System and Method for Monitoring Ablation Size

• US 20110098695A1
• Filed: 10/27/2009
• Published: 04/28/2011
• Est. Priority Date: 10/27/2009
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Vivant Medical, Inc. (Johnson Controls International plc)
• Inventors: Brannan, Joseph D.
• Granted Patent: US 8,568,401 B2
• Time in Patent Office: Days
• US Class Current: 606/33
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/18 by applying electromagnetic radiation, e.g. microwaves radiation therapy A61N5/00
• CPC Class Codes: A61B 18/1815 using microwaves
• CPC Class Codes: A61B 2018/00023 closed, i.e. without wound contact by the fluid
• CPC Class Codes: A61B 2018/00684 using lookup tables
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61N 5/045 specially adapted for treatment inside the body

Abstract

A system for monitoring ablation size is provided and includes a power source including a microprocessor for executing at least one control algorithm. A microwave antenna is configured to deliver microwave energy from the power source to tissue to form an ablation zone. An ablation zone control module is in operative communication with memory associated with the power source. The memory includes one or more data look-up tables including one or more electrical parameter associated with the microwave antenna. The one or more electrical parameters corresponding to an ablation zone having a radius. The one or more electrical parameters include a threshold value, wherein when the threshold value is met the power source is adjusted to form an ablation zone of suitable proportion.

Claims

1. A system for monitoring ablation size, comprising:

a power source including a microprocessor for executing at least one control algorithm;

a microwave antenna configured to deliver microwave energy from the power source to tissue to form an ablation zone; and

an ablation zone control module in operative communication with a memory associated with the power source, the memory including at least one data look-up table including at least one electrical parameter associated with the microwave antenna, the at least one electrical parameter corresponding to a radius of the ablation zone, wherein the ablation zone control module triggers a signal when a predetermined threshold value of the at least one electrical parameter is measured corresponding to the radius of the ablation zone.

2. A system according to claim 1, wherein the at least one electrical parameter is selected from the group consisting of impedance, power, voltage and current.

3. A system according to claim 2, wherein the impedance is complex impedance associated with the microwave antenna during transmission of microwave energy to the microwave antenna when the microwave antenna is in a near field of ablated tissue.

4. A system according to claim 3, wherein the at least one control algorithm calculates complex impedance associated with the microwave antenna when at least a portion of the microwave antenna and ablated tissue are in a steady-state condition relative to each other.

5. A system according to claim 4, wherein the variables required to calculate complex tissue impedance are selected from the group consisting of impedance, power, voltage and current.

6. A system according to claim 5, wherein the variable is power associated with a forward and reflected signal generated by the power source.

7. A system according to claim 1, wherein the microwave antenna is configured to produce an ablation zone that is one of spherical and ellipsoidal.

8. A system according to claim 1, further comprising:

at least one fluid pump configured to supply a cooling fluid to the microwave antenna for facilitating cooling of one of the microwave antenna and tissue adjacent the ablation zone.

9. A system according to claim 1, further comprising:

a calibration module operably connected to a network analyzer configured to determined line losses associated with one of a connector and internal cable of the microwave antenna.

10. A method for monitoring temperature of tissue undergoing ablation, the method comprising:

transmitting microwave energy from a power source to a microwave antenna to form a tissue ablation zone;

monitoring complex impedance associated with the microwave antenna as the tissue ablation zone forms;

communicating a control signal to the power source when a predetermined complex impedance is reached at the microwave antenna; and

adjusting the amount of microwave energy from the power source to the microwave antenna.

11. A method according to claim 10, wherein the step of monitoring tissue further includes the step of providing an ablation zone control module operably coupled to a memory associated with the power source, the memory including at least one data look-up table including at least one electrical parameter associated with the microwave antenna, the at least one electrical parameter corresponding to a radius of the ablation zone, wherein the ablation zone control module triggers a signal when a predetermined threshold value of the at least one electrical parameter is measured corresponding to the radius of the ablation zone.

12. A method according to claim 11, wherein the step of providing an ablation zone control module includes providing at least one electrical parameter that is selected from the group consisting of impedance, power, voltage and current.

13. A method according to claim 12, wherein the step of providing an ablation zone control module includes providing that the impedance is complex impedance associated with the microwave antenna during transmission of microwave energy to the microwave antenna when the microwave antenna is in a near field of ablated tissue.

14. A method according to claim 13, wherein at least one control algorithm calculates complex impedance associated with the microwave antenna when at least a portion of the microwave antenna and ablated tissue are in a steady-state condition relative to each other.

15. A method according to claim 14, wherein the variables required to calculate complex impedance are selected from the group consisting of impedance, power, voltage and current.

16. A method according to claim 15, wherein the variable is power associated with a forward and reflected signal generated by the power source.

17. A method according to claim 10, wherein the microwave antenna is configured to produce an ablation zone that is spherical.

18. A microwave antenna adapted to connect to a power source configured for performing an ablation procedure, comprising:

a radiating section configured to deliver microwave energy from a power source to tissue to form an ablation zone; and

an ablation zone control module operably coupled to a memory associated with the power source, the memory including at least one data look-up table including at least one electrical parameter associated with the microwave antenna, the at least one electrical parameter corresponding to a radius of the ablation zone, wherein the ablation zone control module triggers a signal to the power source when a predetermined threshold value of the at least one electrical parameter is measured corresponding to the radius of the ablation zone.

19. A system according to claim 18, wherein the at least one electrical parameter is selected from the group consisting of impedance, power, voltage and current.

20. A system according to claim 19, wherein the impedance is complex impedance associated with the microwave antenna during transmission of microwave energy to the microwave antenna when the microwave antenna is in a near field of ablated tissue.