Laser system and method for treatment of biologic targets

• US 20040024390A1
• Filed: 07/31/2003
• Published: 02/05/2004
• Est. Priority Date: 04/09/1996
• Status: Active Grant

• Current Assignee: Cynosure Incorporated
• Original Assignee: Cynosure Incorporated
• Inventors: Furumoto, Horace W.
• Granted Patent: US 7,118,562 B2
• Time in Patent Office: Days
• US Class Current: 606/9
• CPC Class Codes: A61B 18/203 applying laser energy to the outside of the body
• CPC Class Codes: A61B 2017/00172 Pulse trains, bursts, intermittent continuous operation
• CPC Class Codes: A61B 2017/22085 light-absorbing A61B2017/22087 takes precedence
• CPC Class Codes: A61B 2018/00452 Skin
• CPC Class Codes: A61B 2018/00476 Hair follicles
• CPC Class Codes: H01S 2301/08 Generation of pulses with special temporal shape or frequency spectrum
• CPC Class Codes: H01S 3/08072 Thermal lensing or thermally induced birefringence; Compensation thereof
• CPC Class Codes: H01S 3/092 of flash lamp H01S3/0937 takes precedence ; flash lamps per se H01J61/80; circuit arrangements for operating flash lamps in general H05B41/30
• CPC Class Codes: H01S 3/1633 BeAl2O4, i.e. Chrysoberyl

Abstract

A long pulse alexandrite laser for treating dermatological specimens is disclosed. The use of alexandrite allows operation in the near-infrared, specifically in a 50 nm range surrounding 755. Infrared in this range allows good penetration while still achieving an acceptable ratio of hemoglobin to melanin absorption. In operation, the laser generates pulses having a durations between 5 and 100 msec and fluences between 10 and 50 J/cm². A light delivery system is provided that transmits the laser light output pulse to dermatological targets of a patient. The invention is also directed to a hair removal system. Here, it is desirable to use an index-matching application on the skin sections to be treated, and a visual indicator is thermo- or photo-responsive or otherwise responsive to the laser light pulse to generate a visible change. Also, the invention is directed to a combined sclerotherapy and light treatment method and kit for unwanted veins. Substantially increased success has been achieved by implementing a dwell time of between 12 hours and 6 months between the light-based therapy and the sclerotherapy. Finally, the invention relates to pulse periodic heating of biologic targets, including systems and methods for generating an effective light output pulse comprising a series of sub-pulses with a limited duty cycle and a periodicity that is less than the thermal relaxation time of the targeted structure.

Claims

1. A method for treating biologic tissue with pulse light, comprising:

generating a long effective output light pulse comprising a series of sub-pulses having a fractional duty cycle over a selected effective pulse duration, a periodicity that is less than the thermal relaxation time of a targeted structure, and an interpulse-delay between successive sub-pulses that is greater than the thermal relaxation time of non-targeted structures within the treatment area; and

delivering the output light to the tissue of a patient.

2. The method as described in claim 1 wherein the output light pulse comprises a laser light pulse.

3. The method as described in claim 1 wherein the effective pulse duration is approximately equal to the thermal relaxation time of the targeted structure.

4. The method as described in claim 1 wherein the targeted structure comprises blood vessels.

5. The method as described in claim 4 wherein the targeted blood vessels are larger than 30 microns in diameter.

6. The method as described in claim 1 wherein the effective pulse duration is larger than 0.1 msec.

7. The method as described in claim 1 wherein the effective pulse duration is larger than 0.5 msec.

8. The method as described in claim 1 wherein the effective pulse duration is larger than 5 msec.

9. The method as described in claim 1 wherein the effective pulse duration is larger than 50 msec.

10. The method as described in claim 1 wherein the non-targeted structures include normal-sized blood-vessels.

11. A system for treating biologic tissue, comprising:

a pulse light source for generating a long effective output light pulse comprising a series of sub-pulses having a fractional duty cycle over a selected effective pulse duration, a periodicity that is less than the thermal relaxation time of a targeted structure, and an interpulse-delay between successive sub-pulses that is greater than the thermal relaxation time of non-targeted structures within the treatment area; and

a light delivery system that transmits the pulse light to the tissue of the patient.

12. The system as described in claim 11 wherein the pulse light source is a laser.

13. The system as described in claim 12 wherein the laser is a dye laser.

14. The system as described in claim 12 wherein the laser is a gas discharge laser.

15. The system as described in claim 12 wherein the laser is a solid-state laser.

16. The system as described in claim 12 wherein the laser is an alexandrite laser.

17. The system as described in claim 12 wherein the laser is a ruby laser.

18. The system as described in claim 12 wherein the laser is an Nd:

YAG laser.

19. The system as described in claim 11 wherein the effective pulse duration is approximately equal to the thermal relaxation time of the targeted structure.

20. The system as described in claim 11 wherein the targeted structure comprises blood vessels.

21. The system as described in claim 20 wherein the targeted blood vessels are larger than 30 microns in diameter.

22. The system as described in claim 11 wherein the non-targeted structures include normal-sized blood-vessels.