Patent Publication Number: US-2015088105-A1

Title: Medical system for treating deep surface targets

Description:
TECHNICAL FIELD 
     The present invention relates to novel laser-based medical systems and methods, and more particularly to such systems and methods to treat deep surface tissue structures associated with with certain disorders using multiple laser beams. 
     BACKGROUND ART 
     Laser/tissue interactions and therapeutic applications of laser light are two rapidly growing areas of research. As is well known to those skilled in the art, high intensity laser beams have the potential to destroy bodily tissue, a property that can be turned to useful purposes in the field of the treatment of certain disorders. Some of these disorders involve unwanted cell structures that can be found in deep surface tissues. 
     However, structures and tissues that are buried deep within healthy tissue pose a special problem for laser-based methods if used for a transcutaneous treatment. More particularly, as lasers are ultimately just coherent light sources, any attempt to “illuminate” a buried structure in the deep surface tissues with laser light must necessarily also illuminate the tissue that lies between the laser source at the surface and the target structure. Thus, the heat from a laser that is directed at a buried target has the potential to destroy not only the structure, but also to the tissue that encloses it, in particular the skin surface. 
     Therefore, the use of lasers in medicine or similar fields is limited by several factors; one is the penetration depth for controlled or significant energies. The overall limitation in getting to deeper transcutaneous targets (such as deep dermis, fat, tendons, etc., without burning the skin the same time), is the fact that the absorbed energy/temperature is reduced exponentially the deeper the laser radiation gets (Lambert-Beer&#39;s law). This means that most of the light energy is absorbed at the surface of the skin. The intensity reduces quickly the deeper the laser penetrates. 
     Furthermore, the transcutaneous treatment of deep surface tissue structures such as tumors can induce an excessive degree of trauma to the skin, such as a burning of the skin surface, leading to necrosis and scarring. 
     Some of the currently available methods and systems have attempted to overcome these negative effects by including a complex cooling system to cool down the skin, in an attempt to reduce excessive heat development at the surface of the skin and the resulting trauma to the epidermal layer of the skin. However, such cooling systems add complexity to implementation, often requires that laser power be increased, and also may not provide a desired or uniform level of cooling and trauma reduction in the skin. The combination of non-uniformity in cooling and increased laser power can put the skin at an even greater risk of damage. Also, adjusting the fluence (energy/area) delivered by a laser, as specified by current procedures, generally provides an inadequate level of control and often leads to either over-treatment or under-treatment. Over-treatment may cause scarring, and under-treatment may result in no observable improvement in the condition being treated. 
     U.S. Pat. No. 5,746,738 discloses a medical system for the transcutaneous treatment of a target structure by laser light, comprising a laser beam delivery system producing a plurality of laser beams for simultaneously or alternately irradiating the target structure from multiple directions via the skin surface, wherein the laser beams individually are individually adjusted to have an energy level insufficient to ablate and/or burn the skin. However, the disclosed systems to not reduce or resolve the aforementioned issues. 
     Therefore, effective and improved systems and methods that are able to transcutaneous treat unwanted structures in deep surface tissues are needed. 
     DISCLOSURE OF INVENTION 
     In a first aspect, embodiments of the invention provide medical systems for the transcutaneous treatment of a deep tissue target structure by laser light. A laser beam delivery system produces a plurality of laser beams for simultaneously or alternately irradiating the target structure from multiple directions via the skin surface. Suitably, the laser beams are individually adjusted to have an energy level insufficient to ablate and/or burn the skin. The target structure comprises a deep tissue target structure. The laser beams have a combined energy level at their point of intersection to achieve a preselected thermal gradient sufficient to treat the deep tissue target structure. The medical system further comprises a cooling device for cooling the skin surface during irradiation. 
     The deep tissue target structure may be selected from the group consisting of collagen fibers, septal fibers, hair, blood vessels, nerves, glandular tissue of any type, superficial or deep fascia, nucleus pulposus, joints, cartilage, bone, water, fat, sweat glands, sebaceous glands, bacteria, varicose veins and tumor cells. 
