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conference on image reconstruction from incomplete data V

作者： Guizar-Sicairos, Manuel Fienup, James R. Univ Rochester Inst Opt Rochester NY 14627 USA

ISBN: (纸本)9780819472960

Measuring a series of far-field intensity patterns from an object, taken after a, transverse translation of the object with respect to a known illumination pattern, has been shown to make the problem of image reconstruction by phase retrieval much more robust. However, previously reported reconstruction algorithms [Phys. Rev. Lett. 93, 023903 (2004)] rely oil an accurate knowledge of the translations and illumination pattern for a successful reconstruction. We developed a nonlinear optimization algorithm that allows optimization over the translations and illumination pattern, dramatically improving the reconstructions if the system parameters are inaccurately known [Opt. Express 16, 7264 (2008)]. In this paper we compare reconstructions obtained with these algorithms under realistic experimental scenarios.

关键词： Phase retrieval image reconstruction techniques inverse scattering coherent x-ray imaging

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Exploiting image sparsity in parallel magnetic resonance imaging (pMRI)

Exploiting image sparsity in parallel magnetic resonance ima...

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conference on image reconstruction from incomplete data V

作者： Wu, Bing Millane, R. P. Watts, Richard Bones, Philip J. Univ Canterbury Dept Elect & Comp Engn Computat Imaging Grp Christchurch 1 New Zealand Univ Canterbury Dept Phys & Astron Christchurch New Zealand

A hybrid method is presented which allows the acceleration of parallel MR imaging through combining the ideas of compressed sensing with inversion of the imaging matrix. A novel data reordering is employed to enhance ... 详细信息

ISBN: (纸本)9780819472960

关键词： Fourier transforms image restoration Magnetic resonance imaging Computer programming Compressed sensing Receivers Signal processing data acquisition Atrial fibrillation Chemical elements

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image reconstruction in electron microscopy

Image reconstruction in electron microscopy

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conference on image reconstruction from incomplete data V

作者： Zheng, Yili Lee, Seunghee Doerschuk, Peter C. Purdue Univ W Lafayette IN 47907 USA

ISBN: (纸本)9780819472960

Maximum likelihood statistical algorithms are described for estimating the 3-D variation of the electron scattering intensity of biological objects from cryo electron microscopy images of multiple instances of the object. Three virus objects, two spherical and one helical, are considered. Solution of the maximum likelihood problem by expectation maximization algorithms or by direct maximization of the log likelihood requires large scale computing and end-to-end codesign of biological problem formulation, statistical models, algorithms, and software design and implementation have contributed to achieving practical results.

关键词： Cryo electron microscopy cryo EM heterogeneous spherical virus homogeneous spherical virus helical virus maximum likelihood statistical reconstruction 3-D reconstruction tomography nonlinear reconstruction expectation maximization algorithm

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Evaluation of Surrogate data Quality in Sinogram-Based CT Metal-Artifact Reduction

Evaluation of Surrogate Data Quality in Sinogram-Based CT Me...

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conference on image reconstruction from incomplete data V

作者： Oehler, May Kratz, Baerbel Knopp, Tobias Mueller, Jan Buzug, Thorsten M. Univ Lubeck Inst Med Engn D-23538 Lubeck Germany

ISBN: (纸本)9780819472960

In this work different surrogate data strategies to reduce metal artifacts in reconstructed CT images are tested. Inconsistent sinogram projection data caused by e.g. beam hardening are the origin of metal artifacts in the reconstructed images. The goal of this work is to replace this inconsistent projection data by artificially generated data. Therefore, here, two I D interpolation strategies, a directional interpolation based upon the sinogram 'flow' and a I D interpolation by means of the non-equispaced fast Fourier transform are compared to a fully 2D method based upon the idea of image inpainting. Due to the fact that the artificially generated data never perfectly fit the gap inside the projection data caused by the inconsistencies, those repaired sinogram data are reconstructed using a weighted Maximum Likelihood Expectation Maximization algorithm called lambda-MLEM algorithm. In this way, the artificially generated data, still contaminated with residual inconsistencies, are weighted less during reconstruction.

