Abstract:
Skin tissue is subjected to energy that creates differential heating of the area being treated causing pores and follicle ducts to open so that excess oil, sebum, fatty deposits, or other unwanted deposits can be removed. A vacuum device is used to direct suction to the treated skin area helping to remove the unwanted deposits. The heating is controlled so that no skin tissue is damaged while still providing enough heat to the sebaceous gland to alter the gland to reduce its production of sebum and destroy bacteria in the treated area.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of U.S. application Ser. No. 09/694,738 filed on Oct. 23, 2000 for Method and Apparatus For Permanent Hair Removal which is a continuation of U.S. application Ser. No. 09/132,537 filed on Aug. 11, 1998 for a Method For Permanent Hair Removal, now U.S. Pat. No. 6,168,590 granted Jan. 2, 2001 which claims the benefit of the filing date of U.S. Provisional Application Serial No. 60/055,577, filed on Aug. 12, 1997 for Method and Apparatus For Selective Hair Removal and Modification. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to the application of energy to biological tissue, and specifically to the application of electromagnetic energy to the skin in order to treat various skin diseases.  
         BACKGROUND OF THE INVENTION  
         [0003]    It is known in the art to apply electromagnetic energy to biological tissue to engender changes therein. Sunbathers, for example, regularly expose themselves to bright sunlight in order to increase melanocyte activity in the basal layer of the epidermis, responsive to the sun&#39;s ultraviolet (UV) radiation. Artificial UV sources have been created to satisfy the desire for a “healthy”-looking tan in the winter. Other forms of electromagnetic energy, laser-light in particular, are currently used in a large range of therapeutic and cosmetic procedures, including eye surgery, hair removal, wrinkle removal, and tattoo removal.  
           [0004]    PCT publication WO 98/55035, which is incorporated herein by reference, describes methods for minimizing injury to biological tissue surrounding a site exposed to pulses of electromagnetic energy.  
           [0005]    U.S. Pat. No. 5,720,894 to Neev et al., which is incorporated herein by reference, describes biological tissue processing using Ultrashort Pulse High Repetition Rate Laser System for Biological Tissue Processing.  
           [0006]    It is known in the art to use UV and blue light to cure acne. A beam of short wavelength light is irradiated and is supposed to destroy bacteria through sterilizing ability of the high energy photon to disrupt molecular bond and photochemical destruction of living cells. This method is deficient however, because of the relatively short depth of penetration of the short wavelengths regime and the danger of mutagenetic effect as well as the effective shielding of deeper lying bacteria by superficial skin structures.  
           [0007]    It is also known in the art to use chemical peels and Retin A to chemically peel of the outer layer of the skin. This method is deficient however, because of side effect, long response time and longer time duration between application of the treatment and results and various side effects.  
           [0008]    It is also known in the art to apply antibiotic to patients in order to combat active acne. This method is deficient however, since the application of antibiotic is non-selective, often done systemically and thus effect the entire body, and also for the fact that various organisms and bacteria develop resistance to antibiotics and in fact, expose the entire body to increase danger in exposure to bacteria that is now resistance to antibiotics.  
           [0009]    It is also known in the art to combat active acne by treating and controlling hormonal activity within a patient body. Again, this is a systemic approach that suffers from many side effects including, in some cases, severe depression, and impact on the entire body.  
           [0010]    It is therefore, desirable, to have a simple, non-invasive, non-systemic treatment method and apparatus for the treatment and cure of acne, that, when applied, are free of side effect, yet safe and effective. It is also desirable to have a method that is easy to apply and is relatively quick and easy to administer and produce rapid skin response, relief of symptoms, and cure for the condition.  
           [0011]    It is therefore, desirable, to have a simple, non-invasive, non-systemic treatment method and apparatus for the treatment and cure of other skin diseases and skin conditions, that, when applied, are free of side effect, yet safe and effective.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0012]    It is an object of some aspects of the present invention to provide improved apparatus and methods for applying energy to a material.  
           [0013]    It is another object of some aspects of the present invention to provide improved apparatus and methods for removing heat generated during application of electromagnetic energy to a material.  
           [0014]    It is a further object of some aspects of the present invention to provide improved apparatus and methods for removing heat generated during application of electromagnetic energy to biological tissue.  
           [0015]    It is still a further object of some aspects of the present invention to provide improved apparatus and methods for decreasing pain during application of electromagnetic energy to biological tissue.  
