METHOD AND DEVICE FOR SKIN TREATMENT USING OPTICAL

ENERGY AND RF

FIELD OF THE INVENTION The present invention relates to methods and systems for treating skin.

BACKGROUND OF THE INVENTION

Optical energy, particularly laser energy, is commonly used as a versatile tool in medicine and aesthetics to achieve desired effects in tissue treatment. For example, lasers have been used to treat common dermatological problems such as vascular lesions, pigmented lesions, acne scars, rosacea, hair removal, etc. Additionally, lasers have also been used for resurfacing the skin and remodeling the different skin layers to improve the appearance of textural or pigmented aged skin. Generally, skin resurfacing is understood to be the process by which the top layers of the skin are completely removed by chemicals, mechanical abrasion or lasers, to promote the development of new, more youthful looking skin and to stimulate the generation and growth of new skin. The most known method for skin resurfacing is ablation of the epidermis and the outer layers of the dermis of aged skin, using laser emission of wavelengths having strong absorption in water. Typical lasers used for skin ablation are continuous or pulsed CO ₂ and Er: YAG lasers, which are also known as "skin resurfacing" lasers. Using these devices, the upper layers of skin are completely ablated and removed to expose a layer deeper to the papillary dermis. Additionally, there may be heat-diffusion- induced coagulation to a depth of several tens or hundred micrometers below the original skin surface. Another method for such skin ablation involves the use of RF current, which is described in US Patent No. 6,309,387. This ablation treatment is used to reduce wrinkles and improve skin appearance. The main disadvantages of these treatments are the requirement for a long healing period, which can last more than a month, and a high risk of dischromia. These disadvantages of prolonged healing and dischromia risk characteristic of both laser-based and RF-based resurfacing have reduced the popularity of ablative resurfacing.

US Patent No. 6,702,808 discloses a method and apparatus for dermatological treatment in which RF and optical energy are applied, essentially simultaneously, to

heat a pigmented skin target in a cosmetic treatment such as hair removal, skin rejuvenation and vascular or pigmented lesions. The simultaneous application of both forms of energy to the skin heats the target without significantly raising the surrounding skin temperature. In laser skin remodeling, laser energy penetrates into the deeper layers of the skin and is aimed at stimulating the generation of and/or altering the structure of, extracellular matrix materials, such as collagen. The latter forms the bulk of the dermis material and contributes to the youthful appearance to skin.

Generally, the desired effects on the skin are accomplished by heating of the tissue. The induced heat results in thermal coagulation, cell necrosis, hemostasis, and/or gross alteration of the extra-cellular matrix depending on the particular combination of temperature and heating time used. When using lasers for either skin resurfacing or remodeling, one of the important objectives is to accomplish uniform treatment over the treated skin site by exposing the entire treatment area to the laser energy in such a way so as to uniformly heat the entire volume of tissue in the treatment area. As noted above in reference to US Patent No. 6,309,387, extensive, harsh treatment of wide areas of skin in addition to the prolonged healing time may also result in undesirable side effects such as intolerable pain, prolonged erythema, swelling, occasional scarring, and infection. Thus, a balance is required between excessive treatment of the skin and an effective administration of energy to the skin for remodeling and regenerative effects.

Specific, focused damage of the skin at a sufficient but not excessive level stimulates the synthesis, secretion and accumulation of collagen and improves the skin appearance. Another treatment method that has been developed in recent years, which attempts to generate a desired level of damage without incurring excessive damage is called "non-ablative skin resurfacing" and is based on heating the dermis to a sub- ablative temperature, with simultaneous preservative cooling of the epidermis. US Patent No. 5,810,801 describes use of infrared laser radiation penetrating into the skin dermis with dynamic cooling of the skin surface using a cryogen spray. US Patent No. 5,755,753 describes a method of skin tightening using an RF electrode creating non- ablative skin heating in combination with cooling. Non-ablative treatment is safer and reduces the required recovery time for the patient but the results of the treatment are more superficial.

US Published Patent Application No. 20030216719 attempts to maintain the efficiency of ablative treatment but with a shorter healing time and with a lower risk of adverse effects. The disclosed device coagulates portions of the skin in a fragmentary manner, by targeting multiple areas of very small size (approximately tens of microns) while maintaining a distance between these targeted areas which is larger than the targeted areas. This treatment provides healing of affected areas within a few days but the results are very superficial and less spectacular than with CO ₂ laser even after multiple sessions.

