Monopole phased array thermotherapy applicator for deep tumor therapy

• US 20040044385A1
• Filed: 09/03/2002
• Published: 03/04/2004
• Est. Priority Date: 09/03/2002
• Status: Active Grant

• Current Assignee: Celsion Corporation
• Original Assignee: Celsion Corporation
• Inventors: Fenn, Alan J., Mon, John, Smith, Dennis
• Granted Patent: US 6,807,446 B2
• Time in Patent Office: Days
• US Class Current: 607/100
• CPC Class Codes: A61N 1/403 for thermotherapy, e.g. hyperthermia

Abstract

A monopole phased array thermotherapy applicator radiating radiofrequency energy for inducing a temperature rise in a target within a body includes a plurality of monopole elements each for transmitting electric-field radiation; a metallic waveguide with an RF reflecting ground plane surface with a plurality of circular holes for mounting the monopole elements where the metallic waveguide forms an aperture for receiving a body to be treated; a waveform generator providing a source of electric field coupled to each monopole radiating element through a respective phase and power weighting network; at least one electric field probe positioned on a skin surface of the body for detecting electric field radiation from the plurality of monopole elements; and a controller circuit coupled to the electric field probe received feedback signals to adjust the phase and power delivered to the plurality of monopole elements so that one or more adaptive nulls are formed on the surface of the body and a focus is formed at the target tissue to be treated with thermotherapy.

Claims

1. A monopole phased array thermotherapy applicator radiating radiofrequency energy for inducing a temperature rise in a target within a body, comprising:

a) a plurality of monopole elements each for transmitting electric-field radiation;

b) a metallic waveguide with an RF reflecting ground plane surface with a plurality of circular holes for mounting the monopole elements, the metallic waveguide forming an aperture for receiving a body to be treated;

c) a waveform generator providing a source of electric field coupled to each monopole radiating element through a respective phase and power weighting network;

d) at least one electric field probe positioned on a skin surface of the body for detecting electric field radiation from the plurality of monopole elements; and

e) a controller circuit coupled to the electric field probe received feedback signals to adjust the phase and power delivered to the plurality of monopole elements so that one or more adaptive nulls are formed on the surface of the body and a focus is formed at the target tissue to be treated with thermotherapy.

2. The apparatus of claim 1, wherein the radiofrequency energy is in the 80 to 120 MHz band.

3. The applicator of claim 1, wherein the monopole elements have a length between 7 cm and 12 cm.

4. The applicator of claim 1, wherein the monopole elements have a diameter approximately between 0.1 cm and 0.5 cm.

5. The applicator of claim 1, wherein the metallic waveguide structure enclosing the monopole elements forms an elliptical treatment aperture surrounding the body.

6. The applicator of claim 5, wherein a water bolus with cooled distilled or deionized water is used to couple the radiofrequency energy radiated by the monopole elements into the body.

7. The applicator of claim 6, wherein an air gap region cooled by one of air-conditioned and room temperature air supplied by fans or tubes is used to couple the radiofrequency energy radiated by the monopole elements into the body.

8. The applicator of claim 1, wherein the monopole elements are arranged in a ring with diameter approximately between 50 and 70 cm.

9. The applicator of claim 1, wherein the monopole elements are spaced between 6 and 10 cm from the reflecting ground plane surface behind the monopole elements.

10. The applicator of claim 1, wherein the patient treatment aperture has a major axis of a length ranging from approximately 42 cm to 52 cm and a minor axis of a length approximately between 30 and 38 cm.

11. The applicator of claim 1, wherein the patient is supported on a flat non-conducting surface within the treatment aperture of the monopole array applicator.

12. The applicator of claim 1, wherein the patient is supported on a Kevlar or cloth surface supported by non-conducting cylindrical tubes within the treatment aperture of the monopole array applicator.

13. The applicator of claim 1, further comprising at least one temperature sensor positioned outside the body that senses the temperature of the body wherein feedback signals from the at least one electric field probe and the at least one temperature sensor outside the body are coupled to a computer controller circuit to control a phase shifter and power amplifier network to adjust the phase and power delivered to the monopole elements to form one or more nulls on the body'"'"'s skin surface, while focusing energy at a deep tissue site within the body to heat the deep tissue site to the range from about 39 to about 46 degrees Celsius.

14. The applicator of claim 13, wherein the magnitude of the nulls formed on the body'"'"'s skin surface and the focus in the tissue treatment region is controlled by an adaptive phased array fast acceleration gradient search computer algorithm that adjusts the phase and power delivered to the monopole elements.

