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23
A Hybrid Elastic Model allowing RealTime Cutting, Deformations and ForceFeedback for Surgery Training and Simulation
, 2000
"... We propose three different physical models based on linear elasticity theory and finite elements modeling that are wellsuited for surgery simulation. The first model combines pre computed deformations to deform in realtime large size meshes but does not allow any topo logical changes to the mes ..."
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Cited by 105 (20 self)
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We propose three different physical models based on linear elasticity theory and finite elements modeling that are wellsuited for surgery simulation. The first model combines pre computed deformations to deform in realtime large size meshes but does not allow any topo logical changes to the mesh. The second model is similar to the springmass models where volumetric deformations and cutting operations can be simulated on small size meshes in real time. Finally, we have developpeal a third method combining the previous two solutions into a hybrid model thus allowing the simulation of deformations and cutting on complex anatomical structures.
Towards realistic soft tissue modeling in medical simulation
 Proceedings of the IEEE
, 1998
"... Most of today's medical simulation systems are based on geometric representations of anatomical structures that take no account of their physical nature. Representing physical phenomena and, more speci cally the realistic modeling of soft tissue will not only improve current medical simulation ..."
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Cited by 87 (3 self)
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Most of today's medical simulation systems are based on geometric representations of anatomical structures that take no account of their physical nature. Representing physical phenomena and, more speci cally the realistic modeling of soft tissue will not only improve current medical simulation systems but will considerably enlarge the set of applications and the credibility of medical simulation, from neurosurgery planning to laparoscopic surgery simulation. In order to achieve realistic tissue deformation, it is necessary to combine deformation accuracy with computer e ciency. On the one hand, biomechanics has studied complex mathematical models and produced a large amount of experimental data for representing the deformation of soft tissue. On the other hand, computer graphics has proposed many algorithms for the realtime computation of deformable bodies, often at the cost of ignoring the physics principles. In this paper, we survey existing models of deformation in medical simulation and we analyze the impediments to combining computergraphics representations with biomechanical models. In particular, the di erent geometric representations of deformable tissue are compared in relation to the tasks of realtime deformation, tissue cutting and forcefeedback interaction. Finally, we inspect the potential of medical simulation under the development ofthiskey technology. 1
Haptic Subdivision: an Approach to Defining Levelofdetail in Haptic Rendering
, 2002
"... Soft objects are often desired in applications such as virtual surgery training. Soft object simulations are computationally intensive because object deformation involves numerically solving a large number of differential equations. However, realistic force feedback requires deformation be computed ..."
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Cited by 13 (1 self)
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Soft objects are often desired in applications such as virtual surgery training. Soft object simulations are computationally intensive because object deformation involves numerically solving a large number of differential equations. However, realistic force feedback requires deformation be computed fast and graphic feedback requires deformation be highly detailed. In this paper, we propose an approach that balances these requirements by subdividing the area of interest on a relatively coarse mesh model. Thus we keep the number of nodes of the model under control so that the simulation can be run at a sufficiently high rate for force feedback. The model we use is based on a massspring model. When a portion of the surface is subdivided, new values of mass and spring constants are determined such that computed force feedback offers the user the same reaction force as before subdivision.
A Layered Model of a Virtual Human Intestine for Surgery Simulation
, 2004
"... In this paper, we propose a new approach to simulate the small intestine in a context of laparoscopic surgery. The ultimate aim of this work is to simulate the training of a basic surgical gesture in realtime: moving aside the intestine to reach hidden areas of the abdomen. The main problem posed b ..."
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Cited by 11 (0 self)
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In this paper, we propose a new approach to simulate the small intestine in a context of laparoscopic surgery. The ultimate aim of this work is to simulate the training of a basic surgical gesture in realtime: moving aside the intestine to reach hidden areas of the abdomen. The main problem posed by this kind of simulation is animating the intestine. The problem comes from the nature of the intestine: a very long tube which is not isotropically elastic, and is contained in a volume that is small when compared to the intestine's length. It coils extensively and collides with itself in many places.
Modeling simulation and planning of needle motion in soft tissues
, 2003
"... Precise needle placement is required for the success of a wide variety of percutaneous interventions in medicine. Insertions into soft tissues can be difficult to learn and to perform, due to tissue deformation, needle deflection and limited visual feedback. Little quantitative information is known ..."
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Cited by 6 (0 self)
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Precise needle placement is required for the success of a wide variety of percutaneous interventions in medicine. Insertions into soft tissues can be difficult to learn and to perform, due to tissue deformation, needle deflection and limited visual feedback. Little quantitative information is known about the interaction between needles and soft tissues during puncture, and no effective physicallybased training, planning and guidance systems exist for such procedures. This work aims to characterise needletissue interaction by measuring contact forces and deformations that are applied during insertions into soft tissue phantoms. A new methodology for estimating the forces that occur along the needle shaft during insertion is described. The approach is based on physical experiments, as well as on linear elastic phantom models that are discretised by traditional Finite Element Methods. Shaft force distributions are derived from insertions into homogeneous and simple layered inhomogeneous tissue phantoms at several driving velocities, and are applied as boundary conditions to tissue models for physicallybased simulations of needle insertion trajectories. A largestrain elastic needle model is coupled to the tissue models to account for needle deflection and bending during simulated insertion. Since
Simulation of Deformable Organs with a Hybrid Approach
, 2001
"... In this paper, we describe two complementary methodologies for the reconstruction and animation of volumetric deformable objects from planar contours. The reconstruction is based on two different modelling techniques: implicit surfaces and particle systems. Although the implicit surfaces allow to ea ..."