US Patent Published Application No. 20050049582 discloses a device and method for exposing a plurality of small areas of tissue to laser treatment. Each such area receives an amount of laser energy sufficient to cause tissue necrosis while overall skin damage is limited due to the small size of the treated area. Tissue cell activity and regeneration is stated to be stimulated in the areas of undamaged skin as well as which assists in healing of the areas of damaged skin. However, such a device and method suffer from similar drawbacks as for the above disclosures; application of a sufficiently strong amount of energy to cause a visually significant effect will also result in significant damage to the skin, while failure to apply a sufficiently intense energy will result in a less satisfactory result. ^f

More generally, all of the above devices and methods attempt to stimulate the tissue by causing some type of wound. For acute wounds, the skin heals by three distinct "response to injury" phases. The initial inflammatory phase has a duration lasting minutes to days, after which a cell proliferative phase begins, which lasts 1 to 14 days. This cell proliferative phase is slowly replaced by the dermal maturation phase that lasts from weeks to months (see, e.g., Clark, R. Mechanisms of cutaneous wound repair. In: Fitzpatrick T B, ed. Dermatology in General Medicine, 5.sup.th Ed., New York, N. Y. McGraw-Hill. 1999. pp. 327-41, which is incorporated herein by reference as if fully set forth herein).

In general, a direct correlation exists between the size of the wound and the time required for complete repair. However, the length and severity of the inflammatory phase is a function of cellular necrosis, particularly epidermal (i.e., keratinocyte) necrosis. Increased cellular necrosis prolongs and exacerbates the inflammatory phase. Prolonging and/or exacerbating the inflammatory phase may be undesirable from a clinical perspective due to increased pain and extended wound repair, as well as

cosmetically undesirable effects on the skin, and may retard subsequent phases of wound repair. Furthermore, such a prolonged and/or exacerbated inflammatory phase may also inhibit the patient from resuming normal daily activities.

The causes of this prolonged inflammatory phase are not well understood. However, laser injuries are associated with early and high levels of dermal wound repair activities (e.g., angiogenesis, fibroblast proliferation and matrix metalloproteinase (MMP) expression) but delayed epidermal resurfacing (See, e.g., Schaffer et al., Comparisons of Wound Healing Among Excisional, Laser Created and Standard Thermal Burn in Porcine Wounds of Equal Depth, Wound Rep. Reg. v5 (1) pp. 51-61 1997, incorporated herein by reference). Unfortunately, most of the skin resurfacing efforts that affect large contiguous areas result in a prolonged, inflammatory phase leading to undesirable consequences such as delayed epidermal wound repair. The prolonged inflammatory phase also leads to the pain experienced by most patients undergoing skin resurfacing procedures. Furthermore, the delayed epidermal resurfacing process may also lead to infections or to visually undesirable effects on the appearance of the skin.

An extended inflammatory response phase can be attributed to bulk damage of the skin with little or no healthy tissue, particularly keratinocytes, left behind for the healing process to occur efficiently. An extended inflammatory phase is often found when uniform treatment is desired and the entire target tissue volume is exposed to laser energy without sparing any tissue within the target volume. Thus, pain, swelling, fluid loss, prolonged re-epitheliazation, undesirable effects on the appearance of the skin, and other side effects, are commonly experienced by the patient.

When lasers act on the skin to cut, vaporize (ablate) or coagulate tissue, there are several "zones' of tissue damage that surround the spot where the impact of the laser energy is the highest, i.e., the treatment zone where the tissue volume is necrosed either completely or to a level above a threshold, such as a level where about 90% or more of the cells are necrosed. Usually, the temperature in the necrotic zone reaches a value over 7O ⁰ C, for a certain time period, and the tissue, whether it is made up primarily of cells, e.g., keratinocytes of the epidermis, or extra cellular matrix including collagen, e.g., the dermis, is necrosed or denatured, respectively.

The center of the necrotic zone is typically close to the center of the treatment beam. For heating times on the order of about 1-10 milliseconds, cell necrosis,

coagulation and protein denaturing will occur in a range of about 65-75 ⁰ C. Surrounding this zone is a larger zone of thermally altered but viable tissue known as the Heat-Shock Zone (HSZ) in which proteins and cells have been heated to supra-physiologic temperatures over a short time, but a significant percentage still remain viable. In portions of the HSZ, the volume of the tissue is exposed to temperatures typically in the range of 37° C to 45° C where nearly all cells survive the treatment. The dimensions of these zones depend on various laser parameters (such as the wavelength, pulse duration, energy density, etc.), thermal and optical properties of the tissue components, and ambient temperature. Recent data indicate that the HSZ has special significance for subsequent biological effects (see, e.g., Capon A. and Mordon S. Can thermal lasers promote wound healing? Am. J. Clin. Dermatol. 4(1): 1-12, 2003, which is incorporated herein by reference).

