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Assessing denoising strategies to increase signal to noise ratio in spinal cord and in brain cortical and subcortical regions

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JOURNAL OF INSTRUMENTATION 2018年第2期13卷 C02028-C02028页

作者： Maugeri, L. Moraschi, M. Summers, P. Favilla, S. Mascali, D. Cedola, A. Porro, C. A. Giove, F. Fratini, M. IRCCS Fdn Santa Lucia Via Ardeatina 306-354 I-00179 Rome Italy Ctr Fermi Museo Storico Fis Piazza Viminale 1 I-00184 Rome Italy Ctr Studi & Ric Enrico Fermi Piazza Viminale 1 I-00184 Rome Italy Univ Modena & Reggio Emilia Dept Biomed Metab & Neural Sci Via Giuseppe Campi 287 I-41125 Modena Italy CNR NANOTEC Piazzale Aldo Moro 2 I-00185 Rome Italy

Functional Magnetic Resonance Imaging (fMRI) based on Blood Oxygenation Level Dependent (BOLD) contrast has become one of the most powerful tools in neuroscience research. On the other hand, fMRI approaches have seen limited use in the study of spinal cord and subcortical brain regions (such as the brainstem and portions of the diencephalon). Indeed obtaining good BOLD signal in these areas still represents a technical and scientific challenge, due to poor control of physiological noise and to a limited overall quality of the functional series. A solution can be found in the combination of optimized experimental procedures at acquisition stage, and well-adapted artifact mitigation procedures in the data processing. In this framework, we studied two different data processing strategies to reduce physiological noise in cortical and subcortical brain regions and in the spinal cord, based on the aCompCor and RETROICOR denoising tools respectively. The study, performed in healthy subjects, was carried out using an ad hoc isometric motor task. We observed an increased signal to noise ratio in the denoised functional time series in the spinal cord and in the subcortical brain region.

关键词： data processing methods MRI (whole body, cardiovascular, breast, others), MR-angiography (MRA)

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Representative elementary volume in limestone sample

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JOURNAL OF INSTRUMENTATION 2018年第10期13卷 C10003-C10003页

作者： de Araujo, O. M. O. Sharma, K. V. Machado, A. S. Santos, T. M. P. Ferreira, C. G. Straka, R. Tavares, F. W. Lopes, R. T. Univ Fed Rio de Janeiro Nucl Instrumentat Lab BR-24210240 Rio De Janeiro Brazil AGH Univ Sci & Technol Fac Met Engn & Ind Comp Sci Dept Heat Engn & Environm Protect Al Mickiewicza 30 PL-30059 Krakow Poland Univ Fed Rio de Janeiro Chem Engn Program BR-24210240 Rio De Janeiro Brazil

The study of fluid flow through porous media with complex characteristics is of great relevance in applications related to exploration of oil and gas reserves. With growth of computer simulation combined with the use of reconstructed images it became increasingly common to use a representative volume, popularly known as REV. The use of a REV is necessary since the total volume of reconstructed image is too heavy to be loaded into simulation software, increasing data processing time and in some cases making total volume simulation impracticable. However, when investigating different rocks types, some main issues are addressed related to REV, such as how reliable is representative volume compared to the total sample volume. Quantitative and qualitative results such as porosity and permeability vary with the region chosen for the REV as well as configuration of pore connected vary depending on region, showing the importance in choosing a region so that REV represents total results of the sample.

关键词： Computing (architecture , farms ,GRID for recording , storage ,archiving and distribution of data) Simulation methods and programs data processing methods data reduction methods

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Investigation of image distortion due to MCP electronic readout misalignment and correction via customized GUI application

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JOURNAL OF INSTRUMENTATION 2018年第4期13卷 C04028-C04028页

作者： Vitucci, G. Minniti, T. Tremsin, A. S. Kockelmann, W. Gorini, G. Univ Milano Bicocca Dept Phys I-20125 Milan Italy Rutherford Appleton Lab STFC ISIS Facil Harwell OX11 0QX Berks England Univ Calif Berkeley Space Sci Lab Berkeley CA 94720 USA