15. The applicator of claim 14, wherein the focused radiofrequency energy heats the target tissue and releases drug from thermosensitive liposomes circulating within the bloodstream in the vicinity of the target tissue.

16. The applicator of claim 15, wherein the target tissue is one of the liver, lung, breast, prostate, pancreas, stomach, rectum, colon, bladder, and other deep organs of the body.

17. The applicator of claim 14, wherein the focused radiofrequency energy heats the target tissue and enhances the effectiveness of chemotherapy or drugs circulating within the bloodstream in the vicinity of the target tissue.

18. The applicator of claim 17, wherein the target tissue is one of the liver, lung, breast, prostate, pancreas, stomach, rectum, colon, bladder, and other deep organs of the body.

19. The applicator of claim 14, wherein the focused radiofrequency energy heats the target tissue and enhances the effectiveness of radiation therapy delivered at the target tissue.

20. The applicator of claim 19, wherein the target tissue is one of the liver, lung, breast, prostate, pancreas, stomach, rectum, colon, bladder, and other deep organs of the body.

21. The applicator of claim 14, wherein the focused radiofrequency energy heats the target tissue and enhances the effectiveness of gene therapy circulating within the bloodstream in the vicinity of the target tissue.

22. The applicator of claim 14, wherein a radiofrequency energy dose between about 0.5 megajoules and about 2.5 megajoules is delivered to the monopole array applicator to therapeutically heat the target tissue.

23. The applicator of claim 14, wherein the internal tissue temperatures are monitored with an invasive temperature sensor placed in a catheter.

24. The applicator of claim 14, wherein the internal tissue temperatures are monitored noninvasively with one of passive radiofrequency radiometry, applied potential tomography, passive or active ultrasound radiometry or other noninvasive thermotherapy techniques.

25. The applicator of claim 14, wherein an equivalent thermal dose of approximately 30 to 120 minutes relative to 43 degrees Celsius is delivered to the target tissue.

26. The applicator of claim 14, wherein the target tissue is one of precancerous, cancerous, benign, infected, arthritic, human immunodeficiency virus, and other diseased tissue.

27. The applicator of claim 1, wherein each monopole element is driven non-coherently with separate oscillators.

28. The applicator of claim 1, wherein the body is supported within the aperture of the monopole array applicator by means of a flat rigid support.

29. The applicator of claim 1, wherein the body is supported within the aperture of the monopole array applicator by means of a Kevlar or cloth material supported between two cylindrical rods.

30. The applicator of claim 1, wherein the monopole waveguide cavity is made of an acrylic plastic material so that an internal tissue temperature can be monitored noninvasively by one of magnetic resonance imaging, passive radiofrequency radiometry, applied potential tomography, passive or active ultrasound radiometry, and other noninvasive thermometry techniques.

31. A monopole phased array thermotherapy applicator according to claim 1, wherein a single applicator is used to induce the temperature rise in the target within the body.

32. A monopole phased array thermotherapy applicator according to claim 1, wherein two or more applicators are used to induce the temperature rise in the target within the body.

33. A monopole phased array thermotherapy applicator according to claim 1, further comprising an applicator support upon which the metallic waveguide rests or is suspended wherein the applicator support and metallic waveguide are moveable along at least one axis of the body.

34. A monopole phased array thermotherapy applicator according to claim 1, further comprising a non-conducting support for holding a body within the metallic waveguide aperture, the non-conducting support being moveably mounted within the metallic waveguide aperture.

35. A monopole phased array thermotherapy applicator according to claim 34, wherein the non-conducting support is mounted so that it is moveable along the x, y, and z axis of a target body.

36. A monopole phased array thermotherapy applicator according to claim 1, wherein the monopole elements are arranged in a ring with a diameter up to about 90 cm.

37. A monopole phased array thermotherapy applicator according to claim 1, wherein the metallic waveguide is made from one of aluminum and metallized fiberglass or plastic.

38. A monopole phased array thermotherapy applicator according to claim 37, wherein the metallized fiberglass or plastic is one of continuously metallized, and formed of conducting mesh or conducting wires.

39. A monopole phased array thermotherapy applicator according to claim 1, wherein the metallic waveguide forms a portion of a circle and the aperture for receiving the body is beneath an arc of the metallic waveguide.

40. A monopole phased array thermotherapy applicator according to claim 1, wherein the monopole elements form a ring about the body to be treated and the controller circuit activates and deactivates the monopole elements to focus the RF radiation at the target body.