The change from one zone to another is not abrupt, but gradual. The necrotic zone and surrounding HSZ together form a volume of thermally-altered tissue. Outside that volume, essentially unaltered healthy tissue exists.

Heat shock in the thermally-altered zone triggers multiple signaling pathways that induce both cell survival and programmed cell death. The final outcome as to whether a cell lives or dies is believed to depend on the "acquired stress tolerance " of the surrounding tissue. Mild heat shock followed by a period of recovery makes the bulk of the surviving cells more active and more resistant to subsequent severe heat shock and several other forms of stress.

In conventional skin resurfacing and selective photothermolysis of contiguous chromophore regions, the laser exposed tissue can be dominated by the necrotic treatment zone instead of the viable, heat shock zone, depending upon the intensity of the laser energy and the pulse duration. In fact, such conventional treatments are designed to cover the target tissue in the plane of the skin completely with overlapping necrotic zones so that no target tissue is left unexposed to laser energy.

The prior art devices and methods suffer from a number of drawbacks. If a sufficient effect is achieved, it is frequently accompanied by significant damage to the skin and a prolonged healing period. Devices which do not cause such damage often do not provide satisfactory results.

SUMMARY OF THE INVENTION

The present provides a device and method for treating skin with a combination of RF (radiofrequency) energy and optical energy. In accordance with the invention, RF energy is applied to a skin region and laser energy is applied to a plurality of spots in the region. The optical energy by any source of optical energy, such as one or more lasers, light emitting diodes (LED), or intense pulsed light (IPL) sources. In a presently preferred embodiment, the optical source comprises one or more lasers.

The system of the invention comprises an applicator that is applied to the skin surface of an individual. The applicator includes one or more RF electrodes configured to generate an RF current in a region of skin referred to herein as "the RF region". The applicator also includes one or more sources of optical energy configured to illuminate a plurality of discrete spots on the skin surface over the RF region. The parameters of the RF energy and the optical illumination are selected to heat the skin volumes in the RF region to a desired temperature, as required in any application. The desired temperature may be, for example, a necrotic temperature, an ablative temperature, a sub necrotic temperature, or a combination of a necrotic temperature and an ablative temperature.

In one embodiment, the system of the invention is configured to first activate the optical system to irradiate the plurality of spots on the skin surface of the RF region. After formation of heated volumes in the RF region, the RF system is activated to generate an RF current in the RF region. In the case that the skin volumes have been heated to an ablative temperature, the volumes form blind holes filled with air (with possibly some cellular debris),, that may extend through epidermis and into dermis. In this case, the lower conductivity of the air in the interior of the holes causes the RF current density to be maximal close to the rim of the holes. The high density of the RF current around the holes heats the tissue surrounding each hole that is thus stimulated to begin a wound healing process and tissue regeneration.

In another mode of operation, the RF energy is applied first, to first heat the RF region, followed by application of the laser energy. In another embodiment, The RF and laser energies are applied simultaneous or substantially simultaneously to independently initiate and/or promote wound healing together with collagen stimulation by heating. Regardless of the order of application, heating of the RF region by the RF energy, combined with localized damage at discrete locations (and hence stimulation of

wound healing and direct stimulation of fibroblasts) by the laser irradiation or by the laser/RF combination can be used to provide a beneficial therapeutic effect.

The energy levels and area of application of the laser energy and of the RF energy are preferably selected so as to avoid or reduce excessive pain or inflammation, while still providing a maximal stimulatory effect on the skin. Since the skin damage is restricted to the small discrete spots in the RF region, discomfort to the patient and undesirable effects may be reduced in comparison to prior art methods. This would allow the subject to resume daily activities more quickly.

Thus, in one of its aspects, the invention provides a system for treatment of skin tissue, comprising:

(a) an RF system configured to generate an RF current in an RF region of the skin; and

(b) an optical system configured to illuminate a plurality of spots in the RF region and heat a plurality of skin volumes to a desired temperature.