           [0016]    It is yet a further object of some aspects of the present invention to provide improved apparatus and methods for performing medical treatments.  
           [0017]    It is also an object of some aspects of the present invention to provide improved apparatus and methods for performing cosmetic treatments.  
           [0018]    It is also an object of some aspects of the present invention to provide improved apparatus and methods for healing of skin diseases and skin illnesses.  
           [0019]    It is further an object of some aspects of the present invention to provide improved apparatus and methods for enabling electromagnetic energy source to allow healing of skin diseases and skin illnesses or improved conditions.  
           [0020]    It is yet a further object of some aspects of the present invention to provide methods and apparatus for enabling a chemical, RF, Microwave, mechanical, electric, magnetic, or ultrasound energy to advance healing skin diseases and skin illnesses.  
           [0021]    It is also an object of some aspects of the present invention to provide improved methods and apparatus for enabling a low-power electromagnetic energy source to advance healing skin diseases and skin illnesses substantially without pain, while substantially minimizing the amount of damage or modification to remaining tissue.  
           [0022]    It is also an object of some aspects of the present invention to provide improved methods and apparatus for enabling a low-power electromagnetic energy source to perform skin treatment, treatment of acne and treatment that prevent the occurrence of acne.  
           [0023]    It is also an object of some aspects of the present invention to provide improved methods and apparatus for enabling a low-power electromagnetic energy source to perform tissue treatment that cures acne and relieves symptoms of acne.  
           [0024]    In a preferred embodiment of the present invention, the tissue of the skin is subjected to localized heating that for a given time and in a defined location, elevates the temperature of the skin in one location as compared to an its normal temperature. This elevation of skin temperature corresponds to expansion and displacement of a portion of the skin thus leading to opening of skin pores.  
           [0025]    In another preferred embodiment of the present invention, the tissue of the skin is subjected to localized heating that for a given time and in a defined location, elevates the temperature of the skin in one location as compared to an adjacent location. This elevation of skin temperature corresponds to expansion and displacement of a portion of the skin with respect to an adjacent location thus leading to opening of skin pores.  
           [0026]    In a further preferred embodiment, an intermediate substance which is capable of absorbing at least a portion of the electromagnetic energy from a source, is placed between the energy source and the skin, absorbs the source energy and converts it to heat. Being in contact with the skin, the substance elevates the temperature of the skin to cause to an expansion and displacement leading to opening of skin pores and relieving of acne conditions.  
           [0027]    In yet a further preferred embodiment, an intermediate substance which is capable of absorbing at least a portion of the electromagnetic energy from a source, is placed between the energy source and the skin, absorbs the source energy and converts it to heat. Being in contact with the skin, the substance elevates the temperature of the skin in one location as compared to an adjacent location. This elevation of skin temperature corresponds to expansion and displacement of a portion of the skin with respect to an adjacent location thus leading to opening of skin pores. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    [0028]FIG. 1 is a simplified diagram of an apparatus for treating skin in order to prevent and cure acne and other skin conditions in accordance with a preferred embodiment of the present invention;  
         [0029]    [0029]FIG. 2 is a simplified diagram of an apparatus for treating skin in order to prevent and cure acne and other skin conditions in accordance with a preferred embodiment of the present invention;  
         [0030]    [0030]FIG. 3 is a simplified diagram of an apparatus for treating skin in order to prevent and cure acne and other skin conditions in accordance with a preferred embodiment of the present invention;  
         [0031]    [0031]FIG. 4 is a simplified diagram of a method for treating skin in order to prevent and cure acne and other skin conditions in accordance with a preferred embodiment of the present invention;  
         [0032]    [0032]FIG. 5 is a graph of a temperature profile generated for treating skin in order to prevent and cure acne and other skin conditions in accordance with a preferred embodiment of the present invention;  
         [0033]    [0033]FIG. 6 is a schematic illustration of a preferred embodiment illustrating a device for treating skin according to the present invention; and  
         [0034]    [0034]FIG. 7 is a diagrametic illustration of a cross-section of skin temperature changes that occur in sections of the skin as the result of the present invention.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0035]    Referring first to FIG. 1 which illustrates a preferred embodiment that contemplates a device comprising an energy source  10 , capable of displacing a portion of the skin  20 , so that at least one skin pore  30  is forced to open so that excess oil, sebum, fatty deposits, or other unwanted deposits can be removed from the pore.  
