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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Shaojie Tang Xuanqin Mou Qiong Xu Yanbo Zhang Hengyong Yu Institute of Image Processing & Pattern Recognition Xi''an Jiaotong University Xi'an Shaanxi China Department of Radiology Emory University School of Medicine Atlanta GA USA Department of Radiology Division of Radiologic Sciences Wake Forest University Health Sciences Winston-Salem NC 27157 USA

In the medical diagnostic computed tomography (CT) systems, the x-ray tube usually emits photons with a polychromatic spectrum, resulting in beam hardening artifacts in the reconstructed images. Although the bone correction method is extensively used to compensate for the beam hardening artifacts, its performance crucially depends on the empirical choice of a scaling factor. To overcome this shortcoming, here we propose two adaptive correction methods, which utilize the Helgasson-Ludwig (H-L) consistency condition to determine the optimal scaling factor and the corresponding coefficient vector. Our numerical simulation results demonstrate the effectiveness of the proposed methods.

关键词： Bones X-ray imaging image reconstruction Computed tomography Biomedical imaging Detectors

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Study on the Method of image Restoration in the Environment of Dust

Study on the Method of Image Restoration in the Environment ...

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International Conference on Wireless Communications, Networking and Mobile Computing (WiCom)

作者： Yuanyu Wang Yuanzong Li Tianxu Zhang Department of Computer Fundamental Education Taiyuan University Of Technology Taiyuan China College of Mechanical Engineering Taiyuan University Of Technology Taiyuan China Institute of Pattern Recognition and A.I State Key Laboratory of Image Processing and Intelligent Control HuaZhong University of Science and Technology Wuhan China

In order to solve the problem of image degradation caused by dust environments, an image degradation model considering multiple scattering factors caused by dust was first established using the first-order multiple scattering method. Then, a dark channel prior principle was applied to present an image restoration algorithm based on the image degradation model. Finally, GA optimization algorithm was applied to optimize the atmospheric light and the exposure parameters. This optimization algorithm was established according to the criterion of the image evaluation based on kirsch operator with automatic threshold. By using the method an optimistic result of image restoration was obtained. The experimental results have shown that the method not only enhanced luminance and contrast, but also discovered more detail edges information. The method provided a foundation for target recognition in the dust environments.

关键词： image edge detection image restoration Scattering Degradation Gallium Atmospheric modeling Genetic algorithms

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Evaluating deformation patterns of the thoracic aorta in gated CTA sequences

Evaluating deformation patterns of the thoracic aorta in gat...

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IEEE International Symposium on Biomedical Imaging

作者： Ernst Schwartz Roman Gottardi Johannes Holfeld Christian Loewe Martin Czerny Georg Langs Computational Image Analysis and Radiology Lab (CIR) Medical University of Vienna Austria Pattern Recognition and Image Processing Group University of Technology Vienna Austria Division of Cardiothoracic Surgery Department of Surgery Medical University of Vienna Austria Division of Interventional Radiology Department of Radiology Medical University of Vienna Austria Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology USA

ISBN: (纸本)9781424441259;9781424441266

Cardiovascular interventions in the region of the aortic isthmus such as stent-grafting and vessel transposition introduce substantial changes in the deformation properties of the affected vessels. The changes play a fundamental role in the long-term prognosis for any such treatment, but are only poorly understood to date. We explore a fully automated method to quantify the deformation patterns of the thoracic aorta in gated computed tomography sequences. The aorta is segmented by a level set approach that accurately identifies the vessel lumen in each frame of the sequence. Consequently, landmarks on the vessel wall in each frame are registered using a probabilistic method. This allows for the measurement of global and local deformation properties. We evaluate our method on synthetic datasets and report first results of its application on real world data.

