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ENDOSCOPIC IMAGE CUTTING SIMULATION BASED ON mass-spring model AND COMPUTATIONAL GEOMETRY

JOURNAL OF CIRCUITS SYSTEMS AND COMPUTERS 2009年第8期18卷 1453-1465页

作者： Yuan, Zhiyong Feng, Shikun Yin, Qian Wang, Xiali Zhang, Dengyi Zhao, Jianhui Chen, Mianyun Wuhan Univ Sch Comp Sci Wuhan 430072 Hubei Peoples R China Beijing Normal Univ Coll Informat Sci & Technol Beijing 100875 Peoples R China Huazhong Univ Sci & Technol Dept Control Sci & Engn Wuhan 430074 Hubei Peoples R China

As minimally invasive surgical techniques become widely known to patients, medical training systems based on virtual simulation are highly desired. These systems help surgeon trainees to acquire, practice and evaluate their surgical skills. A key component in a virtual training system is to simulate the dynamics that occur in surgical procedures. Tissue cutting, as a common phenomenon during surgery, has attracted many research efforts in computer simulation. In this paper, we propose an approach to endoscopic image cutting simulation which is based on both mass-spring model and Computational Geometry. In the cutting simulation model, the springs to be cut off are imagined into line segments. In the calculation of the elastic force on mass points, we have found that whether some adjacent springs of a mass point to be eliminated or not during a cutting is critical. If a spring intersects the cutting plane, we set the elastic force of this spring to zero. We adopted properties of cross product and related algorithms (the rapid exclusion test, the crossover test) in Computational Geometry to determine the springs that are intersected with the cutting plane. And then, we utilized the bilinear interpolation and OpenGL techniques to render the cutting procedure of the soft tissue. The experimental results show that our cutting simulation is effective and practical.

关键词： Cutting simulation mass-spring model cross product cutting plane

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Modified mechanical mass-spring model of biomolecules for understanding dynamics of proteins

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JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2008年第3期22卷 506-513页

作者： Eom, Kilho Ahn, Jeong-Hee Kim, Jae-In Yoon, Gwon-Chan Na, Sungsoo Korea Univ Dept Mech Engn Seoul 136713 South Korea Korea Inst Sci & Technol Microsyst Res Ctr Seoul 136791 South Korea

A dynamic model applicable to biomolecular structures for understanding the dynamics and the vibrational behaviors of protein is considered. A mechanical mass-spring model represented by point masses and harmonic springs is presented. The biomolecular structure may be envisioned by a mass and spring system with multi-degrees-of-freedom because dominant atoms in protein may be considered to be point masses, and bonding and non-bonding interactions between atoms of interest and surrounding atoms within some critical distances are implemented by a spring. Furthermore, a model condensation scheme is to be introduced because most proteins have large degree of freedom requiring large computation time and memory, which results in reducing computational cost and maintaining the accurate predictions. From solving the corresponding eigenvalue problem constructed from a multi-degree-of-freedom system, our results show the modified mechanical spring-mass model of a biostructure through a condensation scheme is very successful in predicting the dynamics of molecular structures in terms of thermal fluctuations and eigenmode, etc.

关键词： mass-spring model biomolecular structure multi-degree-of-freedom system eigenvalue problem model condensation

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Image-based mass-spring model of mitral valve closure for surgical planning

Image-based mass-spring model of mitral valve closure for su...

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Medical Imaging 2008 Conference

作者： Hammer, Peter E. Perrin, Douglas P. del Nido, Pedro J. Howe, Robert D. Tufts Univ Dept Biomed Engn Medford MA 02155 USA Childrens Hosp Depat Cardiac Surg Boston MA USA Harvard Univ Sch Engn Appl Sci Cambridge MA 02138 USA

ISBN: (纸本)9780819471024

Surgical repair of the mitral valve is preferred in most cases over valve replacement, but replacement is often performed instead due to the technical difficulty of repair. A surgical planning system based on patient-specific medical images that allows surgeons to simulate and compare potential repair strategies could greatly improve surgical outcomes. In such a surgical simulator, the mathematical model of mechanics used to close the valve must be able to compute the closed state quickly and to handle the complex boundary conditions imposed by the chords that tether the valve leaflets. We have developed a system for generating a triangulated mesh of the valve surface from volumetric image data of the opened valve. We then compute the closed position of the mesh using a mass-spring model of dynamics. The triangulated mesh is produced by fitting an isosurface to the volumetric image data, and boundary conditions, including the valve annulus and chord endpoints, are identified in the image data using a graphical user interface. In the mass-spring model, triangle sides are treated as linear springs, and sides shared by two triangles are treated as bending springs. Chords are treated as nonlinear springs, and self-collisions are detected and resolved. Equations of motion are solved using implicit numerical integration. Accuracy was assessed by comparison of model results with an image of the same valve taken in the closed state. The model exhibited rapid valve closure and was able to reproduce important features of the closed valve.

