Apparatus and method for optimizing tumor treatment efficiency by electric fields

• US 20040176804A1
• Filed: 03/28/2003
• Published: 09/09/2004
• Est. Priority Date: 02/17/2000
• Status: Active Grant

• Current Assignee: Novocure GmbH (NovoCure Limited)
• Original Assignee: Standen'S Limited (Standen's Management, Inc.)
• Inventors: Palti, Yoram
• Granted Patent: US 7,146,210 B2
• Time in Patent Office: Days
• US Class Current: 607/2
• CPC Class Codes: A61N 1/0408 Use-related aspects
• CPC Class Codes: A61N 1/0484 Garment electrodes worn by the patient
• CPC Class Codes: A61N 1/0492 Patch electrodes A61N1/0412, A61N1/0428 take precedence
• CPC Class Codes: A61N 1/326 for promoting growth of cells, e.g. bone cells
• CPC Class Codes: A61N 1/36021 for treatment of pain
• CPC Class Codes: A61N 1/36071 Pain
• CPC Class Codes: A61N 1/40 Applying electric fields by inductive or capacitive coupling microwave apparatus A61N5/00; Applying radio-frequency signals

Abstract

The apparatus and method are designed to compute the optimal spatial and temporal characteristics for combating tumor growth within a body on the basis of cytological (as provided by biopsies, etc.) and anatomical data (as provided by CT, MRI, PET, etc.), as well as the electric properties of the different elements. On the basis of this computation, the apparatus applies the fields that have maximal effect on the tumor and minimal effect on all other tissues by adjusting both the field generator output characteristics and by optimal positioning of the insulated electrodes or isolects on the patient'"'"'s body.

Claims

1. A method for optimizing the selective destruction of dividing cells in a malcontrolled cell growth using a device that subjects the cell growth to an alternating electric field, wherein passage of the electric field through the dividing cells in late anaphase or telophase transforms the electric field into a non-homogeneous electric field that produces an increased density electric field in a region of the dividing cells to induce a structural change in the dividing cell resulting in destruction thereof, the optimization method comprising the steps of:

computing an optimal field map of the positions of electrodes relative to the malcontrolled cell growth in a target area;

arranging the electrodes according to a select pattern relative to the malcontrolled cell growth and computing a vector sum of electric fields to generate an electric field map;

comparing the electric field map to the optimal field map;

changing one of a delivered voltage to the electrodes and a location of the electrodes and computing a vector sum of electric fields to generate an electric field map for the electrodes;

optimizing a correlation between the calculated electric field map and the optimal field map, wherein the optimization step takes into account the electrode voltage, wave shape and position of each electrode; and

wherein

the electric field is computed in accordance with the expression;

$E=\frac{V}{r<br><br>\text{\hspace{1em}<br><br>}<br><br>\ln <br><br>\left(\frac{R_2}{R_1}\right)}<br><br>\frac{{\mathrm{\varepsilon <br><br>}}_{\mathrm{coat}}}{{\mathrm{\varepsilon <br><br>}}_{\mathrm{tissue}}}$

where R₁ is the radius of a conductive part of the electrode;

R₂ is the electrode radius including a coating disposed on the electrode; and

∈

_coat and ∈

_tissue are the dielectric constants of the electrode coating and tissue, respectively and r is the distance between the electrodes to the point where one wants to calculate the electric field.

2. The method of claim 1, wherein the step of computing an optimal field map includes the steps of:

(a) inputting characteristics of tissue cells in the target area;

(b) inputting characteristics of the malcontrolled tissue cells in the target area;

(c) inputting anatomical characteristics of the target area;

(d) computing a threshold field intensity in the malcontrolled cell growth;

(e) computing relative sensitivities of surrounding healthy tissue to the electric fields;

(f) computing a maximal allowed field intensity at predetermined locations; and

(g) computing the optimal field map on the basis of the information generated in steps (a) to (f).

3. The method of claim 1, wherein device includes:

a first insulated electrode having a first conductor;

a second insulated electrode having a second conductor; and

an electric field source connected to the first and second insulated electrodes for applying the alternating electric field across the first and second conductors to create a condition in the dividing cells that encourages the destruction thereof.

4. The method of claim 3, wherein the first electrode includes a first dielectric member that is in contact with the first conductor, the first dielectric member for placement against the living tissue to form a capacitor and wherein the second electrode includes a second dielectric member that is in contact with the second conductor, the second dielectric member for placement against the living tissue to form a capacitor.

5. The method of claim 1, wherein the alternating electric field has a frequency of between about 50 KHz to about 500 KHz.

6. The method of claim 1, wherein the alternating electric field has a frequency of between about 100 KHz to about 300 KHz.

7. The method of claim 3, wherein the electric field source comprises a generator that generates an alternating voltage waveform at frequencies between about 50 KHz to about 500 KHz.

8. The method of claim 7, including the step of:

activating the first and second electrodes by the alternating voltage waveform.

9. The method of claim 1, wherein the coating of the electrode comprises a potassium tantalate coating.

10. The method of claim 1, wherein the step of optimizing a correlation comprises the step of:

applying a robust numeric optimization method to optimize the correlation between the calculated electric field map and the optimal field map.

11. The method of claim 1, wherein the select pattern is one of a symmetric pattern and a non-symmetric pattern.

12. The method of claim 1, wherein the step of computing a vector sum comprises the steps of:

feeding coordinates of all available electrodes; and

computing the vector sum of the fields generated by each electrode at each point in time.

13. The method of claim 1, wherein the optimization step includes balancing the strength of the electric field at the malcontrolled cell growth and maximizing a difference between electric field strength at the malcontrolled cell growth and the electric field strength at surrounding healthy tissue.

14. The method of claim 1, wherein the tissue is muscle tissue and ∈

_tissue equals ∈

_muscle.

16. The method of claim 14, wherein positioning the first and second insulated electrodes comprises:

placing the first and second electrodes against a chest wall and positioning the electrodes so that the heart and the targeted artery fall within a high density region of the electric field.

17. The method of claim 14, further including the step of:

placing a stent within the artery, the mass of proliferating cells growing at or near the stent.

18. The method of claim 16, wherein the stent comprises a conductive stent.

19. The method of claim 14, wherein the alternating electric potential has a frequency of between about 100 KHz to about 300 KHz.

15. A method to prevent restenosis of arteries after angioplasty, the method comprising the steps of:

providing an apparatus having;

a first insulated electrode;

a second insulated electrode; and

an electric field source for applying an alternating electric field across the first and second conductors;

positioning the first and second insulated electrodes in relation to at least one mass of proliferating cells within at least one artery; and

subjecting the one or more masses of proliferating cells to an alternating electric field, wherein passage of the electric field through the proliferating cells in late anaphase or telophase transforms the electric field into a non-homogeneous electric field that produces an increased density electric field in a region of the cells and induces a structural change in the cells resulting in destruction thereof, wherein subjecting the living tissue to the alternating electric field comprises applying an alternating electric potential having a frequency of between about 50 KHz to about 500 KHz.