Miniaturized microwave ablation assembly

• US 10,813,691 B2
• Filed: 10/01/2014
• Issued: 10/27/2020
• Est. Priority Date: 10/01/2014
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Brannan, Joseph D
• Primary Examiner(s): Fowler, Daniel W
• Assistant Examiner(s): Demie, Tigist S
• Application Number:
  US14/503,926
• Publication Number:
  US 20160095657A1
• Time in Patent Office: 2,218 Days
• 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 2018/00577 Ablation
• CPC Class Codes: A61B 2018/1861 with an instrument inserted into a body lumen or cavity, e.g. a catheter

Abstract

Microwave applicators are disclosed which include a first transmission line segment, a second transmission line segment, and a third transmission line segment. The first transmission line segment includes a first inner conductor, a first dielectric disposed on the first inner conductor, and a first outer conductor disposed on the first dielectric. The second transmission line segment includes a second inner conductor, a second dielectric disposed on the second inner conductor, and a second outer conductor disposed on the second dielectric. The third transmission line segment includes a third inner conductor disposed on the third inner conductor, a third outer conductor disposed on the proximal end of the third dielectric. The impedance looking into the second transmission line segment from the first transmission line segment can be adjusted by adjusting the length of the third transmission line segment.

Claims

1. A microwave applicator having a longitudinal axis and coupled to a generator having a generator impedance Z_G, the microwave applicator comprising:

a first transmission line segment including a first inner conductor and a first outer conductor circumscribing the first inner conductor, the first outer conductor having a first outer diameter;

a second transmission line segment including a second inner conductor and a second outer conductor circumscribing the second inner conductor, the second outer conductor having a second outer diameter less than the first outer diameter;

a junction impedance Z_load at a junction of the first transmission line segment and the second transmission line segment; and

a third transmission line segment including a third inner conductor, a third outer conductor circumscribing the third inner conductor, and a dielectric material disposed between the third inner conductor and the third outer conductor, the dielectric material extending distally beyond a distal end of the third outer conductor, the third outer conductor having a third outer diameter less than the second outer diameter,

wherein an impedance of the second transmission line segment is determined based on a length of the third transmission line segment along the longitudinal axis of the microwave applicator, and

wherein the length of the third transmission line segment is configured to match the junction impedance Z_load to the generator impedance Z_G.

2. The microwave applicator according to claim 1, wherein one or more of the first transmission line segment, the second transmission line segment, the third transmission line segment is rigid, semi-rigid, or flexible.

3. The microwave applicator according to claim 1, wherein the diameter of the second and third inner conductors are equal to the diameter of the first inner conductor.

4. The microwave applicator according to claim 1, wherein the second and third inner conductors are an extension of the first inner conductor.

5. The microwave applicator according to claim 1, including a balun outer conductor circumscribing the third outer conductor.

6. The microwave applicator according to claim 5, wherein an outer diameter of the balun outer conductor is equal to the first outer diameter of the first outer conductor of the first transmission line segment.

11. The microwave applicator according to claim 1, wherein the third transmission line segment includes a balun coaxially surrounding the third outer conductor, the third inner conductor, and the dielectric material.

12. The microwave applicator according to claim 1, wherein the dielectric material extending distally beyond a distal end of the third outer conductor defines a feed gap.

7. An antenna assembly coupled to a generator having a generator impedance Z_G, the antenna assembly comprising:

a coaxial cable having an inner conductor and an outer conductor coaxially surrounding the inner conductor, the coaxial cable including;

a first transmission line segment having a first outer diameter,

a second transmission line segment,

a junction impedance Z_load at a junction of the first transmission line segment and the second transmission line segment,

a third transmission line segment having a third outer diameter smaller than the first outer diameter and including a dielectric material disposed between the outer conductor and the inner conductor, the dielectric material extending distally beyond a distal end of the outer conductor, and

a coaxial balun disposed on the third transmission line segment, wherein an outer diameter of the coaxial balun is equal to the first outer diameter,

wherein the coaxial cable has a maximum outer diameter equal to the outer diameter of the coaxial balun and the first outer diameter, and

wherein a length of the third transmission line segment is configured to be greater than a quarter wavelength and is configured to match the junction impedance Z_load to the generator impedance Z_G;

a radiating section formed at a distal end of the third transmission line segment; and

a dielectric buffering and cooling segment configured to receive the coaxial cable and attached to the radiating section, the dielectric buffering and cooling segment having a diameter greater than the maximum outer diameter of the coaxial cable.

8. The antenna assembly according to claim 7, wherein one or more of the first transmission line segment, the second transmission line segment, the third transmission line segment is rigid, semi-rigid, or flexible.

9. The antenna assembly according to claim 7, wherein the dielectric buffering and cooling segment includes a first tube and a second tube disposed within the first tube, the second tube defining an outflow conduit between the inner surface of the first tube and the outer surface of the second tube, and defining an inflow conduit between the inner surface of the second tube and the outer surfaces of the coaxial cable and attached radiating section.

10. The antenna assembly according to claim 7, wherein the dielectric buffering and cooling segment includes a first tube defining inflow and outflow conduits for carrying cooling fluid.

13. The antenna assembly according to claim 7, wherein the coaxial balun coaxially surrounds the outer conductor, the inner conductor, and the dielectric material.

14. The antenna assembly according to claim 7, wherein the dielectric material extending distally beyond a distal end of the outer conductor defines a feed gap.

15. A coaxial cable, comprising:

an inner conductor;

an outer conductor coaxially surrounding the inner conductor;

a first transmission line segment having a first outer diameter;

a second transmission line segment;

a third transmission line segment having a third outer diameter smaller than the first outer diameter and including a dielectric material disposed between the outer conductor and the inner conductor, the dielectric material extending distally beyond a distal end of the outer conductor;

a balun coaxially surrounding the dielectric material and having an outer diameter equal to the first outer diameter, wherein the coaxial cable has a maximum outer diameter equal to the outer diameter of the balun and the first outer diameter; and

a radiating section formed at a distal end of the third transmission line segment.