumes a single element excitation of subsequent transmitters and off-line processing the acquired data. In the simplest implementation of the technique, only single multiplexed input and output channels are required, which results in significant hardware simplification. Application of the SF mode for 2D arrays creates additional degrees of freedom during the design of the array topology, which complicates the array design process, however, it enables sparse array designs with performance similar to that of the fully populated dense arrays. In this paper we present the coarray concept to facilitate synthesis process of an array’s aperture used in the multistatic synthetic focusing approach in Lamb waves-based imaging systems. In the coherent imaging, performed in the transmit/receive mode, the sum coarray is a morphological convolution of the transmit/receive sub-arrays. It can be calculated as the set of sums of the individual sub-arrays’ elements locations. The coarray framework will be presented here using a an example of a star-shaped array. The approach will be discussed in terms of beampatterns of the resulting imaging systems. Both simulated and experimental results will be included.

  14. 2D and 3D visualization methods of endoscopic panoramic bladder images

    NASA Astrophysics Data System (ADS)

    Behrens, Alexander; Heisterklaus, Iris; Müller, Yannick; Stehle, Thomas; Gross, Sebastian; Aach, Til

    2011-03-01

    While several mosaicking algorithms have been developed to compose endoscopic images of the internal urinary bladder wall into panoramic images, the quantitative evaluation of these output images in terms of geometrical distortions have often not been discussed. However, the visualization of the distortion level is highly desired for an objective image-based medical diagnosis. Thus, we present in this paper a method to create quality maps from the characteristics of transformation parameters, which were applied to the endoscopic images during the registration process of the mosaicking algorithm. For a global first view impression, the quality maps are laid over the panoramic image and highlight image regions in pseudo-colors according to their local distortions. This illustration supports then surgeons to identify geometrically distorted structures easily in the panoramic image, which allow more objective medical interpretations of tumor tissue in shape and size. Aside from introducing quality maps in 2-D, we also discuss a visualization method to map panoramic images onto a 3-D spherical bladder model. Reference points are manually selected by the surgeon in the panoramic image and the 3-D model. Then the panoramic image is mapped by the Hammer-Aitoff equal-area projection onto the 3-D surface using texture mapping. Finally the textured bladder model can be freely moved in a virtual environment for inspection. Using a two-hemisphere bladder representation, references between panoramic image regions and their corresponding space coordinates within the bladder model are reconstructed. This additional spatial 3-D information thus assists the surgeon in navigation, documentation, as well as surgical planning.

  15. Room temperature weak ferromagnetism in Sn1-xMnxSe2 2D films grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Dong, Sining; Liu, Xinyu; Li, Xiang; Kanzyuba, Vasily; Yoo, Taehee; Rouvimov, Sergei; Vishwanath, Suresh; Xing, Huili G.; Jena, Debdeep; Dobrowolska, Margaret; Furdyna, Jacek K.

    2016-03-01

    We discuss growth and magnetic properties of high-quality two dimensional (2D) Sn1-xMnxSe2 films. Thin films of this 2D ternary alloy with a wide range of Mn concentrations were successfully grown by molecular beam epitaxy. Mn concentrations up to x ≈ 0.60 were achieved without destroying the crystal structure of the parent SnSe2 2D system. Most important, the specimens show clear weak ferromagnetic behavior above room temperature, which should be of interest for 2D spintronic applications.

  16. Photoacoustic imaging for deep targets in the breast using a multichannel 2D array transducer

    NASA Astrophysics Data System (ADS)

    Xie, Zhixing; Wang, Xueding; Morris, Richard F.; Padilla, Frederic R.; Lecarpentier, Gerald L.; Carson, Paul L.

    2011-03-01

    A photoacoustic (PA) imaging system was developed to achieve high sensitivity for the detection and characterization of vascular anomalies in the breast in the mammographic geometry. Signal detection from deep in the breast was achieved by a broadband 2D PVDF planar array that has a round shape with one side trimmed straight to improve fit near the chest wall. This array has 572 active elements and a -6dB bandwidth of 0.6-1.7 MHz. The low frequency enhances imaging depth and increases the size of vascular collections displayed without edge enhancement. The PA signals from all the elements go through low noise preamplifiers in the probe that are very close to the array elements for optimized noise control. Driven by 20 independent on-probe signal processing channels, imaging with both high sensitivity and good speed was achieved. To evaluate the imaging depth and the spatial resolution of this system,2.38mm I.D. artificial vessels embedded deeply in ex vivo breasts harvested from fresh cadavers and a 3mm I.D. tube in breast mimicking phantoms made of pork loin and fat tissues were imaged. Using near-infrared laser light with incident energy density within the ANSI safety limit, imaging depths of up to 49 mm in human breasts and 52 mm in phantoms were achieved. With a high power tunable laser working on multiple wavelengths, this system might contribute to 3D noninvasive imaging of morphological and physiological tissue features throughout the breast.

  17. 2D SAFT technique to reduce grating lobes in volumetric imaging

    NASA Astrophysics Data System (ADS)

    Martín, C. J.; Martínez, O.; Octavio, A.; Montero, F.; Ullate, L. G.

    2010-01-01

    Nowadays, ultrasonic imaging is widely accepted as a powerful tool for nondestructive evaluation in industrial and medical applications. Although its potential to provide volumetric images has been verified and there is a strong interest in the development of 3D system, it is an open question yet due to the large amount of required resources, the high volume of data under analysis, and the difficulty to design adequate sensors. This work is centered in the development of SAFT strategies for beamforming in 3D ultrasonic imaging systems based on a strong economy of resources in order to reduce complexity and cost, and improve the system portability. The use of synthetic aperture techniques (SAFT) to reduce the number of hardware channels has been a topic profusely studied in several application areas, such as radar, sonar or ultrasonic imaging. The conventional SAFT is based on the sequential activation, one by one, of the array elements in emission-reception. Once all the signals have been stored, the beamforming is applied in a post-processing stage, focusing every point in the image and correcting emission and reception simultaneously. SAFT images show higher lateral resolution than conventional phased array images, but unfortunately they also show grating lobes that reduce the contrast. Here we present a new SAFT technique for 2D arrays that eliminates the grating lobes making use of few resources. Thus, the technique requires no more than four reception channels in parallel for every emission. Experimental results are also presented to validate the simulations.

  18. A new fast method for the reconstruction of 2-D microwave images of rotating objects.

    PubMed

    Berizzi, F; Corsini, G

    1999-01-01

    In this paper, the problem of microwave imaging of rotating objects is approached from a digital signal processing point of view. Attention is focused on the reconstruction of the two-dimensional (2-D) image of an object obtained by processing complex samples of the continuous wave (CW) signal return received for different object aspect angles covering a 2pi total variation. The effects of a polar sampling of the Fourier transform (FT) of the target reflectivity function on the impulse response of the imaging system are analyzed. A criterion for the choice of the angular sampling interval in order to control the image blurring is given. Finally, a new and fast digital signal processing method for image reconstruction is proposed. This method reconstructs high resolution images of rotating targets illuminated by a CW electromagnetic signal or by a large bandwidth transmitted signal. This algorithm is suitable for processing wideband received signal of targets observed for a large variation of the viewing angle, so it is very attractive for the reconstruction of very high spatial resolution target images in SAR/ISAR systems. To show the performance of the method we finally present and discuss the results obtained by applying the proposed technique on simulated and experimental data. PMID:18267483

  19. GPU accelerated generation of digitally reconstructed radiographs for 2-D/3-D image registration.

    PubMed

    Dorgham, Osama M; Laycock, Stephen D; Fisher, Mark H

    2012-09-01

    Recent advances in programming languages for graphics processing units (GPUs) provide developers with a convenient way of implementing applications which can be executed on the CPU and GPU interchangeably. GPUs are becoming relatively cheap, powerful, and widely available hardware components, which can be used to perform intensive calculations. The last decade of hardware performance developments shows that GPU-based computation is progressing significantly faster than CPU-based computation, particularly if one considers the execution of highly parallelisable algorithms. Future predictions illustrate that this trend is likely to continue. In this paper, we introduce a way of accelerating 2-D/3-D image registration by developing a hybrid system which executes on the CPU and utilizes the GPU for parallelizing the generation of digitally reconstructed radiographs (DRRs). Based on the advancements of the GPU over the CPU, it is timely to exploit the benefits of many-core GPU technology by developing algorithms for DRR generation. Although some previous work has investigated the rendering of DRRs using the GPU, this paper investigates approximations which reduce the computational overhead while still maintaining a quality consistent with that needed for 2-D/3-D registration with sufficient accuracy to be clinically acceptable in certain applications of radiation oncology. Furthermore, by comparing implementations of 2-D/3-D registration on the CPU and GPU, we investigate current performance and propose an optimal framework for PC implementations addressing the rigid registration problem. Using this framework, we are able to render DRR images from a 256×256×133 CT volume in ~24 ms using an NVidia GeForce 8800 GTX and in ~2 ms using NVidia GeForce GTX 580. In addition to applications requiring fast automatic patient setup, these levels of performance suggest image-guided radiation therapy at video frame rates is technically feasible using relatively low cost PC architecture. PMID:22801484

  20. 2D surface temperature measurement of plasma facing components with modulated active pyrometry.

    PubMed

    Amiel, S; Loarer, T; Pocheau, C; Roche, H; Gauthier, E; Aumeunier, M-H; Le Niliot, C; Rigollet, F; Courtois, X; Jouve, M; Balorin, C; Moncada, V

    2014-10-01

    In nuclear fusion devices, such as Tore Supra, the plasma facing components (PFC) are in carbon. Such components are exposed to very high heat flux and the surface temperature measurement is mandatory for the safety of the device and also for efficient plasma scenario development. Besides this measurement is essential to evaluate these heat fluxes for a better knowledge of the physics of plasma-wall interaction, it is also required to monitor the fatigue of PFCs. Infrared system (IR) is used to manage to measure surface temperature in real time. For carbon PFCs, the emissivity is high and known (ɛ ∼ 0.8), therefore the contribution of the reflected flux from environment and collected by the IR cameras can be neglected. However, the future tokamaks such as WEST and ITER will be equipped with PFCs in metal (W and Be/W, respectively) with low and variable emissivities (ɛ ∼ 0.1-0.4). Consequently, the reflected flux will contribute significantly in the collected flux by IR camera. The modulated active pyrometry, using a bicolor camera, proposed in this paper allows a 2D surface temperature measurement independently of the reflected fluxes and the emissivity. Experimental results with Tungsten sample are reported and compared with simultaneous measurement performed with classical pyrometry (monochromatic and bichromatic) with and without reflective flux demonstrating the efficiency of this method for surface temperature measurement independently of the reflected flux and the emissivity. PMID:25362442

  1. 2D surface temperature measurement of plasma facing components with modulated active pyrometry

    SciTech Connect

    Amiel, S.; Loarer, T.; Pocheau, C.; Roche, H.; Gauthier, E.; Aumeunier, M.-H.; Courtois, X.; Jouve, M.; Balorin, C.; Moncada, V.; Le Niliot, C.; Rigollet, F.

    2014-10-01

    In nuclear fusion devices, such as Tore Supra, the plasma facing components (PFC) are in carbon. Such components are exposed to very high heat flux and the surface temperature measurement is mandatory for the safety of the device and also for efficient plasma scenario development. Besides this measurement is essential to evaluate these heat fluxes for a better knowledge of the physics of plasma-wall interaction, it is also required to monitor the fatigue of PFCs. Infrared system (IR) is used to manage to measure surface temperature in real time. For carbon PFCs, the emissivity is high and known (ε ~ 0.8), therefore the contribution of the reflected flux from environment and collected by the IR cameras can be neglected. However, the future tokamaks such as WEST and ITER will be equipped with PFCs in metal (W and Be/W, respectively) with low and variable emissivities (ε ~ 0.1–0.4). Consequently, the reflected flux will contribute significantly in the collected flux by IR camera. The modulated active pyrometry, using a bicolor camera, proposed in this paper allows a 2D surface temperature measurement independently of the reflected fluxes and the emissivity. Experimental results with Tungsten sample are reported and compared with simultaneous measurement performed with classical pyrometry (monochromatic and bichromatic) with and without reflective flux demonstrating the efficiency of this method for surface temperature measurement independently of the reflected flux and the emissivity.

  2. Temperature-Dependent Conformations of a Membrane Supported Zinc Porphyrin Tweezer by 2D Fluorescence Spectroscopy

    PubMed Central

    Widom, Julia R.; Lee, Wonbae; Perdomo-Ortiz, Alejandro; Rappoport, Dmitrij; Molinski, Tadeusz F.; Aspuru-Guzik, Aln; Marcus, Andrew H.

    2013-01-01

    We studied the equilibrium conformations of a zinc porphyrin tweezer composed of two carboxylphenyl-functionalized zinc tetraphenyl porphyrin subunits connected by a 1,4 butyndiol spacer, which was suspended inside the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) liposomes. By combining phase-modulation two-dimensional fluorescence spectroscopy (2D FS) with linear absorbance and fluorimetry, we determined that the zinc porphyrin tweezer adopts a mixture of folded and extended conformations in the membrane. By fitting an exciton-coupling model to a series of data sets recorded over a range of temperatures (17 85 C) and at different laser center wavelengths, we determined that the folded form of the tweezer is stabilized by a favorable change in the entropy of the local membrane environment. Our results provide insights toward understanding the balance of thermodynamic factors that govern molecular assembly in membranes. PMID:23480874

  3. Visualizing 3D Objects from 2D Cross Sectional Images Displayed "In-Situ" versus "Ex-Situ"

    ERIC Educational Resources Information Center

    Wu, Bing; Klatzky, Roberta L.; Stetten, George

    2010-01-01

    The present research investigates how mental visualization of a 3D object from 2D cross sectional images is influenced by displacing the images from the source object, as is customary in medical imaging. Three experiments were conducted to assess people's ability to integrate spatial information over a series of cross sectional images in order to…

  4. Visualizing 3D Objects from 2D Cross Sectional Images Displayed "In-Situ" versus "Ex-Situ"

    ERIC Educational Resources Information Center

    Wu, Bing; Klatzky, Roberta L.; Stetten, George

    2010-01-01

    The present research investigates how mental visualization of a 3D object from 2D cross sectional images is influenced by displacing the images from the source object, as is customary in medical imaging. Three experiments were conducted to assess people's ability to integrate spatial information over a series of cross sectional images in order to

  5. Enhanced detection of the vertebrae in 2D CT-images

    NASA Astrophysics Data System (ADS)

    Graf, Franz; Greil, Robert; Kriegel, Hans-Peter; Schubert, Matthias; Cavallaro, Alexander

    2012-02-01

    In recent years, a considerable amount of methods have been proposed for detecting and reconstructing the spine and the vertebrae from CT and MR scans. The results are either used for examining the vertebrae or serve as a preprocessing step for further detection and annotation tasks. In this paper, we propose a method for reliably detecting the position of the vertebrae on a single slice of a transversal body CT scan. Thus, our method is not restricted by the available portion of the 3D scan, but even suffices with a single 2D image. A further advantage of our method is that detection does not require adjusting parameters or direct user interaction. Technically, our method is based on an imaging pipeline comprising five steps: The input image is preprocessed. The relevant region of the image is extracted. Then, a set of candidate locations is selected based on bone density. In the next step, image features are extracted from the surrounding of the candidate locations and an instance-based learning approach is used for selecting the best candidate. Finally, a refinement step optimizes the best candidate region. Our proposed method is validated on a large diverse data set of more than 8 000 images and improves the accuracy in terms of area overlap and distance from the true position significantly compared to the only other method being proposed for this task so far.

  6. Beamforming of Ultrasound Signals from 1-D and 2-D Arrays under Challenging Imaging Conditions

    NASA Astrophysics Data System (ADS)

    Jakovljevic, Marko

    Beamforming of ultrasound signals in the presence of clutter, or partial aperture blockage by an acoustic obstacle can lead to reduced visibility of the structures of interest and diminished diagnostic value of the resulting image. We propose new beamforming methods to recover the quality of ultrasound images under such challenging conditions. Of special interest are the signals from large apertures, which are more susceptible to partial blockage, and from commercial matrix arrays that suffer from low sensitivity due to inherent design/hardware limitations. A coherence-based beamforming method designed for suppressing the in vivo clutter, namely Short-lag Spatial Coherence (SLSC) Imaging, is first implemented on a 1-D array to enhance visualization of liver vasculature in 17 human subjects. The SLSC images show statistically significant improvements in vessel contrast and contrast-to-noise ratio over the matched B-mode images. The concept of SLSC imaging is then extended to matrix arrays, and the first in vivo demonstration of volumetric SLSC imaging on a clinical ultrasound system is presented. The effective suppression of clutter via volumetric SLSC imaging indicates it could potentially compensate for the low sensitivity associated with most commercial matrix arrays. The rest of the dissertation assesses image degradation due to elements blocked by ribs in a transthoracic scan. A method to detect the blocked elements is demonstrated using simulated, ex vivo, and in vivo data from the fully-sampled 2-D apertures. The results show that turning off the blocked elements both reduces the near-field clutter and improves visibility of anechoic/hypoechoic targets. Most importantly, the ex vivo data from large synthetic apertures indicates that the adaptive weighing of the non-blocked elements can recover the loss of focus quality due to periodic rib structure, allowing large apertures to realize their full resolution potential in transthoracic ultrasound.

  7. Plane-wave transverse oscillation for high-frame-rate 2-D vector flow imaging.

    PubMed

    Lenge, Matteo; Ramalli, Alessandro; Tortoli, Piero; Cachard, Christian; Liebgott, Hervé

    2015-12-01

    Transverse oscillation (TO) methods introduce oscillations in the pulse-echo field (PEF) along the direction transverse to the ultrasound propagation direction. This may be exploited to extend flow investigations toward multidimensional estimates. In this paper, the TOs are coupled with the transmission of plane waves (PWs) to reconstruct high-framerate RF images with bidirectional oscillations in the pulse-echo field. Such RF images are then processed by a 2-D phase-based displacement estimator to produce 2-D vector flow maps at thousands of frames per second. First, the capability of generating TOs after PW transmissions was thoroughly investigated by varying the lateral wavelength, the burst length, and the transmission frequency. Over the entire region of interest, the generated lateral wavelengths, compared with the designed ones, presented bias and standard deviation of -3.3 ± 5.7% and 10.6 ± 7.4% in simulations and experiments, respectively. The performance of the ultrafast vector flow mapping method was also assessed by evaluating the differences between the estimated velocities and the expected ones. Both simulations and experiments show overall biases lower than 20% when varying the beam-to-flow angle, the peak velocity, and the depth of interest. In vivo applications of the method on the common carotid and the brachial arteries are also presented. PMID:26670852

  8. Aortic root 3D parametric morphological model from 2D-echo images.

    PubMed

    Morganti, Simone; Valentini, Adele; Favalli, Valentina; Serio, Alessandra; Gambarin, Fabiana I; Vella, Danila; Mazzocchi, Laura; Massetti, Massimo; Auricchio, Ferdinando; Arbustini, Eloisa

    2013-12-01

    The gold standard for the study of the macro-anatomy of the aortic root are multi-detector computed tomography (MDCT) and magnetic resonance (MR) imaging. Both technologies have major advantages and limitations. Although 4D echo is entering the study of the aortic root, 2D echo is the most commonly used diagnostic tool in daily practice. We designed and developed an algorithm for 3D modeling of the aortic root based on measures taken routinely at 2D echocardiography from 20 healthy individuals with normal aortic root. The tool was then translated in 12 patients who underwent both echo and MDCT. The results obtained with the 3D modeling program were quantitatively and qualitatively compared with 3D reconstruction from MDCT. Ad hoc ratios describing the morphology of the aortic root in MDCT and in the 3D model were used for comparison. In 12 patients with aortic root dilatation, the ratios obtained with our model are in good agreement with those from MDCT. Linear correlation for both long axis and short axis ratios was strong. The 3D modeling software can be easily adopted by cardiologists routinely involved in clinical evaluation of the pathology of the aortic root. The tool is easy to apply, does not require additional costs, and may be used to generate a set of data images for monitoring the evolution of the morphology and dimension of the aortic root, flanking the 3D MDCT and MR that remain the gold standard tools. PMID:24290936

  9. Non-rigid 2D-3D medical image registration using markov random fields.

    PubMed

    Ferrante, Enzo; Paragios, Nikos

    2013-01-01

    The aim of this paper is to propose a novel mapping algorithm between 2D images and a 3D volume seeking simultaneously a linear plane transformation and an in-plane dense deformation. We adopt a metric free locally over-parametrized graphical model that combines linear and deformable parameters within a coupled formulation on a 5-dimensional space. Image similarity is encoded in singleton terms, while geometric linear consistency of the solution (common/single plane) and in-plane deformations smoothness are modeled in a pair-wise term. The robustness of the method and its promising results with respect to the state of the art demonstrate the extreme potential of this approach. PMID:24505757

  10. 2-D Registration and 3-D Shape Inference of the Retinal Fundus from Fluorescein Images

    PubMed Central

    Choe, Tae Eun; Medioni, Gerard; Cohen, Isaac; Walsh, Alexander C.; Sadda, SriniVas R.

    2008-01-01

    This study presents methods to 2-D registration of retinal image sequences and 3-D shape inference from fluorescein images. The Y-feature is a robust geometric entity that is largely invariant across modalities as well as across the temporal grey level variations induced by the propagation of the dye in the vessels. We first present a Y-feature extraction method that finds a set of Y-feature candidates using local image gradient information. A gradient-based approach is then used to align an articulated model of the Y-feature to the candidates more accurately while optimizing a cost function. Using mutual information, fitted Y-features are subsequently matched across images, including colors and fluorescein angiographic frames, for registration. To reconstruct the retinal fundus in 3-D, the extracted Y-features are used to estimate the epipolar geometry with a plane-and-parallax approach. The proposed solution provides a robust estimation of the fundamental matrix suitable for plane-like surfaces, such as the retinal fundus. The mutual information criterion is used to accurately estimate the dense disparity map, while the Y-features are used to estimate the bounds of the range space. Our experimental results validate the proposed method on a set of difficult fluorescein image pairs. PMID:18060827

  11. 2-D Gaussian beam imaging of multicomponent seismic data in anisotropic media

    NASA Astrophysics Data System (ADS)

    Protasov, M. I.

    2015-12-01

    An approach for true-amplitude seismic beam imaging of multicomponent seismic data in 2-D anisotropic elastic media is presented and discussed. Here, the recovered true-amplitude function is a scattering potential. This approach is a migration procedure based on the weighted summation of pre-stack data. The true-amplitude weights are computed by applying Gaussian beams (GBs). We shoot a pair of properly chosen GBs with a fixed dip and opening angles from the current imaging point towards an acquisition system. This pair of beams is used to compute a true-amplitude selective image of a rapid velocity variation. The total true-amplitude image is constructed by superimposing selective images computed for a range of available dip angles. The global regularity of the GBs allows one to disregard whether a ray field is regular or irregular. P- and S-wave GBs can be used to handle raw multicomponent data without separating the waves. The use of anisotropic GBs allows one to take into account the anisotropy of the background model.

  12. Constructing a Database from Multiple 2D Images for Camera Pose Estimation and Robot Localization

    NASA Technical Reports Server (NTRS)

    Wolf, Michael; Ansar, Adnan I.; Brennan, Shane; Clouse, Daniel S.; Padgett, Curtis W.

    2012-01-01

    The LMDB (Landmark Database) Builder software identifies persistent image features (landmarks) in a scene viewed multiple times and precisely estimates the landmarks 3D world positions. The software receives as input multiple 2D images of approximately the same scene, along with an initial guess of the camera poses for each image, and a table of features matched pair-wise in each frame. LMDB Builder aggregates landmarks across an arbitrarily large collection of frames with matched features. Range data from stereo vision processing can also be passed to improve the initial guess of the 3D point estimates. The LMDB Builder aggregates feature lists across all frames, manages the process to promote selected features to landmarks, and iteratively calculates the 3D landmark positions using the current camera pose estimations (via an optimal ray projection method), and then improves the camera pose estimates using the 3D landmark positions. Finally, it extracts image patches for each landmark from auto-selected key frames and constructs the landmark database. The landmark database can then be used to estimate future camera poses (and therefore localize a robotic vehicle that may be carrying the cameras) by matching current imagery to landmark database image patches and using the known 3D landmark positions to estimate the current pose.

  13. A temperature dependent 2D-ACAR study of untwinned metallic YBa 2Cu 3O 7- x

    NASA Astrophysics Data System (ADS)

    Smedskjaer, L. C.; Bansil, A.; Welp, U.; Fang, Y.; Bailey, K. G.

    1992-03-01

    We have carried out 2D-ACAR measurements in the c-axis projection on an untwinned single crystal of YBa 2Cu 3O 7- x as a function of temperature, for five temperatures ranging from 30 K to 300 K. These temperature dependent 2D-ACAR spectra can be approximated by a superposition of two temperature independent spectra with temperature dependent weighting factors. We discuss how the temperature dependence of the data can be exploited to obtain a “background corrected” experimental spectrum, which is found to be in remarkable accord with the corresponding band theory based predictions, including for the first time the overall amplitude of the anisotropy in the 2D-ACAR. The corrected data also shows clear signatures of the ridge Fermi surface and an indication of the pillbox surface.

  14. Rotationally symmetric triangulation sensor with integrated object imaging using only one 2D detector

    NASA Astrophysics Data System (ADS)

    Eckstein, Johannes; Lei, Wang; Becker, Jonathan; Jun, Gao; Ott, Peter

    2006-04-01

    In this paper a distance measurement sensor is introduced, equipped with two integrated optical systems, the first one for rotationally symmetric triangulation and the second one for imaging the object while using only one 2D detector for both purposes. Rotationally symmetric triangulation, introduced in [1], eliminates some disadvantages of classical triangulation sensors, especially at steps or strong curvatures of the object, wherefore the measurement result depends not any longer on the angular orientation of the sensor. This is achieved by imaging the scattered light from an illuminated object point to a centered and sharp ring on a low cost area detector. The diameter of the ring is proportional to the distance of the object. The optical system consists of two off axis aspheric reflecting surfaces. This system allows for integrating a second optical system in order to capture images of the object at the same 2D detector. A mock-up was realized for the first time which consists of the reflecting optics for triangulation manufactured by diamond turning. A commercially available appropriate small lens system for imaging was mechanically integrated in the reflecting optics. Alternatively, some designs of retrofocus lens system for larger field of views were investigated. The optical designs allow overlying the image of the object and the ring for distance measurement in the same plane. In this plane a CCD detector is mounted, centered to the optical axis for both channels. A fast algorithm for the evaluation of the ring is implemented. The characteristics, i.e. the ring diameter versus object distance shows very linear behavior. For illumination of the object point for distance measurement, the beam of a red laser diode system is reflected by a wavelength bandpath filter on the axis of the optical system in. Additionally, the surface of the object is illuminated by LED's in the green spectrum. The LED's are located on the outside rim of the reflecting optics. The scattered LED light is transmitted by the before mentioned bandpath filter and is captured by the imaging lens. A simultaneous mode, in which the ring for distance measurement is superimposed to the image of the object, and a time multiplexing mode were implemented thus demonstrating the flexibility and performance options of this approach.

  15. Proposal to Construct a 3D Image Viewer Based on a Commercial Ultrasonic 2D Imaging System

    NASA Astrophysics Data System (ADS)

    Arce, F.; Leija, L.; Vera, A.; Sossa, H.

    This paper describes an approach to develop a procedure to reconstruct 3D volumes of breast cancer by using 2D ultrasonic (US) images in order to provide the shape and the dimensions of the cancer. We obtained 91.66% accuracy in the 3D reconstruction process. Breast and breast cancer phantoms were made in order to mimic acoustic properties (speed propagation). The US images of the phantoms were taken with commercial US equipment (Prosound 6, Aloka) by using a convex transducer probe (3-6 MHz and 82 scanning angle), which was moved with a mechanical positioner with a resolution of 0.1 mm.

  16. 2D Seismic Imaging of Elastic Parameters by Frequency Domain Full Waveform Inversion

    NASA Astrophysics Data System (ADS)

    Brossier, R.; Virieux, J.; Operto, S.

    2008-12-01

    Thanks to recent advances in parallel computing, full waveform inversion is today a tractable seismic imaging method to reconstruct physical parameters of the earth interior at different scales ranging from the near- surface to the deep crust. We present a massively parallel 2D frequency-domain full-waveform algorithm for imaging visco-elastic media from multi-component seismic data. The forward problem (i.e. the resolution of the frequency-domain 2D PSV elastodynamics equations) is based on low-order Discontinuous Galerkin (DG) method (P0 and/or P1 interpolations). Thanks to triangular unstructured meshes, the DG method allows accurate modeling of both body waves and surface waves in case of complex topography for a discretization of 10 to 15 cells per shear wavelength. The frequency-domain DG system is solved efficiently for multiple sources with the parallel direct solver MUMPS. The local inversion procedure (i.e. minimization of residuals between observed and computed data) is based on the adjoint-state method which allows to efficiently compute the gradient of the objective function. Applying the inversion hierarchically from the low frequencies to the higher ones defines a multiresolution imaging strategy which helps convergence towards the global minimum. In place of expensive Newton algorithm, the combined use of the diagonal terms of the approximate Hessian matrix and optimization algorithms based on quasi-Newton methods (Conjugate Gradient, LBFGS, ...) allows to improve the convergence of the iterative inversion. The distribution of forward problem solutions over processors driven by a mesh partitioning performed by METIS allows to apply most of the inversion in parallel. We shall present the main features of the parallel modeling/inversion algorithm, assess its scalability and illustrate its performances with realistic synthetic case studies.

  17. 2D Thermoluminescence imaging of dielectric surface long term charge memory of plasma surface interaction in DBD discharges

    NASA Astrophysics Data System (ADS)

    Ambrico, Paolo F.; Ambrico, Marianna; Schiavulli, Luigi; De Benedictis, Santolo

    2014-07-01

    The charge trapping effect due to the exposure of alumina surfaces to plasma has been studied in a volume dielectric barrier discharge (DBD) in Ar and He noble gases. The long lasting charge trapping of alumina dielectric plates, used as barriers in DBDs, is evidenced by an ex situ thermoluminescence (TL) experiment performed with a standard and a custom two-dimensional (2D)-TL apparatus. The spatial density of trapped surface charges is found to be strongly correlated to the plasma morphology, and the surface spatial memory lasted for several minutes to hours after plasma exposure. In the case of Ar, the plasma channel impact signature on the surface shows a higher equivalent radiation dose with respect to the surface plasma wave and the post-discharge species signature. As a consequence, for the development of discharges, inside the dielectric surface the availability of lower energy trapped electrons is larger in the first region of plasma impact. The reported spatial memory increases the likelihood of the occurrence of plasma filaments in the same position in different runs. In He plasmas, the dielectric barrier shows an almost uniform distribution of trapped charges, meaning that there is no preferred region for the development of the discharge. In all cases a slight asymmetry was shown in the direction of the gas flow. This can be interpreted as being due to the long-living species moving in the direction of the gas flow, corresponding with the TL side experiment on the sample exposed to the plasma afterglow. The maximum values and the integral of the 2D-TL images showed a linear relation with the total charge per ac cycle, corresponding with findings for the TL glow curve. In conclusion, 2D-TL images allow the retrieval of information regarding the plasma surface interaction such as the plasma morphology, trap sites and their activation temperature.

  18. Embedded morphological dilation coding for 2D and 3D images

    NASA Astrophysics Data System (ADS)

    Lazzaroni, Fabio; Signoroni, Alberto; Leonardi, Riccardo

    2002-01-01

    Current wavelet-based image coders obtain high performance thanks to the identification and the exploitation of the statistical properties of natural images in the transformed domain. Zerotree-based algorithms, as Embedded Zerotree Wavelets (EZW) and Set Partitioning In Hierarchical Trees (SPIHT), offer high Rate-Distortion (RD) coding performance and low computational complexity by exploiting statistical dependencies among insignificant coefficients on hierarchical subband structures. Another possible approach tries to predict the clusters of significant coefficients by means of some form of morphological dilation. An example of a morphology-based coder is the Significance-Linked Connected Component Analysis (SLCCA) that has shown performance which are comparable to the zerotree-based coders but is not embedded. A new embedded bit-plane coder is proposed here based on morphological dilation of significant coefficients and context based arithmetic coding. The algorithm is able to exploit both intra-band and inter-band statistical dependencies among wavelet significant coefficients. Moreover, the same approach is used both for two and three-dimensional wavelet-based image compression. Finally we the algorithms are tested on some 2D images and on a medical volume, by comparing the RD results to those obtained with the state-of-the-art wavelet-based coders.

  19. Elemental 2D imaging of paintings with a mobile EDXRF system.

    PubMed

    Hocquet, François-Philippe; Calvo del Castillo, Helena; Cervera Xicotencatl, Ariadna; Bourgeois, Catherine; Oger, Cécile; Marchal, André; Clar, Mathieu; Rakkaa, Saïd; Micha, Edith; Strivay, David

    2011-03-01

    Imaging techniques are now used commonly and intensively in cultural heritage object analysis. Nowadays, many different techniques in nature as well as many applications exist, where they can be applied. X-ray radiography and infrared reflectography as well as UV photography are some of the most applied techniques. The study of works of art usually requires these techniques to be non-invasive. Furthermore, they are frequently required to perform in situ analysis. A few years ago, our laboratory developed a mobile energy-dispersive X-ray fluorescence and UV-vis-NIR coupled spectrometer, especially designed for fieldwork studies, where all three techniques can be applied strictly at the same site of analysis. Recent developments on a new positioning system have now allowed us to perform 2D elemental mappings with our equipment, which is especially well adapted to painting analysis. The system control is carried out entirely through a laptop computer running a dedicated homemade software. The positioning is achieved by means of a CCD camera embedded in the system and controlled via a Wi-Fi connection through the computer. The data acquisition system, which is made through a homemade multichannel pulse height analyzer, being also managed via the software mentioned above, goes through an Ethernet connection. We will present here the new developments of the system and an example of in situ 2D elemental mapping applied on an anonymous oil painting on wood panel. The discovery of a hidden painting under this oil painting makes it a good choice for a first example of 2D large scan with a mobile instrument. PMID:20953768

  20. 2D photoacoustic scanning imaging with a single pulsed laser diode excitation

    NASA Astrophysics Data System (ADS)

    Chen, Xuegang; Li, Changwei; Zeng, Lvming; Liu, Guodong; Huang, Zhen; Ren, Zhong

    2012-03-01

    A portable near-infrared photoacoustic scanning imaging system has been developed with a single pulsed laser diode, which was integrated with an optical lens system to straightforward boost the laser energy density for photoacoustic generation. The 905 nm laser diode provides a maximum energy output of 14 μJ within 100 ns pulse duration, and the pulse repetition frequency rate is 0.8 KHz. As a possible alternative light source, the preliminary 2D photoacoustic results primely correspond with the test phantoms of umbonate extravasated gore and knotted blood vessel network. The photoacoustic SNR can reach 20.6+/-1.2 dB while signal averaging reduces to 128 pulses from thousands to tens of thousands times, and the signal acquisition time accelerates to less than 0.2 s in each A-scan, especially the volume of the total radiation source is only 10 × 3 × 3 cm3. It demonstrated that the pulsed semiconductor laser could be a candidate of photoacoustic equipment for daily clinical application.

  1. 2D photoacoustic scanning imaging with a single pulsed laser diode excitation

    NASA Astrophysics Data System (ADS)

    Chen, Xuegang; Li, Changwei; Zeng, Lvming; Liu, Guodong; Huang, Zhen; Ren, Zhong

    2011-11-01

    A portable near-infrared photoacoustic scanning imaging system has been developed with a single pulsed laser diode, which was integrated with an optical lens system to straightforward boost the laser energy density for photoacoustic generation. The 905 nm laser diode provides a maximum energy output of 14 μJ within 100 ns pulse duration, and the pulse repetition frequency rate is 0.8 KHz. As a possible alternative light source, the preliminary 2D photoacoustic results primely correspond with the test phantoms of umbonate extravasated gore and knotted blood vessel network. The photoacoustic SNR can reach 20.6+/-1.2 dB while signal averaging reduces to 128 pulses from thousands to tens of thousands times, and the signal acquisition time accelerates to less than 0.2 s in each A-scan, especially the volume of the total radiation source is only 10 × 3 × 3 cm3. It demonstrated that the pulsed semiconductor laser could be a candidate of photoacoustic equipment for daily clinical application.

  2. A 2D to 3D ultrasound image registration algorithm for robotically assisted laparoscopic radical prostatectomy

    NASA Astrophysics Data System (ADS)

    Esteghamatian, Mehdi; Pautler, Stephen E.; McKenzie, Charles A.; Peters, Terry M.

    2011-03-01

    Robotically assisted laparoscopic radical prostatectomy (RARP) is an effective approach to resect the diseased organ, with stereoscopic views of the targeted tissue improving the dexterity of the surgeons. However, since the laparoscopic view acquires only the surface image of the tissue, the underlying distribution of the cancer within the organ is not observed, making it difficult to make informed decisions on surgical margins and sparing of neurovascular bundles. One option to address this problem is to exploit registration to integrate the laparoscopic view with images of pre-operatively acquired dynamic contrast enhanced (DCE) MRI that can demonstrate the regions of malignant tissue within the prostate. Such a view potentially allows the surgeon to visualize the location of the malignancy with respect to the surrounding neurovascular structures, permitting a tissue-sparing strategy to be formulated directly based on the observed tumour distribution. If the tumour is close to the capsule, it may be determined that the adjacent neurovascular bundle (NVB) needs to be sacrificed within the surgical margin to ensure that any erupted tumour was resected. On the other hand, if the cancer is sufficiently far from the capsule, one or both NVBs may be spared. However, in order to realize such image integration, the pre-operative image needs to be fused with the laparoscopic view of the prostate. During the initial stages of the operation, the prostate must be tracked in real time so that the pre-operative MR image remains aligned with patient coordinate system. In this study, we propose and investigate a novel 2D to 3D ultrasound image registration algorithm to track the prostate motion with an accuracy of 2.68+/-1.31mm.

  3. 3D prostate boundary segmentation from ultrasound images using 2D active shape models.

    PubMed

    Hodge, Adam C; Ladak, Hanif M

    2006-01-01

    Boundary outlining, or segmentation, of the prostate is an important task in diagnosis and treatment planning for prostate cancer. This paper describes an algorithm for semi-automatic, three-dimensional (3D) segmentation of the prostate boundary from ultrasound images based on two-dimensional (2D) active shape models (ASM) and rotation-based slicing. Evaluation of the algorithm used distance- and volume-based error metrics to compare algorithm generated boundary outlines to gold standard (manually generated) boundary outlines. The mean absolute distance between the algorithm and gold standard boundaries was 1.09+/-0.49 mm, the average percent absolute volume difference was 3.28+/-3.16%, and a 5x speed increase as compared manual planimetry was achieved. PMID:17946106

  4. Comparison of 2D temperature maps recorded during laser-induced thermal tissue treatment with corresponding temperature distributions calculated from 3D Monte-Carlo simulations

    NASA Astrophysics Data System (ADS)

    Busse, Harald; Bublat, Martin; Ratering, Ralf; Rassek, Margarethe; Schwarzmaier, Hans-Joachim; Kahn, Thomas

    2000-05-01

    Minimally invasive techniques often require special biomedical monitoring schemes. In the case of laser coagulation of tumors accurate temperature mapping is desirable for therapy control. While magnetic resonance (MR)-based thermometry can easily yield qualitative results it is still difficult to calibrate this technique with independent temperature probes for the entire 2D field of view. Calculated temperature maps derived from Monte-Carlo simulations (MCS), on the other hand, are suitable for therapy planning and dosimetry but typically can not account for the extract individual tissue parameters and physiological changes upon heating. In this work, online thermometry was combined with MCS techniques to explore the feasibility and potential of such a biomodal approach for surgical assist systems. For the first time, the result of a 3D simulation were evaluated with MR techniques. An MR thermometry system was used to monitor the temperature evolution during laser-induced thermal treatment of bovine liver using a commercially available water-cooled applicator. A systematic comparison between MR-derived 2D temperature maps in different orientations and corresponding snapshots of a 3D MCS of the laser-induced processes is presented. The MCS is capable of resolving the complex temperature patterns observed in the MR-derived images and yields a good agreement with respect to absolute temperatures and damage volume dimensions. The observed quantitative agreement is around 10 degrees C and on the order of 10 percent, respectively. The integrated simulation-and-monitoring approach has the potential to improve surgical assistance during thermal interventions.

  5. Automatic ultrasound image enhancement for 2D semi-automatic breast-lesion segmentation

    NASA Astrophysics Data System (ADS)

    Lu, Kongkuo; Hall, Christopher S.

    2014-03-01

    Breast cancer is the fastest growing cancer, accounting for 29%, of new cases in 2012, and second leading cause of cancer death among women in the United States and worldwide. Ultrasound (US) has been used as an indispensable tool for breast cancer detection/diagnosis and treatment. In computer-aided assistance, lesion segmentation is a preliminary but vital step, but the task is quite challenging in US images, due to imaging artifacts that complicate detection and measurement of the suspect lesions. The lesions usually present with poor boundary features and vary significantly in size, shape, and intensity distribution between cases. Automatic methods are highly application dependent while manual tracing methods are extremely time consuming and have a great deal of intra- and inter- observer variability. Semi-automatic approaches are designed to counterbalance the advantage and drawbacks of the automatic and manual methods. However, considerable user interaction might be necessary to ensure reasonable segmentation for a wide range of lesions. This work proposes an automatic enhancement approach to improve the boundary searching ability of the live wire method to reduce necessary user interaction while keeping the segmentation performance. Based on the results of segmentation of 50 2D breast lesions in US images, less user interaction is required to achieve desired accuracy, i.e. < 80%, when auto-enhancement is applied for live-wire segmentation.

  6. Extending Ripley’s K-Function to Quantify Aggregation in 2-D Grayscale Images

    PubMed Central

    Amgad, Mohamed; Itoh, Anri; Tsui, Marco Man Kin

    2015-01-01

    In this work, we describe the extension of Ripley’s K-function to allow for overlapping events at very high event densities. We show that problematic edge effects introduce significant bias to the function at very high densities and small radii, and propose a simple correction method that successfully restores the function’s centralization. Using simulations of homogeneous Poisson distributions of events, as well as simulations of event clustering under different conditions, we investigate various aspects of the function, including its shape-dependence and correspondence between true cluster radius and radius at which the K-function is maximized. Furthermore, we validate the utility of the function in quantifying clustering in 2-D grayscale images using three modalities: (i) Simulations of particle clustering; (ii) Experimental co-expression of soluble and diffuse protein at varying ratios; (iii) Quantifying chromatin clustering in the nuclei of wt and crwn1 crwn2 mutant Arabidopsis plant cells, using a previously-published image dataset. Overall, our work shows that Ripley’s K-function is a valid abstract statistical measure whose utility extends beyond the quantification of clustering of non-overlapping events. Potential benefits of this work include the quantification of protein and chromatin aggregation in fluorescent microscopic images. Furthermore, this function has the potential to become one of various abstract texture descriptors that are utilized in computer-assisted diagnostics in anatomic pathology and diagnostic radiology. PMID:26636680

  7. Imaging spectrophotometer for 2D spatially resolved measurements of spectral reflectance of materials

    NASA Astrophysics Data System (ADS)

    Mahmoud, Khaled; Park, Seongchong; Park, Seung-Nam; Lee, Dong-Hoon

    2015-07-01

    We introduce a new prototype instrument for measuring the 2D spatially resolved distribution of spectral reflectance based on new spectral imaging technique. The instrument captures digital spectral images of a test sample using a pulsed LED-based monochromatic source and a scientific grade CCD array and special data acquisition algorithm is used to extract the useful image data corresponding to the target application. In earlier version of this instrument, we used a commercial CCD camera with 8-bit ADC without any cooling stages which has many drawbacks. In this work, we have modified our setup by introducing a new scientific grade CCD; deep-cooled interline transfer sensor with 16-bit ADC and electronic shutter. With this new instrument we could achieve a higher accuracy, higher spatially resolved measurements, higher dynamic range, mush better sensitivity and lower uncertainty and we could avoid many sources of errors in the old setup. With one wavelength scan, one can get the full reflectance data of the sample under test which saves a lot of time in comparison with conventional methods. This new instrument is promising with a potential of applications in the field of optical material testing.

  8. Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media

    NASA Technical Reports Server (NTRS)

    Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Liu, Feng (Inventor); Lax, Melvin (Inventor); Das, Bidyut B. (Inventor)

    1999-01-01

    A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: ##EQU1## wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =/<.DELTA.Xj.DELTA.Xj> Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absoption information. An algorithm, which combines a two dimensional (2D) matrix inversion with a one-dimensional (1D) Fourier transform inversion is used to obtain images of three dimensional hidden objects in turbid scattering media.

  9. Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media

    NASA Technical Reports Server (NTRS)

    Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Gayen, Swapan K. (Inventor)

    2000-01-01

    A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =/<.DELTA.Xj.DELTA.Xj> Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absorption information. An algorithm, which combines a two dimensional (2D) matrix inversion with a one-dimensional (1D) Fourier transform inversion is used to obtain images of three dimensional hidden objects in turbid scattering media.

  10. Model-based segmentation and quantification of subcellular structures in 2D and 3D fluorescent microscopy images

    NASA Astrophysics Data System (ADS)

    Wörz, Stefan; Heinzer, Stephan; Weiss, Matthias; Rohr, Karl

    2008-03-01

    We introduce a model-based approach for segmenting and quantifying GFP-tagged subcellular structures of the Golgi apparatus in 2D and 3D microscopy images. The approach is based on 2D and 3D intensity models, which are directly fitted to an image within 2D circular or 3D spherical regions-of-interest (ROIs). We also propose automatic approaches for the detection of candidates, for the initialization of the model parameters, and for adapting the size of the ROI used for model fitting. Based on the fitting results, we determine statistical information about the spatial distribution and the total amount of intensity (fluorescence) of the subcellular structures. We demonstrate the applicability of our new approach based on 2D and 3D microscopy images.

  11. Optimal interlayer hopping and high temperature Bose-Einstein condensation of local pairs in quasi 2D superconductors.

    PubMed

    Kornilovitch, P E; Hague, J P

    2015-02-25

    Both FeSe and cuprate superconductors are quasi 2D materials with high transition temperatures and local fermion pairs. Motivated by such systems, we investigate real space pairing of fermions in an anisotropic lattice model with intersite attraction, V, and strong local Coulomb repulsion, U, leading to a determination of the optimal conditions for superconductivity from Bose-Einstein condensation. Our aim is to gain insight as to why high temperature superconductors tend to be quasi 2D. We make both analytically and numerically exact solutions for two body local pairing applicable to intermediate and strong V. We find that the Bose-Einstein condensation temperature of such local pairs pairs is maximal when hopping between layers is intermediate relative to in-plane hopping, indicating that the quasi 2D nature of unconventional superconductors has an important contribution to their high transition temperatures. PMID:25629425

  12. Web-based interactive 2D/3D medical image processing and visualization software.

    PubMed

    Mahmoudi, Seyyed Ehsan; Akhondi-Asl, Alireza; Rahmani, Roohollah; Faghih-Roohi, Shahrooz; Taimouri, Vahid; Sabouri, Ahmad; Soltanian-Zadeh, Hamid

    2010-05-01

    There are many medical image processing software tools available for research and diagnosis purposes. However, most of these tools are available only as local applications. This limits the accessibility of the software to a specific machine, and thus the data and processing power of that application are not available to other workstations. Further, there are operating system and processing power limitations which prevent such applications from running on every type of workstation. By developing web-based tools, it is possible for users to access the medical image processing functionalities wherever the internet is available. In this paper, we introduce a pure web-based, interactive, extendable, 2D and 3D medical image processing and visualization application that requires no client installation. Our software uses a four-layered design consisting of an algorithm layer, web-user-interface layer, server communication layer, and wrapper layer. To compete with extendibility of the current local medical image processing software, each layer is highly independent of other layers. A wide range of medical image preprocessing, registration, and segmentation methods are implemented using open source libraries. Desktop-like user interaction is provided by using AJAX technology in the web-user-interface. For the visualization functionality of the software, the VRML standard is used to provide 3D features over the web. Integration of these technologies has allowed implementation of our purely web-based software with high functionality without requiring powerful computational resources in the client side. The user-interface is designed such that the users can select appropriate parameters for practical research and clinical studies. PMID:20022133

  13. 2-D traveltime and waveform inversion for improved seismic imaging: Naga Thrust and Fold Belt, India

    NASA Astrophysics Data System (ADS)

    Jaiswal, Priyank; Zelt, Colin A.; Bally, Albert W.; Dasgupta, Rahul

    2008-05-01

    Exploration along the Naga Thrust and Fold Belt in the Assam province of Northeast India encounters geological as well as logistic challenges. Drilling for hydrocarbons, traditionally guided by surface manifestations of the Naga thrust fault, faces additional challenges in the northeast where the thrust fault gradually deepens leaving subtle surface expressions. In such an area, multichannel 2-D seismic data were collected along a line perpendicular to the trend of the thrust belt. The data have a moderate signal-to-noise ratio and suffer from ground roll and other acquisition-related noise. In addition to data quality, the complex geology of the thrust belt limits the ability of conventional seismic processing to yield a reliable velocity model which in turn leads to poor subsurface image. In this paper, we demonstrate the application of traveltime and waveform inversion as supplements to conventional seismic imaging and interpretation processes. Both traveltime and waveform inversion utilize the first arrivals that are typically discarded during conventional seismic processing. As a first step, a smooth velocity model with long wavelength characteristics of the subsurface is estimated through inversion of the first-arrival traveltimes. This velocity model is then used to obtain a Kirchhoff pre-stack depth-migrated image which in turn is used for the interpretation of the fault. Waveform inversion is applied to the central part of the seismic line to a depth of ~1 km where the quality of the migrated image is poor. Waveform inversion is performed in the frequency domain over a series of iterations, proceeding from low to high frequency (11-19 Hz) using the velocity model from traveltime inversion as the starting model. In the end, the pre-stack depth-migrated image and the waveform inversion model are jointly interpreted. This study demonstrates that a combination of traveltime and waveform inversion with Kirchhoff pre-stack depth migration is a promising approach for the interpretation of geological structures in a thrust belt.

  14. High-resolution GPR imaging using a nonstandard 2D EEMD technique

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Sung; Jeng*, Yih; Yu, Hung-Ming

    2013-04-01

    Ground Penetrating Radar (GPR) data are affected by a variety of factors. Linear and nonlinear data processing methods each have been widely applied to the GPR use in geophysical and engineering investigations. For complicated data such as the shallow earth image of urban area, a better result can be achieved by integrating both approaches. In this study, we introduce a nonstandard 2D EEMD approach, which integrates the natural logarithm transformed (NLT) ensemble empirical mode decomposition (EEMD) method with the linear filtering technique to process GPR images. The NLT converts the data into logarithmic values; therefore, it permits a wide dynamic range for the recorded GPR data to be presented. The EEMD dyadic filter bank decomposes the data into multiple components ready for image reconstruction. Consequently, the NLT EEMD method provides a new way of nonlinear energy compensating and noise filtering with results having minimal artifacts. However, horizontal noise in the GPR time-distance section may be enhanced after NLT process in some cases. To solve the dilemma, we process the data two dimensionally. At first, the vertical background noise of each GPR trace is removed by using a standard linear method, the background noise removal algorithm, or simply by performing the sliding background removal filter. After that, the NLT is applied to the data for examining the horizontal coherent energy. Next, we employ the EEMD filter bank horizontally at each time step to remove the horizontal coherent energy. After removing the vertical background noise and horizontal coherent energy, a vertical EEMD method is then applied to generate a filter bank of the GPR time-distance section for final image reconstruction. Two buried models imitating common shallow earth targets are used to verify the effectiveness of the proposed scheme. One model is a brick cistern buried in a disturbed site of poor reflection quality. The other model is a buried two-stack metallic target that the signal reflected from the lower stack is often masked by the upper one. Compared with the results obtained by using standard processing methods, the proposed approach significantly improves the target resolution. A field example is also provided to demonstrate the competence of the proposed scheme. Keywords: GPR; 2D EEMD; Logarithmic transform; Horizontal coherent energy

  15. A new method of diaphragm apex motion detection from 2D projection images of mega-voltage cone beam CT.

    PubMed

    Chen, Mingqing; Bai, Junjie; Siochi, R Alfredo C

    2013-02-01

    To present a new method of estimating 3D positions of the ipsi-lateral hemi-diaphragm apex (IHDA) from 2D projection images of mega-voltage cone beam CT (MVCBCT). The detection framework reconstructs a 3D volume from all the 2D projection images. An initial estimated 3D IHDA position is determined in this volume based on an imaging processing pipeline, including Otsu thresholding, connected component labeling and template matching. This initial position is then projected onto each 2D projection image to create a region of interest (ROI). To accurately detect the IHDA position in 2D projection space, two methods, dynamic Hough transform (DHT) and a tracking approach based on a joint probability density function (PDF) are developed. Both methods utilize a double-parabola model to fit the 2D diaphragm boundary. The 3D IHDA motion in the superior-inferior (SI) direction is estimated from the initial static 3D position and the detected 2D positions in projection space. The two Hough-based detection methods are tested on 35 MVCBCT scans from 15 patients. The detection is compared to manually identified IHDA positions in 2D projection space by three clinicians. An average and standard deviation of 4.252 ± 3.354 and 2.485 ± 1.750 mm was achieved for DHT and tracking-based approaches respectively, compared with the inter-expert variance among three experts of 1.822 ± 1.106 mm. Based on the results of the scans, the PDF tracking-based approach appears more robust than the DHT. The combination of the automatic ROI localization and the tracking-based approach is a quicker and more accurate method of extracting 3D IHDA motion from 2D projection images. PMID:23321998

  16. A new method of diaphragm apex motion detection from 2D projection images of mega-voltage cone beam CT

    NASA Astrophysics Data System (ADS)

    Chen, Mingqing; Bai, Junjie; Siochi, R. Alfredo C.

    2013-02-01

    To present a new method of estimating 3D positions of the ipsi-lateral hemi-diaphragm apex (IHDA) from 2D projection images of mega-voltage cone beam CT (MVCBCT). The detection framework reconstructs a 3D volume from all the 2D projection images. An initial estimated 3D IHDA position is determined in this volume based on an imaging processing pipeline, including Otsu thresholding, connected component labeling and template matching. This initial position is then projected onto each 2D projection image to create a region of interest (ROI). To accurately detect the IHDA position in 2D projection space, two methods, dynamic Hough transform (DHT) and a tracking approach based on a joint probability density function (PDF) are developed. Both methods utilize a double-parabola model to fit the 2D diaphragm boundary. The 3D IHDA motion in the superior-inferior (SI) direction is estimated from the initial static 3D position and the detected 2D positions in projection space. The two Hough-based detection methods are tested on 35 MVCBCT scans from 15 patients. The detection is compared to manually identified IHDA positions in 2D projection space by three clinicians. An average and standard deviation of 4.252 ± 3.354 and 2.485 ± 1.750 mm was achieved for DHT and tracking-based approaches respectively, compared with the inter-expert variance among three experts of 1.822 ± 1.106 mm. Based on the results of the scans, the PDF tracking-based approach appears more robust than the DHT. The combination of the automatic ROI localization and the tracking-based approach is a quicker and more accurate method of extracting 3D IHDA motion from 2D projection images.

  17. On the assimilation of flood extension images into 2D shallow-water models

    NASA Astrophysics Data System (ADS)

    Monnier, J.; Couderc, F.; Dartus, D.; Madec, R.; Vila, J.

    2012-12-01

    In river hydraulics, assimilation of water level measurements at gauging stations is well controlled, while assimilation of images (e.g. from satellite) is still delicate. In the present talk, we address the richness of satellite information to constraint a 2D shallow-water model, and present also related difficulties. A preliminary study done on Mosel river is presented in [LaMo] [HoLaMoPu]. On selected parts of the image, an 0th order model flow allows to obtain some reliable water levels with quantified uncertainties (C. Puech et al.). Next, variationnal sensitivities (based on a gradient computation and adjoint equations) reveal some difficulties that a model designer have to tackle (e.g. roughness parameters at open boundaries), and allow to better understand both the model and the flow. Next, a variational data assimilation algorithm (4D-var) shows that such data lead to a better calibration of the model (e.g. roughness coefficients) and potentially allows to identify the incoming and/or outgoing flow at open boundaries, [LaMo] [HoLaMoPu]. On the other side, the flood dynamic extension is difficult to represent accurately using a 2D SW model since the wet-dry front dynamics is difficult to compute. We compare some 2nd order finite volume solvers and obtain an accurate and stable scheme at wet-dry front. Then, we present some basic rules of compatibility between data and mesh resolution in order to be reliable enough to constraint the model with flood extension data, [CoMaMoViDa]. All the algorithms are implemented into DassFlow software (Fortran, MPI, adjoint) [Da]. [CoMaMoViDa] F. Couderc, R. Madec, J. Monnier, J.-P. Vila, D. Dartus. "Sensitivity analysis and variational data assimilation for geophysical shallow water flows". Submitted. [Da] DassFlow - Data Assimilation for Free Surface Flows. Open-source computational software http://www-gmm.insa-toulouse.fr/~monnier/DassFlow/ [HoLaMoPu] R. Hostache, X. Lai, J. Monnier, C. Puech. "Assimilation of spatial distributed water levels into a shallow-water flood model. Part II: using a remote sensing image of Mosel river". J. Hydrology (2010). [LaMo] X. Lai, J. Monnier. "Assimilation of spatial distributed water levels into a shallow-water flood model. Part I: mathematical method and test case". J. Hydrology (2009). [RoDa] Roux H., Dartus D. « Use of Parameter Optimization to Estimate a Flood Wave: Potential Applications to Remote Sensing of Rivers ». J. Hydrology (2006).

