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Time walk correction for TOF-PET detectors based on a monolithic scintillation crystal coupled to a photosensor array

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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2010年第1-3期621卷 595-604页

作者： Vinke, R. Lohner, H. Schaart, D. R. van Dam, H. T. Seifert, S. Beekman, F. J. Dendooven, P. Univ Groningen Kernfys Versneller Inst NL-9747 AA Groningen Netherlands Delft Univ Technol NL-2628 JB Delft Netherlands Univ Med Ctr Utrecht NL-3584 CX Utrecht Netherlands

When optimizing the timing performance of a time-of-flight positron emission tomography (TOF-PET) detector based on a monolithic scintillation crystal coupled to a photosensor array, time walk as a function of annihilation photon interaction location inside the crystal needs to be considered. In order to determine the 3D spatial coordinates of the annihilation photon interaction location, a maximum likelihood estimation algorithm was developed, based on a detector characterization by a scan of a 511 key photon beam across the front and one of the side surfaces of the crystal. The time walk effect was investigated using a 20 mm x 20 mm x 12 mm LYSO crystal coupled to a fast 4 x 4 multi-anode photomultiplier tube (MAPMT). In the plane parallel to the photosensor array, a spatial resolution of 2.4 mm FWHM is obtained. In the direction perpendicular to the MAPMT (depth-of-interaction, DOI), the resolution ranges from 2.3 mm FWHM near the MAPMT to 4 mm FWHM at a distance of 10 mm. These resolutions are uncorrected for the similar to 1 mm beam diameter. A coincidence timing resolution of 358 ps FWHM is obtained in coincidence with a BaF(2) detector. A time walk depending on the 3D annihilation photon interaction location is observed. Throughout the crystal, the time walk spans a range of 100 ps. Calibration of the time walk vs. interaction location allows an event-by-event correction of the time walk. (C) 2010 Elsevier B.V. All rights reserved.

关键词： Positron emission tomography Timing resolution TOF-PET positioning algorithm

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A location algorithm based on Stiefel manifold particle filtering

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CLUSTER COMPUTING-THE JOURNAL OF NETWORKS SOFTWARE TOOLS AND APPLICATIONS 2019年第2期22卷 S4877-S4882页

作者： Yao Jun Wang Zhijin Nanjing Univ Aeronaut & Astronaut Coll Aerosp Engn Nanjing 210016 Jiangsu Peoples R China Shanghai Inst Satellite Engn Dept Sci & Technol Shanghai 201109 Peoples R China

To improve precision of positioning process of spacecraft, with full consideration of light conditions, a kind of spacecraft positioning algorithm for particle filter based on Stiefel manifold was proposed. Firstly, wireless signal tracking model of spacecraft positioning was provided and observation model for moving object positioning was built based on path loss model;secondly, the concept of invariant measure was introduced and particle filter of Stiefel manifold was built to realize improvement of algorithm performance. In addition, it was applied to research on spacecraft positioning;finally, the effectiveness of the proposed model was verified through simulation experiment.

关键词： Stiefel Particle filter Spacecraft positioning algorithm

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A multidimensional scaling framework for mobile location using time-of-arrival measurements

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2005年第2期53卷 460-470页

作者： Cheung, KW So, HC City Univ Hong Kong Dept Elect Comp & Informat Technol Hong Kong Hong Kong Peoples R China

Localization of mobile phones is now a very popular research topic. In this paper, a simple algorithm is devised for mobile location estimation using time-of-arrival measurements of the signal from the mobile station received at three or more base stations, via modifying the classical multidimensional scaling technique, which has been developed for analyzing data obtained from physical, biological, and behavioral science. The bias and variance of the proposed algorithm are also derived. Computer simulations are included to corroborate the theoretical development and to contrast the estimator performance with several conventional approaches as well as the Cramer-Rao lower bound.

关键词： mobile terminal multidimensional scaling positioning algorithm time-of-arrival

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New Virtual Frisch-Grid CdZnTe Detector Design With Sub-Millimeter Spatial Resolution

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IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2014年第5期61卷 2567-2572页

作者： Lee, Kisung Bolotnikov, Aleksey Bae, Seungbin Roy, Utpal Camarda, Giuseppe Petryk, Matthew Cui, Yonggang Hossain, Anwar Yang, Ge Dedic, Vaclav Kim, Kihyun James, Ralph B. Korea Univ Seoul 136701 South Korea Brookhaven Natl Lab Upton NY 11973 USA SUNY Binghamton Binghamton NY 13902 USA Charles Univ Prague CR-11636 Prague Czech Republic

