System for monitoring ablation size

• US 8,568,401 B2
• Filed: 10/27/2009
• Issued: 10/29/2013
• 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:
  US12/606,769
• Publication Number:
  US 20110098695A1
• Time in Patent Office: 1,463 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 parameters 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 including at least one memory storage device accessible by the microprocessor and including data specific to the microwave antenna, the 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 complex impedance associated with the data specific to the microwave antenna, complex impedance corresponding to a radius of the ablation zone, wherein the ablation zone control module is programmed to perform the following steps;

measure a phase difference between forward and reflected power generated by the power source to calculate an imaginary portion of the complex impedance;

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

trigger a signal when a predetermined threshold value of the complex impedance is measured corresponding to the radius of the ablation zone.

2. A system according to claim 1, wherein the complex impedance is measured during transmission of microwave energy to the microwave antenna when the microwave antenna is disposed near ablated tissue.

3. A system according to claim 2, 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.

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

5. 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.

6. 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.

7. 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;

at least one memory storage device accessible by a microprocessor of the power source and including data specific to the microwave antenna; 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 complex impedance associated with the data specific to the microwave antenna, the complex impedance corresponding to a radius of the ablation zone, wherein the ablation zone control module is programmed to perform the following steps;

measure a phase difference between forward and reflected power generated by the power source to calculate an imaginary portion of the complex impedance;

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

trigger a signal to the power source when a predetermined threshold value of the complex impedance is measured corresponding to the radius of the ablation zone.

8. A system according to claim 7, wherein the complex impedance is measured during transmission of microwave energy to the microwave antenna when the microwave antenna is disposed near ablated tissue.