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Optimized Filtered Back-Projection Tomographic reconstruction algorithm for the Step-Shift Scanning of a Sample

RESEARCH IN NONDESTRUCTIVE EVALUATION 2019年第3期30卷 179-187页

作者： Ozdiev, Ali Hosenovich Afornu, Bright Kwame Sednev, Dmitry Andreevich Tomsk Polytech Univ Sch Nondestruct Testing & Secur Tomsk Russia

The variety of modern X-ray sources opens possibilities to conduct measurements of a wide range of different specimens. The range includes objects with various properties such as the density, the amount and types of defects, and the size which can significantly change from sample to sample. Due to the development of portable high energy X-ray sources like betatrons, it is now possible to investigate objects of big sizes. Although, the fact that the dimensions of such objects can exceed the dimensions of X-ray setups requires to develop new types of scanning geometries and to adopt the algorithms of reconstruction and visualization. The scanning of an object along its longest dimension is one of the ways for investigating such objects. In this article, we present the step-shift scanning approach and the adaptation of filtered back-projection algorithm for this type of measurement. The developed algorithm allows to obtain the visualization of the whole volume of the object from the combination of all scanning steps or to visualize the separate parts of the object from the truncated dataset.

关键词： X-Ray tomography non-destructive testing reconstruction algorithm scanning approach

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A theoretically exact reconstruction algorithm for helical cone-beam differential phase-contrast computed tomography

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PHYSICS IN MEDICINE AND BIOLOGY 2013年第16期58卷 5421-5432页

作者： Li, Jing Sun, Yi Zhu, Peiping Dalian Univ Technol Sch Informat & Commun Engn Dalian 116023 Liaoning Provin Peoples R China Chinese Acad Sci Inst High Energy Phys Beijing 100049 Peoples R China

Differential phase-contrast computed tomography (DPC-CT) reconstruction problems are usually solved by using parallel-, fan- or cone-beam algorithms. For rod-shaped objects, the x-ray beams cannot recover all the slices of the sample at the same time. Thus, if a rod-shaped sample is required to be reconstructed by the above algorithms, one should alternately perform translation and rotation on this sample, which leads to lower efficiency. The helical cone-beam CT may significantly improve scanning efficiency for rod-shaped objects over other algorithms. In this paper, we propose a theoretically exact filter-backprojection algorithm for helical cone-beam DPC-CT, which can be applied to reconstruct the refractive index decrement distribution of the samples directly from two-dimensional differential phase-contrast images. Numerical simulations are conducted to verify the proposed algorithm. Our work provides a potential solution for inspecting the rod-shaped samples using DPC-CT, which may be applicable with the evolution of DPC-CT equipments.

关键词： reconstruction algorithm Helical algorithms Spiral Cone-Beam Computed Tomography X-Ray Computed Tomography Exact Differential

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A reconstruction algorithm with flexible stencils for anisotropic diffusion equations on 2D skewed meshes

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JOURNAL OF COMPUTATIONAL PHYSICS 2014年 256卷 484-500页

作者： Chang, Lina Inst Appl Phys & Computat Math Natl Key Lab Sci & Technol Computat Phys Beijing 100088 Peoples R China

A new reconstruction algorithm is developed to obtain diffusion schemes with cell-centered unknowns only. The main characteristic of the new algorithm is the flexibility of stencils when the auxiliary unknowns are reconstructed with cell-centered unknowns. The stencils are selected depending on the mesh geometry and discontinuities of diffusion coefficients. Moreover, an explicit expression is derived for interpolating the auxiliary unknowns in terms of cell-centered unknowns, and the auxiliary unknowns can be defined at any point on the edge. The algorithm is applied to construct several new diffusion schemes, whose effectiveness is illustrated by numerical experiments. For anisotropic problems with or without discontinuities, nearly second order accuracy is achieved on skewed meshes. (C) 2013 Elsevier Inc. All rights reserved.