The MCP-based neutron counting detector is a novel device that allows high spatial resolution and time-resolved neutron radiography and tomography with epithermal, thermal and cold neutrons. Time resolution is possible by the high readout speeds of similar to 1200 frames/sec, allowing high resolution event counting with relatively high rates without spatial resolution degradation due to event overlaps. The electronic readout is based on a Timepix sensor, a CMOS pixel readout chip developed at CERN. Currently, a geometry of a quad Timepix detector is used with an active format of 28 x 28 mm(2) limited by the size of the Timepix quad (2 x 2 chips) readout. Measurements of a set of high-precision micrometers test samples have been performed at the Imaging and Materials Science & Engineering (IMAT) beamline operating at the ISIS spallation neutron source (U.K.). The aim of these experiments was the full characterization of the chip misalignment and of the gaps between each pad in the quad Timepix sensor. Such misalignment causes distortions of the recorded shape of the sample analyzed. We present in this work a post-processing image procedure that considers and corrects these effects. Results of the correction will be discussed and the efficacy of this method evaluated.

关键词： Pattern recognition cluster finding calibration and fitting methods data processing methods Analysis and statistical methods

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Pulsed-neutron imaging by a high-speed camera and center-of-gravity processing

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JOURNAL OF INSTRUMENTATION 2018年第1期13卷 C01038-C01038页

作者： Mochiki, K. Uragaki, T. Koide, J. Kushima, Y. Kawarabayashi, J. Taketani, A. Otake, Y. Matsumoto, Y. Su, Y. Hiroi, K. Shinohara, T. Kai, T. Tokyo City Univ Dept Nucl Safety Engn Setagaya Ku 1-28-1 Tamazutsumi Tokyo 1588557 Japan Tokyo City Univ Cooperat Major Nucl Energy Setagaya Ku 1-28-1 Tamazutsumi Tokyo 1588557 Japan RIKEN Ctr Adv Photon 2-1 Hirosawa Wako Saitama 3510198 Japan CROSS 162-1 Shirakata Tokai Ibaraki 3191106 Japan JAEA J PARC Ctr 2-4 Shirakata Tokai Ibaraki 3191195 Japan

Pulsed-neutron imaging is attractive technique in the research fields of energy-resolved neutron radiography and RANS (RIKEN) and RADEN (J-PARC/JAEA) are small and large accelerator-driven pulsed-neutron facilities for its imaging, respectively. To overcome the insuficient spatial resolution of the conunting type imaging detectors like mu NID, nGEM and pixelated detectors, camera detectors combined with a neutron color image intensifier were investigated. At RANS center-of-gravity technique was applied to spots image obtained by a CCD camera and the technique was confirmed to be effective for improving spatial resolution. At RADEN a high-framerate CMOS camera was used and super resolution technique was applied and it was recognized that the spatial resolution was futhermore improved.

关键词： Image processing Neutron radiography data processing methods Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs etc)

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Improving image reconstruction algorithm for rotating modulation collimators using a variance stabilizing transform

Improving image reconstruction algorithm for rotating modula...

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18th International Workshop on Radiation Imaging Detectors

作者： Shin, Y. Kim, G. Lee, G. Seoul Natl Univ Sci & Technol Dept Elect & IT Media Engn Seoul South Korea Sejong Univ Dept Nucl Engn Seoul South Korea

Arotating modulation collimator (RMC) is an indirect imaging technique that has proven useful for remote radiation source detection. While it was initially invented for detecting sources in a far field, a recent development by Kowash has shown the feasibility of the RMC for detecting mid-range sources. However, their image reconstruction algorithm often produces spurious source estimates in pixels where no source exists. In this paper, we propose to improve the RMC image quality using a variance stabilizing transform. The transform reduces the inhomogeneous Poisson noise in the RMC data. In our simulation study, the proposed algorithm could reconstruct RMC images without misleading artifacts.

关键词： data processing methods Image filtering Search for radioactive and fissile materials Inspection with gamma rays

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Development of Pileup Recovery Algorithms by Peak Detection Method of Digital Gamma Ray Spectroscopy 34

Development of Pileup Recovery Algorithms by Peak Detection ...