  18. Ultrasound 2D strain estimator based on image registration for ultrasound elastography

    NASA Astrophysics Data System (ADS)

    Yang, Xiaofeng; Torres, Mylin; Kirkpatrick, Stephanie; Curran, Walter J.; Liu, Tian

    2014-03-01

    In this paper, we present a new approach to calculate 2D strain through the registration of the pre- and post-compression (deformation) B-mode image sequences based on an intensity-based non-rigid registration algorithm (INRA). Compared with the most commonly used cross-correlation (CC) method, our approach is not constrained to any particular set of directions, and can overcome displacement estimation errors introduced by incoherent motion and variations in the signal under high compression. This INRA method was tested using phantom and in vivo data. The robustness of our approach was demonstrated in the axial direction as well as the lateral direction where the standard CC method frequently fails. In addition, our approach copes well under large compression (over 6%). In the phantom study, we computed the strain image under various compressions and calculated the signal-to-noise (SNR) and contrast-to-noise (CNS) ratios. The SNR and CNS values of the INRA method were much higher than those calculated from the CC-based method. Furthermore, the clinical feasibility of our approach was demonstrated with the in vivo data from patients with arm lymphedema.

  19. Coronary arteries motion modeling on 2D x-ray images

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Sundar, Hari

    2012-02-01

    During interventional procedures, 3D imaging modalities like CT and MRI are not commonly used due to interference with the surgery and radiation exposure concerns. Therefore, real-time information is usually limited and building models of cardiac motion are difficult. In such case, vessel motion modeling based on 2-D angiography images become indispensable. Due to issues with existing vessel segmentation algorithms and the lack of contrast in occluded vessels, manual segmentation of certain branches is usually necessary. In addition, such occluded branches are the most important vessels during coronary interventions and obtaining motion models for these can greatly help in reducing the procedure time and radiation exposure. Segmenting different cardiac phases independently does not guarantee temporal consistency and is not efficient for occluded branches required manual segmentation. In this paper, we propose a coronary motion modeling system which extracts the coronary tree for every cardiac phase, maintaining the segmentation by tracking the coronary tree during the cardiac cycle. It is able to map every frame to the specific cardiac phase, thereby inferring the shape information of the coronary arteries using the model corresponding to its phase. Our experiments show that our motion modeling system can achieve promising results with real-time performance.

  20. FluoRender: An Application of 2D Image Space Methods for 3D and 4D Confocal Microscopy Data Visualization in Neurobiology Research

    PubMed Central

    Wan, Yong; Otsuna, Hideo; Chien, Chi-Bin; Hansen, Charles

    2013-01-01

    2D image space methods are processing methods applied after the volumetric data are projected and rendered into the 2D image space, such as 2D filtering, tone mapping and compositing. In the application domain of volume visualization, most 2D image space methods can be carried out more efficiently than their 3D counterparts. Most importantly, 2D image space methods can be used to enhance volume visualization quality when applied together with volume rendering methods. In this paper, we present and discuss the applications of a series of 2D image space methods as enhancements to confocal microscopy visualizations, including 2D tone mapping, 2D compositing, and 2D color mapping. These methods are easily integrated with our existing confocal visualization tool, FluoRender, and the outcome is a full-featured visualization system that meets neurobiologists’ demands for qualitative analysis of confocal microscopy data. PMID:23584131

  1. Crystallographic Image Processing with Unambiguous 2D Bravais Lattice Identification on the Basis of a Geometric Akaike Information Criterion

    NASA Astrophysics Data System (ADS)

    Bilyeu, Taylor Thomas

    Crystallographic image processing (CIP) is a technique first used to aid in the structure determination of periodic organic complexes imaged with a high-resolution transmission electron microscope (TEM). The technique has subsequently been utilized for TEM images of inorganic crystals, scanning TEM images, and even scanning probe microscope (SPM) images of two-dimensional periodic arrays. We have written software specialized for use on such SPM images. A key step in the CIP process requires that an experimental image be classified as one of only 17 possible mathematical plane symmetry groups. The current methods used for making this symmetry determination are not entirely objective, and there is no generally accepted method for measuring or quantifying deviations from ideal symmetry. Here, we discuss the crystallographic symmetries present in real images and the general techniques of CIP, with emphasis on the current methods for symmetry determination in an experimental 2D periodic image. The geometric Akaike information criterion (AIC) is introduced as a viable statistical criterion for both quantifying deviations from ideal symmetry and determining which 2D Bravais lattice best fits the experimental data from an image being processed with CIP. By objectively determining the statistically favored 2D Bravais lattice, the determination of plane symmetry in the CIP procedure can be greatly improved. As examples, we examine scanning tunneling microscope images of 2D molecular arrays of the following compounds: cobalt phthalocyanine on Au (111) substrate; nominal cobalt phthalocyanine on Ag (111); tetraphenoxyphthalocyanine on highly oriented pyrolitic graphite; hexaazatriphenylene-hexacarbonitrile on Ag (111). We show that the geometric AIC procedure can unambiguously determine which 2D Bravais lattice fits the experimental data for a variety of different lattice types. In some cases, the geometric AIC procedure can be used to determine which plane symmetry group best fits the experimental data, when traditional CIP methods fail to do so.

  2. 2-D arterial wall motion imaging using ultrafast ultrasound and transverse oscillations.

    PubMed

    Salles, Sebastien; Chee, Adrian J Y; Garcia, Damien; Yu, Alfred C H; Vray, Didier; Liebgott, Herve

    2015-06-01

    Ultrafast ultrasound is a promising imaging modality that enabled, inter alia, the development of pulse wave imaging and the local velocity estimation of the so-called pulse wave for a quantitative evaluation of arterial stiffness. However, this technique only focuses on the propagation of the axial displacement of the artery wall, and most techniques are not specific to the intima-media complex and do not take into account the longitudinal motion of this complex. Within this perspective, this paper presents a study of two-dimensional tissue motion estimation in ultrafast imaging combining transverse oscillations, which can improve motion estimation in the transverse direction, i.e., perpendicular to the beam axis, and a phase-based motion estimation. First, the method was validated in simulation. Two-dimensional motion, inspired from a real data set acquired on a human carotid artery, was applied to a numerical phantom to produce a simulation data set. The estimated motion showed axial and lateral mean errors of 4.2 ± 3.4 μm and 9.9 ± 7.9 μm, respectively. Afterward, experimental results were obtained on three artery phantoms with different wall stiffnesses. In this study, the vessel phantoms did not contain a pure longitudinal displacement. The longitudinal displacements were induced by the axial force produced by the wall's axial dilatation. This paper shows that the approach presented is able to perform 2-D tissue motion estimation very accurately even if the displacement values are very small and even in the lateral direction, making it possible to estimate the pulse wave velocity in both the axial and longitudinal directions. This demonstrates the method's potential to estimate the velocity of purely longitudinal waves propagating in the longitudinal direction. Finally, the stiffnesses of the three vessel phantom walls investigated were estimated with an average relative error of 2.2%. PMID:26067039

  3. Measuring significant inhomogeneity and anisotropy in indoor convective air turbulence in the presence of 2D temperature gradient

    NASA Astrophysics Data System (ADS)

    Mohammady Razi, E.; Rasouli, Saifollah

    2014-04-01

    Using a novel set up, experimental study of the statistical properties of a light beam propagating horizontally through indoor convective air turbulence in the presence of a 2D temperature gradient (TG) is presented. A laser beam enters a telescope from its back focal point by virtue of an optical fiber and is expanded and recollimated by it and then passes through the turbulent area. Then the beam enters another telescope’s aperture. A mask consisting of four similar widely separated small subapertures was installed in front of the second telescope’s aperture. The subapertures were equidistant from the optical axis of the telescope and located at the corners of a square. A flat plane heater is used to produce a vertical TG in the medium. Due to the limited width of the heater, a horizontal component for the TG appeared. Near the focal plane of the second telescope, four distinct images of the source are formed and recorded by a CCD camera. Due to the turbulence all the images (spots) in the successive frames fluctuate. Using the four spot displacements we have calculated the fluctuations of the angle of arrival (AA) over the subapertures. The statistical properties of the optical turbulence are investigated using variance analysis of the AA component fluctuations at horizontal and vertical directions over the subapertures for different temperatures of the heater at different heights of the beam path from the heater. Experimental results show that when the heater is turned off, the variances of horizontal and vertical components of the AA fluctuations are approximately equal to zero over all the subapertures. When it is turned on, the variance of the horizontal component of the AA fluctuations over all of the subapertures are larger than those from the vertical one. In addition, in this case, we find a significant dependence of the variance of the AA components on the height from the heater.

  4. Self-calibration of cone-beam CT geometry using 3D-2D image registration

    NASA Astrophysics Data System (ADS)

    Ouadah, S.; Stayman, J. W.; Gang, G. J.; Ehtiati, T.; Siewerdsen, J. H.

    2016-04-01

    Robotic C-arms are capable of complex orbits that can increase field of view, reduce artifacts, improve image quality, and/or reduce dose; however, it can be challenging to obtain accurate, reproducible geometric calibration required for image reconstruction for such complex orbits. This work presents a method for geometric calibration for an arbitrary source-detector orbit by registering 2D projection data to a previously acquired 3D image. It also yields a method by which calibration of simple circular orbits can be improved. The registration uses a normalized gradient information similarity metric and the covariance matrix adaptation-evolution strategy optimizer for robustness against local minima and changes in image content. The resulting transformation provides a ‘self-calibration’ of system geometry. The algorithm was tested in phantom studies using both a cone-beam CT (CBCT) test-bench and a robotic C-arm (Artis Zeego, Siemens Healthcare) for circular and non-circular orbits. Self-calibration performance was evaluated in terms of the full-width at half-maximum (FWHM) of the point spread function in CBCT reconstructions, the reprojection error (RPE) of steel ball bearings placed on each phantom, and the overall quality and presence of artifacts in CBCT images. In all cases, self-calibration improved the FWHM—e.g. on the CBCT bench, FWHM  =  0.86 mm for conventional calibration compared to 0.65 mm for self-calibration (p  <  0.001). Similar improvements were measured in RPE—e.g. on the robotic C-arm, RPE  =  0.73 mm for conventional calibration compared to 0.55 mm for self-calibration (p  <  0.001). Visible improvement was evident in CBCT reconstructions using self-calibration, particularly about high-contrast, high-frequency objects (e.g. temporal bone air cells and a surgical needle). The results indicate that self-calibration can improve even upon systems with presumably accurate geometric calibration and is applicable to situations where conventional calibration is not feasible, such as complex non-circular CBCT orbits and systems with irreproducible source-detector trajectory.

  5. Self-calibration of cone-beam CT geometry using 3D-2D image registration.

    PubMed

    Ouadah, S; Stayman, J W; Gang, G J; Ehtiati, T; Siewerdsen, J H

    2016-04-01

    Robotic C-arms are capable of complex orbits that can increase field of view, reduce artifacts, improve image quality, and/or reduce dose; however, it can be challenging to obtain accurate, reproducible geometric calibration required for image reconstruction for such complex orbits. This work presents a method for geometric calibration for an arbitrary source-detector orbit by registering 2D projection data to a previously acquired 3D image. It also yields a method by which calibration of simple circular orbits can be improved. The registration uses a normalized gradient information similarity metric and the covariance matrix adaptation-evolution strategy optimizer for robustness against local minima and changes in image content. The resulting transformation provides a 'self-calibration' of system geometry. The algorithm was tested in phantom studies using both a cone-beam CT (CBCT) test-bench and a robotic C-arm (Artis Zeego, Siemens Healthcare) for circular and non-circular orbits. Self-calibration performance was evaluated in terms of the full-width at half-maximum (FWHM) of the point spread function in CBCT reconstructions, the reprojection error (RPE) of steel ball bearings placed on each phantom, and the overall quality and presence of artifacts in CBCT images. In all cases, self-calibration improved the FWHM-e.g. on the CBCT bench, FWHM  =  0.86 mm for conventional calibration compared to 0.65 mm for self-calibration (p  <  0.001). Similar improvements were measured in RPE-e.g. on the robotic C-arm, RPE  =  0.73 mm for conventional calibration compared to 0.55 mm for self-calibration (p  <  0.001). Visible improvement was evident in CBCT reconstructions using self-calibration, particularly about high-contrast, high-frequency objects (e.g. temporal bone air cells and a surgical needle). The results indicate that self-calibration can improve even upon systems with presumably accurate geometric calibration and is applicable to situations where conventional calibration is not feasible, such as complex non-circular CBCT orbits and systems with irreproducible source-detector trajectory. PMID:26961687

  6. Image Outlier Detection and Feature Extraction via L1-Norm-Based 2D Probabilistic PCA.

    PubMed

    Ju, Fujiao; Sun, Yanfeng; Gao, Junbin; Hu, Yongli; Yin, Baocai

    2015-12-01

    This paper introduces an L1-norm-based probabilistic principal component analysis model on 2D data (L1-2DPPCA) based on the assumption of the Laplacian noise model. The Laplacian or L1 density function can be expressed as a superposition of an infinite number of Gaussian distributions. Under this expression, a Bayesian inference can be established based on the variational expectation maximization approach. All the key parameters in the probabilistic model can be learned by the proposed variational algorithm. It has experimentally been demonstrated that the newly introduced hidden variables in the superposition can serve as an effective indicator for data outliers. Experiments on some publicly available databases show that the performance of L1-2DPPCA has largely been improved after identifying and removing sample outliers, resulting in more accurate image reconstruction than the existing PCA-based methods. The performance of feature extraction of the proposed method generally outperforms other existing algorithms in terms of reconstruction errors and classification accuracy. PMID:26292341

  7. Parametric phase information based 2D Cepstrum PSF estimation method for blind de-convolution of ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Kang, Jooyoung; Park, Sung-Chan; Kim, Jung-ho; Song, Jongkeun

    2014-02-01

    In the ultrasound imaging system, blurring which occurs after passing through ultrasound scanner system, represents point spread function (PSF) that describes the response of the ultrasound imaging system to a point source distribution. So, de-blurring can be achieved by de-convolving the ultrasound images with an estimated of corresponding PSF. However, it is hard to attain an accurate estimation of PSF due to the unknown properties of the tissues of the human body through the ultrasound signal propagates. In this paper, we present a new method for PSF estimation in the Fourier domain (FD) based on parametric minimum phase information, and simultaneously, it performs fast 2D de-convolution in the ultrasound imaging system. Although most of complex cepstrum methods [14], are obtained using complex 2D phase unwrapping [18] [19] in order to estimate the FD-phase information of PSF, our algorithm estimates the 2D PSF using 2D FD-phase information with the parametric weighting factor α and β. They affect the feature of PSF shapes.This makes the computations much simpler and the estimation more accurate. Our algorithm works on the beam-formed uncompressed radio-frequency data, with pre-measured and estimated 2D PSFs database from actual probe used. We have tested our algorithm with vera-sonic system and commercial ultrasound scanner (Philips C4-2), in known speed of sound phantoms and unknown speeds in vivo scans.

  8. Evaluation of storage phosphor imaging for quantitative analysis of 2-D gels using the Quest II system.

    PubMed

    Patterson, S D; Latter, G I

    1993-12-01

    The advent of storage phosphor technology has been of considerable benefit to the imaging of gel-separated radiolabeled proteins due to the rapid and quantitative nature of the data acquisition process. Previously, times over one month were required to obtain fluorographs of the same gel to yield data of sufficient dynamic range for quantitative analysis of high-resolution two-dimensional (2-D) gels. As we are in the process of building a human 2-D gel protein database, and therefore have a high throughput of 2-D gels both to image and quantitate using the Quest II software, we undertook an evaluation of a storage phosphor imager, including an evaluation of signal fade. The results of this evaluation demonstrate the feasibility of using such a system, and we describe the procedures that allow us to use this technique for quantitative analysis of many complex 2-D gel patterns. These procedures include a useful batch printing program that allows printing of many images in a non-interactive mode. Examples will be presented of how autoradiography, using storage phosphor plates and the Quest II system, have enabled us to begin building a human 2-D gel protein database including posttranslational modification information, without the previous time constraints associated with such a project. PMID:8292341

  9. Substorm development as observed by Interball UV imager and 2-D magnetic array

    NASA Astrophysics Data System (ADS)

    Lyatsky, W.; Cogger, L. L.; Jackel, B.; Hamza, A. M.; Hughes, W. J.; Murr, D.; Rasmussen, O.

    2001-10-01

    Results of the study of two substorms from Interball auroral UV measurements and two-dimensional patterns of equivalent ionospheric currents derived from the MACCS/CANOPUS and Greenland magnetometer arrays are presented. Substorm development in 2-D equivalent ionospheric current patterns may be described in terms of the formation of two vortices in the equivalent currents: a morning vortex related to downward field-aligned current and an evening vortex related to upward field-aligned current. Poleward propagation of the magnetic disturbances during substorm expansive phase was found to be associated mainly with a poleward displacement of the morning vortex, whereas the evening vortex remained approximately at the same position. As a result, the initial quasi-azimuthal separation of the vortices was replaced by their quasi-meridional separation at substorm maximum. Interball UV images during this period showed the formation of a bright auroral border at the poleward edge of substorm auroral bulge. The auroral UV images showed also that the auroral distribution in the region between the polar border and the main auroral oval tends to have a form of bubbles or petals growing from a bright protuberant region on the equatorward boundary of the auroral oval. However, the resolution of the UV imager was not sufficient for the reliable separation of such the structures, therefore, this result should be considered as preliminary. Overlapping of the auroral UV images onto equivalent current patterns shows that the bright substorm surge was well collocated with the evening vortex whereas the poleward auroral border did not coincide with any evident feature in equivalent ionospheric currents and was located several degrees equatorward of the morning current vortex center related to downward field-aligned current. The ground-based magnetic array allowing us to obtain instantaneous patterns of equivalent ionospheric currents gives a possibility to propose a new index for substorm activity such as the magnitude of the total current between the centers of the morning and evening vortices. Such integral index would not depend on where the substorm is located and be unaffected by the migration of substorm activity poleward or equatorward.

  10. Room-Temperature Optical Tunability and Inhomogeneous Broadening in 2D-Layered Organic-Inorganic Perovskite Pseudobinary Alloys.

    PubMed

    Lanty, Gaëtan; Jemli, Khaoula; Wei, Yi; Leymarie, Joël; Even, Jacky; Lauret, Jean-Sébastien; Deleporte, Emmanuelle

    2014-11-20

    We focus here our attention on a particular family of 2D-layered and 3D hybrid perovskite molecular crystals, the mixed perovskites (C6H5-C2H4-NH3)2PbZ4(1-x)Y4x and (CH3-NH3)PbZ3(1-x)Y3x, where Z and Y are halogen ions such as I, Br, and Cl. Studying experimentally the disorder-induced effects on the optical properties of the 2D mixed layered materials, we demonstrate that they can be considered as pseudobinary alloys, exactly like Ga1-xAlxAs, Cd1-xHgxTe inorganic semiconductors, or previously reported 3D mixed hybrid perovskite compounds. 2D-layered and 3D hybrid perovskites afford similar continuous optical tunability at room temperature. Our theoretical analysis allows one to describe the influence of alloying on the excitonic properties of 2D-layered perovskite molecular crystals. This model is further refined by considering different Bohr radii for pure compounds. This study confirms that despite a large binding energy of several 100 meV, the 2D excitons present a Wannier character rather than a Frenkel character. The small inhomogeneous broadening previously reported in 3D hybrid compounds at low temperature is similarly consistent with the Wannier character of free excitons. PMID:26276477

  11. An influence of solar activity on latitudinal distribution of atmospheric ozone and temperature in 2-D radiative-photochemical model

    NASA Technical Reports Server (NTRS)

    Dyominov, I. G.

    1989-01-01

    On the basis of the 2-D radiative-photochemical model of the ozone layer at heights 0 to 60 km in the Northern Hemisphere there are revealed and analyzed in detail the characteristic features of the season-altitude-latitude variations of ozone and temperature due to changes of the solar flux during the 11 year cycle, electron and proton precipitations.

  12. Application of 2D and 3D Digital Image Correlation on CO2-like altered carbonate

    NASA Astrophysics Data System (ADS)

    zinsmeister, Louis; Dautriat, Jérémie; Dimanov, Alexandre; Raphanel, Jean; Bornert, Michel

    2013-04-01

    In order to provide mechanical constitutive laws for reservoir monitoring during CO2 long term storage, we studied the mechanical properties of Lavoux limestone before and after a homogeneous alteration following the protocol of acid treatments defined by Egermann et al, (2006). The mechanical data have been analysed at the light of systematic microstructural investigations. Firstly, the alteration impact on the evolution of flow properties related to microstructural changes was studied at successive levels of alteration by classical petrophysical measurements of porosity and permeability (including NMR, mercury porosimetry and laser diffraction) and by observations of microstructures on thin sections and by SEM. Secondly, the mechanical properties of the samples were investigated by classical (macroscopic) triaxial and uniaxial tests and are discussed in terms of the structural modifications. The macroscopic tests indicate that the alteration weakens the material, according to the observed decrease of elastic moduli and Uniaxial Compressive Strengths, from 29MPa to 19MPa after 6 cycles of acid treatments. The study is further complemented by 2D full (mechanical) field measurements, thanks to Digital Image Correlation (DIC) performed on images acquired during the uniaxial tests. This technique allows for continuous quantitative micro-mechanical monitoring in terms of deformation history and localisation processes during compression. This technique was applied on both intact and altered materials and at different scales of observation: (i) cm-sized samples were compressed in a classical load frame and optically imaged, (ii) mm-sized samples were loaded with a miniaturized compression rig implemented within a Scanning Electron Microscope. At last, 3D full field measurements were performed by 3D-DIC on mm-sized samples, which were compressed "in-situ" an X-ray microtomograph thanks to a miniaturized triaxial cell allowing for confining pressures of up to 15 MPa. At the macroscale and for the intact samples, a diffuse accommodation of the deformation is observed during the pseudo elastic regime, followed by sudden failure propagation after the peak stress. Conversely, the altered samples exhibit much more localized and pronounced deformation levels. At the SEM scale for the intact samples, but closure of the porosity, failure precursors and localized deformation were not observed. In opposition, the altered samples showed early opening of microcracks at the grain junctions. Finally, at the µ-tomograph resolution (5µm/voxel) and in triaxial conditions, we observed for intact samples at macro and micro scales similar behaviour as for optical and SEM characterization. At 5 MPa of confining pressure the altered samples avoid brittle failure and a few shear bands are visible. As previously inferred from 2D-DIC, we observed strong and early localization of deformation, but the limited resolution of the µ-tomograph did not allow to clearly evidence microcracks. The DIC results suggest that besides the overall increase of porosity, the dissolution processes enhance the local heterogeneities of the porous network, which phenomenon further increases the weakening of the materials.

  13. Application of conformal map theory for design of 2-D ultrasonic array structure for NDT imaging application: a feasibility study.

    PubMed

    Ramadas, Sivaram N; Jackson, Joseph C; Dziewierz, Jerzy; O'Leary, Richard; Gachagan, Anthony

    2014-03-01

    Two-dimensional ultrasonic phased arrays are becoming increasingly popular in nondestructive evaluation (NDE). Sparse array element configurations are required to fully exploit the potential benefits of 2-D phased arrays. This paper applies the conformal mapping technique as a means of designing sparse 2-D array layouts for NDE applications. Modeling using both Huygens' field prediction theory and 2-D fast Fourier transformation is employed to study the resulting new structure. A conformal power map was used that, for fixed beam width, was shown in simulations to have a greater contrast than rectangular or random arrays. A prototype aperiodic 2-D array configuration for direct contact operation in steel, with operational frequency ~3 MHz, was designed using the array design principle described in this paper. Experimental results demonstrate a working sparse-array transducer capable of performing volumetric imaging. PMID:24569253

  14. Quantitative-phase-contrast imaging of a two-level surface described as a 2D linear filtering process.

    PubMed

    Lovicar, Luděk; Komrska, Jiří; Chmelík, Radim

    2010-09-27

    The paper deals with quantitative phase imaging of two-height-level surface reliefs. The imaging is considered to be a linear system and, consequently, the Fourier transform of the image is the product of the Fourier transform of a 2D function characterizing the surface and a specific 2D coherent transfer function. The Fourier transform of functions specifying periodic surface reliefs is factorized into two functions similar to lattice and structure amplitudes in crystal structure analysis. The approach to the imaging process described in the paper enables us to examine the dependence of the phase image on the surface geometry. Theoretical results are verified experimentally by means of a digital holographic microscope. PMID:20940953

  15. Register cardiac fiber orientations from 3D DTI volume to 2D ultrasound image of rat hearts

    NASA Astrophysics Data System (ADS)

    Qin, Xulei; Wang, Silun; Shen, Ming; Zhang, Xiaodong; Lerakis, Stamatios; Wagner, Mary B.; Fei, Baowei

    2015-03-01

    Two-dimensional (2D) ultrasound or echocardiography is one of the most widely used examinations for the diagnosis of cardiac diseases. However, it only supplies the geometric and structural information of the myocardium. In order to supply more detailed microstructure information of the myocardium, this paper proposes a registration method to map cardiac fiber orientations from three-dimensional (3D) magnetic resonance diffusion tensor imaging (MR-DTI) volume to the 2D ultrasound image. It utilizes a 2D/3D intensity based registration procedure including rigid, log-demons, and affine transformations to search the best similar slice from the template volume. After registration, the cardiac fiber orientations are mapped to the 2D ultrasound image via fiber relocations and reorientations. This method was validated by six images of rat hearts ex vivo. The evaluation results indicated that the final Dice similarity coefficient (DSC) achieved more than 90% after geometric registrations; and the inclination angle errors (IAE) between the mapped fiber orientations and the gold standards were less than 15 degree. This method may provide a practical tool for cardiologists to examine cardiac fiber orientations on ultrasound images and have the potential to supply additional information for diagnosis of cardiac diseases.

  16. Measurements of Thermal Conductivity of Superfluid Helium Near its Transition Temperature T(sub lambda) in a 2D Confinement

    NASA Technical Reports Server (NTRS)

    Jerebets, Sergei

    2004-01-01

    We report our recent experiments on thermal conductivity measurements of superfluid He-4 near its phase transition in a two-dimensional (2D) confinement under saturated vapor pressure. A 2D confinement is created by 2-mm- and 1-mm-thick glass capillary plates, consisting of densely populated parallel microchannels with cross-sections of 5 x 50 and 1 x 10 microns, correspondingly. A heat current (2 < Q < 400 nW/sq cm) was applied along the channels long direction. High-resolution measurements were provided by DC SQUID-based high-resolution paramagnetic salt thermometers (HRTs) with a nanokelvin resolution. We might find that thermal conductivity of confined helium is finite at the bulk superfluid transition temperature. Our 2D results will be compared with those in a bulk and 1D confinement.

  17. Process to generate a synthetic diagnostic for microwave imaging reflectometry with the full-wave code FWR2D.

    PubMed

    Ren, X; Domier, C W; Kramer, G; Luhmann, N C; Muscatello, C M; Shi, L; Tobias, B J; Valeo, E

    2014-11-01

    A synthetic microwave imaging reflectometer (MIR) diagnostic employing the full-wave reflectometer code (FWR2D) has been developed and is currently being used to guide the design of real systems, such as the one recently installed on DIII-D. The FWR2D code utilizes real plasma profiles as input, and it is combined with optical simulation tools for synthetic diagnostic signal generation. A detailed discussion of FWR2D and the process to generate the synthetic signal are presented in this paper. The synthetic signal is also compared to a prescribed density fluctuation spectrum to quantify the imaging quality. An example is presented with H-mode-like plasma profiles derived from a DIII-D discharge, where the MIR focal is located in the pedestal region. It is shown that MIR is suitable for diagnosing fluctuations with poloidal wavenumber up to 2.0 cm(-1) and fluctuation amplitudes less than 5%. PMID:25430276

  18. Sparse matrix beamforming and image reconstruction for real-time 2D HIFU monitoring using Harmonic Motion Imaging for Focused Ultrasound (HMIFU) with in vitro validation

    PubMed Central

    Hou, Gary Y.; Provost, Jean; Grondin, Julien; Wang, Shutao; Marquet, Fabrice; Bunting, Ethan; Konofagou, Elisa E.

    2015-01-01

    Harmonic Motion Imaging for Focused Ultrasound (HMIFU) is a recently developed High-Intensity Focused Ultrasound (HIFU) treatment monitoring method. HMIFU utilizes an Amplitude-Modulated (fAM = 25 Hz) HIFU beam to induce a localized focal oscillatory motion, which is simultaneously estimated and imaged by confocally-aligned imaging transducer. HMIFU feasibilities have been previously shown in silico, in vitro, and in vivo in 1-D or 2-D monitoring of HIFU treatment. The objective of this study is to develop and show the feasibility of a novel fast beamforming algorithm for image reconstruction using GPU-based sparse-matrix operation with real-time feedback. In this study, the algorithm was implemented onto a fully integrated, clinically relevant HMIFU system composed of a 93-element HIFU transducer (fcenter = 4.5MHz) and coaxially-aligned 64-element phased array (fcenter = 2.5MHz) for displacement excitation and motion estimation, respectively. A single transmit beam with divergent beam transmit was used while fast beamforming was implemented using a GPU-based delay-and-sum method and a sparse-matrix operation. Axial HMI displacements were then estimated from the RF signals using a 1-D normalized cross-correlation method and streamed to a graphic user interface. The present work developed and implemented a sparse matrix beamforming onto a fully-integrated, clinically relevant system, which can stream displacement images up to 15 Hz using a GPU-based processing, an increase of 100 fold in rate of streaming displacement images compared to conventional CPU-based conventional beamforming and reconstruction processing. The achieved feedback rate is also currently the fastest and only approach that does not require interrupting the HIFU treatment amongst the acoustic radiation force based HIFU imaging techniques. Results in phantom experiments showed reproducible displacement imaging, and monitoring of twenty two in vitro HIFU treatments using the new 2D system showed a consistent average focal displacement decrease of 46.7±14.6% during lesion formation. Complementary focal temperature monitoring also indicated an average rate of displacement increase and decrease with focal temperature at 0.84±1.15 %/ °C, and 2.03± 0.93%/ °C, respectively. These results reinforce the HMIFU capability of estimating and monitoring stiffness related changes in real time. Current ongoing studies include clinical translation of the presented system for monitoring of HIFU treatment for breast and pancreatic tumor applications. PMID:24960528

  19. 2D/4D marker-free tumor tracking using 4D CBCT as the reference image

    NASA Astrophysics Data System (ADS)

    Wang, Mengjiao; Sharp, Gregory C.; Rit, Simon; Delmon, Vivien; Wang, Guangzhi

    2014-05-01

    Tumor motion caused by respiration is an important issue in image-guided radiotherapy. A 2D/4D matching method between 4D volumes derived from cone beam computed tomography (CBCT) and 2D fluoroscopic images was implemented to track the tumor motion without the use of implanted markers. In this method, firstly, 3DCBCT and phase-rebinned 4DCBCT are reconstructed from cone beam acquisition. Secondly, 4DCBCT volumes and a streak-free 3DCBCT volume are combined to improve the image quality of the digitally reconstructed radiographs (DRRs). Finally, the 2D/4D matching problem is converted into a 2D/2D matching between incoming projections and DRR images from each phase of the 4DCBCT. The diaphragm is used as a target surrogate for matching instead of using the tumor position directly. This relies on the assumption that if a patient has the same breathing phase and diaphragm position as the reference 4DCBCT, then the tumor position is the same. From the matching results, the phase information, diaphragm position and tumor position at the time of each incoming projection acquisition can be derived. The accuracy of this method was verified using 16 candidate datasets, representing lung and liver applications and one-minute and two-minute acquisitions. The criteria for the eligibility of datasets were described: 11 eligible datasets were selected to verify the accuracy of diaphragm tracking, and one eligible dataset was chosen to verify the accuracy of tumor tracking. The diaphragm matching accuracy was 1.88 ± 1.35 mm in the isocenter plane and the 2D tumor tracking accuracy was 2.13 ± 1.26 mm in the isocenter plane. These features make this method feasible for real-time marker-free tumor motion tracking purposes.

  20. Optimal angular dose distribution to acquire 3D and extra 2D images for digital breast tomosynthesis (DBT)

    NASA Astrophysics Data System (ADS)

    Park, Hye-Suk; Kim, Ye-Seul; Lee, Haeng-Hwa; Gang, Won-Suk; Kim, Hee-Joung; Choi, Young-Wook; Choi, JaeGu

    2015-08-01

    The purpose of this study is to determine the optimal non-uniform angular dose distribution to improve the quality of the 3D reconstructed images and to acquire extra 2D projection images. In this analysis, 7 acquisition sets were generated by using four different values for the number of projections (11, 15, 21, and 29) and total angular range (±14°, ±17.5°, ±21°, and ±24.5° ). For all acquisition sets, the zero-degree projection was used as the 2D image that was close to that of standard conventional mammography (CM). Exposures used were 50, 100, 150, and 200 mR for the zero-degree projection, and the remaining dose was distributed over the remaining projection angles. To quantitatively evaluate image quality, we computed the CNR (contrast-to-noise ratio) and the ASF (artifact spread function) for the same radiation dose. The results indicate that, for microcalcifications, acquisition sets with approximately 4 times higher exposure on the zero-degree projection than the average exposure for the remaining projection angles yielded higher CNR values and were 3% higher than the uniform distribution. However, very high dose concentrations toward the zero-degree projection may reduce the quality of the reconstructed images due to increasing noise in the peripheral views. The zero-degree projection of the non-uniform dose distribution offers a 2D image similar to that of standard CM, but with a significantly lower radiation dose. Therefore, we need to evaluate the diagnostic potential of extra 2D projection image when diagnose breast cancer by using 3D images with non-uniform angular dose distributions.

  1. Parallel computation of optimized arrays for 2-D electrical imaging surveys

    NASA Astrophysics Data System (ADS)

    Loke, M. H.; Wilkinson, P. B.; Chambers, J. E.

    2010-12-01

    Modern automatic multi-electrode survey instruments have made it possible to use non-traditional arrays to maximize the subsurface resolution from electrical imaging surveys. Previous studies have shown that one of the best methods for generating optimized arrays is to select the set of array configurations that maximizes the model resolution for a homogeneous earth model. The Sherman-Morrison Rank-1 update is used to calculate the change in the model resolution when a new array is added to a selected set of array configurations. This method had the disadvantage that it required several hours of computer time even for short 2-D survey lines. The algorithm was modified to calculate the change in the model resolution rather than the entire resolution matrix. This reduces the computer time and memory required as well as the computational round-off errors. The matrix-vector multiplications for a single add-on array were replaced with matrix-matrix multiplications for 28 add-on arrays to further reduce the computer time. The temporary variables were stored in the double-precision Single Instruction Multiple Data (SIMD) registers within the CPU to minimize computer memory access. A further reduction in the computer time is achieved by using the computer graphics card Graphics Processor Unit (GPU) as a highly parallel mathematical coprocessor. This makes it possible to carry out the calculations for 512 add-on arrays in parallel using the GPU. The changes reduce the computer time by more than two orders of magnitude. The algorithm used to generate an optimized data set adds a specified number of new array configurations after each iteration to the existing set. The resolution of the optimized data set can be increased by adding a smaller number of new array configurations after each iteration. Although this increases the computer time required to generate an optimized data set with the same number of data points, the new fast numerical routines has made this practical on commonly available microcomputers.

  2. Improved 2-D resistivity imaging of features in covered karst terrain with arrays of implanted electrodes

    NASA Astrophysics Data System (ADS)

    Kiflu, H. G.; Kruse, S. E.; Harro, D.; Loke, M. H.; Wilkinson, P. B.

    2013-12-01

    Electrical resistivity tomography is commonly used to identify geologic features associated with sinkhole formation. In covered karst terrain, however, it can be difficult to resolve the depth to top of limestone with this method. This is due to the fact that array lengths, and hence depth of resolution, are often limited by residential or commercial lot dimensions in urban environments. Furthermore, the sediments mantling the limestone are often clay-rich and highly conductive. The resistivity method has limited sensitivity to resistive zones beneath conductive zones. This sensitivity can be improved significantly with electrodes implanted at depth in the cover sediments near the top of limestone. An array of deep electrodes is installed with direct push technology in the karst cover. When combined with a surface array in which each surface electrode is underlain by a deep electrode, the array geometry is similar to a borehole array turned on its side. This method, called the Multi-Electrode Resistivity Implant Technique (MERIT), offers the promise of significantly improved resolution of epikarst and cover collapse development zones in the overlying sediment, the limestone or at the sediment-bedrock interface in heterogeneous karst environments. With a non-traditional array design, the question of optimal array geometries arises. Optimizing array geometries is complicated by the fact that many plausible 4-electrode readings will produce negative apparent resistivity values, even in homogeneous terrain. Negative apparent resistivities cannot be used in inversions based on the logarithm of the apparent resistivity. New algorithms for seeking optimal array geometries have been developed by modifying the 'Compare R' method of Wilkinson and Loke. The optimized arrays show significantly improved resolution over basic arrays adapted from traditional 2D surface geometries. Several MERIT case study surveys have been conducted in covered karst in west-central Florida, with 28-electrode arrays with electrodes 2-5 meters apart, and the deep arrays buried at 4-8 meters depth. Ground penetrating radar surveys, SPT borings and coring data provide selected 'ground truthing'. The case studies show that inclusion of the deep electrode array permits karst features such as undulations at the top of limestone and raveling zones within surficial sediments to be imaged. These features are not accessible from surface arrays with equivalent surface footprints. The method also has better resolution at depth at the ends of the lines, where surface arrays are typically plotted with a trapezoidal truncation due to poor resolution at the lower corners of the profile.

  3. Development and validation of a modelling framework for simulating 2D-mammography and breast tomosynthesis images.

    PubMed

    Elangovan, Premkumar; Warren, Lucy M; Mackenzie, Alistair; Rashidnasab, Alaleh; Diaz, Oliver; Dance, David R; Young, Kenneth C; Bosmans, Hilde; Strudley, Celia J; Wells, Kevin

    2014-08-01

    Planar 2D x-ray mammography is generally accepted as the preferred screening technique used for breast cancer detection. Recently, digital breast tomosynthesis (DBT) has been introduced to overcome some of the inherent limitations of conventional planar imaging, and future technological enhancements are expected to result in the introduction of further innovative modalities. However, it is crucial to understand the impact of any new imaging technology or methodology on cancer detection rates and patient recall. Any such assessment conventionally requires large scale clinical trials demanding significant investment in time and resources. The concept of virtual clinical trials and virtual performance assessment may offer a viable alternative to this approach. However, virtual approaches require a collection of specialized modelling tools which can be used to emulate the image acquisition process and simulate images of a quality indistinguishable from their real clinical counterparts. In this paper, we present two image simulation chains constructed using modelling tools that can be used for the evaluation of 2D-mammography and DBT systems. We validate both approaches by comparing simulated images with real images acquired using the system being simulated. A comparison of the contrast-to-noise ratios and image blurring for real and simulated images of test objects shows good agreement ( < 9% error). This suggests that our simulation approach is a promising alternative to conventional physical performance assessment followed by large scale clinical trials. PMID:25029333

  4. Development and validation of a modelling framework for simulating 2D-mammography and breast tomosynthesis images

    NASA Astrophysics Data System (ADS)

    Elangovan, Premkumar; Warren, Lucy M.; Mackenzie, Alistair; Rashidnasab, Alaleh; Diaz, Oliver; Dance, David R.; Young, Kenneth C.; Bosmans, Hilde; Strudley, Celia J.; Wells, Kevin

    2014-08-01

    Planar 2D x-ray mammography is generally accepted as the preferred screening technique used for breast cancer detection. Recently, digital breast tomosynthesis (DBT) has been introduced to overcome some of the inherent limitations of conventional planar imaging, and future technological enhancements are expected to result in the introduction of further innovative modalities. However, it is crucial to understand the impact of any new imaging technology or methodology on cancer detection rates and patient recall. Any such assessment conventionally requires large scale clinical trials demanding significant investment in time and resources. The concept of virtual clinical trials and virtual performance assessment may offer a viable alternative to this approach. However, virtual approaches require a collection of specialized modelling tools which can be used to emulate the image acquisition process and simulate images of a quality indistinguishable from their real clinical counterparts. In this paper, we present two image simulation chains constructed using modelling tools that can be used for the evaluation of 2D-mammography and DBT systems. We validate both approaches by comparing simulated images with real images acquired using the system being simulated. A comparison of the contrast-to-noise ratios and image blurring for real and simulated images of test objects shows good agreement ( < 9% error). This suggests that our simulation approach is a promising alternative to conventional physical performance assessment followed by large scale clinical trials.

  5. Simultaneous 2D imaging of dissolved iron and reactive phosphorus in sediment porewaters by thin-film and hyperspectral methods.

    PubMed

    Cesbron, Florian; Metzger, Edouard; Launeau, Patrick; Deflandre, Bruno; Delgard, Marie-Lise; Thibault de Chanvalon, Aubin; Geslin, Emmanuelle; Anschutz, Pierre; Jézéquel, Didier

    2014-01-01

    This study presents a new approach combining diffusive equilibrium in thin-film (DET) and spectrophotometric methods to determine the spatial variability of dissolved iron and dissolved reactive phosphorus (DRP) with a single gel probe. Its originality is (1) to postpone up to three months the colorimetric reaction of DET by freezing and (2) to measure simultaneously dissolved iron and DRP by hyperspectral imaging at a submillimeter resolution. After a few minutes at room temperature, the thawed gel is sandwiched between two monospecific reagent DET gels, leading to magenta and blue coloration for iron and phosphate, respectively. Spatial distribution of the resulting colors is obtained using a hyperspectral camera. Reflectance spectra analysis enables deconvolution of specific colorations by the unmixing method applied to the logarithmic reflectance, leading to an accurate quantification of iron and DRP. This method was applied in the Arcachon lagoon (France) on muddy sediments colonized by eelgrass (Zostera noltei) meadows. The 2D gel probes highlighted microstructures in the spatial distribution of dissolved iron and phosphorus, which are most likely associated with the occurrence of benthic fauna burrows and seagrass roots. PMID:24502458

  6. 2-D Precise Radiation Mapping of Sedimentary Core Using Imaging Plate

    NASA Astrophysics Data System (ADS)

    Sugihara, M.; Tsuchiya, N.

    2006-12-01

    The imaging plate (IP) is a storage film coated with photostimulated phosphor (BaFBr: Eu2+), and the latent images produced by irradiation of the imaging plate are read by superficial scanning with stimulation light and are reconstructed as two-dimensional dot images on a computer display. It has an excellent performance for radiation detection, and its advantages include an ease of use, a high position resolution (up to 25ƒÊm), a large detection area (up to 35'43cm2), a high detection sensitivity with high signal-to- noise ratio, an extremely wide dynamic range of dose, a sensitivity to several kinds of radiation, and an erasing capability for reuse (Hareyama et al., 2000). In this study, in order to develop a nondestructive, precise and large area evaluation method of sedimentary structure, an application of autoradiography using IP is attempted to marine sediments. Imaging plate (BAS-MS2040 Fujifilm Co. Ltd., 20'~40 cm2) was cut into rectangular five pieces (4'~40 cm2). Whole round marine sedimentary cores were divided into two half for duplicate and they were covered with a plastic wrap. The rectangular IP were put along the center line of plane side of half round. The exposure in the low temperature was for 48 hours in a shield box. The latent images produced by irradiation of the IP were read out by using the BAS-2500 imaging analyzer (Fujifilm Co. Ltd.). Radiation dose of IP is output as PSL value, that is unique dose units and quantities of IP system. Position resolution was set to 50ƒÊm. Marine sedimentary cores including volcanic ash layer were measured using IP and Natural Gamma Logger (NGL), which is measuring instrument for marine sediments in practice use, to compare their measuring ability. As a result of experiment, it becomes clear that high dose distribution is found at volcanic ash layer with IP, meanwhile it can't be found with NGL. The content of radiation source in volcanic ash layer is supposed to be high compared with other layers because minerals tend to have more potassium, uranium and other radioactive elements than other layer components, for example, organic materials and biotic shells. It can be said that IP has high position resolution and detection sensitivity to figure out the dose distribution from volcanic ash layer. In order to understand relationships between dose and physical properties of marine sedimentary cores, several cores were measured using IP, Multi Sensor Core Logger (MSCL), and X-ray CT scanner. Density, p- wave velocity, resistivity, and magnetic susceptibility were measured by using MSCL, and density showed a good relation with PSL value. Although X-ray CT Scanner is used for visualization of cores, in order to compare the result of CT with the result of IP numerically, CT value that depends on density of materials is used. As a result of it, CT value showed a good relation with PSL value and taken into the dependence of CT value on density and the result of MSCL, it can be said that there is a strong dependence of dose on density in marine sediments.

  7. Initial Images of the Synthetic Aperture Radiometer 2D-STAR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Initial results obtained using a new synthetic aperture radiometer, 2D-STAR, a dual polarized, L-band radiometer that employs aperture synthesis in two dimensions are presented and analyzed. This airborne instrument is the natural evolution of a previous design that employed employs aperture synthes...

  8. A Monte Carlo simulation of steady state of 2D Ising model in temperature field

    NASA Astrophysics Data System (ADS)

    Chen, Zeshun; Xiao, Changming; Yao, Zhen

    2016-01-01

    Supposing the Ising model system is placed in a temperature field with constant high and low temperatures on both sides, then the system will shift to a non-equilibrium steady state with a certain temperature gradient. With the assistance of local temperature, the steady state of two-dimensional Ising model is studied via the avenue of Monte Carlo simulations in this paper. It is found that the local energy and magnetization are continuous, but there is a sharp decline in the magnetization strength when the temperature falls into the range of 2.2-2.4. The local magnetization |M| > 0, when the temperature T < 2.3. It is the indication that the system is in the ferromagnetic state. However, when T > 2.35, M → 0, and then the ferromagnetic state turns into the paramagnetic state. Furthermore, a completely new and special state of Ising model system and the corresponding material is possible if the high and low temperatures of the temperature field are larger and smaller than the critical value of the system, respectively. According to this material, the magnetic driving machine, from which a new energy source can be obtained, is qualitatively discussed at the end of this paper.

  9. Temperature Effects on the Wind Direction Measurement of 2D Solid Thermal Wind Sensors

    PubMed Central

    Chen, Bei; Zhu, Yan-Qing; Yi, Zhenxiang; Qin, Ming; Huang, Qing-An

    2015-01-01

    For a two-dimensional solid silicon thermal wind sensor with symmetrical structure, the wind speed and direction information can be derived from the output voltages in two orthogonal directions, i.e., the north-south and east-west. However, the output voltages in these two directions will vary linearly with the ambient temperature. Therefore, in this paper, a temperature model to study the temperature effect on the wind direction measurement has been developed. A theoretical analysis has been presented first, and then Finite Element Method (FEM) simulations have been performed. It is found that due to symmetrical structure of the thermal wind sensor, the temperature effects on the output signals in the north-south and east-west directions are highly similar. As a result, the wind direction measurement of the thermal wind sensor is approximately independent of the ambient temperature. The experimental results fit the theoretical analysis and simulation results very well. PMID:26633398

  10. High-resolution mapping of 1D and 2D dose distributions using X-band electron paramagnetic resonance imaging.

    PubMed

    Kolbun, N; Adolfsson, E; Gustafsson, H; Lund, E

    2014-06-01

    Electron paramagnetic resonance imaging (EPRI) was performed to visualise 2D dose distributions of homogenously irradiated potassium dithionate tablets and to demonstrate determination of 1D dose profiles along the height of the tablets. Mathematical correction was applied for each relative dose profile in order to take into account the inhomogeneous response of the resonator using X-band EPRI. The dose profiles are presented with the spatial resolution of 0.6 mm from the acquired 2D images; this value is limited by pixel size, and 1D dose profiles from 1D imaging with spatial resolution of 0.3 mm limited by the intrinsic line-width of potassium dithionate. In this paper, dose profiles from 2D reconstructed electron paramagnetic resonance (EPR) images using the Xepr software package by Bruker are focussed. The conclusion is that using potassium dithionate, the resolution 0.3 mm is sufficient for mapping steep dose gradients if the dosemeters are covering only ±2 mm around the centre of the resonator. PMID:24748487

  11. 2D grating simulation for X-ray phase-contrast and dark-field imaging with a Talbot interferometer

    SciTech Connect

    Zanette, Irene; Weitkamp, Timm; David, Christian; Rutishauser, Simon

    2010-04-06

    Talbot interferometry is a recently developed and an extremely powerful X-ray phase-contrast imaging technique. Besides giving access to ultra-high sensitivity differential phase contrast images, it also provides the dark field image, which is a map of the scattering power of the sample. In this paper we investigate the potentialities of an improved version of the interferometer, in which two dimensional gratings are used instead of standard line grids. This approach allows to overcome the difficulties that might be encountered in the images produced by a one dimensional interferometer. Among these limitations there are the phase wrapping and quantitative phase retrieval problems and the directionality of the differential phase and dark-field signals. The feasibility of the 2D Talbot interferometer has been studied with a numerical simulation on the performances of its optical components under different circumstances. The gratings can be obtained either by an ad hoc fabrication of the 2D structures or by a superposition of two perpendicular linear grids. Through this simulation it has been possible to find the best parameters for a practical implementation of the 2D Talbot interferometer.

  12. Generalized 2-D Principal Component Analysis by Lp-Norm for Image Analysis.

    PubMed

    Wang, Jing

    2016-03-01

    This paper proposes a generalized 2-D principal component analysis (G2DPCA) by replacing the L2-norm in conventional 2-D principal component analysis (2DPCA) with Lp-norm, both in objective and constraint functions. It is a generalization of previously proposed robust or sparse 2DPCA algorithms. Under the framework of minorization-maximization, we design an iterative algorithm to solve the optimization problem of G2DPCA. A closed-form solution could be obtained in each iteration. Then a deflating scheme is employed to generate multiple projection vectors. Our algorithm guarantees to find a locally optimal solution for G2DPCA. The effectiveness of the proposed method is experimentally verified. PMID:25898326

  13. In-plane magnetic field versus temperature phase diagram of a quasi-2D frustrated multiband superconductor

    NASA Astrophysics Data System (ADS)

    Marques, A. M.; Dias, R. G.; Araújo, M. A. N.; Santos, F. D. R.

    2015-04-01

    Motivated by the recent discovery of iron-based superconductors, with high critical temperatures and multiple bands crossing the Fermi level, we address the conditions for the presence of chiral superconducting phases configurations in the in-plane magnetic field versus temperature phase diagram of a quasi-2D frustrated three-band superconductor. Due to Zeeman splitting, the coupled superconducting gap equations present a complex set of solutions. For weak interband couplings, chiral configurations are only attained in a narrow strip of the in-plane magnetic field versus temperature phase diagram. This strip of chiral states becomes narrower and disappears at low temperatures, giving way to a first-order transition between non-chiral superconducting states. For stronger interband couplings, the chiral strip is much broader, if the interband couplings are approximately equal; otherwise, the chiral region is expected to be completely absent of the phase diagram.

  14. 2-D Fused Image Reconstruction approach for Microwave Tomography: a theoretical assessment using FDTD Model.

    PubMed

    Bindu, G; Semenov, S

    2013-01-01

    This paper describes an efficient two-dimensional fused image reconstruction approach for Microwave Tomography (MWT). Finite Difference Time Domain (FDTD) models were created for a viable MWT experimental system having the transceivers modelled using thin wire approximation with resistive voltage sources. Born Iterative and Distorted Born Iterative methods have been employed for image reconstruction with the extremity imaging being done using a differential imaging technique. The forward solver in the imaging algorithm employs the FDTD method of solving the time domain Maxwell's equations with the regularisation parameter computed using a stochastic approach. The algorithm is tested with 10% noise inclusion and successful image reconstruction has been shown implying its robustness. PMID:24058889

  15. Echogenicity based approach to detect, segment and track the common carotid artery in 2D ultrasound images.

    PubMed

    Narayan, Nikhil S; Marziliano, Pina

    2015-08-01

    Automatic detection and segmentation of the common carotid artery in transverse ultrasound (US) images of the thyroid gland play a vital role in the success of US guided intervention procedures. We propose in this paper a novel method to accurately detect, segment and track the carotid in 2D and 2D+t US images of the thyroid gland using concepts based on tissue echogenicity and ultrasound image formation. We first segment the hypoechoic anatomical regions of interest using local phase and energy in the input image. We then make use of a Hessian based blob like analysis to detect the carotid within the segmented hypoechoic regions. The carotid artery is segmented by making use of least squares ellipse fit for the edge points around the detected carotid candidate. Experiments performed on a multivendor dataset of 41 images show that the proposed algorithm can segment the carotid artery with high sensitivity (99.6 ±m 0.2%) and specificity (92.9 ±m 0.1%). Further experiments on a public database containing 971 images of the carotid artery showed that the proposed algorithm can achieve a detection accuracy of 95.2% with a 2% increase in performance when compared to the state-of-the-art method. PMID:26736920

  16. A challenge problem for 2D/3D imaging of targets from a volumetric data set in an urban environment

    NASA Astrophysics Data System (ADS)

    Casteel, Curtis H., Jr.; Gorham, LeRoy A.; Minardi, Michael J.; Scarborough, Steven M.; Naidu, Kiranmai D.; Majumder, Uttam K.

    2007-04-01

    This paper describes a challenge problem whose scope is the 2D/3D imaging of stationary targets from a volumetric data set of X-band Synthetic Aperture Radar (SAR) data collected in an urban environment. The data for this problem was collected at a scene consisting of numerous civilian vehicles and calibration targets. The radar operated in circular SAR mode and completed 8 circular flight paths around the scene with varying altitudes. Data consists of phase history data, auxiliary data, processing algorithms, processed images, as well as ground truth data. Interest is focused on mitigating the large side lobes in the point spread function. Due to the sparse nature of the elevation aperture, traditional imaging techniques introduce excessive artifacts in the processed images. Further interests include the formation of highresolution 3D SAR images with single pass data and feature extraction for 3D SAR automatic target recognition applications. The purpose of releasing the Gotcha Volumetric SAR Data Set is to provide the community with X-band SAR data that supports the development of new algorithms for high-resolution 2D/3D imaging.

  17. 2D photochemical modeling of Saturn's stratosphere. Part II: Feedback between composition and temperature

    NASA Astrophysics Data System (ADS)

    Hue, V.; Greathouse, T. K.; Cavalié, T.; Dobrijevic, M.; Hersant, F.

    2016-03-01

    Saturn's axial tilt of 26.7° produces seasons in a similar way as on Earth. Both the stratospheric temperature and composition are affected by this latitudinally varying insolation along Saturn's orbital path. The atmospheric thermal structure is controlled and regulated by the amount of hydrocarbons in the stratosphere, which act as absorbers and coolants from the UV to the far-IR spectral range, and this structure has an influence on the amount of hydrocarbons. We study here the feedback between the chemical composition and the thermal structure by coupling a latitudinal and seasonal photochemical model with a radiative seasonal model. Our results show that the seasonal temperature peak in the higher stratosphere, associated with the seasonal increase of insolation, is shifted earlier than the maximum insolation peak. This shift is increased with increasing latitudes and is caused by the low amount of stratospheric coolants in the spring season. At 80° in both hemispheres, the temperature peak at 10-2 mbar is seen to occur half a season (3-4 Earth years) earlier than was previously predicted by radiative seasonal models that assumed spatially and temporally uniform distribution of coolants. This shift progressively decreases with increasing pressure, up to around the 0.5 mbar pressure level where it vanishes. On the opposite, the thermal field has a small feedback on the abundance distributions. Accounting for that feedback modifies the predicted equator-to-pole temperature gradient. The meridional gradients of temperature at the mbar pressure levels are better reproduced when this feedback is accounted for. At lower pressure levels, Saturn's stratospheric thermal structure seems to depart from pure radiative seasonal equilibrium as previously suggested by Guerlet et al. (2014). Although the agreement with the absolute value of the stratospheric temperature observed by Cassini is moderate, it is a mandatory step toward a fully coupled GCM-photochemical model.

  18. Estimation of the Lateral Ventricles Volumes from a 2D Image and Its Relationship with Cerebrospinal Fluid Flow

    PubMed Central

    Bader, Chaarani; Cyrille, Capel; Jadwiga, Zmudka; Joel, Daouk; Fichten, Anthony; Catherine, Gondry-Jouet; Roger, Bouzerar; Olivier, Balédent

    2013-01-01

    Purpose. This work suggests a fast estimation method of the lateral ventricles volume from a 2D image and then determines if this volume is correlated with the cerebrospinal fluid flow at the aqueductal and cerebral levels in neurodegenerative diseases. Materials and Methods. FForty-five elderly patients suffering from Alzheimer's disease (19), normal pressure hydrocephalus (13), and vascular dementia (13) were involved and underwent anatomical and phase contrast MRI scans. Lateral ventricles and stroke volumes were assessed on anatomical and phase contrast scans, respectively. A common reference plane was used to calculate the lateral ventricles' area on 2D images. Results. The largest volumes were observed in hydrocephalus patients. The linear regression between volumes and areas was computed, and a strong positive correlation was detected (R2 = 0.9). A derived equation was determined to represent the volumes for any given area. On the other hand, no significant correlations were detected between ventricles and stroke volumes (R2 ≤ 0.15). Conclusion. Lateral ventricles volumes are significantly proportional to the 2D reference section area and could be used for patients' follow-up even if 3D images are unavailable. The cerebrospinal fluid fluctuations in brain disorders may depend on many physiological parameters other than the ventricular morphology. PMID:24151585

  19. Effects of postmortem storage temperature on sea bass (Dicentrarchus labrax) muscle protein degradation: analysis by 2-D DIGE and MS.

