# US 10,117,707 B2 · System and method for estimating tissue heating of a target ablation zone for electrical-energy based therapies

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- Number: US 10,117,707 B2
- Document ID: US10117707B2
- Status: Granted
- Kind: B2
- Application number: 14/558,631
- Filed: 2014-12-02
- Published: 2015-03-26
- Granted: 2018-11-06
- Earliest claimed: 2008-04-29
- Assignees: Virginia Tech Intellectual Properties, Inc.
- Applicants: Virginia Tech Intellectual Properties Inc.
- Inventors: Paulo A. Garcia; Christopher B. Arena; Michael B. Sano; Rafael V. Davalos
- Web page: https://patentgrep.com/patent/US10117707B2

## CPC

- A61B 18/1477: {Needle-like probes}
- A61B 34/10: Computer-aided planning, simulation or modelling of surgical operations
- C12N 13/00: Treatment of microorganisms or enzymes with electrical or wave energy, e.g. magnetism, sonic waves
- A61B 34/25: {User interfaces for surgical systems}
- A61B 90/37: {Surgical systems with images on a monitor during operation}
- A61B 2018/0016: {Energy applicators arranged in a two- or three dimensional array}
- A61B 2018/00613: {Irreversible electroporation}
- A61B 2018/00779: {Power or energy}
- A61B 2018/00875: {Resistance or impedance}
- A61B 2018/00886: {Duration}
- A61B 2018/00892: {Voltage}
- A61B 2018/1425: {Needle}
- A61B 2034/104: {Modelling the effect of the tool, e.g. the effect of an implanted prosthesis or for predicting the effect of ablation or burring}
- A61B 2034/256: {having a database of accessory information, e.g. including context sensitive help or scientific articles}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- C12N: MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA (microbiological testing media C12Q1/00)

## Abstract

Systems and methods are provided for modeling and for providing a graphical representation of tissue heating and electric field distributions for medical treatment devices that apply electrical treatment energy through one or a plurality of electrodes. In embodiments, methods comprise: providing one or more parameters of a treatment protocol for delivering one or more electrical pulses to tissue through a plurality of electrodes; modeling electric and heat distribution in the tissue based on the parameters; and displaying a graphical representation of the modeled electric and heat distribution. In another embodiment, a treatment planning module is adapted to generate an estimated target ablation zone based on a combination of one or more parameters for an irreversible electroporation protocol and one or more tissue-specific conductivity parameters.

## Claims

### Claim 1

A method of treating a tissue with a medical treatment device that applies electrical treatment energy through one or more electrodes defining a target treatment area of the tissue and comprises a display device, the method comprising:
providing one or more parameters of a treatment protocol for delivering one or more electrical pulses to a tissue through one or more electrodes;
modeling heat distribution and/or the electric field distribution in a tissue surrounding the electrodes based on the one or more parameters and a treatment protocol-related change in electrical conductivity for the target treatment are, which is a ratio of a maximum electrical conductivity that is reached during treatment to a baseline, non-electroporated, tissue-specific electrical conductivity;
displaying a graphical representation of the heat and/or electric field distribution based on the modeled heat and/or electric field distribution in the display device;
modifying one or more of the parameters of the treatment protocol based on the graphical representation of the heat and/or electric field distribution; and
implanting the electrodes in the tissue and delivering one or more electrical pulses to the tissue through the electrodes by way of a voltage pulse generator based on the one or more modified parameters.

### Claim 2 (depends on 1)

The method of claim 1, wherein the one or more parameters are chosen from one or more of voltage, electrode spacing, electrode length, treatment duration, number of pulses, pulse width, electric field intensity, electrode diameter, a baseline conductivity for the target treatment area, or a conductivity for a specific tissue type.

### Claim 3 (depends on 1)

The method of claim 1, wherein the treatment protocol-related change in electrical conductivity is calculated in real time based on measured voltages and currents before, during, and/or after pulse delivery.

### Claim 4

A method of treatment planning for medical therapies involving administering electrical treatment energy, the method comprising:
providing one or more parameters of a treatment protocol for delivering one or more electrical pulses to tissue through one or more electrodes;
modeling heat and/or electric field distribution in the tissue based on the parameters and a treatment protocol-related change in electrical conductivity for the target treatment area, which is a ratio of a maximum electrical conductivity that is reached during treatment to a baseline, non-electroporated, tissue-specific electrical conductivity; and
displaying a graphical representation of the modeled heat and/or electric field distribution.