     The deep tissue target structure may correlate with a disorder selected from the group consisting of cellulite, hyperhidrosis, cancer, backpain, acne, tumors, hypertrichosis, adipose tissue, skin irregularities, skin tightening and eye disorder. 
     Preferably, the laser beam delivery system comprises multiple lasers. 
     The laser beam delivery system may comprise one laser that uses mirrors or rotating or scanners or other devices to direct the beams from different directions/angles towards the deep tissue target structure. 
     In embodiments, each laser beam may be continuous or pulsed. 
     The laser beams may be produced at the same time or alternated or repeated to achieve the preselected thermal gradient at the deep tissue target structure. 
     In still another aspect, embodiments of the invention provide methods for the transcutaneous treatment of a deep tissue target structure in a patient comprising the steps of simultaneously or alternately irradiating the deep tissue target structure with a plurality of laser beams from multiple directions via the skin surface. The laser beams individually have an energy level insufficient to ablate and/or burn the skin. The target structure comprises a deep tissue target structure. The laser beams have a combined energy level at their point of intersection to achieve a preselected thermal gradient sufficient to treat the deep tissue target structure. The method further comprises cooling the skin surface during the irradiation. 
     The deep tissue target structure may be selected from the group consisting of collagen fibers, septal fibers, hair, blood vessels, nerves, glandular tissue of any type, superficial or deep fascia, nucleus pulposus, joints, cartilage, bone, water, fat, sweat glands, sebaceous glands, bacteria, varicose veins and tumor cells. 
     The deep tissue target structure may correlates with a disorder selected from the group consisting of cellulite, hyperhidrosis, cancer, backpain, acne, tumors, hypertrichosis, adipose tissue, skin irregularities, skin tightening and eye disorder. 
     Preferably, the plurality of laser beams are produced by multiple lasers. 
     In one embodiment, the plurality of laser beams are produced by one laser that uses mirrors or rotating or scanners or other devices to direct the beams from different directions/angles towards the deep tissue target structure. 
     In embodiments, each laser beam is continuous or pulsed. 
     The laser beams may be produced at the same time or alternated or repeated to achieve the selected thermal gradient at the deep tissue target structure. 
     In a further aspect, embodiments of the invention relate to the uses of a medical system according to the present disclosure for the treatment of a deep tissue target structure and/or for the treatment of a disorder selected from the group consisting of cellulite, hyperhidrosis, cancer, backpain, acne, tumors, hypertrichosis, adipose tissue, skin irregularities, skin tightening and eye disorder. More particularly, in a further aspect, embodiments of the invention relate to the use of the medical system according to any one of claims  1  to  7  of the appended claims for the treatment of a deep tissue target structure. 
     According to embodiments, the use may involve the deep tissue target structure being disrupted, ablated, coagulated, heated, emulgated and/or liquefied. 
     According to embodiments, the deep tissue target structure is selected from the group consisting of collagen fibers, septal fibers, hair, blood vessels, nerves, glandular tissue of any type, superficial or deep fascia, nucleus pulposus, joints, cartilage, bone, water, fat, sweat glands, sebaceous glands, bacteria, varicose veins and tumor cells. 
     The technology disclosed herein relates to a medical system, and corresponding methods and uses, comprising the novel use of lasers to treat tissue. An advantage of the present invention is that this is done in a manner so as to transfer a desired amounts of energy to deeper tissues, such as deep dermis, fat, deep vessels, fascia, tumors and others, without burning the skin, in particular the skin surface. 
     A laser focusing system for transcutaneous treatment has been developed that allows for a plurality of laser beams to intersect at a single focal point within a patient. A further advantage of the invention is that, collectively, the beams have enough energy to treat tissue or unwanted structures in the tissue at the focal point without burning and/or ablating the skin, in particular the skin surface. 