关键词： Biomedical imaging image segmentation Radiology Cardiology Surgery Computed tomography Level set Electrocardiography Pathology Deformable models

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Automatic segmentation of bladder in CT images

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第2期10卷 239-246页

作者： Feng SHI Jie YANG Yue-min ZHU Institute of Image Processing and Pattern Recognition Shanghai Jiao Tong University Shanghai 200240 China CREATIS. LNSA of Lyon University of Lyon 1 Villeurbanne France

Segmentation of the bladder in computerized tomography(CT) images is an important step in radiation therapy planning of prostate cancer. We present a new segmentation scheme to automatically delineate the bladder contour in CT images with three major steps. First,we use the mean shift algorithm to obtain a clustered image containing the rough contour of the bladder,which is then extracted in the second step by applying a region-growing algorithm with the initial seed point selected from a line-by-line scanning process. The third step is to refine the bladder contour more accurately using the rolling-ball algorithm. These steps are then extended to segment the bladder volume in a slice-by-slice manner. The obtained results were compared to manual segmentation by radiation oncologists. The average values of sensitivity,specificity,positive predictive value,negative predictive value,and Hausdorff distance are 86.5%,96.3%,90.5%,96.5%,and 2.8 pixels,respectively. The results show that the bladder can be accurately segmented.

关键词： image segmentation Computerized tomography （CT） Mean shift Bladder Rolling ball

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Technique Based on image Pyramid and Bayes Rule for Noise Reduction in Unsupervised Change Detection

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Journal of Shanghai Jiaotong university(Science) 2009年第6期14卷 659-663页

作者：李志强霍宏方涛朱巨莲葛卫丽 Institute of Image Processing and Pattern Recognition Shanghai Jiaotong University Staff Room of Command Automatization Engineering College of Armed Police Force

In this paper,a technique based on image pyramid and Bayes rule for reducing noise effects in unsupervised change detection is *** using Gaussian pyramid to process two multitemporal images respectively,two image pyramids are *** difference pyramid images are obtained by point-by-point subtraction between the same level images of the two image *** resizing all difference pyramid images to the size of the original multitemporal image and then making product operator among them,a map being similar to the difference image is *** difference image is generated by point-by-point subtraction between the two multitemporal images *** last,the Bayes rule is used to distinguish the changed *** synthetic and real data sets are used to evaluate the performance of the proposed *** results show that the map from the proposed technique is more robust to noise than the difference image.

关键词： change detection change vector analysis multitemporal images image pyramid

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A curve-fitting method for correcting radial distortion

A curve-fitting method for correcting radial distortion

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2009 2nd International Congress on image and Signal processing, CISP'09

作者： Wenjuan, Ma Yuncai, Liu Image Processing and Pattern Recognition Institute Shanghai Jiao Tong University Shanghai China

ISBN: (纸本)9781424441310

This paper presents a new method for correcting radial distortion. It makes use of a model plane including 3D lines and originally demonstrates that the distorted image of a 3D line is a circular arc. After obtained the circle equation, the distortion parameter and the supposed undistorted image are computed simultaneously. Then the camera model is equivalent to ideal pinhole camera and can be calibrated using conventional plane-based calibration algorithm. This paper successfully decouples the estimation of the radial distortion from the estimation of other camera intrinsic parameters. Experimental results verify the correctness and robustness of our method. ©2009 IEEE.

关键词： Pinhole cameras

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High-speed video transfer and real-time infrared spots detection based on FPGA

High-speed video transfer and real-time infrared spots detec...

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2nd International Workshop on Computer Science and Engineering, WCSE 2009

作者： Huang, Maoxiang Wang, Chenhao Liu, Yuncai Institute of Image Processing and Pattern Recognition Shanghai Jiao Tong University Shanghai China

ISBN: (纸本)9780769538815

This paper presents a high-speed video transfer scheme and a real-time infrared spots detection algorithm designed for Field Programmable Gate Array (FPGA) implementation. Rather than IEEE 1394a, two IEEE 1394b interfaces are alternatively used to ensure high-resolution image transfer in real time. In order to execute fast infrared spots detection, a parallel algorithm that processes four pixels per clock cycle is proposed. It detects infrared spots in a single pass over a frame and its implementation is only composed of combinatorial logic and registers. Furthermore, the execution time of the algorithm is independent of image content. A prototype system is implemented in an FPGA device. It is capable of transferring 1024 x 768 images smoothly at 60 fps and detecting infrared sports in a 1024 x 768 image within 1.966ms, demonstrating its superiority over the existing multi-pass algorithms and some other one-pass algorithms. Details of software and hardware architecture are discussed in this paper. © 2009 IEEE.

