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An improved convex programming model for the inverse problem in intensity-modulated radiation therapy

International Journal of Performability Engineering 2018年第5期14卷 871-884页

作者： Lan, Yihua Zhang, Xingang Zhang, Jianyang Wang, Yang Hung, Chih-Cheng School of Computer and Information Technology Nanyang Normal University Nanyang473061 China Institute of Image Processing and Pattern Recognition Nanyang Normal University Nanyang473061 China Radiology Department Central Hospital of Nanyang Nanyang473061 China Laboratory for Machine Vision and Security Research College of Computing and Software Engineering Kennesaw State University - Marietta Campus 1100 South Marietta Parkway MariettaGA30067-2896 United States

Intensity modulated radiation therapy technology (IMRT) is one of the main approaches in cancer treatment because it can guarantee the killing of cancer cells while optimally protecting normal tissue from complications. Inverse planning, which is the core component of the entire IMRT system, is mainly based on accurate mathematical modeling and associated fast solving methods. In inverse planning, the fluence map optimization, which considers the multi-leaf collimator (MLC) modulation, is the current research focus. Although the hitting constrain problem with the unidirectional movement of leaf-sweeping has been solved, our goal is to solve the hitting constrain problem with the bidirectional movement of leaf-sweeping. In this study, we propose a non-synchronized type to solve the hitting constrain problem with the bidirectional movement of leaf-sweeping schemes for IMRT. In solving this problem, a new mathematical model is proposed under the framework of convex programming. The advantage of the convex model is to avoid the uncertainty and inaccuracy that occurs in the non-convex programming solving process. Experimental results for two clinical testing cases show that under the same condition of total number of monitoring units, the new proposed model produces better dose distribution than those of the total variance and quadratic models. © 2018 Totem Publisher, Inc. All rights reserved.

关键词： Convex optimization

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Simulation of thermal field induced by concave spherical transducer in multi-layer media

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Journal of Central South university 2013年第11期20卷 3166-3170页

作者：丁亚军钱盛友廖志远 Institute of Image Recognition and Computer Vision Hunan Normal University College of Physics and Information Science Hunan Normal University

High intensity focused ultrasound(HIFU)therapy is an effective method in clinical treatment of tumors,in order to explore the bio-heat conduction mechanism of in multi-layer media by concave spherical transducer,temperature field induced by this kind of transducer in multi-layer media will be simulated through solving Pennes equation with finite difference method,and the influence of initial sound pressure,absorption coefficient,and thickness of different layers of biological tissue as well as thermal conductivity parameter on sound focus and temperature distribution will be analyzed,*** results show that the temperature in focus area increases faster while the initial sound pressure and thermal conductivity *** absorption coefficient is smaller,the ultrasound intensity in the focus area is bigger,and the size of the focus area is *** the thicknesses of different layers of tissue change,the focus position changes slightly,but the sound intensity of the focus area will change *** temperature in focus area will rise quickly before reaching a threshold,and then the temperature will keep in the threshold range.

关键词： multi-layer media concave spherical transducer high intensity focused ultrasound thermal field

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Wavelength dependent loss of splice of single-mode fibers

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Journal of Central South university 2013年第7期20卷 1832-1837页

作者： YANG Bo DUAN Ji-an XIE Zheng XIAO Hong-feng State Key Laboratory of High Performance Complex Manufactory (Central South University) Changsha 410083 China Institution of Image Recognition and Computer Vision Hunan Normal University Changsha 410081 China

After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produced by them, and the influences of splicing defects were discussed in detail. The regularities of the effects were studied according to the first order derivation of couple efficiency formula, and a simplified formula for couple efficiency calculation was presented under the circumstance of slight misalignment, with respect to wavelength, 2, and in a good agreement with the theoretical model. The simplified formula provides a new but simple approach to evaluate wavelength dependent couple efficiency of single-mode fibers. Theoretical analyses and numerical calculations show that, when those defects exist, the wavelength produces additional effects on the couple loss that growth of wavelength causes an increase on the couple efficiency for the lateral offset or longitude separation whereas lessens the couple efficiency due to angular misalignment or mode fields mismatching, and that the wavelength degrades the couple efficiency distinctly when λ≥2.5 μm whereas it distorts the couple slightly in range of λ≤2λ≤2 μm.

关键词： wavelength dependent loss couple efficiency single-mode fiber cut-offwavelength

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Research on siplification and extraction technology of apple point cloud

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Journal of Applied Sciences 2013年第18期13卷 3684-3690页

作者： Yang, Hui-Jun He, Dong-Jian Jiang, Shao-Hua Wang, Hua College of Mechanical and Electronic Engineering Northwest A and F University Yang ling Shaan xi China College of Infortion Engineering Northwest A and F University Yang ling Shaan xi China Institute of Image Recognition and Computer Vision Hunan Normal University Changsha Hunan China

Expensive computation, low efficiency and inaccuracy remain a long-standing challenge in extraction of fruit shape from massive background points. Towards these objectives, an improved K-neighborhood adaptive subdivision algorithm is proposed to simplify point clouds for reduction of calculation;an MLS-based local surface fitting is employed for more accurate geometric attributes and a Geometric Similarity-based Augmenter (GSA) recursive process is used for rapid extraction of apple shape. As a result, the optimal subdivision parameters help to reduce the number of apple cells to 3.0% of the original points, a 25% down than the K (4%) neighborhood, the GSA extraction algorithm reduce the number of extracted pear cells by 49.5%. © 2013 Asian Network for Scientific Information.