In another of its aspects, the invention provides a method for treatment of skin tissue, comprising:

(a) generating an RF current in an RF region of the skin; and

(b) illuminating a plurality of spots in the RF region and heating a plurality of skin volumes to a desired temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in order to provide what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice, hi the drawings:

Fig. 1 shows a system for treating skin in accordance with one embodiment of the invention;

Fig.2 shows a block diagram of the processor of the embodiment of Fig. 1;

Fig.3A shows an applicator for use in the system of Fig. 1; Fig. 3B shows a second applicator for use in the system of Fig. 1 having a single

(monopolar) electrode;

Fig. 4A shows a third applicator for use in the system of Fig. 1 having a laser scanner;

Fig. 4B shows a third applicator for use in the system of Fig. 1 having a plurality of electrodes;

Fig. 5A shows illuminating a plurality of spots of a skin surface with laser radiation to heat a plurality of skin volumes to an ablative temperature;

Fig. 5B shows an RF current in an RF region following heating of a plurality of skin volumes to an ablative temperature; Fig. 5C shows the skin volumes after heating to an ablative temperature;

Fig. 6A shows RF current flow in an RF region having a skin volume previously heated to an ablative temperature;

Fig. 6B shows a temperature graph, with horizontal distance on the horizontal axis and temperature in °C on the vertical axis; and Fig. 7 shows a control unit for use in the system of Fig. 1

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 shows a system 100 treating skin in accordance with one embodiment of the invention. An applicator 703, to be described in detail below, contains one or more RF electrodes and one or more sources of electromagnetic radiation. The applicator 703 is adapted to be applied to the skin surface 118 of an individual 705. The applicator 703 is connected to a control unit 200 via a harness 311. As shown schematically in Fig. 7, the control unit 200 contains a processor 102 for monitoring and controlling an RF system 106 for generating an RF current in a region of skin referred to herein as "the RF region" skin, and an optical radiation system 104 for irradiating one or more spots in the RF region of the skin with electromagnetic radiation. The optical radiation system 104 includes a power source 111. The power source 111 provides power to one or more laser sources 110. The RF system includes a power source 115 that energizes an

electrode assembluyll2 that comprises one or more electrodes 114. The control unit 200 has user interface 212, such as a keypad shown in Fig. I ₅ , or a touch screen, and the like, that allows an operator to input selected values of parameters of the treatment, such as the frequency, pulse duration and intensity of the RF current or the wavelength and intensity of the optical energy.

Fig. 2 shows a block diagram of an exemplary embodiment of the processor 102. The processor 102 comprises the interface 212, and a sensing element 202. Sensing element 202 may include an optical, mechanical or electrical sensor or detector, such as, for example, an optical mouse, a mechanical mouse, capacitance sensor array or profilometer, but preferably comprises one or more thermal sensors 204 for sensing the temperature of skin and/or of one or more RF electrodes and one or more force sensors 206 for sensing force being applied to the skin.

The processor 102 may also control fluid pressure gauges, switches, buttons and the like. The processor 102 also contains a microprocessor 208 configured to determine a pattern of pulses of RF and/or laser energy to be used in a particular treatment. Microprocessor 208 can also control and/or acquire and analyze data from the sensors 206 and the user input 212. Microprocessor 208 can also control other components of apparatus 100 such as lights, LEDs, valves, pumps or other electronic components (not shown). The processor 102 can also contain a non-volatile memory 210, which can optionally be an EPROM or flash memory and the like. Non-volatile memory 210 can store a variety of data that can facilitate control and operation of system 100 and its associated system including but not limited to, (i) controlling the amount of current delivered by RF system 106, (ii) controlling the amount of energy delivered by optical radiation system 104, (iii) controlling the energy delivery duration time of the RF system 106 , and/or optical radiation system 104, (iv) controlling the temperature of the RF system 106 relative to a predetermined temperature, (v) providing a maximum number of activations of the RF system 106 and/or the optical radiation system 104, (vi) providing a maximum allowed voltage that is deliverable by the RF system 106, (vii) providing a maximum allowed amount of energy that is deliverable by the optical radiation system 104, (viii) providing a history of the RF system 106 and/or optical radiation system 104 usage, (ix) determining the sequence or order of application of current from the RF system 106 and the optical radiation system 104.

Fig. 3A shows an exemplary embodiment of an applicator 300a that may be used for the applicator 703. The applicator 300a has an upper housing 312 for housing various electrical components and tubes of the applicator 300a and also a spacer 305 for maintaining a fixed height of the housing 312 above the skin surface 118. The applicator 300a includes two RF electrodes 114a and 114b. Although two electrodes 114a and 114b are shown, the applicator 300a may contain any number of electrodes. Power to electrodes 114 is provided through wires 330a and 330b extending in the harness 311 from the power source 115 in the control unit 200 to the electrodes 1114a and b. When an RF voltage is applied across the electrodes 114a and 114b, an RF current 324 is generated in an RF region 328 of the skin. The RF electrodes 114a and b may have, for example, a diameter in the range of from about 0.010 to about 1.0 mm.