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34th National Radio Science Conference (NRSC)

作者： Ouda, Manar M. El Tokhy, Mohamed S. Amal-Eldin, Mohamed Hashima, Sherief Ziedan, Nesreen Mahmoud, Imbaby I. Egyptian Atom Energy Author Nucl Res Ctr Engn Dept Cairo Egypt Zagazig Univ Comp & Syst Engn Dept Fac Engn Zagazig Egypt

ISBN: (纸本)9781509046096

The Pulse pile-up in gamma ray spectroscopy is a severe problem because it degrades both energy resolution and detection efficiency, especially at high count rates. This paper presents two algorithms for signal recovery of peak pile up. These algorithms depend on experimental acquisition of gamma radiation signals with analog to digital converter at sampling rate 16MS/s. The first algorithm depends on a peak detection method that determines the peaks' parameters, which are recorded into a two rows matrix representing the amplitude and position of the peaks. The second algorithm depends on a peak sensitivity method, which determines the location of the maximum peaks using a local extreme method. The variance between each two adjacent points are calculated to find indices of nonzero elements that are larger than zero to determine the maximum amplitude of each peak. The resultant peaks correspond to peak location. These two methods are evaluated by comparing not only their parameters but also their fitting error. Moreover, the influence of these algorithms on the obtained spectrums are analyzed and evaluated. The results show that the second algorithm outperforms the performance of the first one due to the efficient recovery of overlapping peaks.

关键词： Digital signal processing gamma-ray detection High-count-rate spectrometry pileup correction data processing methods

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Bigdata and computing challenges in high energy and nuclear physics

BigData and computing challenges in high energy and nuclear ...

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International Conference on Instrumentation for Colliding Beam Physics

作者： Klimentov, A. Grigorieva, M. Kiryanov, A. Zarochentsev, A. Brookhaven Natl Lab Dept Phys Upton NY 11973 USA Natl Res Ctr Kurchatov Inst BigData Lab Ac Kurchatov Sq Moscow Russia Tomsk Natl Polytech Univ Inst Cybernet 84-3 Sovetskaya Tomsk Russia Petersburg Nucl Phys Inst NRC KI IT Lab Gatchina Russia St Petersburg State Univ Phys Dept Ul Ulianovskaya 23 St Petersburg Russia

In this contribution we discuss the various aspects of the computing resource needs experiments in High Energy and Nuclear Physics, in particular at the Large Hadron Collider. This will evolve in the future when moving from LHC to HL-LHC in ten years from now, when the already exascale levels of data we are processing could increase by a further order of magnitude. The distributed computing environment has been a great success and the inclusion of new super-computing facilities, cloud computing and volunteering computing for the future is a big challenge, which we are successfully mastering with a considerable contribution from many super-computing centres around the world, academic and commercial cloud providers. We also discuss R&D computing projects started recently in National Research Center "Kurchatov Institute"

关键词： Computing (architecture, farms, GRID for recording, storage, archiving, and distribution of data) Software architectures (event data models, frameworks and databases) data processing methods

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After-pulsing and cross-talk comparison for PM1125NS-SB0 (KETEK), S10362-11-100C (HAMAMATSU) and S13360-3050CS (HAMAMATSU)

After-pulsing and cross-talk comparison for PM1125NS-SB0 (KE...

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International Conference on Instrumentation for Colliding Beam Physics

作者： Oleynikov, V. Porosev, V. Budker Inst Nucl Phys Lavrentiev Ave 11 Novosibirsk 630090 Russia