    PubMed

    Terova, Genciana; Addis, Maria Filippa; Preziosa, Elena; Pisanu, Salvatore; Pagnozzi, Daniela; Biosa, Grazia; Gornati, Rosalba; Bernardini, Giovanni; Roggio, Tonina; Saroglia, Marco

    2011-07-01

    Storage conditions are known to be important for postmortem deterioration of fish muscle, and temperature is one of the factors with the strongest impact on this process. In order to shed light on the influence of temperature on the status of sea bass (Dicentrarchus labrax) muscle proteins during postmortem storage, a 2-D DIGE and mass spectrometry study was performed on fish kept at either 1 or 18°C for 5 days. As expected, the greatest alterations in sea bass filet protein composition were observed upon postmortem storage at 18°C, with distinct changes appearing in the 2-D protein profile after 5 days of storage at this temperature. In particular, degradation of the myofibrillar protein myosin heavy chain and of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase, among the most abundant muscle proteins, could be clearly observed upon storage at higher temperatures. Although to a lesser extent, however, several proteins were observed to vary in abundance also upon storage for 5 days at 1°C. In particular, one of the most interesting observations was the rapid and significant decrease in the abundance of nucleoside diphosphate kinase B and phosphoglycerate mutase 2, which was observed also at low storage temperatures and appeared to be temperature-independent. The results of this study offer new knowledge on changes occurring in sea bass muscle proteins during postmortem storage at different temperatures and provide indications on protein degradation trends that might be useful for monitoring freshness of fish and quality of storage conditions. PMID:21656684

  20. Imaging-based amplitude laser beam shaping for material processing by 2D reflectivity tuning of a spatial light modulator.

    PubMed

    Li, Jiangning; Kuang, Zheng; Edwardson, Stuart; Perrie, Walter; Liu, Dun; Dearden, Geoff

    2016-02-10

    We have demonstrated an imaging-based amplitude laser-beam-shaping technique for material processing by 2D reflectivity tuning of a spatial light modulator. Intensity masks with 256 gray levels were designed to shape the input laser beam in the outline profile and inside intensity distribution. Squared and circular flattop beam shapes were obtained at the diffractive near-field and then reconstructed at an image plane of an f-theta lens (f∼100  mm). The observed intensity distribution inside the beam-shaping geometry was much more even than using binary masks. The ablation footprint well matches the desired beam shape. PMID:26906382

  1. Edge effect and significant increase of the superconducting transition onset temperature of 2D superconductors in flat and curved geometries

    NASA Astrophysics Data System (ADS)

    Wong, Chi Ho; Lortz, Rolf

    2016-02-01

    In this paper, we present a simple method to model the curvature activated phonon softening in a 2D superconducting layer. The superconducting transition temperature Tc in the case of a 2D rectangular sheet, a hollow cylinder and a hollow sphere of one coherence length thickness is calculated by the quantum mechanical electron-phonon scattering matrix, and a series of collective lattice vibrations in the surface state. We will show that being extremely thin in a flat rectangular shape is not enough to significantly enhance the Tc through phonon softening. However, if a curvature is added, Tc can be strongly enhanced. The increase in Tc with respect to the bulk is greatest in a hollow sphere, intermediate in a hollow cylinder and weakest for the rectangular sheet, when systems of identical length scale are considered. In addition, we find that the edge effect of such a 2D sheet has a strong broadening effect on Tc in addition to the effect of order parameter phase fluctuations.

  2. Segmentation of 2D fetal ultrasound images by exploiting context information using conditional random fields.

    PubMed

    Gupta, Lalit; Sisodia, Rajendra Singh; Pallavi, V; Firtion, Celine; Ramachandran, Ganesan

    2011-01-01

    This paper proposes a novel approach for segmenting fetal ultrasound images. This problem presents a variety of challenges including high noise, low contrast, and other US imaging properties such as similarity between texture and gray levels of two organs/ tissues. In this paper, we have proposed a Conditional Random Field (CRF) based framework to handle challenges in segmenting fetal ultrasound images. Clinically, it is known that fetus is surrounded by specific maternal tissues, amniotic fluid and placenta. We exploit this context information using CRFs for segmenting the fetal images accurately. The proposed CRF framework uses wavelet based texture features for representing the ultrasound image and Support Vector Machines (SVM) for initial label prediction. Initial results on a limited dataset of real world ultrasound images of fetus are promising. Results show that proposed method could handle the noise and similarity between fetus and its surroundings in ultrasound images. PMID:22256004

  3. Estimating elastic moduli of rocks from thin sections: Digital rock study of 3D properties from 2D images

    NASA Astrophysics Data System (ADS)

    Saxena, Nishank; Mavko, Gary

    2016-03-01

    Estimation of elastic rock moduli using 2D plane strain computations from thin sections has several numerical and analytical advantages over using 3D rock images, including faster computation, smaller memory requirements, and the availability of cheap thin sections. These advantages, however, must be weighed against the estimation accuracy of 3D rock properties from thin sections. We present a new method for predicting elastic properties of natural rocks using thin sections. Our method is based on a simple power-law transform that correlates computed 2D thin section moduli and the corresponding 3D rock moduli. The validity of this transform is established using a dataset comprised of FEM-computed elastic moduli of rock samples from various geologic formations, including Fontainebleau sandstone, Berea sandstone, Bituminous sand, and Grossmont carbonate. We note that using the power-law transform with a power-law coefficient between 0.4-0.6 contains 2D moduli to 3D moduli transformations for all rocks that are considered in this study. We also find that reliable estimates of P-wave (Vp) and S-wave velocity (Vs) trends can be obtained using 2D thin sections.

  4. Finite element nonlinear flutter and fatigue life of 2-D panels with temperature effects

    NASA Technical Reports Server (NTRS)

    Mei, Chuh; Xue, David Y.

    1991-01-01

    A frequency domain method for two-dimensional nonlinear panel flutter with thermal effects obtained from a consistent finite element formulation is presented. The von Karman nonlinear strain-displacement relation is used to account for large deflections, and the quasi-steady first-order piston theory is employed for aerodynamic loading. The finite element frequency domain results are compared with analytical time domain solutions. In a limit-cycle motion, the panel frequency and stress can be determined, thus fatigue life can be predicted. The influence of temperature and dynamic pressure on panel fatigue life is presented. An endurance dynamic pressure can be established at a given temperature from the present method.

  5. New insights in a 2-D hard disk system under a temperature gradient

    NASA Astrophysics Data System (ADS)

    del Pozo, J. J.; Pérez-Espigares, C.; Hurtado, P. I.; Garrido, P. L.

    2011-03-01

    Hard Disks system is a paradicmatic model well suited, numericaly, to test new approaches to nonequi-librium fenomena, being also easy and fast to simulate due to efficient event driven algorithms present in the literature. In this poster we study several properties of the model under a temperature gradient on the stationary regime. In this situation the sistem has well defined gradients in temperatures and densities allowing us to calculate experimentaly the thermal conductivity. We found this result compatible with the Enskog expresion even for large gradients. We also check that Henderson's state equation, although is an expresion derived under equilibrium conditions, is valid in our system for a wide range of temperatures gradients. We explain this fact showing that the system reach a local thermal equilibrium. Finaly we focus on the role of fluctuations of the energy current finding good agreement with the, recently introduced, Isometric Fluctuation Relation (IFR). We conclude that IFR also stands in our system, although it was formulated from a much simpler case.

  6. A comparison of 2D and 3D evaluation methods for pulmonary embolism detection in CT images

    NASA Astrophysics Data System (ADS)

    Kiraly, Atilla P.; Novak, Carol L.; Naidich, David P.; Vlahos, Ioannis; Ko, Jane P.; Brusca-Augello, Geraldine T.

    2006-03-01

    Pulmonary embolism (PE) is a life-threatening disease, requiring rapid diagnosis and treatment. Contrast enhanced computed tomographic (CT) images of the lungs allow physicians to confirm or rule out PE, but the large number of images per study and the complexity of lung anatomy may cause some emboli to be overlooked. We evaluated a novel three-dimensional (3D) visualization technique for detecting PE, and compared it with traditional 2D axial interpretation. Three readers independently marked 10 cases using the 3D method, and a separate interpretation was performed at a later date using only source axial images. An experienced thoracic radiologist adjudicated all marks, classifying clots according to location and confidence. There were a total of 8 positive examinations with 69 validated emboli. 44 (64%) of the clots were segmental while 12 (17%) proved subsegmental. Using the traditional 2D method for examination, readers detected a mean of 45 PE for 66% sensitivity. Using the 3D method, readers detected a mean of 35 PE (50% sensitivity). Combining both methods, readers detected a mean of 51 PE (74% sensitivity), significantly higher than either single method (p<0.001). Considered by arterial level, significant improvement was observed for detection of segmental and subsegmental clots (p<0.001) when comparing combined reading with either single method. The mean number of false positives per patient was 0.23 for both 2D and 3D readings and 0.4 for combined reading. 3D visualization of pulmonary arteries allowed readers to detect a significant number of additional emboli not detected during 2D axial interpretations and thus may lead to a more accurate diagnosis of PE.

  7. Direct observation of ground-state lactam-lactim tautomerization using temperature-jump transient 2D IR spectroscopy.

    PubMed

    Peng, Chunte Sam; Baiz, Carlos R; Tokmakoff, Andrei

    2013-06-01

    We provide a systematic characterization of the nanosecond ground-state lactam-lactim tautomerization of pyridone derivatives in aqueous solution under ambient conditions using temperature-jump transient 2D IR spectroscopy. Although electronic excited-state tautomerization has been widely studied, experimental work on the ground electronic state, most relevant to chemistry and biology, is lacking. Using 2D IR spectroscopy, lactam and lactim tautomers of 6-chloro-2-pyridone and 2-chloro-4-pyridone are unambiguously identified by their unique cross-peak patterns. Monitoring the correlated exponential relaxation of these signals in response to a laser temperature jump provides a direct measurement of the nanosecond tautomerization kinetics. By studying the temperature, concentration, solvent, and pH dependence, we extract a thermodynamic and kinetic characterization and conclude that the tautomerization proceeds through a two-state concerted mechanism. We find that the intramolecular proton transfer is mediated by bridging water molecules and the reaction barrier is dictated by the release of a proton from pyridone, as would be expected for an efficient Grothuss-type proton transfer mechanism. PMID:23690588

  8. 2D-3D registration for prostate radiation therapy based on a statistical model of transmission images

    SciTech Connect

    Munbodh, Reshma; Tagare, Hemant D.; Chen Zhe; Jaffray, David A.; Moseley, Douglas J.; Knisely, Jonathan P. S.; Duncan, James S.

    2009-10-15

    Purpose: In external beam radiation therapy of pelvic sites, patient setup errors can be quantified by registering 2D projection radiographs acquired during treatment to a 3D planning computed tomograph (CT). We present a 2D-3D registration framework based on a statistical model of the intensity values in the two imaging modalities. Methods: The model assumes that intensity values in projection radiographs are independently but not identically distributed due to the nonstationary nature of photon counting noise. Two probability distributions are considered for the intensity values: Poisson and Gaussian. Using maximum likelihood estimation, two similarity measures, maximum likelihood with a Poisson (MLP) and maximum likelihood with Gaussian (MLG), distribution are derived. Further, we investigate the merit of the model-based registration approach for data obtained with current imaging equipment and doses by comparing the performance of the similarity measures derived to that of the Pearson correlation coefficient (ICC) on accurately collected data of an anthropomorphic phantom of the pelvis and on patient data. Results: Registration accuracy was similar for all three similarity measures and surpassed current clinical requirements of 3 mm for pelvic sites. For pose determination experiments with a kilovoltage (kV) cone-beam CT (CBCT) and kV projection radiographs of the phantom in the anterior-posterior (AP) view, registration accuracies were 0.42 mm (MLP), 0.29 mm (MLG), and 0.29 mm (ICC). For kV CBCT and megavoltage (MV) AP portal images of the same phantom, registration accuracies were 1.15 mm (MLP), 0.90 mm (MLG), and 0.69 mm (ICC). Registration of a kV CT and MV AP portal images of a patient was successful in all instances. Conclusions: The results indicate that high registration accuracy is achievable with multiple methods including methods that are based on a statistical model of a 3D CT and 2D projection images.

  9. Registration of 2D C-Arm and 3D CT Images for a C-Arm Image-Assisted Navigation System for Spinal Surgery

    PubMed Central

    Chang, Chih-Ju; Lin, Geng-Li; Tse, Alex; Chu, Hong-Yu; Tseng, Ching-Shiow

    2015-01-01

    C-Arm image-assisted surgical navigation system has been broadly applied to spinal surgery. However, accurate path planning on the C-Arm AP-view image is difficult. This research studies 2D-3D image registration methods to obtain the optimum transformation matrix between C-Arm and CT image frames. Through the transformation matrix, the surgical path planned on preoperative CT images can be transformed and displayed on the C-Arm images for surgical guidance. The positions of surgical instruments will also be displayed on both CT and C-Arm in the real time. Five similarity measure methods of 2D-3D image registration including Normalized Cross-Correlation, Gradient Correlation, Pattern Intensity, Gradient Difference Correlation, and Mutual Information combined with three optimization methods including Powell's method, Downhill simplex algorithm, and genetic algorithm are applied to evaluate their performance in converge range, efficiency, and accuracy. Experimental results show that the combination of Normalized Cross-Correlation measure method with Downhill simplex algorithm obtains maximum correlation and similarity in C-Arm and Digital Reconstructed Radiograph (DRR) images. Spine saw bones are used in the experiment to evaluate 2D-3D image registration accuracy. The average error in displacement is 0.22 mm. The success rate is approximately 90% and average registration time takes 16 seconds. PMID:27018859

  10. Soft-tissues Image Processing: Comparison of Traditional Segmentation Methods with 2D active Contour Methods

    NASA Astrophysics Data System (ADS)

    Mikulka, J.; Gescheidtova, E.; Bartusek, K.

    2012-01-01

    The paper deals with modern methods of image processing, especially image segmentation, classification and evaluation of parameters. It focuses primarily on processing medical images of soft tissues obtained by magnetic resonance tomography (MR). It is easy to describe edges of the sought objects using segmented images. The edges found can be useful for further processing of monitored object such as calculating the perimeter, surface and volume evaluation or even three-dimensional shape reconstruction. The proposed solutions can be used for the classification of healthy/unhealthy tissues in MR or other imaging. Application examples of the proposed segmentation methods are shown. Research in the area of image segmentation focuses on methods based on solving partial differential equations. This is a modern method for image processing, often called the active contour method. It is of great advantage in the segmentation of real images degraded by noise with fuzzy edges and transitions between objects. In the paper, results of the segmentation of medical images by the active contour method are compared with results of the segmentation by other existing methods. Experimental applications which demonstrate the very good properties of the active contour method are given.

  11. 2D and 3D MALDI-imaging: conceptual strategies for visualization and data mining.

    PubMed

    Thiele, Herbert; Heldmann, Stefan; Trede, Dennis; Strehlow, Jan; Wirtz, Stefan; Dreher, Wolfgang; Berger, Judith; Oetjen, Janina; Kobarg, Jan Hendrik; Fischer, Bernd; Maass, Peter

    2014-01-01

    3D imaging has a significant impact on many challenges in life sciences, because biology is a 3-dimensional phenomenon. Current 3D imaging-technologies (various types MRI, PET, SPECT) are labeled, i.e. they trace the localization of a specific compound in the body. In contrast, 3D MALDI mass spectrometry-imaging (MALDI-MSI) is a label-free method imaging the spatial distribution of molecular compounds. It complements 3D imaging labeled methods, immunohistochemistry, and genetics-based methods. However, 3D MALDI-MSI cannot tap its full potential due to the lack of statistical methods for analysis and interpretation of large and complex 3D datasets. To overcome this, we established a complete and robust 3D MALDI-MSI pipeline combined with efficient computational data analysis methods for 3D edge preserving image denoising, 3D spatial segmentation as well as finding colocalized m/z values, which will be reviewed here in detail. Furthermore, we explain, why the integration and correlation of the MALDI imaging data with other imaging modalities allows to enhance the interpretation of the molecular data and provides visualization of molecular patterns that may otherwise not be apparent. Therefore, a 3D data acquisition workflow is described generating a set of 3 different dimensional images representing the same anatomies. First, an in-vitro MRI measurement is performed which results in a three-dimensional image modality representing the 3D structure of the measured object. After sectioning the 3D object into N consecutive slices, all N slices are scanned using an optical digital scanner, enabling for performing the MS measurements. Scanning the individual sections results into low-resolution images, which define the base coordinate system for the whole pipeline. The scanned images conclude the information from the spatial (MRI) and the mass spectrometric (MALDI-MSI) dimension and are used for the spatial three-dimensional reconstruction of the object performed by image registration techniques. Different strategies for automatic serial image registration applied to MS datasets are outlined in detail. The third image modality is histology driven, i.e. a digital scan of the histological stained slices in high-resolution. After fusion of reconstructed scan images and MRI the slice-related coordinates of the mass spectra can be propagated into 3D-space. After image registration of scan images and histological stained images, the anatomical information from histology is fused with the mass spectra from MALDI-MSI. As a result of the described pipeline we have a set of 3 dimensional images representing the same anatomies, i.e. the reconstructed slice scans, the spectral images as well as corresponding clustering results, and the acquired MRI. Great emphasis is put on the fact that the co-registered MRI providing anatomical details improves the interpretation of 3D MALDI images. The ability to relate mass spectrometry derived molecular information with in vivo and in vitro imaging has potentially important implications. This article is part of a Special Issue entitled: Computational Proteomics in the Post-Identification Era. Guest Editors: Martin Eisenacher and Christian Stephan. PMID:23467008

  12. 2D and 3D imaging resolution trade-offs in quantifying pore throats for prediction of permeability

    SciTech Connect

    Beckingham, Lauren E.; Peters, Catherine A.; Um, Wooyong; Jones, Keith W.; Lindquist, W.Brent

    2013-09-03

    Although the impact of subsurface geochemical reactions on porosity is relatively well understood, changes in permeability remain difficult to estimate. In this work, pore-network modeling was used to predict permeability based on pore- and pore-throat size distributions determined from analysis of 2D scanning electron microscopy (SEM) images of thin sections and 3D X-ray computed microtomography (CMT) data. The analyzed specimens were a Viking sandstone sample from the Alberta sedimentary basin and an experimental column of reacted Hanford sediments. For the column, a decrease in permeability due to mineral precipitation was estimated, but the permeability estimates were dependent on imaging technique and resolution. X-ray CT imaging has the advantage of reconstructing a 3D pore network while 2D SEM imaging can easily analyze sub-grain and intragranular variations in mineralogy. Pore network models informed by analyses of 2D and 3D images at comparable resolutions produced permeability esti- mates with relatively good agreement. Large discrepancies in predicted permeabilities resulted from small variations in image resolution. Images with resolutions 0.4 to 4 lm predicted permeabilities differ- ing by orders of magnitude. While lower-resolution scans can analyze larger specimens, small pore throats may be missed due to resolution limitations, which in turn overestimates permeability in a pore-network model in which pore-to-pore conductances are statistically assigned. Conversely, high-res- olution scans are capable of capturing small pore throats, but if they are not actually flow-conducting predicted permeabilities will be below expected values. In addition, permeability is underestimated due to misinterpreting surface-roughness features as small pore throats. Comparison of permeability pre- dictions with expected and measured permeability values showed that the largest discrepancies resulted from the highest resolution images and the best predictions of permeability will result from images between 2 and 4 lm resolution. To reduce permeability underestimation from analyses of high-resolu- tion images, a resolution threshold between 3 and 15 lm was found to be effective, but it is not known whether this range is applicable beyond the samples studied here.

  13. Study of the electrical conductivity at finite temperature in 2D Si- MOSFETs

    SciTech Connect

    Limouny, L. Kaaouachi, A. El Tata, O.; Daoudi, E.; Errai, M.; Dlimi, S.; Idrissi, H. El; Zatni, A.

    2014-01-27

    We investigate the low temperature density dependent conductivity of two dimensional electron systems in zero magnetic field for sample Si-15 MOSFETs. The first purpose of this paper is to establish that the knee of the conductivity σ{sub 0} (σ{sub 0} is the T = 0.3 conductivity obtained by linear extrapolation of the curves of σ (T) for different values of electron density, n{sub s}) as a function of the carrier densities n{sub s} for T = 0.3 K, observed by Lai et al. and Limouny et al. in previous work for two different samples, is independent of temperature. The second aim is the determination of the critical density, n{sub c}, of the metal-insulator transition. Many methods are used in this investigation of n{sub c} which have been already used for other samples. The motivation behind this last study is the observation of many values of n{sub c} that have been obtained from different methods and that are slightly different. We will use in this study three methods with the intention to infer which one is more appropriate to obtain n{sub c}.

  14. A 2-D gel electrophoresis DNA image analysis algorithm with automatic thresholding

    NASA Astrophysics Data System (ADS)

    Kaabouch, Naima; Schultz, Richard R.

    2007-01-01

    Polymerase chain reaction (PCR) and gel electrophoresis are two widely used techniques for genetic studies that require the bench scientist to perform many tedious manual steps. Advances in automation are making these techniques more accessible, but detection and image analysis still remain labor-intensive. Although several commercial software packages are now available, DNA image analysis still requires some intervention by the user, and thus a certain level of image processing expertise. To allow researchers to speed up their analyses and obtain more repeatable results, we present a fully automated image analysis system for DNA or protein studies with high accuracy. The proposed system is based mainly on four steps: automatic thresholding, shifting, filtering, and processing. The automatic thresholding that is used to equalize the gray values of the gel electrophoreses image background is one of the key and novel operations in this algorithm. An enhancement is also used to improve poor quality images that have faint DNA bands. Experimental results show that the proposed method eliminates defects due to noise for good and average quality gel electrophoresis images, while it also improves the appearance of poor quality images.

  15. Performance improvements in temperature reconstructions of 2-D tunable diode laser absorption spectroscopy (TDLAS)

    NASA Astrophysics Data System (ADS)

    Choi, Doo-Won; Jeon, Min-Gyu; Cho, Gyeong-Rae; Kamimoto, Takahiro; Deguchi, Yoshihiro; Doh, Deog-Hee

    2016-02-01

    Performance improvement was attained in data reconstructions of 2-dimensional tunable diode laser absorption spectroscopy (TDLAS). Multiplicative Algebraic Reconstruction Technique (MART) algorithm was adopted for data reconstruction. The data obtained in an experiment for the measurement of temperature and concentration fields of gas flows were used. The measurement theory is based upon the Beer-Lambert law, and the measurement system consists of a tunable laser, collimators, detectors, and an analyzer. Methane was used as a fuel for combustion with air in the Bunsen-type burner. The data used for the reconstruction are from the optical signals of 8-laser beams passed on a cross-section of the methane flame. The performances of MART algorithm in data reconstruction were validated and compared with those obtained by Algebraic Reconstruction Technique (ART) algorithm.

  16. Enhanced 2D-image upconversion using solid-state lasers.

    PubMed

    Pedersen, Christian; Karamehmedović, Emir; Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter

    2009-11-01

    Based on enhanced upconversion, we demonstrate a highly efficient method for converting a full image from one part of the electromagnetic spectrum into a new desired wavelength region. By illuminating a metal transmission mask with a 765 nm Gaussian beam to create an image and subsequently focusing the image inside a nonlinear PPKTP crystal located in the high intra-cavity field of a 1342 nm solid-state Nd:YVO(4) laser, an upconverted image at 488 nm is generated. We have experimentally achieved an upconversion efficiency of 40% under CW conditions. The proposed technique can be further adapted for high efficiency mid-infrared image upconversion where direct and fast detection is difficult or impossible to perform with existing detector technologies. PMID:19997325

  17. Improving object detection in 2D images using a 3D world model

    NASA Astrophysics Data System (ADS)

    Viggh, Herbert E. M.; Cho, Peter L.; Armstrong-Crews, Nicholas; Nam, Myra; Shah, Danelle C.; Brown, Geoffrey E.

    2014-05-01

    A mobile robot operating in a netcentric environment can utilize offboard resources on the network to improve its local perception. One such offboard resource is a world model built and maintained by other sensor systems. In this paper we present results from research into improving the performance of Deformable Parts Model object detection algorithms by using an offboard 3D world model. Experiments were run for detecting both people and cars in 2D photographs taken in an urban environment. After generating candidate object detections, a 3D world model built from airborne Light Detection and Ranging (LIDAR) and aerial photographs was used to filter out false alarm using several types of geometric reasoning. Comparison of the baseline detection performance to the performance after false alarm filtering showed a significant decrease in false alarms for a given probability of detection.

  18. Dual layer electrode liquid crystal lens for 2D/3D tunable endoscopy imaging system.

    PubMed

    Hassanfiroozi, Amir; Huang, Yi-Pai; Javidi, Bahram; Shieh, Han-Ping D

    2016-04-18

    In this paper, we demonstrate a multi-functional liquid-crystal lens (MFLC-lens) based on dual-layer electrode design. Compared with the previous 3D endoscopes, which use double fixed lens capturing, the proposed LC lens is not only switchable between 2D and 3D modes, but also is able to adjust focus in both modes. The diameter of the MFLC-lens is only 1.42mm, which is much smaller than the available 3D endoscopes with double fixed lenses. To achieve the MFLC-lens, a high-resistance layer needs to be coated on the electrode to generate an ideal gradient electric-field distribution, which can induce a lens-like form of LC molecules. The parameters of high-resistive layer are investigated and discussed with an aim to optimize the performance of the MFLC-lens. PMID:27137290

  19. Terahertz wavefront assessment based on 2D electro-optic imaging

    NASA Astrophysics Data System (ADS)

    Cahyadi, Harsono; Ichikawa, Ryuji; Degert, Jérôme; Freysz, Eric; Yasui, Takeshi; Abraham, Emmanuel

    2015-03-01

    Complete characterization of terahertz (THz) radiation becomes an interesting yet challenging study for many years. In visible optical region, the wavefront assessment has been proved as a powerful tool for the beam profiling and characterization, which consequently requires 2-dimension (2D) single-shot acquisition of the beam cross-section to provide the spatial profile in time- and frequency-domain. In THz region, the main problem is the lack of effective THz cameras to satisfy this need. In this communication, we propose a simple setup based on free-space collinear 2D electrooptic sampling in a ZnTe crystal for the characterization of THz wavefronts. In principle, we map the optically converted, time-resolved data of the THz pulse by changing the time delay between the probe pulse and the generated THz pulse. The temporal waveforms from different lens-ZnTe distances can clearly indicate the evolution of THz beam as it is converged, focused, or diverged. From the Fourier transform of the temporal waveforms, we can obtain the spectral profile of a broadband THz wave, which in this case within the 0.1-2 THz range. The spectral profile also provides the frequency dependency of the THz pulse amplitude. The comparison between experimental and theoretical results at certain frequencies (here we choose 0.285 and 1.035 THz) is in a good agreement suggesting that our system is capable of THz wavefront characterization. Furthermore, the implementation of Hartmann/Shack-Hartmann sensor principle enables the reconstruction of THz wavefront. We demonstrate the reconstruction of THz wavefronts which are changed from planar wave to spherical one due to the insertion of convex THz lens in the THz beam path. We apply and compare two different reconstruction methods: linear integration and Zernike polynomial. Roughly we conclude that the Zernike method provide smoother wavefront shape that can be elaborated later into quantitative-qualitative analysis about the wavefront distortion.

  20. Assessing 3D tunnel position in ACL reconstruction using a novel single image 3D-2D registration

    NASA Astrophysics Data System (ADS)

    Kang, X.; Yau, W. P.; Otake, Y.; Cheung, P. Y. S.; Hu, Y.; Taylor, R. H.

    2012-02-01

    The routinely used procedure for evaluating tunnel positions following anterior cruciate ligament (ACL) reconstructions based on standard X-ray images is known to pose difficulties in terms of obtaining accurate measures, especially in providing three-dimensional tunnel positions. This is largely due to the variability in individual knee joint pose relative to X-ray plates. Accurate results were reported using postoperative CT. However, its extensive usage in clinical routine is hampered by its major requirement of having CT scans of individual patients, which is not available for most ACL reconstructions. These difficulties are addressed through the proposed method, which aligns a knee model to X-ray images using our novel single-image 3D-2D registration method and then estimates the 3D tunnel position. In the proposed method, the alignment is achieved by using a novel contour-based 3D-2D registration method wherein image contours are treated as a set of oriented points. However, instead of using some form of orientation weighting function and multiplying it with a distance function, we formulate the 3D-2D registration as a probability density estimation using a mixture of von Mises-Fisher-Gaussian (vMFG) distributions and solve it through an expectation maximization (EM) algorithm. Compared with the ground-truth established from postoperative CT, our registration method in an experiment using a plastic phantom showed accurate results with errors of (-0.43°+/-1.19°, 0.45°+/-2.17°, 0.23°+/-1.05°) and (0.03+/-0.55, -0.03+/-0.54, -2.73+/-1.64) mm. As for the entry point of the ACL tunnel, one of the key measurements, it was obtained with high accuracy of 0.53+/-0.30 mm distance errors.

  1. Known-component 3D-2D registration for image guidance and quality assurance in spine surgery pedicle screw placement

    NASA Astrophysics Data System (ADS)

    Uneri, A.; Stayman, J. W.; De Silva, T.; Wang, A. S.; Kleinszig, G.; Vogt, S.; Khanna, A. J.; Wolinsky, J.-P.; Gokaslan, Z. L.; Siewerdsen, J. H.

    2015-03-01

    Purpose. To extend the functionality of radiographic / fluoroscopic imaging systems already within standard spine surgery workflow to: 1) provide guidance of surgical device analogous to an external tracking system; and 2) provide intraoperative quality assurance (QA) of the surgical product. Methods. Using fast, robust 3D-2D registration in combination with 3D models of known components (surgical devices), the 3D pose determination was solved to relate known components to 2D projection images and 3D preoperative CT in near-real-time. Exact and parametric models of the components were used as input to the algorithm to evaluate the effects of model fidelity. The proposed algorithm employs the covariance matrix adaptation evolution strategy (CMA-ES) to maximize gradient correlation (GC) between measured projections and simulated forward projections of components. Geometric accuracy was evaluated in a spine phantom in terms of target registration error at the tool tip (TREx), and angular deviation (TREΦ) from planned trajectory. Results. Transpedicle surgical devices (probe tool and spine screws) were successfully guided with TREx<2 mm and TREΦ <0.5° given projection views separated by at least >30° (easily accommodated on a mobile C-arm). QA of the surgical product based on 3D-2D registration demonstrated the detection of pedicle screw breach with TREx<1 mm, demonstrating a trend of improved accuracy correlated to the fidelity of the component model employed. Conclusions. 3D-2D registration combined with 3D models of known surgical components provides a novel method for near-real-time guidance and quality assurance using a mobile C-arm without external trackers or fiducial markers. Ongoing work includes determination of optimal views based on component shape and trajectory, improved robustness to anatomical deformation, and expanded preclinical testing in spine and intracranial surgeries.

  2. 2D-PAGE protein analysis of dinoflagellate Alexandrium minutum based on three different temperatures

    NASA Astrophysics Data System (ADS)

    Latib, Norhidayu Abdul; Norshaha, Safida Anira; Usup, Gires; Yusof, Nurul Yuziana Mohd

    2015-09-01

    Harmful algae bloom or red tide seems to be considered as threat to ecosystem, especially to human consumption because of the production of neurotoxin by dinoflagellates species such as Alexandrium minutum which can lead to paralytic shellfish poisoning. The aim of this study is to determine the most suitable method for protein extraction of A. minutum followed by determination of differential protein expression of A. minutum on three different temperatures (15°C, 26°C and 31.5°C). After the optimization, the protein extract was subjected to two-dimensional polyacrylamide gel electrophoresis (2-DE) to compare the intensity and distribution of the protein spots. Based on quantitative and qualitative protein assessment, use of Trizol reagent is the most suitable method to extract protein from A. minutum. 2-DE analysis of the samples results in different distribution and intensity of the protein spots were compared between 15°C, 26°C and 31.5°C.

  3. A 2D multiresolution image reconstruction method in X-ray computed tomography.

    PubMed

    Costin, Marius; Lazaro-Ponthus, Delphine; Legoupil, Samuel; Duvauchelle, Philippe; Kaftandjian, Valérie

    2011-01-01

    We propose a multiresolution X-ray imaging method designed for non-destructive testing/evaluation (NDT/NDE) applications which can also be used for small animal imaging studies. Two sets of projections taken at different magnifications are combined and a multiresolution image is reconstructed. A geometrical relation is introduced in order to combine properly the two sets of data and the processing using wavelet transforms is described. The accuracy of the reconstruction procedure is verified through a comparison to the standard filtered backprojection (FBP) algorithm on simulated data. PMID:21606585

  4. Preparation of 2D sequences of corneal images for 3D model building.

    PubMed

    Elbita, Abdulhakim; Qahwaji, Rami; Ipson, Stanley; Sharif, Mhd Saeed; Ghanchi, Faruque

    2014-04-01

    A confocal microscope provides a sequence of images, at incremental depths, of the various corneal layers and structures. From these, medical practioners can extract clinical information on the state of health of the patient's cornea. In this work we are addressing problems associated with capturing and processing these images including blurring, non-uniform illumination and noise, as well as the displacement of images laterally and in the anterior-posterior direction caused by subject movement. The latter may cause some of the captured images to be out of sequence in terms of depth. In this paper we introduce automated algorithms for classification, reordering, registration and segmentation to solve these problems. The successful implementation of these algorithms could open the door for another interesting development, which is the 3D modelling of these sequences. PMID:24612710

  5. Fuzzy watershed segmentation algorithm: an enhanced algorithm for 2D gel electrophoresis image segmentation.

    PubMed

    Rashwan, Shaheera; Sarhan, Amany; Faheem, Muhamed Talaat; Youssef, Bayumy A

    2015-01-01

    Detection and quantification of protein spots is an important issue in the analysis of two-dimensional electrophoresis images. However, there is a main challenge in the segmentation of 2DGE images which is to separate overlapping protein spots correctly and to find the weak protein spots. In this paper, we describe a new robust technique to segment and model the different spots present in the gels. The watershed segmentation algorithm is modified to handle the problem of over-segmentation by initially partitioning the image to mosaic regions using the composition of fuzzy relations. The experimental results showed the effectiveness of the proposed algorithm to overcome the over segmentation problem associated with the available algorithm. We also use a wavelet denoising function to enhance the quality of the segmented image. The results of using a denoising function before the proposed fuzzy watershed segmentation algorithm is promising as they are better than those without denoising. PMID:26510287

  6. Registration of 2D to 3D joint images using phase-based mutual information

    NASA Astrophysics Data System (ADS)

    Dalvi, Rupin; Abugharbieh, Rafeef; Pickering, Mark; Scarvell, Jennie; Smith, Paul

    2007-03-01

    Registration of two dimensional to three dimensional orthopaedic medical image data has important applications particularly in the area of image guided surgery and sports medicine. Fluoroscopy to computer tomography (CT) registration is an important case, wherein digitally reconstructed radiographs derived from the CT data are registered to the fluoroscopy data. Traditional registration metrics such as intensity-based mutual information (MI) typically work well but often suffer from gross misregistration errors when the image to be registered contains a partial view of the anatomy visible in the target image. Phase-based MI provides a robust alternative similarity measure which, in addition to possessing the general robustness and noise immunity that MI provides, also employs local phase information in the registration process which makes it less susceptible to the aforementioned errors. In this paper, we propose using the complex wavelet transform for computing image phase information and incorporating that into a phase-based MI measure for image registration. Tests on a CT volume and 6 fluoroscopy images of the knee are presented. The femur and the tibia in the CT volume were individually registered to the fluoroscopy images using intensity-based MI, gradient-based MI and phase-based MI. Errors in the coordinates of fiducials present in the bone structures were used to assess the accuracy of the different registration schemes. Quantitative results demonstrate that the performance of intensity-based MI was the worst. Gradient-based MI performed slightly better, while phase-based MI results were the best consistently producing the lowest errors.

  7. Applying a 2D based CAD scheme for detecting micro-calcification clusters using digital breast tomosynthesis images: an assessment

    NASA Astrophysics Data System (ADS)

    Park, Sang Cheol; Zheng, Bin; Wang, Xiao-Hui; Gur, David

    2008-03-01

    Digital breast tomosynthesis (DBT) has emerged as a promising imaging modality for screening mammography. However, visually detecting micro-calcification clusters depicted on DBT images is a difficult task. Computer-aided detection (CAD) schemes for detecting micro-calcification clusters depicted on mammograms can achieve high performance and the use of CAD results can assist radiologists in detecting subtle micro-calcification clusters. In this study, we compared the performance of an available 2D based CAD scheme with one that includes a new grouping and scoring method when applied to both projection and reconstructed DBT images. We selected a dataset involving 96 DBT examinations acquired on 45 women. Each DBT image set included 11 low dose projection images and a varying number of reconstructed image slices ranging from 18 to 87. In this dataset 20 true-positive micro-calcification clusters were visually detected on the projection images and 40 were visually detected on the reconstructed images, respectively. We first applied the CAD scheme that was previously developed in our laboratory to the DBT dataset. We then tested a new grouping method that defines an independent cluster by grouping the same cluster detected on different projection or reconstructed images. We then compared four scoring methods to assess the CAD performance. The maximum sensitivity level observed for the different grouping and scoring methods were 70% and 88% for the projection and reconstructed images with a maximum false-positive rate of 4.0 and 15.9 per examination, respectively. This preliminary study demonstrates that (1) among the maximum, the minimum or the average CAD generated scores, using the maximum score of the grouped cluster regions achieved the highest performance level, (2) the histogram based scoring method is reasonably effective in reducing false-positive detections on the projection images but the overall CAD sensitivity is lower due to lower signal-to-noise ratio, and (3) CAD achieved higher sensitivity and higher false-positive rate (per examination) on the reconstructed images. We concluded that without changing the detection threshold or performing pre-filtering to possibly increase detection sensitivity, current CAD schemes developed and optimized for 2D mammograms perform relatively poorly and need to be re-optimized using DBT datasets and new grouping and scoring methods need to be incorporated into the schemes if these are to be used on the DBT examinations.

  8. Automatic Characterization of the Physiological Condition of the Carotid Artery in 2D Ultrasound Image Sequences Using Spatiotemporal and Spatiospectral 2D Maps

    PubMed Central

    Hamid Muhammed, Hamed; Azar, Jimmy C.

    2014-01-01

    A novel method for characterizing and visualizing the progression of waves along the walls of the carotid artery is presented. The new approach is noninvasive and able to simultaneously capture the spatial and the temporal propagation of wavy patterns along the walls of the carotid artery in a completely automated manner. Spatiotemporal and spatiospectral 2D maps describing these patterns (in both the spatial and the frequency domains, resp.) were generated and analyzed by visual inspection as well as automatic feature extraction and classification. Three categories of cases were considered: pathological elderly, healthy elderly, and healthy young cases. Automatic differentiation, between cases of these three categories, was achieved with a sensitivity of 97.1% and a specificity of 74.5%. Two features were proposed and computed to measure the homogeneity of the spatiospectral 2D map which presents the spectral characteristics of the carotid artery wall's wavy motion pattern which are related to the physical, mechanical (e.g., elasticity), and physiological properties and conditions along the artery. These results are promising and confirm the potential of the proposed method in providing useful information which can help in revealing the physiological condition of the cardiovascular system. PMID:24971088

  9. Tracking contrast agents using real-time 2D photoacoustic imaging system for cardiac applications

    NASA Astrophysics Data System (ADS)

    Olafsson, Ragnar; Montilla, Leonardo; Ingram, Pier; Witte, Russell S.

    2009-02-01

    Photoacoustic (PA) imaging is a rapidly developing imaging modality that can detect optical contrast agents with high sensitivity. While detectors in PA imaging have traditionally been single element ultrasound transducers, use of array systems is desirable because they potentially provide high frame rates to capture dynamic events, such as injection and distribution of contrast in clinical applications. We present preliminary data consisting of 40 second sequences of coregistered pulse-echo (PE) and PA images acquired simultaneously in real time using a clinical ultrasonic machine. Using a 7 MHz linear array, the scanner allowed simultaneous acquisition of inphase-quadrature (IQ) data on 64 elements at a rate limited by the illumination source (Q-switched laser at 20 Hz) with spatial resolution determined to be 0.6 mm (axial) and 0.4 mm (lateral). PA images had a signal-to-noise ratio of approximately 35 dB without averaging. The sequences captured the injection and distribution of an infrared-absorbing contrast agent into a cadaver rat heart. From these data, a perfusion time constant of 0.23 s-1 was estimated. After further refinement, the system will be tested in live animals. Ultimately, an integrated system in the clinic could facilitate inexpensive molecular screening for coronary artery disease.

  10. Optoacoustic temperature monitoring during HIFU impact on biological tissues: ex vivo study and numerical simulations of 2D temperature reconstruction

    NASA Astrophysics Data System (ADS)

    Nikitin, Sergey; Khokhlova, Tatiana; Pelivanov, Ivan

    2012-02-01

    Dependencies of the optoacoustic (OA) transformation efficiency on tissue temperature were obtained for the application in OA temperature monitoring during thermal therapies. Accurate measurement of the OA signal amplitude versus temperature was performed in different ex-vivo tissues in the temperature range 25°C - 80°C. The investigated tissues were selected to represent different structural components: chicken breast (skeletal muscle), porcine lard (fatty tissue) and porcine liver (richly perfused tissue). Backward mode of the OA signal detection and a narrow probe laser beam were used in the experiments to avoid the influence of changes in light scattering with tissue coagulation on the OA signal amplitude. Measurements were performed in heating and cooling regimes. Characteristic behavior of the OA signal amplitude temperature dependences in different temperature ranges were described in terms of changes in different structural components of the tissue samples. Finally, numerical simulation of the OA temperature monitoring with a linear transducers array was performed to demonstrate the possibility of real-time temperature mapping.

  11. Magnetic resonance image reconstruction using trained geometric directions in 2D redundant wavelets domain and non-convex optimization.

    PubMed

    Ning, Bende; Qu, Xiaobo; Guo, Di; Hu, Changwei; Chen, Zhong

    2013-11-01

    Reducing scanning time is significantly important for MRI. Compressed sensing has shown promising results by undersampling the k-space data to speed up imaging. Sparsity of an image plays an important role in compressed sensing MRI to reduce the image artifacts. Recently, the method of patch-based directional wavelets (PBDW) which trains geometric directions from undersampled data has been proposed. It has better performance in preserving image edges than conventional sparsifying transforms. However, obvious artifacts are presented in the smooth region when the data are highly undersampled. In addition, the original PBDW-based method does not hold obvious improvement for radial and fully 2D random sampling patterns. In this paper, the PBDW-based MRI reconstruction is improved from two aspects: 1) An efficient non-convex minimization algorithm is modified to enhance image quality; 2) PBDW are extended into shift-invariant discrete wavelet domain to enhance the ability of transform on sparsifying piecewise smooth image features. Numerical simulation results on vivo magnetic resonance images demonstrate that the proposed method outperforms the original PBDW in terms of removing artifacts and preserving edges. PMID:23992629

  12. 2D and 3D Refraction Based X-ray Imaging Suitable for Clinical and Pathological Diagnosis

    SciTech Connect

    Ando, Masami; Bando, Hiroko; Ueno, Ei

    2007-01-19

    The first observation of micro papillary (MP) breast cancer by x-ray dark-field imaging (XDFI) and the first observation of the 3D x-ray internal structure of another breast cancer, ductal carcinoma in-situ (DCIS), are reported. The specimen size for the sheet-shaped MP was 26 mm x 22 mm x 2.8 mm, and that for the rod-shaped DCIS was 3.6 mm in diameter and 4.7 mm in height. The experiment was performed at the Photon Factory, KEK: High Energy Accelerator Research Organization. We achieved a high-contrast x-ray image by adopting a thickness-controlled transmission-type angular analyzer that allows only refraction components from the object for 2D imaging. This provides a high-contrast image of cancer-cell nests, cancer cells and stroma. For x-ray 3D imaging, a new algorithm due to the refraction for x-ray CT was created. The angular information was acquired by x-ray optics diffraction-enhanced imaging (DEI). The number of data was 900 for each reconstruction. A reconstructed CT image may include ductus lactiferi, micro calcification and the breast gland. This modality has the possibility to open up a new clinical and pathological diagnosis using x-ray, offering more precise inspection and detection of early signs of breast cancer.

  13. High resolution human diffusion tensor imaging using 2-D navigated multi-shot SENSE EPI at 7 Tesla

    PubMed Central

    Jeong, Ha-Kyu; Gore, John C.; Anderson, Adam W.

    2012-01-01

    The combination of parallel imaging with partial Fourier acquisition has greatly improved the performance of diffusion-weighted single-shot EPI and is the preferred method for acquisitions at low to medium magnetic field strength such as 1.5 or 3 Tesla. Increased off-resonance effects and reduced transverse relaxation times at 7 Tesla, however, generate more significant artifacts than at lower magnetic field strength and limit data acquisition. Additional acceleration of k-space traversal using a multi-shot approach, which acquires a subset of k-space data after each excitation, reduces these artifacts relative to conventional single-shot acquisitions. However, corrections for motion-induced phase errors are not straightforward in accelerated, diffusion-weighted multi-shot EPI because of phase aliasing. In this study, we introduce a simple acquisition and corresponding reconstruction method for diffusion-weighted multi-shot EPI with parallel imaging suitable for use at high field. The reconstruction uses a simple modification of the standard SENSE algorithm to account for shot-to-shot phase errors; the method is called Image Reconstruction using Image-space Sampling functions (IRIS). Using this approach, reconstruction from highly aliased in vivo image data using 2-D navigator phase information is demonstrated for human diffusion-weighted imaging studies at 7 Tesla. The final reconstructed images show submillimeter in-plane resolution with no ghosts and much reduced blurring and off-resonance artifacts. PMID:22592941

  14. New Insights to the Sawtooth Oscillation (m/n=1/1 mode) in Hot Plasmas based on High Resolution 2-D Images of Te Fluctuations

    SciTech Connect

    H.K. Park, N.C. Luhmann, Jr, A.J.H. Donn, C.W. Domier, T. Munsat, M.J. Van de Pol, and the TEXTOR Team

    2007-11-26

    Two dimensional (2-D) images of electron temperature fluctuations with high temporal and spatial resolution have been employed to study the sawtooth oscillation (m/n=1/1 mode) in Toroidal EXperiment for Technology Oriented Research (TEXTOR) tokamak plasmas. 2-D imaging data revealed new physics which were not available in previous studies based on the 1-D electron temperature measurement and X-ray tomography. Review of the physics of the sawtooth oscillation is given by comparative studies with prominent theoretical models suggest that a new physics paradigm is needed to describe the reconnection physics of the sawtooth oscillation. The new insights are: A pressure driven instability (not a ballooning mode) leads to the X-point reconnection process. The reconnection process is identified as a random 3-D local reconnection process with a helical structure. The reconnection time scale is similar for different types of sawtooth oscillation ("kink" and tearing type) and is significantly faster than the resistive time scale. Heat flow from the core to the outside of the inversion radius during the reconnection process is highly collective rather than stochastic.

  15. Prostate boundary segmentation from ultrasound images using 2D active shape models: optimisation and extension to 3D.

    PubMed

    Hodge, Adam C; Fenster, Aaron; Downey, Dónal B; Ladak, Hanif M

    2006-12-01

    Boundary outlining, or segmentation, of the prostate is an important task in diagnosis and treatment planning for prostate cancer. This paper describes an algorithm based on two-dimensional (2D) active shape models (ASM) for semi-automatic segmentation of the prostate boundary from ultrasound images. Optimisation of the 2D ASM for prostatic ultrasound was done first by examining ASM construction and image search parameters. Extension of the algorithm to three-dimensional (3D) segmentation was then done using rotational-based slicing. Evaluation of the 3D segmentation algorithm used distance- and volume-based error metrics to compare algorithm generated boundary outlines to gold standard (manually generated) boundary outlines. Minimum description length landmark placement for ASM construction, and specific values for constraints and image search were found to be optimal. Evaluation of the algorithm versus gold standard boundaries found an average mean absolute distance of 1.09+/-0.49 mm, an average percent absolute volume difference of 3.28+/-3.16%, and a 5x speed increase versus manual segmentation. PMID:16930764

  16. Biomechanical properties and microarchitecture parameters of trabecular bone are correlated with stochastic measures of 2D projection images

    PubMed Central

    Dong, Xuanliang N.; Shirvaikar, Mukul; Wang, Xiaodu

    2013-01-01

    It is well known that loss of bone mass, quantified by areal bone mineral density (aBMD) using DXA, is associated with the increasing risk of bone fractures. However, bone mineral density alone cannot fully explain changes in fracture risks. On top of bone mass, bone architecture has been identified as another key contributor to fracture risk. In this study, we used a novel stochastic approach to assess the distribution of aBMD from 2D projection images of Micro-CT scans of trabecular bone specimens at a resolution comparable to DXA images. Sill variance, a stochastic measure of distribution of aBMD, had significant relationships with microarchitecture parameters of trabecular bone, including bone volume fraction, bone surface-to-volume ratio, trabecular thickness, trabecular number, trabecular separation and anisotropy. Accordingly, it showed significantly positive correlations with strength and elastic modulus of trabecular bone. Moreover, a combination of aBMD and sill variance derived from the 2D projection images (R2=0.85) predicted bone strength better than using aBMD alone (R2=0.63). Thus, it would be promising to extend the stochastic approach to routine DXA scans to assess the distribution of aBMD, offering a more clinically significant technique for predicting risks of bone fragility fractures. PMID:23756232

  17. Machine Learning of Hierarchical Clustering to Segment 2D and 3D Images

    PubMed Central

    Nunez-Iglesias, Juan; Kennedy, Ryan; Parag, Toufiq; Shi, Jianbo; Chklovskii, Dmitri B.

    2013-01-01

    We aim to improve segmentation through the use of machine learning tools during region agglomeration. We propose an active learning approach for performing hierarchical agglomerative segmentation from superpixels. Our method combines multiple features at all scales of the agglomerative process, works for data with an arbitrary number of dimensions, and scales to very large datasets. We advocate the use of variation of information to measure segmentation accuracy, particularly in 3D electron microscopy (EM) images of neural tissue, and using this metric demonstrate an improvement over competing algorithms in EM and natural images. PMID:23977123

  18. Convertible 2D-3D display using an edge-lit light guide plate based on integral imaging

    NASA Astrophysics Data System (ADS)

    Wang, Zi; Wang, Anting; Wang, Shulu; Ma, Xiaohui; Deng, Zhengbiao; Ming, Hai

    2015-09-01

    A thin and lensless two-dimensional (2D) to three-dimensional (3D) convertible display based on integral imaging using an edge-lit light guide plate (LGP) is proposed with improved optical efficiency. The proposed system is composed of a general flat backlight and an edge-lit LGP which is commonly used in the backlight of LCD and a LC panel. The edge lit LGP is a waveguide (an acrylic sheet) that is drilled by laser to form a diffuser dot array at the bottom and edge illuminated with LEDs. Light from the LEDs is channeled through the waveguide to the opposite side except where it encounters the diffuser dots, which scatter light and cause bright spots to appear. A point light source array for 3D mode is created then. A general flat backlight behind the transparent LGP is turned on for 2D mode meanwhile edge-lit light is turned off. The 2D and the 3D display modes can be simply modulated by turning on different light source. The explanation of the proposed system is provided and the experimental results are also presented.

  19. The distribution of D2/D3 receptor binding in the adolescent rhesus monkey using small animal PET imaging

    PubMed Central

    Christian, BT; Vandehey, NT; Fox, AS; Murali, D; Oakes, TR; Converse, AK; Nickles, RJ; Shelton, SE; Davidson, RJ; Kalin, NH

    2009-01-01

    PET imaging of the neuroreceptor systems in the brain has earned a prominent role in studying normal development, neuropsychiatric illness and developing targeted drugs. The dopaminergic system is of particular interest due to its role in the development of cognitive function and mood as well as its suspected involvement in neuropsychiatric illness. Nonhuman primate animal models provide a valuable resource for relating neurochemical changes to behavior. To facilitate comparison within and between primate models, we report in vivo D2/D3 binding in a large cohort of adolescent rhesus monkeys. Methods In this work, the in vivo D2/D3 dopamine receptor availability was measured in a cohort of 33 rhesus monkeys in the adolescent stage of development (3.2 – 5.3 years). Both striatal and extrastriatal D2/D3 binding were measured using [F-18]fallypride with a high resolution small animal PET scanner. The distribution volume ratio (DVR) was measured for all subjects and group comparisons of D2/D3 binding among the cohort were made based on age and sex. Because two sequential studies were acquired from a single [F-18]fallypride batch, the effect of competing (unlabeled) ligand mass was also investigated. Results Among this cohort, the rank order of regional D2/D3 receptor binding did not vary from previous studies with adult rhesus monkeys, with: putamen > caudate > ventral striatum > amygdala ~ substantia nigra > medial dorsal thalamus > lateral temporal cortex ~ frontal cortex. The DVR coefficient of variation ranged from 14% – 26%, with the greatest variance seen in the head of the caudate. There were significant sex differences in [F-18]fallypride kinetics in the pituitary gland, but this was not observed for regions within the blood-brain barrier. Furthermore, no regions in the brain showed significant sex or age related differences in DVR within this small age range. Based on a wide range of injected fallypride mass across the cohort, significant competition effects could only be detected in the substantia nigra, thalamus, and frontal cortex, and were not evident above intersubject variability in all other regions. Conclusion These data represent the first report of large cohort in vivo D2/D3 dopamine whole brain binding in the adolescent brain and will serve as a valuable comparison for understanding dopamine changes during this critical time of development and provide a framework for creating a dopaminergic biochemical atlas for the rhesus monkey. PMID:19015034

  20. Designing and construction of a prototype of (GEM) detector for 2D medical imaging application

    NASA Astrophysics Data System (ADS)

    Alghamdi, Abdulrahman S.; Alanazi, Mohammed S.; Aldosary, Abdullah F.; Maghrabi, A. H.

    2015-03-01

    Due to the limited resolution and accuracy of several technologies that are able to get a digital X-ray image with a good performance in the very high rates, micro-pattern technology can achieve these features by using the most effective example of which is gas electron multiplier (GEM). The main objective of this project is to develop a two dimensions imaging that can be used in medical imaging purposes. The project consists of the theoretical parts of the process, including simulating the best detector dimensions, geometry, and the energy range of the applied radiation. Furthermore, constructing a large active area of triple GEM detector, and preparing the necessary setup parts for medical imaging system assumed. This paper presents the designing and construction of a prototype of triple-GEM detector (10cm x10 cm) that can achieve the goals as a first step toward attaining this project. In addition, the preliminary results from X-ray and some gamma sources as a testing of the prototype detector will be presented, added to that the discussions of outlined tasks and achievements. This paper will show the future plane of the whole project and more details about the next stages.

  1. Learning-based roof style classification in 2D satellite images

    NASA Astrophysics Data System (ADS)

    Zang, Andi; Zhang, Xi; Chen, Xin; Agam, Gady

    2015-05-01

    Accurately recognizing building roof style leads to a much more realistic 3D building modeling and rendering. In this paper, we propose a novel system for image based roof style classification using machine learning technique. Our system is capable of accurately recognizing four individual roof styles and a complex roof which is composed of multiple parts. We make several novel contributions in this paper. First, we propose an algorithm that segments a complex roof to parts which enable our system to recognize the entire roof based on recognition of each part. Second, to better characterize a roof image, we design a new feature extracted from a roof edge image. We demonstrate that this feature has much better performance compared to recognition results generated by Histogram of Oriented Gradient (HOG), Scale-invariant Feature Transform (SIFT) and Local Binary Patterns (LBP). Finally, to generate a classifier, we propose a learning scheme that trains the classifier using both synthetic and real roof images. Experiment results show that our classifier performs well on several test collections.

  2. A GPU Simulation Tool for Training and Optimisation in 2D Digital X-Ray Imaging

    PubMed Central

    Gallio, Elena; Rampado, Osvaldo; Gianaria, Elena; Bianchi, Silvio Diego; Ropolo, Roberto

    2015-01-01

    Conventional radiology is performed by means of digital detectors, with various types of technology and different performance in terms of efficiency and image quality. Following the arrival of a new digital detector in a radiology department, all the staff involved should adapt the procedure parameters to the properties of the detector, in order to achieve an optimal result in terms of correct diagnostic information and minimum radiation risks for the patient. The aim of this study was to develop and validate a software capable of simulating a digital X-ray imaging system, using graphics processing unit computing. All radiological image components were implemented in this application: an X-ray tube with primary beam, a virtual patient, noise, scatter radiation, a grid and a digital detector. Three different digital detectors (two digital radiography and a computed radiography systems) were implemented. In order to validate the software, we carried out a quantitative comparison of geometrical and anthropomorphic phantom simulated images with those acquired. In terms of average pixel values, the maximum differences were below 15%, while the noise values were in agreement with a maximum difference of 20%. The relative trends of contrast to noise ratio versus beam energy and intensity were well simulated. Total calculation times were below 3 seconds for clinical images with pixel size of actual dimensions less than 0.2 mm. The application proved to be efficient and realistic. Short calculation times and the accuracy of the results obtained make this software a useful tool for training operators and dose optimisation studies. PMID:26545097

  3. A GPU Simulation Tool for Training and Optimisation in 2D Digital X-Ray Imaging.

    PubMed

    Gallio, Elena; Rampado, Osvaldo; Gianaria, Elena; Bianchi, Silvio Diego; Ropolo, Roberto

    2015-01-01

    Conventional radiology is performed by means of digital detectors, with various types of technology and different performance in terms of efficiency and image quality. Following the arrival of a new digital detector in a radiology department, all the staff involved should adapt the procedure parameters to the properties of the detector, in order to achieve an optimal result in terms of correct diagnostic information and minimum radiation risks for the patient. The aim of this study was to develop and validate a software capable of simulating a digital X-ray imaging system, using graphics processing unit computing. All radiological image components were implemented in this application: an X-ray tube with primary beam, a virtual patient, noise, scatter radiation, a grid and a digital detector. Three different digital detectors (two digital radiography and a computed radiography systems) were implemented. In order to validate the software, we carried out a quantitative comparison of geometrical and anthropomorphic phantom simulated images with those acquired. In terms of average pixel values, the maximum differences were below 15%, while the noise values were in agreement with a maximum difference of 20%. The relative trends of contrast to noise ratio versus beam energy and intensity were well simulated. Total calculation times were below 3 seconds for clinical images with pixel size of actual dimensions less than 0.2 mm. The application proved to be efficient and realistic. Short calculation times and the accuracy of the results obtained make this software a useful tool for training operators and dose optimisation studies. PMID:26545097

  4. Application and further development of diffusion based 2D chemical imaging techniques in the rhizosphere

    NASA Astrophysics Data System (ADS)

    Hoefer, Christoph; Santner, Jakob; Borisov, Sergey; Kreuzeder, Andreas; Wenzel, Walter; Puschenreiter, Markus

    2015-04-01

    Two dimensional chemical imaging of root processes refers to novel in situ methods to investigate and map solutes at a high spatial resolution (sub-mm). The visualization of these solutes reveals new insights in soil biogeochemistry and root processes. We derive chemical images by using data from DGT-LA-ICP-MS (Diffusive Gradients in Thin Films and Laser Ablation Inductively Coupled Plasma Mass Spectrometry) and POS (Planar Optode Sensors). Both technologies have shown promising results when applied in aqueous environment but need to be refined and improved for imaging at the soil-plant interface. Co-localized mapping using combined DGT and POS technologies and the development of new gel combinations are in our focus. DGTs are smart and thin (<0.4 mm) hydrogels; containing a binding resin for the targeted analytes (e.g. trace metals, phosphate, sulphide or radionuclides). The measurement principle is passive and diffusion based. The present analytes are diffusing into the gel and are bound by the resin. Thereby, the resin acts as zero sink. After application, DGTs are retrieved, dried, and analysed using LA-ICP-MS. The data is then normalized by an internal standard (e.g. 13C), calibrated using in-house standards and chemical images of the target area are plotted using imaging software. POS are, similar to DGT, thin sensor foils containing a fluorophore coating depending on the target analyte. The measurement principle is based on excitation of the flourophore by a specific wavelength and emission of the fluorophore depending on the presence of the analyte. The emitted signal is captured using optical filters and a DSLR camera. While DGT analysis is destructive, POS measurements can be performed continuously during the application. Both semi-quantitative techniques allow an in situ application to visualize chemical processes directly at the soil-plant interface. Here, we present a summary of results from rhizotron experiments with different plants in metal contaminated and agricultural soils.