The upper housing 312 is above a lower housing 315, which contains the one or more laser sources 110. Power to a laser source 110 is provided through wires 331a and 331b extending in the harness 311 from the power source 111 in the control unit 200 to the laser source 110. Activation of the one or more laser sources 110 generates one or more laser beams 318 directed towards the skin surface that illuminate a plurality of spots 317

The laser source 110 may be a plasma source, preferably a plasma array. Use of a plasma array may provide beneficial treatment through a combination of ionizing energy and excitation energy, causing demarcated ablation at the skin surface. Depending upon the construction of the plasma array, a plurality of very small tissue areas may be irradiated, with a very small size of the plasma energy beam.

The system 100 is also provided with a cooling system 720 having a power source 715 and a cooling source 307 (Fig. 7). The cooling system 720 includes a delivery tube 307a that conducts a precooled fluid from a refrigeration unit 708 in the control unit 200 (See Fig. 1) through he harness 311 to the applicator 300. The delivery tube 307a is connected to a base 343 through with the precooled fluid flows before returning to the refrigeration unit 708 via a return tube 307b. The base plate 343 is in contact with the skin surface 118 and is made from a thermally conductive material such that as the cooling fluid flows in the base plate 343, heat is transferred from the skin surface 118 to the cooling fluid. The cooling fluid may be a water based substance, Freon or the like, or a combination thereof. The base plate 343 is configured not to

obstruct the laser beams 318. Alternatively, the cooling system may comprise a TEC (Thermo-electric-chiller), cooling gas, or any such system that is known in the art.

The system 100 may be provided with a vacuum system 740 (Fig. 7) a vacuum source 750 (Figs. 1 and 7) having a power source 745 located in the control unit 200 that removes debris created during operation of the system via a vacuum hose 716 extending in the harness 311 from the vacuum source 750 to the applicator 300a (not shown in Fig. 3a).

Fig. 3B shows an applicator 300b that may be used for the applicator 703, in accordance with another embodiment. The applicator 300b has several components in common with the applicator 300a, and similar components are indicated with the same reference numeral without further comment. The applicator 300b has a single (monopolar) electrode 420, which does not contact the skin surface 118. Electrical current is conducted between the electrode 420 and the skin surface 118 via air 406.

Fig. 4A shows an applicator 400a that may be used for the applicator 703, in accordance with yet another embodiment. The applicator 300c has several components in common with the applicator 300a, and similar components are indicated with the same reference numeral without further comment. The applicator 300c has a single laser source and a laser scanner 411. The laser scanner 411 comprises one or more mirrors 407a and 407b. Light energy is transmitted from laser source 110 to mirror 407b and is then reflected to mirror 407a, from which it is reflected on a path 410 to skin 118. The scanner 114 is operated so as to illuminate a plurality of discrete spots on the skin surface 118. Further details of the scanner may be found, for example, in US Patent No. 5,618,285, hereby incorporated by reference as if fully set forth herein. Such a laser scanner may be purchased from Sharplan Lasers (United Kingdom). The applicator 400a may include any of the components described above in reference to the applicators 300a or 300b, which are not shown in Fig. 4a, for the sake of clarity. In another embodiment (not shown), a single laser source is used with beam splitter is used for illuminating a plurality of spots 317 in the RF region.

Fig. 4B shows an applicator 400b that may be used for the applicator 703 in accordance with still another embodiment of the invention. The applicator 400 has two or more RF electrodes 114, a single laser source and a laser scanner 411, as described above. Each electrode 114 is held by a holder 418. The applicator 400b may include any

of the components described above in reference to the applicators 300a, 300b or 400a, which are not shown in Fig. 4b, for the sake of clarity.

In one embodiment, the system 100 is configured to perform as follows. The applicator 703 of the system 100 is applied to a skin region to be treated. The optical radiation system 104 is first activated to generate one or more light beams directed towards the skin surface so as to irradiate a plurality of discrete and separate spots on the skin surface the RF region of skin. Fig. 5 shows the applicator 300a while the system 100 is used in this way. In Fig. 5a, the laser source 110 has been activated to generate a plurality of laser beams 318 that are directed towards the skin surface 118 to irradiate a plurality of spots 317 on the skin surface in the RF region The optical energy penetrates into epidermis 301 and possible also into the dermis 302 and subcutaneous tissue 303. In one embodiment, the parameters of the laser energy are selected to ablate skin tissue in volumes 403 of the RF region that are filled with air. In another embodiment, the parameters of the laser energy are selected to heat the skin volumes 403 to a necrotic or sub necrotic temperature.

