System and method for microablation of tissue

Abstract

The present invention generally relates to the field of laser treatment of tissue, and particularly, to a system and method for creating microablated channels in skin. The present invention is more particularly directed to treating subsurface tissue through the created channels.

1 . A laser system comprising:
 a laser source;   a laser emitting device coupled to the laser source and configured to apply laser pulses to tissue, the tissue comprising an epidermis region, a dermis region below the epidermis region, and a hypodermis region below the dermis region; and   a controller configured to control application of the laser pulses;   wherein the controller is configured to direct the laser emitting device to apply at least one ablative laser pulse at each of a plurality of sites within a treatment area of the tissue to ablate a channel at each of the plurality of sites, each of the ablated channels having a depth that extends at least into the dermis region of the tissue and a diameter that is smaller than the depth of the ablated channel;   wherein the controller is configured to determine the number of sites within the treatment area and a spatial location of each site within the treatment area such that at least a portion of tissue between the plurality of sites is not ablated;   wherein the controller is further configured to control characteristics of each laser pulse such that a duration of each pulse is shorter than a tissue thermal relaxation time.   
     
     
         2 . The laser system of  claim 1 , wherein the diameter of each of the ablated channels is less than about 250 μm. 
     
     
         3 . The laser system of  claim 1 , wherein the laser source is a carbon dioxide (CO2) laser. 
     
     
         4 . The laser system of  claim 1 , wherein each of the ablated channels has a depth that extends into the hypodermis region. 
     
     
         5 . The laser system of  claim 1 , wherein the controller is further configured to control characteristics of each laser pulse such that a profile of thermal damage adjacent to each ablated channel has a uniform width along the depth of the channel. 
     
     
         6 . The laser system of  claim 5 , wherein the width of the profile of thermal damage is less than approximately 300 μm. 
     
     
         7 . The laser system of  claim 1 , wherein each ablative laser pulse has a spot size between about 80 μm to about 150 μm. 
     
     
         8 . The laser system of  claim 1 , wherein the plurality of sites are a first plurality of sites and the controller is further configured to direct the laser emitting device to apply at least one ablative laser pulse at each of a second plurality of sites within the treatment area of the tissue to ablate a channel at each of the second plurality of sites such that the ablated channel at each of the second plurality of sites has a depth and width that is different from the depth and width of the ablated channel at each of the first plurality of sites. 
     
     
         9 . The laser system of  claim 8 , wherein the ablated channel at each of the second plurality of sites has a depth that is smaller than the depth of the ablated channel at each of the first plurality of sites; and
 wherein the ablated channel at each of the second plurality of sites has a diameter that is larger than the diameter of the ablated channel at each of the first plurality of sites.   
     
     
         10 . The laser system of  claim 1 , wherein the controller is configured to direct the laser emitting device to apply a plurality of ablative laser pulses at each of the plurality of sites such that the plurality of channels are ablated in sequence. 
     
     
         11 . The laser system of  claim 1 , wherein the controller is configured to direct the laser emitting device to apply a plurality of ablative laser pulses at each of the plurality of sites such that the plurality of channels are ablated approximately concurrently. 
     
     
         12 . The laser system of  claim 1 , wherein the controller is configured to direct the laser emitting device to apply at least one non-ablative laser pulse through the channels formed at the plurality of sites. 
     
     
         13 . The laser system of  claim 1 , wherein the controller is configured to control characteristics of each laser pulse such that each laser pulse has a uniform power distribution across its respective spot. 
     
     
         14 . A method of operating a laser device, the method comprising:
 determining how many channels are to be ablated in an area of tissue;   determining a depth and width of each channel such that the depth is sufficient to extend at least into a dermis region of the tissue and the width is smaller than the depth;   determining a location for each channel in the area of tissue such that each channel is separated from the other channels by portions of the tissue;   determining characteristics of ablative laser pulses such that a duration of each ablative pulse is shorter than a tissue thermal relaxation time; and   directing a laser emitting device to apply at least one ablative laser pulse to each of the determined locations based on the determined characteristics to ablate a channel having the determined depth and width at each of the determined locations.   
     
     
         15 . The method of  claim 14 , wherein determining characteristics of the ablative laser pulses comprises determining characteristics of the ablative laser pulses such that each ablative laser pulse has a uniform power distribution across its respective spot. 
     
     
         16 . The method of  claim 14 , wherein determining the width of each channel comprises determining a width that is less than about 250 μm. 
     
     
         17 . The method of  claim 14 , wherein determining the depth of each channel comprises determining a depth that is sufficient to extend into a hypodermis region of the tissue. 
     
     
         18 . The method of  claim 14 , wherein determining characteristics of the ablative laser pulses comprises determining characteristics of each ablative laser pulse such that a profile of thermal damage adjacent to each ablated channel has a uniform width along the depth of the channel. 
     
     
         19 . The method of  claim 14 , wherein determining characteristics of the ablative laser pulses comprises determining characteristics such that each ablative laser pulse has a spot size between about 80 μm to about 150 μm. 
     
     
         20 . The method of  claim 14 , wherein the ablated channels comprise a first plurality of channels, the method further comprising:
 determining a depth and width of each of a second plurality of additional channels such that the depth of each additional channel is shorter than the depth of each channel in the first plurality of channels and such that the width of each additional channel is larger than the width of each channel in the first plurality of channels;   determining a location in the area of tissue for each of the second plurality of additional channels; and   directing the laser emitting device to ablate an additional channel at each of the determined locations for the second plurality of additional channels.   
     
     
         21 . The method of  claim 14 , wherein directing the laser emitting device to apply at least one ablative laser pulse to each of the determined locations comprises directing the laser emitting device to sequentially apply a plurality of ablative laser pulses at each of the determined locations, one location after another. 
     
     
         22 . A laser system comprising:
 a carbon dioxide laser source;   a laser emitting device coupled to the laser source and configured to apply laser pulses to tissue, the tissue comprising an epidermis region, a dermis region below the epidermis region, and a hypodermis region below the dermis region; and   a controller configured to control application of the laser pulses;   wherein the controller is configured to direct the laser emitting device to apply at least one ablative laser pulse having a spot size between about 80 μm to about 150 μm at each of a plurality of sites within a treatment area of the tissue to ablate a channel that extends at least into the dermis region at each of the plurality of sites;   wherein the controller is configured to direct the laser emitting device to apply the at least one ablative laser pulse at each site in a pattern such that the channel ablated at each site is separated from the other channels by non-ablated tissue;   wherein the controller is further configured to control characteristics of each laser pulse such that each laser pulse has a uniform power distribution across its respective spot and such that a duration of each pulse is shorter than a tissue thermal relaxation time.