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IEEE Nuclear Science Symposium / Medical Imaging Conference Record (NSS/MIC) / 19th Room-Temperature Semiconductor X-ray and Gamma-ray Detector Workshop

作者： Mao, Yanfei Zeng, Gengsheng L. Univ Utah Utah Ctr Adv Imaging Res UCAIR Salt Lake City UT 84112 USA Univ Utah Utah Ctr Adv Imaging Res UCAIR Dept Radiol Salt Lake City UT 84108 USA

ISBN: (纸本)9781467320306;9781467320283

Dedicated cardiac SPECT systems have the advantage of high speed and sensitivity at no loss or even a gain in resolution. T he purpose of this paper is to investigate segmented parallel-hole collimation, develop a tailored Maximum-Likelihood expectation-Maximization (ML-EM) algorithm for reconstructing truncated projections, and find the minimal number of view-angles required. We simulated and compared three image configurations, including two segmented-parallel-hole detectors based on the conventional and large detectors, and one small multi-detector. To study the effects of truncation and the number of angular sampling, the number of view-angles was varied from 10 to 60 and the truncation degree increased from 91% to 95%. For each view-angle, the root-mean-square error (RMSE) between the reconstructed image and the phantom was calculated and used to give a measure of the accuracy of the reconstructions. Distortion was observed from the shape difference maps of the heart. A tailored ML-EM algorithm was used in the reconstruction, wherein the true-projection to forward-projection ratios outside of FOV were set to one instead of zero before backprojection. Finally, an NCAT phantom and GAT E Monte Carlo simulation tool were used to verify the conclusions. Computer simulation results show that truncation has little effect on the reconstructed images when sufficient view angles are provided, while it affects the reconstruction with few number of views in terms of reducing contrast and introducing bias to the reconstructions. Based on visual inspection only, 10 view-angles is sufficient to reconstruct the image without shape distortion. To reconstruct both value and shape correctly, 20 view-angles is the minimum requirement for truncated projections. Two segmented conventional detectors are sufficient to reconstruct the image without distortion. Uniform angular sampling gives a considerable improvement in the image quality, but a small rotation is required.

关键词： Monte Carlo methods cardiology expectation-maximisation algorithm image reconstruction image sampling image segmentation mean square error methods medical image processing phantoms single photon emission computed tomography

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Reconstruction of Dose Distribution in In-beam PET for Carbon Therapy

Reconstruction of Dose Distribution in In-beam PET for Carbo...

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IEEE Nuclear Science Symposium / Medical Imaging Conference Record (NSS/MIC) / 19th Room-Temperature Semiconductor X-ray and Gamma-ray Detector Workshop

作者： Kim, Kwangdon Bae, Seungbin Lee, Kisung Chung, Yonghyun An, Sujung Joung, Jinhun Korea Univ Dept Radiol Sci Seoul 136793 South Korea Yonsei Univ Dept Radiol Sci Wonju 220-710 South Korea Nucare Med Syst Inc Seoul 136693 South Korea

ISBN: (纸本)9781467320306;9781467320283

There are two main artifacts in reconstructed images from in-beam positron emission tomography(PET). Unlike generic PET, in-beam PET uses the annihilation photons which occur during heavy ion therapy. Therefore, the geometry of in-beam PET is not a full ring, but a partial ring in order for the hardrons to arrive the tumor without penetration of detector blocks. The partial ring, however, causes truncation in projection data, due to an absence of detector modules in the openings. The other is ring artifact caused by the gaps between detector modules which can be also founded in generic PET. In this study, we aim to investigate the effect of gaps in reconstructed images and propose possible solutions to compensate the artifacts. We acquired the data by GATE v6.1 with initial ion energies 170,290, 350AMeV of carbon beams. Each detector module consists of a 13 by 13 LYSO crystal array. The dimension of a crystal was 4mm * 4mm * 20 mm and the radius of inner circle of the gantry was 15cm. In case of truncation error, we proposed to get prior knowledge of the location where annihilations occur. Similar to time-of-flight PET reconstruction, we applied a Gaussian distribution to system matrix, through the width of hardron beams in our back-projection routine. Then expectation maximization(EM) updates were performed iteratively. In case of the latter, to fill the gaps, we used the iterative discrete-cosine transform(DCT) domain method proposed by Uygar Tuna, Sari Peltonen, and Ulla Ruotsalainen. The results show that the proposed method can compensate to some extent the error caused by insufficient angle coverage and we can see the path of hardron beam by proposed method. However, we found other artifacts induced beyond the Bragg peak positions the number of iterations increased. We will improve the proposed algorithm to get more accurate dose distribution.

关键词： Gaussian distribution carbon discrete cosine transforms dosimetry expectation-maximisation algorithm image reconstruction ion beam applications medical image processing positron emission tomography radiation therapy tumours

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Characterization of transient wandering tones by dynamic modeling of fractional-Fourier features 25

Characterization of transient wandering tones by dynamic mod...

