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reconstruction algorithms for nonstandard CT scanner designs

Journal of Medical Systems 1982年第6期6卷 555-567页

作者： Herman, Gabor T. From the Medical Image Processing Group Department of Radiology University of Pennsylvania Philadelphia 19104 Pennsylvania 3400 Spruce Street United States

Data collected by a CT scanner provide estimates of line integrals of the X-ray attenuation distribution in a cross section of the human body. The lines along which integrals are collected are determined by the positions of the source-detector pairs during the data collection. Since only the lines are important (and not the positions of the source and the detector on the line), essentially the same data may be collected by scanners of very different design. In this article we illustrate that in certain situations the problem of reconstruction from data collected by a CT scanner of a new (and nonstandard) design can be "reduced" to the problem of reconstruction from data collected by a CT scanner for which the problem has already been solved. The "reduction" involves identifying values of free parameters in the old design (such as the radius of the circle in which the source rotates), which would make the geometry of data collection essentially identical to that of the proposed new design. Since reconstruction algorithms for the old design already exist, they can be applied without any change to the data collected by the new scanner. In other words, the problem of finding a reconstruction algorithm for a nonstandard mode of data collection can sometimes be solved by describing a (virtual) machine of standard design whose reconstruction algorithms are immediately applicable to the data collected by the nonstandard machine. The method is demonstrated on a recently proposed concept for transforming a radiotherapy simulator into a CT scanner. © 1982 Plenum Publishing Corporation.

关键词： Data Collection Attenuation Human Body Free Parameter reconstruction algorithm

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reconstruction algorithms for laboratory microCT/microXRF system

Reconstruction algorithms for laboratory microCT/microXRF sy...

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Conference on Developments in X-Ray Tomography VII

作者： Liu, Xuan Bruyndonckx, Peter Sasov, Alexander SkyScan NV B-2550 Kontich Belgium

ISBN: (纸本)9780819483003

An integrated microCT/microXRF system has been designed and built at SkyScan. The two sub-systems are aligned. The microCT provides 3D morphological information of the sample, which can be also used for attenuation correction during microXRF reconstruction. The microXRF, based on a pin-hole collimator and a photon-counting energy-sensitive 2D-detector, obtains 2D projections of 3D chemical composition inside the sample with 50-70 microns spatial resolution. The reconstruction of 3D microXRF scans is challenging because of very low photon counting statistics due to limited power of laboratory x-ray sources and the strong self-absorption of the low-energy fluorescence photons. We have developed a maximum-likelihood expectation-maximization (ML-EM) algorithm based on Poisson model. This algorithm has proven to be rather robust and good reconstructions have been obtained with sample scans. Regularization is necessary to achieve stable reconstruction. One method is to apply smoothing between iterations. Two different smoothing kernels have been evaluated: 3D symmetric Gaussian kernel and minimization of total variation. For further improvement, a multi-ray resolution recovery technique has been evaluated. The self-absorption is currently compensated by a simplified method: the correction coefficients are pre-calculated and obtained by forward-projecting the attenuation map for both the primary X-rays and the fluorescence photons. The attenuation maps at the energy of fluorescence photons are approximated from the CT image.

关键词： microXRF microCT reconstruction algorithm maximum likelihood attenuation correction total variation

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Random Sampling and reconstruction of Non-Decaying Signals From Weighted Multiply Generated Shift-Invariant Spaces

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MATHEMATICAL METHODS IN THE APPLIED SCIENCES 2025年第8期48卷 9007-9019页

作者： Li, Wei Wang, Jinping Anhui Univ Sci & Technol Sch Math & Big Data Huainan Peoples R China Ningbo Univ Sch Math & Stat Ningbo Peoples R China Guangzhou Coll Appl Sci & Technol Sch Comp Sci Guangzhou Peoples R China

It is a classical assumption in sampling theory that the input signal is square-integrable. However, non-decaying signals are prevalent in science and engineering. They do not decay and even grow at infinity, such as realizations of Brownian and L & eacute;vy processes. In this paper, we consider the problem of random sampling of non-decaying signals from weighted multiply generated shift-invariant spaces. We obtain that with overwhelming probability, the random sampling stability holds uniformly for all non-decaying signals in certain compact subsets of the weighted multiply generated shift-invariant spaces when the sampling size is sufficiently large. Furthermore, we consider a reconstruction algorithm for a subspace of the weighted multiply generated shift-invariant spaces and provide the probability that the algorithm succeeds.