Next, as shown in Fig. 5b, after formation of the volumes 403 that may be blind holes or regions of necrosis in the RF region, an RF voltage is applied across the RF electrodes 114a and 114b to generate an RF current 324 in the RF region 328.

Fig. 5c. shows a sectional view of a portion of the RF region328 perpendicular to the skin surface, and Fig. 6a shows a sectional view of a portion of the RF region parallel to the skin surface, after the formation of the blind holes in the volumes 403 in the RF region. The volumes 403 extend through epidermis 301 and into dermis 302.

When the volumes 403 are blind holes filled with air, the lower conductivity of the air in the interior of the volumes 403 causes the current density to be maximal around the circumference of the volumes 403, as indicated in Fig. 6a. The high density of RF current around the volume 403 heats the tissue in a heated zone 512 around each hole 403 that is stimulated to begin a wound healing process and tissue regeneration.

Figure 6B shows the temperature dependence ( ⁰ C) in the vicinity of a volume 403. At the outer boundary 510 of the heated zone, the temperature begins to rise from 52°C to 60°C at the highest level at depression boundary 401. The temperature decreases within the volumes 403 to about 40 ⁰ C.

Applying the RF energy after formation of blind holes in the volumes 403 allows the RF energy to reach the deeper, collagen-rich, tissues. RF treatment of

collagen is known to be beneficial for restoring a more youthful appearance to the skin. The surrounding (non-ablated) tissue will be heated, increasing its electrical conductivity and enhancing the concentration of RF flow in these areas. In areas of the RF region where the skin is heated by the laser treatment heats to a non-ablative temperature, the RF current will flow more easily because an increase in tissue temperature reduces resistance and hence increases conductivity. hi another mode of operation, the RF energy is applied first, to first heat the RF region, followed by application of the laser energy. Regardless of the order of application, heating of the RF region by the RF energy, combined with localized damage at discrete locations (and hence stimulation of wound healing and direct stimulation of fibroblasts) by the laser irradiation can be used to provide a beneficial therapeutic effect. hi one presently preferred embodiment, one or both of the laser energy and the RF energy and/or RF energy is delivered as a train of pulses. The pulse duration of the RF energy should be short enough to prevent significant heat transfer out of the FR zone, and typically should not exceed 200ms. The RF energy should be adjusted to create selective damage around or between the RF electrodes 114. Selectivity of the treatment can be improved by electrode cooling, as is known in the art. Cooling also favors a more uniform heat distribution near the RF electrodes 114 and a more uniform heat distribution of the laser energy at the spots 317.

The energy levels and area of application of the laser energy and of the RF energy are preferably selected so as to avoid excessive inflammation and pain, while still providing a maximal stimulatory effect on the skin.

The optical energy may be applied in a sequence of both ablative and non- ablative pulses. Such a sequence may result in ablative depressions surrounded by areas of further heated tissue having increased electrical conductivity, which as noted above would result in increased RF current density around the holes and within the heated areas.

In another embodiment, The RF and laser energies are applied simultaneous or substantially simultaneously to independently initiate and/or promote wound healing together with collagen stimulation by heating.

RF energy and laser energy stimulate different processes on skin tissue and hence initiate different processes of rejuvenation in the skin - direct fibroblast

stimulation for collagen synthesis by the RF heating as well as wound healing related collagen synthesis, derived from the ablation, where the portions of the non ablated tissue serve as reservoir of cells for a rapid process. The heating may also cause apoptosis or collagen shrinkage. The amount of each type of energy that is applied may be sufficiently low so that little or no effect is seen from each type of energy separately, while a significant treatment effect is seen when both types of energy are applied to the same treated area.

The RF energy may optionally and preferably be applied at a sufficient intensity and/or duration to cause heating and/or denaturation and/or tissue shrinkage. The RF heating will also generally enhance fibroblast activity between the ablated areas.

The laser energy and/or RF energy may be sufficient to obtain collagen shrinkage as part of the treatment, thereby providing visible desirable treatment effects with little or no pain or other side effects.

Since the skin damage is restricted to the small discrete spots in the RF region, discomfort to the patient and undesirable effects may be reduced in comparison to prior art methods. This would allow the subject to resume daily activities more quickly.