关键词： High speed cameras

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Deformable surface 3D tracking using linear programming

Deformable surface 3D tracking using linear programming

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2nd International Workshop on Computer Science and Engineering, WCSE 2009

作者： Wang, Chenhao Shen, Shuhan Liu, Yuncai Institute of Image Processing and Pattern Recognition Shanghai Jiao Tong University Shanghai China

ISBN: (纸本)9780769538815

A method for 3D shape reconstruction of deformable surfaces from consecutive frames was presented. In our method, the model of the surface is represented by a triangulated mesh. The constraints for the model, including keypoint correspondences and disallowing large changes of edge orientation between consecutive frames, are formulated as Linear Programming (LP) constraints. Therefore the deformable surface 3D tracking method turns into an LP problem that can be effectively solved. The robustness and efficiency of our approach are validated on synthetic and real data. © 2009 IEEE.

关键词： Linear programming

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Implementation of penalized-likelihood statistical reconstruction for polychromatic dual-energy CT

Implementation of penalized-likelihood statistical reconstru...

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Medical Imaging 2009: Physics of Medical Imaging

作者： Xu, Qiong Mou, Xuanqin Tang, Shaojie Wei, Hong Yizhai, Zhang Luo, Tao Institute of Image processing and Pattern recognition Xi'an Jiaotong University Xi'an Shaanxi 710049 China

ISBN: (纸本)9780819475091

This paper presents a statistical reconstruction algorithm for dual-energy (DE) CT of polychromatic x-ray source. Each pixel in the imaged object is assumed to be composed of two basis materials (i.e., bone and soft tissue) and a penalizedlikelihood objective function is developed to determine the densities of the two basis materials. Two penalty terms are used respectively to penalize the bone density difference and the soft tissue density difference in neighboring pixels. A gradient ascent algorithm for monochromatic objective function is modified to maximize the polychromatic penalizedlikelihood objective function using the convexity technique. In order to reduce computation consumption, the denominator of the update step is pre-calculated with reasonable approximation replacements. Ordered-subsets method is applied to speed up the iteration. Computer simulation is implemented to evaluate the penalized-likelihood algorithm. The results indicate that this statistical method yields the best quality.©2009 SPIE.

关键词： Pixels

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L2 approximation for efficient deformable surface 3D tracking

L2 approximation for efficient deformable surface 3D trackin...

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2009 IEEE International Conference on image processing, ICIP 2009

作者： Shen, Shuhan Shi, Wenhuan Liu, Yuncai Institute of Image Processing and Pattern Recognition Shanghai Jiao Tong University Shanghai 200240 China

ISBN: (纸本)9781424456543

We present a method for recovering 3D shapes of deformable surfaces from monocular image sequences. State-of-the-art methods on this problem [1] utilize L∞-norm of reprojection residual vectors and formulate the tracking problem as a Second Order Cone Programming (SOCP) problem. Instead of using L∞ which is sensitive to outliers, we use L 2-norm of reprojection errors. Generally, using L2 leads a non-convex optimization problem which is difficult to minimize. Instead of solving the non-convex problem directly, we approximate the non-convex objective function by a convex one in the tracking context. Then tracking is achieved by minimizing the corresponding convex problem which can be efficiently solved. The robustness and accuracy of our approach are evaluated quantitatively on synthetic data and qualitatively on real data. ©2009 IEEE.

关键词： Second-order cone programming

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