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Cited by 3 (1 self)
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In this paper, we describe two complementary methodologies for the reconstruction and animation of volumetric deformable objects from planar contours. The reconstruction is based on two different modelling techniques: implicit surfaces and particle systems. Although the implicit surfaces allow to easily model complex shapes, their deformation is troublesome. On the contrary, the reconstruction process based on particle systems requires an important computation time. Nevertheless, they permit to model different behaviours from rigid to fluid state. In the scope of a medical application, we want to simulate the motion and the form alteration of the internal anatomical shapes. An acceptable computation time with realistic simulation results requires to use a hybrid approach: implicit surfaces for organs that admit small deformations and particle systems for those subject to large deformations. In this paper, we have introduced the necessary tools to handle the reconstruction of different organs as well as their interaction within a hybrid approach.
New MassSpring System Integrating Elasticity Parameters
"... Abstract Besides the finite element method, the massspring discrete modeling is widely used in computer graphics. This discrete model allows to perform very easily interactive deformations and to handle quite complex interactions with only a few equations. Thus, it is perfectly adapted to generate v ..."
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Cited by 3 (2 self)
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Abstract Besides the finite element method, the massspring discrete modeling is widely used in computer graphics. This discrete model allows to perform very easily interactive deformations and to handle quite complex interactions with only a few equations. Thus, it is perfectly adapted to generate visually correct animations. However, a drawback of this simple formulation is the relative difficulty to control efficiently physically realistic behaviors. Indeed, none of the existing models has succeeded to deal satisfyingly with this. Moreover, we demonstrate that the mostly cited technique in the literature, proposed by Van Gelder, is far to be exact in most real cases and its interest is limited to some specific non realistic animations. Here, we propose a new general 2D formulation that reconstructs the geometrical model as an assembly of elementary ”bricks”. Each brick (or element) is then transformed into a massspring system, in which edges are springs connecting masses placed on the element vertices. The key point of our approach is the determination of the stiffness constant of each spring to reproduce the correct mechanical properties (Young’s modulus, Poisson’s ratio and shear modulus) of the reconstructed object. We validate our methodology with the help of some numerical experimentation of mechanics, like stretching, shearing and loading and then we evaluate the accuracy limits of our approach.
F.: Integrating tensile parameters in 3d massspring system
 In: Proceedings of Surgetica (2007
"... Besides finite element method, massspring discrete modeling is widely used in computer graphics. This discrete model allows to perform very easily interactive deformations and to handle quite complex interactions with only a few equations. Thus, it is perfectly adapted to generate visually correct ..."
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Cited by 2 (0 self)
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Besides finite element method, massspring discrete modeling is widely used in computer graphics. This discrete model allows to perform very easily interactive deformations and to handle quite complex interactions with only a few equations. Thus, it is perfectly adapted to generate visually correct animations. However, a drawback of this simple formulation is the relative difficulty to control efficiently physically realistic behaviors. Indeed, none of the existing models has succeeded in dealing with this satisfyingly. Here, we propose a new general 3D formulation that reconstructs the geometrical model as an assembly of elementary "bricks". Each brick (or element) is then transformed into a massspring system. Edges are replaced by springs that connect masses representing the element vertices. The key point of our approach is the determination of the springstiffness to reproduce the correct mechanical properties (Young’s modulus, Poisson’s ratio, bulk and shear modulus) of the reconstructed object. We validate our methodology by performing some numerical experimentations, like shearing and loading, or beam deflection and then we evaluate the accuracy limits of our approach. 1.
Deformable Ob jects Modeling and Animation: Application to Organs ' Interactions Simulation
"... Abstract. In this paper we describe a methodology for the calculation and animation of volumetric deformable objects. The goal of this work is to obtain realistic models of internal organs in order to simulate their motion and their form alteration during a radiotherapy process. Thus, these models s ..."
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Cited by 1 (0 self)
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Abstract. In this paper we describe a methodology for the calculation and animation of volumetric deformable objects. The goal of this work is to obtain realistic models of internal organs in order to simulate their motion and their form alteration during a radiotherapy process. Thus, these models should be able to represent the internal movements due to rhythmic motions, respiration, filling/emptying processes and organs ' interactions. So we show how this can be done using particle systems and implicit surfaces and how to mix both models in an hybrid scene making organ's interaction simulation easier.
Integrating Tensile Parameters in Hexahedral MassSpring System for Simulation
"... Besides finite element method, massspring systems are widely used in Computer Graphics. It is indubitably the simplest and most intuitive deformable model. This discrete model allows to perform interactive deformations with ease and to handle complex interactions. Thus, it is perfectly adapted to g ..."
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Cited by 1 (0 self)
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Besides finite element method, massspring systems are widely used in Computer Graphics. It is indubitably the simplest and most intuitive deformable model. This discrete model allows to perform interactive deformations with ease and to handle complex interactions. Thus, it is perfectly adapted to generate visually plausible animations. However, a drawback of this simple formulation is the relative difficulty to control efficiently physically realistic behaviours. Indeed, none of the existing models has succeeded in dealing with this satisfyingly. We demonstrate that this restriction cannot be overpassed with the classical massspring model, and we propose a new general 3D formulation that reconstructs the geometrical model as an assembly of elementary hexahedral "bricks". Each brick (or element) is then transformed into a massspring system. Edges are replaced by springs that connect masses representing the vertices. The key point of our approach is the determination of the stiffness springs to reproduce the correct mechanical properties (Young’s modulus, Poisson’s ratio) of the reconstructed object. We validate our methodology by performing some numerical experiments. Finally, we evaluate the accuracy of our approach, by comparing our results with the deformation obtained by finite element method.