  5. 2D and 3D PIC-MCC simulations of a low temperature magnetized plasma on CPU and GPU

    NASA Astrophysics Data System (ADS)

    Claustre, Jonathan; Chaudhury, Bhaskar; Fubiani, Gwenael; Boeuf, Jean-Pierre

    2012-10-01

    A Particle-In-Cell Monte Carlo Collisions model is used to described plasma transport in a low temperature magnetized plasma under conditions similar to those of the negative ion source for the neutral beam injector of ITER. A large diamagnetic electron current is present in the plasma because of the electron pressure gradient between the ICP driver of the source and the entrance of the magnetic filter, and is directed toward the chamber walls. The plasma potential adjusts to limit the diamagnetic electron current to the wall, leading to large electron current flow through the filter, and to a non uniform plasma density in the region between magnetic filter and extracting grids. On the basis of the PIC-MCC simulation results, we describe the plasma properties and electron current density distributions through the filter in 2D and 3D situations and use these models to better understand plasma transport across the filter in these conditions. We also present comparisons between computation times of two PIC-MCC simulation codes that have been developed for operations on standard CPU (Central Processing Units, code in Fortran) and on GPU (Graphics Processing Units, code in CUDA). The results show that the GPU simulation is about 25 times faster than the CPU one for a 2D domain with 512x512 grid points. The computation time ratio increases with the number of grid points.

  6. Security of Color Image Data Designed by Public-Key Cryptosystem Associated with 2D-DWT

    NASA Astrophysics Data System (ADS)

    Mishra, D. C.; Sharma, R. K.; Kumar, Manish; Kumar, Kuldeep

    2014-08-01

    In present times the security of image data is a major issue. So, we have proposed a novel technique for security of color image data by public-key cryptosystem or asymmetric cryptosystem. In this technique, we have developed security of color image data using RSA (Rivest-Shamir-Adleman) cryptosystem with two-dimensional discrete wavelet transform (2D-DWT). Earlier proposed schemes for security of color images designed on the basis of keys, but this approach provides security of color images with the help of keys and correct arrangement of RSA parameters. If the attacker knows about exact keys, but has no information of exact arrangement of RSA parameters, then the original information cannot be recovered from the encrypted data. Computer simulation based on standard example is critically examining the behavior of the proposed technique. Security analysis and a detailed comparison between earlier developed schemes for security of color images and proposed technique are also mentioned for the robustness of the cryptosystem.

  7. Single grating method for low dose 1-D and 2-D phase contrast X-ray imaging

    NASA Astrophysics Data System (ADS)

    Krejci, F.; Jakubek, J.; Kroupa, M.

    2011-01-01

    X-ray phase contrast imaging (XPCI) using a single absorption grating and a hybrid semiconductor pixel detector is a newly introduced approach with great potential for application in medicine, biology and material research. In comparison with a conventional grating interferometer technique, which requires a multiple-exposure (phase-stepping) procedure, our method is greatly simplified, because both phase gradient and absorption images are obtained from just one exposure. Consequently, the approach can significantly reduce the time-consuming scanning and also possibly the unnecessary dose. Examples of application of the single-grating approach as an imaging tool for investigations in biology are presented. Particularly, we present the extension of our 1-D single grating method to a two-direction sensitive technique. The novel 2-D sensitive XPCI method is based on precise sub-pixel position determination of the X-ray pattern projected by the two-dimensional transmission grating directly from the pattern image. In a single exposure, phase gradient images in two perpendicular directions together with the conventional attenuation image are produced. Results of the proof-of-concept experiment are presented.

  8. A general framework for face reconstruction using single still image based on 2D-to-3D transformation kernel.

    PubMed

    Fooprateepsiri, Rerkchai; Kurutach, Werasak

    2014-03-01

    Face authentication is a biometric classification method that verifies the identity of a user based on image of their face. Accuracy of the authentication is reduced when the pose, illumination and expression of the training face images are different than the testing image. The methods in this paper are designed to improve the accuracy of a features-based face recognition system when the pose between the input images and training images are different. First, an efficient 2D-to-3D integrated face reconstruction approach is introduced to reconstruct a personalized 3D face model from a single frontal face image with neutral expression and normal illumination. Second, realistic virtual faces with different poses are synthesized based on the personalized 3D face to characterize the face subspace. Finally, face recognition is conducted based on these representative virtual faces. Compared with other related works, this framework has the following advantages: (1) only one single frontal face is required for face recognition, which avoids the burdensome enrollment work; and (2) the synthesized face samples provide the capability to conduct recognition under difficult conditions like complex pose, illumination and expression. From the experimental results, we conclude that the proposed method improves the accuracy of face recognition by varying the pose, illumination and expression. PMID:24529782

  9. Label free biochemical 2D and 3D imaging using secondary ion mass spectrometry.

    PubMed

    Fletcher, John S; Vickerman, John C; Winograd, Nicholas

    2011-10-01

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) provides a method for the detection of native and exogenous compounds in biological samples on a cellular scale. Through the development of novel ion beams the amount of molecular signal available from the sample surface has been increased. Through the introduction of polyatomic ion beams, particularly C(60), ToF-SIMS can now be used to monitor molecular signals as a function of depth as the sample is eroded thus proving the ability to generate 3D molecular images. Here we describe how this new capability has led to the development of novel instrumentation for 3D molecular imaging while also highlighting the importance of sample preparation and discuss the challenges that still need to be overcome to maximise the impact of the technique. PMID:21664172

  10. Distributed Computing Architecture for Image-Based Wavefront Sensing and 2 D FFTs

    NASA Technical Reports Server (NTRS)

    Smith, Jeffrey S.; Dean, Bruce H.; Haghani, Shadan

    2006-01-01

    Image-based wavefront sensing (WFS) provides significant advantages over interferometric-based wavefi-ont sensors such as optical design simplicity and stability. However, the image-based approach is computational intensive, and therefore, specialized high-performance computing architectures are required in applications utilizing the image-based approach. The development and testing of these high-performance computing architectures are essential to such missions as James Webb Space Telescope (JWST), Terrestial Planet Finder-Coronagraph (TPF-C and CorSpec), and Spherical Primary Optical Telescope (SPOT). The development of these specialized computing architectures require numerous two-dimensional Fourier Transforms, which necessitate an all-to-all communication when applied on a distributed computational architecture. Several solutions for distributed computing are presented with an emphasis on a 64 Node cluster of DSPs, multiple DSP FPGAs, and an application of low-diameter graph theory. Timing results and performance analysis will be presented. The solutions offered could be applied to other all-to-all communication and scientifically computationally complex problems.

  11. 2D and 3D GPR imaging of structural ceilings in historic and existing constructions

    NASA Astrophysics Data System (ADS)

    Colla, Camilla

    2014-05-01

    GPR applications in civil engineering are to date quite diversified. With respect to civil constructions and monumental buildings, detection of voids, cavities, layering in structural elements, variation of geometry, of moisture content, of materials, areas of decay, defects, cracks have been reported in timber, concrete and masonry elements. Nonetheless, many more fields of investigation remain unexplored. This contribution gives an account of a variety of examples of structural ceilings investigation by GPR radar in reflection mode, either as 2D or 3D data acquisition and visualisation. Ceilings have a pre-eminent role in buildings as they contribute to a good structural behaviour of the construction. Primarily, the following functions can be listed for ceilings: a) they carry vertical dead and live loads on floors and distribute such loads to the vertical walls; b) they oppose to external horizontal forces such as wind loads and earthquakes helping to transfer such forces from the loaded element to the other walls; c) they contribute to create the box skeleton and behaviour of a building, connecting the different load bearing walls and reducing the slenderness and flexural instability of such walls. Therefore, knowing how ceilings are made in specific buildings is of paramount importance for architects and structural engineers. According to the type of building and age of construction, ceilings may present very different solutions and materials. Moreover, in existing constructions, ceilings may have been substituted, modified or strengthened due to material decay or to change of use of the building. These alterations may often go unrecorded in technical documentation or technical drawings may be unavailable. In many cases, the position, orientation and number of the load carrying elements in ceilings may be hidden or not be in sight, due for example to the presence of false ceilings or to technical plants. GPR radar can constitute a very useful tool for investigating with rapidity and high resolution, thin as well as very thick ceilings, in a non-destructive manner. Ceilings may be made up as masonry vaults or timber/metal/concrete beams and elements laid down in one or two directions or, again, can be made as a combination of the above. A number of cases are here presented reporting on typical features to be recognised in radargrams in order to distinguish the material and possible shape of the relevant objects with the aim of providing a first small catalogue useful to the radar user and to professionals. This abstract is of interest for COST Action TU1208.

  12. EFM data mapped into 2D images of tip-sample contact potential difference and capacitance second derivative

    PubMed Central

    Lilliu, S.; Maragliano, C.; Hampton, M.; Elliott, M.; Stefancich, M.; Chiesa, M.; Dahlem, M. S.; Macdonald, J. E.

    2013-01-01

    We report a simple technique for mapping Electrostatic Force Microscopy (EFM) bias sweep data into 2D images. The method allows simultaneous probing, in the same scanning area, of the contact potential difference and the second derivative of the capacitance between tip and sample, along with the height information. The only required equipment consists of a microscope with lift-mode EFM capable of phase shift detection. We designate this approach as Scanning Probe Potential Electrostatic Force Microscopy (SPP-EFM). An open-source MATLAB Graphical User Interface (GUI) for images acquisition, processing and analysis has been developed. The technique is tested with Indium Tin Oxide (ITO) and with poly(3-hexylthiophene) (P3HT) nanowires for organic transistor applications. PMID:24284731

  13. Visualization of aerocolloidal biological particles using 2D particle image velocimetry (PIV)

    NASA Astrophysics Data System (ADS)

    Hall, Carsie A., III; Masabattula, Sree; Akyuzlu, Kazim M.; Russo, Edwin P.; Klich, Maren A.

    2003-11-01

    Recent concerns over the possible use of airborne biological particles as weapons of mass destruction have significantly increased the attention that researchers are giving to this threat. The size of these particles, ranging from a fraction of a micrometer to several tens of micrometers, allows them to travel over long distances before settling out of the airstreams carrying these particles. Furthermore, the odd shapes of many of these particles along with uncertainties about their light scattering characteristics make detection and tracking quite a challenge. In the present paper, results are reported on the visualization of airborne biological particles using two-dimensional particle image velocimetry (PIV). These initial results show the utility of PIV in illuminating and tracking airborne biological particles. A compressed air nebulizer is used to aerosolize the biological particles inside a Plexiglas test section. The biological particles prepared for the nebulizer are first inoculated and cultured onto agar media, gypsum board, and acoustic ceiling tile to achieve an abundant growth of spores. A colloidal suspension of biological particles is then made using sterilized, de-ionized water and a mild surfactant to de-agglomerate the biological particles in the suspension. The concentration of biological particles in the colloidal suspension is determined using a hemacytometer. In the visualization experiments, images are captured for polystyrene latex (PSL) test particles, liquid water droplets, and spores of the fungal species Aspergillus versicolor. During the PIV system operation, two successive images are captured with a time delay of 50 μm to develop flow field velocities of the PSL test particles, liquid water droplets, and the A. versicolor spores.

  14. Image quality improvement for a 3D structure exhibiting multiple 2D patterns and its implementation.

    PubMed

    Hirayama, Ryuji; Nakayama, Hirotaka; Shiraki, Atsushi; Kakue, Takashi; Shimobaba, Tomoyoshi; Ito, Tomoyoshi

    2016-04-01

    A three-dimensional (3D) structure designed by our proposed algorithm can simultaneously exhibit multiple two-dimensional patterns. The 3D structure provides multiple patterns having directional characteristics by distributing the effects of the artefacts. In this study, we proposed an iterative algorithm to improve the image quality of the exhibited patterns and have verified the effectiveness of the proposed algorithm using numerical simulations. Moreover, we fabricated different 3D glass structures (an octagonal prism, a cube and a sphere) using the proposed algorithm. All 3D structures exhibit four patterns, and different patterns can be observed depending on the viewing direction. PMID:27137021

  15. Application of Compressed Sensing to 2-D Ultrasonic Propagation Imaging System data

    SciTech Connect

    Mascarenas, David D.; Farrar, Charles R.; Chong, See Yenn; Lee, J.R.; Park, Gyu Hae; Flynn, Eric B.

    2012-06-29

    The Ultrasonic Propagation Imaging (UPI) System is a unique, non-contact, laser-based ultrasonic excitation and measurement system developed for structural health monitoring applications. The UPI system imparts laser-induced ultrasonic excitations at user-defined locations on a structure of interest. The response of these excitations is then measured by piezoelectric transducers. By using appropriate data reconstruction techniques, a time-evolving image of the response can be generated. A representative measurement of a plate might contain 800x800 spatial data measurement locations and each measurement location might be sampled at 500 instances in time. The result is a total of 640,000 measurement locations and 320,000,000 unique measurements. This is clearly a very large set of data to collect, store in memory and process. The value of these ultrasonic response images for structural health monitoring applications makes tackling these challenges worthwhile. Recently compressed sensing has presented itself as a candidate solution for directly collecting relevant information from sparse, high-dimensional measurements. The main idea behind compressed sensing is that by directly collecting a relatively small number of coefficients it is possible to reconstruct the original measurement. The coefficients are obtained from linear combinations of (what would have been the original direct) measurements. Often compressed sensing research is simulated by generating compressed coefficients from conventionally collected measurements. The simulation approach is necessary because the direct collection of compressed coefficients often requires compressed sensing analog front-ends that are currently not commercially available. The ability of the UPI system to make measurements at user-defined locations presents a unique capability on which compressed measurement techniques may be directly applied. The application of compressed sensing techniques on this data holds the potential to reduce the number of required measurement locations, reduce the time to make measurements, reduce the memory required to store the measurements, and possibly reduce the computational burden to classify the measurements. This work considers the appropriate selection of the signal dictionary used for signal reconstruction, and performs an evaluation of compressed sensing technique's ability to reconstruct ultrasonic images using fewer measurements than would be needed using traditional Nyquist-limited data collection techniques.

  16. 2D and 3D imaging of mound structures from GPR measurements in Danish and Swedish limestone quarries

    NASA Astrophysics Data System (ADS)

    Schack von Brockdorff, A.; Nielsen, L.; Boldreel, L. O.; Overgaard, T.

    2003-04-01

    High-resolution 2D and 3D images of limestone mound structures are obtained from GPR measurements made in limestone quarries located in southwest Sweden and Zealand, Denmark. The centre frequency of the employed antennas is 100 MHz, and the reflected GPR signals offer a vertical resolution of about 0.5 m of the internal layering of the limestone deposits. A depth penetration of 10 m is obtained. The GPR data are collected along profiles (2D imaging) and in rectangular grids (3D imaging). The investigated mound structures are of Danian age. They formed through the growth of bryozoans just below the photic zone in a cool-water environment. The observed GPR reflectivity is caused by contrasts in the physical properties between: 1) chalk layers and flint layers; 2) erosional surfaces (e.g. hardgrounds) and the layers above and below; and 3) chalk layers of different composition, porosity and/or texture. The GPR data are processed using standard seismic processing procedures (e.g. bandpass filtering and migration). The tools included in the ProMAX processing package are used for these purposes. The flanks and the internal layers of the observed mounds often dip more than 30 degrees. Therefore, proper migration of the GPR signals is essential for obtaining trustworthy images of the detailed mound structures. The data are interpreted using the PC-based software SeisVision. We find that typical mounds have widths and lengths on the order of 50 m and heights of 5-10 m. The mound structures mapped in southwest Sweden and Denmark share many common characteristics in terms of size and spatial distribution, and the internal structures of the mounds may hold the key for interpreting the geological history (e.g. growth direction) of the mounds.

  17. Tangential 2-D Edge Imaging for GPI and Edge/Impurity Modeling

    SciTech Connect

    Dr. Ricardo Maqueda; Dr. Fred M. Levinton

    2011-12-23

    Nova Photonics, Inc. has a collaborative effort at the National Spherical Torus Experiment (NSTX). This collaboration, based on fast imaging of visible phenomena, has provided key insights on edge turbulence, intermittency, and edge phenomena such as edge localized modes (ELMs) and multi-faceted axisymmetric radiation from the edge (MARFE). Studies have been performed in all these areas. The edge turbulence/intermittency studies make use of the Gas Puff Imaging diagnostic developed by the Principal Investigator (Ricardo Maqueda) together with colleagues from PPPL. This effort is part of the International Tokamak Physics Activity (ITPA) edge, scrape-off layer and divertor group joint activity (DSOL-15: Inter-machine comparison of blob characteristics). The edge turbulence/blob study has been extended from the current location near the midplane of the device to the lower divertor region of NSTX. The goal of this effort was to study turbulence born blobs in the vicinity of the X-point region and their circuit closure on divertor sheaths or high density regions in the divertor. In the area of ELMs and MARFEs we have studied and characterized the mode structure and evolution of the ELM types observed in NSTX, as well as the study of the observed interaction between MARFEs and ELMs. This interaction could have substantial implications for future devices where radiative divertor regions are required to maintain detachment from the divertor plasma facing components.

  18. SIMS of organics—Advances in 2D and 3D imaging and future outlook

    SciTech Connect

    Gilmore, Ian S.

    2013-09-15

    Secondary ion mass spectrometry (SIMS) has become a powerful technique for the label-free analysis of organics from cells to electronic devices. The development of cluster ion sources has revolutionized the field, increasing the sensitivity for organics by two or three orders of magnitude and for large clusters, such as C{sub 60} and argon clusters, allowing depth profiling of organics. The latter has provided the capability to generate stunning three dimensional images with depth resolutions of around 5 nm, simply unavailable by other techniques. Current state-of-the-art allows molecular images with a spatial resolution of around 500 nm to be achieved and future developments are likely to progress into the sub-100 nm regime. This review is intended to bring those with some familiarity with SIMS up-to-date with the latest developments for organics, the fundamental principles that underpin this and define the future progress. State-of-the-art examples are showcased and signposts to more in-depth reviews about specific topics given for the specialist.

  19. Body edge delineation in 2D DC resistivity imaging using differential method

    NASA Astrophysics Data System (ADS)

    Susanto, Kusnahadi; Fitrah Bahari, Mohammad

    2016-01-01

    DC resistivity is widely used to identify the kind of rock and the lithology contact. However, the image resulting from resistivity processing is shown in a contour image. There is be a problem to interpret where the edge of body location is. This study uses differential method to delineate the edge of body in DC resistivity contour. This method was applied to the boundary between gravel and underlying clay layer. The first and the second order differential method is applied to the delineation of lithology contact. The profiling curve has to be sliced and extracted from the resistivity contour before the differential method can be used. The spectral analysis shows the frequency and wavenumber of the profiling curve used to make gridding. The slicing process was conducted horizontally and vertically in order to get the mesh size which will be used in the differential method. The second order differential, the Laplace operator, is able to show the edge of body more clearly than the first order differential and shows the contact between gravel and clay.

  20. A new computational approach to cracks quantification from 2D image analysis: Application to micro-cracks description in rocks

    NASA Astrophysics Data System (ADS)

    Arena, Alessio; Delle Piane, Claudio; Sarout, Joel

    2014-05-01

    In this paper we propose a crack quantification method based on 2D image analysis. This technique is applied to a gray level Scanning Electron Microscope (SEM) images, segmented and converted in Black and White (B/W) images using the Trainable Segmentation plugin of Fiji. Resulting images are processed using a novel Matlab script composed of three different algorithms: the separation algorithm, the filtering and quantification algorithm and the orientation one. Initially the input image is enhanced via 5 morphological processes. The resulting lattice is “cut” into single cracks using 1 pixel-wide bisector lines originated from every node. Cracks are labeled using the connected-component method, then the script computes geometrical parameters, such as width, length, area, aspect ratio and orientation. A filtering is performed using a user-defined value of aspect ratio, followed by a statistical analysis of remaining cracks. In the last part of this paper we discuss about the efficiency of this script, introducing an example of analysis of two datasets with different dimension and resolution; these analyses are performed using a notebook and a high-end professional desktop solution, in order to simulate different working environments.

  1. Intensifying the response of distributed optical fibre sensors using 2D and 3D image restoration

    PubMed Central

    Soto, Marcelo A.; Ramírez, Jaime A.; Thévenaz, Luc

    2016-01-01

    Distributed optical fibre sensors possess the unique capability of measuring the spatial and temporal map of environmental quantities that can be of great interest for several field applications. Although existing methods for performance enhancement have enabled important progresses in the field, they do not take full advantage of all information present in the measured data, still giving room for substantial improvement over the state-of-the-art. Here we propose and experimentally demonstrate an approach for performance enhancement that exploits the high level of similitude and redundancy contained on the multidimensional information measured by distributed fibre sensors. Exploiting conventional image and video processing, an unprecedented boost in signal-to-noise ratio and measurement contrast is experimentally demonstrated. The method can be applied to any white-noise-limited distributed fibre sensor and can remarkably provide a 100-fold improvement in the sensor performance with no hardware modification. PMID:26927698

  2. 2D turbulence imaging in DIII-D via beam emission spectroscopy

    SciTech Connect

    Fenzi, C.; Fonck, R. J.; Jakubowski, M.; Mc Kee, G. R.

    2001-01-01

    Two-dimensional measurements of density fluctuations have been performed in DIII-D using the beam emission spectroscopy diagnostic. The 32 spatial channels are arranged to image a 5x6cm{sup 2} (radialxpoloidal) region in the plasma cross section, at a nominal 1 cm spatial resolution and separation. The typical decorrelation time, poloidal and radial correlation lengths, as well as a time-averaged flow field plot are obtained from spatial and temporal correlation analyses. A biorthogonal decomposition algorithm is applied to expand the data set into a set of modes that are orthogonal in time and in space, thus providing a simultaneous analysis of the space and time dependencies of fluctuation data.

  3. Intensifying the response of distributed optical fibre sensors using 2D and 3D image restoration

    NASA Astrophysics Data System (ADS)

    Soto, Marcelo A.; Ramírez, Jaime A.; Thévenaz, Luc

    2016-03-01

    Distributed optical fibre sensors possess the unique capability of measuring the spatial and temporal map of environmental quantities that can be of great interest for several field applications. Although existing methods for performance enhancement have enabled important progresses in the field, they do not take full advantage of all information present in the measured data, still giving room for substantial improvement over the state-of-the-art. Here we propose and experimentally demonstrate an approach for performance enhancement that exploits the high level of similitude and redundancy contained on the multidimensional information measured by distributed fibre sensors. Exploiting conventional image and video processing, an unprecedented boost in signal-to-noise ratio and measurement contrast is experimentally demonstrated. The method can be applied to any white-noise-limited distributed fibre sensor and can remarkably provide a 100-fold improvement in the sensor performance with no hardware modification.

  4. Intensifying the response of distributed optical fibre sensors using 2D and 3D image restoration.

    PubMed

    Soto, Marcelo A; Ramírez, Jaime A; Thévenaz, Luc

    2016-01-01

    Distributed optical fibre sensors possess the unique capability of measuring the spatial and temporal map of environmental quantities that can be of great interest for several field applications. Although existing methods for performance enhancement have enabled important progresses in the field, they do not take full advantage of all information present in the measured data, still giving room for substantial improvement over the state-of-the-art. Here we propose and experimentally demonstrate an approach for performance enhancement that exploits the high level of similitude and redundancy contained on the multidimensional information measured by distributed fibre sensors. Exploiting conventional image and video processing, an unprecedented boost in signal-to-noise ratio and measurement contrast is experimentally demonstrated. The method can be applied to any white-noise-limited distributed fibre sensor and can remarkably provide a 100-fold improvement in the sensor performance with no hardware modification. PMID:26927698

  5. A temperature dependent 2D-ACAR study of untwinned metallic YBa{sub 2}Cu{sub 3}O{sub 7{minus}x}

    SciTech Connect

    Smedskjaer, L.C.; Welp, U.; Fang, Y.; Bailey, K.G.; Bansil, A.

    1992-02-01

    The authors have carried out 2D-ACAR measurements in the c-axis projection on an untwinned single crystal of YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} as a function of temperature, for five temperatures ranging from 30K to 300K. These temperature dependent 2D-ACAR spectra can be approximated by a superposition of two temperature independent spectra with temperature dependent weighting factors. The authors discuss how the temperature dependence of the data can be exploited to obtain a {open_quote}background corrected{close_quote} experimental spectrum, which is found to be in remarkable accord with the corresponding band theory based predictions, including for the first time the overall amplitude of the anisotropy in the 2D-ACAR. The corrected data also show clear signatures of the ridge Fermi surface and an indication of the pillbox surface.

  6. Evaluation of the spatial dependence of the point spread function in 2D PET image reconstruction using LOR-OSEM

    PubMed Central

    Wiant, D.; Gersh, J. A.; Bennett, M.; Bourland, J. D.

    2010-01-01

    Purpose: The use of positron emission tomography (PET) imaging has proved beneficial in the staging and diagnosis of several cancer disease sites. Additional applications of PET imaging in treatment planning and the evaluation of treatment response are limited by the relatively low spatial resolution of PET images. Including point spread function (PSF) information in the system matrix (SM) of iterative reconstruction techniques has been shown to produce improved spatial resolution in PET images. Methods: In this study, the authors sampled the spatially variant PSF at over 6000 locations in the field of view for a General Electric Discovery ST PET∕CT (General Electric Healthcare, Waukesha, WI) scanner in 2D acquisition mode. The authors developed PSF blurred SMs based on different combinations of the radial, depth, and azimuthal spatial dependencies to test the overall spatial dependence of the PSF on image quality. The PSF blurred SMs were included in a LOR-OSEM reconstruction algorithm and used for image reconstruction of geometric phantoms. The authors also examined the effect of sampling density on PSF characterization to design a more efficient sampling scheme. Results: The authors found that depth dependent change in the amplitude of the detector response was the most important factor affecting image quality. A SM created from a PSF that introduced r (perpendicular to the LOR), d (parallel to the LOR), or r and d dependent blurring across the radial lines of response led to visually identifiable improvements in spatial resolution and contrast in reconstructed images compared to images reconstructed with a purely geometric SM with no PSF blurring. Images reconstructed using a SM with r and d dependent blurring across the radial lines of response showed improved spatial resolution and contrast-noise ratios compared to images reconstructed with a SM that had only r dependent blurring. Additionally, the authors determined that the PSF could be adequately characterized with roughly 85% fewer samples through the use of a better optimized sampling scheme. Conclusions: PET image reconstruction using a SM made from an accurately characterized PSF that accounts for r and d dependencies results in improved spatial resolution and contrast-noise relations, which may aid in lesion boundary detection for treatment planning or quantitative assessment of treatment response. PMID:20384254

  7. Enhancing LTW image encoder with perceptual coding and GPU-optimized 2D-DWT transform

    NASA Astrophysics Data System (ADS)

    Martínez-Rach, Miguel O.; López-Granado, Otoniel; Galiano, Vicente; Migallón, Hector; Llor, Jesús; Malumbres, Manuel P.

    2013-12-01

    When optimizing a wavelet image coder, the two main targets are to (1) improve its rate-distortion (R/D) performance and (2) reduce the coding times. In general, the encoding engine is mainly responsible for achieving R/D performance. It is usually more complex than the decoding part. A large number of works about R/D or complexity optimizations can be found, but only a few tackle the problem of increasing R/D performance while reducing the computational cost at the same time, like Kakadu, an optimized version of JPEG2000. In this work we propose an optimization of the E_LTW encoder with the aim to increase its R/D performance through perceptual encoding techniques and reduce the encoding time by means of a graphics processing unit-optimized version of the two-dimensional discrete wavelet transform. The results show that in both performance dimensions, our enhanced encoder achieves good results compared with Kakadu and SPIHT encoders, achieving speedups of 6 times with respect to the original E_LTW encoder.

  8. Hartree-Fock Solutions of 2d Interacting Tight-Binding Electrons: Mott Properties and Room Temperature Superconductivity Indications

    NASA Astrophysics Data System (ADS)

    Cabo Montes de Oca, A.; March, N. H.; Cabo-Bizet, A.

    2014-12-01

    Former results for a tight-binding (TB) model of CuO planes in La2CuO4 are reinterpreted here to underline their wider implications. It is noted that physical systems being appropriately described by the TB model can exhibit the main strongly correlated electron system (SCES) properties, when they are solved in the HF approximation, by also allowing crystal symmetry breaking effects and noncollinear spin orientations of the HF orbitals. It is argued how a simple 2D square lattice system of Coulomb interacting electrons can exhibit insulator gaps and pseudogap states, and quantum phase transitions as illustrated by the mentioned former works. A discussion is also presented here indicating the possibility of attaining room temperature superconductivity, by means of a surface coating with water molecules of cleaved planes of graphite, being orthogonal to its c-axis. The possibility that 2D arrays of quantum dots can give rise to the same effect is also proposed to consideration. The analysis also furnishes theoretical insight to solve the Mott-Slater debate, at least for the La2CuO4 and TMO band structures. The idea is to apply a properly noncollinear GW scheme to the electronic structure calculation of these materials. The fact is that the GW approach can be viewed as a HF procedure in which the screening polarization is also determined. This directly indicates the possibility of predicting the assumed dielectric constant in the previous works. Thus, the results seem to identify that the main correlation properties in these materials are determined by screening. Finally, the conclusions also seem to be of help for the description of the experimental observations of metal-insulator transitions and Mott properties in atoms trapped in planar photonic lattices.

  9. Ceria-Zirconia Particles Wrapped in a 2D Carbon Envelope: Improved Low-Temperature Oxygen Transfer and Oxidation Activity.

    PubMed

    Aneggi, Eleonora; Rico-Perez, Veronica; de Leitenburg, Carla; Maschio, Stefano; Soler, Lluís; Llorca, Jordi; Trovarelli, Alessandro

    2015-11-16

    Engineering the interface between different components of heterogeneous catalysts at nanometer level can radically alter their performances. This is particularly true for ceria-based catalysts where the interactions are critical for obtaining materials with enhanced properties. Here we show that mechanical contact achieved by high-energy milling of CeO2 -ZrO2 powders and carbon soot results in the formation of a core of oxide particles wrapped in a thin carbon envelope. This 2D nanoscale carbon arrangement greatly increases the number and quality of contact points between the oxide and carbon. Consequently, the temperatures of activation and transfer of the oxygen in ceria are shifted to exceptionally low temperatures and the soot combustion rate is boosted. The study confirms the importance of the redox behavior of ceria-zirconia particles in the mechanism of soot oxidation and shows that the organization of contact points at the nanoscale can significantly modify the reactivity resulting in unexpected properties and functionalities. PMID:26448053

  10. Ceria–Zirconia Particles Wrapped in a 2D Carbon Envelope: Improved Low-Temperature Oxygen Transfer and Oxidation Activity

    PubMed Central

    Aneggi, Eleonora; Rico-Perez, Veronica; de Leitenburg, Carla; Maschio, Stefano; Soler, Lluís; Llorca, Jordi; Trovarelli, Alessandro

    2015-01-01

    Engineering the interface between different components of heterogeneous catalysts at nanometer level can radically alter their performances. This is particularly true for ceria-based catalysts where the interactions are critical for obtaining materials with enhanced properties. Here we show that mechanical contact achieved by high-energy milling of CeO2–ZrO2 powders and carbon soot results in the formation of a core of oxide particles wrapped in a thin carbon envelope. This 2D nanoscale carbon arrangement greatly increases the number and quality of contact points between the oxide and carbon. Consequently, the temperatures of activation and transfer of the oxygen in ceria are shifted to exceptionally low temperatures and the soot combustion rate is boosted. The study confirms the importance of the redox behavior of ceria-zirconia particles in the mechanism of soot oxidation and shows that the organization of contact points at the nanoscale can significantly modify the reactivity resulting in unexpected properties and functionalities. PMID:26448053

  11. The cone penetration test and 2D imaging resistivity as tools to simulate the distribution of hydrocarbons in soil

    NASA Astrophysics Data System (ADS)

    Pérez-Corona, M.; García, J. A.; Taller, G.; Polgár, D.; Bustos, E.; Plank, Z.

    2016-02-01

    The purpose of geophysical electrical surveys is to determine the subsurface resistivity distribution by making measurements on the ground surface. From these measurements, the true resistivity of the subsurface can be estimated. The ground resistivity is related to various geological parameters, such as the mineral and fluid content, porosity and degree of water saturation in the rock. Electrical resistivity surveys have been used for many decades in hydrogeological, mining and geotechnical investigations. More recently, they have been used for environmental surveys. To obtain a more accurate subsurface model than is possible with a simple 1-D model, a more complex model must be used. In a 2-D model, the resistivity values are allowed to vary in one horizontal direction (usually referred to as the x direction) but are assumed to be constant in the other horizontal (the y) direction. A more realistic model would be a fully 3-D model where the resistivity values are allowed to change in all three directions. In this research, a simulation of the cone penetration test and 2D imaging resistivity are used as tools to simulate the distribution of hydrocarbons in soil.

  12. Design and analysis of directional 2D nonseparable perfect reconstruction filter banks for subband coding of images and video signals

    NASA Astrophysics Data System (ADS)

    Huang, Chang-Lin; Lien, Chen-Chang

    1992-11-01

    In this paper, we develop a directional 2-D non-separable filter bank which can perform the perfect reconstruction of the downsampled subband signals. The filter bank represents a union of two powerful image and video processing tools: directional decomposition and subband decomposition. This subband decomposition is implemented by: (1) shifting the input signal and the subband signals; (2) using a tree-structure diamond shape prefilter followed by downsampling on quincunx grids; and (3) applying four types parallelogram prefilters followed by four different downsampling matrices respectively. This paper addresses the design and implementation of two-channel filter banks for such applications. The two-band subsystem in the tree-structure filter bank is proved and analyzed to be able to provide perfect reconstruction of the downsampled subband signals. Our method is extremely computationally simple in designing the analysis/synthesis subfilters for the filter bank without using any nonlinearly constrained numerical optimization. Finally, we use conventional 1-D analysis/synthesis filters as prototype and then apply McClellan transform for the specific 2-D diamond shape and parallelogram shape sub-filters.

  13. Leaf Area Index Estimation in Vineyards from Uav Hyperspectral Data, 2d Image Mosaics and 3d Canopy Surface Models

    NASA Astrophysics Data System (ADS)

    Kalisperakis, I.; Stentoumis, Ch.; Grammatikopoulos, L.; Karantzalos, K.

    2015-08-01

    The indirect estimation of leaf area index (LAI) in large spatial scales is crucial for several environmental and agricultural applications. To this end, in this paper, we compare and evaluate LAI estimation in vineyards from different UAV imaging datasets. In particular, canopy levels were estimated from i.e., (i) hyperspectral data, (ii) 2D RGB orthophotomosaics and (iii) 3D crop surface models. The computed canopy levels have been used to establish relationships with the measured LAI (ground truth) from several vines in Nemea, Greece. The overall evaluation indicated that the estimated canopy levels were correlated (r2 > 73%) with the in-situ, ground truth LAI measurements. As expected the lowest correlations were derived from the calculated greenness levels from the 2D RGB orthomosaics. The highest correlation rates were established with the hyperspectral canopy greenness and the 3D canopy surface models. For the later the accurate detection of canopy, soil and other materials in between the vine rows is required. All approaches tend to overestimate LAI in cases with sparse, weak, unhealthy plants and canopy.

  14. Instantaneous 2D Velocity and Temperature Measurements in High Speed Flows Based on Spectrally Resolved Molecular Rayleigh Scattering

    NASA Technical Reports Server (NTRS)

    Seasholtz, Richard G.

    1995-01-01

    A Rayleigh scattering diagnostic for high speed flows is described for the simultaneous, instantaneous measurement of gas temperature and velocity at a number (up to about one hundred) of locations in a plane illuminated by an injection-seeded, frequency doubled Nd:YAG laser. Molecular Rayleigh scattered light is collected and passed through a planar mirror Fabry-Perot interferometer. The resulting image is analyzed to determine the gas temperature and bulk velocity at each of the regions. The Cramer Rao lower bound for measurement uncertainty is calculated. Experimental data is presented for a free jet and for preliminary measurements in the Lewis 4 inch by 10 inch supersonic wind tunnel.

  15. Registration of dynamic multiview 2D ultrasound and late gadolinium enhanced images of the heart: Application to hypertrophic cardiomyopathy characterization.

    PubMed

    Betancur, Julián; Simon, Antoine; Halbert, Edgar; Tavard, François; Carré, François; Hernández, Alfredo; Donal, Erwan; Schnell, Frédéric; Garreau, Mireille

    2016-02-01

    Describing and analyzing heart multiphysics requires the acquisition and fusion of multisensor cardiac images. Multisensor image fusion enables a combined analysis of these heterogeneous modalities. We propose to register intra-patient multiview 2D+t ultrasound (US) images with multiview late gadolinium-enhanced (LGE) images acquired during cardiac magnetic resonance imaging (MRI), in order to fuse mechanical and tissue state information. The proposed procedure registers both US and LGE to cine MRI. The correction of slice misalignment and the rigid registration of multiview LGE and cine MRI are studied, to select the most appropriate similarity measure. It showed that mutual information performs the best for LGE slice misalignment correction and for LGE and cine registration. Concerning US registration, dynamic endocardial contours resulting from speckle tracking echocardiography were exploited in a geometry-based dynamic registration. We propose the use of an adapted dynamic time warping procedure to synchronize cardiac dynamics in multiview US and cine MRI. The registration of US and LGE MRI was evaluated on a dataset of patients with hypertrophic cardiomyopathy. A visual assessment of 330 left ventricular regions from US images of 28 patients resulted in 92.7% of regions successfully aligned with cardiac structures in LGE. Successfully-aligned regions were then used to evaluate the abilities of strain indicators to predict the presence of fibrosis. Longitudinal peak-strain and peak-delay of aligned left ventricular regions were computed from corresponding regional strain curves from US. The Mann-Withney test proved that the expected values of these indicators change between the populations of regions with and without fibrosis (p < 0.01). ROC curves otherwise proved that the presence of fibrosis is one factor amongst others which modifies longitudinal peak-strain and peak-delay. PMID:26619189

  16. Study of the Bursting Behavior of Type-I ELM Filaments on KSTAR by 2-D ECE Imaging System

    NASA Astrophysics Data System (ADS)

    Lee, J.; Yun, G. S.; Choi, M. J.; Lee, W.; Park, H. K.; Lee, J. H.; Domier, C. W.; Luhmann, N. C., Jr.; Donné, A. J. H.; Tobias, B.; Kstar Team

    2011-10-01

    Edge Localized Modes (ELMs), repetitive relaxation of the excess pressure and/or current density at the edge of the H-mode plasmas, have been studied in 2-D during the 2010 KSTAR campaign using an electron cyclotron emission imaging (ECEI) diagnostics. More comprehensive picture of type-I ELMs compared to the previous campaign has been obtained in 2011 and the complex crash dynamics of the ELM filaments have been investigated in more detail. The growth rate, the filament size, and the poloidal flow are compared between type-I ELMs and type-III ELMs. In particular, type-I ELMs are observed to involve larger change in the poloidal flow during the crash phase and have much longer transient phase (~ 10 ms), a critical stage characterized by an abrupt change in the poloidal mode number preceding the crash. Work supported by NRF Korea, US DOE, and the Euratom-FOM association.

  17. 2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements

    SciTech Connect

    Lin, L. Ding, W. X.; Brower, D. L.

    2014-11-15

    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.

  18. Interferometry based multispectral photon-limited 2D and 3D integral image encryption employing the Hartley transform.

    PubMed

    Muniraj, Inbarasan; Guo, Changliang; Lee, Byung-Geun; Sheridan, John T

    2015-06-15

    We present a method of securing multispectral 3D photon-counted integral imaging (PCII) using classical Hartley Transform (HT) based encryption by employing optical interferometry. This method has the simultaneous advantages of minimizing complexity by eliminating the need for holography recording and addresses the phase sensitivity problem encountered when using digital cameras. These together with single-channel multispectral 3D data compactness, the inherent properties of the classical photon counting detection model, i.e. sparse sensing and the capability for nonlinear transformation, permits better authentication of the retrieved 3D scene at various depth cues. Furthermore, the proposed technique works for both spatially and temporally incoherent illumination. To validate the proposed technique simulations were carried out for both the 2D and 3D cases. Experimental data is processed and the results support the feasibility of the encryption method. PMID:26193568

  19. 2D Soft X-ray System for Imaging Magnetic Topology in the Pedestal Region on DIII-D

    NASA Astrophysics Data System (ADS)

    Shafer, M. W.; Battaglia, D. J.; Unterberg, E. A.; Canik, J.; Hillis, D. L.; Maingi, R.; Evans, T. E.

    2010-11-01

    A new tangential 2D Soft X-ray Imaging System (SXRIS) is designed to examine the edge magnetic island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of applied resonant magnetic perturbations (RMPs) may play a role in the suppression of edge localized modes. The SXRIS will aid in determining the 3D magnetic structure due to applied RMPs. A synthetic diagnostic calculation based on 3D SXRIS emissivity estimates calibrated against NSTX data, shows a signal-to-noise ratio of 10 with 1 cm resolution for a 25 ms integration time. Impurity puffing is expected to increase the SNR further. Image inversion is required but is an ill-posed problem, requiring symmetry assumptions such as constant emission along field lines. Advanced inversion methods are examined in the context of noise, spatial sensitivity, and symmetry assumptions. Forward modeling is used to compare 3D equilibria, e.g. from SIESTA, and simulated images to examine the non-ideal plasma response.

  20. Transverse Strains in Muscle Fascicles during Voluntary Contraction: A 2D Frequency Decomposition of B-Mode Ultrasound Images

    PubMed Central

    Wakeling, James M.

    2014-01-01

    When skeletal muscle fibres shorten, they must increase in their transverse dimensions in order to maintain a constant volume. In pennate muscle, this transverse expansion results in the fibres rotating to greater pennation angle, with a consequent reduction in their contractile velocity in a process known as gearing. Understanding the nature and extent of this transverse expansion is necessary to understand the mechanisms driving the changes in internal geometry of whole muscles during contraction. Current methodologies allow the fascicle lengths, orientations, and curvatures to be quantified, but not the transverse expansion. The purpose of this study was to develop and validate techniques for quantifying transverse strain in skeletal muscle fascicles during contraction from B-mode ultrasound images. Images were acquired from the medial and lateral gastrocnemii during cyclic contractions, enhanced using multiscale vessel enhancement filtering and the spatial frequencies resolved using 2D discrete Fourier transforms. The frequency information was resolved into the fascicle orientations that were validated against manually digitized values. The transverse fascicle strains were calculated from their wavelengths within the images. These methods showed that the transverse strain increases while the longitudinal fascicle length decreases; however, the extent of these strains was smaller than expected. PMID:25328509

  1. Evaluation of 3D vs. 2D compression of medical images with set partitioning in hierarchical trees

    NASA Astrophysics Data System (ADS)

    Manduca, Armando; Persons, Kenneth R.; Erickson, Bradley J.; Palisson, Patrice M.

    1998-06-01

    Wavelet-based image compression is a very effective technique for medical images, giving significantly better results than the JPEG algorithm. Recent advanced wavelet techniques, such as embedded zerotree wavelet coding or set partitioning in hierarchical trees (SPIHT), have further improved compression efficiency by exploiting the natural relationship between corresponding coefficients at different scales and by progressively refining coefficient values. It is also well known that full 3-D wavelet compression of 3-D data sets is significantly more efficient than 2-D compression of individual slices, but the memory requirements are very high. We explore the extension of the SPIHT algorithm to three dimensions, and also of intermediate approaches such as the encoding of a 3-D image in 'slabs' of 16 slices at a time or simple subtraction of neighboring slices, which yield different tradeoffs between speed and memory requirements on the one hand and compression efficiency on the other for a variety of possible approaches on typical 3-D CT and MRI data sets.

  2. Transverse Strains in Muscle Fascicles during Voluntary Contraction: A 2D Frequency Decomposition of B-Mode Ultrasound Images.

    PubMed

    Wakeling, James M; Randhawa, Avleen

    2014-01-01

    When skeletal muscle fibres shorten, they must increase in their transverse dimensions in order to maintain a constant volume. In pennate muscle, this transverse expansion results in the fibres rotating to greater pennation angle, with a consequent reduction in their contractile velocity in a process known as gearing. Understanding the nature and extent of this transverse expansion is necessary to understand the mechanisms driving the changes in internal geometry of whole muscles during contraction. Current methodologies allow the fascicle lengths, orientations, and curvatures to be quantified, but not the transverse expansion. The purpose of this study was to develop and validate techniques for quantifying transverse strain in skeletal muscle fascicles during contraction from B-mode ultrasound images. Images were acquired from the medial and lateral gastrocnemii during cyclic contractions, enhanced using multiscale vessel enhancement filtering and the spatial frequencies resolved using 2D discrete Fourier transforms. The frequency information was resolved into the fascicle orientations that were validated against manually digitized values. The transverse fascicle strains were calculated from their wavelengths within the images. These methods showed that the transverse strain increases while the longitudinal fascicle length decreases; however, the extent of these strains was smaller than expected. PMID:25328509

  3. Selective coding with controlled quality decay for 2D and 3D images in a JPEG2000 framework

    NASA Astrophysics Data System (ADS)

    Signoroni, Alberto; Lazzaroni, Fabio; Leonardi, Riccardo

    2003-06-01

    This paper presents some ideas which extend the functionality and the application fields of a spatially selective coding within a JPEG2000 framework. At first, the image quality drop between the Regions of Interest (ROI) and the background (BG) is considered. In a conventional approach, the reconstructed image quality steeply drops along the ROI boundary; however, this effect could be considered or perceived objectionable in some use cases. A simple quality decay management is proposed here, which makes use of concentric ROI with different scaling factors. This allows the technique to be perfectly consistent with the JPEG2000 part 2 ROI definition and description. Another considered issue is the extension of the selective ROI coding to a 3D Volume of Interest coding. This extension is currently under consideration for the part 10 of JPEG2000, JP3D. An easy and effective 2D to 3D extension for the VOI definition and description is proposed here: a VOI is defined by a set composition of ROI generated solids, where ROI are defined along one or more volume cutting direction, and is described by the relative set of ROI parameters. Moreover, the quality decay management can be applied to this extension. The proposed techniques could have a significant impact on the selective coding of medical images and volumes. Image quality issues are very important but very critical factors in that field, which also constitutes the dominant market for 3D applications. Therefore, some experiments are presented on medical images and volumes in order evaluate the benefits of the proposed approaches in terms of diagnostic quality improvement with respect to a conventional ROI coding usage.

  4. A Practical Deconvolution Computation Algorithm to Extract 1D Spectra from 2D Images of Optical Fiber Spectroscopy

    NASA Astrophysics Data System (ADS)

    Guangwei, Li; Haotong, Zhang; Zhongrui, Bai

    2015-06-01

    Bolton & Schlegel presented a promising deconvolution method to extract one-dimensional (1D) spectra from a two-dimensional (2D) optical fiber spectral CCD (charge-coupled device) image. The method could eliminate the PSF (point-spread function) difference between fibers, extract spectra to the photo noise level, as well as improve the resolution. But the method is limited by its huge computation requirement and thus can not be implemented in actual data reduction. In this article, we develop a practical computation method to solve the computation problem. The new computation method can deconvolve a 2D fiber spectral image of any size with actual PSFs, which may vary with positions. Our method does not require large amounts of memory and can extract a 4 k × 4 k noise-free CCD image with 250 fibers in 2 hr. To make our method more practical, we further consider the influence of noise, which is thought to be an intrinsic ill-posed problem in deconvolution algorithms. We modify our method with a Tikhonov regularization item to depress the method induced noise. We do a series of simulations to test how our method performs under more real situations with Poisson noise and extreme cross talk. Compared with the results of traditional extraction methods, i.e., the Aperture Extraction Method and the Profile Fitting Method, our method has the least residual and influence by cross talk. For the noise-added image, the computation speed does not depend very much on fiber distance, the signal-to-noise ratio converges in 2-4 iterations, and the computation times are about 3.5 hr for the extreme fiber distance and about 2 hr for nonextreme cases. A better balance between the computation time and result precision could be achieved by setting the precision threshold similar to the noise level. Finally, we apply our method to real LAMOST (Large sky Area Multi-Object fiber Spectroscopic Telescope; a.k.a. Guo Shou Jing Telescope) data. We find that the 1D spectrum extracted by our method has both higher signal-to-noise ratio and resolution than the traditional methods, but there are still some suspicious weak features, possibly caused by the method around the strong emission lines. As we have demonstrated, our deconvolution method has solved the computation problem and progressed in dealing with the noise influence. Multifiber spectra extracted by our method will have higher resolution and signal-to-noise ratio, and thus will provide more accurate information (such as higher radial velocity and metallicity measurement accuracy in stellar physics) to astronomers than traditional methods.

  5. Pressure-induced cooperative spin transition in ironII 2D coordination polymers: room-temperature visible spectroscopic study.

    PubMed

    Levchenko, G; Bukin, G V; Terekhov, S A; Gaspar, A B; Martínez, V; Muñoz, M C; Real, J A

    2011-06-30

    For the 2D coordination polymers [Fe(3-Fpy)(2)M(II)(CN)(4)] (M(II) = Ni, Pd, Pt), the pressure-induced spin crossover behavior has been investigated at 298 K by monitoring the distinct optical properties associated with each spin state. Cooperative first-order spin transition characterized by a piezohysteresis loop ca. 0.1 GPa wide was observed for the three derivatives. Application of the mean field regular solution theory has enabled estimation of the cooperative parameter, Γ(p), and the enthalpy, ΔH(HL)(p), associated with the spin transition for each derivative. These values, found in the intervals 6.8-7.9 and 18.6-20.8 kJ mol(-1), respectively, are consistent with those previously reported for thermally induced spin transition at constant pressure for the title compounds (Chem.-Eur. J.2009, 15, 10960). Relevance of the elastic energy, Δ(elast), as a corrective parameter accounting for the pressure dependence of the critical temperature of thermally induced spin transitions (Clausius-Clapeiron equation) is also demonstrated and discussed. PMID:21599006

  6. A novel approach of computer-aided detection of focal ground-glass opacity in 2D lung CT images

    NASA Astrophysics Data System (ADS)

    Li, Song; Liu, Xiabi; Yang, Ali; Pang, Kunpeng; Zhou, Chunwu; Zhao, Xinming; Zhao, Yanfeng

    2013-02-01

    Focal Ground-Glass Opacity (fGGO) plays an important role in diagnose of lung cancers. This paper proposes a novel approach for detecting fGGOs in 2D lung CT images. The approach consists of two stages: extracting regions of interests (ROIs) and labeling each ROI as fGGO or non-fGGO. In the first stage, we use the techniques of Otsu thresholding and mathematical morphology to segment lung parenchyma from lung CT images and extract ROIs in lung parenchyma. In the second stage, a Bayesian classifier is constructed based on the Gaussian mixture Modeling (GMM) of the distribution of visual features of fGGOs to fulfill ROI identification. The parameters in the classifier are estimated from training data by the discriminative learning method of Max-Min posterior Pseudo-probabilities (MMP). A genetic algorithm is further developed to select compact and discriminative features for the classifier. We evaluated the proposed fGGO detection approach through 5-fold cross-validation experiments on a set of 69 lung CT scans that contain 70 fGGOs. The proposed approach achieves the detection sensitivity of 85.7% at the false positive rate of 2.5 per scan, which proves its effectiveness. We also demonstrate the usefulness of our genetic algorithm based feature selection method and MMP discriminative learning method through comparing them with without-selection strategy and Support Vector Machines (SVMs), respectively, in the experiments.

  7. Robust and highly performant ring detection algorithm for 3d particle tracking using 2d microscope imaging

    PubMed Central

    Afik, Eldad

    2015-01-01

    Three-dimensional particle tracking is an essential tool in studying dynamics under the microscope, namely, fluid dynamics in microfluidic devices, bacteria taxis, cellular trafficking. The 3d position can be determined using 2d imaging alone by measuring the diffraction rings generated by an out-of-focus fluorescent particle, imaged on a single camera. Here I present a ring detection algorithm exhibiting a high detection rate, which is robust to the challenges arising from ring occlusion, inclusions and overlaps, and allows resolving particles even when near to each other. It is capable of real time analysis thanks to its high performance and low memory footprint. The proposed algorithm, an offspring of the circle Hough transform, addresses the need to efficiently trace the trajectories of many particles concurrently, when their number in not necessarily fixed, by solving a classification problem, and overcomes the challenges of finding local maxima in the complex parameter space which results from ring clusters and noise. Several algorithmic concepts introduced here can be advantageous in other cases, particularly when dealing with noisy and sparse data. The implementation is based on open-source and cross-platform software packages only, making it easy to distribute and modify. It is implemented in a microfluidic experiment allowing real-time multi-particle tracking at 70 Hz, achieving a detection rate which exceeds 94% and only 1% false-detection. PMID:26329642

  8. Robust and highly performant ring detection algorithm for 3d particle tracking using 2d microscope imaging

    NASA Astrophysics Data System (ADS)

    Afik, Eldad

    2015-09-01

    Three-dimensional particle tracking is an essential tool in studying dynamics under the microscope, namely, fluid dynamics in microfluidic devices, bacteria taxis, cellular trafficking. The 3d position can be determined using 2d imaging alone by measuring the diffraction rings generated by an out-of-focus fluorescent particle, imaged on a single camera. Here I present a ring detection algorithm exhibiting a high detection rate, which is robust to the challenges arising from ring occlusion, inclusions and overlaps, and allows resolving particles even when near to each other. It is capable of real time analysis thanks to its high performance and low memory footprint. The proposed algorithm, an offspring of the circle Hough transform, addresses the need to efficiently trace the trajectories of many particles concurrently, when their number in not necessarily fixed, by solving a classification problem, and overcomes the challenges of finding local maxima in the complex parameter space which results from ring clusters and noise. Several algorithmic concepts introduced here can be advantageous in other cases, particularly when dealing with noisy and sparse data. The implementation is based on open-source and cross-platform software packages only, making it easy to distribute and modify. It is implemented in a microfluidic experiment allowing real-time multi-particle tracking at 70 Hz, achieving a detection rate which exceeds 94% and only 1% false-detection.

  9. Robust and highly performant ring detection algorithm for 3d particle tracking using 2d microscope imaging.

    PubMed

    Afik, Eldad

    2015-01-01

    Three-dimensional particle tracking is an essential tool in studying dynamics under the microscope, namely, fluid dynamics in microfluidic devices, bacteria taxis, cellular trafficking. The 3d position can be determined using 2d imaging alone by measuring the diffraction rings generated by an out-of-focus fluorescent particle, imaged on a single camera. Here I present a ring detection algorithm exhibiting a high detection rate, which is robust to the challenges arising from ring occlusion, inclusions and overlaps, and allows resolving particles even when near to each other. It is capable of real time analysis thanks to its high performance and low memory footprint. The proposed algorithm, an offspring of the circle Hough transform, addresses the need to efficiently trace the trajectories of many particles concurrently, when their number in not necessarily fixed, by solving a classification problem, and overcomes the challenges of finding local maxima in the complex parameter space which results from ring clusters and noise. Several algorithmic concepts introduced here can be advantageous in other cases, particularly when dealing with noisy and sparse data. The implementation is based on open-source and cross-platform software packages only, making it easy to distribute and modify. It is implemented in a microfluidic experiment allowing real-time multi-particle tracking at 70 Hz, achieving a detection rate which exceeds 94% and only 1% false-detection. PMID:26329642

  10. Imaging Agonist-Induced D2/D3 Receptor Desensitization and Internalization In Vivo with PET/fMRI.

    PubMed

    Sander, Christin Y; Hooker, Jacob M; Catana, Ciprian; Rosen, Bruce R; Mandeville, Joseph B

    2016-04-01

    This study investigated the dynamics of dopamine receptor desensitization and internalization, thereby proposing a new technique for non-invasive, in vivo measurements of receptor adaptations. The D2/D3 agonist quinpirole, which induces receptor internalization in vitro, was administered at graded doses in non-human primates while imaging with simultaneous positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). A pronounced temporal divergence between receptor occupancy and fMRI signal was observed: occupancy remained elevated while fMRI responded transiently. Analogous experiments with an antagonist (prochlorperazine) and a lower-affinity agonist (ropinirole) exhibited reduced temporal dissociation between occupancy and function, consistent with a mechanism of desensitization and internalization that depends upon drug efficacy and affinity. We postulated a model that incorporates internalization into a neurovascular-coupling relationship. This model yielded in vivo desensitization/internalization rates (0.2/min for quinpirole) consistent with published in vitro measurements. Overall, these results suggest that simultaneous PET/fMRI enables characterization of dynamic neuroreceptor adaptations in vivo, and may offer a first non-invasive method for assessing receptor desensitization and internalization. PMID:26388148

  11. Development of fast patient position verification software using 2D-3D image registration and its clinical experience

    PubMed Central

    Mori, Shinichiro; Kumagai, Motoki; Miki, Kentaro; Fukuhara, Riki; Haneishi, Hideaki

    2015-01-01

    To improve treatment workflow, we developed a graphic processing unit (GPU)-based patient positional verification software application and integrated it into carbon-ion scanning beam treatment. Here, we evaluated the basic performance of the software. The algorithm provides 2D/3D registration matching using CT and orthogonal X-ray flat panel detector (FPD) images. The participants were 53 patients with tumors of the head and neck, prostate or lung receiving carbon-ion beam treatment. 2D/3D-ITchi-Gime (ITG) calculation accuracy was evaluated in terms of computation time and registration accuracy. Registration calculation was determined using the similarity measurement metrics gradient difference (GD), normalized mutual information (NMI), zero-mean normalized cross-correlation (ZNCC), and their combination. Registration accuracy was dependent on the particular metric used. Representative examples were determined to have target registration error (TRE) = 0.45 ± 0.23 mm and angular error (AE) = 0.35 ± 0.18° with ZNCC + GD for a head and neck tumor; TRE = 0.12 ± 0.07 mm and AE = 0.16 ± 0.07° with ZNCC for a pelvic tumor; and TRE = 1.19 ± 0.78 mm and AE = 0.83 ± 0.61° with ZNCC for lung tumor. Calculation time was less than 7.26 s.The new registration software has been successfully installed and implemented in our treatment process. We expect that it will improve both treatment workflow and treatment accuracy. PMID:26081313

  12. Development of fast patient position verification software using 2D-3D image registration and its clinical experience.