关键词： Metal artifact reduction MLEM reconstruction image inpainting non-equispaced fast Fourier transformation computed tomography surrogate data strategy

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The promise of new PET image reconstruction

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PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS 2008年第2期24卷 49-56页

作者： Reader, Andrew J. Univ Manchester Sch Chem Engn & Analyt Sci Manchester M60 1QD Lancs England

image reconstruction in positron emission tomography (PET) is conventionally regarded as the algorithm applied to the acquired data to produce images used for estimation of physiological parameters, or to determine the presence of disease. There are numerous approaches to image reconstruction, and the method chosen has a significant impact on the utility of PET. The use of iterative image reconstruction algorithms and the use of resolution modelling ("resolution recovery") are two specific advances from recent years which have demonstrated marked improvements in image quality. This paper considers three main aspects of PET image reconstruction in which there are still promising possibilities for further advance: (i) full consideration of the raw acquired PET data (with minimal, pre-processing), (ii) careful selection of the parameters to estimate and (iii) accurate definition of the system matrix, which maps the parameters to the measurement space. Specific examples for these three areas include (i) the full use of timing, position and energy information, (ii) selecting physiological parameters as the unknowns to estimate and (iii) using Monte Carlo simulation to model. the PET scanner and patient, in conjunction with time-dependent MRI or CT anatomical information to render the model more accurate. Present computational constraints mean that limited but practical methods have to be used, which to some extent compromise the full capabilities of image reconstruction in all of the aforementioned areas of promise. Nonetheless, this paper comments on possible ways forward without being overly concerned about the current limitations. (C) 2008 Published by Elsevier Ltd on behalf of Associazione ItaLiana di Fisica Medica.

关键词： image reconstruction positron emission tomography

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Robust statistical extension to TRELLIS motion correction in MRI

Robust statistical extension to TRELLIS motion correction in...

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conference on image reconstruction from incomplete data V

作者： Bones, Philip J. Maclaren, Julian R. Univ Canterbury Dept Elect & Comp Engn Computat Imaging Grp Christchurch 1 New Zealand Univ Hosp Med Phys Dept Diagnost Radiol Freiburg Germany

ISBN: (纸本)9780819472960

Bulk motion occurring during the acquisition of data in magnetic resonance imaging (MRI) causes serious artifacts in the reconstructed images. The paper presents an extension to TRELLIS, a recently developed method of detecting and correcting for bulk motion. While TRELLIS detects and corrects for bulk translation and rotation. only rotation is considered here. Accurate determination of the relative orientations of overlapping strips of k-space is demonstrated using a robust statistical approach to aid least squares estimation. reconstructions for both simulated and actual MRI acquisitions are presented.

关键词： Magnetic resonance imaging Signal to noise ratio data acquisition Motion estimation Statistical analysis image restoration reconstruction algorithms Computer simulations Error analysis Fourier transforms

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Turbulence Profiling for Long Range Surveillance Imaging

Turbulence Profiling for Long Range Surveillance Imaging

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conference on image reconstruction from incomplete data V

作者： Lambert, Andrew Fraser, Donald Bowman, David Brandon, Shane Davies, John Australian Def Force Acad Univ New S Wales Sch Informat Technol & Elect Engn Canberra ACT 2600 Australia

ISBN: (纸本)9780819472960

We report a test of the turbulence found in real-world, horizontal imaging under high magnification. The experiment creates a double "star" on a test chart for use both with a SLODAR turbulence profiling instrument, and simultaneously imaged using a very fast camera to determine traditional seeing parameters. Effects on a similarly located image are investigated to determine the observed effects on the imagery as a function of turbulence location.

关键词： image restoration turbulence profiling surveillance imaging SLODAR

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Iterative projection algorithms for reconstructing compact binary images

Iterative projection algorithms for reconstructing compact b...

