Patent Description:
A conventional applicator or hand-piece for a tissue treatment system requires coolant flow to remove heat from the light source of the system and, in some cases, from the tissue being treated such as for pre-cooling prior to delivering the treatment pulse or for post cooling to remove added heat from the treatment pulse.

Separate coolant systems are used in conventional treatment systems requiring cooling for both the light source and the tissue. Thus, these systems typically include four coolant lines in a single umbilical cable that is connected between the applicator and a source of coolant. There are two delivery coolant lines and two return coolant lines. The first delivery coolant line delivers coolant from the coolant source to structure that engages and thus cools treated tissue. A first return coolant line returns the coolant from the structure back to the coolant source. A second delivery coolant line delivers coolant from the coolant source to be near the light source, such as a flashlamp, a flashlamp and laser rod, or a laser diode, to cool the light source and maintain the light source at a desired temperature. A second coolant return line returns the coolant that cools the light source back to the coolant source. This conventional coolant system with four coolant lines results in a bulky umbilical cable that is awkward for an operator to handle and such system increases material and assembly costs.

Thus, there is a need to provide cooling system for a tissue treatment system having only two coolant lines that can cool both the treated tissue and the light source.

<CIT> describes a known handpiece for treating biological tissue.

The invention and its most advantageous embodiments are defined in the appended claims.

An objective of the embodiment is to fulfill the need referred to above. In accordance with the principles of an embodiment, this objective is achieved by a tissue treatment system including a base unit having a power source and a reservoir for containing a cooling fluid. An applicator is connected with the base unit via a cable. The applicator includes a tissue cooling element constructed and arranged to engage biological tissue for treatment, the tissue cooling element including channel structure there-through; and a light source powered by the power source and constructed and arranged to generate light energy directed to the tissue cooling element and thus to the biological tissue. A first fluid passage is provided between the reservoir and the channel structure of the tissue cooling structure to deliver the cooling fluid through the tissue cooling structure. A second fluid passage is provided between the channel structure and the reservoir to return the cooling fluid to the reservoir. The second fluid passage is associated with the light source to direct cooling fluid to the light source prior to being returned to the reservoir. The first and second fluid passages define a single cooling fluid circulation loop to cool both the tissue cooling element and the light source. A portion of each of the first and second fluid passages is disposed in the cable.

In accordance with another aspect of an embodiment, a tissue treatment system includes a base unit having a power source and a reservoir for containing a cooling fluid. An applicator is connected with the base unit via a cable. The applicator includes a light source powered by the power source and constructed and arranged to generate light energy; a light guide disposed adjacent to the light source for directing the light energy to biological tissue; at least one thermoelectric cooler having a cold side and a hot side, the cold side being associated with the light guide; and at least one hot side plate mounted to the hot side of the thermoelectric cooler. A first fluid passage structure is provided between the reservoir and the hot side plate to deliver cooling fluid over the hot side plate to chill the cold side of the thermoelectric cooler and thus cool the light guide to cool the biological tissue. A second fluid passage structure is provided between the hot side plate and the reservoir to return the cooling fluid to the reservoir. The second fluid passage structure is associated with the light source to direct cooling fluid to the light source prior to being returned to the reservoir. The first and second fluid passage structures define a single cooling fluid circulation loop to cool both the light guide and the light source. A portion of each of the first and second fluid passage structure is disposed in the cable.

In accordance with yet another aspect of an embodiment, a method of cooling a tissue treatment system is provided. The system includes a base unit having a power source and a reservoir for containing a cooling fluid. An applicator is connected with the base unit via a cable with the applicator including a light source powered by the power source and constructed and arranged to generate light energy, and a tissue cooling element disposed adjacent to the light source for directing the light energy to biological tissue. A portion of the tissue cooling element is configured to contact the biological tissue. The method provides first fluid passage structure from the reservoir and extending to be associated with the tissue cooling element. The cooling fluid is delivered through the first passage structure to chill the tissue cooling element and thus cool the biological tissue. Second fluid passage structure is provided from the tissue cooling element to the reservoir to return the cooling fluid to the reservoir. The second fluid passage structure is associated with the light source. Prior to returning the cooling fluid to the reservoir, the cooling fluid is directed through the second passage structure to the light source to cool the light source. The first and second fluid passage structures define a single cooling fluid circulation loop to cool both the tissue cooling element and the light source. A portion of each of the first and second fluid passage structure is disposed in the cable.