         [0036]    [0036]FIG. 2 illustrates another simplified diagram for treating acne and other skin conditions in accordance with a preferred embodiment of the present invention. Here, the energy source  10  is a source that emits a beam of electromagnetic energy  200  carrying particles (photons). The beam  200  of photons is then intercepted and absorbed by an intermediate material  210  which contains a substance capable of absorbing photons. The energy of the photons absorbed by the substance  210  is converted to heat which, in turn, is conducted to the skin  20 . The thermal energy thus deposited on the skin forces at least one skin pore  30  to open so that excess oil, sebum, fatty deposits, or other unwanted deposits can be removed from the pore.  
         [0037]    [0037]FIG. 3 illustrates another simplified diagram for treating acne. Here, the energy source  10  is a source that emits a beam of electromagnetic energy  200  carrying particles (photons). A substance  310  capable of absorbing the photons is applied to the skin. The energy of the photons impinging on the substance  310  is converted to heat energy which, in turn, is either partly conducted to the skin  20 , or results in ablative or evaporative explosive removal of the top layer of the skin. The thermal energy thus deposited on the skin forces at least one skin pore  30  to open so that excess oil, sebum, fatty deposits, or other unwanted deposits can be removed from the pore. If evaporation or ablation is achieved, opening of the pores may be accomplished, at least in part, by removal of material that is blocking the pore or hair duct openings at the surface of the skin. In a variation of this preferred embodiment, the substance  310 , capable of absorbing the photons is substantially removed from most of the skin prior to irradiation by the photon beam  200 , except that some of the high absorption substance  310  is left in and around the location of the pore or hair duct opening.  
         [0038]    A variation of this preferred embodiment includes a heat removal phase that causes rapid contraction. This phase follows the photon and heat phase. A source of coolant material  320  is caused to direct a coolant substance  330  to the area of the skin being treated.  
         [0039]    Another embodiment contemplates an energy source  10  which emits a beam of electromagnetic energy  200  carrying particles, i.e., photons. The beam of photons is focused into a spatial location  400  underneath the skin surface to achieve subsurface heating of layers inside the skin  20 . The energy of the photon is converted to heat energy in the skin  20 . The thermal energy in the skin forces at least one skin pore  30  to open so that excess oil, sebum, fatty deposits, or other unwanted deposition can be removed from the pore.  
         [0040]    A source of vacuum  340  may be used after this step. Vacuum source  340  will be activated following the heating and displacement phases to enhance the removal of unwanted substance from the skin. By applying a vacuum suction action  350  to the surface of the skin, the unwanted substance in the skin pore  30  or hair duct is removed.  
         [0041]    A variation of this preferred embodiment utilizes a heat removal and rapid contraction phase following the photon heat depositions when a substance capable of removing the energy from the skin is applied to the skin surface.  
         [0042]    In its most general form, the device contemplated by the present invention contains an energy source capable of modulating physical conditions of the skin by heating or mechanically modulating a portion of the skin to treat skin diseases and skin conditions. This embodiment may also include components to allow focusing the energy from the energy source  10  so that a portion of the skin  20  is displaced with respect to an adjacent portion of the skin. Such relative differential displacement may allow loosening of skin components that block efficient drainage of the pores and hair follicle openings to relieve acne and other undesirable skin conditions.  
         [0043]    The device contemplated by the present invention may contain an energy source capable of modulating skin physical conditions by heating wherein the heat is also capable of sterilizing an infected area underneath the skin surface thus improving skin conditions such as acne and curing skin diseases. In a further improvement, the heat is also capable of reaching deeper into the skin and changing the condition of the sebaceous gland so that they produce less sebum, or even no sebum, which is a long term advantage in eliminating acne problems.  
         [0044]    The energy source utilized may include, but is not limited to light energy, electromagnetic energy, laser energy, RF energy, microwave energy, ultrasound energy, mechanical energy, or chemical energy. Electromagnetic energy, RF energy, light energy, and microwave energy when absorbed in the skin tissue results in expansion and displacement of one portion of the skin with respect to the other. Temperature increases in the range of 15° C. to 250° C. achieve optimal results both in terms of displacement as well as in terms of sterilization impact on the uppermost layers of the skin.  
