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Recent developments on techniques for differential phase imaging at the medical beamline of ELETTRA

JOURNAL OF INSTRUMENTATION 2013年第6期8卷 C06001-C06001页

作者： Arfelli, F. Pelliccia, D. Cedola, A. Astolfo, A. Bukreeva, I. Cardarelli, P. Dreossi, D. Lagomarsino, S. Longo, R. Rigon, L. Sodini, N. Menk, R. H. Univ Trieste Dept Phys I-34127 Trieste Italy Ist Nazl Fis Nucl Sez Trieste I-34127 Trieste Italy Monash Univ Sch Phys Clayton Vic 3800 Australia Ist Foton & Nanotecnol CNR I-00156 Rome Italy Ist Nazl Fis Nucl Sez Roma 1 I-00185 Rome Italy Australian Synchrotron Co Ltd Clayton Vic 3168 Australia Univ Ferrara Dept Phys I-44121 Ferrara Italy Ist Nazl Fis Nucl Sez Ferrara I-44121 Ferrara Italy Sincrotrone Trieste SCpA Trieste Italy UOS CNR Ist Processi Chim Fisici I-00185 Rome Italy

Over the last decade different phase contrast approaches have been exploited at the medical beamline SYRMEP of the synchrotron radiation facility Elettra in Trieste, Italy. In particular special focus has been drawn to analyzer based imaging and the associated imaging theory and processing. Analyzer based Imaging (ABI) and Diffraction Enhanced Imaging (DEI) techniques have been successfully applied in several biomedical applications. Recently it has been suggested to translate the acquired knowledge in this field towards a Thomson Backscattering Source (TBS), which is presently under development at the Frascati National Laboratories of INFN (Istituto Nazionale di Fisica Nucleare) in Rome, Italy. Such source is capable of producing intense and quasi-monochromatic hard X-ray beams. For the technical implementation of biomedical phase imaging at the TBS a grating interferometer for differential phase contrast imaging has been designed and successfully tested at SYRMEP beamline.

关键词： data processing methods Image reconstruction in medical imaging X-ray radiography and digital radiography (DR) X-ray mammography and scinto- and MRI-mammography

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Ring artifacts removal from synchrotron CT image slices

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JOURNAL OF INSTRUMENTATION 2013年第6期8卷 C06006-C06006页

作者： Wei, Zhouping Wiebe, Sheldon Chapman, Dean Univ Saskatchewan Saskatoon SK S7N 5E5 Canada Saskatoon Hlth Reg Saskatoon SK S7K 5T6 Canada

Ring artifacts can occur in reconstructed images from x-ray Computerized Tomography (CT) as full or partial concentric rings superimposed on the scanned structures. Due to the data corruption by those ring artifacts in CT images, qualitative and quantitative analysis of these images are compromised. In this paper, we propose to correct the ring artifacts on the reconstructed synchrotron radiation (SR) CT image slices. The proposed correction procedure includes the following steps: (1). transform the reconstructed CT images into polar coordinates;(2) apply discrete two-dimensional (2D) wavelet transform to the polar image to decompose it into four image components: low pass band image component, as well as the components from horizontal, vertical and diagonal details bands;(3). apply 2D Fourier transform to the vertical details band image component only, since the ring artifacts become vertical lines in the polar coordinates;(4). apply Gaussian filtering in Fourier domain along the abscissa direction to suppress the vertical lines, since the information of the vertical lines in Fourier domain is completely condensed to that direction;(5). perform inverse Fourier transform to get the corrected vertical details band image component;(6). perform inverse wavelet transform to get the corrected polar image;(7). transform the corrected polar image back to Cartesian coordinates to get the CT image slice with reduced ring artifacts. This approach has been successfully used on CT data acquired from the Biomedical Imaging and Therapy (BMIT) beamline in Canadian Light Source (CLS), and the results show that the ring artifacts in original SR CT images have been effectively suppressed with all the structure information in the image preserved.