The volumes 403 may be in the epidermal or dermal regions or extend from the epidermal region and continue into the dermal region of the skin. Preferably, the volumes 403 extend into dermal regions so that collagen in the dermis is targeted for treatment. The volumes 403 could have the shape of a cylinder, sphere, or any other shape that could be generated by an appropriate combination of wavelength, pulse duration, pulse width, beam profile, pulse intensity, contact tip temperature, contact tip thermal conductivity, contact lotion, numerical aperture of the focusing elements, optical source brightness, power, and so forth. Examples of lasers which may be used with embodiments of the present invention include, but are not limited to, solid state lasers, gas lasers, diode lasers. Non- limiting examples of such lasers include Er: YAG lasers, Nd: YAG lasers, Er:glass lasers, argon-ion lasers, He-Ne lasers, carbon dioxide lasers, fiber lasers, such as erbium fiber lasers, ruby lasers, frequency multiplied lasers, Raman-shifted lasers, optically-pumped semiconductor lasers (OPSL), and so forth. The laser source may be continuous wave (CW) or pulsed. However, it should be recognized that the selection of a particular type of laser light source in the optical system is dependent on the types of

dermatological conditions to be treated, on the desired effect to be achieved, and also optionally and preferably on the characteristics of the accompanying RF energy.

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 dermatological effect in the target tissue. The wavelength is typically chosen largely based on the target chromophore absorption spectrum whether the chromophore is naturally found in the skin, such as, for example, water, hemoglobin or melanin, or is added to the skin via topical or injection, such as, for example, drugs incorporating or attached to a chromophore. As an example, a laser light source can provide an optical beam having a wavelength or range of wavelengths between approximately 400 nm and 12,000 nm, and preferably from about approximately 500 nm to about 11,000 nm. The volumes 403 may have a cylindrical shape, and is from about 50 to about 500 microns in diameter, more preferably around 200 microns. For example, a laser light source can provide an optical beam having a wavelength of approximately 2,940 nm and an optical fluence incident on the exposed surface of the skin between approximately 0.001 Joules/cm ² and 100,000 Joules/cm ² , such as between approximately 1 Joules/cm ² and 1000 Joules/cm ² . The energy delivered would typically be less than about 100 mJ per spot 317, with a pulse duration from about 1 microsecond to 200 msec and more preferably less than about 100 msec. Optionally and preferably, the pulse duration of an optical beam can be approximately equal to or less than a thermal diffusion time constant, which is approximately proportional to the square of the diameter of a focal spot within the targeted portion, associated with the desired treatment zone, thereby preventing the spread of thermal energy. Alternatively if such a spread of energy is desired, the pulse duration may be greater than the thermal diffusion time constant. This might be needed to achieve a desired effect by itself, or in order to provide a synergistic effect with the applied RF energy by promoting conductance in the tissue as it is heated.

In one preferred embodiment, the spots 317 are preferably from about 50 to about 500 microns in diameter, with sufficient energy and/or for sufficient time to cause sufficiently deep tissue damage so that collagen tightening or shrinkage occurs, which would have immediate beneficial cosmetic effects. The volumes 403 may extend to a depth of between 10 and 4,000 microns into the skin. A shorter pulse with greater

energy is preferred to avoid a pulse duration longer than the thermal diffusion constant as described above, in order to cause deep damage, which may include collagen shrinkage, that is restricted to a defined portion of tissue. RF energy may also be applied simultaneously and/or within a short period of time following the laser energy, for example from 10 microseconds to 500 milliseconds after the termination of the laser illumination, in order to further tighten the collagen and cause additional damage, possibly to relatively deep layer(s) of the skin. However, longer or shorter pulses may also be applied. These combined effects may optionally and preferably be provided to induce sufficient damage for wound healing to occur, such that tissue regeneration occurs, preferably while minimizing undesirable cosmetic effects to the appearance of the skin.

