Methods for selectively dissolving and removing materials using ultra-high frequency ultrasound

• US 20020000763A1
• Filed: 08/31/2001
• Published: 01/03/2002
• Est. Priority Date: 11/20/1998
• Status: Active Grant

• Current Assignee: Joie P. Jones
• Original Assignee: Joie P. Jones
• Inventors: Jones, Joie P.
• Granted Patent: US 6,685,657 B2
• Time in Patent Office: Days
• US Class Current: 310/337
• CPC Class Codes: A61B 17/22012 in direct contact with, or very close to, the obstruction or concrement for removing obstructions in blood vessels by laser A61B18/245
• CPC Class Codes: A61B 2017/00274 Prostate operation, e.g. prostatectomy, turp, bhp treatment
• CPC Class Codes: A61B 2018/00547 Prostate

Abstract

The present invention provides processes and apparatus for selectively dissolving and removing unwanted solid and semi-solid materials and the like, within a highly localized region utilizing ultra-high energy acoustical waves having a frequency in the range above 50 MHz, for example from about 50 MHz to about 100 GHz. The invention apparatus includes a piezoelectric transducer that is modified to increase the amplitude of acoustical waves of a given frequency without increase in power to the system. The invention and apparatus have important applications in surgical procedures for the treatment of atherosclerotic plaque, prostate disorders, cancers, orthopedic and cosmetic surgery, various types of orthopedic surgery, including atheroscopic surgery, and the like. The present invention is also useful in a wide variety of non-surgical applications, including industrial processes, wherein materials are desired to be selectively removed in a very localized region.

Claims

1. A method for causing dissolution of unwanted solid or semi-solid material, said method comprising forming ultrasonic acoustical waves having a frequency greater than 50 MHz and a sufficient amplitude to cause selective dissolution of the unwanted material without substantial damage to surrounding material, and applying the waves to the unwanted material via a zone of acoustical impedance mismatch to cause said dissolution thereof.

2. A method according to claim 1 wherein the unwanted material is soft tissue.

3. A method according to claim 2 wherein the soft tissue is located at an inaccessible body site.

4. A method according to claim 3 wherein the source of the waves is at least one piezoelectric transducer located at the tip of a catheter, and the applying involves emplacement of the catheter so that the active face of the at least one transducer is in contact with the unwanted tissue at the inaccessible body site.

5. A method according to claim 2 wherein the source of the waves is at least one piezoelectric transducer, and the applying involves repeatedly rubbing the active face of the transducer across the surface of the unwanted tissue.

6. A method according to claim 2 wherein the soft tissue is selected from the group consisting of atherosclerotic build-up, benign prostatic hyperplasia tissue, prostatic cancer, and liver cancer.

7. A method according to claim 2 wherein the soft tissue is atherosclerotic build-up.

8. A method according to claim 7 wherein the build-up is atherosclerotic plaque.

9. A method according to claim 6 wherein the soft tissue is prostate tissue.

10. A method according to claim 1 wherein the ultrasonic acoustical waves have a substantial transverse component.

11. A method according to claim 1 wherein the substantial transverse component is superimposed on a longitudinal component of the waves.

12. A method according to claim 1 wherein the ultrasonic acoustical waves form rings of alternating high and low pressure on the face of the transducer.

13. A method according to claim 1, wherein the applying involves interposition of a layer of highly elastic material of about 1 wavelength in thickness between the source of the waves and the unwanted material.

14. A method according to claim 1 wherein the dissolution is into subcellular particles.

15. A method according to claim 14 wherein the dimension of the particles is determined by the selection of the frequency.

16. A method according to claim 1 wherein the waves have a frequency in the range from 50 MHz to about 120 MHz and a Spatial Peak Temporal Averaged Intensity greater than 100 mW/cm².

17. A method according to claim 1 wherein the acoustical energy of the waves is below the cavitation threshold in water.

18. A method according to claim 1 wherein the waves are applied in a series of pulses.

19. A method according to claim 18 wherein the pulses are in the range from about 10 to 100 wavelengths in duration.

21. A method according to claim 19 wherein the waves have a frequency in the range from about 50 MHz to about 100 GHz.

22. A method according to claim 19 wherein the waves have a frequency in the range from about 80 MHz to about 120 MHz.

23. A method according to claim 19 wherein the ultrasonic acoustical waves have a substantial transverse component.

24. A method according to claim 23 wherein the substantial transverse component is superimposed on a longitudinal component of the waves.

25. A method according to claim 1 wherein the ultrasonic acoustical waves form rings of alternating high and low pressure on the face of the transducer.

26. A method according to claim 19 wherein the applying involves interposition of a layer of highly elastic material of about 1 wavelength in thickness between the source of the waves and the unwanted material.

27. A method according to claim 19 wherein the acoustical energy of the waves is below the cavitation threshold in water.

20. A method of treating benign prostatic hyperplasia in a subject in need, said method comprising forming ultra-high frequency acoustical waves having a frequency greater than 50 MHz and a sufficient amplitude to cause selective dissolution of the unwanted prostatic tissue without substantial damage to surrounding tissue, and applying the waves to the unwanted tissue in the subject via a zone of acoustical impedance mismatch to cause said dissolution thereto.

28. A method of treating cancer in a subject in need thereof, said method comprising forming ultra-high frequency acoustical waves having a frequency greater than 50 MHz and a sufficient amplitude to cause selective dissolution of cancerous tissue without substantial damage to surrounding tissue, and applying the waves to the cancerous tissue in the subject via a zone of acoustical impedance mismatch to cause said dissolution thereof.

29. A method according to claim 28 wherein said cancer is prostate cancer.

30. A method according to claim 28 wherein said cancer is liver cancer.

31. A method of shaping hard tissue in a subject in need thereof, said method comprising forming ultras-high frequency acoustical waves having a frequency greater than 50 MHz and a sufficient amplitude to cause selective dissolution to one or more unwanted portions of the hard tissue without substantial damage to surrounding portions of the hard tissue, and applying the waves to the one or more unwanted portions in the subject via a zone of acoustical impedance mismatch to cause said dissolution thereof.

32. A method of shaping soft tissue, said method comprising forming ultra-high frequency acoustical waves having a frequency greater than 50 MHz and a sufficient amplitude to cause selective dissolution to one or more unwanted portions of the soft tissue without substantial damage to surrounding portions of the soft tissue, and applying the waves to the one or more unwanted portions in the subject via a zone of acoustical impedance mismatch to cause said dissolution thereto.