     A further advantage of the invention is that each individual laser beam will not by itself damage tissue, in particular the skin surface tissue. The use of several relatively low-powered lasers that treat tissue only when collectively directed to a single target has inherent safety features. For example, a single laser having a high energy level could not be used for the treatment of deep surface target structures since it would burn the upper layers of the skin by the high thermal gradient caused by the high energy level. 
     A further advantage of the invention is that it avoids or substantially reduces the prior limitation—in getting to deeper transcutaneous targets, such as deep dermis, fat, tendons, etc., due the fact that the absorbed energy/temperature is reduced exponentially the deeper the laser gets (Lambert-Beer&#39;s law)—without burning the skin the same time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates schematically a medical system for the transcutaneous treatment of tissue, according to an embodiment of the invention; 
         FIG. 2  shows the function of the medical system of  FIG. 1 , in use; 
         FIG. 3  (PRIOR ART) is a diagram showing the effect of the use of a traditional laser system in correlation with the penetration depth, for transcutaneous treatment; and 
         FIG. 4  is a diagram illustrating the effect of the use of a medical laser system according to an embodiment of the present invention, in correlation with the penetration depth, for transcutaneous treatment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Unless indicated otherwise herein, individual system design features, combinations of components, method steps or other techniques disclosed herein may be combined, in accordance with embodiments of the present invention, with any or all other system design features, combinations of components, method steps or other techniques disclosed herein. 
       FIG. 1  illustrates schematically a medical system  10  for the transcutaneous treatment of tissue, according to an embodiment of the invention. 
     A plurality (here  4 ) of laser devices  12 ,  14 ,  16 ,  18  are mounted (e.g. above a patient for treatment thereof), on a housing or frame schematically illustrated at  20 . Collectively, hereinafter these are referred to as a laser beam delivery system  21 . 
     As also indicated in relation to laser device  12 , this comprises a laser source  30  and focusing optics  32 . The construction of the other laser devices is preferably the same, but may be different to suit different treatments. 
     The laser devices  12 ,  14 ,  16 ,  18  emit respectively laser beams  1   a,    1   b,    1   c,    1   d,  for treatment of tissue, as discussed below. 
     In accordance with embodiments of the invention, a variety of types of lasers  12 ,  14 ,  16 ,  18  may be used, e.g., He:Ne, Nd:YAG, Er:YAG and others. The power level, the pulse duration, the frequency of the pulses, and the distance from the tip of the laser  12 ,  14 ,  16 ,  18  to the point where the laser beams converge, can be varied. 
     The laser beam delivery system  21  preferably comprises multiple lasers  12 ,  14 ,  16 ,  18  providing the plurality of laser beams  1   a,    1   b,    1   c,    1   d;  and there may be two, three, four or more beams. In another embodiment, the laser beam delivery system  21  comprises one laser  12 ,  14 ,  16 ,  18  that uses mirrors or rotating or scanners or other devices to direct the beams  1   a,    1   b,    1   c,    1   d  from different directions/angles towards the target. According to embodiments of the present invention, each laser beam  1   a,    1   b,    1   c,    1   d  produced by the laser beam delivery system  21  may be continuous or pulsed. 
     In one embodiment, the laser beams  1   a,    1   b,    1   c,    1   d  are produced at the same time, in another embodiment the laser beams  1   a,    1   b,    1   c,    1   d  are produced alternated or repeated to achieve the preselected thermal gradient at the deep tissue target structure. Alternatively, the laser beam delivery system  21  may include two or more different types of laser light sources  30  to provide a variety of different wavelengths or wavelength ranges. Optical beams  1   a,    1   b,    1   c,    1   d  from different laser light sources  30  may be directed to the targeted structure on a one-by-one basis or at the same time. 