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IEEE International Conference on Acoustics, Speech, and Signal Processing

作者： Ainsleigh, PL Kehtarnavaz, N USN Undersea Warfare Ctr Newport RI 02841 USA

ISBN: (纸本)0780362934

A novel approach is presented for characterizing transient wandering tones. These signals ale segmented and approximated as time series with piecewise linear instantaneous frequency and piecewise constant amplitude. Frequency I ate, center frequency, and energy features are estimated in each segment of data using chirped autocorrelations and the fractional Fourier transform. These features ale tracked across segments using linear dynamical models whose parameters are estimated using an expectation-maximization algorithm. A new cross-covariance estimator for adjacent states of the dynamical model is given. The feature extraction/tracking algorithm is used to characterize a measured marine-mammal localization. Application of the representation algorithm to signal classification is discussed.

关键词： signal classification kinetic model dynamic models Piecewise Segments characteristic energy expectation-maximisation algorithm

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Image gradient histogram's fitting and calculation

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JOURNAL OF ENGINEERING-JOE 2018年第1期2018卷 45-48页

作者： Ding, Chang Dong, Lili Xu, Wenhai Dalian Maritime Univ Sch Informat Sci & Technol Dept Informat & Commun Engn Dalian 116026 Peoples R China

The gradient is an important property in an image. According to the characteristics of image gradient histogram (image gradient magnitude distribution), Gamma distribution model is near to the actual distribution, so Gamma mixture model is used to fit natural image gradient distribution. First, an image can be divided into edge region and non-edge region on the aspect of the gradient;the authors assume that each region obeys sub-Gamma distribution with different parameters. Then, expectation maximisation (EM) algorithm is used to estimate the parameters of each part. Finally, the accuracy of the fitting result of the entire gradient distribution is verified by the correlation coefficient and the validity of the estimated gradient magnitude distribution of non-edge region and edge region is verified by the edge-detection experiment with different threshold. This work can select Canny edge-detector high threshold adaptively, which can improve algorithm automatic level.

关键词： image enhancement gradient methods gamma distribution edge detection expectation-maximisation algorithm image gradient histogram Gamma distribution model Gamma mixture model EM algorithm gradient magnitude distribution Canny edge-detector

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Data-Driven Quality Monitoring and Fault Detection for Multimode Nonlinear Processes

Data-Driven Quality Monitoring and Fault Detection for Multi...

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51st IEEE Annual Conference on Decision and Control (CDC)

作者： Haghani, Adel Ding, Steven X. Esch, Jonas Hao, Haiyang Univ Duisburg Essen Inst Automat Control & Complex Syst AKS D-47057 Duisburg Germany

ISBN: (纸本)9781467320665

This paper addresses the problem of quality monitoring and fault detection in nonlinear processes which are working in different operating points. For such processes the statistical model which is obtained from process data is different from one operating point to another, due to nonlinearities and set-point changes. Therefore the classical methods for quality monitoring and fault detection, e. g. partial least squares (PLS), may not be suitable. To this end, a new approach is proposed based on the modeling of nonlinear process as a piecewise linear parameter varying system, considering the behavior of the plant in each operating point as linear time invariant with different parameters in each operating point. The expectation-maximization (EM) algorithm is used to model the process as a finite mixture of Gaussian components and based on the identified model a Bayesian inference strategy is developed to detect the faults which influence the product quality. Finally, the usefulness of the proposed method is demonstrated on a laboratory continuous stirred tank heater (CSTH) setup.

关键词： Gaussian processes belief networks control nonlinearities expectation-maximisation algorithm fault diagnosis heating elements industrial plants inference mechanisms least squares approximations nonlinear control systems piecewise linear techniques product quality quality control statistical analysis tanks (containers) variable structure systems

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Noise Benefits in the expectation-Maximization algorithm: NEM Theorems and Models

Noise Benefits in the Expectation-Maximization Algorithm: NE...

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International Joint Conference on Neural Networks (IJCNN)

作者： Osoba, Osonde Mitaim, Sanya Kosko, Bart Univ Southern Calif Inst Signal & Image Proc Dept Elect Engn Los Angeles CA 90089 USA Thammasat Univ Dept Elect & Comp Engn Fac Engn Bangkok 12120 Thailand

ISBN: (纸本)9781424496365

We prove a general sufficient condition for a noise benefit in the expectation-maximization (EM) algorithm. Additive noise speeds the average convergence of the EM algorithm to a local maximum of the likelihood surface when the noise condition holds. The sufficient condition states when additive noise makes the signal more probable on average. The performance measure is Kullback relative entropy. A Gaussian-mixture problem demonstrates the EM noise benefit. Corollary results give other special cases when noise improves performance in the EM algorithm.

