Patent Publication Number: US-2021177515-A1

Title: Cooled Laser Fiber And Method For Improved Thermal Therapy

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/155,657 filed on May 16, 2016, which is a continuation of U.S. patent application Ser. No. 14/508,050 filed on Oct. 7, 2014, now U.S. Pat. No. 9,339,336 issued on May 17, 2016, which is a continuation of U.S. patent application Ser. No. 13/493,699 filed on Jun. 11, 2012, now U.S. Pat. No. 8,851,080 issued on Oct. 7, 2014, which is a continuation of U.S. patent application Ser. No. 11/749,854 filed on May 17, 2007, now U.S. Pat. No. 8,211,095 issued on Jul. 3, 2012, which is a continuation-in-part of U.S. patent application Ser. No. 10/703,304 filed on Nov. 7, 2003, now U.S. Pat. No. 7,270,656 issued on Sep. 18, 2007. The entire disclosures of each of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     This disclosure, in general, relates to energy delivery apparatuses, energy delivery systems, and methods for using same. 
     BACKGROUND 
     Laser interstitial thermal therapy (LITT) is a clinical tool for treating various malignant tumors in the liver, brain, ENT, or abdominal locations, as well as for treating benign alterations, such as prostate adenomas. Fiber optics that terminate in either bare fibers or diffusing applicators are punctured into the pathological volume to deliver the laser energy within the desired region of treatment. After positioning of the fibers, target tissues are irradiated causing volumetric heating that leads to thermal tissue necrosis. Tumor destruction with direct heating is therefore possible, while greatly limiting side effects or additional damage to surrounding structures. Furthermore, such thermal methods are associated with faster recovery than conventional surgical resection procedures. 
     Large applicators may cause trauma to healthy tissue when accessing the pathological volume. Applicators where light distribution results in high power density and heat generation, exceeding the thermal diffusion into the tissue can cause areas close to the applicator to char and potentially vaporize. Charring limits heat deposition within deeper tissue volumes due to increased absorption of light energy. As charred tissue continues to absorb incident light, its temperature continues to rise, leading to carbonization around the applicator. Further coagulation of deeper layers is dependent on heat conduction away from this carbonized volume. 
     While it is indeed possible to create large thermal lesions in this manner, the morphology of the resulting lesion is undesirable. Furthermore, high temperatures associated with the carbonized tissue often result in failure of the applicator tip and fiber optic with significant attendant risk for patients. As such, an applicator that limits charring and vaporization would be desirable. 
     Typical applicators are multi-component applicators. Procedures utilizing these applicators involve multiple insertion steps and time consuming actions taken by the medical professional performing the procedure. Such steps and actions prolong the surgical process and endanger the patient. In addition, multiple insertion steps potentially cause slippage of catheters and additional damage to surrounding tissue. As such, an improved applicator would be desirable. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     [INSERT SUMMARY DESCRIPTION] 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1A  is a block diagram and plan view of an exemplary energy delivery apparatus in accordance with an embodiment of the disclosures made herein. 
         FIG. 1B  is a partial fragmentary side view depicting an embodiment of a distal portion of the energy delivery apparatus depicted in  FIG. 1A . 
         FIG. 1C  is a partial fragmentary side view depicting an embodiment wherein the energy delivery component includes a diffusing tip element. 
         FIG. 1D  is a partial fragmentary side view depicting an embodiment wherein the energy delivery component has a bare tip optical waveguide. 
         FIG. 1E  is a partial fragmentary side view depicting an embodiment wherein the energy delivery component includes a diffusing tip element with reflective means for selective angular energy emission. 
         FIG. 1F  is a cross sectional view depicting an embodiment of a distal section of the energy delivery apparatus. 
         FIG. 1G  is a cross sectional view depicting an alternative embodiment of a distal section of the energy delivery apparatus with means for maintaining consistent lumen dimensions during use. 
         FIG. 1H  is a partial fragmentary side view depicting an embodiment of a proximal portion of the energy delivery apparatus depicted in  FIG. 1A . 
         FIG. 1I  is a schematic diagram illustrating an embodiment of an energy delivery apparatus. 
         FIG. 2A  is a diagrammatic view depicting an embodiment of a method of treatment with an energy delivery apparatus of a Cooled Laser Fiber (CLF) system. 
         FIG. 2B  is a diagrammatic view depicting an exemplary embodiment of a method of treatment with an energy delivery apparatus of a CLF system. 