Other objectives, features and characteristics of the present embodiment, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.

With reference to <FIG>, an embodiment of a tissue treatment system is shown, generally indicated at <NUM>, for treating biological tissue. The system <NUM> can be used to non-invasively deliver radiation to target biological tissue such as the skin or hair. The system <NUM> includes a base unit <NUM> and a delivery system, generally indicated at <NUM>. In the illustrated embodiment, the delivery system <NUM> includes an umbilical cable <NUM> and an applicator <NUM>. The applicator <NUM> can be a hand-held device, such as a handpiece, which can be held or manipulated by a user to irradiate the target tissue via a light source <NUM> provided in the applicator <NUM>. In one embodiment, light energy provided by the light source <NUM> is directed via the delivery system <NUM> to the target tissue.

The base unit <NUM> is coupled to the umbilical cable <NUM>, which is connected to a delivery module <NUM>. The base unit <NUM> includes a power source <NUM> that supplies power to various system components, including the light source <NUM>. The light source <NUM> can be a flashlamp used in intense pulsed light (IPL) systems, a flashlamp and laser rod used in solid state laser systems, or a diode laser used in diode laser systems for emitting light energy such as a light beam L (<FIG>) to the target tissue. A foot pedal (not shown) or finger switch on the applicator <NUM> can be employed to control the light source <NUM>. The base unit <NUM> also includes a controller <NUM> coupled with the light source <NUM> and which can be coupled to a user interface. The controller <NUM> includes a processor circuit <NUM>.

The base unit <NUM> includes a cooling system <NUM> that includes a reservoir <NUM> containing a coolant or cooling fluid <NUM> such as water or antifreeze. Antifreeze should be chosen to have minimal absorption to light energy or designed to work with fluid channels where light passes through sapphire only and not through antifreeze. With reference to <FIG>, the cooling system <NUM> includes a pump <NUM>, preferably in reservoir <NUM>, which pumps the cooling fluid <NUM> through a heat exchanger <NUM> which is delivered to the applicator <NUM> via a first fluid passage <NUM> and returned to the pump <NUM> via a second fluid passage <NUM>. Portions of fluid passages <NUM> and <NUM> are disposed in the umbilical cable <NUM>. The heat exchanger <NUM> is preferably a radiator combined with a fan to keep the cooling fluid <NUM> at a temperature close to or above ambient temperature. Instead of providing a heat exchanger <NUM>, a cooling module <NUM>' can be provided. The cooling module <NUM>' can be a thermoelectric cooling module or a compressor refrigerator system to maintain the cooling fluid <NUM> at a temperature below the ambient temperature.

With reference to <FIG>, tissue <NUM> located in a tissue treatment plane <NUM> is cooled by a portion of the applicator <NUM> being in contact with the tissue <NUM> located in the treatment plane <NUM>. Absence of effective cooling of the epidermis while heating the dermis and deeper skin layers during the course of light (laser) energy treatments can cause undesired pain to the treated subject and potentially undesired skin injury.

