Three-dimensional finite-element code for electrosurgery and thermal ablation simulations

• US 20060257836A1
• Filed: 12/21/2005
• Published: 11/16/2006
• Est. Priority Date: 12/23/2004
• Status: Active Grant

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Covidien AG (Medtronic Plc)
• Inventors: Rick, Kyle R., Schechter, David A., Goldberg, Nahum, Humphries, Stanley
• Granted Patent: US 7,467,075 B2
• Time in Patent Office: Days
• US Class Current: 434/262
• CPC Class Codes: G09B 23/30 Anatomical models G09B23/281 - G09B23/288 take precedence

Abstract

A system and method for performing a simulation of an electrosurgical procedure are disclosed. The method includes the steps of generating a three-dimensional medium, which includes one or more material regions representing a physical object. The method also includes the steps of dividing the medium into multiple hexahedron elements to generate a three-dimensional conformal mesh and assigning each element to the material region. The method further includes the steps of calculating an electrical energy solution and a thermal transport solution and generating graphical representations illustrating one or more aspects of the electrical energy and the thermal transport solutions.

Claims

1. A method for performing a simulation of an electrosurgical procedure, the method comprising the steps of:

generating a three-dimensional medium comprising at least one material region representing a physical object;

dividing the medium into a plurality of hexahedron elements to generate a three-dimensional conformal mesh;

assigning each element to a corresponding at least one material region;

calculating at least one of an electrical energy solution and a thermal transport solution; and

generating at least one of a graphical representation representing at least one aspect of the electrical energy solution and one aspect of the thermal transport solution.

2. A method as in claim 1, wherein the step of calculating the electrical energy solution further comprises a step of solving equations 1 and 2

$\begin{array}{c}\nabla \end{array}$

·

[ ( ɛ

r - jσ

ɛ

0 ⁢

ω

) ⁢

∇

ϕ

] = 0 ( 1 ) E = - ∇

ϕ

( 2 )

wherein ε

_r is a relative dielectric constant and σ

is electrical conductivity of each the elements and E is amplitude and phase of electric field.

3. A method as in claim 2, wherein the step of calculating the thermal transport solution further comprising a step of solving equations 3 and 4:

$\begin{array}{cc}{q}_e=\mathrm{\sigma <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>E·<br><br>E*/2& \left(3\right)\\ \mathrm{\rho <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>C_p<br><br>\frac{\partial <br><br>T}{\partial <br><br>t}=\nabla <br><br>·<br><br>\left(k<br><br>\nabla <br><br>T\right)+q_e+q_m+W_b<br><br>\left(T_b-T\right)& \left(4\right)\end{array}$

wherein ρ

is density of the medium, C_ρ

is specific heat, k is thermal conductivity, q_m is heat generated by metabolism, and W_b(T_b−

T) represents thermal variations caused by blood flow.

4. A method as in claim 1, wherein the material region includes a material state, the material state comprising at least one physical property.

5. A method as in claim 4, wherein the at least one physical property is selected from the group consisting of relative dielectric constant, electrical conductivity, specific heat, thermal conductivity, and blood flow.

6. A method as in claim 5, wherein the at least one physical property is temperature-dependent.

7. A method as in claim 6, wherein a tabular function stores a plurality of temperature-dependent variables for the at least one physical property.

8. A method as in claim 6, further comprising the step of:

updating the electrical energy solution and the thermal transport solution as a function of the at least one temperature-dependent physical property.

9. A method as in claim 1, wherein the plurality of elements are ordered in the three-dimensional mesh according to cubic logic.

10. A method as in claim 1, wherein the graphical representation is a three-dimensional plot and the at least one aspect of the thermal solution is an isothermal surface of the medium.

11. A method as in claim 1, wherein the graphical representation is a two dimensional slice plot and the at least one aspect of the electrical solution is electrical conductivity of the medium.

12. A system for performing a simulation of an electrosurgical procedure, the system comprising:

a processor configured to generate a three-dimensional medium having at least one material region representing a physical object and dividing the medium into a plurality of hexahedron elements to generate a three-dimensional conformal mesh, the processor further configured to assign each element to a corresponding at least one material region and calculate at least one of an electrical energy solution and a thermal transport solution; and

an output device which outputs at least one of a graphical representation representing at least one aspect of the electrical energy solution and one aspect of the thermal transport solution.

13. A system as in claim 12, wherein the material region includes a material state, the material state comprising at least one physical property.

14. A system as in claim 13, wherein the at least one physical property is selected from the group consisting of relative dielectric constant, electrical conductivity, specific heat, thermal conductivity, and blood flow.

15. A system as in claim 14, wherein the at least one physical property is temperature-dependent.

16. A system as in claim 15 wherein a tabular function stores a plurality of temperature-dependent variables for the at least one physical property.

17. A system as in claim 16, wherein:

electrical energy solution and the thermal transport solution is updated as a function of the at least one temperature-dependent physical property.

18. A system as in claim 12, wherein the plurality of elements are ordered in the three-dimensional mesh according to cubic logic.

19. A system as in claim 12, wherein the graphical representation is a three-dimensional plot and the at least one aspect of the thermal solution is an isothermal surface of the medium.

20. A system as in claim 12, wherein the graphical representation is a two dimensional slice plot and the at least one aspect of the electrical solution is electrical conductivity of the medium.

21. A set of computer-executable instructions for performing a simulation of an electrosurgical procedure, the computer-executable instructions comprising the steps of:

generating a three-dimensional medium having at least one material region representing a physical object;

dividing the medium into a plurality of hexahedron elements to generate a three-dimensional conformal mesh;

assigning each element to a corresponding at least one material region;

calculating an electrical energy solution and a thermal transport solution for a predetermined period of time; and

generating at least one of a graphical representation representing at least one aspect of the electrical energy solution and one aspect of the thermal transport solution.