    PubMed

    Mori, Shinichiro; Kumagai, Motoki; Miki, Kentaro; Fukuhara, Riki; Haneishi, Hideaki

    2015-09-01

    To improve treatment workflow, we developed a graphic processing unit (GPU)-based patient positional verification software application and integrated it into carbon-ion scanning beam treatment. Here, we evaluated the basic performance of the software. The algorithm provides 2D/3D registration matching using CT and orthogonal X-ray flat panel detector (FPD) images. The participants were 53 patients with tumors of the head and neck, prostate or lung receiving carbon-ion beam treatment. 2D/3D-ITchi-Gime (ITG) calculation accuracy was evaluated in terms of computation time and registration accuracy. Registration calculation was determined using the similarity measurement metrics gradient difference (GD), normalized mutual information (NMI), zero-mean normalized cross-correlation (ZNCC), and their combination. Registration accuracy was dependent on the particular metric used. Representative examples were determined to have target registration error (TRE) = 0.45 ± 0.23 mm and angular error (AE) = 0.35 ± 0.18° with ZNCC + GD for a head and neck tumor; TRE = 0.12 ± 0.07 mm and AE = 0.16 ± 0.07° with ZNCC for a pelvic tumor; and TRE = 1.19 ± 0.78 mm and AE = 0.83 ± 0.61° with ZNCC for lung tumor. Calculation time was less than 7.26 s.The new registration software has been successfully installed and implemented in our treatment process. We expect that it will improve both treatment workflow and treatment accuracy. PMID:26081313

  13. Robust initialization of 2D-3D image registration using the projection-slice theorem and phase correlation

    SciTech Connect

    Bom, M. J. van der; Bartels, L. W.; Gounis, M. J.; Homan, R.; Timmer, J.; Viergever, M. A.; Pluim, J. P. W.

    2010-04-15

    Purpose: The image registration literature comprises many methods for 2D-3D registration for which accuracy has been established in a variety of applications. However, clinical application is limited by a small capture range. Initial offsets outside the capture range of a registration method will not converge to a successful registration. Previously reported capture ranges, defined as the 95% success range, are in the order of 4-11 mm mean target registration error. In this article, a relatively computationally inexpensive and robust estimation method is proposed with the objective to enlarge the capture range. Methods: The method uses the projection-slice theorem in combination with phase correlation in order to estimate the transform parameters, which provides an initialization of the subsequent registration procedure. Results: The feasibility of the method was evaluated by experiments using digitally reconstructed radiographs generated from in vivo 3D-RX data. With these experiments it was shown that the projection-slice theorem provides successful estimates of the rotational transform parameters for perspective projections and in case of translational offsets. The method was further tested on ex vivo ovine x-ray data. In 95% of the cases, the method yielded successful estimates for initial mean target registration errors up to 19.5 mm. Finally, the method was evaluated as an initialization method for an intensity-based 2D-3D registration method. The uninitialized and initialized registration experiments had success rates of 28.8% and 68.6%, respectively. Conclusions: The authors have shown that the initialization method based on the projection-slice theorem and phase correlation yields adequate initializations for existing registration methods, thereby substantially enlarging the capture range of these methods.

  14. An automatic 2D-3D image matching method for reproducing spatial knee joint positions using single or dual fluoroscopic images.

    PubMed

    Zhu, Zhonglin; Li, Guoan

    2012-01-01

    Fluoroscopic image technique, using either a single image or dual images, has been widely applied to measure in vivo human knee joint kinematics. However, few studies have compared the advantages of using single and dual fluoroscopic images. Furthermore, due to the size limitation of the image intensifiers, it is possible that only a portion of the knee joint could be captured by the fluoroscopy during dynamic knee joint motion. In this paper, we presented a systematic evaluation of an automatic 2D-3D image matching method in reproducing spatial knee joint positions using either single or dual fluoroscopic image techniques. The data indicated that for the femur and tibia, their spatial positions could be determined with an accuracy and precision less than 0.2 mm in translation and less than 0.4° in orientation when dual fluoroscopic images were used. Using single fluoroscopic images, the method could produce satisfactory accuracy in joint positions in the imaging plane (in average up to 0.5 mm in translation and 1.3° in rotation), but large variations along the out-plane direction (in average up to 4.0 mm in translation and 2.2° in rotation). The precision of using single fluoroscopic images to determine the actual knee positions was worse than its accuracy obtained. The data also indicated that when using dual fluoroscopic image technique, if the knee joint outlines in one image were incomplete by 80%, the algorithm could still reproduce the joint positions with high precisions. PMID:21806411

  15. Robust 3D-2D image registration: application to spine interventions and vertebral labeling in the presence of anatomical deformation

    NASA Astrophysics Data System (ADS)

    Otake, Yoshito; Wang, Adam S.; Webster Stayman, J.; Uneri, Ali; Kleinszig, Gerhard; Vogt, Sebastian; Khanna, A. Jay; Gokaslan, Ziya L.; Siewerdsen, Jeffrey H.

    2013-12-01

    We present a framework for robustly estimating registration between a 3D volume image and a 2D projection image and evaluate its precision and robustness in spine interventions for vertebral localization in the presence of anatomical deformation. The framework employs a normalized gradient information similarity metric and multi-start covariance matrix adaptation evolution strategy optimization with local-restarts, which provided improved robustness against deformation and content mismatch. The parallelized implementation allowed orders-of-magnitude acceleration in computation time and improved the robustness of registration via multi-start global optimization. Experiments involved a cadaver specimen and two CT datasets (supine and prone) and 36 C-arm fluoroscopy images acquired with the specimen in four positions (supine, prone, supine with lordosis, prone with kyphosis), three regions (thoracic, abdominal, and lumbar), and three levels of geometric magnification (1.7, 2.0, 2.4). Registration accuracy was evaluated in terms of projection distance error (PDE) between the estimated and true target points in the projection image, including 14 400 random trials (200 trials on the 72 registration scenarios) with initialization error up to ±200 mm and ±10°. The resulting median PDE was better than 0.1 mm in all cases, depending somewhat on the resolution of input CT and fluoroscopy images. The cadaver experiments illustrated the tradeoff between robustness and computation time, yielding a success rate of 99.993% in vertebral labeling (with ‘success’ defined as PDE <5 mm) using 1,718 664 ± 96 582 function evaluations computed in 54.0 ± 3.5 s on a mid-range GPU (nVidia, GeForce GTX690). Parameters yielding a faster search (e.g., fewer multi-starts) reduced robustness under conditions of large deformation and poor initialization (99.535% success for the same data registered in 13.1 s), but given good initialization (e.g., ±5 mm, assuming a robust initial run) the same registration could be solved with 99.993% success in 6.3 s. The ability to register CT to fluoroscopy in a manner robust to patient deformation could be valuable in applications such as radiation therapy, interventional radiology, and an assistant to target localization (e.g., vertebral labeling) in image-guided spine surgery.

  16. Robust 3D-2D image registration: application to spine interventions and vertebral labeling in the presence of anatomical deformation.

    PubMed

    Otake, Yoshito; Wang, Adam S; Webster Stayman, J; Uneri, Ali; Kleinszig, Gerhard; Vogt, Sebastian; Khanna, A Jay; Gokaslan, Ziya L; Siewerdsen, Jeffrey H

    2013-12-01

    We present a framework for robustly estimating registration between a 3D volume image and a 2D projection image and evaluate its precision and robustness in spine interventions for vertebral localization in the presence of anatomical deformation. The framework employs a normalized gradient information similarity metric and multi-start covariance matrix adaptation evolution strategy optimization with local-restarts, which provided improved robustness against deformation and content mismatch. The parallelized implementation allowed orders-of-magnitude acceleration in computation time and improved the robustness of registration via multi-start global optimization. Experiments involved a cadaver specimen and two CT datasets (supine and prone) and 36 C-arm fluoroscopy images acquired with the specimen in four positions (supine, prone, supine with lordosis, prone with kyphosis), three regions (thoracic, abdominal, and lumbar), and three levels of geometric magnification (1.7, 2.0, 2.4). Registration accuracy was evaluated in terms of projection distance error (PDE) between the estimated and true target points in the projection image, including 14 400 random trials (200 trials on the 72 registration scenarios) with initialization error up to ±200 mm and ±10°. The resulting median PDE was better than 0.1 mm in all cases, depending somewhat on the resolution of input CT and fluoroscopy images. The cadaver experiments illustrated the tradeoff between robustness and computation time, yielding a success rate of 99.993% in vertebral labeling (with 'success' defined as PDE <5 mm) using 1,718 664 ± 96 582 function evaluations computed in 54.0 ± 3.5 s on a mid-range GPU (nVidia, GeForce GTX690). Parameters yielding a faster search (e.g., fewer multi-starts) reduced robustness under conditions of large deformation and poor initialization (99.535% success for the same data registered in 13.1 s), but given good initialization (e.g., ±5 mm, assuming a robust initial run) the same registration could be solved with 99.993% success in 6.3 s. The ability to register CT to fluoroscopy in a manner robust to patient deformation could be valuable in applications such as radiation therapy, interventional radiology, and an assistant to target localization (e.g., vertebral labeling) in image-guided spine surgery. PMID:24246386

  17. Spectrum simulation of rough and nanostructured targets from their 2D and 3D image by Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Schiettekatte, François; Chicoine, Martin

    2016-03-01

    Corteo is a program that implements Monte Carlo (MC) method to simulate ion beam analysis (IBA) spectra of several techniques by following the ions trajectory until a sufficiently large fraction of them reach the detector to generate a spectrum. Hence, it fully accounts for effects such as multiple scattering (MS). Here, a version of Corteo is presented where the target can be a 2D or 3D image. This image can be derived from micrographs where the different compounds are identified, therefore bringing extra information into the solution of an IBA spectrum, and potentially significantly constraining the solution. The image intrinsically includes many details such as the actual surface or interfacial roughness, or actual nanostructures shape and distribution. This can for example lead to the unambiguous identification of structures stoichiometry in a layer, or at least to better constraints on their composition. Because MC computes in details the trajectory of the ions, it simulates accurately many of its aspects such as ions coming back into the target after leaving it (re-entry), as well as going through a variety of nanostructures shapes and orientations. We show how, for example, as the ions angle of incidence becomes shallower than the inclination distribution of a rough surface, this process tends to make the effective roughness smaller in a comparable 1D simulation (i.e. narrower thickness distribution in a comparable slab simulation). Also, in ordered nanostructures, target re-entry can lead to replications of a peak in a spectrum. In addition, bitmap description of the target can be used to simulate depth profiles such as those resulting from ion implantation, diffusion, and intermixing. Other improvements to Corteo include the possibility to interpolate the cross-section in angle-energy tables, and the generation of energy-depth maps.

  18. High-resolution high-sensitivity elemental imaging by secondary ion mass spectrometry: from traditional 2D and 3D imaging to correlative microscopy

    NASA Astrophysics Data System (ADS)

    Wirtz, T.; Philipp, P.; Audinot, J.-N.; Dowsett, D.; Eswara, S.

    2015-10-01

    Secondary ion mass spectrometry (SIMS) constitutes an extremely sensitive technique for imaging surfaces in 2D and 3D. Apart from its excellent sensitivity and high lateral resolution (50 nm on state-of-the-art SIMS instruments), advantages of SIMS include high dynamic range and the ability to differentiate between isotopes. This paper first reviews the underlying principles of SIMS as well as the performance and applications of 2D and 3D SIMS elemental imaging. The prospects for further improving the capabilities of SIMS imaging are discussed. The lateral resolution in SIMS imaging when using the microprobe mode is limited by (i) the ion probe size, which is dependent on the brightness of the primary ion source, the quality of the optics of the primary ion column and the electric fields in the near sample region used to extract secondary ions; (ii) the sensitivity of the analysis as a reasonable secondary ion signal, which must be detected from very tiny voxel sizes and thus from a very limited number of sputtered atoms; and (iii) the physical dimensions of the collision cascade determining the origin of the sputtered ions with respect to the impact site of the incident primary ion probe. One interesting prospect is the use of SIMS-based correlative microscopy. In this approach SIMS is combined with various high-resolution microscopy techniques, so that elemental/chemical information at the highest sensitivity can be obtained with SIMS, while excellent spatial resolution is provided by overlaying the SIMS images with high-resolution images obtained by these microscopy techniques. Examples of this approach are given by presenting in situ combinations of SIMS with transmission electron microscopy (TEM), helium ion microscopy (HIM) and scanning probe microscopy (SPM).

  19. Simulating Dynamic Stall in a 2D VAWT: Modeling strategy, verification and validation with Particle Image Velocimetry data

    NASA Astrophysics Data System (ADS)

    Simão Ferreira, C. J.; Bijl, H.; van Bussel, G.; van Kuik, G.

    2007-07-01

    The implementation of wind energy conversion systems in the built environment renewed the interest and the research on Vertical Axis Wind Turbines (VAWT), which in this application present several advantages over Horizontal Axis Wind Turbines (HAWT). The VAWT has an inherent unsteady aerodynamic behavior due to the variation of angle of attack with the angle of rotation, perceived velocity and consequentially Reynolds number. The phenomenon of dynamic stall is then an intrinsic effect of the operation of a Vertical Axis Wind Turbine at low tip speed ratios, having a significant impact in both loads and power. The complexity of the unsteady aerodynamics of the VAWT makes it extremely attractive to be analyzed using Computational Fluid Dynamics (CFD) models, where an approximation of the continuity and momentum equations of the Navier-Stokes equations set is solved. The complexity of the problem and the need for new design approaches for VAWT for the built environment has driven the authors of this work to focus the research of CFD modeling of VAWT on: •comparing the results between commonly used turbulence models: URANS (Spalart-Allmaras and k-epsilon) and large eddy models (Large Eddy Simulation and Detached Eddy Simulation) •verifying the sensitivity of the model to its grid refinement (space and time), •evaluating the suitability of using Particle Image Velocimetry (PIV) experimental data for model validation. The 2D model created represents the middle section of a single bladed VAWT with infinite aspect ratio. The model simulates the experimental work of flow field measurement using Particle Image Velocimetry by Simão Ferreira et al for a single bladed VAWT. The results show the suitability of the PIV data for the validation of the model, the need for accurate simulation of the large eddies and the sensitivity of the model to grid refinement.

  20. Watching Silica's Dance: Imaging the Structure and Dynamics of the Atomic (Re-) Arrangements in 2D Glass

    NASA Astrophysics Data System (ADS)

    Muller, David

    2014-03-01

    Even though glasses are almost ubiquitous--in our windows, on our iPhones, even on our faces--they are also mysterious. Because glasses are notoriously difficult to study, basic questions like: ``How are the atoms arranged? Where and how do glasses break?'' are still under contention. We use aberration corrected transmission electron microscopy (TEM) to image the atoms in a new two-dimensional phase of silica glass - freestanding it becomes the world's thinnest pane of glass at only 3-atoms thick, and take a unique look into these questions. Using atom-by-atom imaging and spectroscopy, we are able to reconstruct the full structure and bonding of this 2D glass and identify it as a bi-tetrahedral layer of SiO2. Our images also strikingly resemble Zachariasen's original cartoon models of glasses, drawn in 1932. As such, our work realizes an 80-year-old vision for easily understandable glassy systems and introduces promising methods to test theoretical predictions against experimental data. We image atoms in the disordered solid and track their motions in response to local strain. We directly obtain ring statistics and pair distribution functions that span short-, medium-, and long-range order, and test these against long-standing theoretical predictions of glass structure and dynamics. We use the electron beam to excite atomic rearrangements, producing surprisingly rich and beautiful videos of how a glass bends and breaks, as well as the exchange of atoms at a solid/liquid interface. Detailed analyses of these videos reveal a complex dance of elastic and plastic deformations, phase transitions, and their interplay. These examples illustrate the wide-ranging and fundamental materials physics that can now be studied at atomic-resolution via transmission electron microscopy of two-dimensional glasses. Work in collaboration with: S. Kurasch, U. Kaiser, R. Hovden, Q. Mao, J. Kotakoski, J. S. Alden, A. Shekhawat, A. A. Alemi, J. P. Sethna, P. L. McEuen, A.V. Krasheninnikov, A. Srivastava, V. Skakalova, J. C. Meyer, and J.H. Smet. This work was supported by the NSF through the Cornell Center for Materials Research (NSF DMR-1120296).

  1. Dynamics of sea-surface temperature anomalies in the Southern Ocean diagnosed from a 2D mixed-layer model

    NASA Astrophysics Data System (ADS)

    Vivier, Frédéric; Iudicone, Daniele; Busdraghi, Fabiano; Park, Young-Hyang

    2010-02-01

    We analyze the processes responsible for the generation and evolution of sea-surface temperature anomalies observed in the Southern Ocean during a decade based on a 2D diagnostic mixed-layer model in which geostrophic advection is prescribed from altimetry. Anomalous air-sea heat flux is the dominant term of the heat budget over most of the domain, while anomalous Ekman heat fluxes account for 20-40% of the variance in the latitude band 40°-60°S. In the ACC pathway, lateral fluxes of heat associated with anomalous geostrophic currents are a major contributor, dominating downstream of several topographic features, reflecting the influence of eddies and frontal migrations. A significant fraction of the variability of large-scale SST anomalies is correlated with either ENSO or the SAM, each mode contributing roughly equally. The relation between the heat budget terms and these climate modes is investigated, showing in particular that anomalous Ekman and air-sea heat fluxes have a co-operating effect (with regional exceptions), hence the large SST response associated with each mode. It is further shown that ENSO- or SAM-locked anomalous geostrophic currents generate substantial heat fluxes in all three basins with magnitude comparable with that of atmospheric forcings for ENSO, and smaller for the SAM except for limited areas. ENSO-locked forcings generate SST anomalies along the ACC pathway, and advection by mean flows is found to be a non-negligible contribution to the heat budget, exhibiting a wavenumber two zonal structure, characteristic of the Antarctic Circumpolar Wave. By contrast SAM-related forcings are predominantly zonally uniform along the ACC, hence smaller zonal SST gradients and a lesser role of mean advection, except in the SouthWest Atlantic. While modeled SST anomalies are significantly correlated with observations over most of the Southern Ocean, the analysis of the data-model discrepancies suggests that vertical ocean physics may play a significant role in the nonseasonal heat budget, especially in some key regions for mode water formation.

  2. Ground penetrating radar: 2-D and 3-D subsurface imaging of a coastal barrier spit, Long Beach, WA, USA

    NASA Astrophysics Data System (ADS)

    Jol, Harry M.; Lawton, Don C.; Smith, Derald G.

    2003-07-01

    The ability to effectively interpret and reconstruct geomorphic environments has been significantly aided by the subsurface imaging capabilities of ground penetrating radar (GPR). The GPR method, which is based on the propagation and reflection of pulsed high frequency electromagnetic energy, provides high resolution (cm to m scale) and shallow subsurface (0-60 m), near continuous profiles of many coarser-grained deposits (sediments of low electrical conductivity). This paper presents 2-D and 3-D GPR results from an experiment on a regressive modern barrier spit at Willapa Bay, WA, USA. The medium-grained sand spit is 38 km long, up to 2-3.5 km wide, and is influenced by a 3.7-m tidal range (spring) as well as high energy longshore transport and high wave energy depositional processes. The spit has a freshwater aquifer recharged by rainfall. The GPR acquisition system used for the test was a portable, digital pulseEKKO™ system with antennae frequency ranging from 25 to 200 MHz and transmitter voltages ranging from 400 to 1000 V. Step sizes and antennae separation varied depending on the test requirements. In addition, 100-MHz antennae were used for conducting antennae orientation tests and collecting a detailed grid of data (50×50 m sampled every meter). The 2-D digital profiles were processed and plotted using pulseEKKO™ software. The 3-D datasets, after initial processing, were entered into a LANDMARK™ workstation that allowed for unique 3-D perspectives of the subsurface. To provide depth, near-surface velocity measurements were calculated from common midpoint (CMP) surveys. Results from the present study demonstrate higher resolution from the 200-MHz antennae for the top 5-6 m, whereas the 25- and 50-MHz antennae show deeper penetration to >10 m. For the study site, 100-MHz antennae provided acceptable resolution, continuity of reflections, and penetration. The dip profiles show a shingle-like accretionary depositional pattern, whereas strike profiles show a horizontal and subhorizontal, nearly continuous reflection pattern. Results from the GPR experiment reveal upper shoreface reflections with dip towards the ocean at about 1-2°. The loss of signal from below a depth of 6-8 m indicates a lithofacies change because of the storm wave base. The parallel broadside and perpendicular broadside antennae orientation tests show detailed stratigraphy, continuity, and depth of penetration. The cross-polarization test exhibits reduced continuity of reflections and less depth of penetration, but dipping reflections are apparent. The grid pattern data provided a detailed view of 3-D geometry of individual reflections. High quality data were obtained, processed, and directly exported into a LANDMARK™ workstation for interpretation. The resulting interpretations of the upper shoreface beds from the test cube (50×50 m; total 2600 traces) are shown as vertical sections (slices), horizontal sections (time slices), contour maps, 3-D representations of individual beds, and an isopach map. The 3-D depositional framework allows a more detailed interpretation than widely spaced 2-D profiles.

  3. Individual Recognition in Domestic Cattle (Bos taurus): Evidence from 2D-Images of Heads from Different Breeds

    PubMed Central

    Coulon, Marjorie; Deputte, Bertrand L.; Heyman, Yvan; Baudoin, Claude

    2009-01-01

    Background In order to maintain cohesion of groups, social animals need to process social information efficiently. Visual individual recognition, which is distinguished from mere visual discrimination, has been studied in only few mammalian species. In addition, most previous studies used either a small number of subjects or a few various views as test stimuli. Dairy cattle, as a domestic species allow the testing of a good sample size and provide a large variety of test stimuli due to the morphological diversity of breeds. Hence cattle are a suitable model for studying individual visual recognition. This study demonstrates that cattle display visual individual recognition and shows the effect of both familiarity and coat diversity in discrimination. Methodology/Principal Findings We tested whether 8 Prim'Holstein heifers could recognize 2D-images of heads of one cow (face, profiles, ¾ views) from those of other cows. Experiments were based on a simultaneous discrimination paradigm through instrumental conditioning using food rewards. In Experiment 1, all images represented familiar cows (belonging to the same social group) from the Prim'Holstein breed. In Experiments 2, 3 and 4, images were from unfamiliar (unknown) individuals either from the same breed or other breeds. All heifers displayed individual recognition of familiar and unfamiliar individuals from their own breed. Subjects reached criterion sooner when recognizing a familiar individual than when recognizing an unfamiliar one (Exp 1: 3.1±0.7 vs. Exp 2: 5.2±1.2 sessions; Z = 1.99, N = 8, P = 0.046). In addition almost all subjects recognized unknown individuals from different breeds, however with greater difficulty. Conclusions/Significance Our results demonstrated that cattle have efficient individual recognition based on categorization capacities. Social familiarity improved their performance. The recognition of individuals with very different coat characteristics from the subjects was the most difficult task. These results call for studies exploring the mechanisms involved in face recognition allowing interspecies comparisons, including humans. PMID:19212439

  4. A Rapid and Efficient 2D/3D Nuclear Segmentation Method for Analysis of Early Mouse Embryo and Stem Cell Image Data

    PubMed Central

    Lou, Xinghua; Kang, Minjung; Xenopoulos, Panagiotis; Muoz-Descalzo, Silvia; Hadjantonakis, Anna-Katerina

    2014-01-01

    Summary Segmentation is a fundamental problem that dominates the success of microscopic image analysis. In almost 25 years of cell detection software development, there is still no single piece of commercial software that works well in practice when applied to early mouse embryo or stem cell image data. To address this need, we developed MINS (modular interactive nuclear segmentation) as a MATLAB/C++-based segmentation tool tailored for counting cells and fluorescent intensity measurements of 2D and 3D image data. Our aim was to develop a tool that is accurate and efficient yet straightforward and user friendly. The MINS pipeline comprises three major cascaded modules: detection, segmentation, and cell position classification. An extensive evaluation of MINS on both 2D and 3D images, and comparison to related tools, reveals improvements in segmentation accuracy and usability. Thus, its accuracy and ease of use will allow MINS to be implemented for routine single-cell-level image analyses. PMID:24672759

  5. Effects of x-ray and CT image enhancements on the robustness and accuracy of a rigid 3D/2D image registration

    SciTech Connect

    Kim, Jinkoo; Yin Fangfang; Zhao Yang; Kim, Jae Ho

    2005-04-01

    A rigid body three-dimensional/two-dimensional (3D/2D) registration method has been implemented using mutual information, gradient ascent, and 3D texturemap-based digitally reconstructed radiographs. Nine combinations of commonly used x-ray and computed tomography (CT) image enhancement methods, including window leveling, histogram equalization, and adaptive histogram equalization, were examined to assess their effects on accuracy and robustness of the registration method. From a set of experiments using an anthropomorphic chest phantom, we were able to draw several conclusions. First, the CT and x-ray preprocessing combination with the widest attraction range was the one that linearly stretched the histograms onto the entire display range on both CT and x-ray images. The average attraction ranges of this combination were 71.3 mm and 61.3 deg in the translation and rotation dimensions, respectively, and the average errors were 0.12 deg and 0.47 mm. Second, the combination of the CT image with tissue and bone information and the x-ray images with adaptive histogram equalization also showed subvoxel accuracy, especially the best in the translation dimensions. However, its attraction ranges were the smallest among the examined combinations (on average 36 mm and 19 deg). Last the bone-only information on the CT image did not show convergency property to the correct registration.

  6. 3D reconstruction of 2D fluorescence histology images and registration with in vivo MR images: application in a rodent stroke model.

    PubMed

    Stille, Maik; Smith, Edward J; Crum, William R; Modo, Michel

    2013-09-30

    To validate and add value to non-invasive imaging techniques, the corresponding histology is required to establish biological correlates. We present an efficient, semi-automated image-processing pipeline that uses immunohistochemically stained sections to reconstruct a 3D brain volume from 2D histological images before registering these with the corresponding 3D in vivo magnetic resonance images (MRI). A multistep registration procedure that first aligns the "global" volume by using the centre of mass and then applies a rigid and affine alignment based on signal intensities is described. This technique was applied to a training set of three rat brain volumes before being validated on three normal brains. Application of the approach to register "abnormal" images from a rat model of stroke allowed the neurobiological correlates of the variations in the hyper-intense MRI signal intensity caused by infarction to be investigated. For evaluation, the corresponding anatomical landmarks in MR and histology were defined to measure the registration accuracy. A registration error of 0.249 mm (approximately one in-plane voxel dimension) was evident in healthy rat brains and of 0.323 mm in a rodent model of stroke. The proposed reconstruction and registration pipeline allowed for the precise analysis of non-invasive MRI and corresponding microstructural histological features in 3D. We were thus able to interrogate histology to deduce the cause of MRI signal variations in the lesion cavity and the peri-infarct area. PMID:23816399

  7. Enhanced photomask quality control by 2D structures monitoring using auto image-to-layout method on advanced 28nm technology node or beyond

    NASA Astrophysics Data System (ADS)

    Guo, Eric; Shi, Irene; Tian, Eric; Hsiang, Chingyun; Cheng, Guojie; Ling, Li; Chen, Shijie; Chen, Ye; Zhou, Ke; Wu, Joanne; Wu, KeChih

    2013-04-01

    As device features continue to shrink, achieving acceptable yields becomes increasingly challenging. In the photolithography process, mask error is one of the most critical error sources, since any imperfections on a mask will be amplified and transferred onto a wafer due to Mask Error Enhancement Factor (MEEF) [1]. Furthermore, due to complexity of lithography optical proximity effect correction in advanced technology nodes, more and more 2D structures are applied into mask patterns. Furthermore, more 2D pattern configurations are susceptible to pattering failures due to their much high MEEF factor than 1D pattern. As a result, the conventional mask error control mechanisms for 1D [2] [3] [4] only, such as mean-to-target (MTT) and CD uniformity, are no longer adequate to deal with high MEEF 2D structures. In this paper, a novel 2D structure mask error monitoring technique is introduced to prevent fatal wafer printing errors such as CD error, line-end pull back and other pattern distortions to ensure high quality mask manufacturing and to improve wafer yield in advanced technology nodes. We will demonstrate the flow using typical 2D structure test patterns in 28nm technology node design or beyond. The SEM image would be taken and measured by this novel technique are used to monitor mask fidelity performance. This monitoring technique is based on Image-to-layout, as one of Anchor Semiconductor's pattern centric techniques, which can extract contour and convert it into pattern layouts from SEM or optical image of masks. Further pattern signature analysis can be performed on the pattern (inner /outer vertex, space distance and edge distance), so that we can quickly identify target locations for 2D pattern measurements. We monitor the severity of 2D corner rounding on selected 28nm design rule masks by Pattern Fidelity (PF) ratio and correlate them with wafer printing results. 2D pattern measurement techniques and PF ratio monitoring system from SEM image is an effective approach to ensure high quality mask making in 28nm and advanced technology nodes. This PF ratio monitoring from 2D pattern SEM images is an effective approach to ensure high quality mask making in advanced 28nm node and beyond, which can overcome the inadequacy of current 1D measurement only method, especially for the masks are generated without source mask optimization (SMO) [6].

  8. Chronicle of Bukit Bunuh for possible complex impact crater by 2-D resistivity imaging (2-DERI) with geotechnical borehole records

    NASA Astrophysics Data System (ADS)

    Jinmin, M.; Saad, R.; Saidin, M.; Ismail, N. A.

    2015-03-01

    A 2-D resistivity imaging (2-DERI) study was conducted at Bukit Bunuh, Lenggong, Perak. Archaeological Global Research Centre, Universiti Sains Malaysia shows the field evidence of shock metamorphisms (suevite breccia) and crater morphology at Bukit Bunuh. A regional 2-DERI study focusing at Bukit Bunuh to identify the features of subsurface and detail study was then executed to verify boundary of the crater with the rebound effects at Bukit Bunuh which covered approximately 132.25 km2. 2-DERI survey used resistivity equipment by ABEM SAS4000 Terrameter and ES10-64C electrode slector with pole-dipole array. The survey lines were carried out using `roll-along' technique. The data were processed and analysed using RES2DINV, Excel and Surfer software to obtain resistivity results for qualitative interpretations. Bedrock depths were digitized from section by sections obtained. 2-DERI results gives both regional and detail study shows that the study area was divided into two main zones, overburden consists of alluvium mix with boulders embedded with resistivity value of 10-800 Ωm and granitic bedrock with resistivity value of >1500 Ωm and depth 5-50 m. The low level bedrock was circulated by high level bedrock (crater rim) was formed at the same area with few spots of high level bedrock which appeared at the centre of the rim which suspected as rebound zones (R). Assimilations of 2-DERI with boreholes are successful give valid and reliable results. The results of the study indicates geophysical method are capable to retrieve evidence of meteorite impact subsurface of the studied area.

  9. Elastic image registration versus speckle tracking for 2-D myocardial motion estimation: a direct comparison in vivo.

    PubMed

    Heyde, Brecht; Jasaityte, Ruta; Barbosa, Daniel; Robesyn, Valérie; Bouchez, Stefaan; Wouters, Patrick; Maes, Frederik; Claus, Piet; D'hooge, Jan

    2013-02-01

    Despite the availability of multiple solutions for assessing myocardial strain by ultrasound, little is currently known about the relative performance of the different methods. In this study, we sought to contrast two strain estimation techniques directly (speckle tracking and elastic registration) in an in vivo setting by comparing both to a gold standard reference measurement. In five open-chest sheep instrumented with ultrasonic microcrystals, 2-D images were acquired with a GE Vivid7 ultrasound system. Radial (ε(RR)), longitudinal (ε(LL)), and circumferential strain (ε(CC)) were estimated during four inotropic stages: at rest, during esmolol and dobutamine infusion, and during acute ischemia. The correlation of the end-systolic strain values of a well-validated speckle tracking approach and an elastic registration method against sonomicrometry were comparable for ε(LL) ( r=0.70 versus r=0.61, respectively; p=0.32) and ε(CC) ( r=0.73 versus r=0.80 respectively; p=0.31). However, the elastic registration method performed considerably better for ε(RR) ( r=0.64 versus r=0.85 respectively; p=0.09). Moreover, the bias and limits of agreement with respect to the reference strain estimates were statistically significantly smaller in this direction . This could be related to regularization which is imposed during the motion estimation process as opposed to an a posteriori regularization step in the speckle tracking method. Whether one method outperforms the other in detecting dysfunctional regions remains the topic of future research. PMID:23204281

  10. Automatic localization of target vertebrae in spine surgery using fast CT-to-fluoroscopy (3D-2D) image registration

    NASA Astrophysics Data System (ADS)

    Otake, Y.; Schafer, S.; Stayman, J. W.; Zbijewski, W.; Kleinszig, G.; Graumann, R.; Khanna, A. J.; Siewerdsen, J. H.

    2012-02-01

    Localization of target vertebrae is an essential step in minimally invasive spine surgery, with conventional methods relying on "level counting" - i.e., manual counting of vertebrae under fluoroscopy starting from readily identifiable anatomy (e.g., the sacrum). The approach requires an undesirable level of radiation, time, and is prone to counting errors due to the similar appearance of vertebrae in projection images; wrong-level surgery occurs in 1 of every ~3000 cases. This paper proposes a method to automatically localize target vertebrae in x-ray projections using 3D-2D registration between preoperative CT (in which vertebrae are preoperatively labeled) and intraoperative fluoroscopy. The registration uses an intensity-based approach with a gradient-based similarity metric and the CMA-ES algorithm for optimization. Digitally reconstructed radiographs (DRRs) and a robust similarity metric are computed on GPU to accelerate the process. Evaluation in clinical CT data included 5,000 PA and LAT projections randomly perturbed to simulate human variability in setup of mobile intraoperative C-arm. The method demonstrated 100% success for PA view (projection error: 0.42mm) and 99.8% success for LAT view (projection error: 0.37mm). Initial implementation on GPU provided automatic target localization within about 3 sec, with further improvement underway via multi-GPU. The ability to automatically label vertebrae in fluoroscopy promises to streamline surgical workflow, improve patient safety, and reduce wrong-site surgeries, especially in large patients for whom manual methods are time consuming and error prone.

  11. 2D segmentation of intervertebral discs and its degree of degeneration from T2-weighted magnetic resonance images

    NASA Astrophysics Data System (ADS)

    Castro-Mateos, Isaac; Pozo, José Maria; Lazary, Aron; Frangi, Alejandro F.

    2014-03-01

    Low back pain (LBP) is a disorder suffered by a large population around the world. A key factor causing this illness is Intervertebral Disc (IVD) degeneration, whose early diagnosis could help in preventing this widespread condition. Clinicians base their diagnosis on visual inspection of 2D slices of Magnetic Resonance (MR) images, which is subject to large interobserver variability. In this work, an automatic classification method is presented, which provides the Pfirrmann degree of degeneration from a mid-sagittal MR slice. The proposed method utilizes Active Contour Models, with a new geometrical energy, to achieve an initial segmentation, which is further improved using fuzzy C-means. Then, IVDs are classified according to their degree of degeneration. This classification is attained by employing Adaboost on five specific features: the mean and the variance of the probability map of the nucleus using two different approaches and the eccentricity of the fitting ellipse to the contour of the IVD. The classification method was evaluated using a cohort of 150 intervertebral discs assessed by three experts, resulting in a mean specificity (93%) and sensitivity (83%) similar to the one provided by every expert with respect to the most voted value. The segmentation accuracy was evaluated using the Dice Similarity Index (DSI) and Root Mean Square Error (RMSE) of the point-to-contour distance. The mean DSI ± 2 standard deviation was 91:7% ±5:6%, the mean RMSE was 0:82mm and the 95 percentile was 1:36mm. These results were found accurate when compared to the state-of-the-art.

  12. 2D/3D cryo x-ray fluorescence imaging at the bionanoprobe at the advanced photon source

    NASA Astrophysics Data System (ADS)

    Chen, S.; Paunesku, T.; Yuan, Y.; Deng, J.; Jin, Q.; Hong, Y. P.; Vine, D. J.; Lai, B.; Flachenecker, C.; Hornberger, B.; Brister, K.; Jacobsen, C.; Woloschak, G. E.; Vogt, S.

    2016-01-01

    Trace elements, particularly metals, play very important roles in biological systems. Synchrotron-based hard X-ray fluorescence microscopy offers the most suitable capabilities to quantitatively study trace metals in thick biological samples, such as whole cells and tissues. In this manuscript, we have demonstrated X-ray fluorescence imaging of frozen-hydrated whole cells using the recent developed Bionanoprobe (BNP). The BNP provides spatial resolution down to 30 nm and cryogenic capabilities. Frozen-hydrated biological cells have been directly examined on a sub-cellular level at liquid nitrogen temperatures with minimal sample preparation.

  13. Temperature Dependent Equilibrium Native to Unfolded Protein Dynamics and Properties Observed with IR Absorption and 2D IR Vibrational Echo Experiments

    PubMed Central

    Chung, Jean K.; Thielges, Megan C.; Bowman, Sarah E. J.; Bren, Kara L.; Fayer, M. D.

    2011-01-01

    Dynamic and structural properties of carbonmonoxy (CO)-coordinated cytochrome c552 from Hydrogenobacter thermophilus (Ht-M61A) at different temperatures under thermal equilibrium conditions were studied with infrared absorption spectroscopy and ultrafast two dimensional infrared (2D IR) vibrational echo experiments using the heme-bound CO as the vibrational probe. Depending on the temperature, the stretching mode of CO shows two distinct bands corresponding to the native and unfolded proteins. As the temperature is increased from low temperature, a new absorption band for the unfolded protein grows in and the native band decreases in amplitude. Both the temperature dependent circular dichroism and the IR absorption area ratio RA(T), defined as the ratio of the area under the unfolded band to the sum of the areas of the native and unfolded bands, suggest a two-state transition from the native to the unfolded protein. However, it is found that the absorption spectrum of the unfolded protein increases its inhomogeneous linewidth and the center frequency shifts as the temperature is increased. The changes in linewidth and center frequency demonstrate that the unfolding does not follow simple two-state behavior. The temperature dependent 2D IR vibrational echo experiments show that the fast dynamics of the native protein are virtually temperature independent. In contrast, the fast dynamics of the unfolded protein are slower than those of the native protein, and the unfolded protein fast dynamics and at least a portion of the slower dynamics of the unfolded protein change significantly, becoming faster as the temperature is raised. The temperature dependence of the absorption spectrum and the changes in dynamics measured with the 2D IR experiments confirm that the unfolded ensemble of conformers continuously changes its nature as unfolding proceeds, in contrast to the native state, which displays a temperature independent distribution of structures. PMID:21469666

  14. Real-time intensity based 2D/3D registration using kV-MV image pairs for tumor motion tracking in image guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Furtado, H.; Steiner, E.; Stock, M.; Georg, D.; Birkfellner, W.

    2014-03-01

    Intra-fractional respiratorymotion during radiotherapy is one of themain sources of uncertainty in dose application creating the need to extend themargins of the planning target volume (PTV). Real-time tumormotion tracking by 2D/3D registration using on-board kilo-voltage (kV) imaging can lead to a reduction of the PTV. One limitation of this technique when using one projection image, is the inability to resolve motion along the imaging beam axis. We present a retrospective patient study to investigate the impact of paired portal mega-voltage (MV) and kV images, on registration accuracy. We used data from eighteen patients suffering from non small cell lung cancer undergoing regular treatment at our center. For each patient we acquired a planning CT and sequences of kV and MV images during treatment. Our evaluation consisted of comparing the accuracy of motion tracking in 6 degrees-of-freedom(DOF) using the anterior-posterior (AP) kV sequence or the sequence of kV-MV image pairs. We use graphics processing unit rendering for real-time performance. Motion along cranial-caudal direction could accurately be extracted when using only the kV sequence but in AP direction we obtained large errors. When using kV-MV pairs, the average error was reduced from 3.3 mm to 1.8 mm and the motion along AP was successfully extracted. The mean registration time was of 190+/-35ms. Our evaluation shows that using kVMV image pairs leads to improved motion extraction in 6 DOF. Therefore, this approach is suitable for accurate, real-time tumor motion tracking with a conventional LINAC.

  15. Efficient decoding of 2D structured illumination with linear phase stepping in X-ray phase contrast and dark-field imaging.

    PubMed

    Harmon, Katherine J; Bennett, Eric E; Gomella, Andrew A; Wen, Han

    2014-01-01

    The ability to map the phase distribution and lateral coherence of an x-ray wavefront offers the potential for imaging the human body through phase contrast, without the need to deposit significant radiation energy. The classic means to achieve this goal is structured illumination, in which a periodic intensity modulation is introduced into the image, and changes in the phase distribution of the wavefront are detected as distortions of the modulation pattern. Two-dimensional periodic patterns are needed to fully characterize a transverse wavefront. Traditionally, the information in a 2D pattern is retrieved at high resolution by acquiring multiple images while shifting the pattern over a 2D matrix of positions. Here we describe a method to decode 2D periodic patterns with single-axis phase stepping, without either a loss of information or increasing the number of sampling steps. The method is created to reduce the instrumentation complexity of high-resolution 2D wavefront sensing in general. It is demonstrated with motionless electromagnetic phase stepping and a flexible processing algorithm in x-ray dark-field and phase contrast imaging. PMID:24489853

  16. Efficient Decoding of 2D Structured Illumination with Linear Phase Stepping in X-Ray Phase Contrast and Dark-Field Imaging

    PubMed Central

    Harmon, Katherine J.; Bennett, Eric E.; Gomella, Andrew A.; Wen, Han

    2014-01-01

    The ability to map the phase distribution and lateral coherence of an x-ray wavefront offers the potential for imaging the human body through phase contrast, without the need to deposit significant radiation energy. The classic means to achieve this goal is structured illumination, in which a periodic intensity modulation is introduced into the image, and changes in the phase distribution of the wavefront are detected as distortions of the modulation pattern. Two-dimensional periodic patterns are needed to fully characterize a transverse wavefront. Traditionally, the information in a 2D pattern is retrieved at high resolution by acquiring multiple images while shifting the pattern over a 2D matrix of positions. Here we describe a method to decode 2D periodic patterns with single-axis phase stepping, without either a loss of information or increasing the number of sampling steps. The method is created to reduce the instrumentation complexity of high-resolution 2D wavefront sensing in general. It is demonstrated with motionless electromagnetic phase stepping and a flexible processing algorithm in x-ray dark-field and phase contrast imaging. PMID:24489853

  17. Validity of computational hemodynamics in human arteries based on 3D time-of-flight MR angiography and 2D electrocardiogram gated phase contrast images

    NASA Astrophysics Data System (ADS)

    Yu, Huidan (Whitney); Chen, Xi; Chen, Rou; Wang, Zhiqiang; Lin, Chen; Kralik, Stephen; Zhao, Ye

    2015-11-01

    In this work, we demonstrate the validity of 4-D patient-specific computational hemodynamics (PSCH) based on 3-D time-of-flight (TOF) MR angiography (MRA) and 2-D electrocardiogram (ECG) gated phase contrast (PC) images. The mesoscale lattice Boltzmann method (LBM) is employed to segment morphological arterial geometry from TOF MRA, to extract velocity profiles from ECG PC images, and to simulate fluid dynamics on a unified GPU accelerated computational platform. Two healthy volunteers are recruited to participate in the study. For each volunteer, a 3-D high resolution TOF MRA image and 10 2-D ECG gated PC images are acquired to provide the morphological geometry and the time-varying flow velocity profiles for necessary inputs of the PSCH. Validation results will be presented through comparisons of LBM vs. 4D Flow Software for flow rates and LBM simulation vs. MRA measurement for blood flow velocity maps. Indiana University Health (IUH) Values Fund.

  18. 2-D gel densitometer for high-contrast and selective imaging of chlorophyll-containing protein complexes separated by non-denaturing polyacrylamide gel electrophoresis.

    PubMed

    Ilík, Petr; Krchnák, Pavel; Tomek, Pavel; Naus, Jan

    2002-05-31

    In this work, we present a home-made two-dimensional (2-D) CCD imaging system for the monochromatic densitometry of plane gels and its application to the imaging and densitometry of chlorophyll (Chl)-containing proteins separated by non-denaturing polyacrylamide gel electrophoresis. The monochromatic imaging of separated green bands at the wavelengths corresponding to their absorption band increases their contrast. This allows a better visualization of the faint-green bands in the gel and using of samples with lower Chl content for the electrophoresis. By the comparison of 2-D densitograms of the same gel illuminated with 670 and 650 nm lights, that is, at the red absorption maximum of Chl a and b, respectively, we achieved a selective imaging of the complexes with different Chl a/b ratio. This approach was used to specify an unknown band that appeared in the gel of the sample prepared from the thylakoid membranes of preheated barley leaves. PMID:12088887

  19. Position tracking of moving liver lesion based on real-time registration between 2D ultrasound and 3D preoperative images

    SciTech Connect

    Weon, Chijun; Hyun Nam, Woo; Lee, Duhgoon; Ra, Jong Beom; Lee, Jae Young

    2015-01-15

    Purpose: Registration between 2D ultrasound (US) and 3D preoperative magnetic resonance (MR) (or computed tomography, CT) images has been studied recently for US-guided intervention. However, the existing techniques have some limits, either in the registration speed or the performance. The purpose of this work is to develop a real-time and fully automatic registration system between two intermodal images of the liver, and subsequently an indirect lesion positioning/tracking algorithm based on the registration result, for image-guided interventions. Methods: The proposed position tracking system consists of three stages. In the preoperative stage, the authors acquire several 3D preoperative MR (or CT) images at different respiratory phases. Based on the transformations obtained from nonrigid registration of the acquired 3D images, they then generate a 4D preoperative image along the respiratory phase. In the intraoperative preparatory stage, they properly attach a 3D US transducer to the patient’s body and fix its pose using a holding mechanism. They then acquire a couple of respiratory-controlled 3D US images. Via the rigid registration of these US images to the 3D preoperative images in the 4D image, the pose information of the fixed-pose 3D US transducer is determined with respect to the preoperative image coordinates. As feature(s) to use for the rigid registration, they may choose either internal liver vessels or the inferior vena cava. Since the latter is especially useful in patients with a diffuse liver disease, the authors newly propose using it. In the intraoperative real-time stage, they acquire 2D US images in real-time from the fixed-pose transducer. For each US image, they select candidates for its corresponding 2D preoperative slice from the 4D preoperative MR (or CT) image, based on the predetermined pose information of the transducer. The correct corresponding image is then found among those candidates via real-time 2D registration based on a gradient-based similarity measure. Finally, if needed, they obtain the position information of the liver lesion using the 3D preoperative image to which the registered 2D preoperative slice belongs. Results: The proposed method was applied to 23 clinical datasets and quantitative evaluations were conducted. With the exception of one clinical dataset that included US images of extremely low quality, 22 datasets of various liver status were successfully applied in the evaluation. Experimental results showed that the registration error between the anatomical features of US and preoperative MR images is less than 3 mm on average. The lesion tracking error was also found to be less than 5 mm at maximum. Conclusions: A new system has been proposed for real-time registration between 2D US and successive multiple 3D preoperative MR/CT images of the liver and was applied for indirect lesion tracking for image-guided intervention. The system is fully automatic and robust even with images that had low quality due to patient status. Through visual examinations and quantitative evaluations, it was verified that the proposed system can provide high lesion tracking accuracy as well as high registration accuracy, at performance levels which were acceptable for various clinical applications.

  20. Faraday imaging at high temperatures

    DOEpatents

    Hackel, L.A.; Reichert, P.

    1997-03-18

    A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid. 3 figs.

  1. Faraday imaging at high temperatures

    DOEpatents

    Hackel, Lloyd A.; Reichert, Patrick

    1997-01-01

    A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid.

  2. Study of center-bias in the viewing of stereoscopic image and a framework for extending 2D visual attention models to 3D

    NASA Astrophysics Data System (ADS)

    Wang, Junle; Perreira Da Silva, Matthieu; Le Callet, Patrick; Ricordel, Vincent

    2013-03-01

    Compared to the good performance that can be achieved by many 2D visual attention models, predicting salient regions of a 3D scene is still challenging. An efficient way to achieve this can be to exploit existing models designed for 2D content. However, the visual conflicts caused by binocular disparity and changes of viewing behavior in 3D viewing need to be dealt with. To cope with these, the present paper proposes a simple framework for extending 2D attention models for 3D images, well as evaluates center-bias in 3D-viewing condition. To validate the results, a database is created, which contains eye-movements of 35 subjects recorded during free viewing of eighteen 3D images and their corresponding 2D version. Fixation density maps indicate a weaker center-bias in the viewing of 3D images. Moreover, objective metric results demonstrate the efficiency of the proposed model and a large added value of center-bias when it is taken into account in computational modeling of 3D visual attention.

  3. MTF characterization in 2D and 3D for a high resolution, large field of view flat panel imager for cone beam CT

    NASA Astrophysics Data System (ADS)

    Shah, Jainil; Mann, Steve D.; Tornai, Martin P.; Richmond, Michelle; Zentai, George

    2014-03-01

    The 2D and 3D modulation transfer functions (MTFs) of a custom made, large 40x30cm2 area, 600- micron CsI-TFT based flat panel imager having 127-micron pixellation, along with the micro-fiber scintillator structure, were characterized in detail using various techniques. The larger area detector yields a reconstructed FOV of 25cm diameter with an 80cm SID in CT mode. The MTFs were determined with 1x1 (intrinsic) binning. The 2D MTFs were determined using a 50.8 micron tungsten wire and a solid lead edge, and the 3D MTF was measured using a custom made phantom consisting of three nearly orthogonal 50.8 micron tungsten wires suspended in an acrylic cubic frame. The 2D projection data was reconstructed using an iterative OSC algorithm using 16 subsets and 5 iterations. As additional verification of the resolution, along with scatter, the Catphan® phantom was also imaged and reconstructed with identical parameters. The measured 2D MTF was ~4% using the wire technique and ~1% using the edge technique at the 3.94 lp/mm Nyquist cut-off frequency. The average 3D MTF measured along the wires was ~8% at the Nyquist. At 50% MTF, the resolutions were 1.2 and 2.1 lp/mm in 2D and 3D, respectively. In the Catphan® phantom, the 1.7 lp/mm bars were easily observed. Lastly, the 3D MTF measured on the three wires has an observed 5.9% RMSD, indicating that the resolution of the imaging system is uniform and spatially independent. This high performance detector is integrated into a dedicated breast SPECT-CT imaging system.

  4. Significant acceleration of 2D-3D registration-based fusion of ultrasound and x-ray images by mesh-based DRR rendering

    NASA Astrophysics Data System (ADS)

    Kaiser, Markus; John, Matthias; Borsdorf, Anja; Mountney, Peter; Ionasec, Razvan; Nöttling, Alois; Kiefer, Philipp; Seeburger, Jörg; Neumuth, Thomas

    2013-03-01

    For transcatheter-based minimally invasive procedures in structural heart disease ultrasound and X-ray are the two enabling imaging modalities. A live fusion of both real-time modalities can potentially improve the workflow and the catheter navigation by combining the excellent instrument imaging of X-ray with the high-quality soft tissue imaging of ultrasound. A recently published approach to fuse X-ray fluoroscopy with trans-esophageal echo (TEE) registers the ultrasound probe to X-ray images by a 2D-3D registration method which inherently provides a registration of ultrasound images to X-ray images. In this paper, we significantly accelerate the 2D-3D registration method in this context. The main novelty is to generate the projection images (DRR) of the 3D object not via volume ray-casting but instead via a fast rendering of triangular meshes. This is possible, because in the setting for TEE/X-ray fusion the 3D geometry of the ultrasound probe is known in advance and their main components can be described by triangular meshes. We show that the new approach can achieve a speedup factor up to 65 and does not affect the registration accuracy when used in conjunction with the gradient correlation similarity measure. The improvement is independent of the underlying registration optimizer. Based on the results, a TEE/X-ray fusion could be performed with a higher frame rate and a shorter time lag towards real-time registration performance. The approach could potentially accelerate other applications of 2D-3D registrations, e.g. the registration of implant models with X-ray images.

  5. A computerized framework for monitoring four-dimensional dose distributions during stereotactic body radiation therapy using a portal dose image-based 2D/3D registration approach.

    PubMed

    Nakamoto, Takahiro; Arimura, Hidetaka; Nakamura, Katsumasa; Shioyama, Yoshiyuki; Mizoguchi, Asumi; Hirose, Taka-Aki; Honda, Hiroshi; Umezu, Yoshiyuki; Nakamura, Yasuhiko; Hirata, Hideki

    2015-03-01

    A computerized framework for monitoring four-dimensional (4D) dose distributions during stereotactic body radiation therapy based on a portal dose image (PDI)-based 2D/3D registration approach has been proposed in this study. Using the PDI-based registration approach, simulated 4D "treatment" CT images were derived from the deformation of 3D planning CT images so that a 2D planning PDI could be similar to a 2D dynamic clinical PDI at a breathing phase. The planning PDI was calculated by applying a dose calculation algorithm (a pencil beam convolution algorithm) to the geometry of the planning CT image and a virtual water equivalent phantom. The dynamic clinical PDIs were estimated from electronic portal imaging device (EPID) dynamic images including breathing phase data obtained during a treatment. The parameters of the affine transformation matrix were optimized based on an objective function and a gamma pass rate using a Levenberg-Marquardt (LM) algorithm. The proposed framework was applied to the EPID dynamic images of ten lung cancer patients, which included 183 frames (mean: 18.3 per patient). The 4D dose distributions during the treatment time were successfully obtained by applying the dose calculation algorithm to the simulated 4D "treatment" CT images. The mean±standard deviation (SD) of the percentage errors between the prescribed dose and the estimated dose at an isocenter for all cases was 3.25±4.43%. The maximum error for the ten cases was 14.67% (prescribed dose: 1.50Gy, estimated dose: 1.72Gy), and the minimum error was 0.00%. The proposed framework could be feasible for monitoring the 4D dose distribution and dose errors within a patient's body during treatment. PMID:25592290

  6. Textural analyses of carbon fiber materials by 2D-FFT of complex images obtained by high frequency eddy current imaging (HF-ECI)

    NASA Astrophysics Data System (ADS)

    Schulze, Martin H.; Heuer, Henning

    2012-04-01

    Carbon fiber based materials are used in many lightweight applications in aeronautical, automotive, machine and civil engineering application. By the increasing automation in the production process of CFRP laminates a manual optical inspection of each resin transfer molding (RTM) layer is not practicable. Due to the limitation to surface inspection, the quality parameters of multilayer 3 dimensional materials cannot be observed by optical systems. The Imaging Eddy- Current (EC) NDT is the only suitable inspection method for non-resin materials in the textile state that allows an inspection of surface and hidden layers in parallel. The HF-ECI method has the capability to measure layer displacements (misaligned angle orientations) and gap sizes in a multilayer carbon fiber structure. EC technique uses the variation of the electrical conductivity of carbon based materials to obtain material properties. Beside the determination of textural parameters like layer orientation and gap sizes between rovings, the detection of foreign polymer particles, fuzzy balls or visualization of undulations can be done by the method. For all of these typical parameters an imaging classification process chain based on a high resolving directional ECimaging device named EddyCus® MPECS and a 2D-FFT with adapted preprocessing algorithms are developed.

  7. Off-axis electron holography with a dual-lens imaging system and its usefulness in 2-D potential mapping of semiconductor devices.

    PubMed

    Wang, Y Y; Kawasaki, M; Bruley, J; Gribelyuk, M; Domenicucci, A; Gaudiello, J

    2004-11-01

    A variable magnification electron holography, applicable for two-dimensional (2-D) potential mapping of semiconductor devices, employing a dual-lens imaging system is described. Imaging operation consists of a virtual image formed by the objective lens (OL) and a real image formed in a fixed imaging plane by the objective minilens. Wide variations in field of view (100-900 nm) and fringe spacing (0.7-6 nm) were obtained using a fixed biprism voltage by varying the total magnification of the dual OL system. The dual-lens system allows fringe width and spacing relative to the object to be varied roughly independently from the fringe contrast, resulting in enhanced resolution and sensitivity. The achievable fringe width and spacing cover the targets needed for devices in the semiconductor technology road map from the 350 to 45 nm node. Two-D potential maps for CMOS devices with 220 and 70 nm gate lengths were obtained. PMID:15450653

  8. A neural network-based 2D/3D image registration quality evaluator for pediatric patient setup in external beam radiotherapy.