The applicator <NUM> provides contact cooling to the tissue by conduction of heat from the tissue <NUM> to a tissue cooling element or chilled tip <NUM> placed directly onto the tissue as will be explained below. As shown in <FIG>, the applicator <NUM> includes a housing <NUM> with a proximal end <NUM> and a distal end <NUM>. A support structure <NUM> is terminated by a frame <NUM> that extends from distal end <NUM>. Support structure <NUM> is angled to applicator <NUM> axis of symmetry A or off normal relative to axis of symmetry A of the applicator and improves line of sight to the skin treatment plane <NUM> or skin area <NUM> to be treated. The compliment of angle <NUM> at which support structure <NUM> is angled could be <NUM> to <NUM> degrees and usually the angle could be about <NUM> degrees.

The chilled tip <NUM> can be in the form of a window that is preferably made of transparent sapphire or quartz. The frame <NUM> of the support structure <NUM> includes a slot of rectangular or oval shape that receives the chilled tip <NUM>. For applications that combine RF energy with light energy to obtain a treatment effect, support structure <NUM> is made of metal or other material supporting good heat or cold conducting properties, and RF electrical conducting properties. The chilled tip <NUM> includes channel structure in the form of two cooling fluid channels <NUM> and <NUM> that communicate with each other. Typically, cooling fluid <NUM> is delivered through the first passage structure positioned on one side of the support structure <NUM>, and is passed through both channels <NUM> and <NUM>, then returned via the second passage structure positioned on the other side of support structure <NUM>. Alternatively, channel <NUM> can be considered an inlet channel and channel <NUM> can be considered an exit channel. Cooling fluid channels <NUM> and <NUM> provided through the chilled tip <NUM> are in fluid communication with fluid passages <NUM> and <NUM>. Thus, cooling fluid <NUM> from the reservoir <NUM> is pumped by the pump <NUM> through the fluid passage <NUM> to cooling fluid channel <NUM> of the chilled tip <NUM> to cool the chilled tip <NUM> and thus cool the tissue in contact therewith. Prior to entering the chilled tip <NUM>, the cooling fluid <NUM> is at a temperature of about <NUM> to <NUM>. The heat-absorbed cooling fluid <NUM> exits the chilled tip <NUM> via cooling fluid channel <NUM> at a temperature of about <NUM> to <NUM>, and is returned to the reservoir <NUM> via fluid passage <NUM>. Cooling fluid channels <NUM> and <NUM> can be considered to be part of the fluid passages <NUM> and <NUM>, respectively.

<FIG> show an example of the tissue cooling element or chilled tip <NUM> that includes communicating cooling fluid channels <NUM> and <NUM> having generally circular cross-section. Other shapes of the channels <NUM>, <NUM> can be employed such as disclosed in <CIT>. Chilled tip <NUM> with cooling fluid channels <NUM> and <NUM> delivers cooled or chilled cooling fluid <NUM> (e.g., preferably water, but can be antifreeze) directly to and through the chilled tip <NUM> that is in contact with skin (see <FIG>. ) The proximity of the cooled or chilled water with the skin surface reduces the thermal resistance of the chilled tip <NUM>. The thermal resistance just under <NUM>/W is easily obtained by optimization of the chilled tip design. (In comparison for the thermoelectric cooler (TEC) cooled chilled tip designs, thermal resistances are typically around <NUM>/W. ) In general, the cooling fluid channels <NUM>, <NUM> are positioned near to but outside of the transmitted optical path to avoid lensing affects at the interface due to unmatched refractive indices between the fluid and transparent window material.

The chilled tip <NUM> can be configured to include two plates, a sapphire plate for contacting the tissue <NUM> and a less thermally conductive glass plate with the cooling fluid <NUM> flowing in channel structure defined between the two plates. The glass plate minimizes condensation on top surface that faces the light source <NUM>.

With reference to <FIG>, a light guide <NUM> may be provided between the light source <NUM> and the chilled tip <NUM>. The light guide <NUM> can be in the form of a hollow cone with mirrored walls to reflect light from the light source <NUM> to the chilled tip <NUM> and thus to the tissue <NUM>. Alternatively, the light guide <NUM> can be an optical prism or waveguide. Thus, a beam L of optical energy from the light source <NUM> is directed through the light guide <NUM>, through the chilled tip <NUM> and to the tissue <NUM> to irradiate the skin or tissue at area <NUM> defined by the chilled tip <NUM> being in contact with the tissue <NUM> on the skin treatment plane <NUM>. The chilled tip <NUM> can be considered to be a portion of the light guide <NUM>.