关键词： Diffusion equation Cell-centered scheme reconstruction algorithm Anisotropic Discontinuity

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Effect of reconstruction algorithm on image quality and identification of ground-glass opacities and partly solid nodules on low-dose thin-section CT: Experimental study using chest phantom

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EUROPEAN JOURNAL OF RADIOLOGY 2010年第3期74卷 500-507页

作者： Koyama, Hisanobu Ohno, Yoshiharu Kono, Atsushi A. Kusaka, Akiko Konishi, Minoru Yoshii, Masaru Sugimura, Kazuro Hyogo Kaibara Hosp Dept Radiol Kaibara Tanba 6693395 Japan Kobe Univ Dept Radiol Grad Sch Med Chuo Ku Kobe Hyogo 6500017 Japan

Purpose: The purpose of this study was to assess the influence of reconstruction algorithm on identification and image quality of ground-glass opacities (GGOs) and partly solid nodules on low-dose thin-section CT. Materials and methods: A chest CT phantom including simulated GGOs and partly solid nodules was scanned with five different tube currents and reconstructed by using standard(A) and newly developed (B) high-resolution reconstruction algorithms, followed by visually assessment of identification and image quality of GGOs and partly solid nodules by two chest radiologists. Inter-observer agreement, ROC analysis and ANOVA were performed to compare identification and image quality of each data set with those of the standard reference. The standard reference used 120 mA s in conjunction with reconstruction algorithm A. Results: Kappa values (kappa) of overall identification and image qualities were substantial or almost perfect (0.60 < kappa). Assessment of identification showed that area under the curve of 25 mA reconstructed with reconstruction algorithm A was significantly lower than that of standard reference (p < 0.05), while assessment of image quality indicated that 50 mA s reconstructed with reconstruction algorithm A and 25 mA s reconstructed with both reconstruction algorithms were significantly lower than standard reference (p < 0.05). Conclusion: reconstruction algorithm may be an important factor for identification and image quality of ground-glass opacities and partly solid nodules on low-dose CT examination. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

关键词： Lung High-resolution CT Radiation dose reconstruction algorithm

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CARLEMAN-BASED reconstruction algorithm FOR WAVES

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SIAM JOURNAL ON NUMERICAL ANALYSIS 2021年第2期59卷 998-1039页

作者： Baudouin, Lucie De Buhan, Maya Ervedoza, Sylvain Osses, Axel Univ Toulouse CNRS LAAS CNRS F-31031 Toulouse France Univ Paris Saclay Lab Math Orsay CNRS F-91405 Orsay France Univ Bordeaux F-33400 Talence France CNRS IMB UMR 5251 F-33400 Talence France Univ Chile Dept Ingn Matemat UMI 2807 CNRS FCFM Santiago Chile Univ Chile Ctr Modelamiento Matemat UMI 2807 CNRS FCFM Santiago Chile

We present a globally convergent numerical algorithm based on global Carleman estimates to reconstruct the speed of wave propagation in a bounded domain with Dirichlet boundary conditions from a single measurement of the boundary flux of the solutions in a finite time interval. The global convergence of the proposed algorithm naturally arises from the proof of the Lipschitz stability of the corresponding inverse problem for both sufficiently large observation time and boundary using global Carleman inequalities. The speed of propagation is supposed to be independent of time but varying in space with a trace and normal derivative known at the boundary and belonging to a certain admissible set that limits the speed fluctuations with respect to a given exterior point x(0). In order to recover the speed, we also require a single experiment with null initial velocity and initial deformation having some monotonicity properties in the direction of x-x(0). We perform numerical simulations in the discrete setting in order to illustrate and to validate the feasibility of the algorithm in both one and two dimensions in space. As proved theoretically, we verify that the numerical reconstruction is achieved for any admissible initial guess, even in the presence of small random disturbances on the measurements.