    PubMed

    Wu, Jian; Su, Zhong; Li, Zuofeng

    2016-01-01

    Our purpose was to develop a neural network-based registration quality evaluator (RQE) that can improve the 2D/3D image registration robustness for pediatric patient setup in external beam radiotherapy. Orthogonal daily setup X-ray images of six pediatric patients with brain tumors receiving proton therapy treatments were retrospectively registered with their treatment planning computed tomography (CT) images. A neural network-based pattern classifier was used to determine whether a registration solution was successful based on geometric features of the similarity measure values near the point-of-solution. Supervised training and test datasets were generated by rigidly registering a pair of orthogonal daily setup X-ray images to the treatment planning CT. The best solution for each registration task was selected from 50 optimizing attempts that differed only by the randomly generated initial transformation parameters. The distance from each individual solution to the best solution in the normalized parametrical space was compared to a user-defined error tolerance to determine whether that solution was acceptable. A supervised training was then used to train the RQE. Performance of the RQE was evaluated using test dataset consisting of registration results that were not used in training. The RQE was integrated with our in-house 2D/3D registration system and its performance was evaluated using the same patient dataset. With an optimized sampling step size (i.e., 5 mm) in the feature space, the RQE has the sensitivity and the speci-ficity in the ranges of 0.865-0.964 and 0.797-0.990, respectively, when used to detect registration error with mean voxel displacement (MVD) greater than 1 mm. The trial-to-acceptance ratio of the integrated 2D/3D registration system, for all patients, is equal to 1.48. The final acceptance ratio is 92.4%. The proposed RQE can potentially be used in a 2D/3D rigid image registration system to improve the overall robustness by rejecting unsuccessful registration solutions. The RQE is not patient-specific, so a single RQE can be constructed and used for a particular application (e.g., the registration for images acquired on the same anatomical site). Implementation of the RQE in a 2D/3D registration system is clinically feasible. PMID:26894329

  9. Analytic modeling of temperature dependence of 2D carrier mobility in as-grown and annealed GaInNAs/GaAs quantum well structures

    NASA Astrophysics Data System (ADS)

    Donmez, O.; Sarcan, F.; Lisesivdin, S. B.; Vaughan, M. P.; Erol, A.; Gunes, M.; Arikan, M. C.; Puustinen, J.; Guina, M.

    2014-12-01

    Temperature and nitrogen dependence of 2D carrier mobility in as-grown and annealed Ga1-xInxNyAs1-y/GaAs quantum well (QW) structures (x = 0.32 y = 0, 0.009, and 0.012) are investigated. An analytical model that accounts for the most prominent scattering mechanisms is used to explain the characteristic of temperature dependence of the carrier mobility. An expression for alloy scattering-limited mobility in N-related alloys is developed to explain the behavior of hole mobility for N-containing p-type samples. Analytical modeling of temperature dependence of the electron mobility indicates that N-related alloy scattering and interface roughness scattering are the dominant mechanism at the entire temperature range of interest. The temperature insensitivity of the electron mobility is explained in terms of the overriding effect of N-related alloy scattering and high 2D electron density. A deviation between theoretical and experimental electron mobility at low temperatures is observed not to have any dependency on N concentration. We, therefore, suggest that CNM interaction parameter of the band anti-crossing (BAC) model must be defined as temperature dependent in order to explain the observed low temperature characteristics of electron mobility. The hole mobility is mainly restricted by interface roughness and alloy scatterings at temperatures lower than 100 K, whilst high temperature hole mobility is drastically affected from optical phonon scattering. Moreover, the hole mobility at high temperatures exhibits an N-independent characteristic and hole density starts to increase at temperatures above 70 K, which is explained using the concept of parallel conduction. Extraction of the hole density in each transport channel (QW and barrier) by using a simple parallel conduction extraction method (SPCEM) shows that, in p-type samples, low temperature hole mobility takes place in quantum well, while as temperature increases barrier channel also contribute to the hole mobility and becomes dominant at high temperatures. The experimental and calculated Hall mobility results reveal that thermal annealing has decreased interface roughness and alloy scatterings.

  10. Development of code for 2-D distribution temperature transient analysis of asymmetric element linier using finite element method

    NASA Astrophysics Data System (ADS)

    Saragi, Elfrida

    2014-09-01

    Transient of temperature distribution is found in many physical and engineering events that affect the state of the end of a process. Transient state in the form of geometry and complex boundary conditions is generally difficult to be solved analytically and can only be solved by a computer code. This study is aimed to develop a software code using the finite element method for the analysis of temperature transient distribution with the form of field element discretization asymmetric linier. The completion of the temperature distribution in the transient state is essential following the same procedure on the conditions of temperature distribution at steady state. The main difference is the load at which the load transient analysis is a function of time. Resolution process using finite element method (FEM) involves three stages, namely: the provision of data (preprocessor), problem solving (processor/ solver), interpretation of the results in the form of graphs and contour (postprocessor). Stages of the software development process start from the preprocessor program as making patterns/geometric shapes to be analyzed, discretized field with shape of element asymmetric, writing the number of nodes and elements, loads, initial conditions and boundary conditions. The process of the program code includes completing the matrix stiffness coefficient (K), and matrix load (a) time-based, or called the discretization time. The completion of time discretization uses the Galerkin Method. The stiffness of coefficient consists of stiffness geometry, capacitance matrices, or matrix moisture and the burden imposed as transient loads, such as heat flux load boundary, centralized heat load of boundary, and the initial temperature. In this way the expected completion of temperature transient distribution can be done more easily, quickly, and inexpensively. The code is written using Visual Basic.

  11. Synchronized 2D/3D optical mapping for interactive exploration and real-time visualization of multi-function neurological images.

    PubMed

    Zhang, Qi; Alexander, Murray; Ryner, Lawrence

    2013-01-01

    Efficient software with the ability to display multiple neurological image datasets simultaneously with full real-time interactivity is critical for brain disease diagnosis and image-guided planning. In this paper, we describe the creation and function of a new comprehensive software platform that integrates novel algorithms and functions for multiple medical image visualization, processing, and manipulation. We implement an opacity-adjustment algorithm to build 2D lookup tables for multiple slice image display and fusion, which achieves a better visual result than those of using VTK-based methods. We also develop a new real-time 2D and 3D data synchronization scheme for multi-function MR volume and slice image optical mapping and rendering simultaneously through using the same adjustment operation. All these methodologies are integrated into our software framework to provide users with an efficient tool for flexibly, intuitively, and rapidly exploring and analyzing the functional and anatomical MR neurological data. Finally, we validate our new techniques and software platform with visual analysis and task-specific user studies. PMID:23968722

  12. Block-based spatial prediction and transforms based on 2D Markov processes for image and video compression.

    PubMed

    Kamisli, Fatih

    2015-04-01

    Conventional intraframe coding is performed in two steps. First, a block of pixels are predicted by copying previously reconstructed neighbor pixels of the block along an angular direction inside the block. Then, the prediction residual block is transform coded with the well-known 2D discrete cosine transform (DCT). Recently, it has been shown that transforming the intraprediction residuals with the odd type-3 discrete sine transform along the prediction direction and the DCT along the perpendicular direction improves the compression performance. More recently, a recursive prediction approach has been proposed to improve intra prediction performance. Both of these recent approaches utilize Markov processes to develop improvements in either the transform or the prediction step but not in both. In this paper, both the intraprediction and the transform steps are obtained based on 2D Markov processes. The derived overall intraframe coding approaches can generalize the mentioned two approaches, provide improved coding gains and produce less blocking effects at low bitrates. PMID:25675456

  13. Rapid fusion of 2D X-ray fluoroscopy with 3D multislice CT for image-guided electrophysiology procedures

    NASA Astrophysics Data System (ADS)

    Zagorchev, Lyubomir; Manzke, Robert; Cury, Ricardo; Reddy, Vivek Y.; Chan, Raymond C.

    2007-03-01

    Interventional cardiac electrophysiology (EP) procedures are typically performed under X-ray fluoroscopy for visualizing catheters and EP devices relative to other highly-attenuating structures such as the thoracic spine and ribs. These projections do not however contain information about soft-tissue anatomy and there is a recognized need for fusion of conventional fluoroscopy with pre-operatively acquired cardiac multislice computed tomography (MSCT) volumes. Rapid 2D-3D integration in this application would allow for real-time visualization of all catheters present within the thorax in relation to the cardiovascular anatomy visible in MSCT. We present a method for rapid fusion of 2D X-ray fluoroscopy with 3DMSCT that can facilitate EP mapping and interventional procedures by reducing the need for intra-operative contrast injections to visualize heart chambers and specialized systems to track catheters within the cardiovascular anatomy. We use hardware-accelerated ray-casting to compute digitally reconstructed radiographs (DRRs) from the MSCT volume and iteratively optimize the rigid-body pose of the volumetric data to maximize the similarity between the MSCT-derived DRR and the intra-operative X-ray projection data.

  14. A robust cell counting approach based on a normalized 2D cross-correlation scheme for in-line holographic images.

    PubMed

    Ra, Ho-Kyeong; Kim, Hyungseok; Yoon, Hee Jung; Son, Sang Hyuk; Park, Taejoon; Moon, Sangjun

    2013-09-01

    To achieve the important aims of identifying and marking disease progression, cell counting is crucial for various biological and medical procedures, especially in a Point-Of-Care (POC) setting. In contrast to the conventional manual method of counting cells, a software-based approach provides improved reliability, faster speeds, and greater ease of use. We present a novel software-based approach to count in-line holographic cell images using the calculation of a normalized 2D cross-correlation. This enables fast, computationally-efficient pattern matching between a set of cell library images and the test image. Our evaluation results show that the proposed system is capable of quickly counting cells whilst reliably and accurately following human counting capability. Our novel approach is 5760 times faster than manual counting and provides at least 68% improved accuracy compared to other image processing algorithms. PMID:23839256

  15. Effects of Precipitation on Ocean Mixed-Layer Temperature and Salinity as Simulated in a 2-D Coupled Ocean-Cloud Resolving Atmosphere Model

    NASA Technical Reports Server (NTRS)

    Li, Xiaofan; Sui, C.-H.; Lau, K-M.; Adamec, D.

    1999-01-01

    A two-dimensional coupled ocean-cloud resolving atmosphere model is used to investigate possible roles of convective scale ocean disturbances induced by atmospheric precipitation on ocean mixed-layer heat and salt budgets. The model couples a cloud resolving model with an embedded mixed layer-ocean circulation model. Five experiment are performed under imposed large-scale atmospheric forcing in terms of vertical velocity derived from the TOGA COARE observations during a selected seven-day period. The dominant variability of mixed-layer temperature and salinity are simulated by the coupled model with imposed large-scale forcing. The mixed-layer temperatures in the coupled experiments with 1-D and 2-D ocean models show similar variations when salinity effects are not included. When salinity effects are included, however, differences in the domain-mean mixed-layer salinity and temperature between coupled experiments with 1-D and 2-D ocean models could be as large as 0.3 PSU and 0.4 C respectively. Without fresh water effects, the nocturnal heat loss over ocean surface causes deep mixed layers and weak cooling rates so that the nocturnal mixed-layer temperatures tend to be horizontally-uniform. The fresh water flux, however, causes shallow mixed layers over convective areas while the nocturnal heat loss causes deep mixed layer over convection-free areas so that the mixed-layer temperatures have large horizontal fluctuations. Furthermore, fresh water flux exhibits larger spatial fluctuations than surface heat flux because heavy rainfall occurs over convective areas embedded in broad non-convective or clear areas, whereas diurnal signals over whole model areas yield high spatial correlation of surface heat flux. As a result, mixed-layer salinities contribute more to the density differences than do mixed-layer temperatures.

  16. A flexible and robust approach for segmenting cell nuclei from 2D microscopy images using supervised learning and template matching

    PubMed Central

    Chen, Cheng; Wang, Wei; Ozolek, John A.; Rohde, Gustavo K.

    2013-01-01

    We describe a new supervised learning-based template matching approach for segmenting cell nuclei from microscopy images. The method uses examples selected by a user for building a statistical model which captures the texture and shape variations of the nuclear structures from a given dataset to be segmented. Segmentation of subsequent, unlabeled, images is then performed by finding the model instance that best matches (in the normalized cross correlation sense) local neighborhood in the input image. We demonstrate the application of our method to segmenting nuclei from a variety of imaging modalities, and quantitatively compare our results to several other methods. Quantitative results using both simulated and real image data show that, while certain methods may work well for certain imaging modalities, our software is able to obtain high accuracy across several imaging modalities studied. Results also demonstrate that, relative to several existing methods, the template-based method we propose presents increased robustness in the sense of better handling variations in illumination, variations in texture from different imaging modalities, providing more smooth and accurate segmentation borders, as well as handling better cluttered nuclei. PMID:23568787

  17. a Circleless "2D/3D Total STATION": a Low Cost Instrument for Surveying, Recording Point Clouds, Documentation, Image Acquisition and Visualisation

    NASA Astrophysics Data System (ADS)

    Scherer, M.

    2013-07-01

    Hardware and software of the universally applicable instrument - referred to as a 2D/3D total station - are described here, as well as its practical use. At its core it consists of a 3D camera - often also called a ToF camera, a pmd camera or a RIM-camera - combined with a common industrial 2D camera. The cameras are rigidly coupled with their optical axes in parallel. A new type of instrument was created mounting this 2D/3D system on a tripod in a specific way. Because of it sharing certain characteristics with a total station and a tacheometer, respectively, the new device was called a 2D/3D total station. It may effectively replace a common total station or a laser scanner in some respects. After a brief overview of the prototype's features this paper then focuses on the methodological characteristics for practical application. Its usability as a universally applicable stand-alone instrument is demonstrated for surveying, recording RGB-coloured point clouds as well as delivering images for documentation and visualisation. Because of its limited range (10m without reflector and 150 m to reflector prisms) and low range accuracy (ca. 2 cm to 3 cm) compared to present-day total stations and laser scanners, the practical usage of the 2D/3D total station is currently limited to acquisition of accidents, forensic purpuses, speleology or facility management, as well as architectural recordings with low requirements regarding accuracy. However, the author is convinced that in the near future advancements in 3D camera technology will allow this type of comparatively low cost instrument to replace the total station as well as the laser scanner in an increasing number of areas.

  18. In-111 chimeric negative-charged-Z2D3 PL-F(ab`){sub 2} imaging of proliferating smooth muscle cell in atherosclerotic lesions

    SciTech Connect

    Carrio, I.; Pieri, P.L.; Narula, J.

    1996-05-01

    Metabolically active plaques have proliferating smooth muscle cells. In-111-labeled negative-charged modified Z2-D3 PL-F(ab`){sub 2} (NC-Z2D3) specific for an antigen in proliferating smooth muscle cells has been shown to accumulate in rabbit atherosclerotic plaques. The safety, biodistribution and accumulation of NC-Z2D3 were assessed in 11 patients with angiographically confirmed carotid atheromas eligible for endarterectomy. NC-Z2D3 (250 mcg) labeled with 5 mCi of In-11 was administered by slow i.v. inj.. Planar and SPECT images were obtained 4, 24, 48 and 72 hrs later. Endarterectomy was then performed and the specimens were analyzed. Focal uptake of In-111-NCZ2D3 at the site of the carotid plaques was seen at 4 hrs. Target to control ratio at 4 hrs was 2.20 {plus_minus} 0.3, 1.98 {plus_minus} 0.03 at 24 hrs, 1.60 {plus_minus} 0.2 at 48 hrs and 1.45 {plus_minus} 0.2 at 72 hrs. The pattern of uptake was frequently more extended than the stenotic regions as delineated by the angiograms. Avidin-Biotin-Peroxidase immunostaining of the specimens revealed staining of proliferating smooth muscle cells at the site of the plaque. Percent of the injected dose per gram localization in the specimens was 0.0475 {plus_minus} 0.007. Blood clearance followed a biexponential curve with a mean t{1/2} of 920 minutes. Nonspecific localization of the antibody was observed in the liver, bone-marrow and kidneys. Adverse reactions were not seen. This study demonstrates the feasibility of targeting active atherosclerotic lesions with negatively charge-modified antibody.

  19. A comparison of the 3D kinematic measurements obtained by single-plane 2D-3D image registration and RSA.

    PubMed

    Muhit, Abdullah A; Pickering, Mark R; Ward, Tom; Scarvell, Jennie M; Smith, Paul N

    2010-01-01

    3D computed tomography (CT) to single-plane 2D fluoroscopy registration is an emerging technology for many clinical applications such as kinematic analysis of human joints and image-guided surgery. However, previous registration approaches have suffered from the inaccuracy of determining precise motion parameters for out-of-plane movements. In this paper we compare kinematic measurements obtained by a new 2D-3D registration algorithm with measurements provided by the gold standard Roentgen Stereo Analysis (RSA). In particular, we are interested in the out-of-plane translation and rotations which are difficult to measure precisely using a single plane approach. Our experimental results show that the standard deviation of the error for out-of-plane translation is 0.42 mm which compares favourably to RSA. It is also evident that our approach produces very similar flexion/extension, abduction/adduction and external knee rotation angles when compared to RSA. PMID:21097358

  20. Magnetic resonance tomography using elongated transmitter and in-loop receiver arrays for time-efficient 2-D imaging of subsurface aquifer structures

    NASA Astrophysics Data System (ADS)

    Jiang, C.; Müller-Petke, M.; Lin, J.; Yaramanci, U.

    2015-02-01

    Surface nuclear magnetic resonance (surface-NMR) is a promising technique for exploring shallow subsurface aquifer structures. Surface-NMR can be applied in environments that are characterized as a 1-D layered Earth. The technique utilizes a single loop and is referred to as magnetic resonance sounding. The technique referred to as magnetic resonance tomography (MRT) allows complex 2-D aquifer structures to be explored. Currently, MRT requires multiple loops and a roll along measurement scheme, which causes long survey time. We propose a loop layout using an elongated transmitter and an in-loop receiver arrays (ETRA) to conduct a 2-D survey with just one measurement. We present a comprehensive comparison between the new layout and the common approaches based on sensitivity and resolution analyses and show synthetic and field data. The results show that ETRA generates subsurface images at sufficient resolution with significantly lower survey times than other loop layouts.

  1. Imaging of 2-D multichannel land seismic data using an iterative inversion-migration scheme, Naga Thrust and Fold Belt, Assam, India

    NASA Astrophysics Data System (ADS)

    Jaiswal, Priyank; Dasgupta, Rahul

    2010-05-01

    We demonstrate that imaging of 2-D multichannel land seismic data can be effectively accomplished by a combination of reflection traveltime tomography and pre-stack depth migration (PSDM); we refer to the combined process as "the unified imaging". The unified imaging comprises cyclic runs of joint reflection and direct arrival inversion and pre-stack depth migration. From one cycle to another, both the inversion and the migration provide mutual feedbacks that are guided by the geological interpretation. The unified imaging is implemented in two broad stages. The first stage is similar to the conventional imaging except that it involves a significant use of velocity model from the inversion of the direct arrivals for both datuming and stacking velocity analysis. The first stage ends with an initial interval velocity model (from the stacking velocity analysis) and a corresponding depth migrated image. The second stage updates the velocity model and the depth image from the first stage in a cyclic manner; a single cycle comprises a single run of reflection traveltime inversion followed by PSDM. Interfaces used in the inversion are interpretations of the PSDM image in the previous cycle and the velocity model used in PSDM is from the joint inversion in the current cycle. Additionally in every cycle interpreted horizons in the stacked data are inverted as zero-offset reflections for constraining the interfaces; the velocity model is maintained stationary for the zero-offset inversion. A congruency factor, j, which measures the discrepancy between interfaces from the interpretation of the PSDM image and their corresponding counterparts from the inversion of the zero-offset reflections within assigned uncertainties, is computed in every cycle. A value of unity for jindicates that images from both the inversion and the migration are equivalent; at this point the unified imaging is said to have converged and is halted. We apply the unified imaging to 2-D multichannel seismic data from the Naga Thrust and Fold Belt (NTFB), India, were several exploratory wells in the last decade targeting sub-thrust leads in the footwall have failed. This failure is speculatively due to incorrect depth images which are in turn attributed to incorrect velocity models that are developed using conventional methods. The 2-D seismic data in this study is acquired perpendicular to the trend of the NTFB where the outcropping hanging wall has a topographic culmination. The acquisition style is split-spread with 30 m shot and receiver spacing and a nominal fold of 90. The data are recorded with a sample interval of 2 ms. Overall the data have a moderate signal-to-noise ratio and a broad frequency bandwidth of 8-80 Hz. The seismic line contains the failed exploratory well in the central part. The final results from unified imaging (both the depth image and the corresponding velocity model) suggest presence of a triangle zone, which was previously undiscovered. Conventional imaging had falsely portrayed the triangle zone as structural high which was interpreted as an anticline. As a result, the exploratory well, meant to target the anticline, met with pressure changes which were neither expected nor explained. The unified imaging results not only explain the observations in the well but also reveal new leads in the region. The velocity model from unified imaging was also found to be adequate for frequency-domain full-waveform imaging of the hanging wall. Results from waveform inversion are further corroborated by the geological interpretation of the exploratory well.

  2. Spatio-temporal (2D+T) non-rigid registration of real-time 3D echocardiography and cardiovascular MR image sequences

    NASA Astrophysics Data System (ADS)

    Zhang, Weiwei; Brady, J. Michael; Becher, Harald; Noble, J. Alison

    2011-03-01

    In this paper we describe a method to non-rigidly co-register a 2D slice sequence from real-time 3D echocardiography with a 2D cardiovascular MR image sequence. This is challenging because the imaging modalities have different spatial and temporal resolution. Non-rigid registration is required for accurate alignment due to imprecision of cardiac gating and natural motion variations between cardiac cycles. In our approach the deformation field between the imaging modalities is decoupled into temporal and spatial components. First, temporal alignment is performed to establish temporal correspondence between a real-time 3D echocardiography frame and a cardiovascular MR frame. Spatial alignment is then performed using an adaptive non-rigid registration algorithm based on local phase mutual information on each temporally aligned image pair. Experiments on seven volunteer datasets are reported. Evaluation of registration errors based on expert-identified landmarks shows that the spatio-temporal registration algorithm gives a mean registration error of 3.56 ± 0.49 and 3.54 ± 0.27 mm for the short and long axis sequences, respectively.

  3. Sensor fusion of 2D and 3D data for the processing of images of dental imprints

    NASA Astrophysics Data System (ADS)

    Methot, Jean-Francois; Mokhtari, Marielle; Laurendeau, Denis; Poussart, Denis

    1993-08-01

    This paper presents a computer vision system for the acquisition and processing of 3-D images of wax dental imprints. The ultimate goal of the system is to measure a set of 10 orthodontic parameters that will be fed to an expert system for automatic diagnosis of occlusion problems. An approach for the acquisition of range images of both sides of the imprint is presented. Range is obtained from a shape-from-absorption technique applied to a pair of grey-level images obtained at two different wavelengths. The accuracy of the range values is improved using sensor fusion between the initial range image and a reflectance image from the pair of grey-level images. The improved range image is segmented in order to find the interstices between teeth and, following further processing, the type of each tooth on the profile. Once each tooth has been identified, its accurate location on the imprint is found using a region- growing approach and its shape is reconstructed with third degree polynomial functions. The reconstructed shape will be later used by the system to find specific features that are needed to estimate the orthodontic parameters.

  4. Preliminary clinical results: an analyzing tool for 2D optical imaging in detection of active inflammation in rheumatoid arthritis

    NASA Astrophysics Data System (ADS)

    Adi Aizudin Bin Radin Nasirudin, Radin; Meier, Reinhard; Ahari, Carmen; Sievert, Matti; Fiebich, Martin; Rummeny, Ernst J.; No"l, Peter B.

    2011-03-01

    Optical imaging (OI) is a relatively new method in detecting active inflammation of hand joints of patients suffering from rheumatoid arthritis (RA). With the high number of people affected by this disease especially in western countries, the availability of OI as an early diagnostic imaging method is clinically highly relevant. In this paper, we present a newly in-house developed OI analyzing tool and a clinical evaluation study. Our analyzing tool extends the capability of existing OI tools. We include many features in the tool, such as region-based image analysis, hyper perfusion curve analysis, and multi-modality image fusion to aid clinicians in localizing and determining the intensity of inflammation in joints. Additionally, image data management options, such as the full integration of PACS/RIS, are included. In our clinical study we demonstrate how OI facilitates the detection of active inflammation in rheumatoid arthritis. The preliminary clinical results indicate a sensitivity of 43.5%, a specificity of 80.3%, an accuracy of 65.7%, a positive predictive value of 76.6%, and a negative predictive value of 64.9% in relation to clinical results from MRI. The accuracy of inflammation detection serves as evidence to the potential of OI as a useful imaging modality for early detection of active inflammation in patients with rheumatoid arthritis. With our in-house developed tool we extend the usefulness of OI imaging in the clinical arena. Overall, we show that OI is a fast, inexpensive, non-invasive and nonionizing yet highly sensitive and accurate imaging modality.-

  5. Model-based measurement of food portion size for image-based dietary assessment using 3D/2D registration.

    PubMed

    Chen, Hsin-Chen; Jia, Wenyan; Yue, Yaofeng; Li, Zhaoxin; Sun, Yung-Nien; Fernstrom, John D; Sun, Mingui

    2013-10-01

    Dietary assessment is important in health maintenance and intervention in many chronic conditions, such as obesity, diabetes, and cardiovascular disease. However, there is currently a lack of convenient methods for measuring the volume of food (portion size) in real-life settings. We present a computational method to estimate food volume from a single photographical image of food contained in a typical dining plate. First, we calculate the food location with respect to a 3D camera coordinate system using the plate as a scale reference. Then, the food is segmented automatically from the background in the image. Adaptive thresholding and snake modeling are implemented based on several image features, such as color contrast, regional color homogeneity and curve bending degree. Next, a 3D model representing the general shape of the food (e.g., a cylinder, a sphere, etc.) is selected from a pre-constructed shape model library. The position, orientation and scale of the selected shape model are determined by registering the projected 3D model and the food contour in the image, where the properties of the reference are used as constraints. Experimental results using various realistically shaped foods with known volumes demonstrated satisfactory performance of our image based food volume measurement method even if the 3D geometric surface of the food is not completely represented in the input image. PMID:24223474

  6. Model-based measurement of food portion size for image-based dietary assessment using 3D/2D registration

    PubMed Central

    Chen, Hsin-Chen; Jia, Wenyan; Yue, Yaofeng; Li, Zhaoxin; Sun, Yung-Nien; Fernstrom, John D.; Sun, Mingui

    2013-01-01

    Dietary assessment is important in health maintenance and intervention in many chronic conditions, such as obesity, diabetes, and cardiovascular disease. However, there is currently a lack of convenient methods for measuring the volume of food (portion size) in real-life settings. We present a computational method to estimate food volume from a single photographical image of food contained in a typical dining plate. First, we calculate the food location with respect to a 3D camera coordinate system using the plate as a scale reference. Then, the food is segmented automatically from the background in the image. Adaptive thresholding and snake modeling are implemented based on several image features, such as color contrast, regional color homogeneity and curve bending degree. Next, a 3D model representing the general shape of the food (e.g., a cylinder, a sphere, etc.) is selected from a pre-constructed shape model library. The position, orientation and scale of the selected shape model are determined by registering the projected 3D model and the food contour in the image, where the properties of the reference are used as constraints. Experimental results using various realistically shaped foods with known volumes demonstrated satisfactory performance of our image based food volume measurement method even if the 3D geometric surface of the food is not completely represented in the input image. PMID:24223474

  7. Model-based measurement of food portion size for image-based dietary assessment using 3D/2D registration

    NASA Astrophysics Data System (ADS)

    Chen, Hsin-Chen; Jia, Wenyan; Yue, Yaofeng; Li, Zhaoxin; Sun, Yung-Nien; Fernstrom, John D.; Sun, Mingui

    2013-10-01

    Dietary assessment is important in health maintenance and intervention in many chronic conditions, such as obesity, diabetes and cardiovascular disease. However, there is currently a lack of convenient methods for measuring the volume of food (portion size) in real-life settings. We present a computational method to estimate food volume from a single photographic image of food contained on a typical dining plate. First, we calculate the food location with respect to a 3D camera coordinate system using the plate as a scale reference. Then, the food is segmented automatically from the background in the image. Adaptive thresholding and snake modeling are implemented based on several image features, such as color contrast, regional color homogeneity and curve bending degree. Next, a 3D model representing the general shape of the food (e.g., a cylinder, a sphere, etc) is selected from a pre-constructed shape model library. The position, orientation and scale of the selected shape model are determined by registering the projected 3D model and the food contour in the image, where the properties of the reference are used as constraints. Experimental results using various realistically shaped foods with known volumes demonstrated satisfactory performance of our image-based food volume measurement method even if the 3D geometric surface of the food is not completely represented in the input image.

  8. A Bayesian filtering approach to incorporate 2D/3D time-lapse confocal images for tracking angiogenic sprouting cells interacting with the gel matrix.

    PubMed

    Ong, Lee-Ling S; Dauwels, Justin; Ang, Marcelo H; Asada, H Harry

    2014-01-01

    We present a new approach to incorporating information from heterogeneous images of migrating cells in 3D gel. We study 3D angiogenic sprouting, where cells burrow into the gel matrix, communicate with other cells and create vascular networks. We combine time-lapse fluorescent images of stained cell nuclei and transmitted light images of the background gel to track cell trajectories. The nuclei images are sampled less frequently due to photo toxicity. Hence, 3D cell tracking can be performed more reliably when 2D sprout profiles, extracted from gel matrix images, are effectively incorporated. We employ a Bayesian filtering approach to optimally combine the two heterogeneous images with different sampling rates. We construct stochastic models to predict cell locations and sprout profiles and condition the likelihood of nuclei location by the sprout profile. The conditional distribution is non-Gaussian and the cell dynamics is non-linear. To jointly update cell and sprout estimates, we use a Rao-Blackwell particle filter. Simulation and experimental results show accurate tracking of multiple cells along with sprout formation, demonstrating synergistic effects of incorporating the two types of images. PMID:24239653

  9. Automatic organ localizations on 3D CT images by using majority-voting of multiple 2D detections based on local binary patterns and Haar-like features

    NASA Astrophysics Data System (ADS)

    Zhou, Xiangrong; Yamaguchi, Shoutarou; Zhou, Xinxin; Chen, Huayue; Hara, Takeshi; Yokoyama, Ryujiro; Kanematsu, Masayuki; Fujita, Hiroshi

    2013-02-01

    This paper describes an approach to accomplish the fast and automatic localization of the different inner organ regions on 3D CT scans. The proposed approach combines object detections and the majority voting technique to achieve the robust and quick organ localization. The basic idea of proposed method is to detect a number of 2D partial appearances of a 3D target region on CT images from multiple body directions, on multiple image scales, by using multiple feature spaces, and vote all the 2D detecting results back to the 3D image space to statistically decide one 3D bounding rectangle of the target organ. Ensemble learning was used to train the multiple 2D detectors based on template matching on local binary patterns and Haar-like feature spaces. A collaborative voting was used to decide the corner coordinates of the 3D bounding rectangle of the target organ region based on the coordinate histograms from detection results in three body directions. Since the architecture of the proposed method (multiple independent detections connected to a majority voting) naturally fits the parallel computing paradigm and multi-core CPU hardware, the proposed algorithm was easy to achieve a high computational efficiently for the organ localizations on a whole body CT scan by using general-purpose computers. We applied this approach to localization of 12 kinds of major organ regions independently on 1,300 torso CT scans. In our experiments, we randomly selected 300 CT scans (with human indicated organ and tissue locations) for training, and then, applied the proposed approach with the training results to localize each of the target regions on the other 1,000 CT scans for the performance testing. The experimental results showed the possibility of the proposed approach to automatically locate different kinds of organs on the whole body CT scans.

  10. 124I-Epidepride: A PET Radiotracer for Extended Imaging of Dopamine D2/D3 Receptors

    PubMed Central

    Pandey, Suresh; Venugopal, Archana; Kant, Ritu; Coleman, Robert; Mukherjee, Jogeshwar

    2014-01-01

    Objectives A new radiotracer, 124I-epidepride, has been developed for the imaging of dopamine D2/3 receptors (D2/3Rs). 124I-epidepride (half-life of 124I = 4.2days) allows imaging over extended periods compared to 18F-fallypride (half-life of 18F = 0.076days) and may maximize visualization of D2/3Rs in the brain and pancreas (allowing clearance from adjacent organs). D2/3Rs are also present in pancreatic islets where they co-localize with insulin to produce granules and may serve as a surrogate marker for imaging diabetes. Methods 124I-Epidepride was synthesized using N-[[(2S)-1-ethylpyrrolidin-2-yl]methyl]-5-tributyltin-2,3-dimethoxybenzamide and 124I-iodide under no carrier added condition. Rats were used for in vitro and in vivo imaging. Brain slices were incubated with 124I-epidepride (0.75μCi/cc) and nonspecific binding measured with 10 μM haloperidol. Autoradiograms were analyzed by OptiQuant. 124I-Epidepride (0.2 to 0.3 mCi, iv) was administered to rats and brain uptake at 3 hours, 24 hours, and 48 hours post injection was evaluated. Results 124I-Epidepride was synthesized with 50% radiochemical yield and high radiochemical purity (>95%). 124I-Epidepride localized in the striatum with a striatum to cerebellum ratio of 10. Binding was displaced by dopamine and haloperidol. Brain slices demonstrated localization of 124I-epidepride up until 48 hr in the striatum. However, the extent of binding was reduced significantly. Conclusions 124I-Epidepride is a new radiotracer suitable for extended imaging of dopamine D2/3 receptors and may have applications in imaging of receptors in the brain and monitoring pancreatic islet cell grafting. PMID:24602412

  11. Digital breast tomosynthesis: application of 2D digital mammography CAD to detection of microcalcification clusters on planar projection image

    NASA Astrophysics Data System (ADS)

    Samala, Ravi K.; Chan, Heang-Ping; Lu, Yao; Hadjiiski, Lubomir; Wei, Jun; Helvie, Mark

    2015-03-01

    Computer-aided detection (CAD) has the potential to aid radiologists in detection of microcalcification clusters (MCs). CAD for digital breast tomosynthesis (DBT) can be developed by using the reconstructed volume, the projection views or other derivatives as input. We have developed a novel method of generating a single planar projection (PPJ) image from a regularized DBT volume to emphasize the high contrast objects such as microcalcifications while removing the anatomical background and noise. In this work, we adapted a CAD system developed for digital mammography (CADDM) to the PPJ image and compared its performance with our CAD system developed for DBT volumes (CADDBT) in the same set of cases. For microcalcification detection in the PPJ image using the CADDM system, the background removal preprocessing step designed for DM was not needed. The other methods and processing steps in the CADDM system were kept without modification while the parameters were optimized with a training set. The linear discriminant analysis classifier using cluster based features was retrained to generate a discriminant score to be used as decision variable. For view-based FROC analysis, at 80% sensitivity, an FP rate of 1.95/volume and 1.54/image were achieved, respectively, for CADDBT and CADDM in an independent test set. At a threshold of 1.2 FPs per image or per DBT volume, the nonparametric analysis of the area under the FROC curve shows that the optimized CADDM for PPJ is significantly better than CADDBT. However, the performance of CADDM drops at higher sensitivity or FP rate, resulting in similar overall performance between the two CAD systems. The higher sensitivity of the CADDM in the low FP rate region and vice versa for the CADDBT indicate that a joint CAD system combining detection in the DBT volume and the PPJ image has the potential to increase the sensitivity and reduce the FP rate.

  12. High spatiotemporal resolution measurement of regional lung air volumes from 2D phase contrast x-ray images

    SciTech Connect

    Leong, Andrew F. T.; Islam, M. Sirajul; Kitchen, Marcus J.; Fouras, Andreas; Wallace, Megan J.; Hooper, Stuart B.

    2013-04-15

    Purpose: Described herein is a new technique for measuring regional lung air volumes from two-dimensional propagation-based phase contrast x-ray (PBI) images at very high spatial and temporal resolution. Phase contrast dramatically increases lung visibility and the outlined volumetric reconstruction technique quantifies dynamic changes in respiratory function. These methods can be used for assessing pulmonary disease and injury and for optimizing mechanical ventilation techniques for preterm infants using animal models. Methods: The volumetric reconstruction combines the algorithms of temporal subtraction and single image phase retrieval (SIPR) to isolate the image of the lungs from the thoracic cage in order to measure regional lung air volumes. The SIPR algorithm was used to recover the change in projected thickness of the lungs on a pixel-by-pixel basis (pixel dimensions {approx}16.2 {mu}m). The technique has been validated using numerical simulation and compared results of measuring regional lung air volumes with and without the use of temporal subtraction for removing the thoracic cage. To test this approach, a series of PBI images of newborn rabbit pups mechanically ventilated at different frequencies was employed. Results: Regional lung air volumes measured from PBI images of newborn rabbit pups showed on average an improvement of at least 20% in 16% of pixels within the lungs in comparison to that measured without the use of temporal subtraction. The majority of pixels that showed an improvement was found to be in regions occupied by bone. Applying the volumetric technique to sequences of PBI images of newborn rabbit pups, it is shown that lung aeration at birth can be highly heterogeneous. Conclusions: This paper presents an image segmentation technique based on temporal subtraction that has successfully been used to isolate the lungs from PBI chest images, allowing the change in lung air volume to be measured over regions as small as the pixel size. Using this technique, it is possible to measure changes in regional lung volume at high spatial and temporal resolution during breathing at much lower x-ray dose than would be required using computed tomography.

  13. Communication: two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): simultaneous planar imaging and multiplex spectroscopy in a single laser shot.

    PubMed

    Bohlin, Alexis; Kliewer, Christopher J

    2013-06-14

    Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15,000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm(2). PMID:23781772

  14. Ultrafast 2D IR microscopy

    PubMed Central

    Baiz, Carlos R.; Schach, Denise; Tokmakoff, Andrei

    2014-01-01

    We describe a microscope for measuring two-dimensional infrared (2D IR) spectra of heterogeneous samples with μm-scale spatial resolution, sub-picosecond time resolution, and the molecular structure information of 2D IR, enabling the measurement of vibrational dynamics through correlations in frequency, time, and space. The setup is based on a fully collinear “one beam” geometry in which all pulses propagate along the same optics. Polarization, chopping, and phase cycling are used to isolate the 2D IR signals of interest. In addition, we demonstrate the use of vibrational lifetime as a contrast agent for imaging microscopic variations in molecular environments. PMID:25089490

  15. Effects of substrate on 2D materials, graphene, MoS2, WS2, and black phosphorus, investigated by high temperature and spatially resolved Raman scattering and photoluminescence

    NASA Astrophysics Data System (ADS)

    Su, Liqin

    The exploration of a group of new 2D materials, such as graphene and transition metal dichalcogenides, has become the hottest research of interest in recent years. With the dependable techniques of producing 2D materials, particularly mechanical exfoliation and chemical vapor deposition, we are able to study all kinds of their unique properties in mechanical, electrical and optical fields. In this dissertation, we examine the vibrational and thermal properties of four 2D materials---graphene, MoS2, WS2 and black phosphorus---as well as their interaction with the supporting substrates, by using temperature-dependent Raman spectroscopy. Regarding the increasing interests of studying on the fabrication and applications of 2D materials, the role of 2D-material/substrate interaction has seldom been taken into consideration which would significantly affects the quality of the grown films and the performance of the devices. To the best of our knowledge, we are the first to systematically investigate on this issue. At first, we performed temperature-dependent Raman spectroscopy on two graphene samples prepared by CVD and ME up to 400°C, as well as graphite as a reference. The temperature dependence of both graphene samples shows very non-linear behavior for G and 2D bands, but with the CVD-grown graphene more nonlinear. Comparing to the Raman spectra collected before the measurements, the spectra after the measurements exhibit not only a shift of peak position but also a huge broadening of linewidth, especially for CVD-grown graphene. This study implies that the polymeric residues from either scotch tape or PMMA during transfer process are converted to amorphous carbon after annealed at high temperature, which may significantly change the optical and electrical properties of graphene. With the same temperature-dependent Raman technique as graphene, we examine on monolayer MoS2 and WS2, and thin-film black phosphorus and demonstrate that the film morphology and the substrate play very important roles in modifying the properties of the materials. For the films transferred onto SiO2/Si substrates, the E2g 1 mode is only weakly affected by the substrate, whereas the A 1g mode is strongly perturbed, showing a highly nonlinear temperature dependence in Raman peak shift and linewidth. In contrast, for the films epitaxially grown on sapphire substrate, E 2g1 is tuned more significantly by the substrate by showing a much smaller temperature coefficient than the bulk, while A1g is less. A two-round temperature dependent Raman measurements on a transferred MoS2 on SiO2 sample confirm these findings. These experiments suggest that the film-substrate coupling depends sensitively on the preparation method, and in particular on the film morphology for the transferred film. Additionally, temperature-dependent PL spectroscopy of monolayer WS2 shows a 0.2 eV activation energy for CVD-grown films on SiO2/Si substrate. Besides temperature dependent Raman spectroscopy, we also perform PL and Raman mappings on monolayer WS2 triangles prepared by both chemical vapor deposition and transfer, and find both Raman and PL are very sensitive to strain and doping effects. The non-uniform strain distribution over one single triangle is determined both qualitatively and quantitatively through the shift of E2g1 mode and PL peak energy. In transferred WS2 monolayer, comparing to suspended WS2 film a very strong PL quench in WS2 film supported by SiO2/Si substrate is observed, which is attributed to charge transfer between the film and the substrate. Finally, the thermal conductivity of thin-film black phosphorus is determined by its temperature and laser power dependent Raman spectroscopy. An average thermal conductivity of a suspended black phosphorus film has been determined to be 15.8 K/(m·W).

  16. Ultrasonography-based 2D motion-compensated HIFU sonication integrated with reference-free MR temperature monitoring: a feasibility study ex vivo

    NASA Astrophysics Data System (ADS)

    Auboiroux, Vincent; Petrusca, Lorena; Viallon, Magalie; Goget, Thomas; Becker, Christoph D.; Salomir, Rares

    2012-05-01

    Magnetic resonance imaging (MRI) and ultrasonography have been used simultaneously in this ex vivo study for the image-guidance of high intensity focused ultrasound (HIFU) treatment in moving tissue. A ventilator-driven balloon produced periodic and non-rigid (i.e. breathing-like) motion patterns in phantoms. MR-compatible ultrasound (US) imaging enabled near real-time 2D motion tracking based on optical flow detection, while near-harmonic reference-free proton resonance frequency shift (PRFS) MR thermometry (MRT) was used to monitor the thermal buildup on line. Reference-free MRT was applied to gradient-echo echo-planar imaging phase maps acquired at the frame rate of 250 to 300 ms/slice with voxel size 1.25×1.25×5 mm3. The MR-US simultaneous imaging was completely free of mutual interferences while minor RF interferences from the HIFU device were detected in the far field of the US images. The effective duty-cycle of the HIFU sonication was close to 100 % and no off-interval was required to temporally decouple it from the ultrasonography. The motion compensation of the HIFU sonication was achieved with an 8 Hz frame rate and sub-millimeter spatial accuracy, both for single-focus mode and for an iterated multi-foci line scan. Near harmonic reference-less PRFS MRT delivered motion-robust thermal maps perpendicular or parallel to the HIFU beam (0.7 °C precision, 0.5 °C absolute accuracy). Out-of-plane motion compensation was not addressed in this study.

  17. Ultrasonography-based 2D motion-compensated HIFU sonication integrated with reference-free MR temperature monitoring: a feasibility study ex vivo.

    PubMed

    Auboiroux, Vincent; Petrusca, Lorena; Viallon, Magalie; Goget, Thomas; Becker, Christoph D; Salomir, Rares

    2012-05-21

    Magnetic resonance imaging (MRI) and ultrasonography have been used simultaneously in this ex vivo study for the image-guidance of high intensity focused ultrasound (HIFU) treatment in moving tissue. A ventilator-driven balloon produced periodic and non-rigid (i.e. breathing-like) motion patterns in phantoms. MR-compatible ultrasound (US) imaging enabled near real-time 2D motion tracking based on optical flow detection, while near-harmonic reference-free proton resonance frequency shift (PRFS) MR thermometry (MRT) was used to monitor the thermal buildup on line. Reference-free MRT was applied to gradient-echo echo-planar imaging phase maps acquired at the frame rate of 250 to 300 ms/slice with voxel size 1.25×1.25×5 mm(3). The MR-US simultaneous imaging was completely free of mutual interferences while minor RF interferences from the HIFU device were detected in the far field of the US images. The effective duty-cycle of the HIFU sonication was close to 100 % and no off-interval was required to temporally decouple it from the ultrasonography. The motion compensation of the HIFU sonication was achieved with an 8 Hz frame rate and sub-millimeter spatial accuracy, both for single-focus mode and for an iterated multi-foci line scan. Near harmonic reference-less PRFS MRT delivered motion-robust thermal maps perpendicular or parallel to the HIFU beam (0.7 °C precision, 0.5 °C absolute accuracy). Out-of-plane motion compensation was not addressed in this study. PMID:22517112

  18. Comparison of the effect of simple and complex acquisition trajectories on the 2D SPR and 3D voxelized differences for dedicated breast CT imaging

    NASA Astrophysics Data System (ADS)

    Shah, Jainil P.; Mann, Steve D.; McKinley, Randolph L.; Tornai, Martin P.

    2014-03-01

    The 2D scatter-to-primary (SPR) ratios and 3D voxelized difference volumes were characterized for a cone beam breast CT scanner capable of arbitrary (non-traditional) 3D trajectories. The CT system uses a 30x30cm2 flat panel imager with 197 micron pixellation and a rotating tungsten anode x-ray source with 0.3mm focal spot, with an SID of 70cm. Data were acquired for two cylindrical phantoms (12.5cm and 15cm diameter) filled with three different combinations of water and methanol yielding a range of uniform densities. Projections were acquired with two acquisition trajectories: 1) simple-circular azimuthal orbit with fixed tilt; and 2) saddle orbit following a +/-15° sinusoidal trajectory around the object. Projection data were acquired in 2x2 binned mode. Projections were scatter corrected using a beam stop array method, and the 2D SPR was measured on the projections. The scatter corrected and uncorrected data were then reconstructed individually using an iterative ordered subsets convex algorithm, and the 3D difference volumes were calculated as the absolute difference between the two. Results indicate that the 2D SPR is ~7-15% higher on projections with greatest tilt for the saddle orbit, due to the longer x-ray path length through the volume, compared to the 0° tilt projections. Additionally, the 2D SPR increases with object diameter as well as density. The 3D voxelized difference volumes are an estimate of the scatter contribution to the reconstructed attenuation coefficients on a voxel level. They help visualize minor deficiencies and artifacts in the volumes due to correction methods.

  19. A high-throughput imaging auxanometer for roots and hypocotyls of Arabidopsis using a 2D skeletonizing algorithm.

    PubMed

    Fraas, Simon; Niehoff, Vera; Lüthen, Hartwig

    2014-05-01

    Next generation phenotyping of auxin response mutants will be greatly facilitated by the ability to record rapid growth responses in roots and hypocotyls at high throughput and at high temporal resolution. As Arabidopsis seedlings are very tiny and fragile, imaging is the only adequate way for data acquisition. As camera-based systems described before have a limited throughput, we used commercial flatbed scanners to record a large number of simultaneous experiments. We developed Hansa Trace, software for automatically detecting and measuring hypocotyl segments and roots in the images. We validated this system by measuring some well-characterized growth responses to auxins, non-auxins, ATPase activators and apoplastic acidification. The method can be shared on a cooperation basis and is able to perform measurements with minimal user intervention. PMID:24617558

  20. High energy muon induced radioactive nuclides in nickel plate and its use for 2-D muon-beam image profile

    NASA Astrophysics Data System (ADS)

    Kurebayashi, Y.; Sakurai, H.; Takahashi, Y.; Doshita, N.; Kikuchi, S.; Tokanai, F.; Horiuchi, K.; Tajima, Y.; Oe, T.; Sato, T.; Gunji, S.; Inui, E.; Kondo, K.; Iwata, N.; Sasaki, N.; Matsuzaki, H.; Kunieda, S.

    2015-11-01

    Target materials were exposed to a muon beam with an energy of 160 GeV/c at the COMPASS experiment line in CERN-SPS to measure the production cross-sections for muon-induced radionuclides. A muon imager containing four nickel plates, each measuring 100 mm×100 mm, exposed to the IP plate successfully detected the muon beam image during an irradiation period of 33 days. The contrasting density rate of the nickel plate was (5.2±0.7)×10-9 PSL/muon per one-day exposure to IP. The image measured 122 mm and 174 mm in horizontal and vertical lengths, respectively, in relation to the surface of the base, indicating that 50±6% of the muon beam flux is confined to an area of 18% of the whole muon beam. The number of muons estimated from the PSL value in the total beam image area (0.81±0.1)×1013 was comparable to the total muon counts of the ion-chamber at the M2 beam line in the CERN-SPS. The production cross-sections of Cr-51, Mn-54, Co-56, Co-57, and Co-58 in nickel were 0.19±0.08, 0.34±0.06, 0.5±0.05, 3.44±0.07, 0.4±0.03 in the unit of mb, respectively, reducing muon associated particles effects. They are approximately 10 times smaller than that a proceeding study by Heisinger et al.

  1. The Heidelberg Airborne Imaging DOAS Instrument (HAIDI) - a novel imaging DOAS device for 2-D and 3-D imaging of trace gases and aerosols

    NASA Astrophysics Data System (ADS)

    General, S.; Pöhler, D.; Sihler, H.; Bobrowski, N.; Frieß, U.; Zielcke, J.; Horbanski, M.; Shepson, P. B.; Stirm, B. H.; Simpson, W. R.; Weber, K.; Fischer, C.; Platt, U.

    2014-10-01

    Many relevant processes in tropospheric chemistry take place on rather small scales (e.g., tens to hundreds of meters) but often influence areas of several square kilometer. Thus, measurements of the involved trace gases with high spatial resolution are of great scientific interest. In order to identify individual sources and sinks and ultimately to improve chemical transport models, we developed a new airborne instrument, which is based on the well established Differential Optical Absorption Spectroscopy (DOAS) method. The Heidelberg Airborne Imaging DOAS Instrument (HAIDI) is a passive imaging DOAS spectrometer, which is capable of recording horizontal and vertical trace gas distributions with a resolution of better than 100 m. Observable species include NO2, HCHO, C2H2O2, H2O, O3, O4, SO2, IO, OClO and BrO. Here we give a technical description of the instrument including its custom-built spectrographs and CCD detectors. Also first results from measurements with the new instrument are presented. These comprise spatial resolved SO2 and BrO in volcanic plumes, mapped at Mt. Etna (Sicily, Italy), NO2 emissions in the metropolitan area of Indianapolis (Indiana, USA) as well as BrO and NO2 distributions measured during arctic springtime in context of the BRomine, Ozone, and Mercury EXperiment (BROMEX) campaign, which was performed 2012 in Barrow (Alaska, USA).

  2. Impact of stratospheric aircraft on calculations of nitric acid trihydrate cloud surface area densities using NMC temperatures and 2D model constituent distributions

    NASA Technical Reports Server (NTRS)

    Considine, David B.; Douglass, Anne R.

    1994-01-01

    A parameterization of NAT (nitric acid trihydrate) clouds is developed for use in 2D models of the stratosphere. The parameterization uses model distributions of HNO3 and H2O to determine critical temperatures for NAT formation as a function of latitude and pressure. National Meteorological Center temperature fields are then used to determine monthly temperature frequency distributions, also as a function of latitude and pressure. The fractions of these distributions which fall below the critical temperatures for NAT formation are then used to determine the NAT cloud surface area density for each location in the model grid. By specifying heterogeneous reaction rates as functions of the surface area density, it is then possible to assess the effects of the NAT clouds on model constituent distributions. We also consider the increase in the NAT cloud formation in the presence of a fleet of stratospheric aircraft. The stratospheric aircraft NO(x) and H2O perturbations result in increased HNO3 as well as H2O. This increases the probability of NAT formation substantially, especially if it is assumed that the aircraft perturbations are confined to a corridor region.

  3. Effect of strong phonon-phonon coupling on the temperature dependent structural stability and frequency shift of 2D hexagonal boron nitride.

    PubMed

    Anees, P; Valsakumar, M C; Panigrahi, B K

    2016-01-20

    The temperature dependent structural stability, frequency shift and linewidth of 2D hexagonal boron nitride (h-BN) are studied using a combination of lattice dynamics (LD) and molecular dynamics (MD) simulations. The in-plane lattice parameter shows a negative thermal expansion in the whole computed temperature range (0-2000 K). When the in-plane lattice parameter falls below the equilibrium value, the quasi-harmonic bending (ZA) mode frequency becomes imaginary along the Γ-M direction in the Brillouin zone, leading to a structural instability of the 2D sheet. The ZA mode is seen to be stabilized in the dispersion obtained from MD simulations, due to the automatic incorporation of higher order phonon scattering processes in MD, which are absent in a quasi-harmonic dispersion. The mode resolved phonon spectra computed with a quasi-harmonic method predict a blueshift of the longitudinal and transverse (LO/TO) optic mode frequencies with an increase in temperature. On the other hand, both canonical (NVT) and isobaric-isothermal (NPT) ensembles predict a redshift with an increase in temperature, which is more prominent in the NVT ensemble. The strong phonon-phonon coupling dominates over the thermal contraction effect and leads to a redshift in LO/TO mode frequency in the NPT ensemble simulations. The out-of-plane (ZO) optic mode quasi-harmonic frequencies are redshifted due to a membrane effect. The phonon-phonon coupling effects in the NVT and NPT ensemble simulations lead to a further reduction in the ZO mode frequencies. The linewidth of the LO/TO and ZO mode frequencies increases in a monotonic fashion. The temperature dependence of acoustic modes is also analyzed. The quasi-harmonic calculations predict a redshift of ZA mode, and at the same time the TA (transverse acoustic) and LA (longitudinal acoustic) mode frequencies are blueshifted. The strong phonon-phonon coupling in MD simulations causes a redshift of the LA and TA mode frequencies, while the ZA mode frequencies are blueshifted with an increase in temperature. PMID:26705543

  4. Remote Temperature Estimation in Intravascular Photoacoustic Imaging

    PubMed Central

    Sethuraman, Shriram; Aglyamov, Salavat R.; Smalling, Richard W.; Emelianov, Stanislav Y.

    2008-01-01

    Intravascular photoacoustic (IVPA) imaging is based on the detection of laser-induced acoustic waves generated within the arterial tissue under pulsed laser irradiation. Generally, laser radiant energy levels are kept low (20 mJ/cm2) during photoacoustic imaging to conform to general standards for safe use of lasers on biological tissues. However, safety standards in intravascular photoacoustic imaging are not yet fully established. Consequently, monitoring spatio-temporal temperature changes associated with laser-tissue interaction is important to address thermal safety of IVPA imaging. In this study we utilize the IVUS based strain measurements to estimate the laser induced temperature increase. Temporal changes in temperature were estimated in a phantom modeling a vessel with an inclusion. A cross-correlation based time delay estimator was used to assess temperature induced strains produced by different laser radiant energies. The IVUS based remote measurements revealed temperature increases of 0.7±0.3°C, 2.9±0.2 °C and 5.0±0.2 °C, for the laser radiant energies of 30 mJ/cm2, 60 mJ/cm2 and 85 mJ/cm2 respectively. The technique was then used in imaging of ex vivo samples of a normal rabbit aorta. For arterial tissues, a temperature elevation of 1.1°C was observed for a laser fluence of 60 mJ/cm2 and lesser than 1°C for lower energy levels normally associated with IVPA imaging. Therefore, the developed ultrasound technique can be used to monitor temperature during IVPA imaging. Furthermore, the analysis based on the Arrhenius thermal damage model indicates no thermal injury in the arterial tissue; suggesting the safety of IVPA imaging PMID:17935861

  5. Remote temperature estimation in intravascular photoacoustic imaging.

    PubMed

    Sethuraman, Shriram; Aglyamov, Salavat R; Smalling, Richard W; Emelianov, Stanislav Y

    2008-02-01

    Intravascular photoacoustic (IVPA) imaging is based on the detection of laser-induced acoustic waves generated within the arterial tissue under pulsed laser irradiation. In general, laser radiant energy levels are kept low (20 mJ/cm(2)) during photoacoustic imaging to conform to general standards for safe use of lasers on biological tissues. However, safety standards in intravascular photoacoustic imaging are not yet fully established. Consequently, monitoring spatio-temporal temperature changes associated with laser-tissue interaction is important to address thermal safety of IVPA imaging. In this study we utilize the IVUS-based strain measurements to estimate the laser-induced temperature increase. Temporal changes in temperature were estimated in a phantom modeling a vessel with an inclusion. A cross-correlation-based time delay estimator was used to assess temperature-induced strains produced by different laser radiant energies. The IVUS-based remote measurements revealed temperature increases of 0.7+/-0.3 degrees C, 2.9+/-0.2 degrees C and 5.0+/-0.2 degrees C, for the laser radiant energies of 30 mJ/cm(2), 60 mJ/cm(2) and 85 mJ/cm(2), respectively. The technique was then used in imaging of ex vivo samples of a normal rabbit aorta. For arterial tissues, a temperature elevation of 1.1 degrees C was observed for a laser fluence of 60 mJ/cm(2) and lesser than 1 degrees C for lower energy levels normally associated with IVPA imaging. Therefore, the developed ultrasound technique can be used to monitor temperature during IVPA imaging. Furthermore, the analysis based on the Arrhenius thermal damage model indicates no thermal injury in the arterial tissue, suggesting the safety of IVPA imaging. PMID:17935861

  6. Preliminary 3D Depth Migration of a Network of 2D Seismic Lines for Fault Imaging at a Pyramid Lake, Nevada Geothermal Prospect

    NASA Astrophysics Data System (ADS)

    Frary, R.; Louie, J. N.; Pullammanappallil, S.; Eisses, A.