A cable <NUM> extends from proximal end <NUM> of the applicator housing <NUM> and connects the applicator <NUM> to the power source <NUM> and controller <NUM>.

In use, applicator <NUM> is applied to the skin or tissue treatment plane <NUM> and the beam L of optical energy can be activated to apply treatment energy through the chilled tip <NUM> to the skin or tissue treatment plane <NUM>. The chilled tip <NUM> and thus the tissue <NUM> in contact therewith is cooled via the cooling fluid <NUM> circulating through the chilled tip <NUM> as explained above.

Advantageously, in accordance with the embodiment, the two fluid passages <NUM>, <NUM> can be employed to also cool the light source <NUM>. As shown in <FIG> and as best shown in <FIG>, the after the cooling fluid <NUM> passes through the chilled tip, fluid passage <NUM> is provided through or adjacent to at least a portion of the light source <NUM> to direct the cooling fluid <NUM> through or on the portion of the light source <NUM>. If the light source <NUM> includes a flashlamp and laser rod, the light source <NUM> can sit within a bath of the cooling fluid <NUM> created by fluid passage <NUM>. If the light source is a diode laser, the cooling fluid can be directed via passage <NUM> through small fluid channels <NUM> in the light source <NUM> to cool diode laser bars and stacks. As shown in <FIG>, the cooling fluid <NUM> enters the light source at a temperature of about <NUM> to <NUM>. Thus, the fluid passages <NUM> and <NUM> define a single cooling fluid circulation loop between the reservoir <NUM>, the chilled tip <NUM> and the light source <NUM>.

<FIG> shows another embodiment of the cooling system which is similar to the embodiment of <FIG>, but a heat source such as a heater or radiator <NUM> is provided in fluid passage <NUM>. Thus, in systems where a large temperature difference exists between tissue cooling and light source cooling, such as <NUM> for tissue cooling and <NUM> for light source cooling, the heater coil or radiator <NUM> can be provided to increase or control the temperature of the cooling fluid <NUM> before entering the light source <NUM>.

<FIG> is a side view of another embodiment of the cooling system having light source <NUM> and a tissue cooling element in the form of a light guide <NUM>', preferably a waveguide in the form of a prism. No transparent window is provided. <FIG> is a top or plan view of <FIG>. A thermoelectric cooler (TEC) <NUM> is provided generally adjacent to at least one side of the light source <NUM>. In the embodiment, a TEC <NUM> is provided generally adjacent to opposing sides of the light source. Hot side and cold side plates <NUM>, <NUM>' respectively, sandwich each TEC <NUM>, with the hot side plate <NUM> being in contact with each side of the light source <NUM>. Also, each hot side plate <NUM> is in contact with the hot side <NUM> of each thermoelectric cooler <NUM>. A first portion <NUM> of each cold side plate <NUM>' is mounted to the cold side <NUM> of the associated thermoelectric cooler <NUM> and a second portion <NUM> of each cold side plate <NUM>' is mounted directly to the light guide <NUM>' (<FIG>). With reference to <FIG>, cooling fluid <NUM> from the reservoir <NUM> is directed via a first fluid passage structure <NUM> over each hot side plate <NUM> to chill the cold side plates <NUM>'. The cold side plates <NUM>' cool the light guide <NUM>' to cool the tissue being treated. Upon leaving the hot side plates <NUM>, the cooling fluid is directed, via a second fluid passage structure <NUM>, into the light source <NUM> to cool the light source <NUM>. The now hotter cooling fluid <NUM> then exits the light source <NUM> and is directed back to the reservoir <NUM> via the second fluid passage structure <NUM>. Similar to the embodiment of <FIG>, a portion of each of the first and second passage structures <NUM> and <NUM> extends through the cable <NUM>.