关键词： Gaussian noise Gaussian-mixture problem Kullback relative entropy Maximum likelihood estimation NEM model NEM theorem Noise Noise measurement Probability density function Random variables Signal processing algorithms Stochastic resonance additive noise speeds entropy expectation-maximisation algorithm expectation-maximization algorithm noise benefits

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Image Segmentation Using a Spatially Correlated Mixture Model with Gaussian Process Priors

Image Segmentation Using a Spatially Correlated Mixture Mode...

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2nd IAPR Asian Conference on Pattern Recognition (ACPR)

作者： Kurisu, Kosei Suematsu, Nobuo Iwata, Kazunori Hayashi, Akira Hiroshima City Univ Grad Sch Informat Sci Hiroshima Japan

ISBN: (纸本)9781479921904

Finite mixture modeling has been widely used for image segmentation. However, since it takes no account of the spatial correlation among pixels in its standard form, its segmentation accuracy can be heavily deteriorated by noise in images. To improve segmentation accuracy in noisy images, the spatially variant finite mixture model has been proposed, in which a Markov Random Filed (MRF) is used as the prior for the mixing proportions and its parameters are estimated using the expectation-Maximization (EM) algorithm based on the maximum a posteriori (MAP) criterion. In this paper, we propose a spatially correlated mixture model in which the mixing proportions are governed by a set of underlying functions whose common prior distribution is a Gaussian process. The spatial correlation can be expressed with a Gaussian process easily and flexibly. Given an image, the underlying functions are estimated by using a quasi EM algorithm and used to segment the image. The effectiveness of the proposed technique is demonstrated by an experiment with synthetic images.

关键词： Gaussian processes finite mixture models image segmentation image segmentation Mixture models Gaussian processes Mix proportioning Gauss images Prior distribution expectation-maximisation algorithm Noise

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Factor Model Estimation By Using the Alpha-EM algorithm

Factor Model Estimation By Using the Alpha-EM Algorithm

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IEEE Global Conference on Signal and Information Processing (GlobalSIP)

作者： Jia, Tengjie SUNY Stony Brook Quantitat Finance Appl Math & Stat Stony Brook NY 11794 USA

ISBN: (纸本)9781479902484

in this paper, we present the alpha-EM algorithm for factor model estimation for given sample covariance. The alpha-EM includes the traditional log-EM as its proper subset. Since we use log-EM for factor analysis, however, it is shown that alpha-EM can also be used on factor analysis and more important the convergence speed of the alpha-EM is much faster than log-EM. It also allows us to choose different alphas to achieve the fastest convergence speed and more accurate factor model estimation.

关键词： expectation-maximisation algorithm Factor analysis Proper subset algorithms sample covariance Converge fast speed

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Estimating the number of Active Flows from Sampled Packets

Estimating the number of Active Flows from Sampled Packets

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13th IEEE/IFIP Network Operations and Management Symposium

作者： Cheng, Guang Southeast Univ Sch Comp Sci & Engn Nanjing 210096 Peoples R China

ISBN: (纸本)9781467302685

A flow is active during a measurement period if it sends at least one packet. It is essential to control resource consumption in network monitoring by traffic sampling, so most high-end routers provide sampling network traffic function. The number of original flow is an important metrics to many network applications such as congestion control and network security. In this paper, we present a EUF algorithm that can accurately infer the number of original flow from the sampled packet traffic. Using the EUF algorithm, the number of unsampled flows can be estimated by an iteration method based on random sampling, and then the number of original flows can be precisely estimated according to both the number of the sampled flows and the unsampled flow. The EUF algorithm is also compared with the EM algorithm using multiple traffic traces collected from a Tier-1 ISP backbone networks. The result shows that the EUF algorithm is superior to EM and can provide highly accurate estimation on the number of the original flow.

关键词： Packet Traffic expectation-maximisation algorithm network applications Flow Network security Resource utilization highly accurate Random sampling sampling network

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A Dynamical System Model for Neural Tracking of Speech with EEG

A Dynamical System Model for Neural Tracking of Speech with ...

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6th International IEEE EMBS Conference on Neural Engineering (NER)

作者： Rajaram, Siddharth Lalor, Edmund C. Shinn-Cunningham, Barbara G. Boston Univ Ctr Computatinal Neurosci & Neural Technol Boston MA 02215 USA Trinity Coll Dublin Trin Ctr Bioengn &Trin Dublin Ireland

ISBN: (纸本)9781467319690

In this paper we present a linear dynamical system to model the ongoing neural response, measured by EEG, while a listener is selectively attending a speech stream that is presented in a mixture. In our state-space formulation, the latent state variables represent the activity of the underlying neural substrates and the ongoing neural dynamics are captured by a multivariate autoregressive model with exogenous inputs (MVARX model). The observation model projects these neural sources onto the EEG montage. System identification is performed using a novel regularized expectation maximization (EM) algorithm for linear dynamical systems. The model was able to correctly identify which of two simultaneously presented speech streams was attended in roughly 85% of one minute long test trials, averaged over all subjects.

关键词： autoregressive processes electroencephalography expectation-maximisation algorithm medical signal processing neurophysiology speech speech processing

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