关键词： non-decaying signals random sampling reconstruction algorithm sampling stability shift-invariant spaces

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Nonzero Data-Filtering-Based Photoacoustic Image reconstruction: Both for Microscopy and Tomography

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2025年 74卷

作者： Paramanick, Arijit Samanta, Deepayan Singh, Mayanglambam Suheshkumar Indian Inst Sci Educ & Res Thiruvananthapuram Sch Phys Thiruvananthapuram 695551 Kerala India

Images, not necessarily to be photoacoustic (PA), are conventionally reconstructed from a collection of boundary-measured data that are also comprised of a significantly large percentage of background noisy signals delivering no pertaining information, and thus, the obtainable imaging performance is remarkably degraded. This article presents a novel and unique technique to undertake image reconstruction, taking into account only the selective signals of importance while filtering out the unwanted noisy signals selectively, which immensely enhances the achievable image quality. Quantitative validation studies-both simulations and experiments in diversified samples [agars, leaf veins, and excised tissues (chicken breasts)] using our home-built PA imaging (PAI) modalities both PA tomography (PAT) and PA microscopy (PAM)-demonstrate a significant enhancement in the imaging performance, which are quantified in terms of various statistical parameters of great interest in practical clinical applications, say, signal-to-noise-ratio (SNR) (similar to 25%-94%), contrast ratio (CR) (similar to 164%-189%), axial resolution (similar to 40%-49%), and lateral resolution (similar to 27%-62%).

关键词： Photoacoustic imaging (PAI) photoacoustic microscopy (PAM) photoacoustic tomography (PAT) reconstruction algorithm ultrasonic beamforming

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Redundancy elimination and high resolution algorithm for reconstruction of digital holograms

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OPTIK 2013年第16期124卷 2468-2474页

作者： Pan, Weiqing Zhu, Yongjian Zhejiang Sci & Technol Univ Dept Phys Hangzhou 310023 Zhejiang Peoples R China

A fast and high-resolution reconstruction algorithm with variable resolution increasing ratio and down-sampling ratio is proposed. Since the digital holography requires that the space-bandwidth product of the recording system should be greater than that of the object so as to ensure no loss of information, usually much redundant information and pixels exist in the recorded digital hologram. According to that, we propose utilizing a flexible down-sampling process with variable ratio to eliminate the redundancy. The technical characteristics are analyzed. The validity of this method is shown by both calculations based on theory analysis and experimental results. (C) 2012 Elsevier GmbH. All rights reserved.

关键词： Digital holography reconstruction algorithm Flexible down-sampling Fast and high speed

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Experiments with the nonlinear and chaotic behaviour of the multiplicative algebraic reconstruction technique (MART) algorithm for computed tomography

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PHYSICS IN MEDICINE AND BIOLOGY 2004年第8期49卷 1455-1474页

作者： Badea, C Gordon, R Duke Med Ctr Ctr Vivo Microscopy Durham NC 27710 USA Univ Manitoba Hlth Sci Ctr Dept Radiol Winnipeg MB R3A 1R9 Canada Univ Manitoba Hlth Sci Ctr TRLabs Winnipeg MB R3A 1R9 Canada

Among the iterative reconstruction algorithms for tomography, the multiplicative algebraic reconstruction technique (MART) has two advantages that make it stand out from other algorithms: it confines the image (and therefore the projection data) to the convex hull of the patient, and it maximizes entropy. In this paper, we have undertaken a series of experiments to determine the importance of MART nonlinearity to image quality. Variants of MART were implemented aiming to exploit and exaggerate the nonlinear properties of the algorithm. We introduce the Power MART, Boxcar Averaging MART and Bouncing MART algorithms. Power MART is linked to the relaxation concept. Its behaviour is similar to that of the chaos of a logistic equation. There appears to be an antagonism between increasing nonlinearity and noise in the projection data. The experiments confirm our general observation that regularization as a means of solving simultaneous linear equations that are underdetermined is suboptimal: it does not necessarily select the correct image from the hyperplane of solutions, and so does not maximize the image quality:x-ray dose ratio. Our investigations prove that there is scope to optimize CT algorithms and thereby achieve greater dose reduction.

关键词： convex hull SEPT4 gene X-Ray Computed Tomography Hyperplane chaos general assessment nonlinearity reconstruction algorithm

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3D ECT reconstruction by an improved Landweber iteration algorithm

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FLOW MEASUREMENT AND INSTRUMENTATION 2014年 37卷 92-98页

作者： Yan, Hua Wang, Yi Fan Zhou, Ying Gang Sun, Yan Hui Shenyang Univ Technol Sch Informat Sci & Engn Shenyang 110870 Peoples R China