         [0045]    [0045]FIG. 5 shows the temperature generated with a device constructed in accordance with the present invention. It shows that temperatures as high as 70° C. and 80° C. can be generated.  Physical Properties of Tissue  by F. A. Duck shows that the thermal expansion coefficient of human fat is 19.9×10 4 /0° C. For a volume of a 100 micrometer cube, an increase in temperature on the order of from about 50° C. to about 100° C. will result in a thermal expansion ratio on the order of from about 20 micrometers to about 30 micrometers. Thus, if the skin undergoes a temperature increase of 50° C. to a depth of about 100 micrometers, one can expect a sebum driven expansion of about 20 micrometers. This is about one fourth the size of an average human hair follicle.  
         [0046]    Besides utilizing an energy source capable of modulating the physical conditions of the skin, the present invention contemplates using a vacuum source for applying suction to the surface of the skin following the energy deposition to enhance removal of unwanted substances from the skin.  
         [0047]    An energy source that delivers mechanical energy directly to the skin to effect displacement of the surface of the skin to allow opening and cleaning of skin pores and follicle openings may be used instead of thermal generating energy. Ultrasound energy generates thermal energy in the skin causing displacement in the skin and opening and cleaning the skin pores and follicle openings.  
         [0048]    If thermal energy is being applied to the skin, an intermediate element capable of conducting the thermal energy to the skin sufficient to open and clean skin pores and follicle openings is desirable. If electromagnetic energy is being used, the intermediate element should contain, at least in some portion, a substance that allows absorption of electromagnetic energy and converts it into heat.  
         [0049]    If the electromagnetic energy being used is in a spectral range that is absorbed well by the skin, localized heating of the skin and differential displacement of some of the skin volume can be accomplished by simply focusing the beam of electromagnetic energy directly on the skin.  
         [0050]    If the source of energy is laser energy, energy in the visible range of the spectrum can be used as generated, for example, from a solid state diode laser. The energy from the laser is directed to an intermediate substance capable of both absorbing the laser energy and transmitting the absorbed laser energy to the skin. The intermediate substance can be deposited on an intermediate medium, such as a film made of polymers or agar containing a substance that absorbs the laser energy. Alternatively, a thin paper medium containing a substance that absorbs the laser energy may be used.  
         [0051]    The intermediate medium is brought into contact with the skin and the laser is activated. The laser beam may be focused to a small spot to maximize power density. Spot size diameter can range from about 1 micrometer to about 10 mm and preferably is from about 100 micrometer to about 2 mm. A Continuous Wave (CW) solid state laser may be used as an energy source. The power may vary from about 1 mw to about 200 W, and preferably the range should be from about 0.2 W to 15 W. The tight focused spot may be moved around a targeted skin surface area using scanners so that a transient energy deposition occurs in each local spot with dwell time ranging from about 1 microsecond to as long as about 10 seconds, and preferably from about 1 ms to about 50 ms.  
         [0052]    [0052]FIG. 5 shows the range of temperatures that can be generated with a device contemplated by the present invention. For example, a CW solid state laser system of 1 W output power and 808 nm wavelength with a spot size of 200 micrometers in diameter and scanning over an area of 1 cm by 1 cm in about 2 seconds generates a fluence of about 2 Joule per square cm, with dwell time of about 1 ms. The temperatures that can be generated are on the order of 30° C. to 90° C., depending on the density of the laser energy absorbed by the absorbing material. The density of the absorbers may range form about 3% coverage of the intermediate material surface to as mach as about 100% coverage of the intermediate material, and preferably from about 30% to about 100% coverage of the intermediate material surface, with the substance being capable of high absorbence of the laser energy.  
         [0053]    A vacuum source is preferably also used to suction the smoke generated during the interaction, as well as to remove debris and unwanted material from the treated skin surface, the hair follicle opening, and skin pores.  
         [0054]    The intermediate absorbing material may contain a laser absorbing substance arranged in patterns that maximize the penetration of light to depths of between about 100 micrometers to about 1 mm in order to maximize penetration of the light to heat the sebaceous glands and minimize secretion of the sebum. The preferred density for deeper laser light penetration and direct light heating of the upper layers of the skin is between about 0% to about 70% and preferably (if surface heating utilizing the intermediate absorbing material is taken into account) between 3% and 50%. A laser in the blue to ultraviolet range may be used in order to utilize the sterilization effect of these wavelengths, as well as generating heat. The heat generation will be increased due to the increased absorption resulting from the shorter wavelengths. In addition, blue and green to orange wavelengths are more readily absorbed in the hemoglobin in the blood and thus enhance heat generation at the surface of the skin and in layers below the surface.  