The shape of the volumes 403 is determined by a combination of the wavelength of the light, the size and shape of the optical beam, the optical focusing, the topography of the skin surface and the laser pulse parameters (e.g., energy, duration, frequency). The wavelength of the light is selected for the optical absorption peaks of various components within the tissue and the scattering strength of the tissue. These optical transport parameters determine where the light energy travels in the tissue, and serve to partially determine the spatial temperature profile in the tissue. The size and shape of the optical beam and the focusing or numerical aperture of the laser determine the gross propagation properties of the beam inside the tissue. Size (e.g., diameter for a circular beam shape or cross-sectional width for a polygonal or irregularly shaped beam) and shape of the optical beam, particularly as the optical beam enters the tissue, typically affects the shape of the resulting necrotic zone. For example, a polygonal cross-section for the optical beam may produce a polygonal columnar necrotic zone, and a circular optical beam cross-section typically produces a circular or oval necrotic zone cross- section. Cross-sectional width for beam shape means the smallest distance across the cross-section in a line that includes the center of the cross-section. Cross-sectional width includes diameter, as diameter is simply a specific instance for a circular beam cross- section. Focusing, or numerical aperture (N.A.), is a significant factor for determining the ratio of the surface temperature of the tissue to the peak temperature reached in the most intensely affected zone. Embodiments of the present invention may include varying or alternating focal depths for one or more optical beams impacting a given treatment zone. For example, such embodiments may include multiple optical beams

focused to different depths, or the may include a single beam that is focused to varying depths within a treatment zone. The magnitude of the temperature profile is determined in part by the laser pulse energy.

The treatment zones may optionally be determined by adjusting one or more parameters such as the wavelength, external focus power (in diopters) or numerical aperture, external pressure on the skin, the presence or absence of a contact plate at the skin surface, the laser pulse energy and laser pulse duration, laser beam shape and size, and the repetition frequency of pulses. In addition or alternatively, the size and/or depth of the treatment zones could optionally be adjusted according to the placement and number of the RF electrodes, the length of time each RF pulse is applied and the amount of power applied through the RF electrodes. Without wishing to be bound by a particular theory, it is believed that this guiding effect is based on the temperature dependence of RF conductivity on temperature. In the temperature range of 20-90 degrees C, and for RF frequencies between 100 kHz and 100 MHz, there is a positive slope of tissue electrical conductivity versus temperature (see for example, "Physical Properties of Tissue", by Francis A. Duck, Academic Press Ltd., 1990, p.200). This positive slope generates a positive feedback effect, in which the preheated volumes have higher RF conductivity, therefore the RF current and energy deposition is higher in the preheated volumes which further raises the temperature of the focal volumes, which increases the conductivity even further. Some embodiments take advantage of the temperature-based shifts of the absorption features in skin to control precisely the shape and extent of the treatment zones.

According to an embodiment of the present invention, the skin may be deformed so that a portion protrudes from the surrounding skin. The protruding portion is preferably treated at the sides with RF energy (for example through the placement of an RF electrode at each side) and on the upper portion with laser energy. Optionally, a vacuum is used to induce a portion of the skin to protrude. US Patent No. 6,662,054 to Syneron, hereby incorporated by reference as if fully set forth herein, describes an apparatus and system for treating protruded skin with RF energy. According to another embodiment of the present invention, liquid or gel is applied to the skin surface in order to improve conductivity of the RF energy. The liquid or gel may be applied in a thin layer prior to treatment and/or during application of the RF energy. Alternatively or additionally, a spray and/or other form of liquid may

be applied between treatments with laser energy and treatment with RF energy, such that it is applied before treatment with RJF energy but does not substantially interfere with treatment with laser energy.

Preferred embodiments of the present invention may be suitable to treat a variety of dermatological conditions such as hypervascular lesions including port wine stains, capillary hemangiomas, cherry angiomas, venous lakes, poikiloderma of civate, angiokeratomas, spider angiomas, facial telangiectasias, telangiectatic leg veins; pigmented lesions including lentigines, ephelides, nevus of Ito, nevus of Ota, Hori's macules, keratoses pilaris; acne scars, epidermal nevus, Bowen's disease, actinic keratoses, actinic cheilitis, oral florid papillomatosis, seborrheic keratoses, syringomas, trichoepitheliomas, trichilemmomas, xanthelasma, apocrine hidrocystoma, verruca, adenoma sebacum, angiokeratomas, angiolymphoid hyperplasia, pearly penile papules, venous lakes, rosacea, wrinkles, etc. Embodiments of the present invention may be used to remodel tissue (for example, for collagen remodeling) and/or to resurface the tissue. While specific examples of dermatological conditions are mentioned above, it is contemplated that embodiments of the present invention can be used to treat virtually any type of dermatological condition. Additionally, embodiments of the present invention may be applied to other medical specialties besides dermatology. Other biological tissues may be treated with embodiments of the present invention, and in

/ particular tissues with structures similar to human skin may be treated. For example, tissues that have an epithelium and underlying structural tissues, such the soft palate, may be treated using embodiments of the present invention.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made.