关键词： hyperbolic equation inverse problem reconstruction algorithm Carleman estimates

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BPF-based reconstruction algorithm for multiple rotation-translation scan mode

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Progress in Natural Science:Materials International 2008年第2期18卷 209-216页

作者： Ming Chen,Huitao Zhang,Peng Zhang Computer Tomography Laboratory,Capital Normal University,Beijing 100037,China Computer Tomography Laboratory Capital Normal University Beijing 100037 China

In industrial CT,it is often required to inspect large objects using short line-detectors. To acquire the complete CT data for the scan-ning slice of large objects using short line-detectors,some multi-scan modes have been developed. But the existing methods reconstruct-ing an image from the data scanned by multi-scan modes have to rebin the data into fan-beam or parallel-beam form via data interpolation. The data rebinning process not only increases great computational cost,but also degrades image resolution. In this paper,we propose a backprojection-filtration (BPF)-based reconstruction algorithm for rotation-translation (RT) multi-scan mode. An impor-tant feature of the proposed algorithm is that data rebinning process is not introduced. The simulation results have verified the validity of the proposed algorithm.

关键词： Backprojection-filtration reconstruction algorithm Multiple rotation-translation scan mode Fan-beam

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The reconstruction algorithm used for [⁶⁸Ga]PSMA-HBED-CC PET/CT reconstruction significantly influences the number of detected lymph node metastases and coeliac ganglia

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EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2017年第4期44卷 662-669页

作者： Krohn, Thomas Birmes, Anita Winz, Oliver H. Drude, Natascha I. Mottaghy, Felix M. Behrendt, Florian F. Verburg, Frederik A. RWTH Univ Hosp Aachen Dept Nucl Med Aachen Germany Maastricht UMC Dept Nucl Med Maastricht Netherlands Radiol Inst Aachen Land Wurselen Germany Univ Hosp Giessen & Marburg Dept Nucl Med Marburg Germany Univ Ulm Dept Nucl Med Albert Einstein Allee 23 D-89081 Ulm Germany

To investigate whether the numbers of lymph node metastases and coeliac ganglia delineated on [Ga-68]PSMA-HBED-CC PET/CT scans differ among datasets generated using different reconstruction algorithms. Data were constructed using the BLOB-OS-TF, BLOB-OS and 3D-RAMLA algorithms. All reconstructions were assessed by two nuclear medicine physicians for the number of pelvic/paraaortal lymph node metastases as well the number of coeliac ganglia. Standardized uptake values (SUV) were also calculated in different regions. At least one [Ga-68]PSMA-HBED-CC PET/CT-positive pelvic or paraaortal lymph node metastasis was found in 49 and 35 patients using the BLOB-OS-TF algorithm, in 42 and 33 patients using the BLOB-OS algorithm, and in 41 and 31 patients using the 3D-RAMLA algorithm, respectively, and a positive ganglion was found in 92, 59 and 24 of 100 patients using the three algorithms, respectively. Quantitatively, the SUVmean and SUVmax were significantly higher with the BLOB-OS algorithm than with either the BLOB-OS-TF or the 3D-RAMLA algorithm in all measured regions (p < 0.001 for all comparisons). The differences between the SUVs with the BLOB-OS-TF- and 3D-RAMLA algorithms were not significant in the aorta (SUVmean, p = 0.93;SUVmax, p = 0.97) but were significant in all other regions (p < 0.001 in all cases). The SUVmean ganglion/gluteus ratio was significantly higher with the BLOB-OS-TF algorithm than with either the BLOB-OS or the 3D-RAMLA algorithm and was significantly higher with the BLOB-OS than with the 3D-RAMLA algorithm (p < 0.001 in all cases). The results of [Ga-68]PSMA-HBED-CC PET/CT are affected by the reconstruction algorithm used. The highest number of lesions and physiological structures will be visualized using a modern algorithm employing time-of-flight information.