关键词： Extraction

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Research on segmentation of pear shape from unorganized point clouds

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Journal of Multimedia 2013年第4期8卷 394-401页

作者： Yang, Hui-Jun He, Dong-Jian Li, Linhao Jiang, Shao-Hua College of Mechanical and Electronic Engineering Northwest A and F University Yang ling Shaan xi China College of Information Engineering Northwest A and F University Yang ling Shaan xi China AT and T Labs 200 South Laurel Ave #D4-3C05 Middletown NJ United States Institute of Image Recognition and Computer Vision Hunan Normal University Changsha Hunan China

With the advent of 3D scanner, accurate segmentation of 3D fruit shape from unorganized point clouds has been turned out to be the most challenging task in scientists and engineers in reverse engineering. This paper herein proposes efficient and robust approach to extract pear shape from background. At first, an interactive, non-local denoising algorithm is employed to efficient denoise the pear scans;Second, geometric properties, including normal, variation and curvature, are estimated by covariance analysis;Third, a Recursive Region Increment (RRI) is proposed to add the geometric similarity points to a base set, to generate an ultimate set only including the points of pear shape;Forth, point clouds is linearized for rapidly rending in the post processing. Finally, segmentation algorithm applied on ten range scans of a pear demonstrates that our algorithm reduces the number of pear point clouds by 88.3%, proves the validity and practicability of this method in pear segmentation. © 2013 ACADEMY PUBLISHER.

关键词： Reverse engineering

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Wavelength dependent loss of splice of single-mode fibers

Wavelength dependent loss of splice of single-mode fibers

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第八届全国青年岩土力学与工程会议暨青年华人岩土工程论坛

作者： YANG Bo DUAN Ji-an XIE Zheng XIAO Hong-feng State Key Laboratory of High Performance Complex Manufactory (Central South University) Changsha 41 State Key Laboratory of High Performance Complex Manufactory (Central South University) Changsha 41 Institution of Image Recognition and Computer Vision Hunan Normal University Changsha 410081 Chin

After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produced by them, and the influences of splicing defects were discussed in *** regularities of the effects were studied according to the first order derivation of couple efficiency formula, and a simplified formula for couple efficiency calculation was presented under the circumstance of slight misalignment, with respect to wavelength, λ, and in a good agreement with the theoretical *** simplified formula provides a new but simple approach to evaluate wavelength dependent couple efficiency of single-mode *** analyses and numerical calculations show that, when those defects exist, the wavelength produces additional effects on the couple loss that growth of wavelength causes an increase on the couple efficiency for the lateral offset or longitude separation whereas lessens the couple efficiency due to angular misalignment or mode fields mismatching, and that the wavelength degrades the couple efficiency distinctly when λ≥ 2.5 μm whereas it distorts the couple slightly in range of λc≤λ≤2 μm.

关键词： wavelength dependent loss couple efficiency single-mode fiber cut-off wavelength

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A point feature-based cylindrical image mosaic method

A point feature-based cylindrical image mosaic method

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2nd International Conference on Multimedia Technology, ICMT 2011

作者： Li, Xi Gong, Ping College of Math and Computer Science Hunan Normal University Changsha China Institute of Image Recognition and Computer Vision Hunan Normal University Changsha China

ISBN: (纸本)9781612847740

A cylindrical image mosaic method based on Harris corner feature is proposed in the paper. Firstly, the sequence of photographs taken around 360 degree is projected to cylinder coordinate system, and then the Harris corners are detected by an improved Harris corner detecting algorithm. After the NCC (normalized Cross Correlation) corner matching algorithm performed a rough match, an improved RANSAC (Random Sample Consensus) algorithm is applied twice to remove the mismatched points as far as possible to improve the correct matching ratio. Finally, the image mosaic and fusion are accomplished according to the registration result. Experiments demonstrate that the proposed algorithm has achieved a well result. © 2011 IEEE.

关键词： image enhancement

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A separating algorithm for particle image

A separating algorithm for particle image

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2nd International Conference on Multimedia Technology, ICMT 2011

作者： Liu, Xiangbin Li, Xi Institute of Image Recognition and Computer Vision Hunan Normal University Central South University Changsha China College of Math and Computer Science Hunan Normal University Changsha China

ISBN: (纸本)9781612847740

In the particle images, objects tend to touch, overlap with each other to form clusters. How to separate these clusters into single objects is a vital problem for the counting, feature extraction and analysis in the following process. Separating them by boundary tracking do not need an acute angle and/or the strong density contrast at the points where the objects touched, so it can get a better separating result. But sometimes when the principal axis direction of the cluster is neither horizontal nor vertical, it does not work. For this, a new separating algorithm is presented in the paper. At first, the algorithm calculates the principal axis direction of the cluster, if it is nearly horizontal or vertical then goes on, otherwise it rotates the cluster to make its principal axis direction be horizontal. And then the algorithm performs separating by boundary tracking. Experiments show that the algorithm has achieved a well separating result. © 2011 IEEE.

关键词： Clustering algorithms

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A point feature-based cylindrical image mosaic method

A point feature-based cylindrical image mosaic method

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International Conference on Multimedia Technology

作者： Xi Li Ping Gong College of Math and Computer Science Hunan Normal University Changsha China Institute of Image Recognition & Computer Vision Hunan Normal University Changsha China

ISBN: (纸本)9781612847719

关键词： image registration Feature extraction Transforms image edge detection Correlation Nickel Least squares methods

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A separating algorithm for particle image

A separating algorithm for particle image

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International Conference on Multimedia Technology

作者： Xiangbin Liu Xi Li Institute of Image Recognition & Computer Vision Hunan Normal University Changsha China School of Information Science and Engineering Central South University Changsha China College of Math and Computer Science Hunan Normal University Changsha China

ISBN: (纸本)9781612847719

关键词： Clustering algorithms Algorithm design and analysis image segmentation Heuristic algorithms Feature extraction Transforms Arrays

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