System and method for monitoring ablation size

• US 8,894,641 B2
• Filed: 10/28/2013
• Issued: 11/25/2014
• Est. Priority Date: 10/27/2009
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Brannan, Joseph D.
• Primary Examiner(s): Dvorak, Linda
• Assistant Examiner(s): Ram, Jocelyn D
• Application Number:
  US14/064,846
• Publication Number:
  US 20140052124A1
• Time in Patent Office: 393 Days
• Field of Search: 606/33, 606/34, 606/41, 607/101
• US Class Current: 606/34
• 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 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;

measuring a phase difference between forward and reflected power generated by the power source to calculate an imaginary portion of complex impedance associated with the microwave antenna as the tissue ablation zone forms;

measuring a magnitude difference between the forward and reflected power to calculate a real portion of the complex impedance;

triggering a control signal when a predetermined threshold value of the complex impedance is measured corresponding to a radius of the tissue ablation zone; and

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

2. The method according to claim 1, wherein measuring a phase difference between forward and reflected power includes utilizing an ablation control module associated with the power source.

3. The method according to claim 1, further including, when the microwave antenna is disposed near the tissue ablation zone, executing at least one control algorithm via a microprocessor of the power source to calculate the complex impedance of the microwave antenna.

4. The method according to claim 3, further including, when at least a portion of the microwave antenna and ablated tissue are in a steady-state condition relative to each other, executing the at least one control algorithm to calculate the complex impedance of the microwave antenna.

5. The method according to claim 3, further including providing the microwave antenna with at least one memory storage device accessible by the microprocessor, the at least one memory storage device including at least one data look-up table including the complex impedance associated with data specific to the microwave antenna.

6. The method according to claim 1, further including producing the tissue ablation zone with a shape that is one of a spherical and ellipsoidal.

7. The method according to claim 1, further including providing a cooling fluid to the microwave antenna for cooling one of the microwave antenna and tissue adjacent the tissue ablation zone.

8. The method according to claim 7, wherein providing a cooling fluid includes utilizing at least one fluid pump to supply the cooling fluid to one of the microwave antenna and tissue adjacent the tissue ablation zone.