     As mentioned above, examples of laser light sources  30  include, but are not limited to, diode lasers, diode-pumped solid state lasers, Er:YAG lasers, Nd:YAG lasers, argon-ion lasers, He-Ne lasers, carbon dioxide lasers, eximer lasers, ruby lasers, and so forth. For certain embodiments, a laser light source  30  is desirably a diode laser, such as an infrared diode laser. However, it should be recognized that the selection of a particular type of laser light source  30  in the laser beam delivery system is dependent on the types of the target structure and the type of the deep surface tissue to be treated using the medical system according to the present invention. The laser beam delivery system  21  may include one particular type of laser light source  30  capable of providing one wavelength or wavelength range. 
     The lasers  12 ,  14 ,  16 ,  18  are suitably mounted on axles  22 ,  24 ,  26 ,  28 , and are preferably rotatable by motors (not shown), e.g. stepper motors. As indicated in relation to laser  12 , operation of the motors enables the angular orientation (θ; with respect to the vertical) of the laser  12  to be adjusted, so as to adjust the direction of the laser beam  1   a  emanating therefrom. Adjustment of the other lasers  14 ,  16 ,  18  is achieved similarly. 
     The spatial position of the frame  20 , and therefore of the lasers  12 ,  14 ,  16 ,  18  is adjusted by positioning mechanism  34 , which is schematically illustrated for the present purposes. It will be appreciated by persons skilled in the art that positioning mechanism  34  may comprise a number of arms, links, axles, hinges, motors, gears and the like, in order to move the frame through space for optimal positioning of the lasers  12 ,  14 ,  16 ,  18  in relation to the tissue (not shown) to be treated. In particular, the positioning mechanism  34  is at least adapted for moving the frame  20  for vertical positioning in the y direction in  FIG. 1 , but is preferably adapted to move in the x, y and z directions. 
     The operation of the system  10  is controlled by processor-based control system  36 , which suitably includes user input and graphical user interface devices (not shown) to assist a practitioner in deploying treatment. In use, the control system  36  sends control signals to and receives (position) signals from positioning mechanism  34  via lines  38 . In addition, control system  36  sends control signals to lasers  12 ,  14 ,  16 ,  18  via lines  40 . 
     In embodiments, the control system  36  is electronically coupled to the laser beam delivery system  21  via any wire or wireless transmission channel and functions to control operation of the laser beam delivery system  21 , including the laser sources  30 , focusing element, or both. By way of example, the control system  36  can activate one or more laser light sources  30  of the laser beam delivery system as well as control a variety of optical parameters associated with an activated laser light source  30 . As another example, the control system  36  can control focusing elements  32  to control or adjust a pattern of optical energy that is directed to the targeted structure. 
       FIG. 2  shows the principle of the medical system of  FIG. 1 , in use. Each of the laser beams ( 1   a,    1   b,    1   c,    1   d ) is delivering low energy irradiation to the target structure  5  in a deep tissue  4  via the skin surface  2 . Examples of the deep tissue target structure  5  are collagen fibers, septal fibers, hair, blood vessels, nerves, glandular tissue of any type, superficial or deep fascia, nucleus pulposus, joints, cartilage, bone, water, fat, sweat glands, sebaceous glands, bacteria, varicose veins and tumor cells. 
     Examples for disorders correlating with the unwanted deep tissue target structures are cellulite, hyperhidrosis, cancer, backpain, acne, tumors, hypertrichosis, adipose tissue, skin irregularities, skin tightening and eye disorder. 
     To protect the skin surface  2  and to reach even deeper targets  5  the skin surface  2  is cooled by contact cooling (e.g. using a heat exchanger or heat sink) or the use of cryogenic or other techniques; in particular, the skin surface  2  make be cooled with a cooling device such as a contact pat or a cryogen spray (in each case, not shown). 
     Collectively, the beams  1   a,    1   b,    1   c,    1   d  have enough energy to treat the deep tissue target structure  5  at their focal point (intersection). However, each individual laser beam  1   a,    1   b,    1   c,    1   d  will not by itself damage tissue above the intersection of the laser beams  1   a,    1   b,    1   c,    1   d.  The use of several relatively low-powered lasers  12 - 18  to treat deep surface tissue only when collectively directed to a single target  5  has inherent safety features. 