         [0055]    It is preferable to use a focusing element to focus the energy from the energy source on a smaller region of the skin. For example, a focused spot may be as small as about 1 micrometer or as large as about 10 mm and preferably between about 10 micrometers and about 2 mm. Such a spot size will create localized heating that results in differential temperature between one spot on the skin surface and an adjacent spot. The expansion of the heated spot will force displacement and opening of the pores and hair follicle openings. The heating of the skin will also result in sterilization of bacteria and lowering the ability of the sebaceous gland to produce sebum. A scanner or other similar element may be use to move the focused beam across a larger treatment area (for example, a total treatment area from about 2 mm by 2 mm to about 10 cm by 10 cm and preferably from 4 mm by 4 mm to about 5 cm by 5 cm). Treatment time for this area should be from about 0.2 second to about 10 seconds, and preferably from about 0.5 second to about 5 seconds.  
         [0056]    A willfully triggered substance capable of removing thermal energy (cool air, coolant spray, cryogen spray, liquid nitrogen spray, or a jet Freon-like substance, for example) from the skin at a desired time is also desirable. The activation of the cooling substance to remove energy from the skin surface or the intermediate material surface can be applied before, during, or after the application of energy to the skin surface, but preferably is applied only during or after the application of energy to the surface.  
         [0057]    If the energy source used is microwave energy, it is applied to the surface of the skin to allow generation of heat and localized displacements in accordance with principles of the present invention.  
         [0058]    If the energy source used is electric energy, it is applied to the surface of the skin to allow generation of heat and localized displacements in accordance with the principle of the present invention. DC or alternating currents, for example, may be applied to the skin tissue and will result in localized heating in accordance with the principles of the present invention.  
         [0059]    If the energy source used by the device is plasma energy, the electrically charged electrons and ion gas that is the plasma carries significant energy that can be applied to the surface of the skin. This energy allows generation of heat and localized displacement as well as surface cell removal, and removal of unwanted deposits form the surface of the skin in accordance with principles of the present invention.  
         [0060]    If the energy source used by the device is chemical energy, the chemical energy can be applied to the surface of the skin to cause material removal and removal of unwanted deposits from the surface of the skin further allowing opening of skin pores and hair duct openings, in accordance with principles of the present invention. The chemical energy may also generate localized displacements in accordance with principles of the present invention.  
         [0061]    If the energy source used by the device is ultrasound energy, the ultrasound energy can be applied to the surface of the skin to cause surface spatial displacement as well as generation of heat in accordance with principles of the present invention.  
         [0062]    Forms of mechanical energy may also be applied to the skin to cause localized displacement of portions of the skin, thus leading to unplugging and opening of skin pores and hair follicles.  
         [0063]    In a preferred embodiment, the method of the present invention contemplates applying energy to the outer layer of the skin so that the temperature of the top layer of the skin, for example, the top 10 to 50 micrometers of the epidermis are raised to a temperature of between 100° C. to 200° C. above the normal skin temperature. Energy flux of 1 Joule/cm 2  would raise the temperature of a water-like substance (for example body cells) to a temperature of about 250° C., if heated to a depth of 10 micrometers. A laser source of 1 W scanned at a rate of 1 cm 2  per second will dwell on a beam spot of about 100 micrometers in diameter for about 0.1 ms. If the energy in our example is deposited at the surface of the skin, in this time duration, the heat will diffuse down to a depth of about 10 micrometers and with water-like material heat capacity of about 4.2 Joules/gram/°C., will cause the temperature rise to be about 250° C.  
         [0064]    One important element that is exploited by the present invention is value of the thermal coefficient expansion of fatty material which is about 200,000 per degree C for fat, but only about one tenth of this value in water or cells. Thus, in the top ten microns or so, the temperature rise is going to create an expansion ratio of about 30% to 40% in fat but only 4% in water. If a follicle opening about 100 micrometers in diameter is substantially filled with sebum, the sebum will expand to 30% over its original volume. Sufficient pressure is thus generated for opening of the follicles and skin pores.  
         [0065]    A 10 ms heat application will diffuse down to about 100 micrometers in a water-like material. For the same amount of energy input as described above (1 Joule/cm 2 ) the average temperature rise is only 25° C. However, even this temperature rise will result in about 4% volumetric thermal expansion in fatty tissue. Thus, significant expansion can be achieved even at these low levels.  
