SYSTEM AND METHOD FOR ESTIMATING TISSUE HEATING OF A TARGET ABLATION ZONE FOR ELECTRICAL-ENERGY BASED THERAPIES
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.
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 electric field distribution in a tissue surrounding the electrodes based on the one or more parameters;
displaying a graphical representation of the heat and/or electric field distribution based on the modeled heat distribution in the display device;
modifying one or more of the parameters of the treatment protocol based on the graphical representation of the heat 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.
2 . 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, a change in conductivity for the target treatment area, or a conductivity for a specific tissue type.
3 . 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
displaying a graphical representation of the modeled heat and/or electric field distribution.
4 . The method of claim 3 , 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, C p is the heat capacity, k is the thermal conductivity, and Q jh 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
]
.
5 . The method of claim 3 , 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.
6 . The method of claim 3 , 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.
7 . The method of claim 6 , wherein the electric field distribution is calculated as:
∇
2
ϕ
=
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=V in 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 V in is the electrical potential applied.
8 . The method of claim 6 , further comprising specifying a cutoff electrical field distribution value and providing a graphical representation of the electrical field distribution value as an isocontour line.
9 . The method of claim 3 , 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, a change in conductivity for the target treatment area, or a conductivity for a specific tissue type.
10 . The method of claim 8 , further comprising one or more databases comprising a plurality of sets of parameters for treatment protocols stored in the database.
11 . The method of claim 10 , wherein the graphical representations of the modeled heat and electrical field distributions are derived from Cassini oval calculations.
12 . 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 electrical pulses to tissue through one or more electrodes;
model heat and/or electric field distribution in the tissue based on the parameters;
display a graphical representation of the modeled heat and/or electric field distribution on the display device.
13 . The system of claim 12 , further comprising one or more databases comprising a plurality of sets of parameters for treatment protocols stored in the databases.
14 . The system of claim 12 , 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, a change in conductivity for the target treatment area, or a conductivity for a specific tissue type.
15 . The system of claim 14 , wherein the change in conductivity is expressed as a ratio of the baseline conductivity to the maximum conductivity of the tissue that is reached during treatment.
16 . The system of claim 14 , wherein the conductivity for a specific tissue type is provided in a database for a plurality of tissues.
17 . The system of claim 12 , wherein the one or more electrodes is provided by one or more bipolar probes.
18 . The system of claim 12 , wherein the one or more electrodes are provided by one or more single needle electrodes.
19 . The system of claim 15 , wherein the change in conductivity is calculated in real-time based on measured voltages and currents before, during, and/or after pulse delivery.
20 . The method of claim 6 , wherein the graphical representation of the modeled thermal damage and/or electrical damage is derived from Cassini oval calculations.