Tissue cooling rod for laser surgery

Abstract

A laser treatment device and process with controlled cooling. The device contains a cooling element with high heat conduction properties, which is transparent to the laser beam. A surface of the cooling element is held in contact with the tissue being treated while at least one other surface of the cooling element is cooled by the evaporation of a cryogenic fluid. The cooling is coordinated with the application of the laser beam so as to control the temperatures of all affected layers of tissues. In a preferred embodiment useful for removal of wrinkles and spider veins, the cooling element is a sapphire plate. A cryogenic spray cools the top surface of the plate and the bottom surface of the plate is in contact with the skin. In preferred embodiments the wavelength of the laser beam is chosen so that absorption in targeted tissue is low enough so that substantial absorption occurs throughout the targeted tissue. In a preferred embodiment for treating large spider veins with diameters in the range of 1.5 mm, Applicants use an Er:Glass laser with a wavelength of 1.54 microns.

1. A laser system for tissue treatment, comprising:
 A) A hand-held portable battery powered tissue cooling unit comprising:
 1) a cooling transmitting element comprised of material transparaent transparent to light at a nominal wavelength and having high thermal conductivity and having a contact surface for contacting a surface of tissue being treated, 
 2) a cryogenic container mounted within or on said cooling unit, 
 3) a cryogen contained in said container, 
 4) a cryogenic cooling chamber for cooling at least one surface of said cooling element, said chamber having an entrance port communicating with said container and an exit port, 
 5) a battery powered cryogenic control means for permitting a flow of vaporizing cryogen from said container into said chamber to cool said at least one surface in order to remove heat from said tissue surface and to produce desired temperature distribution in target tissue being treated, and 
 6) a battery mounted on or within said cooling unit for providing power to said control means, and 
 
 B) a source of laser light defining a nominal wavelength arranged to transmit said laser light through said cooling transmitting element. 
 
     
     
       2. A laser system as in  claim 1  and further comprising a temperature-monitoring element mounted adjacent to but insulated from said contact surface for monitoring tissue surface temperature. 
     
     
       3. A laser system as in  claim 1  and further comprising a temperature-monitoring element configured to monitor temperature of said cooling element. 
     
     
       4. A laser system as in  claim 1  and further comprising a processor programmed for controlling said source of laser light and said flow of cryogen. 
     
     
       5. A laser system as in  claim 1  wherein said source of laser light is a free running mode Er:Glass pulse laser. 
     
     
       6. A laser system as in  claim 1  wherein said source of laser light is a Nd:YAG laser. 
     
     
       7. A laser system as in  claim 6  wherein said Nd:YAG laser is arranged to operate at a pulse width of about 50 ms. 
     
     
       8. A laser system as in  claim 6  wherein said Nd:YAG laser is arranged to operate at a pulse width of about 100 to 200 ms. 
     
     
       9. A laser system as in  claim 1  wherein said cooling transmitting element is sapphire plate and substantially all cooling of said plate is through a single non-circumferential surface. 
     
     
       10. A laser system as in  claim 1  wherein said cooling transmitting element is sapphire rod defining a circumferential surface and substantially all cooling is through said circumferential surface. 
     
     
       11. A laser system as in  claim 1  wherein said cooling transmitting element is a diamond plate. 
     
     
       12. A laser system as in  claim 1  wherein said cooling transmitting element is a diamond rod. 
     
     
       13. A laser system as in  claim 1  wherein said cooling transmitting element is a patterned rod. 
     
     
       14. A laser system as in  claim 1  wherein said cooling transmitting element has a concave form for self-collimating beam properties. 
     
     
       15. A laser system as in  claim 1  wherein said cooling transmitting element is a cylindrical rod mounted horizontally. 
     
     
       16. A process for treating tissue, comprising the steps of:
 A) generating from a source a laser light defining a nominal wavelength, 
 B) transmitting said laser light through a hand-held portable battery operated tissue cooling unit comprising a cooling transmitting element comprised of material transparent to light at said nominal wavelength and having high thermal conductivity and having a contact surface for contacting a surface of tissue being treated, 
 C) inserting cryogen from a cryogenic container, mounted on or within said cooling unit, into a cryogenic cooling chamber for said cooling element, said chamber having an entrance port communicating with said container and an exit port, 
 
       wherein said inserting permits a flow of vaporizing cryogen from said container into said chamber to cool said cooling element in order to remove heat from the tissue surface and to produce desired temperature distribution in target tissue and wherein the battery is mounted on or within the cooling unit. 
     
     
       17. A process as in  claim 16 , further comprising the additional step of sliding said cooling element across surface of tissue while applying laser radiation through a portion of said cooling transmitting element so as to provide pre, during and post cooling of said tissue. 
     
     
       18. A process as in  claim 17 , further comprising the step of controlling said source of laser light and said flow of cryogen with a processor programmed with a control algorithm. 
     
     
       19. A process as in  claim 17 , wherein said method is for the purpose of treating spider veins. 
     
     
       20. A hand-held portable battery powered tissue cooling unit, useful for both cryogenic tissue treatment and for cooling tissue during laser treatment, comprising:
 A) a cooling transmitting element comprised of material transparent to light at a nominal wavelength and having high thermal conductivity and having a contact surface for contacting a surface of tissue being treated, 
 B) a cryogenic container mounted on or within said cooling unit, 
 C) a cryogen contained in said container, 
 D) a cryogenic cooling chamber for cooling at least one surface of said cooling element, said chamber having an entrance port communicating with said container and an exit port, 
 E) a battery powered cryogenic control means for permitting a flow of vaporizing cryogen from said container into said chamber to cool said at least one surface in order to remove heat from said tissue surface and to produce desired temperature distribution in target tissue being treated, and 
 F) a battery mounted on or within said cooling unit providing power to said control means. 
 