We evaluated the performance of a position-sensitive virtual Frisch-grid (VFG) CdZnTe detector, mm mm mm, via sensing strips on its side surfaces. Once the signals were collected from the anode, and from four or eight strips attached to the detector's sides, we assessed the anode's energy spectra and derived histograms from the side electrodes to evaluate the feasibility of achieving sub-millimeter spatial resolution in the X-Y plane. Using a highly collimated 30-keV X-ray beam at the National Synchrotron Light Source, and applying corrections to the raw data, we determined the photon-interaction points by conventional Anger logic and via a more sophisticated statistics-based positioning (SBP) algorithm. With the VFG detector's current configuration, we achieved a resolution below 1 mm, even for low-energy X-rays.

关键词： CdZnTe Frisch-grid position-sensitive positioning algorithm radiation detector

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Multidimensional scaling approach for node localization using received signal strength measurements

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DIGITAL SIGNAL PROCESSING 2014年 34卷 39-47页

作者： Lin, Lanxin So, H. C. Chan, Frankie K. W. City Univ Hong Kong Dept Elect Engn Hong Kong Hong Kong Peoples R China

Node localization has played an important role in wireless sensor networks. In this paper, cooperative localization using received signal strength (RSS) measurements is addressed. The technique of weighted multidimensional scaling (WMDS) which relies on pairwise distance information between nodes is utilized in our algorithm development. Assuming that the transmit power is available, we first convert the original nonlinear localization problem to a system of linear equations, leading to computational attractiveness. It is also proved that the positioning accuracy of the WMDS solution attains the Cramer-Rao lower bound at sufficiently small noise conditions. Furthermore, the proposed method is extended to the unknown transmit power case by exploiting the ratio of squared distance estimates extracted from the RSS information. The effectiveness of the WMDS approach is demonstrated via comparison with several conventional RSS-based positioning methods. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Node localization Received signal strength positioning algorithm Multidimensional scaling

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Linear Least Squares Approach for Accurate Received Signal Strength Based Source Localization

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2011年第8期59卷 4035-4040页

作者： So, Hing Cheung Lin, Lanxin City Univ Hong Kong Dept Elect Engn Hong Kong 34422290 Hong Kong Peoples R China

A conventional approach for passive source localization is to utilize signal strength measurements of the emitted source received at an array of spatially separated sensors. The received signal strength (RSS) information can be converted to distance estimates for constructing a set of circular equations, from which the target position is determined. Nevertheless, a major challenge in this approach lies in the shadow fading effect which corresponds to multiplicative measurement errors. By utilizing the mean and variance of the squared distance estimates, we devise two linear least squares (LLS) estimators for RSS-based positioning in this paper. The first one is a best linear unbiased estimator while the second is its improved version by exploiting the known relation between the parameter estimates. The variances of the position estimates are derived and confirmed by computer simulations. In particular, it is proved that the performance of the improved LLS estimator achieves Cramer-Rao lower bound at sufficiently small noise conditions.

关键词： Best linear unbiased estimator positioning algorithm received signal strength shadow fading

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PD positioning Method and Experimental Study Based on Circular-shaped Ultrasonic Array Sensors

PD Positioning Method and Experimental Study Based on Circul...

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International Conference on Power System Technology (PowerCon)

作者： Li Yanqing Wang Fei Wang Chuan Hu Weitao Xie Qing Tao Junhan North China Elect Power Univ Baoding Baoding City Hebei Province Peoples R China

ISBN: (纸本)9781479950324

PD ultrasound array positioning method is one of the latest achievements in the field of array sensor technology and array signal processing technology. This method can achieve spatial orientation and on-line monitoring of partial discharge source effectively. Ultrasonic array sensor was developed rapidly in the past forty years, its application involves many areas of military and national such as radar, exploration, sonar, communications, seismology, radio astronomy, biomedical engineering, etc. Previous studies showed that the positioning performance of circular-shaped array sensor is superior to the square, linear array sensor and other forms. Therefore, we undertook in-depth study in allusion to circular-shaped ultrasonic array sensor. Contents of this paper are summed up in the following three aspects. Firstly, this paper developed a circular-shaped ultrasonic array sensor. We carried out a detailed and comprehensive investigation on structures, materials and size parameters of array sensor elements and assemblies, and we combined with the specific characteristics of PD ultrasound signals, then we determine the structure of array sensor elements and its main parameters: the dimensions of probe and tail are Phi 7.8x13mm Phi 5.2x13mm, the frequency range is 70kHz-280kHz, etc. The assembly is made of aviation aluminum materials, its sizes are as follows: length is 50mm, width is 40mm, the cylindrical bores in circular-shaped ultrasonic array sensor assemblies are arranged in a circular ring shape, the diameter of the cylindrical bore is 5.2mm, and the depth of the cylindrical bore is 5mm. We get circular-shaped ultrasonic array sensor by assembling ultrasonic array sensor elements and array sensor assembly. Secondly, since the actual PD ultrasonic signals from electrical equipments are wideband signals, we adopt rotational signal subspace (RSS) algorithm to focus processing, which can reserve the information maximally to realize the direction information accumulat