    2011-12-01

    Many of the current geothermal power plants in western Nevada are found in extensional regimes that are associated with dilational faults and fault intersections. Most of these systems are blind and require advanced seismic imaging techniques to map target faults and reduce drilling risk. Surface features including fumaroles, hot springs, or hydrothermal deposits, like travertine and tufa, are indicators of a potential geothermal resource at depth, which still require advanced seismic imaging techniques for efficient development. One of the most notable locations of tufa deposits in western Nevada is in and around Pyramid Lake. With the abundant hydrothermal venting in the area, the tufa deposits indicate a prime locations for geothermal exploration. In 2010 and previous years, we collected about 38 km of vibroseis reflection data in a network of sixteen 2D lines of various orientations off the northwest side of Pyramid Lake. Most of these lines are within an area of only 10 square km. The 2010 survey used three heavy vibrators, and recorded 6-sec records of 8-sec, 10-100 Hz linear sweeps. Source and receiver spacing varied from 17-67 m, with up to 240 channels live for maximum offsets varying from 1000-5000 m, depending on line length. Preliminary 2D processing with first-arrival velocity optimization shows strong fault-plane reflections and several sets of stratigraphic terminations against faults. We interpret three sets of faults, which appear to intersect at about 1.25 km depth. Despite the three fault sets each appearing on several lines, only the lines trending perpendicular to fault strike show direct imaging of fault-plane reflections. We hypothesize that a 3D depth migration will reveal additional direct images of the faults. We are testing this hypothesis with a 3D Kirchhoff prestack migration of the data from this dense network of 2D lines. The 3D depth migration will take full account of lateral velocity changes. This migration should directly image additional steeply dipping fault planes at this prospect. The Pyramid Lake Paiute Tribe will use this information to build 3D geologic and hydrologic models for geothermal power development.

  7. PixFEL: developing a fine pitch, fast 2D X-ray imager for the next generation X-FELs

    NASA Astrophysics Data System (ADS)

    Ratti, L.; Comotti, D.; Fabris, L.; Grassi, M.; Lodola, L.; Malcovati, P.; Manghisoni, M.; Re, V.; Traversi, G.; Vacchi, C.; Bettarini, S.; Casarosa, G.; Forti, F.; Morsani, F.; Paladino, A.; Paoloni, E.; Rizzo, G.; Benkechkache, M. A.; Dalla Betta, G.-F.; Mendicino, R.; Pancheri, L.; Verzellesi, G.; Xu, H.

    2015-10-01

    The PixFEL project is conceived as the first stage of a long term research program aiming at the development of advanced X-ray imaging instrumentation for applications at the free electron laser (FEL) facilities. The project aims at substantially advancing the state-of-the-art in the field of 2D X-ray imaging by exploring cutting-edge solutions for sensor development, for integration processes and for readout channel architectures. The main focus is on the development of the fundamental microelectronic building blocks for detector readout and on the technologies for the assembly of a multilayer module with minimum dead area. This work serves the purpose of introducing the main features of the project, together with the simulation results leading to the first prototyping run.

  8. Infrared absorption imaging of 2D supersonic jet expansions: Free expansion, cluster formation, and shock wave patterns.

    PubMed

    Zischang, Julia; Suhm, Martin A

    2013-07-14

    N2O/He gas mixtures are expanded through a 10 × 0.5 mm(2) slit nozzle and imaged by direct absorption vibrational spectroscopy, employing a HgCdTe focal plane array detector after interferometric modulation. N2O cluster formation in the free supersonic expansion is visualized. The expansion structure behind the frontal shock is investigated as a function of background pressure. At high pressures, a sequence of stationary density peaks along a narrow directed flow channel is characterized. The potential of the technique for the elucidation of aggregation mechanisms is emphasized. PMID:23862934

  9. 2D and 3D soil moisture imaging using a sensor-based platform moving inside a subsurface network of pipes

    NASA Astrophysics Data System (ADS)

    Gravalos, I.; Moshou, D.; Loutridis, S.; Gialamas, Th.; Kateris, D.; Bompolas, E.; Tsiropoulos, Z.; Xyradakis, P.; Fountas, S.

    2013-08-01

    In this study a prototype sensor-based platform moving inside a subsurface network of pipes with the task of monitoring the soil moisture content is presented. It comprises of a mobile platform, a modified commercial soil moisture sensor (Diviner 2000), a network of subsurface polyvinylchloride (PVC) access pipes, driving hardware and image processing software. The software allows the composition of two-dimensional (2D) or three-dimensional (3D) images with high accuracy and at a large scale. The 3D soil moisture images are created by using 2D slices for better illustration of the soil moisture variability. Three case studies of varying soil moisture content using an experimental soil tank were examined. In the first case study, the irrigation water was applied uniformly on the entire tank surface. In second and third case studies, the irrigation water was applied uniformly only on the surface of the intermediate and last part of the soil tank respectively. The processed images give a detailed description of the soil moisture distribution of a layer at 15 cm depth under the soil surface in the tank. In all case studies that have been investigated, the distribution of soil moisture was characterized by a significant variability (difference between poorly and well-drained regions) of the soil tank. A very poorly-drained region was located in the middle of the soil tank, while well-drained soil areas were located southwest and northeast. The knowledge of the spatial and temporal distribution of soil moisture is a valuable tool for proper management of crop irrigation.

  10. Crystal structure and temperature-dependent fluorescent property of a 2D cadmium (II) complex based on 3,6-dibromobenzene-1,2,4,5-tetracarboxylic acid

    NASA Astrophysics Data System (ADS)

    Zhang, Liang-Liang; Guo, Yu; Wei, Yan-Hui; Guo, Jie; Wang, Xing-Po; Sun, Dao-Feng

    2013-04-01

    A new cadmium (II) organic coordination polymers [Cd(dbtec)0.5(H2O)3]·H2O (1), has been constructed based on 3,6-dibromobenzene-1,2,4,5-tetracarboxylic acid (H4dbtec), and characterized by elemental analysis (EA), infrared spectroscopy (IR), powder X-ray diffraction (PXRD), and single crystal X-ray diffraction. In 1, μ2-η1:η1 and μ4-η2:η2 dbtec ligands link four hepta-coordinated CdII ions to form a 2D 44 topological layer structure, which is further connected into an interesting 3D network by hydrogen bond and Br⋯O halogen bond. Moreover, the thermal stabilities, solid ultraviolet spectroscopy and temperature-dependent fluorescent properties of 1 were investigated.

  11. A frequency-based approach to locate common structure for 2D-3D intensity-based registration of setup images in prostate radiotherapy

    SciTech Connect

    Munbodh, Reshma; Chen Zhe; Jaffray, David A.; Moseley, Douglas J.; Knisely, Jonathan P. S.; Duncan, James S.

    2007-07-15

    In many radiotherapy clinics, geometric uncertainties in the delivery of 3D conformal radiation therapy and intensity modulated radiation therapy of the prostate are reduced by aligning the patient's bony anatomy in the planning 3D CT to corresponding bony anatomy in 2D portal images acquired before every treatment fraction. In this paper, we seek to determine if there is a frequency band within the portal images and the digitally reconstructed radiographs (DRRs) of the planning CT in which bony anatomy predominates over non-bony anatomy such that portal images and DRRs can be suitably filtered to achieve high registration accuracy in an automated 2D-3D single portal intensity-based registration framework. Two similarity measures, mutual information and the Pearson correlation coefficient were tested on carefully collected gold-standard data consisting of a kilovoltage cone-beam CT (CBCT) and megavoltage portal images in the anterior-posterior (AP) view of an anthropomorphic phantom acquired under clinical conditions at known poses, and on patient data. It was found that filtering the portal images and DRRs during the registration considerably improved registration performance. Without filtering, the registration did not always converge while with filtering it always converged to an accurate solution. For the pose-determination experiments conducted on the anthropomorphic phantom with the correlation coefficient, the mean (and standard deviation) of the absolute errors in recovering each of the six transformation parameters were {theta}{sub x}:0.18(0.19) deg., {theta}{sub y}:0.04(0.04) deg., {theta}{sub z}:0.04(0.02) deg., t{sub x}:0.14(0.15) mm, t{sub y}:0.09(0.05) mm, and t{sub z}:0.49(0.40) mm. The mutual information-based registration with filtered images also resulted in similarly small errors. For the patient data, visual inspection of the superimposed registered images showed that they were correctly aligned in all instances. The results presented in this paper suggest that robust and accurate registration can be achieved with intensity-based methods by focusing on rigid bony structures in the images while diminishing the influence of artifacts with similar frequencies as soft tissue.

  12. 2D soft x-ray system on DIII-D for imaging the magnetic topology in the pedestal region

    SciTech Connect

    Shafer, M. W.; Battaglia, D. J.; Unterberg, E. A.; Hillis, D. L.; Maingi, R.; Evans, T. E.

    2010-10-15

    A new tangential two-dimensional soft x-ray imaging system (SXRIS) is being designed to examine the edge island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of the calculated vacuum islands may play a role in the suppression of edge-localized modes via resonant magnetic perturbations (RMPs). The SXRIS is intended to improve the understanding of three-dimensional (3D) phenomena associated with RMPs. This system utilizes a tangential view with a pinhole imaging system and spectral filtering with beryllium foils. SXR emission is chosen to avoid line radiation and allows suitable signal at the top of a H-mode pedestal where T{sub e}{approx}1-2 keV. A synthetic diagnostic calculation based on 3D SXR emissivity estimates is used to help assess signal levels and resolution of the design. A signal-to-noise ratio of 10 at 1 cm resolution is expected for the perturbed signals, which are sufficient to resolve most of the predicted vacuum island sizes.

  13. 2D soft x-ray system on DIII-D for imaging the magnetic topology in the pedestal region

    SciTech Connect

    Shafer, M.W.; Battaglia, D. J.; Unterberg, Ezekial A; Evans, T. E.; Hillis, Donald Lee; Maingi, R.

    2010-01-01

    A new tangential two-dimensional soft x-ray imaging system (SXRIS) is being designed to examine the edge island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of the calculated vacuum islands may play a role in the suppression of edge-localized modes via resonant magnetic perturbations (RMPs). The SXRIS is intended to improve the understanding of three-dimensional (3D) phenomena associated with RMPs. This system utilizes a tangential view with a pinhole imaging system and spectral filtering with beryllium foils. SXR emission is chosen to avoid line radiation and allows suitable signal at the top of a H-mode pedestal where T(e) similar to 1-2 keV. A synthetic diagnostic calculation based on 3D SXR emissivity estimates is used to help assess signal levels and resolution of the design. A signal-to-noise ratio of 10 at 1 cm resolution is expected for the perturbed signals, which are sufficient to resolve most of the predicted vacuum island sizes.

  14. 2D soft x-ray system on DIII-D for imaging the magnetic topology in the pedestal regiona)

    NASA Astrophysics Data System (ADS)

    Shafer, M. W.; Battaglia, D. J.; Unterberg, E. A.; Evans, T. E.; Hillis, D. L.; Maingi, R.

    2010-10-01

    A new tangential two-dimensional soft x-ray imaging system (SXRIS) is being designed to examine the edge island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of the calculated vacuum islands may play a role in the suppression of edge-localized modes via resonant magnetic perturbations (RMPs). The SXRIS is intended to improve the understanding of three-dimensional (3D) phenomena associated with RMPs. This system utilizes a tangential view with a pinhole imaging system and spectral filtering with beryllium foils. SXR emission is chosen to avoid line radiation and allows suitable signal at the top of a H-mode pedestal where Te˜1-2 keV. A synthetic diagnostic calculation based on 3D SXR emissivity estimates is used to help assess signal levels and resolution of the design. A signal-to-noise ratio of 10 at 1 cm resolution is expected for the perturbed signals, which are sufficient to resolve most of the predicted vacuum island sizes.

  15. 2D soft x-ray system on DIII-D for imaging the magnetic topology in the pedestal region.

    PubMed

    Shafer, M W; Battaglia, D J; Unterberg, E A; Evans, T E; Hillis, D L; Maingi, R

    2010-10-01

    A new tangential two-dimensional soft x-ray imaging system (SXRIS) is being designed to examine the edge island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of the calculated vacuum islands may play a role in the suppression of edge-localized modes via resonant magnetic perturbations (RMPs). The SXRIS is intended to improve the understanding of three-dimensional (3D) phenomena associated with RMPs. This system utilizes a tangential view with a pinhole imaging system and spectral filtering with beryllium foils. SXR emission is chosen to avoid line radiation and allows suitable signal at the top of a H-mode pedestal where T(e)∼1-2 keV. A synthetic diagnostic calculation based on 3D SXR emissivity estimates is used to help assess signal levels and resolution of the design. A signal-to-noise ratio of 10 at 1 cm resolution is expected for the perturbed signals, which are sufficient to resolve most of the predicted vacuum island sizes. PMID:21034061

  16. Modeling and Measurement of 3D Deformation of Scoliotic Spine Using 2D X-ray Images

    NASA Astrophysics Data System (ADS)

    Li, Hao; Leow, Wee Kheng; Huang, Chao-Hui; Howe, Tet Sen

    Scoliosis causes deformations such as twisting and lateral bending of the spine. To correct scoliotic deformation, the extents of 3D spinal deformation need to be measured. This paper studies the modeling and measurement of scoliotic spine based on 3D curve model. Through modeling the spine as a 3D Cosserat rod, the 3D structure of a scoliotic spine can be recovered by obtaining the minimum potential energy registration of the rod to the scoliotic spine in the x-ray image. Test results show that it is possible to obtain accurate 3D reconstruction using only the landmarks in a single view, provided that appropriate boundary conditions and elastic properties are included as constraints.

  17. Development of an integrated approach for evaluation of 2-D gel image analysis: Impact of multiple proteins in single spots on comparative proteomics in conventional 2-D gel/MALDI workflow

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With 2-D gel mapping, it is often observed that essentially identical proteins migrate to different positions in the gel, while some seemingly well-resolved protein spots consist of multiple proteins. These observations can undermine the validity of gel-based comparative proteomic studies. Through...

  18. In vivo and in vitro characterization of R(+)-FIDA2, a novel dopamine D2/D3 receptor imaging agent

    SciTech Connect

    Vessotskie, J.; Kung, M.P.; Ramaniello, G.

    1994-05-01

    FIDA2, (R)-(+)-2,3-dimethoxy-5-iodo-N-[1-(4`-fluorobenzyl)-2-pyrrolidinyl)-methyl]benzamide, is a new dopamine D2/D3 receptor imaging agent that can be labeled with either I-123 or F-18 for SPECT or PET imaging. In vitro binding studies of I-125 FIDA2 using dopamine D2 or D3 receptors expressed in Sf9 cells showed Kd values of 0.04 and 0.05 nM, respectively. In rat striatal homogenates, which contain a high density of dopamine D2 receptors, the ligand displayed a Kd of 0.04-0.06 nM. A series of in vivo SPECT images (transaxial sections, 2 mm) showed the radioactivity was localized in the area of the basal ganglia and reached peak concentrations in 11.2 {plus_minus} 5.9 min. The activity cleared at a rate of 33.5 {plus_minus} 9.4 %/hr. The target to nontarget ratios (basal ganglia to cerebellum) at time of peak, 1 hr, 2 hr and 3 hr p.i., were 1.1 {plus_minus} 0.4 (n=21), 3.5 {plus_minus} 1.0 (n=20), 6.3 {plus_minus} 2.9 (n=9, and 8.14 {plus_minus} 4.7 (n=9), respectively. At 90 min an injection of haloperidol or raclopride, dopamine D2/D3 receptor antagonists, displaced target activity but an injection of SCH23390, a dopamine D1 receptor antagonist, had little effect on activity in the basal ganglia. In addition, an injection of R-(+)-7-OH-PIPAT, a new ligand that is selective for the dopamine D3 receptor and the high affinity state of the dopamine D2 receptor, showed partial displacement ({approximately}15%) of I-123 FIDA2 binding in the basal ganglia. These studies indicate that FIDA2 may be a useful ligand for in vivo imaging of dopamine D2/D3 receptors.

  19. A 2D 4×4 Channel Readout ASIC for Pixelated CdTe Detectors for Medical Imaging Applications

    PubMed Central

    Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Martínez, Ricardo; Puigdengoles, Carles

    2015-01-01

    We present a 16-channel readout integrated circuit (ROIC) with nanosecond-resolution time to digital converter (TDC) for pixelated Cadmium Telluride (CdTe) gamma-ray detectors. The 4 × 4 pixel array ROIC is the proof of concept of the 10 × 10 pixel array readout ASIC for positron-emission tomography (PET) scanner, positron-emission mammography (PEM) scanner, and Compton gamma camera. The electronics of each individual pixel integrates an analog front-end with switchable gain, an analog to digital converter (ADC), configuration registers, and a 4-state digital controller. For every detected photon, the pixel electronics provides the energy deposited in the detector with 10-bit resolution, and a fast trigger signal for time stamp. The ASIC contains the 16-pixel matrix electronics, a digital controller, five global voltage references, a TDC, a temperature sensor, and a band-gap based current reference. The ASIC has been fabricated with TSMC 0.25 μm mixed-signal CMOS technology and occupies an area of 5.3 mm × 6.8 mm. The TDC shows a resolution of 95.5 ps, a precision of 600 ps at full width half maximum (FWHM), and a power consumption of 130 μW. In acquisition mode, the total power consumption of every pixel is 200 μW. An equivalent noise charge (ENC) of 160 e−RMS at maximum gain and negative polarity conditions has been measured at room temperature. PMID:26744545

  20. Revealing high room and low temperatures mobilities of 2D holes in a strained Ge quantum well heterostructures grown on a standard Si(0 0 1) substrate

    NASA Astrophysics Data System (ADS)

    Myronov, Maksym; Morrison, Christopher; Halpin, John; Rhead, Stephen; Foronda, Jamie; Leadley, David

    2015-08-01

    Carrier mobility is one of the most important parameters of any semiconductor material, determining its suitability for applications in a large variety of electronic devices including field effect transistors (FETs). Today the capabilities of modern planar Si FET devices are almost exhausted and researchers are seeking either new device architectures or new materials. Here we report an extremely high room temperature (at 293 K) 2D hole gas (2DHG) drift mobility of 4500 cm2 V-1 s-1 at a carrier density of 1.2 × 1011 cm-2 obtained in a compressively strained Ge quantum well (QW) heterostructure, grown by an industrial type chemical vapor deposition system on a standard Si(0 0 1) substrate. The low-temperature Hall mobility and carrier density of this structure, measured at 333 mK, are 777,000 cm2 V-1 s-1 and 1.9 × 1011 cm-2, respectively. These hole mobilities are the highest not only among the group-IV Si and Ge based semiconductors, but also among p-type III-V and II-VI materials. The obtained room temperature mobility is substantially higher than those reported so far in strained Ge QW heterostructures and reveals a huge potential for further applications of this material in a wide variety of electronic devices.

  1. ECE imaging of electron temperature and electron temperature fluctuations (invited)

    SciTech Connect

    Deng, B. H.; Domier, C. W.; Luhmann, N. C.; Brower, D. L.; Cima, G.; Donne, A. J. H.; Oyevaar, T.; van de Pol, M. J.

    2001-01-01

    Electron cyclotron emission imaging (ECE imaging or ECEI) is a novel plasma diagnostic technique for the study of electron temperature profiles and fluctuations in magnetic fusion plasma devices. Instead of a single receiver located in the tokamak midplane as in conventional ECE radiometers, ECEI systems utilize large diameter imaging optics coupled with planar millimeter-wave imaging arrays to form multichannel ECE diagnostics with excellent spatial resolution. Combined with specially designed imaging optics, the use of these compact, low cost arrays has resulted in the excellent spatial resolution of the ECEI systems, the unique capability of two-dimensional measurements, and flexibility in the measurement of plasma fluctuations. Technical details and principles of this emerging diagnostic technique are described in this article. Illustrative experimental results are presented, together with a discussion of the further development of the diagnostic.

  2. Spatially selective 2D RF inner field of view (iFOV) diffusion kurtosis imaging (DKI) of the pediatric spinal cord.

    PubMed

    Conklin, Chris J; Middleton, Devon M; Alizadeh, Mahdi; Finsterbusch, Jürgen; Raunig, David L; Faro, Scott H; Shah, Pallav; Krisa, Laura; Sinko, Rebecca; Delalic, Joan Z; Mulcahey, M J; Mohamed, Feroze B

    2016-01-01

    Magnetic resonance based diffusion imaging has been gaining more utility and clinical relevance over the past decade. Using conventional echo planar techniques, it is possible to acquire and characterize water diffusion within the central nervous system (CNS); namely in the form of Diffusion Weighted Imaging (DWI) and Diffusion Tensor Imaging (DTI). While each modality provides valuable clinical information in terms of the presence of diffusion and its directionality, both techniques are limited to assuming an ideal Gaussian distribution for water displacement with no intermolecular interactions. This assumption neglects pathological processes that are not Gaussian therefore reducing the amount of potentially clinically relevant information. Additions to the Gaussian distribution measured by the excess kurtosis, or peakedness, of the probabilistic model provide a better understanding of the underlying cellular structure. The objective of this work is to provide mathematical and experimental evidence that Diffusion Kurtosis Imaging (DKI) can offer additional information about the micromolecular environment of the pediatric spinal cord. This is accomplished by a more thorough characterization of the nature of random water displacement within the cord. A novel DKI imaging sequence based on a tilted 2D spatially selective radio frequency pulse providing reduced field of view (FOV) imaging was developed, implemented, and optimized on a 3 Tesla MRI scanner, and tested on pediatric subjects (healthy subjects: 15; patients with spinal cord injury (SCI):5). Software was developed and validated for post processing of the DKI images and estimation of the tensor parameters. The results show statistically significant differences in mean kurtosis (p < 0.01) and radial kurtosis (p < 0.01) between healthy subjects and subjects with SCI. DKI provides incremental and novel information over conventional diffusion acquisitions when coupled with higher order estimation algorithms. PMID:26909329

  3. 2D/3D Image fusion for accurate target localization and evaluation of a mask based stereotactic system in fractionated stereotactic radiotherapy of cranial lesions

    SciTech Connect

    Jin, J.-Y.; Ryu, Samuel; Faber, Kathleen; Mikkelsen, Tom; Chen Qing; Li Shidong; Movsas, Benjamin

    2006-12-15

    The purpose of this study was to evaluate the accuracy of a two-dimensional (2D) to three-dimensional (3D) image-fusion-guided target localization system and a mask based stereotactic system for fractionated stereotactic radiotherapy (FSRT) of cranial lesions. A commercial x-ray image guidance system originally developed for extracranial radiosurgery was used for FSRT of cranial lesions. The localization accuracy was quantitatively evaluated with an anthropomorphic head phantom implanted with eight small radiopaque markers (BBs) in different locations. The accuracy and its clinical reliability were also qualitatively evaluated for a total of 127 fractions in 12 patients with both kV x-ray images and MV portal films. The image-guided system was then used as a standard to evaluate the overall uncertainty and reproducibility of the head mask based stereotactic system in these patients. The phantom study demonstrated that the maximal random error of the image-guided target localization was {+-}0.6 mm in each direction in terms of the 95% confidence interval (CI). The systematic error varied with measurement methods. It was approximately 0.4 mm, mainly in the longitudinal direction, for the kV x-ray method. There was a 0.5 mm systematic difference, primarily in the lateral direction, between the kV x-ray and the MV portal methods. The patient study suggested that the accuracy of the image-guided system in patients was comparable to that in the phantom. The overall uncertainty of the mask system was {+-}4 mm, and the reproducibility was {+-}2.9 mm in terms of 95% CI. The study demonstrated that the image guidance system provides accurate and precise target positioning.

  4. Spatially selective 2D RF inner field of view (iFOV) diffusion kurtosis imaging (DKI) of the pediatric spinal cord

    PubMed Central

    Conklin, Chris J.; Middleton, Devon M.; Alizadeh, Mahdi; Finsterbusch, Jürgen; Raunig, David L.; Faro, Scott H.; Shah, Pallav; Krisa, Laura; Sinko, Rebecca; Delalic, Joan Z.; Mulcahey, M.J.; Mohamed, Feroze B.

    2016-01-01

    Magnetic resonance based diffusion imaging has been gaining more utility and clinical relevance over the past decade. Using conventional echo planar techniques, it is possible to acquire and characterize water diffusion within the central nervous system (CNS); namely in the form of Diffusion Weighted Imaging (DWI) and Diffusion Tensor Imaging (DTI). While each modality provides valuable clinical information in terms of the presence of diffusion and its directionality, both techniques are limited to assuming an ideal Gaussian distribution for water displacement with no intermolecular interactions. This assumption neglects pathological processes that are not Gaussian therefore reducing the amount of potentially clinically relevant information. Additions to the Gaussian distribution measured by the excess kurtosis, or peakedness, of the probabilistic model provide a better understanding of the underlying cellular structure. The objective of this work is to provide mathematical and experimental evidence that Diffusion Kurtosis Imaging (DKI) can offer additional information about the micromolecular environment of the pediatric spinal cord. This is accomplished by a more thorough characterization of the nature of random water displacement within the cord. A novel DKI imaging sequence based on a tilted 2D spatially selective radio frequency pulse providing reduced field of view (FOV) imaging was developed, implemented, and optimized on a 3 Tesla MRI scanner, and tested on pediatric subjects (healthy subjects: 15; patients with spinal cord injury (SCI):5). Software was developed and validated for post processing of the DKI images and estimation of the tensor parameters. The results show statistically significant differences in mean kurtosis (p < 0.01) and radial kurtosis (p < 0.01) between healthy subjects and subjects with SCI. DKI provides incremental and novel information over conventional diffusion acquisitions when coupled with higher order estimation algorithms. PMID:26909329

  5. An hybrid detector GEM-ASIC for 2-D soft X-ray imaging for laser produced plasma and pulsed sources

    NASA Astrophysics Data System (ADS)

    Pacella, D.; Claps, G.; De Angelis, R.; Murtas, F.

    2016-03-01

    The following paper presents a new 2-D detector (`GEMpix') in the soft X-ray range, having a wide dynamic range thanks to its intrisic gain, working in charge integration mode to be used for diagnosing laser produced plasma (LPP) or X-ray pulsed sources. It is a gas detector based on the Gas Electron Multiplier (GEM) technology with a quad-medipix chip as read-out electronics. In our prototype, the substitution of semiconductor material with a gas triple-GEM allows several advantages with respect to the detectors commonly used in LPP, as X-ray CCDs and Micro Channel Plates or Image Plates. In these experiments the configuration Time-over-Threshold (ToT) has been used, to measure the total charge released to the gas and collected by each pixel, integrated over the X-ray burst duration. Intensity response and spatial resolution has been measured first in laboratory for calibration, as function of the voltage applied to the GEMs, in single photon regime with energies between 3.7 and 17 keV. Subsequently it has been tested at the ABC laser facility (ENEA, Frascati). In this case, we measured the X-rays produced when the ABC neodymium laser, with pulse of 50 J and 3 ns time width, hits plane targets of aluminum. 2-D images have been acquired by means of a pinhole configuration with magnification 1.5 and 50 μ m of spatial resolution. The results are encouraging regarding the capability of this imaging detector to work in experiments where soft X-ray emissivity varies over many orders of magnitude.

  6. Intraoperative Image-based Multiview 2D/3D Registration for Image-Guided Orthopaedic Surgery: Incorporation of Fiducial-Based C-Arm Tracking and GPU-Acceleration

    PubMed Central

    Armand, Mehran; Armiger, Robert S.; Kutzer, Michael D.; Basafa, Ehsan; Kazanzides, Peter; Taylor, Russell H.

    2012-01-01

    Intraoperative patient registration may significantly affect the outcome of image-guided surgery (IGS). Image-based registration approaches have several advantages over the currently dominant point-based direct contact methods and are used in some industry solutions in image-guided radiation therapy with fixed X-ray gantries. However, technical challenges including geometric calibration and computational cost have precluded their use with mobile C-arms for IGS. We propose a 2D/3D registration framework for intraoperative patient registration using a conventional mobile X-ray imager combining fiducial-based C-arm tracking and graphics processing unit (GPU)-acceleration. The two-stage framework 1) acquires X-ray images and estimates relative pose between the images using a custom-made in-image fiducial, and 2) estimates the patient pose using intensity-based 2D/3D registration. Experimental validations using a publicly available gold standard dataset, a plastic bone phantom and cadaveric specimens have been conducted. The mean target registration error (mTRE) was 0.34 ± 0.04 mm (success rate: 100%, registration time: 14.2 s) for the phantom with two images 90° apart, and 0.99 ± 0.41 mm (81%, 16.3 s) for the cadaveric specimen with images 58.5° apart. The experimental results showed the feasibility of the proposed registration framework as a practical alternative for IGS routines. PMID:22113773

  7. Efficient training of convolutional deep belief networks in the frequency domain for application to high-resolution 2D and 3D images.

    PubMed

    Brosch, Tom; Tam, Roger

    2015-01-01

    Deep learning has traditionally been computationally expensive, and advances in training methods have been the prerequisite for improving its efficiency in order to expand its application to a variety of image classification problems. In this letter, we address the problem of efficient training of convolutional deep belief networks by learning the weights in the frequency domain, which eliminates the time-consuming calculation of convolutions. An essential consideration in the design of the algorithm is to minimize the number of transformations to and from frequency space. We have evaluated the running time improvements using two standard benchmark data sets, showing a speed-up of up to 8 times on 2D images and up to 200 times on 3D volumes. Our training algorithm makes training of convolutional deep belief networks on 3D medical images with a resolution of up to 128×128×128 voxels practical, which opens new directions for using deep learning for medical image analysis. PMID:25380341

  8. Simultaneous microwave imaging system for density and temperature fluctuation measurements on TEXTOR (invited)

    SciTech Connect

    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

    2004-10-01

    Diagnostic systems for fluctuation measurements in plasmas are, of necessity, evolving from simple one-dimensional (1D) systems to multidimensional systems due to the complexity of the magnetohydrodynamics (MHD) and turbulence physics of plasmas as 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, have been developed for Toroidal EXperiment for Technology Oriented Research (TEXTOR). The MIR system was installed on Textor and the experiment was performed in September, 2003. Subsequent MIR campaigns have yielded poloidally resolved spectra and assessments of poloidal velocity. The 2D ECE imaging system (with a total of 128 channels), installed on TEXTOR in December, 2003, successfully captured the first true 2D images of T{sub e} fluctuations of m=1 oscillations ('sawteeth') near the q{approx}1 surface.

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

    SciTech Connect

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

    2004-05-07

    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 {approx} 1 surface for the first time.

  10. 2D-1H proton magnetic resonance spectroscopic imaging study on brain metabolite alterations in patients with diabetic hypertension

    PubMed Central

    CAO, ZHEN; YE, BI-DI; SHEN, ZHI-WEI; CHENG, XIAO-FANG; YANG, ZHONG-XIAN; LIU, YAN-YAN; WU, REN-HUA; GENG, KUAN; XIAO, YE-YU

    2015-01-01

    The aim of the present study was to investigate the possible metabolic alterations in the frontal cortex and parietal white matter in patients with diabetic hypertension (DHT) using proton magnetic resonance (MR) spectroscopic imaging. A total of 33 DHT patients and 30 healthy control subjects aged between 45 and 75 were included in the present study. All subjects were right-handed. The spectroscopy data were collected using a GE Healthcare 1.5T MR scanner. The multi-voxels were located in the semioval center (repetition time/echo time=1,500 ms/35 ms). The area of interest was 8102 cm in volume and contained the two sides of the frontal cortex and the parietal white matter. The spectra data were processed using SAGE software. The ratios of brain metabolite concentrations, particularly for N-acetylaspartate (NAA)/creatine (Cr) and Choline (Cho)/Cr were calculated and analyzed. Statistical analyses were performed using SPSS 17.0. The NAA/Cr ratio of the bilateral prefrontal cortex of the DHT group was significantly lower than that of the control group (left t=?7.854, P=0.000 and right t= ?5.787, P=0.000), The Cho/Cr ratio was also much lower than the control group (left t=2.422, P=0.024 and right t=2.920, P=0.007). NAA/Cr ratio of the left parietal white matter of the DHT group was extremely lower than that of the control group (t=?4.199, P=0.000). Therefore, DHT may result in metabolic disorders in the frontal cortex and parietal white matter but the metabolic alterations are different in various regions of the brain. The alteration in cerebral metabolism is associated with diabetes and hypertension. The ratios of NAA/Cr and Cho/Cr are potential metabolic markers for the brain damage induced by DHT. PMID:25652580

  11. 3D-2D image registration for target localization in spine surgery: investigation of similarity metrics providing robustness to content mismatch

    NASA Astrophysics Data System (ADS)

    De Silva, T.; Uneri, A.; Ketcha, M. D.; Reaungamornrat, S.; Kleinszig, G.; Vogt, S.; Aygun, N.; Lo, S.-F.; Wolinsky, J.-P.; Siewerdsen, J. H.

    2016-04-01

    In image-guided spine surgery, robust three-dimensional to two-dimensional (3D-2D) registration of preoperative computed tomography (CT) and intraoperative radiographs can be challenged by the image content mismatch associated with the presence of surgical instrumentation and implants as well as soft-tissue resection or deformation. This work investigates image similarity metrics in 3D-2D registration offering improved robustness against mismatch, thereby improving performance and reducing or eliminating the need for manual masking. The performance of four gradient-based image similarity metrics (gradient information (GI), gradient correlation (GC), gradient information with linear scaling (GS), and gradient orientation (GO)) with a multi-start optimization strategy was evaluated in an institutional review board-approved retrospective clinical study using 51 preoperative CT images and 115 intraoperative mobile radiographs. Registrations were tested with and without polygonal masks as a function of the number of multistarts employed during optimization. Registration accuracy was evaluated in terms of the projection distance error (PDE) and assessment of failure modes (PDE  >  30 mm) that could impede reliable vertebral level localization. With manual polygonal masking and 200 multistarts, the GC and GO metrics exhibited robust performance with 0% gross failures and median PDE  <  6.4 mm (±4.4 mm interquartile range (IQR)) and a median runtime of 84 s (plus upwards of 1-2 min for manual masking). Excluding manual polygonal masks and decreasing the number of multistarts to 50 caused the GC-based registration to fail at a rate of  >14% however, GO maintained robustness with a 0% gross failure rate. Overall, the GI, GC, and GS metrics were susceptible to registration errors associated with content mismatch, but GO provided robust registration (median PDE  =  5.5 mm, 2.6 mm IQR) without manual masking and with an improved runtime (29.3 s). The GO metric improved the registration accuracy and robustness in the presence of strong image content mismatch. This capability could offer valuable assistance and decision support in spine level localization in a manner consistent with clinical workflow.

  12. 3D-2D image registration for target localization in spine surgery: investigation of similarity metrics providing robustness to content mismatch.

    PubMed

    De Silva, T; Uneri, A; Ketcha, M D; Reaungamornrat, S; Kleinszig, G; Vogt, S; Aygun, N; Lo, S-F; Wolinsky, J-P; Siewerdsen, J H

    2016-04-21

    In image-guided spine surgery, robust three-dimensional to two-dimensional (3D-2D) registration of preoperative computed tomography (CT) and intraoperative radiographs can be challenged by the image content mismatch associated with the presence of surgical instrumentation and implants as well as soft-tissue resection or deformation. This work investigates image similarity metrics in 3D-2D registration offering improved robustness against mismatch, thereby improving performance and reducing or eliminating the need for manual masking. The performance of four gradient-based image similarity metrics (gradient information (GI), gradient correlation (GC), gradient information with linear scaling (GS), and gradient orientation (GO)) with a multi-start optimization strategy was evaluated in an institutional review board-approved retrospective clinical study using 51 preoperative CT images and 115 intraoperative mobile radiographs. Registrations were tested with and without polygonal masks as a function of the number of multistarts employed during optimization. Registration accuracy was evaluated in terms of the projection distance error (PDE) and assessment of failure modes (PDE  >  30 mm) that could impede reliable vertebral level localization. With manual polygonal masking and 200 multistarts, the GC and GO metrics exhibited robust performance with 0% gross failures and median PDE  <  6.4 mm (±4.4 mm interquartile range (IQR)) and a median runtime of 84 s (plus upwards of 1-2 min for manual masking). Excluding manual polygonal masks and decreasing the number of multistarts to 50 caused the GC-based registration to fail at a rate of  >14%; however, GO maintained robustness with a 0% gross failure rate. Overall, the GI, GC, and GS metrics were susceptible to registration errors associated with content mismatch, but GO provided robust registration (median PDE  =  5.5 mm, 2.6 mm IQR) without manual masking and with an improved runtime (29.3 s). The GO metric improved the registration accuracy and robustness in the presence of strong image content mismatch. This capability could offer valuable assistance and decision support in spine level localization in a manner consistent with clinical workflow. PMID:26992245

  13. Reconstruction of 3D lung models from 2D planning data sets for Hodgkin's lymphoma patients using combined deformable image registration and navigator channels

    SciTech Connect

    Ng, Angela; Nguyen, Thao-Nguyen; Moseley, Joanne L.; Hodgson, David C.; Sharpe, Michael B.; Brock, Kristy K.

    2010-03-15

    Purpose: Late complications (cardiac toxicities, secondary lung, and breast cancer) remain a significant concern in the radiation treatment of Hodgkin's lymphoma (HL). To address this issue, predictive dose-risk models could potentially be used to estimate radiotherapy-related late toxicities. This study investigates the use of deformable image registration (DIR) and navigator channels (NCs) to reconstruct 3D lung models from 2D radiographic planning images, in order to retrospectively calculate the treatment dose exposure to HL patients treated with 2D planning, which are now experiencing late effects. Methods: Three-dimensional planning CT images of 52 current HL patients were acquired. 12 image sets were used to construct a male and a female population lung model. 23 ''Reference'' images were used to generate lung deformation adaptation templates, constructed by deforming the population model into each patient-specific lung geometry using a biomechanical-based DIR algorithm, MORFEUS. 17 ''Test'' patients were used to test the accuracy of the reconstruction technique by adapting existing templates using 2D digitally reconstructed radiographs. The adaptation process included three steps. First, a Reference patient was matched to a Test patient by thorax measurements. Second, four NCs (small regions of interest) were placed on the lung boundary to calculate 1D differences in lung edges. Third, the Reference lung model was adapted to the Test patient's lung using the 1D edge differences. The Reference-adapted Test model was then compared to the 3D lung contours of the actual Test patient by computing their percentage volume overlap (POL) and Dice coefficient. Results: The average percentage overlapping volumes and Dice coefficient expressed as a percentage between the adapted and actual Test models were found to be 89.2{+-}3.9% (Right lung=88.8%; Left lung=89.6%) and 89.3{+-}2.7% (Right=88.5%; Left=90.2%), respectively. Paired T-tests demonstrated that the volumetric reconstruction method made a statistically significant improvement to the population lung model shape (p<0.05). The error in the results were also comparable to the volume overlap difference observed between inhale and exhale lung volumes during free-breathing respiratory motion (POL:p=0.43; Dice:p=0.20), which implies that the accuracies of the reconstruction method are within breathing constraints and would not be the confining factor in estimating normal tissue dose exposure. Conclusions: The result findings show that the DIR-NC technique can achieve a high degree of reconstruction accuracy, and could be useful in approximating 3D dosimetric representations of historical 2D treatment. In turn, this could provide a better understanding of the biophysical relationship between dose-volume exposure and late term radiotherapy effects.

  14. 2D-1H proton magnetic resonance spectroscopic imaging study on brain metabolite alterations in patients with diabetic hypertension.

    PubMed

    Cao, Zhen; Ye, Bi-Di; Shen, Zhi-Wei; Cheng, Xiao-Fang; Yang, Zhong-Xian; Liu, Yan-Yan; Wu, Ren-Hua; Geng, Kuan; Xiao, Ye-Yu

    2015-06-01

    The aim of the present study was to investigate the possible metabolic alterations in the frontal cortex and parietal white matter in patients with diabetic hypertension (DHT) using proton magnetic resonance (MR) spectroscopic imaging. A total of 33 DHT patients and 30 healthy control subjects aged between 45 and 75 were included in the present study. All subjects were right‑handed. The spectroscopy data were collected using a GE Healthcare 1.5T MR scanner. The multi‑voxels were located in the semioval center (repetition time/echo time=1,500 ms/35 ms). The area of interest was 8x10x2 cm in volume and contained the two sides of the frontal cortex and the parietal white matter. The spectra data were processed using SAGE software. The ratios of brain metabolite concentrations, particularly for N‑acetylaspartate (NAA)/creatine (Cr) and Choline (Cho)/Cr were calculated and analyzed. Statistical analyses were performed using SPSS 17.0. The NAA/Cr ratio of the bilateral prefrontal cortex of the DHT group was significantly lower than that of the control group (left t=‑7.854, P=0.000 and right t=‑5.787, P=0.000), The Cho/Cr ratio was also much lower than the control group (left t=2.422, P=0.024 and right t=2.920, P=0.007). NAA/Cr ratio of the left parietal white matter of the DHT group was extremely lower than that of the control group (t=‑4.199, P=0.000). Therefore, DHT may result in metabolic disorders in the frontal cortex and parietal white matter but the metabolic alterations are different in various regions of the brain. The alteration in cerebral metabolism is associated with diabetes and hypertension. The ratios of NAA/Cr and Cho/Cr are potential metabolic markers for the brain damage induced by DHT. PMID:25652580

  15. Near-infrared (NIR) imaging analysis of polylactic acid (PLA) nanocomposite by multiple-perturbation two-dimensional (2D) correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Shinzawa, Hideyuki; Murakami, Takurou N.; Nishida, Masakazu; Kanematsu, Wataru; Noda, Isao

    2014-07-01

    Multiple-perturbation two-dimensional (2D) correlation spectroscopy was applied to sets of near-infrared (NIR) imaging data of polylactic acid (PLA) nanocomposite samples undergoing UV degradation. Incorporation of clay nanoparticles substantially lowers the surface free energy barrier for the nucleation of PLA and eventually increases the frequency of the spontaneous nucleation of PLA crystals. Thus, when exposed to external stimuli such as UV light, PLA nanocomposite may show different structure alternation depending on the clay dispersion. Multiple-perturbation 2D correlation analysis of the PLA nanocomposite samples revealed different spatial variation between crystalline and amorphous structure of PLA, and the phenomenon especially becomes acute in the region where the clay particles are coagulated. The incorporation of the clay leads to the cleavage-induced crystallization of PLA when the sample is subjected to the UV light. The additional development of the ordered crystalline structure then works favorably to restrict the initial degradation of the polymer, providing the delay in the weight loss of the PLA.

  16. Diversity of atrial local Ca2+ signalling: evidence from 2-D confocal imaging in Ca2+-buffered rat atrial myocytes.

    PubMed

    Woo, Sun-Hee; Cleemann, Lars; Morad, Martin

    2005-09-15

    Atrial myocytes, lacking t-tubules, have two functionally separate groups of ryanodine receptors (RyRs): those at the periphery colocalized with dihydropyridine receptors (DHPRs), and those at the cell interior not associated with DHPRs. We have previously shown that the Ca(2+) current (I(Ca))-gated central Ca(2+) release has a fast component that is followed by a slower and delayed rising phase. The mechanisms that regulate the central Ca(2+) releases remain poorly understood. The fast central release component is highly resistant to dialysed Ca(2+) buffers, while the slower, delayed component is completely suppressed by such exogenous buffers. Here we used dialysis of Ca(2+) buffers (EGTA) into voltage-clamped rat atrial myocytes to isolate the fast component of central Ca(2+) release and examine its properties using rapid (240 Hz) two-dimensional confocal Ca(2+) imaging. We found two populations of rat atrial myocytes with respect to the ratio of central to peripheral Ca(2+) release (R(c/p)). In one population ('group 1', approximately 60% of cells), R(c/p) converged on 0.2, while in another population ('group 2', approximately 40%), R(c/p) had a Gaussian distribution with a mean value of 0.625. The fast central release component of group 2 cells appeared to result from in-focus Ca(2+) sparks on activation of I(Ca). In group 1 cells intracellular membranes associated with t-tubular structures were never seen using short exposures to membrane dyes. In most of the group 2 cells, a faint intracellular membrane staining was observed. Quantification of caffeine-releasable Ca(2+) pools consistently showed larger central Ca(2+) stores in group 2 and larger peripheral stores in group 1 cells. The R(c/p) was larger at more positive and negative voltages in group 1 cells. In contrast, in group 2 cells, the R(c/p) was constant at all voltages. In group 1 cells the gain of peripheral Ca(2+) release sites (Delta[Ca(2+)]/I(Ca)) was larger at -30 than at +20 mV, but significantly dampened at the central sites. On the other hand, the gains of peripheral and central Ca(2+) releases in group 2 cells showed no voltage dependence. Surprisingly, the voltage dependence of the fast central release component was bell-shaped and similar to that of I(Ca) in both cell groups. Removal of extracellular Ca(2+) or application of Ni(2+) (5 mM) suppressed equally I(Ca) and Ca(2+) release from the central release sites at +60 mV. Depolarization to +100 mV, where I(Ca) is absent and the Na(+)-Ca(2+) exchanger (NCX) acts in reverse mode, did not trigger the fast central Ca(2+) releases in either group, but brief reduction of [Na(+)](o) to levels equivalent to [Na(+)](i) facilitated fast peripheral and central Ca(2+) releases in group 2 myocytes, but not in group 1 myocytes. In group 2 cells, long-lasting (> 1 min) exposures to caffeine (10 mM) or ryanodine (20 microM) significantly suppressed I(Ca)-triggered central and peripheral Ca(2+) releases. Our data suggest significant diversity of local Ca(2+) signalling in rat atrial myocytes. In one group, I(Ca)-triggered peripheral Ca(2+) release propagates into the interior triggering central Ca(2+) release with significant delay. In a second group of myocytes I(Ca) triggers a significant number of central sites as rapidly and effectively as the peripheral sites, thereby producing more synchronized Ca(2+) releases throughout the myocytes. The possible presence of vestigial t-tubules and larger Ca(2+) content of central sarcoplasmic reticulum (SR) in group 2 cells may be responsible for the rapid and strong activation of central release of Ca(2+) in this subset of atrial myocytes. PMID:16020459

  17. Temperature uncertainty of IR thermal imager calibration

    NASA Astrophysics Data System (ADS)

    Peacock, G. Raymond

    2006-04-01

    Widening uses of Infrared Thermal Imagers, many having temperature measurement indication, calls into question the accuracy of indicated temperature values. The answer is not simple since there are two separate and distinct areas that impact any measurement, calibration and actual use. The two areas can be treated separately, since they are, in fact, separate conditions of instrument use, one ideally under well controlled and highly repeatable conditions. This report covers the topics associated with calibration. First, there is a generic review of typical Infrared Radiation Thermometer measuring instrument methods. Next, practices reported in the literature for IR Thermal Imagers are presented. Then these are compared with actual procedures and practices used by imager manufacturers. This last information was gathered through voluntary responses to a survey of equipment makers.

  18. The Feasibility of Using High Resolution 2D Electrical Resistivity Imaging (ERI) for characterize the possible hydraulic boundaries along the western foothill of Bagua-Douliu Hills, Taiwan

    NASA Astrophysics Data System (ADS)

    Chang, S.; Chang, P.; Wu, Y.; Chen, J.; Huang, C.; Wang, Y.; Chen, W.

    2011-12-01

    In the study we try to characteristize the hydraulic boundary that separates the Pleistocene Toukeshan Formation from the Holocene sediments with Electrical Resistivity Imaging (ERI) method near the Bizetou Pass of the Choushui River. Comparing 2D Electrical resistivity imaging (ERI) with water level logs and core data from observation wells, we attempted to map the distribution of the shallow groundwater surfaces and the composition variations of the shallow unconfined aquifer from upper to lower fan across the Bizetou Pass. We found that the shallow groundwater surface drops sudenly from about 110m to 70 m after passing the Bizetou Pass from observation wells at the east and west side of the Pass and with about 3 km apart. The inverted resistivity images also show that the hydraulic gradient estimated from the resistivity images is getting larger to about 7% near the Bizetou Pass and then becoming less than 3% in the west the Pass. In addition, we found a significant change from about 1500 ohm-m to 500 ohm-m in the unconfined aquifer after passing the Bizetou Pass from the upstream side. The high resistivity value (about 1500 ohm-m) in the east of Bizetou Pass may represent the compacted Pleistocene Tokeshan sand and gravel layers, and the relatively low resistivity value (about 500 ohm-m) in the west of Bizetou Pass was the loose Holocene alluvium sediments. Since the previous study shows that the Changhua fault is not outcropped at the ground surface, our findings imply that the hydraulic boundary may be due to the less permeable Toukoshan Formation. To confirm this, the future work will extend the study area in North-South direction between Changhua County and Yunlin County.

  19. Imaging the Ferron Member of the Mancos Shale formation using reprocessed high-resolution 2-D seismic reflection data: Emery County, Utah

    USGS Publications Warehouse

    Taylor, D.J.

    2003-01-01

    Late in 1982 and early in 1983, Arco Exploration contracted with Rocky Mountain Geophysical to acquired four high-resolution 2-D multichannel seismic reflection lines in Emery County, Utah. The primary goal in acquiring this data was an attempt to image the Ferron Member of the Upper Cretaceous Mancos Shale. Design of the high-resolution 2-D seismic reflection data acquisition used both a short geophone group interval and a short sample interval. An explosive energy source was used which provided an input pulse with broad frequency content and higher frequencies than typical non-explosive Vibroseis?? sources. Reflections produced by using this high-frequency energy source when sampled at a short interval are usually able to resolve shallow horizons that are relatively thin compared to those that can be resolved using more typical oil and gas exploration seismic reflection methods.The U.S. Geological Survey-Energy Resources Program, Geophysical Processing Group used the processing sequence originally applied by Arco in 1984 as a guide and experimented with processing steps applied in a different order using slightly different parameters in an effort to improve imaging the Ferron Member horizon. As with the Arco processed data there are sections along all four seismic lines where the data quality cannot be improved upon, and in fact the data quality is so poor that the Ferron horizon cannot be imaged at all.Interpretation of the seismic and core hole data indicates that the Ferron Member in the study area represent a deltaic sequence including delta front, lower delta plain, and upper delta plain environments. Correlating the depositional environments for the Ferron Member as indicated in the core holes with the thickness of Ferron Member suggests the presence of a delta lobe running from the northwest to the southeast through the study area. The presence of a deltaic channel system within the delta lobe complex might prove to be an interesting conventional exploration target along with the coal-bed methane production already proven in the area. ?? 2003 Elsevier B.V. All rights reserved.

  20. Three-Dimensional Mapping of Soil Chemical Characteristics at Micrometric Scale by Combining 2D SEM-EDX Data and 3D X-Ray CT Images

    PubMed Central

    Hapca, Simona; Baveye, Philippe C.; Wilson, Clare; Lark, Richard Murray; Otten, Wilfred

    2015-01-01

    There is currently a significant need to improve our understanding of the factors that control a number of critical soil processes by integrating physical, chemical and biological measurements on soils at microscopic scales to help produce 3D maps of the related properties. Because of technological limitations, most chemical and biological measurements can be carried out only on exposed soil surfaces or 2-dimensional cuts through soil samples. Methods need to be developed to produce 3D maps of soil properties based on spatial sequences of 2D maps. In this general context, the objective of the research described here was to develop a method to generate 3D maps of soil chemical properties at the microscale by combining 2D SEM-EDX data with 3D X-ray computed tomography images. A statistical approach using the regression tree method and ordinary kriging applied to the residuals was developed and applied to predict the 3D spatial distribution of carbon, silicon, iron, and oxygen at the microscale. The spatial correlation between the X-ray grayscale intensities and the chemical maps made it possible to use a regression-tree model as an initial step to predict the 3D chemical composition. For chemical elements, e.g., iron, that are sparsely distributed in a soil sample, the regression-tree model provides a good prediction, explaining as much as 90% of the variability in some of the data. However, for chemical elements that are more homogenously distributed, such as carbon, silicon, or oxygen, the additional kriging of the regression tree residuals improved significantly the prediction with an increase in the R2 value from 0.221 to 0.324 for carbon, 0.312 to 0.423 for silicon, and 0.218 to 0.374 for oxygen, respectively. The present research develops for the first time an integrated experimental and theoretical framework, which combines geostatistical methods with imaging techniques to unveil the 3-D chemical structure of soil at very fine scales. The methodology presented in this study can be easily adapted and applied to other types of data such as bacterial or fungal population densities for the 3D characterization of microbial distribution. PMID:26372473

  1. Three-Dimensional Mapping of Soil Chemical Characteristics at Micrometric Scale by Combining 2D SEM-EDX Data and 3D X-Ray CT Images.

    PubMed

    Hapca, Simona; Baveye, Philippe C; Wilson, Clare; Lark, Richard Murray; Otten, Wilfred

    2015-01-01

    There is currently a significant need to improve our understanding of the factors that control a number of critical soil processes by integrating physical, chemical and biological measurements on soils at microscopic scales to help produce 3D maps of the related properties. Because of technological limitations, most chemical and biological measurements can be carried out only on exposed soil surfaces or 2-dimensional cuts through soil samples. Methods need to be developed to produce 3D maps of soil properties based on spatial sequences of 2D maps. In this general context, the objective of the research described here was to develop a method to generate 3D maps of soil chemical properties at the microscale by combining 2D SEM-EDX data with 3D X-ray computed tomography images. A statistical approach using the regression tree method and ordinary kriging applied to the residuals was developed and applied to predict the 3D spatial distribution of carbon, silicon, iron, and oxygen at the microscale. The spatial correlation between the X-ray grayscale intensities and the chemical maps made it possible to use a regression-tree model as an initial step to predict the 3D chemical composition. For chemical elements, e.g., iron, that are sparsely distributed in a soil sample, the regression-tree model provides a good prediction, explaining as much as 90% of the variability in some of the data. However, for chemical elements that are more homogenously distributed, such as carbon, silicon, or oxygen, the additional kriging of the regression tree residuals improved significantly the prediction with an increase in the R2 value from 0.221 to 0.324 for carbon, 0.312 to 0.423 for silicon, and 0.218 to 0.374 for oxygen, respectively. The present research develops for the first time an integrated experimental and theoretical framework, which combines geostatistical methods with imaging techniques to unveil the 3-D chemical structure of soil at very fine scales. The methodology presented in this study can be easily adapted and applied to other types of data such as bacterial or fungal population densities for the 3D characterization of microbial distribution. PMID:26372473

  2. A novel material detection algorithm based on 2D GMM-based power density function and image detail addition scheme in dual energy X-ray images.

    PubMed

    Pourghassem, Hossein

    2012-01-01

    Material detection is a vital need in dual energy X-ray luggage inspection systems at security of airport and strategic places. In this paper, a novel material detection algorithm based on statistical trainable models using 2-Dimensional power density function (PDF) of three material categories in dual energy X-ray images is proposed. In this algorithm, the PDF of each material category as a statistical model is estimated from transmission measurement values of low and high energy X-ray images by Gaussian Mixture Models (GMM). Material label of each pixel of object is determined based on dependency probability of its transmission measurement values in the low and high energy to PDF of three material categories (metallic, organic and mixed materials). The performance of material detection algorithm is improved by a maximum voting scheme in a neighborhood of image as a post-processing stage. Using two background removing and denoising stages, high and low energy X-ray images are enhanced as a pre-processing procedure. For improving the discrimination capability of the proposed material detection algorithm, the details of the low and high energy X-ray images are added to constructed color image which includes three colors (orange, blue and green) for representing the organic, metallic and mixed materials. The proposed algorithm is evaluated on real images that had been captured from a commercial dual energy X-ray luggage inspection system. The obtained results show that the proposed algorithm is effective and operative in detection of the metallic, organic and mixed materials with acceptable accuracy. PMID:22635176

  3. High-Resolution 3-T Endorectal Prostate MRI: A Multireader Study of Radiologist Preference and Perceived Interpretive Quality of 2D and 3D T2-Weighted Fast Spin-Echo MR Images

    PubMed Central

    Westphalen, Antonio C.; Noworolski, Susan M.; Harisinghani, Mukesh; Jhaveri, Kartik S.; Raman, Steve S.; Rosenkrantz, Andrew B.; Wang, Zhen J.; Zagoria, Ronald J.; Kurhanewicz, John

    2016-01-01

    OBJECTIVE The goal of this study was to compare the perceived quality of 3-T axial T2-weighted high-resolution 2D and high-resolution 3D fast spin-echo (FSE) endorectal MR images of the prostate. MATERIALS AND METHODS Six radiologists independently reviewed paired 3-T axial T2-weighted high-resolution 2D and 3D FSE endorectal MR images of the prostates of 85 men in two sessions. In the first session (n = 85), each reader selected his or her preferred images; in the second session (n = 28), they determined their confidence in tumor identification and compared the depiction of the prostatic anatomy, tumor conspicuity, and subjective intrinsic image quality of images. A meta-analysis using a random-effects model, logistic regression, and the paired Wilcoxon rank-sum test were used for statistical analyses. RESULTS Three readers preferred the 2D acquisition (67–89%), and the other three preferred the 3D images (70–80%). The option for one of the techniques was not associated with any of the predictor variables. The 2D FSE images were significantly sharper than 3D FSE (p < 0.001) and significantly more likely to exhibit other (nonmotion) artifacts (p = 0.002). No other statistically significant differences were found. CONCLUSION Our results suggest that there are strong individual preferences for the 2D or 3D FSE MR images, but there was a wide variability among radiologists. There were differences in image quality (image sharpness and presence of artifacts not related to motion) but not in the sequences’ ability to delineate the glandular anatomy and depict a cancerous tumor. PMID:26491891

  4. Self-calibration of cone-beam CT geometry using 3D-2D image registration: development and application to tasked-based imaging with a robotic C-arm

    NASA Astrophysics Data System (ADS)

    Ouadah, S.; Stayman, J. W.; Gang, G.; Uneri, A.; Ehtiati, T.; Siewerdsen, J. H.

