Laser and acoustic lens for lithotripsy

• US 20020058890A1
• Filed: 03/01/2000
• Published: 05/16/2002
• Est. Priority Date: 03/04/1999
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Makarewicz, Anthony J., Benett, William J., Krulevitch, Peter, Da Silva, Luiz B., London, Richard A., Visuri, Steven R.
• Granted Patent: US 6,491,685 B2
• Time in Patent Office: Days
• US Class Current: 601/4
• CPC Class Codes: A61B 18/26 for producing a shock wave, e.g. laser lithotripsy
• CPC Class Codes: A61B 2018/263 the conversion of laser energy into mechanical shockwaves taking place in a liquid

Abstract

An acoustic focusing device whose acoustic waves are generated by laser radiation through an optical fiber. The acoustic energy is capable of efficient destruction of renal and biliary calculi and deliverable to the site of the calculi via an endoscopic procedure. The device includes a transducer tip attached to the distal end of an optical fiber through which laser energy is directed. The transducer tip encapsulates an exogenous absorbing dye. Under proper irradiation conditions (high absorbed energy density, short pulse duration) a stress wave is produced via thermoelastic expansion of the absorber for the destruction of the calculi. The transducer tip can be configured into an acoustic lens such that the transmitted acoustic wave is shaped or focused. Also, compressive stress waves can be reflected off a high density/low density interface to invert the compressive wave into a tensile stress wave, and tensile stresses may be more effective in some instances in disrupting material as most materials are weaker in tension than compression. Estimations indicate that stress amplitudes provided by this device can be magnified more than 100 times, greatly improving the efficiency of optical energy for targeted material destruction.

Claims

1. A device, comprising:

an optical fiber adapted to transmit laser energy,

a transducer mounted at the distal end of said optical fiber,

said transducer including an absorber,

whereby laser energy transmitted through said optical fiber is directed onto said absorber to produce an acoustic wave for material destruction.

2. The device of claim 1, wherein said transducer includes an acoustic lens.

3. The device of claim 2, wherein said acoustic lens is formed in an end of said transducer.

4. The device of claim 2, wherein said acoustic lens is attached to said transducer.

5. The device of claim 2, wherein said acoustic lens includes means for converting compressive stress waves into tensile stress waves.

6. The device of claim 1, wherein said transducer includes a housing, said housing having a cavity therein containing said absorber, and having a countersink into which the distal end of said optical fiber is mounted.

7. The device of claim 6, wherein said absorber is composed of a dye.

8. The device of claim 6, additionally including an acoustic lens formed in or mounted to an end of said housing.

9. The device of claim 1, wherein said absorber comprises an exogenous absorbing dye.

10. The device of claim 1, in combination with a laser capable of producing short duration, high energy pulses, said pulses being transmitted through said optical fiber onto said absorber.

11. The combination of claim 10, wherein said laser is Nd:

YAG laser.

12. The combination of claim 10, wherein said laser pulses of about 532 nm light at a duration of about 5 ns.

13. The combination of claim 10, wherein said optical fiber has a diameter ranging from about 0.1 mm to about 1.0 mm.

14. The combination of claim 10, wherein said short duration pulse is about less than 100 ns, and wherein said energy pulses are a wavelength of 200-3500 nm.

16. The method of claim 15, additionally including providing an acoustic lens for focusing or shaping the acoustic waves.

17. The method of claim 16, additionally providing the acoustic lens with means for converting compressive stress waves into a tensile stress waves.

18. The method of claim 15, wherein providing a source of laser radiation is carried out by providing a laser having a pulse duration of about less than 100 ns.

19. The method of claim 18, additionally including providing a laser having an energy density of about 0.1 to 100 J/g.

20. The method of claim 15, additionally including providing the absorber from material selected from the groups consisting of dyes, and opaque materials.

28. The device of claim 6 wherein said absorber is composed of a fluid that is circulated through the transducer.

29. The method of claim 15, wherein the acoustic wave is directed onto a calculus for the purpose of lithotripsy.

15. A method for producing acoustic waves by absorbed laser radiation, comprising:

providing a source of laser radiation,

providing an optical fiber,

providing a transducer containing an absorber, and

directing laser radiation through the optical fiber and onto the absorber for producing acoustic waves.

21. A device for converting laser radiation into acoustic energy, comprising;

an optical fiber for transmitting laser radiation,

a transducer mounted to a distal end of said optical fiber, and an absorber contained in said transducer and located adjacent said distal end of said optical fiber.

22. The device of claim 21, additionally including acoustic lens.

23. The device of claim 22, wherein said acoustic lens includes means for converting compressive stress waves into a tensile stress wave.

24. The device of claim 22, wherein said acoustic lens is mounted to said transducer.

25. The device of claim 22, wherein said acoustic lens is formed in said transducer.

26. The device of claim 21, wherein said absorber is composed of material selected from the group consisting of dyes and opaque materials.

27. A device, comprising:

an optical fiber adapted to transmit laser energy,

whereby laser energy transmitted through said optical fiber is directed into ambient absorbing material to produce acoustic wave for material destruction,

wherein distal end of said optical fiber is shaped so as focus the acoustic wave at a distance from said fiber tip.