关键词： mitral valve mass-spring model simulation

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A Real-Time Stable Volumetric mass-spring model Based on a Multi-Scale Mesh Representation An Application to Medical Virtual Reality 23

A Real-Time Stable Volumetric Mass-Spring Model Based on a M...

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23rd Iranian Conference on Biomedical Engineering / 1st International Iranian Conference on Biomedical Engineering (ICBME)

作者： Farhang, Sepide Foruzan, Amir Hossein Chen, Yen-Wei Shahed Univ Biomed Engn Dept Fac Engn Tehran Iran Ritsumeikan Univ Coll Informat Sci & Engn Intelligent Image Proc Lab Kyoto Japan

ISBN: (纸本)9781509034529

Representation of soft tissues in virtual reality environments has been focused by researchers with applications including training medical students and surgeons, treatment planning, monitoring and telesurgery. A major challenge of current modeling schemes such as Boundary Element, Finite Element, and mass-spring models is to deal with volume preserving. Another challenge is the complexity of a model which results in a more realistic visualization;however, it increases computational cost. In this paper, we propose a mass-spring model to represent liver volume. It contains a series of multi-scale surface meshes with interconnections between the models and therefore it is considered as a volumetric mesh model. To preserve the volume of the gland, an external force is transmitted from the surface to internal meshes. By designing a specific data structure to hold coordinates of mesh points, we are able to render mesh movement in nearly real-time using conventional CPU architectures. Localization of the external force is adjusted by the penetration depth parameter. Qualitative evaluation of the results revealed the promising performance of the proposed model. The stability of our mass-spring model under large deformation is another novelty of our method too.

关键词： Medical virtual reality mass-spring model Liver surgical simulator volumetric mesh Multi-scale mesh model

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A Deformation Method in a Wrapping Manner for Virtual Gingiva Based on mass-spring model 18

A Deformation Method in a Wrapping Manner for Virtual Gingiv...

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International Normal Labour and Birth Research Conference

作者： Ma, Tian Li, Yun Li, Jiaojiao Li, Yuancheng Xian Univ Sci & Technol Coll Comp Sci & Technol Xian Peoples R China

ISBN: (纸本)9781728147659

In order to solve the problem that the boundary of gingiva is wrinkled after deformation in orthodontic simulation, we designed a simulation method in a wrapping manner for virtual gingiva based on the traditional mass-spring model. Firstly, the transition boundary point between teeth and gums was selected as the active point in the deformation process, and the position of the active point was determined by wrapping it on the tooth surface after the correction operation. Then, in order to solve the problem of missing attachment point when the position of the active point is determined, we added a segment of tooth root based on the method of tooth contour curve fitting. Finally, we used the sum of surface curvature values to compare the experimental results. The experimental results show that the proposed method can effectively alleviate the problem of boundary wrinkles after gingival deformation in the case of large correction range, and improve the authenticity of the virtual orthodontic system.

关键词： virtual orthodontics soft tissue deformation mass-spring model wrapping deformation virtual orthodontics soft tissue deformation mass-spring model wrapping deformation

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A mass-spring model for haptic display of flexible object global deformation

A mass-spring model for haptic display of flexible object gl...

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IEEE International Conference on Mechatronics and Automation

作者： Tong, Cui Song, Aiguo Juan, Wu SE Univ Dept Instrument Sci & Engn Nanjing 210096 Peoples R China

ISBN: (纸本)9781424408276

The global deformation model of virtual object by force is a key issue for haptic interaction between human and virtual reality. A discrete globe mass - spring model is proposed for flexible object deformation, and its surface is divided radially along the force center. The mass-spring system is composed of the nodes connected with radial distributed springs. Using the theory of virtual work, the relations between virtual force and nodal displacements are analyzed to get global deformations. Object globe deformation is simulated by measuring the nodal deformations based on a force equation at each node. According to the model, the deformation of the flexible object is simulated, and synchronously the real-time virtual contact force is provided with delta haptic device.

关键词： mass-spring model virtual reality haptic feedback

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Simulation of soft tissue using mass-spring model with simulated annealing optimization

Simulation of soft tissue using mass-spring model with simul...