    2015-03-01

    Purpose: Robotic C-arm systems are capable of general noncircular orbits whose trajectories can be driven by the particular imaging task. However obtaining accurate calibrations for reconstruction in such geometries can be a challenging problem. This work proposes a method to perform a unique geometric calibration of an arbitrary C-arm orbit by registering 2D projections to a previously acquired 3D image to determine the transformation parameters representing the system geometry. Methods: Experiments involved a cone-beam CT (CBCT) bench system, a robotic C-arm, and three phantoms. A robust 3D-2D registration process was used to compute the 9 degree of freedom (DOF) transformation between each projection and an existing 3D image by maximizing normalized gradient information with a digitally reconstructed radiograph (DRR) of the 3D volume. The quality of the resulting "self-calibration" was evaluated in terms of the agreement with an established calibration method using a BB phantom as well as image quality in the resulting CBCT reconstruction. Results: The self-calibration yielded CBCT images without significant difference in spatial resolution from the standard ("true") calibration methods (p-value >0.05 for all three phantoms), and the differences between CBCT images reconstructed using the "self" and "true" calibration methods were on the order of 10-3 mm-1. Maximum error in magnification was 3.2%, and back-projection ray placement was within 0.5 mm. Conclusion: The proposed geometric "self" calibration provides a means for 3D imaging on general noncircular orbits in CBCT systems for which a geometric calibration is either not available or not reproducible. The method forms the basis of advanced "task-based" 3D imaging methods now in development for robotic C-arms.

  5. Spectrally edited 2D 13Csbnd 13C NMR spectra without diagonal ridge for characterizing 13C-enriched low-temperature carbon materials

    NASA Astrophysics Data System (ADS)

    Johnson, Robert L.; Anderson, Jason M.; Shanks, Brent H.; Fang, Xiaowen; Hong, Mei; Schmidt-Rohr, Klaus

    2013-09-01

    Two robust combinations of spectral editing techniques with 2D 13Csbnd 13C NMR have been developed for characterizing the aromatic components of 13C-enriched low-temperature carbon materials. One method (exchange with protonated and nonprotonated spectral editing, EXPANSE) selects cross peaks of protonated and nearby nonprotonated carbons, while the other technique, dipolar-dephased double-quantum/single-quantum (DQ/SQ) NMR, selects signals of bonded nonprotonated carbons. Both spectra are free of a diagonal ridge, which has many advantages: Cross peaks on the diagonal or of small intensity can be detected, and residual spinning sidebands or truncation artifacts associated with the diagonal ridge are avoided. In the DQ/SQ experiment, dipolar dephasing of the double-quantum coherence removes protonated-carbon signals; this approach also eliminates the need for high-power proton decoupling. The initial magnetization is generated with minimal fluctuation by combining direct polarization, cross polarization, and equilibration by 13C spin diffusion. The dipolar dephased DQ/SQ spectrum shows signals from all linkages between aromatic rings, including a distinctive peak from polycondensed aromatics. In EXPANSE NMR, signals of protonated carbons are selected in the first spectral dimension by short cross polarization combined with dipolar dephasing difference. This removes ambiguities of peak assignment to overlapping signals of nonprotonated and protonated aromatic carbons, e.g. near 125 ppm. Spin diffusion is enhanced by dipolar-assisted rotational resonance. Before detection, Csbnd H dipolar dephasing by gated decoupling is applied, which selects signals of nonprotonated carbons. Thus, only cross peaks due to magnetization originating from protonated C and ending on nearby nonprotonated C are retained. Combined with the chemical shifts deduced from the cross-peak position, this double spectral editing defines the bonding environment of aromatic, COO, and Cdbnd O carbons, which is particularly useful for identifying furan and arene rings. The Cdbnd O carbons, whose chemical shifts vary strongly (between 212 and 165 ppm) and systematically depend on their two bonding partners, show particularly informative cross peaks, given that one bonding partner is defined by the other frequency coordinate of the cross peak. The new techniques and the information content of the resulting spectra are validated on sulfuric-acid treated low-temperature carbon materials and on products of the Maillard reaction. The crucial need for spectral editing for correct peak assignment is demonstrated in an example.

  6. Graph Structure-Based Simultaneous Localization and Mapping Using a Hybrid Method of 2D Laser Scan and Monocular Camera Image in Environments with Laser Scan Ambiguity

    PubMed Central

    Oh, Taekjun; Lee, Donghwa; Kim, Hyungjin; Myung, Hyun

    2015-01-01

    Localization is an essential issue for robot navigation, allowing the robot to perform tasks autonomously. However, in environments with laser scan ambiguity, such as long corridors, the conventional SLAM (simultaneous localization and mapping) algorithms exploiting a laser scanner may not estimate the robot pose robustly. To resolve this problem, we propose a novel localization approach based on a hybrid method incorporating a 2D laser scanner and a monocular camera in the framework of a graph structure-based SLAM. 3D coordinates of image feature points are acquired through the hybrid method, with the assumption that the wall is normal to the ground and vertically flat. However, this assumption can be relieved, because the subsequent feature matching process rejects the outliers on an inclined or non-flat wall. Through graph optimization with constraints generated by the hybrid method, the final robot pose is estimated. To verify the effectiveness of the proposed method, real experiments were conducted in an indoor environment with a long corridor. The experimental results were compared with those of the conventional GMappingapproach. The results demonstrate that it is possible to localize the robot in environments with laser scan ambiguity in real time, and the performance of the proposed method is superior to that of the conventional approach. PMID:26151203

  7. Preliminary evidence for white matter metabolite differences in marijuana dependent young men using 2D J-resolved magnetic resonance spectroscopic imaging at 4 Tesla

    PubMed Central

    Silveri, Marisa M.; Jensen, J. Eric; Rosso, Isabelle M.; Sneider, Jennifer T.; Yurgelun-Todd, Deborah A.

    2010-01-01

    Chronic marijuana (MRJ) use is associated with altered cognition and mood state, altered brain metabolites, functional and structural brain changes. The objective of this study was to apply proton magnetic resonance spectroscopic imaging (MRSI) to compare proton metabolite levels in 15 young men with MRJ-dependence and 11 healthy non-using (NU) young men. Spectra were acquired at 4.0 Tesla using 2D J-resolved MRSI to resolve coupled resonances in J-space and to quantify the entire J-coupled spectral surface of metabolites from voxels containing basal ganglia and thalamus, temporal and parietal lobe, and occipital white and gray matter. This method permitted investigation of high-quality spectra for regression analyses to examine metabolites relative to tissue type. Distribution of myo-inositol (mI)/creatine (Cr) was altered in the MRJ group whereas the NU group exhibited higher mI/Cr in WM than GM, this pattern was not observed in MRJ subjects. Significant relationships observed between global mI/Cr and distribution in WM, and self-reported impulsivity and mood symptoms were also unique between MRJ and NU groups. These preliminary findings suggest that mI, and distribution of this glial metabolite in WM, is altered by MRJ use and is associated with behavioral and affective features reported by young MRJ-dependent men. PMID:21334181

  8. Graph Structure-Based Simultaneous Localization and Mapping Using a Hybrid Method of 2D Laser Scan and Monocular Camera Image in Environments with Laser Scan Ambiguity.

    PubMed

    Oh, Taekjun; Lee, Donghwa; Kim, Hyungjin; Myung, Hyun

    2015-01-01

    Localization is an essential issue for robot navigation, allowing the robot to perform tasks autonomously. However, in environments with laser scan ambiguity, such as long corridors, the conventional SLAM (simultaneous localization and mapping) algorithms exploiting a laser scanner may not estimate the robot pose robustly. To resolve this problem, we propose a novel localization approach based on a hybrid method incorporating a 2D laser scanner and a monocular camera in the framework of a graph structure-based SLAM. 3D coordinates of image feature points are acquired through the hybrid method, with the assumption that the wall is normal to the ground and vertically flat. However, this assumption can be relieved, because the subsequent feature matching process rejects the outliers on an inclined or non-flat wall. Through graph optimization with constraints generated by the hybrid method, the final robot pose is estimated. To verify the effectiveness of the proposed method, real experiments were conducted in an indoor environment with a long corridor. The experimental results were compared with those of the conventional GMappingapproach. The results demonstrate that it is possible to localize the robot in environments with laser scan ambiguity in real time, and the performance of the proposed method is superior to that of the conventional approach. PMID:26151203

  9. Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2-D time-lapse surface electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Wallin, E. L.; Johnson, T. C.; Greenwood, W. J.; Zachara, J. M.

    2013-03-01

    The Hanford 300 Area is located adjacent to the Columbia River in south-central Washington State, USA, and was a former site for nuclear fuel processing operations. Waste disposal practices resulted in persistent unsaturated zone and groundwater contamination, the primary contaminant of concern being uranium. Uranium behavior at the site is intimately linked with river stage driven groundwater-river water exchange such that understanding the nature of river water intrusion into the 300 Area is critical for predicting uranium desorption and transport. In this paper, we use 2-D surface-based time-lapse electrical resistivity tomography (ERT) to image the inland intrusion of river water during high stage conditions. We inverted approximately 1200 data sets (400 per line over three lines) using high performance computing resources to produce a time-lapse sequence of changes in bulk conductivity caused by river water intrusion during the 2011 spring runoff cycle over approximately 125 days. To invert the data, we use an image differencing approach that does not require regularization in the time dimension, enabling the inversion to accommodate the sharp, time varying contrasts in conductivity imposed by the moving water table. The resulting time series for each mesh element was then analyzed using common time series analysis to reveal the timing and location of river water intrusion beneath each line. The results reveal nonuniform flows characterized by preferred flow zones where river water enters and exits quickly with stage increase and decrease, and low permeability zones with broader bulk conductivity "break through" curves and longer river water residence times.

  10. JPEG2000 3D compression vs. 2D compression: an assessment of artifact amount and computing time in compressing thin-section abdomen CT images.

    PubMed

    Kim, Bohyoung; Lee, Kyoung Ho; Kim, Kil Joong; Richter, Thomas; Kang, Heung-Sik; Kim, So Yeon; Kim, Young Hoon; Seo, Jinwook

    2009-03-01

    To assess the advantages of the Joint Photographic Experts Group (JPEG)2000 3D (part 2) over JPEG2000 in compressing thin-section abdomen CT data sets, 60 thin-section (0.67 mm) scans from 35 males and 25 females, ranging from 23 to 95 years of age (mean, 58 years), were compressed reversibly (as a negative control) and irreversibly to 4:1, 6:1, 8:1, 10:1, and 12:1 using JPEG2000 3D and JPEG2000 algorithms. Encoding and decoding times and peak signal-to-noise ratios (PSNRs) were measured. For 60 (one image per scan) representative sections containing abnormalities, three radiologists independently compared original and compressed images and graded compression artifacts as 0 (none, indistinguishable), 1 (barely perceptible), 2 (subtle), or 3 (significant). According to pooled radiologists' responses, the range of visually lossless threshold (VLT, the highest compression ratio at which a compressed image is indistinguishable from its original) was determined as one of <4:1, 4:1-6:1, 6:1-8:1, 8:1-10:1, 10:1-12:1, and >12:1. Wilcoxon signed rank tests and exact tests for paired proportions were used for the comparisons between the two compressions. At each irreversible compression ratio, compared to JPEG2000, JPEG2000 3D required two- or threefold greater computing times (p < 0.001) and introduced less artifacts in terms of PSNR (p <0.001) and the grade (p < 0.02 at 6:1 or higher) and the presence of perceived artifacts (p <0.008, at 6:1 for all readers and at 8:1 for two readers). According to PSNR and readers' responses, 6:1 and 8:1 JPEG2000 3D compressions showed more artifacts than 4:1 and 6:1 JPEG2000 compressions, respectively, and 10:1 and 12:1 JPEG2000 3D compressions showed similar artifacts to those of 8:1 and 10:1 JPEG2000 compressions, respectively. The determined VLT range was higher for JPEG2000 3D than for JPEG2000 (p < 0.001): the 3D compression showed the VLT ranges of 4:1-6:1, 6:1-8:1, and 8:1-10:1 for 24 (40%), 30 (50%), and 6 (10%) of the 60 original images, respectively, while the 2D compression showed the VLT ranges of <4:1, 4:1-6:1, and 6:1-8:1 for 1 (1.7%), 40 (66.7%), and 19 (31.6%) images, respectively. Compared to JPEG2000, JPEG2000 3D increased the VLT range in 23 of the 60 original images by one (n=22) or two ranges (n=1), while the remaining 37 images had the same VLT range between the two compressions. In conclusion, compared to JPEG2000 compression, JPEG2000 3D compression yields less artifacts in compressing thin-section abdomen CT images but requires significantly greater computing times. For the tested data set compressed to the range from 4:1 to 12:1, JPEG2000 3D could increase compression level reasonably (by 2 or less in terms of compression ratio) compared to JPEG2000 for the same amount of artifacts. PMID:19378744

  11. Stream Temperature Estimation From Thermal Infrared Images

    NASA Astrophysics Data System (ADS)

    Handcock, R. N.; Kay, J. E.; Gillespie, A.; Naveh, N.; Cherkauer, K. A.; Burges, S. J.; Booth, D. B.

    2001-12-01

    Stream temperature is an important water quality indicator in the Pacific Northwest where endangered fish populations are sensitive to elevated water temperature. Cold water refugia are essential for the survival of threatened salmon when events such as the removal of riparian vegetation result in elevated stream temperatures. Regional assessment of stream temperatures is limited by sparse sampling of temperatures in both space and time. If critical watersheds are to be properly managed it is necessary to have spatially extensive temperature measurements of known accuracy. Remotely sensed thermal infrared (TIR) imagery can be used to derive spatially distributed estimates of the skin temperature (top 100 nm) of streams. TIR imagery has long been used to estimate skin temperatures of the ocean, where split-window techniques have been used to compensate for atmospheric affects. Streams are a more complex environment because 1) most are unresolved in typical TIR images, and 2) the near-bank environment of stream corridors may consist of tall trees or hot rocks and soils that irradiate the stream surface. As well as compensating for atmospheric effects, key problems to solve in estimating stream temperatures include both subpixel unmixing and multiple scattering. Additionally, fine resolution characteristics of the stream surface such as evaporative cooling due to wind, and water surface roughness, will effect measurements of radiant skin temperatures with TIR devices. We apply these corrections across the Green River and Yakima River watersheds in Washington State to assess the accuracy of remotely sensed stream surface temperature estimates made using fine resolution TIR imagery from a ground-based sensor (FLIR), medium resolution data from the airborne MASTER sensor, and coarse-resolution data from the Terra-ASTER satellite. We use linear spectral mixture analysis to isolate the fraction of land-leaving radiance originating from unresolved streams. To compensate the data for atmospheric effects we combine radiosonde profiles with a physically based radiative transfer model (MODTRAN) and an in-scene relative correction adapted from the ISAC algorithm. Laboratory values for water emissivities are used as a baseline estimate of stream emissivities. Emitted radiance reflected by trees in the stream near-bank environment is estimated from the height and canopy temperature, using a radiosity model.

  12. Infrared image processing devoted to thermal non-contact characterization-Applications to Non-Destructive Evaluation, Microfluidics and 2D source term distribution for multispectral tomography

    NASA Astrophysics Data System (ADS)

    Batsale, Jean-Christophe; Pradere, Christophe

    2015-11-01

    The cost of IR cameras is more and more decreasing. Beyond the preliminary calibration step and the global instrumentation, the infrared image processing is then one of the key step for achieving in very broad domains. Generally the IR images are coming from the transient temperature field related to the emission of a black surface in response to an external or internal heating (active IR thermography). The first applications were devoted to the so called thermal Non-Destructive Evaluation methods by considering a thin sample and 1D transient heat diffusion through the sample (transverse diffusion). With simplified assumptions related to the transverse diffusion, the in-plane diffusion and transport phenomena can be also considered. A general equation can be applied in order to balance the heat transfer at the pixel scale or between groups of pixels in order to estimate several fields of thermophysical properties (heterogeneous field of in-plane diffusivity, flow distributions, source terms). There is a lot of possible strategies to process the space and time distributed big amount of data (previous integral transformation of the images, compression, elimination of the non useful areas...), generally based on the necessity to analyse the derivative versus space and time of the temperature field. Several illustrative examples related to the Non-Destructive Evaluation of heterogeneous solids, the thermal characterization of chemical reactions in microfluidic channels and the design of systems for multispectral tomography, will be presented.

  13. Cortical Dopamine D2/D3 Receptors Are a Common Site of Action for Antipsychotic Drugs—An Original Patient Data Meta-analysis of the SPECT and PET In Vivo Receptor Imaging Literature

    PubMed Central

    Stone, James M.; Davis, John M.; Leucht, Stefan; Pilowsky, Lyn S.

    2009-01-01

    Subject numbers in neuroreceptor imaging studies of antipsychotic treatment in schizophrenia are generally insufficient to directly test the relationship of regional D2/D3 and 5HT2A receptor binding to clinical efficacy. We selected positron emission tomography (PET) and single photon emission computed tomography (SPECT) studies of antipsychotic dose vs occupancy at both temporal cortex and striatal D2/D3 receptors. We selected corresponding SPECT and PET studies of 5HT2A receptor occupancy. We also selected randomized double-blind clinical trials of antipsychotics, where patients were treated with randomly assigned fixed doses. For each antipsychotic drug, we compared the optimum effective antipsychotic dose with the dose inducing maximal occupancy of D2/D3 receptors in striatum and in temporal cortex as well as at 5HT2A receptors. Both first- and second-generation antipsychotic (FGA, SGA) drugs produced high temporal cortex D2/D3 occupancy. Only FGA produced high striatal D2/D3 receptor occupancy. The clinically effective dose showed correlation with doses inducing maximal dopamine D2/D3 receptor occupancy both in striatum and in temporal cortex, the strongest correlation being with temporal cortex binding. Extrapyramidal side effects (EPSE) were primarily related to striatal D2/D3 receptor occupancy. There was no correlation between 5HT2A occupancy and clinically effective dose. We conclude that cortical dopamine D2/D3 receptor occupancy is involved in antipsychotic efficacy, with striatal D2/D3 occupancy having a likely therapeutic role while also inducing EPSE. We found no evidence for 5HT2A blockade involvement in antipsychotic action, although we cannot exclude this possibility. PMID:18303092

  14. A comparative study of DIGNET, average, complete, single hierarchical and k-means clustering algorithms in 2D face image recognition

    NASA Astrophysics Data System (ADS)

    Thanos, Konstantinos-Georgios; Thomopoulos, Stelios C. A.

    2014-06-01

    The study in this paper belongs to a more general research of discovering facial sub-clusters in different ethnicity face databases. These new sub-clusters along with other metadata (such as race, sex, etc.) lead to a vector for each face in the database where each vector component represents the likelihood of participation of a given face to each cluster. This vector is then used as a feature vector in a human identification and tracking system based on face and other biometrics. The first stage in this system involves a clustering method which evaluates and compares the clustering results of five different clustering algorithms (average, complete, single hierarchical algorithm, k-means and DIGNET), and selects the best strategy for each data collection. In this paper we present the comparative performance of clustering results of DIGNET and four clustering algorithms (average, complete, single hierarchical and k-means) on fabricated 2D and 3D samples, and on actual face images from various databases, using four different standard metrics. These metrics are the silhouette figure, the mean silhouette coefficient, the Hubert test Γ coefficient, and the classification accuracy for each clustering result. The results showed that, in general, DIGNET gives more trustworthy results than the other algorithms when the metrics values are above a specific acceptance threshold. However when the evaluation results metrics have values lower than the acceptance threshold but not too low (too low corresponds to ambiguous results or false results), then it is necessary for the clustering results to be verified by the other algorithms.

  15. Imaging Transverse Isotropic Properties of Muscle by Monitoring Acoustic Radiation Force Induced Shear Waves using a 2D Matrix Ultrasound Array

    PubMed Central

    Wang, Michael; Byram, Brett; Palmeri, Mark; Rouze, Ned; Nightingale, Kathryn

    2013-01-01

    A 2D matrix ultrasound array is used to monitor acoustic radiation force impulse (ARFI) induced shear wave propagation in 3D in excised canine muscle. From a single acquisition, both the shear wave phase and group velocity can be calculated to estimate the shear wave speed (SWS) along and across the fibers, as well as the fiber orientation in 3D. The true fiber orientation found using the 3D Radon Transform on B-mode volumes of the muscle was used to verify the fiber direction estimated from shear wave data. For the simplified imaging case when the ARFI push can be oriented perpendicular to the fibers, the error in estimating the fiber orientation using phase and group velocity measurements was 3.5 ±2.6° and 3.4 ±1.4° (mean ± standard deviation), respectively, over six acquisitions in different muscle samples. For the more general case when the push is oblique to the fibers, the angle between the push and the fibers is found using the dominant orientation of the shear wave displacement magnitude. In 30 acquisitions on six different muscle samples with oblique push angles up to 40°, the error in the estimated fiber orientation using phase and group velocity measurements was 5.4±2.9° and 5.3±3.2°, respectively, after estimating and accounting for the additional unknown push angle. Either the phase or group velocity measurements can be used to estimate fiber orientation and SWS along and across the fibers. Although it is possible to perform these measurements when the push is not perpendicular to the fibers, highly oblique push angles induce lower shear wave amplitudes which can cause inaccurate SWS measurements. PMID:23686942

  16. PIV, 2D-LIF and 1D-Raman measurements of flow field, composition and temperature in premixed gas turbine flames

    SciTech Connect

    Stopper, U.; Aigner, M.; Ax, H.; Meier, W.; Sadanandan, R.; Stoehr, M.; Bonaldo, A.

    2010-04-15

    Several laser diagnostic measurement techniques have been applied to study the lean premixed natural gas/air flames of an industrial swirl burner. This was made possible by equipping the burner with an optical combustion chamber that was installed in the high-pressure test rig facility at the DLR Institute of Combustion Technology in Stuttgart. The burner was operated with preheated air at various operating conditions with pressures up to p = 6 bar and a maximum thermal power of P = 1 MW. The instantaneous planar flow field inside the combustor was studied with particle image velocimetry (PIV). Planar laser induced fluorescence (PLIF) of OH radicals on a single-shot basis was used to determine the shape and the location of the flame front as well as the spatial distribution of reaction products. 1D laser Raman spectroscopy was successfully applied for the measurement of the temperature and the concentration of major species under realistic gas turbine conditions. Results of the flow field analysis show the shape and the size of the main flow regimes: the inflow region, the inner and the outer recirculation zone. The highly turbulent flow field of the inner shear layer is found to be dominated by small and medium sized vortices. High RMS fluctuations of the flow velocity in the exhaust gas indicate the existence of a rotating exhaust gas swirl. From the PLIF images it is seen that the primary reactions happened in the shear layers between inflow and the recirculation zones and that the appearance of the reaction zones changed with flame parameters. The results of the multiscalar Raman measurements show a strong variation of the local mixture fraction allowing conclusions to be drawn about the premix quality. Furthermore, mixing effects of unburnt fuel and air with fully reacted combustion products are studied giving insights into the processes of the turbulence-chemistry interaction. (author)

  17. Aniso2D

    Energy Science and Technology Software Center (ESTSC)

    2005-07-01

    Aniso2d is a two-dimensional seismic forward modeling code. The earth is parameterized by an X-Z plane in which the seismic properties Can have monoclinic with x-z plane symmetry. The program uses a user define time-domain wavelet to produce synthetic seismograms anrwhere within the two-dimensional media.

  18. The identified origin of a linear slope near Chi-Chi earthquake rupture combining 2D, 3D resistivity image profiling and geological data

    NASA Astrophysics Data System (ADS)

    Lee, Cheng-Chao; Tsai, Louis Loung-Yie; Yang, Chieh-Hou; Wen, Kuo-Liang; Wang, Zi-Bin; Hsieh, Zhi-Hsian; Liu, Hsing-Chang

    2009-10-01

    A slope on the west border of the foothill near 921 surface rupture (caused by the 1999 Chi-Chi earthquake) in central Taiwan shows distinctive topographic expression that was prone to be considered as a fault scarp formed by a preexisting active fault. The 2D and 3D resistivity images clearly delineate rock surfaces which show steep, deep, gentle, and subvertical displacement beneath the slope, the toe of slope, the non-lateritic terrace, and 921 surface rupture, respectively, which can be attributed to the significant contrast of resistivity between gravel and rock. The horizontal sand bed and clast-supported gravel were deposited in a fluvial environment, whereas wedge-shaped gravel and colluvium were scarp-induced colluvial deposits in the trench profile. The layers shown in the depth of excavation, except for rock, has no offset or disturbance by fault ever since at least 2,480 ± 50 year B.P., based on carbon 14 dating of charcoal sample at the bottom of trench profile. According to information from two boreholes close to the slope, an over 20-m-thick marker bed with transported shell fragments, was found for correlation. This correlation further implies the slope was not formed by fault. On the other hand, two boreholes which are far from the slope and located on the flat non-lateritic terrace frequently show fractured and sheared features. By comparison, the locations around these two boreholes indicate a reverse fault or faults that occurred before the deposition of gravel. Later on, the paleostream was developed along the foot of fault scarp that was subjected to erosion and led to subsequent retrogression or retreat of the slope. Consequently, the incision of paleostream is believed to be responsible for the high relief of rock surface around the slope. Furthermore, from resistivity and borehole data, the rock surface underlying terrace is gentle where no faults occur after the deposition of gravel. The result of RIP crossing the 921 surface rupture displays about 10 m difference in elevation of rock surface on both sides, which is greater than that of 3-4 m caused by Chi-Chi earthquake. This indicates that the 921 surface rupture is a preexisting thrust fault that resulted from several thrusting events since terrace gravel was deposited. So it is not necessary to establish an extra restricted zone for construction in study area, except close to the 921 surface rupture.

  19. Mesh2d

    SciTech Connect

    Greg Flach, Frank Smith

    2011-12-31

    Mesh2d is a Fortran90 program designed to generate two-dimensional structured grids of the form [x(i),y(i,j)] where [x,y] are grid coordinates identified by indices (i,j). The x(i) coordinates alone can be used to specify a one-dimensional grid. Because the x-coordinates vary only with the i index, a two-dimensional grid is composed in part of straight vertical lines. However, the nominally horizontal y(i,j0) coordinates along index i are permitted to undulate or otherwise vary. Mesh2d also assigns an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations.

  20. Mesh2d

    Energy Science and Technology Software Center (ESTSC)

    2011-12-31

    Mesh2d is a Fortran90 program designed to generate two-dimensional structured grids of the form [x(i),y(i,j)] where [x,y] are grid coordinates identified by indices (i,j). The x(i) coordinates alone can be used to specify a one-dimensional grid. Because the x-coordinates vary only with the i index, a two-dimensional grid is composed in part of straight vertical lines. However, the nominally horizontal y(i,j0) coordinates along index i are permitted to undulate or otherwise vary. Mesh2d also assignsmore » an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations.« less

  1. DUst Sounder and Temperature Imager Experiment (DUSTIE)

    NASA Astrophysics Data System (ADS)

    McHugh, M. J.; Fish, C. S.; Taylor, M. J.; Gordley, L. L.; Hervig, M. E.; Summers, M. E.; Siskind, D. E.

    2009-12-01

    The Dust Sounder and Temperature Imager Experiment (DUSTIE) is a proposed CubeSat mission to determine the global distribution of cosmic smoke in the atmosphere. The Earth is under continual bombardment by comets and meteoroids. Over the last 5 billion years they have brought water and the basics of life to our planet. Today they are vaporized during atmospheric entry and deposited as microscopic smoke particles in the upper atmosphere. These cosmic particles are known to be important in a host of atmospheric processes, including nucleation of ice particles, ion chemistry in the thermosphere and heterogeneous chemistry in the mesosphere. Despite this, our current understanding is based on scant observations and theory. The successful deployment of DUSTIE will offer a major advance in this important emerging area of research. DUSTIE will use a digital camera to image the Sun at 0.420 µm during spacecraft sunrise and sunset. This will provide measurements to characterize the smoke distribution over the altitude range of ~40 to 90 km. A high-inclination orbit will provide near-global coverage monthly. Simultaneous refraction measurements will yield atmospheric density profiles up to 75 km. Measured smoke extinctions will be used to derive smoke particle volume and surface area densities. DUSTIE will utilize a 3U form factor CubeSat and rely heavily upon commercial-off-the-shelf (COTS) components and proven technologies.

  2. Vertical 2D Heterostructures

    NASA Astrophysics Data System (ADS)

    Lotsch, Bettina V.

    2015-07-01

    Graphene's legacy has become an integral part of today's condensed matter science and has equipped a whole generation of scientists with an armory of concepts and techniques that open up new perspectives for the postgraphene area. In particular, the judicious combination of 2D building blocks into vertical heterostructures has recently been identified as a promising route to rationally engineer complex multilayer systems and artificial solids with intriguing properties. The present review highlights recent developments in the rapidly emerging field of 2D nanoarchitectonics from a materials chemistry perspective, with a focus on the types of heterostructures available, their assembly strategies, and their emerging properties. This overview is intended to bridge the gap between two major—yet largely disjunct—developments in 2D heterostructures, which are firmly rooted in solid-state chemistry or physics. Although the underlying types of heterostructures differ with respect to their dimensions, layer alignment, and interfacial quality, there is common ground, and future synergies between the various assembly strategies are to be expected.

  3. GelScape: a web-based server for interactively annotating, manipulating, comparing and archiving 1D and 2D gel images.

    PubMed

    Young, Nelson; Chang, Zhan; Wishart, David S

    2004-04-12

    GelScape is a web-based tool that permits facile, interactive annotation, comparison, manipulation and storage of protein gel images. It uses Java applet-servlet technology to allow rapid, remote image handling and image processing in a platform-independent manner. It supports many of the features found in commercial, stand-alone gel analysis software including spot annotation, spot integration, gel warping, image resizing, HTML image mapping, image overlaying as well as the storage of gel image and gel annotation data in compliance with Federated Gel Database requirements. PMID:14764570

  4. Temperature sensitivity of Cu K(alpha) imaging efficiency using a spherical Bragg reflecting crystal

    SciTech Connect

    Akli, K U; Key, M H; Chung, H K; Hansen, S B; Freeman, R R; Chen, M H; Gregori, G; Hatchett, S; Hey, D; Izumi, N; King, J A; Kuba, J; Norreys, P; Mackinnon, A J; Murphy, C D; Snavely, R; Stepehens, R; Stoeckel, C; Theobald, W; Zhang, B

    2006-08-07

    The Vulcan laser facility at the Rutherford Appleton Laboratory was used to study the interaction of a 75 J 10 ps, high intensity laser beam with low-mass solid, Cu targets. Two instruments were fielded as diagnostics of the Cu K-shell emission from the targets: A single photon counting CCD spectrometer provided the absolute K{sub {alpha}} yield and a spherically bent Bragg crystal recorded 2D monochromatic images with a spatial resolution of 10 {micro}m. Due to the shifting and broadening of the K{sub {alpha}} spectral lines with increasing temperature, there is a temperature dependence of the crystal collection efficiency. This provides a temperature diagnostic when cross calibrated against a single hit CCD spectrometer, and it affects measurements of the spatial pattern of electron transport. The experimental data showing changing collection efficiency are presented. The results are discussed in light of modeling of the temperature-dependent spectrum of Cu K-shell emission.

  5. A Novel 2D Image Compression Algorithm Based on Two Levels DWT and DCT Transforms with Enhanced Minimize-Matrix-Size Algorithm for High Resolution Structured Light 3D Surface Reconstruction

    NASA Astrophysics Data System (ADS)

    Siddeq, M. M.; Rodrigues, M. A.

    2015-09-01

    Image compression techniques are widely used on 2D image 2D video 3D images and 3D video. There are many types of compression techniques and among the most popular are JPEG and JPEG2000. In this research, we introduce a new compression method based on applying a two level discrete cosine transform (DCT) and a two level discrete wavelet transform (DWT) in connection with novel compression steps for high-resolution images. The proposed image compression algorithm consists of four steps. (1) Transform an image by a two level DWT followed by a DCT to produce two matrices: DC- and AC-Matrix, or low and high frequency matrix, respectively, (2) apply a second level DCT on the DC-Matrix to generate two arrays, namely nonzero-array and zero-array, (3) apply the Minimize-Matrix-Size algorithm to the AC-Matrix and to the other high-frequencies generated by the second level DWT, (4) apply arithmetic coding to the output of previous steps. A novel decompression algorithm, Fast-Match-Search algorithm (FMS), is used to reconstruct all high-frequency matrices. The FMS-algorithm computes all compressed data probabilities by using a table of data, and then using a binary search algorithm for finding decompressed data inside the table. Thereafter, all decoded DC-values with the decoded AC-coefficients are combined in one matrix followed by inverse two levels DCT with two levels DWT. The technique is tested by compression and reconstruction of 3D surface patches. Additionally, this technique is compared with JPEG and JPEG2000 algorithm through 2D and 3D root-mean-square-error following reconstruction. The results demonstrate that the proposed compression method has better visual properties than JPEG and JPEG2000 and is able to more accurately reconstruct surface patches in 3D.

  6. Temperature-dependent kinetic measurements and quasi-classical trajectory studies for the OH+ + H2/D2 → H2O+/HDO+ + H/D reactions

    NASA Astrophysics Data System (ADS)

    Martinez, Oscar; Ard, Shaun G.; Li, Anyang; Shuman, Nicholas S.; Guo, Hua; Viggiano, Albert A.

    2015-09-01

    We have measured the temperature-dependent kinetics for the reactions of OH+ with H2 and D2 using a selected ion flow tube apparatus. Reaction occurs via atom abstraction to result in H2O+/HDO+ + H/D. Room temperature rate coefficients are in agreement with prior measurements and resulting temperature dependences are T0.11 for the hydrogen and T0.25 for the deuterated reactions. This work is prompted in part by recent theoretical work that mapped a full-dimensional global potential energy surface of H3O+ for the OH+ + H2 → H + H2O+ reaction [A. Li and H. Guo, J. Phys. Chem. A 118, 11168 (2014)], and reported results of quasi-classical trajectory calculations, which are extended to a wider temperature range and initial rotational state specification here. Our experimental results are in excellent agreement with these calculations which accurately predict the isotope effect in addition to an enhancement of the reaction rate constant due to the molecular rotation of OH+. The title reaction is of high importance to astrophysical models, and the temperature dependence of the rate coefficients determined here should now allow for better understanding of this reaction at temperatures more relevant to the interstellar medium.

  7. Temperature-dependent kinetic measurements and quasi-classical trajectory studies for the OH(+) + H2/D2 → H2O(+)/HDO(+) + H/D reactions.

    PubMed

    Martinez, Oscar; Ard, Shaun G; Li, Anyang; Shuman, Nicholas S; Guo, Hua; Viggiano, Albert A

    2015-09-21

    We have measured the temperature-dependent kinetics for the reactions of OH(+) with H2 and D2 using a selected ion flow tube apparatus. Reaction occurs via atom abstraction to result in H2O(+)/HDO(+) + H/D. Room temperature rate coefficients are in agreement with prior measurements and resulting temperature dependences are T(0.11) for the hydrogen and T(0.25) for the deuterated reactions. This work is prompted in part by recent theoretical work that mapped a full-dimensional global potential energy surface of H3O(+) for the OH(+) + H2 → H + H2O(+) reaction [A. Li and H. Guo, J. Phys. Chem. A 118, 11168 (2014)], and reported results of quasi-classical trajectory calculations, which are extended to a wider temperature range and initial rotational state specification here. Our experimental results are in excellent agreement with these calculations which accurately predict the isotope effect in addition to an enhancement of the reaction rate constant due to the molecular rotation of OH(+). The title reaction is of high importance to astrophysical models, and the temperature dependence of the rate coefficients determined here should now allow for better understanding of this reaction at temperatures more relevant to the interstellar medium. PMID:26395708

  8. Imaging system based on a tandem acousto-optical tunable filter for in situ measurements of the high temperature distribution.

    PubMed

    Machikhin, Alexander S; Zinin, Pavel V; Shurygin, Alexander V; Khokhlov, Demid D

    2016-03-01

    We present, to the best of our knowledge, the first experimental demonstration of a new imaging system for in situ measurement of the two-dimensional (2D) distribution of the surface temperature of microscopic specimens. The main component of the system is an imaging tandem acousto-optical tunable filter (TAOTF) synchronized with a video camera. A set of TAOTF spectroscopic images (up to a few hundreds) is taken by the TAOTF imaging system to fit the measured spectral curves in each pixel to the Planck radiation function and determine the temperature and emissivity of the sample using the gray body approximation. It is experimentally shown that this technique provides aberration-free spectral imaging suitable for precise multispectral imaging radiometry (MIR). PMID:26974075

  9. Recognition of a 3D snake model and its 2D photographic image by captive black tufted-ear marmosets (Callithrix penicillata).

    PubMed

    Emile, Nally; Barros, Marilia

    2009-09-01

    Two-dimensional (2D) displays of real three-dimensional (3D) objects are frequently used experimental tools in animal studies. Whether marmoset monkeys, with their highly diverse and complex anti-predation strategies, readily recognized 2D representations of potential threats has yet to be determined, as seen in other primates. Thus, the behavioral responses of adult captive black tufted-ear marmosets (Callithrix penicillata) toward an unfamiliar motionless snake-model and its photograph were assessed. Pictorially naïve subjects were randomly divided into two groups (n = 12/each) and submitted to two trials. Group 1 was initially exposed to the 3D object and after 1 week to its photograph. Group 2 was first presented the picture and only tested with the real object 1 week later. All 15-min trials were divided into three consecutive 5-min intervals: pre-exposure, exposure and post-exposure. In the presence of the 3D snake object, regardless of its presentation order, the frequency of direct gazes, head-cocks, tsik-tsik alarm/mobbing calls and genital displays increased significantly. The photograph induced a similar response, although only when the object had been previously presented, as significantly higher levels of these behaviors were seen in Group 1 than Group 2. Proximity to the stimulus, aerial scan, terrestrial glance, displacement activities and locomotion were not consistently influenced by the stimuli's presence and/or order of presentation. Therefore, marmosets recognized and responded appropriately to biologically and emotionally relevant 3D and 2D stimuli. Since the aversive/fearful reactions toward the photograph were only seen after the snake object had been presented, the former seems to be essentially a learned response. PMID:19449190

  10. The relationship between substructure in 2D X-ray surface brightness images and weak-lensing mass maps of galaxy clusters: a simulation study

    NASA Astrophysics Data System (ADS)

    Powell, Leila C.; Kay, Scott T.; Babul, Arif

    2009-12-01

    Recent X-ray and weak-lensing observations of galaxy clusters have revealed that the hot gas does not always directly trace the dark matter within these systems. Such configurations are extremely interesting. They offer a new vista on to the complex interplay between gravity and baryonic physics, and may even be used as indicators of the clusters' dynamical state. In this paper, we undertake a study to determine what insight can be reliably gleaned from the comparison of the X-ray and the weak-lensing mass maps of galaxy clusters. We do this by investigating the two-dimensional (2D) substructure within three high-resolution cosmological simulations of galaxy clusters. Our main results focus on non-radiative gas dynamics, but we also consider the effects of radiative cooling at high redshift. For our analysis, we use a novel approach, based on unsharp-masking, to identify substructures in 2D surface mass density and X-ray surface brightness maps. At full resolution (~15h-1 kpc), this technique is capable of identifying almost all self-bound dark matter subhaloes with M > 1012h-1Msolar. We also report a correlation between the mass of a subhalo and the area of its corresponding 2D detection; such a correlation, once calibrated, could provide a useful estimator for substructure mass. Comparing our 2D mass and X-ray substructures, we find a surprising number of cases where the matching fails: around one-third of galaxy-sized substructures have no X-ray counterpart. Some interesting cases are also found at larger masses, in particular the cores of merging clusters where the situation can be complex. Finally, we degrade our mass maps to what is currently achievable with weak-lensing observations (~100h-1kpc at z = 0.2). While the completeness mass limit increases by around an order of magnitude, a mass-area correlation remains. Our paper clearly demonstrates that the next generation of lensing surveys should start to reveal a wealth of information on cluster substructure.

  11. Temperature dependent structural variation from 2D supramolecular network to 3D interpenetrated metal–organic framework: In situ cleavage of S–S and C–S bonds

    SciTech Connect

    Ugale, Bharat; Singh, Divyendu; Nagaraja, C.M.

    2015-03-15

    Two new Zn(II)–organic compounds, [Zn(muco)(dbds){sub 2}(H{sub 2}O){sub 2}] (1) and [Zn(muco)(dbs)] (2) (where, muco=trans, trans-muconate dianion, dbds=4,4′-dipyridyldisulfide and dbs=4,4′-dipyridylsulfide) have been synthesized from same precursors but at two different temperatures. Both the compounds have been characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, IR spectroscopy, thermal analysis and photoluminescence studies. Compound 1 prepared at room temperature possesses a molecular structure extended to 2D supramolecular network through (H–O…H) hydrogen-bonding interactions. Compound 2, obtained at high temperature (100 °C) shows a 3-fold interpenetrating 3D framework constituted by an in situ generated dbs linker by the cleavage of S–S and C–S bonds of dbds linker. Thus, the influence of reaction temperature on the formation of two structural phases has been demonstrated. Both 1 and 2 exhibit ligand based luminescence emission owing to n→π⁎ and π→π⁎ transitions and also high thermal stabilities. - Graphical abstract: The influence of temperature on the formation of two structural phases, a 2D supramolecular network and a 3D 3-fold interpenetrating framework has been demonstrated and their luminescence emission is measured. - Highlights: • Two new Zn(II)–organic compounds were synthesized by tuning reaction temperatures. • Temperature induced in situ generation of dbs linker has been observed. • The compounds exhibit high thermal stability and luminescence emission properties. • The effect of temperature on structure, dimension and topology has been presented.

  12. Post calibration of the two-dimensional electron cyclotron emission imaging instrument with electron temperature characteristics of the magnetohydrodynamic instabilities.

    PubMed

    Choi, M J; Park, H K; Yun, G S; Nam, Y B; Choe, G H; Lee, W; Jardin, S

    2016-01-01

    The electron cyclotron emission imaging (ECEI) instrument is widely used to study the local electron temperature (Te) fluctuations by measuring the ECE intensity IECE ∝ Te in tokamak plasmas. The ECEI measurement is often processed in a normalized fluctuation quantity against the time averaged value due to complication in absolute calibration. In this paper, the ECEI channels are relatively calibrated using the flat Te assumption of the sawtooth crash or the tearing mode island and a proper extrapolation. The 2-D relatively calibrated electron temperature (Te,rel) images are reconstructed and the displacement amplitude of the magnetohydrodynamic modes can be measured for the accurate quantitative growth analysis. PMID:26827320

  13. Revisiting 2D Lattice Based Spin Flip-Flop Ising Model: Magnetic Properties of a Thin Film and Its Temperature Dependence

    ERIC Educational Resources Information Center

    Singh, Satya Pal

    2014-01-01

    This paper presents a brief review of Ising's work done in 1925 for one dimensional spin chain with periodic boundary condition. Ising observed that no phase transition occurred at finite temperature in one dimension. He erroneously generalized his views in higher dimensions but that was not true. In 1941 Kramer and Wannier obtained…

  14. Comparison of 2D and 3D Imaging and Treatment Planning for Postoperative Vaginal Apex High-Dose Rate Brachytherapy for Endometrial Cancer

    SciTech Connect

    Russo, James K.; Armeson, Kent E.; Richardson, Susan

    2012-05-01

    Purpose: To evaluate bladder and rectal doses using two-dimensional (2D) and 3D treatment planning for vaginal cuff high-dose rate (HDR) in endometrial cancer. Methods and Materials: Ninety-one consecutive patients treated between 2000 and 2007 were evaluated. Seventy-one and 20 patients underwent 2D and 3D planning, respectively. Each patient received six fractions prescribed at 0.5 cm to the superior 3 cm of the vagina. International Commission on Radiation Units and Measurements (ICRU) doses were calculated for 2D patients. Maximum and 2-cc doses were calculated for 3D patients. Organ doses were normalized to prescription dose. Results: Bladder maximum doses were 178% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were no different than ICRU doses (p = 0.22). Two-cubic centimeter doses were 59% of maximum doses (p < 0.0001). Rectal maximum doses were 137% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 87% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 64% of maximum doses (p < 0.0001). Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final bladder dose to within 10% for 44%, 59%, 83%, 82%, and 89% of patients by using the ICRU dose, and for 45%, 55%, 80%, 85%, and 85% of patients by using the maximum dose, and for 37%, 68%, 79%, 79%, and 84% of patients by using the 2-cc dose. Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final rectal dose to within 10% for 100%, 100%, 100%, 100%, and 100% of patients by using the ICRU dose, and for 60%, 65%, 70%, 75%, and 75% of patients by using the maximum dose, and for 68%, 95%, 84%, 84%, and 84% of patients by using the 2-cc dose. Conclusions: Doses to organs at risk vary depending on the calculation method. In some cases, final dose accuracy appears to plateau after the third fraction, indicating that simulation and planning may not be necessary in all fractions. A clinically relevant level of accuracy should be determined and further research conducted to address this issue.

  15. Three-dimensional mapping of soil chemical characteristics at micrometric scale: Statistical prediction by combining 2D SEM-EDX data and 3D X-ray computed micro-tomographic images

    NASA Astrophysics Data System (ADS)

    Hapca, Simona

    2015-04-01

    Many soil properties and functions emerge from interactions of physical, chemical and biological processes at microscopic scales, which can be understood only by integrating techniques that traditionally are developed within separate disciplines. While recent advances in imaging techniques, such as X-ray computed tomography (X-ray CT), offer the possibility to reconstruct the 3D physical structure at fine resolutions, for the distribution of chemicals in soil, existing methods, based on scanning electron microscope (SEM) and energy dispersive X-ray detection (EDX), allow for characterization of the chemical composition only on 2D surfaces. At present, direct 3D measurement techniques are still lacking, sequential sectioning of soils, followed by 2D mapping of chemical elements and interpolation to 3D, being an alternative which is explored in this study. Specifically, we develop an integrated experimental and theoretical framework which combines 3D X-ray CT imaging technique with 2D SEM-EDX and use spatial statistics methods to map the chemical composition of soil in 3D. The procedure involves three stages 1) scanning a resin impregnated soil cube by X-ray CT, followed by precision cutting to produce parallel thin slices, the surfaces of which are scanned by SEM-EDX, 2) alignment of the 2D chemical maps within the internal 3D structure of the soil cube, and 3) development, of spatial statistics methods to predict the chemical composition of 3D soil based on the observed 2D chemical and 3D physical data. Specifically, three statistical models consisting of a regression tree, a regression tree kriging and cokriging model were used to predict the 3D spatial distribution of carbon, silicon, iron and oxygen in soil, these chemical elements showing a good spatial agreement between the X-ray grayscale intensities and the corresponding 2D SEM-EDX data. Due to the spatial correlation between the physical and chemical data, the regression-tree model showed a great potential in predicting chemical composition in particular for iron, which is generally sparsely distributed in soil. For carbon, silicon and oxygen, which are more densely distributed, the additional kriging of the regression tree residuals improved significantly the prediction, whereas prediction based on co-kriging was less consistent across replicates, underperforming regression-tree kriging. The present study shows a great potential in integrating geo-statistical methods with imaging techniques to unveil the 3D chemical structure of soil at very fine scales, the framework being suitable to be further applied to other types of imaging data such as images of biological thin sections for characterization of microbial distribution. Key words: X-ray CT, SEM-EDX, segmentation techniques, spatial correlation, 3D soil images, 2D chemical maps.

  16. Some advances/results in monitoring road cracks from 2D pavement images within the scope of the collaborative FP7 TRIMM project

    NASA Astrophysics Data System (ADS)

    Baltazart, Vincent; Moliard, Jean-Marc; Amhaz, Rabih; Wright, Dean; Jethwa, Manish

    2015-04-01

    Monitoring road surface conditions is an important issue in many countries. Several projects have looked into this issue in recent years, including TRIMM 2011-2014. The objective of such projects has been to detect surface distresses, like cracking, raveling and water ponding, in order to plan effective road maintenance and to afford a better sustainability of the pavement. The monitoring of cracking conventionally focuses on open cracks on the surface of the pavement, as opposed to reflexive cracks embedded in the pavement materials. For monitoring surface condition, in situ human visual inspection has been gradually replaced by automatic image data collection at traffic speed. Off-line image processing techniques have been developed for monitoring surface condition in support of human visual control. Full automation of crack monitoring has been approached with caution, and depends on a proper manual assessment of the performance. This work firstly presents some aspects of the current state of monitoring that have been reported so far in the literature and in previous projects: imaging technology and image processing techniques. Then, the work presents the two image processing techniques that have been developed within the scope of the TRIMM project to automatically detect pavement cracking from images. The first technique is a heuristic approach (HA) based on the search for gradient within the image. It was originally developed to process pavement images from the French imaging device, Aigle-RN. The second technique, the Minimal Path Selection (MPS) method, has been developed within an ongoing PhD work at IFSTTAR. The proposed new technique provides a fine and accurate segmentation of the crack pattern along with the estimation of the crack width. HA has been assessed against the field data collection provided by Yotta and TRL with the imaging device Tempest 2. The performance assessment has been threefold: first it was performed against the reference data set including 130 km of pavement images over UK roads, second over a few selected short sections of contiguous pavement images, and finally over a few sample images as a case study. The performance of MPS has been assessed against an older image data base. Pixel-based PGT was available to provide the most sensitive performance assessment. MPS has shown its ability to provide a very accurate cracking pattern without reducing the image resolution on the segmented images. Thus, it allows measurement of the crack width; it is found to behave more robustly against the image texture and better matched for dealing with low contrast pavement images. The benchmarking of seven automatic segmentation techniques has been provided at both the pixel and the grid levels. The performance assessment includes three minimal path selection algorithms, namely MPS, Free Form Anisotropy (FFA), one geodesic contour with automatic selection of points of interests (GC-POI), HA, and two Markov-based methods. Among others, MPS approach reached the best performance at the pixel level while it is matched to the FFA approach at the grid level. Finally, the project has emphasized the need for a reliable ground truth data collection. Owing to its accuracy, MPS may serve as a reference benchmark for other methods to provide the automatic segmentation of pavement images at the pixel level and beyond. As a counterpart, MPS requires a reduction in the computing time. Keywords: cracking, automatic segmentation, image processing, pavement, surface distress, monitoring, DICE, performance

  17. A molecular dynamics study of twin width, grain size and temperature effects on the toughness of 2D-columnar nanotwinned copper

    NASA Astrophysics Data System (ADS)

    Shabib, I.; Miller, R. E.

    2009-07-01

    The introduction of twin boundaries (TBs) within nanocrystalline grains has given scientists an opportunity to enhance mechanical properties that are usually mutually exclusive: strength and ductility. This research is focused on developing a complete understanding of the influences of twin width, grain size and temperature on the deformation characteristics and properties of nanotwinned Cu by large-scale molecular dynamics simulations. Simulation results have shown that a material's toughness can be enhanced by introducing nanotwins, and the enhancement is more pronounced for the higher twin density structures and at lower temperatures. Nanotwinned grains are found to be highly anisotropic in their plastic response; ductile along TBs but strong across them. A random polycrystalline sample gains toughness through the combined response of variously oriented grains. At extremely low temperature, toughness values are elevated further due to depressed dislocation activities inside the grains. The study has also revealed that, unlike twin width refinement, grain size refinement may not always yield superior properties, and may deteriorate material toughness.

  18. Quantitative Temperature Imaging in Gas-Phase Turbulent Thermal Convection by Laser-Induced Fluorescence of Acetone

    SciTech Connect

    KEARNEY,SEAN P.; REYES,FELIPE V.

    2000-12-13

    In this paper, an acetone planar laser-induced fluorescence (PLIF) technique for nonintrusive, temperature imaging is demonstrated in gas-phase (Pr = 0.72) turbulent Rayleigh-Benard convection at Rayleigh number, Ra = 1.3 x 10{sup 5}. The PLIF technique provides quantitative, spatially correlated temperature data without the flow intrusion or time lag associated with physical probes and without the significant path averaging that plagues most optical heat-transfer diagnostic tools, such as the Mach-Zehnder interferometer, thus making PLIF an attractive choice for quantitative thermal imaging in easily perturbed, complex three-dimensional flow fields. The instantaneous (20-ns integration time) thermal images presented have a spatial resolution of 176 x 176 x 500 {micro}m and a single-pulse temperature measurement precision of {+-}5.5 K, or 5.4 % of the total temperature difference. These images represent a 2-D slice through a complex, 3-D flow allowing for the thermal structure of the turbulence to be quantified. Statistics such as the horizontally averaged temperature profile, rms temperature fluctuation, two-point spatial correlations, and conditionally averaged plume structures are computed from an ensemble of 100 temperature images. The profiles of the mean temperature and rms temperature fluctuation are in good agreement with previously published data, and the results obtained from the two-point spatial correlations and conditionally averaged temperature fields show the importance of large-scale coherent structures in this turbulent flow.

  19. Definitions for a common standard for 2D speckle tracking echocardiography: consensus document of the EACVI/ASE/Industry Task Force to standardize deformation imaging.

    PubMed

    Voigt, Jens-Uwe; Pedrizzetti, Gianni; Lysyansky, Peter; Marwick, Tom H; Houle, Hélène; Baumann, Rolf; Pedri, Stefano; Ito, Yasuhiro; Abe, Yasuhiko; Metz, Stephen; Song, Joo Hyun; Hamilton, Jamie; Sengupta, Partho P; Kolias, Theodore J; d'Hooge, Jan; Aurigemma, Gerard P; Thomas, James D; Badano, Luigi Paolo

    2015-02-01

    Recognizing the critical need for standardization in strain imaging, in 2010, the European Association of Echocardiography (now the European Association of Cardiovascular Imaging, EACVI) and the American Society of Echocardiography (ASE) invited technical representatives from all interested vendors to participate in a concerted effort to reduce intervendor variability of strain measurement. As an initial product of the work of the EACVI/ASE/Industry initiative to standardize deformation imaging, we prepared this technical document which is intended to provide definitions, names, abbreviations, formulas, and procedures for calculation of physical quantities derived from speckle tracking echocardiography and thus create a common standard. PMID:25623220

  20. Definitions for a common standard for 2D speckle tracking echocardiography: consensus document of the EACVI/ASE/Industry Task Force to standardize deformation imaging.

    PubMed

    Voigt, Jens-Uwe; Pedrizzetti, Gianni; Lysyansky, Peter; Marwick, Tom H; Houle, Helen; Baumann, Rolf; Pedri, Stefano; Ito, Yasuhiro; Abe, Yasuhiko; Metz, Stephen; Song, Joo Hyun; Hamilton, Jamie; Sengupta, Partho P; Kolias, Theodore J; d'Hooge, Jan; Aurigemma, Gerard P; Thomas, James D; Badano, Luigi Paolo

    2015-01-01

    Recognizing the critical need for standardization in strain imaging, in 2010, the European Association of Echocardiography (now the European Association of Cardiovascular Imaging, EACVI) and the American Society of Echocardiography (ASE) invited technical representatives from all interested vendors to participate in a concerted effort to reduce intervendor variability of strain measurement. As an initial product of the work of the EACVI/ASE/Industry initiative to standardize deformation imaging, we prepared this technical document which is intended to provide definitions, names, abbreviations, formulas, and procedures for calculation of physical quantities derived from speckle tracking echocardiography and thus create a common standard. PMID:25525063

  1. Temperature-driven disorder-order transitions in 2D copper-intercalated MoO3 revealed using dynamic transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Reed, Bryan W.; Chung, Frank R.; Wang, Mengjing; LaGrange, Thomas; Koski, Kristie J.

    2014-12-01

    We demonstrate two different classes of disorder-order phase transitions in two-dimensional layered nanomaterial MoO3 intercalated with ˜9-15 atomic percent zero-valent copper using conventional in situ electron diffraction and dynamic transmission electron microscopy. Heating to ˜325 °C on a time scale of minutes produces a superlattice consistent with the formation of a charge density wave stabilized by nanometer-scale ordering of the copper intercalant. Unlike conventional purely electronic charge-density-wave states which form, reform, and disappear on picosecond scales as the temperature is changed, once it forms the observed structure in Cu-MoO3 is stable indefinitely over a very large temperature range (30 °C to the decomposition temperature of 450 °C). Nanosecond-scale heating to ˜380-400 °C produced a completely different structure, replacing the disordered as-fabricated Cu-MoO3 with a much more crystallographically ordered metastable state that, according to a precession electron diffraction reconstruction, resembles the original MoO3 lattice apart from an asymmetric distortion that appears to expand parts of the van der Waals gaps to accommodate the copper intercalant. Control experiments in Cu-free material exhibited neither transformation, thus it appears the copper is a necessary part of the phase dynamics. This work shows how the combination of high-density metal atom intercalation and heat treatment over a wide range of time scales can produce nanomaterials of high crystalline quality in unique structural states that cannot be accessed through other methods.

  2. Computed tomography imaging spectrometer (CTIS) with 2D reflective grating for ultraviolet to long-wave infrared detection especially useful for surveying transient events

    NASA Technical Reports Server (NTRS)

    Wilson, Daniel W. (Inventor); Maker, Paul D. (Inventor); Muller, Richard E. (Inventor); Mouroulis, Pantazis Z. (Inventor)

    2003-01-01

    The optical system of this invention is an unique type of imaging spectrometer, i.e. an instrument that can determine the spectra of all points in a two-dimensional scene. The general type of imaging spectrometer under which this invention falls has been termed a computed-tomography imaging spectrometer (CTIS). CTIS's have the ability to perform spectral imaging of scenes containing rapidly moving objects or evolving features, hereafter referred to as transient scenes. This invention, a reflective CTIS with an unique two-dimensional reflective grating, can operate in any wavelength band from the ultraviolet through long-wave infrared. Although this spectrometer is especially useful for rapidly occurring events it is also useful for investigation of some slow moving phenomena as in the life sciences.

  3. Computed Tomography Imaging Spectrometer (CTIS) with 2D Reflective Grating for Ultraviolet to Long-Wave Infrared Detection Especially Useful for Surveying Transient Events

    NASA Technical Reports Server (NTRS)

    Wilson, Daniel W. (Inventor); Maker, Paul D. (Inventor); Muller, Richard E. (Inventor); Mouroulis, Pantazis Z. (Inventor)

    2003-01-01

    The optical system of this invention is an unique type of