Silicon photomultipliers (SiPMs) are extensively used in different fields now. They exceed photomultiplier tubes in the quantum efficiency, size and resistance to magnetic field. However, because of structure features, their dark noise rate is higher and they have additional sources of noise: cross-talk and after-pulsing. In addition, these parameters may be temperature dependent. In this article we present results of an evaluation of the dark noise rate, probabilities of cross-talk and after-pulses at different voltages and temperatures for two modern SiPMs: S13360-3050CS(HAMAMATSU) and PM1125NS-SB0 (KETEK). For comparison, the data for a previous-generation SiPM, S10362-11-100C (HAMAMATSU), are presented. To find these parameters, we performed a waveform analysis to determine the amplitude and time distributions of the pulses generated by a SiPM without an external light source. We evaluated the temperature and voltage dependences of these parameters. The measured cross-talk probability for PM1125NS-SB0 and S13360-3050CS at their optimal operating voltage is about 6%. It is two times smaller than that for S10362-11-100C. The fast component of the after-pulsing probability for PM1125NS-SB0 and S13360-3050CS is about 10%, which is also almost 2 times smaller than the sum of the fast and slow components of the after-pulsing probability for S10362-11-100C. The dark noise rate for S13360-3050CS at 20 degrees C is just 45 kHz/mm(2) in comparison with 60 kHz/mm(2) for PM1125NS-SB0.

关键词： Analysis and statistical methods data processing methods Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs etc)

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Feasibility study of direct spectra measurements for Thomson scattered signals for KSTAR fusion-grade plasmas

Feasibility study of direct spectra measurements for Thomson...

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18th International Symposium on Laser-Aided Plasma Diagnostics

作者： Park, K. -R. Kim, K. -H. Kwak, S. Svensson, J. Lee, J. Ghim, Y. -C. Korea Adv Inst Sci & Technol Dept Nucl & Quantum Engn Daejeon South Korea Max Planck Inst Plasma Phys Teilinst Greifswald Greifswald Germany Natl Fus Res Inst Daejeon South Korea

Feasibility study of direct spectra measurements of Thomson scattered photons for fusion-grade plasmas is performed based on a forward model of the KSTAR Thomson scattering system. Expected spectra in the forward model are calculated based on Selden function including the relativistic polarization correction. Noise in the signal is modeled with photon noise and Gaussian electrical noise. Electron temperature and density are inferred using Bayesian probability theory. Based on bias error, full width at half maximum and entropy of posterior distributions, spectral measurements are found to be feasible. Comparisons between spectrometer-based and polychromator-based Thomson scattering systems are performed with varying quantum efficiency and electrical noise levels.

关键词： Analysis and statistical methods data processing methods Plasma diagnostics charged-particle spectroscopy Spectrometers

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A comparative study of reconstruction methods applied to Neutron Tomography

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JOURNAL OF INSTRUMENTATION 2018年第6期13卷 C06006-C06006页

作者： Micieli, D. Minniti, T. Formoso, V Kockelmann, W. Gorini, G. Univ Calabria Dipartimento Fis Via Pietro Bucci I-87036 Cosenza Italy Univ Milano Bicocca Dipartimento Fis G Occhialini Piazza Sci 3 I-20126 Milan Italy Rutherford Appleton Lab STFC ISIS Facil Didcot OX11 0QX Oxon England Univ Calabria Sistema Tecnol MaTeRiA Via Pietro Bucci I-87036 Cosenza Italy

Neutron Tomography (NT) is an established technique to non-destructively investigate the inner structure of a wide range of objects. The major drawback of NT is the long acquisition time required to perform a tomographic scan compared to an X-ray Computed Tomography (CT) scan, due to the limited particle flux of the existing neutron sources. Therefore, in the NT field there is great interest in the reduction of scan time, dictated by the high neutrons production cost, aimed at optimizing the beamtime use at neutron imaging beamlines. A way for decreasing the total scan time is to reduce the number of projections. Generally, iterative reconstruction methods have advantages over analytical algorithms, such as the widely used Filtered Back-Projection (FBP), when data are noisy and limited. This research is focused on the comparative analysis of different reconstruction techniques, aimed at finding the data processing procedure suitable for NT, that reduces the scan time without reduction of the reconstructed image quality. For this purpose, a phantom sample was analysed by means of a white beam NT performed at the IMAT beamline, ISIS Neutron Source, U.K. Experimental data were used to test the performances of the FBP algorithm and different iterative reconstruction methods as a function of the number of projections and for different setups of the imaging system. The reconstructed images were quantitatively compared in terms of image quality indexes and the benefits of iterative methods for the limited data problem are discussed.

关键词： Computerized Tomography (CT) and Computed Radiography (CR) data processing methods Inspection with neutrons

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