关键词： Image filtering data processing methods Image processing Computerized Tomography (CT) and Computed Radiography (CR)

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A method for the near real-time production of quasi-definitive magnetic observatory data

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EARTH PLANETS AND SPACE 2013年第11期65卷 1363-1374页

作者： Clarke, Ellen Baillie, Orsi Reay, Sarah J. Turbitt, Chris W. British Geol Survey Edinburgh EH9 3LA Midlothian Scotland

Magnetic observatory data are widely used in the derivation of time-varying magnetic field models, often in combination with satellite magnetic data, when available. Traditionally the definitive observatory results are used, the availability of which can often lag those of the satellite data by months and even years. The recently defined quasi-definitive observatory data type has been introduced to meet the need to provide observatory data suitable for use in field modeling in a more rapid time frame and for producing Level 2 products planned for the upcoming European Space Agency Swarm mission. A method for producing quasi-definitive data is presented and the essential steps described. To evaluate the method, provisional data published on a next day basis since 2000 are tested against definitive data at five INTERMAGNET observatories. The means and standard deviations of the differences between the candidate quasi-definitive and definitive data are within the accuracy of 5 nT set by INTERMAGNET. Since the tested data were published on-line on a next day basis, they also easily meet the INTERMAGNET requirement of availability within three months. These results demonstrate that prompt production of quasi-definitive data is possible for observatories that already perform to the standards set by INTERMAGNET.

关键词： Geomagnetic observatory quasi-definitive data observatory baselines data processing methods

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Micro-particle image velocimetry measurement of blood flow: validation and analysis of data pre-processing and processing methods

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MEASUREMENT SCIENCE AND TECHNOLOGY 2012年第10期23卷 105302-105302页

作者： Pitts, K. L. Mehri, R. Mavriplis, C. Fenech, M. Univ Ottawa Dept Chem & Biol Engn Ottawa ON K1N 6N5 Canada Univ Ottawa Dept Mech Engn Ottawa ON K1N 6N5 Canada

The intent of this paper is to investigate the application of a pre-processing method previously validated on glycerol to blood flows in microchannels and to compare the accuracy of results obtained when applied to a non-homogeneous fluid such as blood with results from previously applied processing methods for blood data. Comparisons of common processing methods are desired for a clear measure of accuracy in order to make recommendations for various flows. It is hypothesized that increasing the correlation window overlap improves the profile prediction. The amount of correlation window overlap and window shape in the processing of data have a significant effect on the results. Image pre-processing is explored to improve the correlation using the 'image overlapping' which is extended to the case of blood and the blood-specific pre-processing 'base-clipping' or 'thresholding' technique currently applied to blood. Both pre-processing methods are tested with multiple processing methods for two channel geometries: a straight rectangular channel and a Y-channel resulting in a controlled shear flow. The resulting profiles and calculations demonstrate that 'image-overlapping' is found to achieve a profile closer to the predicted theoretical profile than current blood pre-processing methods when both are applied to the same set of data and both are superior to conventional cross-correlation on its own. In all cases, pre-processing decreases the smoothness of the predicted profile. The use of 'image-overlapping' is shown to have greater accuracy when calculating the shear rate at the wall of the channel as well.

关键词： micro-particle image velocimetry data processing methods blood red blood cells cross-correlation image overlapping thresholding

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Toward clinical differential phase contrast mammography: preliminary evaluations and image processing schemes

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JOURNAL OF INSTRUMENTATION 2013年第5期8卷 C05009-C05009页

作者： Stampanoni, M. Wang, Z. Thuering, T. David, C. Roessl, E. van Stevendaal, U. Koehler, T. Trippel, M. Singer, G. Kubik-Huch, R. A. Hohl, M. K. Hauser, N. Paul Scherrer Inst Swiss Light Source CH-5232 Villigen Switzerland Univ Zurich Inst Biomed Engn Zurich Switzerland Swiss Fed Inst Technol Zurich Switzerland Paul Scherrer Inst Lab Micro & Nanotechnol CH-5232 Villigen Switzerland Philips Technol GmbH Hamburg Germany Kantonsspital Baden Inst Pathol CH-5404 Baden Switzerland Kantonsspital Baden Dept Radiol CH-5404 Baden Switzerland Kantonsspital Baden Interdisciplinary Breast Ctr Baden Dept Gynecol & Obstet CH-5404 Baden Switzerland

Phase contrast and scattering-based X-ray imaging are very promising tools for medical diagnostics because they are able to provide additional and complementary information to traditional absorption-based methods. In this work, we discuss the investigation of three native breast samples with a grating interferometer equipped with a conventional X-ray tube, the full study being published in ref. [1]. We briefly introduce a method to fuse absorption, differential phase and scattering signals into a unique image with improved diagnostic contents. Our approach yields complementary and inaccessible information on the electron density distribution and the small-angle scattering power of the sample which could potentially answer clinically relevant, yet unresolved questions such as the capability to unequivocally discern between (pre-) malignant changes and post-operative scars or to distinguish cancer-invaded regions within healthy tissue.