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IEEE International Conference on Automation and Logistics

作者： Xu, Shaoping Liu, Xiaoping Zhang, Hua Nanchang Univ Sch Informat Engn Nanchang 330031 Peoples R China Nanchang Univ Sch Mechatron Engn Nanchang 330031 Jiangxi Peoples R China

ISBN: (纸本)9781424447947

A key challenge of the simulation of deformable soft tissue is to satisfy the conflicting requirements of real-time interactivity and physical realism. The behavior of soft tissue can be described by a mass-spring model provided that correct parameters, such as spring stiffness and viscosity, are used. In practice, such parameters are often determined by trial-and-error based on the visual effects of simulation. Therefore, it is very difficult to obtain accurate values, and the process is tedious and time consuming. In this paper, a heuristic optimization technique is proposed to identify these parameters of the mass-spring model for soft tissue simulation. We employ the simulated annealing algorithm to tune the parameters automatically until the deformation of simulated soft tissue approximates the reference one as defined by a new modified tensor-mass model in which we have taken into account the viscoelasticity of soft tissue. The proposed technique provides an automatic method to determine the parameters in mass-spring-based models.

关键词： Simulation of soft tissue mass-spring model tensor-mass model heuristic optimization

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Realization and Application of mass-spring model in Haptic Rendering System for Virtual Reality

Realization and Application of Mass-Spring Model in Haptic R...

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2nd International Conference on Intelligent Computation Technology and Automation

作者： Wang, Huiying Wang, Yu Esen, Hasan Tongji Univ Chinese German Sch Appl Sci Shanghai 200092 Peoples R China Tech Univ Munich Dept Elect Engn & Informat Technol D-80333 Munich Germany

ISBN: (纸本)9780769538044

Deformable objects raise a complex combination of issues ranging from estimating mechanical parameters, solving large systems of differential equations, detecting collisions, modeling responses to collisions. Some issues in surgical simulation such as collision detection and feedback force computation still lack adequate solutions. To resolve these problems, we researched on the haptic rendering system for virtual reality and optimized the mass-spring model of deformable objects for surgical simulation. This paper introduces mass-spring model for deformable objects and the composition and applications of a haptic rendering system for virtual reality. The mass-spring models of human organs have been integrated into a haptic rendering system for virtual reality for surgical simulation. Based on the simulation results, the performances and the application prospects of the mass-spring model are analysed and discussed as conclusions.

关键词： deformable objects real-time simulation mass-spring model haptic rendering virtual reality

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Real-time vascular beating analog based on the mass-spring model

Real-time vascular beating analog based on the mass-spring m...

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9th International Conference on Intelligent Information Hiding and Multimedia Signal Processing (IIH-MSP)

作者： Zhi, Xin Zhang, Ziming Gao, Yuhui Zhang, Zhixiang Beijing Univ Technol Coll Elect Informat & Control Engn Beijing Peoples R China

ISBN: (纸本)9780769551203

Virtual vascular interventional operation is a virtual reality technology application in medical training. In this paper, we propose a real-time approach to vascular beating modeling, which can be used in virtual interventional simulation system. First of all, we read out the VTK file of vascular model through VTK function. Then, we choose a center point in a small space and structure the mass-spring model between the center point and other points discreted on the vascular model. After that, we give the center point a force to pull other points. Finally, we set a time callback function to give a beating frequency. Thus, the vascular will beat according to human heart beating rate. Our experimental results show that the method is simple and effective, it can also provide a visually plausible vascular beating effect in a realtime way. So it can become an important part of virtual interventional simulation system.

关键词： mass-spring model interventional surgery realtime-simulation VTK

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Evaluation of Image Registration using a mass-spring model of the Breast

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11th International Congress of the IUPESM/World Congress on Medical Physics and Biomedical Engineering

作者： Boehler, T. Peitgen, H. -O. Inst Med Image Comp Fraunhofer MEVIS Bremen Germany

ISBN: (纸本)9783642038815

Deformable motion correction has become a fundamental image processing task for the quantitative analysis of dynamic contrast-enhanced breast magnetic-resonance imaging (MRI). However, although various non-linear image registration techniques are available, objective evaluation remains challenging. In this paper, we propose a biomechanical model of the breast based on a mass-spring system and an internal tetrahedron structure. We demonstrate how this model can be applied to clinical datasets to generate plausible breast deformations for the evaluation. For this purpose, we integrate a thin-plate spline image transformation into the model. Furthermore, we show how the specific model can be used to quantitatively evaluate breast MRI motion correction, and present preliminary registration results achieved with the proposed method.

关键词： image registration motion correction breast MRI breast model mass-spring model

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