         [0066]    If the temperature rise of 100° C. to 200° C. occurs for a longer time duration or at a higher energy level, fusion of the collagen around the follicle could occur and worsen the blocking of the sebaceous gland drainage, actually aggravating the problem.  
         [0067]    For example, after 10 ms, heat deposited at the skin surface, will diffuse in water like tissue, to a depth of about 100 micrometers. The relationship DT=DE/C where C is the material specific heat in Joules/gram/° C., DT is the temperature rise in °C., and DE is the input energy to the volume being heated in Joules, is used. To achieve 100° C. throughout the exemplary follicle volume of 100 micrometer diameter to 100 micrometer depth, 4 Joules of energy are needed. Similarly, to achieve DT=60° C. about the thermal denaturation temperature of tissue, about 2 Joules of energy are needed. Such temperature rises in the lower epidermis or upper dermis may result in both patient discomfort and in clogging or even fusing of the collagen around the follicle creating permanent or longer lasting blockage of the follicle ducts and skin pores. Such a temperature impact may be beneficial however, by damaging the sebaceous glands thus reducing sebum production, but will not be helpful in treating immediate inflamed, or active acne.  
         [0068]    An example of parameters used in a device constructed according to the principle of the present invention are shown in the table below.  
                                               0.6 W = input power   Position   Time (Sec)   Fluence (J/cm 2 )                       3   3.5-12   2.1   Sebaceous gland modification           2   2.5   1.5   Used effectively           1   1.5   0.9   Used Effectively                  
 
         [0069]    A preferred embodiment of a device  685  for treating skin conditions is illustrated in FIG. 6.  
         [0070]    An energy source  610  is triggered by a signal from a control box  620  which contains a microprocessor  630 . The activation of the energy source sends a beam through a collimator  600  to two scanner mirrors  650  and a focusing lens  670 . The beam then impinges onto an intermediate material (for example the Opto-thermal converter) attachment  680  and a high absorbing substance film  690 . The Opto-thermal converter attachment and the high absorbing substance film are in physical contact with the patient&#39;s skin  695 .  
         [0071]    A typical energy source  610  would be a 1 W to 4 W infrared laser, for example, at 810 nm, with a spot size of between 2 micrometers and 2 millimeters. The beam is scanned with a dwell time of 0.1 ms and up to about 0.5 second to cover an area of about 10 mm×10 mm.  
         [0072]    The device  685  may also contain a source for a substance  615  capable of removing energy from the intermediate material  680 . The flow of the energy removal substance is directed towards the intermediate high absorbing substance film  690  by a tube  605 . The flow amount is controlled by an electronic valve  625  which is controlled by the microprocessor  630  in the control box  620 . The microprocessor synchronizes the triggering of the energy source  610 , the substance capable of energy removal  615 , and the two scanners  650  for moving the energy beam around.  
         [0073]    The control box  620  may further include a vacuum pump  635  capable of keeping the treatment area clean through an evacuation tube  655 . Alternatively, the vacuum pump  635  can be used to create vacuum suction at the skin for cleaning the skin surface, pores and follicle openings. This action is accomplished through the vacuum contact head  655 .  
         [0074]    The operation control commands from the control box  620  to the device  685  is through an electronic cable  675 .  
         [0075]    [0075]FIG. 7 is a schematic illustration in cross-section of human skin and illustrates the temperature changes at different parts of the skin, the temperature and heat regimen of the present invention to treat acne.  
         [0076]    When the heat is applied to the surface of the skin  710 , a tightly focused beam, operating for example at 2 W power and a spot size of 200 micrometers for a dwell time of about 0.1 ms can generate peak temperatures of up to a few hundred degrees centigrade in a shallow layer of the epidermis ranging down to about 30 micrometers into the skin. This is layer  770  in FIG. 6.  
         [0077]    If sufficient energy is provided, for example about 5 to 10 Joules/cm 2 , then the temperature of deeper layers of the skin, for example, the dermis  780  around and below the papillary dermis  720  as well as sebaceous glands  730  situated below the epidermis, can also be raised to above about 65° C., thus causing modification of the sebaceous gland, reducing sebaceous gland ability to generate sebum which drains into the hair follicles  770 . Overproduction of sebum and its accumulation in the hair follicle ducts is the cause of the acne symptoms and its reduction is another advantage of the present invention.  
         [0078]    It will be understood by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and sub-combinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art which would occur to persons skilled in the art upon reading the foregoing description.