关键词： X-ray mammography and scinto- and MRI-mammography Image filtering data processing methods Medical-image reconstruction methods and algorithms computer-aided so

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Improving the spatial resolution of soft X-ray detection using an Electron-Multiplying Charge-Coupled Device

Improving the spatial resolution of soft X-ray detection usi...

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14th International Workshop on Radiation Imaging Detectors

作者： Soman, M. R. Hall, D. J. Tutt, J. H. Murray, N. J. Holland, A. D. Schmitt, T. Raabe, J. Schmitt, B. Open Univ Ctr Elect Imaging E2v Milton Keynes MK7 6AA Bucks England Paul Scherrer Inst CH-5232 Villigen Switzerland

The Super Advanced X-ray Emission Spectrometer (SAXES) is an instrument at the Swiss Light Source designed for Resonant Inelastic X-ray Scattering with an energy resolution (E/Delta E) better than 12000 at 930 eV. Improvements to the instrument have been predicted that could allow the energy resolution to be improved by a factor of two. To achieve this, the spatial resolution of the detector (currently a Charge-Coupled Device, CCD) over which the energy spectrum is dispersed would have to be improved to better than 5 mu m. X-ray photons with energies between a few hundred to a few thousand electron volts primarily interact within the field-free region of back-illuminated CCDs, where each photon forms an electron cloud that diffuses isotropically before reaching the depleted region close to the electrodes. Each photon's electron cloud is likely to be detected as an event with signal split across multiple pixels. Analysing these split events using centroiding techniques allows the photon's interaction position to be determined to a sub-pixel level. PolLux is a soft X-ray microspectroscopy endstation at the Swiss Light Source that can focus 200 eV to 1200 eV X-rays to a spot size of approximately 20 nm. Previous studies using data taken with a linear scan across the centre of a pixel in 3 mu m steps predicted an improved resolution by applying centroiding techniques and using an Electron-Multiplying CCD (EM-CCD). In this study, a full 2D map of the centroiding accuracy in the pixel is presented, formed by rastering in two dimensions across the image plane in single micron steps. The improved spatial resolution from centroiding events in the EM-CCD in all areas of the pixel over the standard CCD is attributed to the improved signal to noise ratio provided by the multiplication register even at high pixel readout speeds (tens of MHz).

关键词： X-ray detectors Spectrometers Solid state detectors data processing methods

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Polarimetric spectra analysis for tokamak pitch angle measurements

Polarimetric spectra analysis for tokamak pitch angle measur...

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16th International Symposium on Laser-Aided Plasma Diagnostics

作者： Ko, J. Chung, J. Lange, A. G. G. de Bock, M. F. M. Natl Fus Res Inst Taejon 305806 South Korea Eindhoven Univ Technol Dept Appl Phys NL-5600 MB Eindhoven Netherlands

Measurements of the internal magnetic field structures using conventional polarimetric approaches are considered extremely challenging in fusion-reactor environments whereas the information on current density profiles is essential to establish steady-state and advance operation scenarios in such reactor-relevant devices. Therefore, on ITER a hybrid system is proposed for the current density measurements that uses both polarimetry and spectral measurements. The spectrum-based approaches have been tested in the Korea Superconducting Tokamak Advanced Research (KSTAR) during the past two plasma campaigns. As such, KSTAR is a test-bed for the proposed ITER hybrid system. Measurements in the plasma core are based on the motional Stark effect (MSE) spectrum of the neutral beam emission. For the edge profiles, the Zeeman effect (ZE) acting on the lithium emission spectrum of the newly installed (2013) Lithium-beam-diagnostic is exploited. The neutral beam emission spectra, complicated by the multi-ion-source beam injection, are successfully fitted making use of the data provided by the Atomic data and Analysis Structure (ADAS) database package. This way pitch angle profiles could be retrieved from the beam emission spectra. With the same spectrometer/CCD hardware as on MSE, but with a different wavelength range and different lines of sight, the first ZE spectrum measurements have been made. The Zeeman splitting comparable to and greater than the instrumental broadening has been routinely detected at high toroidal field operations (similar to 3 Tesla).