       FIG. 3  (PRIOR ART) is a diagram showing the effect of the use of a traditional laser system in correlation with the penetration depth for transcutaneous treatment. The normalized power value of radiation incident upon tissue falls away exponentially with depth of penetration into the tissue. 
       FIG. 4  is a diagram illustrating the effect of the use of a medical laser system according to the present embodiment of the invention in correlation with the penetration depth for transcutaneous treatment. The effect of the use of multiple lasers focused upon the same point/area is that power is maximum (P M ) at depth d m , whereas, for example, a usable operational range may be available between d I  and d u , corresponding to power P O . The control system  36  may operate in use to keep the laser beam delivery system  21  operating between P O  and P M , and/or to adjust d I , d m  and d u . Preferably, the depth range d I  to d u  lies within the depth range of the target structure  5  at that (x, z) location. 
     Due to the cooling of the skin surface for example by a cooling device such as a contact cooling pat or a cryogen spray, the overlaying tissue like the skin surface is not burned and/or ablated. In an advantageous embodiment, no deeper than a second degree burn is produced on the skin, in particular on the skin surface, and preferably no deeper than a first degree burn. 
     In advantageous embodiments the medical system  10  according to the present disclosure comprises a laser beam delivery system  21  for producing multiple deep laser beams  1   a,    1   b,    1   c,    1   d  that are directed from multiple directions through the skin  2  towards the target  5  like a deep surface tissue or a deep surface tissue structure. In an advantageous embodiment, the laser beams  1   a,    1   b,    1   c,    1   d  are focused laser beams. 
     Surprisingly it was found that the energies the beams  1   a,    1   b,    1   c,    1   d  adds up to a higher overall energy, to achieve the desired aim of treating the target  5 , reach a thermal gradient, to disrupt, ablate, coagulate, heat, emulgate, liquefy, etc.; but due to the cooling and the use of a plurality of laser beams  1   a,    1   b,    1   c,    1   d,  the upper skin  2  is not damaged (burned or ablated). According to embodiments of the present invention, the cooling of the skin surface  2  allows the practitioner to treat very deep surface tissue structures  5 , as higher energy laser beams  1   a,    1   b,    1   c,    1   d  may be used. 
     Further embodiments of the present disclosure pertains to methods for the transcutaneous treatment of a deep tissue target structure in a patient comprising the steps of simultaneously or alternately irradiating the deep tissue target structure with a plurality of laser beams from multiple directions via the skin surface, wherein the laser beams individually have an energy level insufficient to ablate and/or burn the skin, and the laser beams have a combined energy level at the point of intersection to achieve a thermal gradient sufficient to treat the deep tissue target structure, and wherein the skin surface is cooled during the irradiation. 
     Furthermore, some embodiments relates to uses of the medical system according to the present disclosure for the treatment of a deep tissue target structure. 
     In accordance with the methods and uses, by selecting the appropriate laser wave length, wattage, pulse rate, the distance from each laser source  30  to the point of intersection, and the number of lasers  12 - 18 , the effect on body tissue can be carefully and precisely controlled. 
     The following example is offered for illustrative purpose only, and is not intended to limit the scope of the present disclosure in any way. 
     EXAMPLES  
     In the following, an example of the present disclosure is provided showing the improved treatment of deep-surface target structures  5  when using a medical system  10  according to the present invention. It should be understood that this example is for illustrative purpose only and is not to be construed as limiting this disclosure in any manner. 
     Example 1 
     Three 1064 nm long pulse lasers  12 - 16  were implemented in a treatment of fresh cadaver tissue. Subclinical fluence settings were used. 