     
     
       21. A cooling unit as in  claim 20  wherein said cooling transmitting element is comprised of sapphire. 
     
     
       22. A cooling unit as in  claim 20  wherein said cooling transmitting element is comprised of diamond. 
     
     
       23. A cooling unit as in  claim 20  wherein said control means includes a temperature detector. 
     
     
       24. A cooling unit as in  claim 23  wherein said temperature detector is a thermocouple. 
     
     
       25. A cooling unit as in  claim 24  wherein said cryogenic container is a replaceable container. 
     
     
       26. A cooling unit as in  claim 25  wherein said control means comprises a microprocessor for providing a controlled spray from said cryogenic container. 
     
     
       27. A cooling unit as in  claim 26  wherein said cooling transmitting element comprises a sapphire plate and wherein said microprocessor is programmed to provide a controlled spray from said cryogen container onto said sapphire plate. 
     
     
       28. A cooling unit as in  claim 27  wherein said cryogen is tetrafluoethan tetrafluorethane. 
     
     
       29. A method of treating skin tissue, comprising:
 generating laser light at a wavelength that in skin tissue is primarily absorbed by water;   transmitting the laser light through a transparent material contained in a hand-held unit, placing the hand-held unit in contact with skin tissue; and   converting the laser light from a beam to an irradiation pattern such that a portion of the laser light irradiates and damages a first tissue portion, a second portion of the laser light substantially simultaneously irradiates and damages a second tissue portion, and a portion of tissue between the first and second tissue portions is undamaged by the laser light.   
     
     
       30. The method of claim 29 wherein the step of converting the laser light from a beam to an irradiation pattern comprises masking the laser light. 
     
     
       31. The method of claim 29 further comprising cooling the transparent material, and placing the cooled transparent material in contact with the skin tissue during irradiation of the skin tissue by the laser light. 
     
     
       32. The method of claim 29 further comprising cryogenically cooling the transparent material. 
     
     
       33. The method of claim 29 further comprising cooling the transparent material, and placing the cooled transparent material in contact with the skin tissue so as to provide pre-cooling, post-cooling, or both pre-cooling and post-cooling of the skin tissue. 
     
     
       34. The method of claim 29 wherein the transparent material cools the temperature of the skin tissue at a depth of 100 μm beneath the surface and the laser light heats the temperature of the skin tissue at a depth of 400 μm beneath the surface to above 70° C. 
     
     
       35. The method of claim 29 further comprising focusing the laser light beneath the surface of the skin tissue with a focusing element. 
     
     
       36. The method of claim 29 wherein the transparent material focuses the laser light. 
     
     
       37. The method of claim 29 wherein the transparent material is slid across the tissue. 
     
     
       38. The method of claim 29 further comprising measuring the temperature of the skin tissue with a temperature monitoring element. 
     
     
       39. The method of claim 29 further comprising using the laser light to treat wrinkles. 
     
     
       40. The method of claim 29 wherein the laser light is generated with an Er:Glass laser. 
     
     
       41. The method of claim 29 wherein the laser light is generated with a laser lasing at a wavelength of approximately 1.54 μm. 
     
     
       42. The method of claim 29 wherein the laser light is generated with a laser with a wavelength that is absorbed more strongly by blood than by tissue surrounding blood vessels. 
     
     
       43. The method of claim 29 wherein the laser light is generated with a pulse duration of about 50-200 ms. 
     
     
       44. The method of claim 29 wherein the hand-held unit converts the laser light from a beam to a regular irradiation pattern such that irradiation of the skin tissue causes a regular pattern of spots of damaged tissue with undamaged tissue between the spots of damaged tissue. 
     
     
       45. A method of treating wrinkles in skin tissue, comprising:
 generating laser light with an Er:Glass laser lasing at a wavelength of approximately 1.54 μm;   transmitting the laser light through a transparent material contained in a hand-held unit;   placing the transparent material in contact with the skin tissue;   converting the laser light from a beam to an irradiation pattern that irradiates substantially simultaneously and damages a pattern of spots of skin tissue, with undamaged tissue between the spots of damaged tissue; and   cooling the transparent material, and placing the cooled transparent material in contact with the skin tissue during irradiation of the skin tissue by the laser light.   
     
     
       46. The method of claim 45 wherein the hand-held unit converts the laser light from a beam to a regular irradiation pattern such that irradiation of the skin tissue causes a regular pattern of spots of damaged tissue with undamaged tissue between the spots of damaged tissue. 
     
     
       47. The method of claim 45 wherein:
 the step of generating laser light comprises the Er:Glass laser generating pulses of laser light;   transmitting the laser light through a fiber optic cable to the hand-held unit; and   the hand-held unit converting the laser light from the beam to a regular rectilinear irradiation pattern such that irradiation of the skin tissue causes a regular rectilinear pattern of spots of damaged tissue with undamaged tissue between the spots of damaged tissue.   
     
     
       48. The method of claim 47 further comprising:
 the step of generating laser light comprises the Er:Glass laser generating pulses of laser light at a pulse repetition rate of between approximately 0.5-1.0 Hz; and   placing the cooled transparent material in contact with the skin tissue before, during and after irradiation of the skin tissue by the laser light.