<FIG> shows yet another embodiment for cooling the light source <NUM> and light guide <NUM>'. Again, the tissue cooling element or light guide <NUM>' is preferably a waveguide in the form of a prism. In this embodiment, no transparent window is provided and no cold side plates are provided. Instead, the cold side <NUM> of the TEC <NUM> is mounted directly onto the waveguide <NUM>'. This configuration is more efficient compared to the use of cold side plates since there is less thermal resistance. Cooling fluid <NUM> is delivered from the reservoir <NUM> via first passage structure <NUM> and passes through or flows over the hot side plates <NUM> to cool the cold side <NUM> of the TEC <NUM> and cool the waveguide <NUM>', and thus cool the tissue being treated. Thereafter, the cooling fluid <NUM> passes through the light source <NUM> to cool the light source. The cooling fluid <NUM> returns to the reservoir <NUM> via fluid passage structure <NUM>. Similar to the embodiment of <FIG>, a portion of each of the first and second passage structures <NUM> and <NUM> extends through the cable <NUM> (not shown in <FIG>).

The system <NUM> can be employed for multiple applications but is preferably used for hair removal. For use in hair removal, the light source <NUM> is preferably one of a <NUM> Alexandrite laser, a semiconductor diode laser operated around <NUM>, preferably at <NUM> or <NUM>, and a <NUM> Nd:YAG laser preferably employed to a depth of about <NUM>. Selection of the light source <NUM> depends on the desired type of treatment.

Thus, the tissue treatment system <NUM> having the cooling system of the embodiments provides an effective way to cool both the tissue <NUM> being treated and the light source <NUM> using a single delivery fluid passage <NUM> and a single return fluid passage <NUM> between the applicator <NUM> and cooling fluid reservoir <NUM>. Thus, the umbilical cable <NUM> is not bulky and less cooling pluming is required, reducing cost.

Claim 1:
A tissue treatment system (<NUM>) comprising:
a base unit (<NUM>) having a power source (<NUM>) and a reservoir (<NUM>) for containing a cooling fluid (<NUM>),
an applicator (<NUM>) connected with the base unit (<NUM>) via a cable (<NUM>), the applicator (<NUM>) comprising:
a tissue cooling element (<NUM>) constructed and arranged to engage biological tissue (<NUM>) for treatment, the tissue cooling element (<NUM>) including channel structure (<NUM>, <NUM>) there-through,
a light source (<NUM>) powered by the power source (<NUM>) and constructed and arranged to generate light energy directed to the tissue cooling element (<NUM>) and thus to the biological tissue (<NUM>),
a first fluid passage (<NUM>) disposed between the reservoir (<NUM>) and the channel structure (<NUM>, <NUM>) of the tissue cooling element (<NUM>) and configured to deliver cooling fluid (<NUM>) at a first temperature to the tissue cooling element (<NUM>) to cool the biological tissue (<NUM>), such that the cooling fluid (<NUM>) is heated to a second temperature upon heat exchange with the biological tissue (<NUM>), and
a second fluid passage (<NUM>) disposed between the channel structure (<NUM>, <NUM>) and the reservoir (<NUM>) and configured to return the cooling fluid (<NUM>) to the reservoir (<NUM>), the second fluid passage (<NUM>) being constructed and arranged to direct the cooling fluid (<NUM>), at the second temperature, to the light source (<NUM>) to cool the light source (<NUM>) prior to being returned to the reservoir (<NUM>),
wherein the first (<NUM>) and second (<NUM>) fluid passages define a single cooling fluid circulation loop to cool both the tissue cooling element (<NUM>) and the light source (<NUM>) in series, and wherein a portion of each of the first (<NUM>) and second (<NUM>) fluid passages is disposed in the cable (<NUM>).