关键词： Prostate cancer PSMA PET/CT PSMA-HBED-CC reconstruction algorithm Staging

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Enhanced reconstruction algorithm for unidirectional distributed video coding

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IET IMAGE PROCESSING 2009年第6期3卷 329-334页

作者： Weerakkody, W. A. R. J. Fernando, W. A. C. Kondoz, A. M. Univ Surrey Ctr Commun Syst Res Surrey GU2 7XH England

Distributed video coding (DVC) is an emerging video coding technology that utilises the distributed source coding principles to build very low cost video encoders, yet with remarkable error resilience. In the most common DVC framework, the reconstruction function plays a vital role that has a direct impact on the output video quality. In this study, a novel algorithm is proposed for the reconstruction function, particularly focusing on a unidirectional DVC architecture. The proposed technique exploits the variations of the bit error rate of the Wyner-Ziv decoded bit stream and the assumed noise model in the side information stream. The simulation results show that the proposed algorithm yields a significant improvement of the objective and subjective video quality at no additional bit rate cost.

关键词： Video coding Simulation results error-resilience digital video coding Videotapes Noise models side information information flow reconstruction algorithm bit stream

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Generalized reconstruction algorithm for compressed sensing

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COMPUTERS & ELECTRICAL ENGINEERING 2011年第4期37卷 570-588页

作者： Lei, J. N China Elect Power Univ Key Lab Condit Monitoring & Control Power Plant E Minist Educ Beijing 102206 Peoples R China

Compressed sensing (CS) is considered as a promising signal processing technique, and successful applications of the CS theory depend mainly on the accuracy and speed of the reconstruction algorithms. In this paper, a generalized objective functional, which has been developed using the combinational estimation and an extended stabilizing functional, is proposed. An efficient iterative scheme, which integrates the beneficial advantages of the homotopy method, the shuffled frog-leaping (SFL) algorithm and the harmony search (HS) algorithm, is designed for searching a possible global optimal solution. Numerical simulations are implemented to evaluate the numerical performances and effectiveness of the proposed algorithm. Excellent numerical performances and encouraging results are observed. For the cases considered in this paper, a dramatic improvement in the reconstruction accuracy is achieved, which indicates that the proposed algorithm is a promising candidate for solving CS inverse problem. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： algorithms homotopy method Numerical Compressed sensing SFL reconstruction algorithm

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A novel CT reconstruction algorithm for incomplete projection based on information repairment

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OPTICS AND LASERS IN ENGINEERING 2018年第Aug.期107卷 207-213页

作者： Xiao, Yu Xu, Feng Shen, Kang Dong, Bo Hu, Xiaofang Xiao, Tiqiao Univ Sci & Technol China Chinese Acad Sci Key Lab Mech Behav & Design Mat Hefei 230027 Anhui Peoples R China Chinese Acad Sci Shanghai Inst Appl Phys Shanghai Synchrotron Radiat Facil Shanghai Peoples R China

An incomplete projection reconstruction algorithm was proposed in this study. In synchrotron radiation computed tomography (SRCT) of mechanical loading process, shielded projection due to the loading device is the main problem of high-resolution CT reconstruction. Thus, the proposed algorithm was developed based on information repairment considering the continuity of sinogram and slice. The truncated sinogram was estimated using orientation total variation minimization (TVM), which was based on the continuity of projections at adjacent angles in sinogram. Slice rectification was conducted to restrain image distortion, which was based on the continuity of matter contribution. Then, the algorithm was validated by a series of numerical reconstruction experiments. Results showed that the new algorithm could repair the lost boundary and restrain the artifacts. Quantitative comparison of evaluation parameters indicated that the new algorithm worked well when the shielded angle was less than 60 degrees and that satisfactory results could be obtained by approximately 200 times of iteration. Finally, the new algorithm was validated using actual SRCT data and demonstrated effective improvement of reconstruction quality. Therefore, the proposed algorithm may be a suitable method for the in situ SRCT studies of mechanical loading processes.

关键词： Mechanical loads IMAGE DISTORTION X-Ray Computed Tomography sinogram algorithms synchrotron radiation loading device reconstruction algorithm

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