### Claim 5 (depends on 4)

The method of claim 4, wherein the heat distribution is modeled to estimate the Joule heating in the tissue and is calculated as:
ρ
⁢
⁢
C
p
⁢
∂
T
∂
t
=
∇
·
(
k
⁢
∇
T
)
+
Q
jh
⁡
[
W
m
3
]
where ρ is the density, Cp is the heat capacity, k is the thermal conductivity, and Qjh are the resistive losses
Q
jh
=
J
·
E
⁡
[
W
m
3
]
where J is the induced current density
J
=
σ
⁢
⁢
E
⁡
[
A
m
2
]
and σ is the tissue conductivity and E is the electric field
E
=
-
∇
ϕ
⁡
[
V
m
]
.

### Claim 6 (depends on 4)

The method of claim 4, further comprising specifying a cutoff heat distribution value and providing a graphical representation of the heat and/or electric field distribution curve as an isocontour line.

### Claim 7 (depends on 4)

The method of claim 4, further comprising:
modeling an electrical damage and/or a thermal damage in the tissue based on the parameters;
displaying a graphical representation of the modeled electrical damage and/or thermal damage.

### Claim 8 (depends on 7)

The method of claim 7, wherein the electric field distribution is calculated as:
∇2ϕ=0
where ϕ is the electric potential, this equation is solved with boundary conditions:
{right arrow over (n)}·{right arrow over (J)}=0 at the boundaries
ϕ=Vin at the boundary of the first electrode
ϕ=0 at the boundary of the second electrode
wherein {right arrow over (n)} is the normal vector to the surface, {right arrow over (J)} is the electrical current and Vin is the electrical potential applied.

### Claim 9 (depends on 7)

The method of claim 7, further comprising specifying a cutoff electrical field distribution value and providing a graphical representation of the electrical field distribution value as an isocontour line.

### Claim 10 (depends on 9)

The method of claim 9, further comprising one or more databases comprising a plurality of sets of parameters for treatment protocols stored in the database.

### Claim 11 (depends on 10)

The method of claim 10, wherein the graphical representations of the modeled heat and electrical field distributions are derived from Cassini oval calculations.

### Claim 12 (depends on 7)

The method of claim 7, wherein the graphical representation of the modeled thermal damage and/or electrical damage is derived from Cassini oval calculations.

### Claim 13 (depends on 4)

The method of claim 4, wherein the parameters are chosen from one or more of voltage, electrode spacing, electrode diameter, electrode length, number of pulses, treatment duration, pulse width, electric field intensity, a baseline conductivity for the target treatment area, or a conductivity for a specific tissue type.

### Claim 14 (depends on 4)

The method of claim 4, further comprising:
modeling one or more of a thermally damaged region, IRE necrotic region, IRE apoptotic region, reversible electroporation region, and region where there is no effect in the tissue based on the parameters; and
displaying a graphical representation of the modeled regions.

### Claim 15 (depends on 4)

The method of claim 4, further comprising:
modeling one or more of a thermally damaged region, an electroporation region, and a region where there is no effect in the tissue based on the parameters; and
displaying a graphical representation of the modeled regions.

### Claim 16

A system for treatment planning for medical therapies involving administering electrical treatment energy, the system comprising:
a computer comprising:
a memory;
a display device;
a processor coupled to the memory and the display device; and
a treatment planning module stored in the memory and executable by the processor, the treatment planning module adapted to:
receive as input one or more parameters of a treatment protocol for delivering one or more electrical pulses to tissue through one or more electrodes;
model heat and/or electric field distribution in the tissue based on the parameters and a treatment protocol-related change in electrical conductivity for the target treatment area, which is a ratio of a maximum electrical conductivity that is reached during treatment to a baseline, non-electroporated, tissue-specific electrical conductivity;
display a graphical representation of the modeled heat and/or electric field distribution on the display device.

### Claim 17 (depends on 16)

The system of claim 16, further comprising one or more databases comprising a plurality of sets of parameters for treatment protocols stored in the databases.

### Claim 18 (depends on 16)

The system of claim 16, wherein the inputs are chosen from one or more of voltage, electrode spacing, treatment duration, pulse width, electric field intensity, a baseline conductivity for the target treatment area, or a conductivity for a specific tissue type.

### Claim 19 (depends on 18)

The system of claim 18, wherein the conductivity for a specific tissue type is provided in a database for a plurality of tissues.

### Claim 20 (depends on 16)

The system of claim 16, wherein the one or more electrodes is provided by one or more bipolar probes.

### Claim 21 (depends on 16)

The system of claim 16, wherein the one or more electrodes are provided by one or more single needle electrodes.