     A thermometer was placed at 3 mm depth, and in a second study in 5 mm depth. Firing of a single 1064 nm laser with a subclinical fluence did not raise the temperature at 3 mm depth significantly. At 5 mm depth, no temperature change could be observed. 
     Firing the three 1064 nm lasers  12 - 16  from different angles, using surface cooling, and aiming all beams  1   a - 1   c  at one spot at 3 mm depth produced a significant observable rise in the temperature at that spot. 
     Histology with Azan staining (see Mallory F B (1900)  A contribution to staining methods. Journal of Experimental Medicine  5: 15-20) of that area showed no damage to superficial structures such as epidermis or superficial dermis. In the deep dermis—approx. 3 mm deep—denatured collagen could be seen. 
     In another procedure, the three beams  1   a - 1   c  were aimed at 5 mm depth. The same laser energies were fired; and a significant change of the temperature was observed. 
     Histology did not show significant changes. 
     Further embodiments of the invention will be apparent to persons skilled in the art. 
     In an advantageous embodiment, the medical system  10  includes an optical delivery system such as a laser beam delivery system, which includes an optical source, in particular a laser or a laser diode. The optical source functions to provide optical energy that can be directed to a deep surface target structure, such as a tumor. In some embodiments, the optical source provides optical energy in the form of one or more optical beams, in particular laser beams, which can be pulsed or continuous wave and coherent or incoherent. 
     In certain embodiments, the optical source may be implemented, at least in part, using one or more light sources, such as laser light sources. For certain applications, the optical source desirably includes multiple laser light sources, which can be arranged in an array, such as a one-dimensional array or a two-dimensional array. A laser light source can provide one or more optical beams having particular optical parameters, such as optical fluence, power, timing, pulse duration, inter-pulse duration, wavelength (s), and so forth, to produce a desired treatment effect for the targeted structure. By way of example, a laser light source can provide an optical beam having a wavelength or range of wavelengths between approximately 200 nm and 20,000 nm, such as between approximately 600 nm and 4000 nm. 
     In an advantageous embodiment, the laser beam delivery system may also include a focusing element that is optically coupled to the laser(s). The focusing element functions to direct optical energy from the laser to the targeted structure. In one embodiment, the focusing element directs optical energy to the targeted structure by focusing the power of the optical energy to one or more deep surface tissue target structure. 
     Use of a pattern of optical energy also can facilitate multiple treatments that may be needed to produce a full desired effect by allowing an individual treatment to be milder and with lower risk to a patient. Furthermore, visible impressions of treatment can be reduced by using a pattern of treatment where an individual treatment zone is on the same or smaller scale than the normal visible texture or constituents of the skin itself. 
     The present invention has now been described in accordance with several exemplary embodiments, which are intended to be illustrative in all aspects, rather than restrictive. Thus, the present invention is capable of many variations in detailed implementation, which may be derived from the description contained herein by a person of ordinary skill in the art. All such variations are considered to be within the scope and spirit of the present invention as defined by the following claims and their legal equivalents. 
     Example 2 
     Three 1064 nm long pulse lasers were implemented in a treatment of fresh cadaver tissue. Subclinical fluence settings werde used. 
     A thermometer was placed in 3 mm and in a second study in 5 mm depth. Firing of a single 1064 nm laser with a subclinical fluence did not rise the temperature in 3 mm depth significantly. In 5 mm depth no temperature change could be noticed. 
     Firing the three 1064 nm lasers from different angles, using surface cooling, aiming all beams on one spot in 3 mm depth showed a significant rise of the temperature in that spot. 
     Histology with Azan staining (see Mallory F B (1900) A contribution to staining methods. Journal of Experimental Medicine 5: 15-20) of that area showed no damage to superficial structures as epidermis or superficial dermis. In the deep dermis, approx. 3 mm deep, denatured collagen could be seen. 
     In another setting, the three beams were aimed at 5 mm depth. The same energies were fired; a significant change of the temperature was noticed. 
     Histology did not show significant changes.