Electrical capacitance tomography (ED) is a relatively mature non-invasive imaging technique that attempts to map dielectric permittivity of materials. Recently, 3D ECT has gained interest because of its potential to generate volumetric images. The study of a fast and accurate image reconstruction algorithm is a challenge task, especially for 3D reconstruction. In this paper, we propose an improved Landweber iteration algorithm. We incorporate an additional acceleration term into the cost function and apply an adaptive threshold operation to the image obtained in each iteration for reducing artefacts. The algorithm proposed is tested by the noise-free and noise-contaminated capacitance data. Sensitivity matrixes and capacitance data of a 3D ECT sensor are obtained by using the finite element (FE) method. Extensive simulations in 3D reconstruction are carried out. The results verify the effectiveness of these improvements. Both the reconstruction time and the artefacts in the reconstructed image are reduced obviously. The experimental results of 3D reconstruction of objects in the shape of letters U and L confirm the effectiveness of the proposed algorithm further. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Electrical capacitance tomography 3D reconstruction reconstruction algorithm Reducing image artefacts Convergence rate

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Compressive sensing reconstruction for vibration signals based on the improved fast iterative shrinkage-thresholding algorithm

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MEASUREMENT 2019年 142卷 68-78页

作者： Wang, Qiang Meng, Chen Ma, Weining Wang, Cheng Yu, Lei Army Engn Univ Shijiazhuang Campus Shijiazhuang Hebei Peoples R China Luoyang Elect Equipment Test Certer Luoyang Peoples R China

We consider the compressive sensing reconstruction for vibration signals, which are complex due to the harsh working environment. The recent fast iterative shrinkage-thresholding algorithm (FISTA) has paved the way for the signal reconstruction with a low complexity and high efficiency. Unfortunately, when extending to the vibration signals, the current algorithm still has some drawbacks such as the bad reconstruction effect. In this paper, we propose the improved fast iterative shrinkage-thresholding algorithm (IFISTA) to improve the reconstruction effect. Under the new scheme, the reconstruction is promoted by extracting information from the unstable signals in the process of iteration. Then the feature coefficients will be protected from shrinkage during iteration. The effectiveness of the IFISTA is verified by simulated signals and acquired signals. It is showed that the proposed scheme has superior performance in reconstruction and feature protection for vibration signals. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Signal acquisition Data compression Compressive sensing Vibration signals reconstruction algorithm

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Multiview and light-field reconstruction algorithms for 360° multiple-projector-type 3D display

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APPLIED OPTICS 2013年第19期52卷 4419-4425页

作者： Zhong, Qing Peng, Yifan Li, Haifeng Su, Chen Shen, Weidong Liu, Xu Zhejiang Univ State Key Lab Modern Opt Instrumentat Hangzhou 310027 Zhejiang Peoples R China

Both multiview and light-field reconstructions are proposed for a multiple-projector 3D display system. To compare the performance of the reconstruction algorithms in the same system, an optimized multiview reconstruction algorithm with sub-view-zones (SVZs) is proposed. The algorithm divided the conventional view zones in multiview display into several SVZs and allocates more view images. The optimized reconstruction algorithm unifies the conventional multiview reconstruction and light-field reconstruction algorithms, which can indicate the difference in performance when multiview reconstruction is changed to light-field reconstruction. A prototype consisting of 60 projectors with an arc diffuser as its screen is constructed to verify the algorithms. Comparison of different configurations of SVZs shows that light-field reconstruction provides large-scale 3D images with the smoothest motion parallax;thus it may provide better overall performance for large-scale 360 degrees display than multiview reconstruction. (C) 2013 Optical Society of America

关键词： three-dimensional displays reconstruction algorithm Motion Parallax

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Selection of appropriate computed tomographic image reconstruction algorithms for a quantitative multicenter trial of diffuse lung disease

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JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY 2008年第2期32卷 233-237页

作者： Zhang, Jie Bruesewitz, Michael R. Bartholmai, Brian J. McCollough, Cynthia H. Mayo Clin Coll Med Dept Radiol Rochester MN 55905 USA

Objective: To determine the appropriate computed tomographic (CT) image reconstruction algorithms for a quantitative multicenter trial of diffuse lung disease. Methods: Phantom images were reconstructed using relevant reconstruction algorithms from 2 CT manufacturers to measure mean CT numbers and image noise. High-contrast spatial resolution and edge response function were determined for each algorithm. Clinical images of patients with diffuse lung disease were evaluated by a thoracic radiologist in terms of image quality and disease extent. Results: The CT numbers were accurate for most reconstruction algorithms for both manufacturers, although some algorithms with strong midfrequency enhancement altered CT numbers. The Bone (GE) and B46f (Siemens) algorithms provided the higher spatial resolution deemed clinically necessary for imaging diffuse lung disease while preserving CT number accuracy. The extent of diffuse lung disease was strongly dependent on the reconstruction algorithm. Conclusions: A moderately sharp reconstruction algorithm (Bone/B46f) was selected for the evaluation of diffuse lung disease.

关键词： computed tomography (CT) lung reconstruction algorithm diffuse lung disease emphysema

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