关键词： partial discharge circular-shaped ultrasound array sensor positioning algorithm experimental system

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HIERARCHICAL DISCRETIZED PURSUIT NONLINEAR LEARNING AUTOMATA WITH RAPID CONVERGENCE AND HIGH-ACCURACY

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 1994年第4期6卷 654-659页

作者： PAPADIMITRIOU, GI COMP TECHNOL INST GR-26110 PATRAIGREECE

In this paper, a new absorbing multiaction learning automaton that is epsilon-optimal is introduced. It is a hierarchical discretized pursuit nonlinear learning automaton that uses a new algorithm for positioning the actions on the leaves of the hierarchical tree. The proposed automaton achieves the highest performance (speed of convergence, central processing unit (CPU) time, and accuracy) among all the absorbing learning automata reported in the literature up to now. Extensive simulation results indicate the superiority of the proposed scheme. Furthermore, it is proved that the proposed automaton is epsilon-optimal in every stationary stochastic environment.

关键词： HIERARCHICAL LEARNING AUTOMATON PURSUIT LEARNING algorithm NONLINEAR OUTPUT FUNCTION EPSILON-OPTIMAL LEARNING AUTOMATION positioning algorithm

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A Smart UAV-Femtocell Data Sensing System for Post-Earthquake Localization of People

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IEEE ACCESS 2020年 8卷 30262-30270页

作者： Avanzato, Roberta Beritelli, Francesco Univ Catania Dept Elect Elect & Comp Engn I-95125 Catania Italy

The paper proposes an intelligent data sensing and geo-localization algorithm, based on an innovative mobile computing system that measures the power level of RF sources through a 2G/5G femtocell-UAV system. In natural disasters (mainly earthquakes and floods) the system can identify any missing persons under the rubble within a range of precision between 1 to 2 meters. In this paper, more specifically, the algorithm allows classifying the terminal even in the presence of obstacles that cause anisotropic propagation of radio signals, through a series of power measurements based on the Reference Signal Received Power (RSRP). An attenuation model that takes into account the different types of materials is introduced, and a method for optimizing the drone's flight path and duration is proposed. The performances, expressed in terms of accuracy in identifying the mobile terminal and in terms of position estimation average error, are evaluated according to the material's density and its attenuation.

关键词： Femtocell UAV system geo-localization technique 2G 5G radio technologies reference signal received power (RSRP) mobile terminal classification positioning algorithm energy consumption

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Detector light response modeling for a thick continuous slab detector

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JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 2008年第7期45卷 634-638页

作者： Miyaoka, Robert S. Joo, Sung-Kwan Lee, Kisung Korea Univ Dept Radiol Sci Seoul 136703 South Korea Univ Washington Dept Radiol Seattle WA 98195 USA Korea Univ Sch Elect Engn Seoul 136701 South Korea

We investigate a method to improve the position decoding for thick crystal versions (i.e., >= 8 mm) of the continuous Miniature crystal element (cMiCE) PET detector by more accurately modeling, the detector light response function (LRF). The LRF for continuous detectors varies with the depth of interaction (DOI) of the detected photon. This variation in LRF can result in a positioning error for two-dimensional positioning algorithms. We explore a method to improve positioning performance by deriving two lookup tables, corresponding to the front and back regions of the crystal. The DETECT2000 simulation package was used to investigate the light response characteristics for a 48.8 mm by 48.8 mm by 10 (8) mill slab of LSO coupled to a 64-channel, flat-panel PMT. The data are then combined to produce the two-dimensional light collection histograms. Light collection histograms that have markedly non-Gaussian distributions are characterized as a combination of two Gaussian functions, where each Gaussian function corresponds to a DOI region of the crystal. The results indicate that modest gains in positioning accuracy are achieved near the central region of the crystal. However, significant improvements in spatial resolution and positioning bias are achieved for the corner section of the detector.

关键词： positioning algorithm light response modeling depth of interaction statistics-based positioning algorithm continuous slab detector continuous crystal positron emission tomography

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