关键词： Plasma diagnostics - interferometry, spectroscopy and imaging Polarimeters Polarisation data processing methods

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The online data pre-processing for CBM-TOF

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JOURNAL OF INSTRUMENTATION 2013年第02期8卷 P02002-P02002页

作者： Xiang, C. Z. Herrmann, N. Deppner, I. Loizeau, P. -A. Wisniewski, K. Zhang, Y. P. Zhou, D. C. Fruehauf, J. Linev, S. Manz, S. Mueller, W. F. J. Cent China Normal Univ Coll Phys Sci & Technol Wuhan 430079 Peoples R China Cent China Normal Univ Minist Educ Key Lab Quark & Lepton Phys Wuhan 430079 Peoples R China Heidelberg Univ Inst Phys D-69120 Heidelberg Germany GSI Helmholtz Ctr Heavy Ion Res GmbH D-64291 Darmstadt Germany Kirchhoff Inst Phys D-69120 Heidelberg Germany

The Compressed Baryonic Matter (CBM) experiment will operate a free streaming data acquisition system. In order to optimize the data bandwidth and to achieve high performance, a data pre-processing is designed in the readout chain for the CBM-TOF detector. In this paper, we present the design of this module, results of its simulations and preliminary in-beam results which obtained with a test setup on the proton beam at the COSY accelerator in Julich, Germany.

关键词： data processing methods Online farms and online filtering Control and monitor systems online

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Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

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JOURNAL OF INSTRUMENTATION 2013年第05期8卷 P05008-P05008页

作者： Lukic, S. Bozovic-Jelisavcic, I. Pandurovic, M. Smiljanic, I. Univ Belgrade Vinca Inst Nucl Sci Belgrade 11001 Serbia

Procedures for correcting the beam-beam effects in luminosity measurements at CLIC at 3 TeV center-of-mass energy are described and tested using Monte Carlo simulations. The angular counting loss due to the combined Beamstrahlung and initial-state radiation effects is corrected based on the reconstructed velocity of the collision frame of the Bhabha scattering. The distortion of the luminosity spectrum due to the initial-state radiation is corrected by deconvolution. At the end, the counting bias due to the finite calorimeter energy resolution is numerically corrected. To test the procedures, BHLUMI Bhabha event generator, and Guinea-Pig beam-beam simulation were used to generate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. The systematic effects of the beam-beam interaction on the luminosity measurement are corrected with precision of 1.4 permille in the upper 5% of the energy, and 2.7 permille in the range between 80 and 90% of the nominal center-of-mass energy.

关键词： data processing methods Beam dynamics Calorimeters

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Improved sensitivity at synchrotrons using edge illumination X-ray phase-contrast imaging

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JOURNAL OF INSTRUMENTATION 2013年第6期8卷 C06002-C06002页

作者： Diemoz, P. C. Endrizzi, M. Zapata, C. E. Bravin, A. Speller, R. D. Robinson, I. K. Olivo, A. UCL Dept Med Phys & Bioengn London WC1E 6BT England European Synchrotron Radiat Facil F-38043 Grenoble France London Ctr Nanotechnol London WC1H 0AH England Res Complex Harwell Didcot OX11 0FA Oxon England

The application of the X-ray phase-contrast 'edge illumination' principle to the highly coherent beams available at synchrotron radiation facilities is presented here. We show that, in this configuration, the technique allows achieving unprecedented angular sensitivity, of the order of few nanoradians. The results are obtained at beamlines of two different synchrotron radiation facilities, using various experimental conditions. In particular, different detectors and X-ray energies (12 keV and 85 keV) were employed, proving the flexibility of the method and the broad range of conditions over which it can be applied. Furthermore, the quantitative separation of absorption and refraction information, and the application of the edge illumination principle in combination with computed tomography, are also demonstrated. Thanks to its extremely high phase sensitivity and its flexible applicability, this technique will both improve the image quality achievable with X-ray phase-contrast imaging and allow tackling areas of application which remain unexplored until now.

关键词： Image reconstruction in medical imaging X-ray radiography and digital radiography (DR) Computerized Tomography (CT) and Computed Radiography (CR) data processing methods

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