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Advanced Soft-Tissue Simulation for Medical Procedures

Explore the simulation of intestines, fallopian tubes, muscles, and surgical tools for advanced medical training and research. Learn about dynamic modeling, physical constraints, and interactive behaviors in this cutting-edge simulation technology.

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Advanced Soft-Tissue Simulation for Medical Procedures

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  1. Julien Lenoir IPAM January 11th, 2008 1D models in medical simulation

  2. Classification • Human tissues: • Intestines • Fallopian tubes • Muscles • … • Tools: • Surgical thread • Catheter, Guide wire • Coil • …

  3. Soft-Tissue Simulation 1. Intestines simulation

  4. Intestines simulation [FLMC02] • Goal: • Clear the operation field prior to a laparoscopic intervention • Key points: • Not the main focus of the intervention • High level of interaction with user

  5. Intestines simulation [FLMC02] Real intestines characteristics: • Small intestines (6 m/20 feet) &Large intestines or colon (1.5 m/5 feet) • Huge viscosity (no friction needed) • Heterogeneous radius (some bulges) • Numerous self contact Simulated intestines characteristics: • Needed: • Dynamic model with high resolution rate for interactivity • High viscosity (no friction) • Not needed: • Torsion (no control due to high viscosity)

  6. Intestines simulation [FLMC02] • Physical modeling: dynamic spline model • Previous work • [Qin & Terzopoulos TVCG96] “D-NURBS” • [Rémion et al. WSCG99-00] • Lagrangian equations applied to a geometric spline: Basis spline function (C1, C2…) DOFs = Control points position Kinetic and potential energies • Similar to an 1D FEM using an high order interpolation function (the basis spline functions)

  7. Intestines simulation [FLMC02] • Physical modeling: dynamic spline model • Using cubic B-spline (C2 continuity) • Complexity O(n) due to local property of spline • 3D DOF => no torsion ! • Potential energies (deformations) = springs Stretching Bending

  8. Intestines simulation [FLMC02] • Collision and Self-collision model: • Sphere based • Broad phase via a voxel grid • Dynamic distribution (curvilinear distance) Extremity of a spline segment

  9. Intestines simulation [FLMC02] • Dynamic model: • Explicit numerical integration (Runge-Kutta 4) • 165 control points • 72 Hz (14ms computationtime for 1ms virtual) • Rendering usingconvolution surface or implicit surface

  10. Soft-Tissue Simulation 2. Fallopian tubes

  11. Fallopian tubes • Avoid intrauterine pregnancy • Simulation of salpingectomy • Ablation of part/all fallopian tube • Clamp the local area • Cut the tissue • Minimally Invasive Surgery (MIS)

  12. Fallopian tubes • Choice of a predefine cut (not a dynamic cut): • 3 dynamic splines connected to keep the continuity Constraints insuring C2 continuity 3 dynamic spline models • Release appropriate constraints to cut

  13. Fallopian tubes • Physical modeling: • Dynamic spline model • Constraints handled with Lagrange multipliers + Baumgarte scheme: • 3 for each position/tangential/curvature constraint => 9 constraints per junction • Fast resolution using a acceleration decomposition:

  14. Fallopian tubes • Collision and Self-collision with spheres

  15. Soft-Tissue Simulation 3. Muscles

  16. Muscles • Dinesh Pai’s work • Musculoskeletal strand • Based on Strands [Pai02] • Cosserat formulation • 1D model for muscles • Joey Teran’s work • FVM model [Teran et al., SCA03] • Invertible element [Irving et al., SCA04] • Volumetric model for muscles (3D)

  17. Tool Simulation 4. Surgical Thread Simulation

  18. Surgical Thread Simulation • Complex and complete behavior • Stretching • Bending • Torsion • Twist control very important for surgeons • Highly deformable & stiff behavior • Highly interactive • Suturing, knot tying…

  19. Surgical Thread Simulation • Dynamic spline • Continuous deformations energies • Continuous stretching [Nocent et al. CAS01] • Green/Lagrange strain tensor (deformation) • Piola Kircchoff stress tensor (force) • Continuous bending (approx. using parametric curvature) • No Torsion • [Theetten et al. JCAD07] 4D dynamic spline with full continuous deformations

  20. Surgical Thread SimulationHelpful tool for Suturing • A new type of constraint for suturing: • Sliding constraint:Allow a 1D model to slide through a specific point (tangent, curvature…can also be controlled) Usual fixed point constraint Sliding point constraint

  21. Surgical Thread SimulationHelpful tool for Suturing • s becomes a new unknown: a free variable • Requires a new equation: • Given by the Lagrange multiplier formalism = Force ensuring the constraint g P(s,t) s(t)

  22. Surgical Thread SimulationHelpful tool for Suturing • Resolution acceleration: • by giving a direct relation to compute P(s,t) s(t)

  23. Surgical Thread SimulationHelpful tool for Suturing

  24. Surgical Thread SimulationHelpful tool for knot tying • Lack of DOF in the knot area:

  25. insertion Surgical Thread SimulationHelpful tool for knot tying • Adaptive resolution of the geometry: • Exact insertion algorithm (Oslo algorithm): NUBS of degree d Knot vectors: • Simplification is often an approximation

  26. Surgical Thread SimulationHelpful tool for knot tying • Results: Non adaptive dynamic spline Adaptive dynamic spline

  27. Surgical Thread SimulationHelpful tool for cutting • Useful side effect of the adaptive NUBS: • Multiple insertion at the same parametric abscissa decreases the local continuity • Local C-1 continuity => cut

  28. Tool Simulation 5. Catheter/Guidewire navigation

  29. Catheter/Guidewire navigation • Interventional neuroradiology • Diagnostic: • Catheter/Guidewirenavigation • Therapeutic: • Coil • Stent • …

  30. Catheter/Guidewire navigation • Arteries/venous network reconstruction • Patient specific datafrom CT scan or MRI • Vincent Luboz’swork at CIMIT/MGH

  31. Catheter/Guidewire navigation • Physical modeling of Catheter/Guidewire/Coil: • 1 mixed deformable object => • Adaptive mechanical properties • Adaptive rest position • Beam element model (~100 nodes) • Non linear model (Co-rotational) • Static resolution:K(U).U=F1 Newton iteration = linearization • Arteries are not simulated (fixed or animated)

  32. Catheter/Guidewire navigation • Contact handling: • Mechanics of contact: Signorini’s law • Fixed compliance C during 1 time step=> Delassus operator: • Solving the current contact configuration: • Detection collision • Loop until no new contact • Use status method to eliminate contacts • Detection collision • If algorithm diverge, use sub-stepping

  33. Catheter/Guidewire navigation • Arteries 1st test: • Triangulated surface for contact

  34. Catheter/Guidewire navigation • Arteries 2nd test: • Convolution surface forcontact f(x)=0 • Based on a skeletonwhich can be animatedvery easily and quickly • Collision detectionachieve by evaluatingf(x) • Collision responsealong f(x)

  35. Catheter/Guidewire navigation

  36. Catheter/Guidewire navigation • Coil deployment: • Using the same technique

  37. Others 1D model 6. Hair simulation

  38. Hair simulation • Florence Bertail’s (PhD06 – SIGGRAPH07) • L’Oréal

  39. Hair simulation • Dynamic model • Animated with Lagrange equations • Kircchoff constitutive law • Physical DOF (curvatures + torsion) • Easy to evaluate the deformations energies • Difficult to reconstruct the geometry:Super-Helices [Bertails et al., SIGGRAPH06]

  40. The END

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