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conference on image reconstruction from incomplete data V

作者： Lo, V. L. Millane, R. P. Univ Canterbury Dept Elect & Comp Engn Computat Imaging Grp Christchurch 1 New Zealand

ISBN: (纸本)9780819472960

An algorithm is described for reconstructing compact binary images from limited Fourier amplitude data. This problem arises in macromolecular crystallography where one wishes to reconstruct the molecular envelope from crystal x-ray diffraction amplitudes using a solvent contrast series. Such data are the amplitude of the Fourier transform of all object that has a constant electron density within the boundary of the molecule and zero outside. The image is thus binary and compact, but, the data are available only within a limited resolution range in Fourier space and are undersampled. The problem is solved Using all iterative projection algorithm;a class of algorithm used to solve inverse problems for which the solution is subject to a, number of constraints that, represent a priori information and the data. Unfortunately, these algorithms experience convergence difficulties if one or more of the constraints are non-convex, which is the case for all the constraint's in this problem. We solve the problem by constructing appropriate projection operators and implementing the difference map projection algorithm. Simulations axe used to study convergence behaviour of the algorithm.

关键词： Phase retrieval image reconstruction Iterative Projection Algorithms X-ray crystallography

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Processing of the Astronomical image data obtained from UWFC Optical Systems

Processing of the Astronomical Image Data obtained from UWFC...

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conference on image reconstruction from incomplete data V

作者： Rerabek, Martin Pata, Petr Koten, Pavel Czech Tech Univ Fac Elect Engn Dept Radioelect Tech 2 Prague 16627 6 Czech Republic Acad Sci Czech Republ Astron Inst Dept Interplanetary Matter Ondrejov 25165 Czech Republic

ISBN: (纸本)9780819472960

This paper deals with simulation and modeling of the optical systems used in astronomy and their transfer characteristics. It is especially focused to the WFC (Wide-Field Camera) and UWFC (Ultra Wide-Field Camera) SV (Space Variant) optical systems. The properties of UWFC astronomical systems along with specific visual data in astronomical images contribute to complicated evaluation of acquired image data. There is an experiment for estimate the optical aberration of optical systems described in this paper. The results of different deconvolution algorithms, which are used with partially variant model of UWFC optical system, are demonstrated in this paper.

关键词： image processing PSF Zernike polynomial Optical aberration Space variant Deconvolution algorithm

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A preliminary investigation of using prior information for potentially improving image reconstruction in few-view CT

A preliminary investigation of using prior information for p...

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Medical Imaging 2008 conference

作者： Cho, Seungryong Sidky, Emil Y. Bian, Junguo Pelizzari, Charles A. Pan, Xiaochuan Univ Chicago Dept Radiol Chicago IL 60637 USA Univ Chicago Dept Radiat & Cellular Oncol Chicago IL 60637 USA

ISBN: (纸本)9780819470973

There exists a strong need to reconstruct computed tomographic (CT) images with practically useful quality from a small number of projections in image-guided radiation therapy: for lowering radiation dose delivered to the subject, for shortening the imaging time, and for reducing the imaging-configuration complexity. We have recently developed an iterative image reconstruction algorithm based on total-variation (TV) minimization from incomplete projection data in CT. In numerical studies with a variety of incomplete projection-data sets including truncated data, reduced scan range, and sparse sampling, the developed algorithm seems to yield reasonable reconstruction, as compared to some of the existing algorithms, such as algebraic reconstruction technique (ART) and expectation minimization (EM). The TV-based algorithm begins in general with a uniform image as an initial guess, and goes through iteration steps to minimize the image TV subject to satisfying the given incomplete projection data. In image-guided radiation therapy (IGRT), a patient usually undergoes CT scanning for treatment. planning, which can provide the reference image for image guidance. Therefore, we propose a TV-based algorithm with a priori information in few-view CT for IGRT, in an attempt to further reduce the number of projections needed for image reconstruction from what the TV-based algorithm uses when no a priori information is included. In this work, we report the initial results of a preliminary numerical study that we have conducted to demonstrate this approach.

关键词： reconstruction algorithms Computed tomography Expectation maximization algorithms image restoration Algorithm development Radiotherapy CT reconstruction image quality Detection and tracking algorithms image registration

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