         FIG. 3A  is a partial fragmentary side view depicting an embodiment of a distal portion of the energy delivery apparatus depicted in  FIG. 1A  having embedded scattering centers in the distal tip. 
         FIG. 3B  is a partial fragmentary side view depicting an embodiment of a distal portion of the energy delivery apparatus depicted in  FIG. 1A  having reflective means at the distal tip. 
         FIG. 3C  is a partial fragmentary side view depicting an embodiment of a distal portion of the energy delivery apparatus depicted in  FIG. 1A  with means for perfusing tissue adjacent to the energy delivery apparatus. 
         FIG. 3D  is a partial fragmentary side view depicting an embodiment of a distal portion of the energy delivery apparatus depicted in  FIG. 1A  that allows infusion of fluids through the distal tip by retraction of the diffusing tip optical waveguide 
         FIG. 3E  is a partial fragmentary side view depicting an embodiment of a distal portion of the energy delivery apparatus depicted in  FIG. 1A  having an optically transmissive coating that provides a non-stick surface. 
         FIG. 3F  is a partial fragmentary side view depicting an embodiment of a distal portion of the energy delivery apparatus depicted in  FIG. 1A  having a stepped down diameter at the distal end of the energy delivery apparatus. 
         FIGS. 3G-3J  are partial fragmentary isometric views depicting embodiments of outer housing and tubular structures of the energy delivery apparatus depicted in  FIG. 1A  with reflective materials used for selective angular energy emission. 
         FIG. 4A-4G  are cross sectional views depicting alternative embodiments of a distal section of the energy delivery apparatus. 
         FIGS. 5-7  are flow diagrams depicting exemplary methods for use of the apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Energy delivery systems, such as Cooled Laser Fiber (CLF) systems, may be used to treat tissue within a patient. For example, a CLF system may be used to treat diseased tissues such as malignant and benign tumors and adenomas. In one exemplary embodiment, an energy delivery apparatus is inserted into the tissue, laser energy is dispersed within the tissue, and as a result, thermal necrosis occurs. The CLF system may be utilized to facilitate thermal coagulation of tissue, and more particularly to treat solid cancerous tumors in soft tissue, such as human and animal tissue. 
       FIGS. 1A-1H  depict embodiments of an exemplary energy delivery apparatus of a Cooled Laser Fiber (CLF) system. As illustrated in  FIG. 1A , the CLF system includes an energy delivery apparatus  1 , an energy delivery component  2 , an energy source  4 , and a cooling media supply apparatus  6 . The proximal end of the energy delivery component  2 , is coupled to the output of the energy source  4 . The distal end  3  of the energy delivery component  2 , extends within the energy delivery apparatus  1 . The cooling medium supply apparatus  6  is connected to the inlet fluid port  8  of the energy delivery apparatus  1 . The outlet fluid port  10  is either connected back to the cooling medium supply apparatus  6  (recirculating system) or to a suitable waste collection area (non-recirculating system). 
     In the exemplary embodiment depicted, the energy delivery apparatus  1  includes a housing  12  attached to a coupling assembly  26 . A structure  16  separates the lumen of housing  12  into two channels. A first channel  20  is formed between the structure  16  and the housing  12  and a second channel  18  is formed between the energy delivery component  2  and the structure  16 . The channels  18  and  20  communicate near or proximate the distal end of the housing  12  to allow fluid to pass from one channel to the other. The channels  18  and  20  may be isolated proximate the coupling assembly to allow fluid to, for example, enter port  8 , flow through channel  18 , return through channel  20 , and exit via the outlet port  10 . However, in other embodiments, the fluid may flow in the opposite direction. In this manner, counter current cooling fluid flow cools the housing  12 , the structure  16 , the energy delivery component  2 , and the surrounding tissue. In the above exemplary embodiment, the structure  16  is depicted as tubular and the channels  18  and  20  are depicted as annuluses or concentric flow paths. However, various shaped structures  16  or shaped housings  12  may be used to form channels. As such, the tube-like structures,  12  and  16 , may have cross-sectional shapes such as stars, squares, triangles, ovals, circles, and other shapes. 
     In one exemplary embodiment, the energy delivery apparatus  1  and the energy delivery component  2  are integrated or assembled just prior to insertion into the tissue. In another exemplary embodiment, the energy delivery apparatus  1  and the energy delivery component  2  are integrated or assembled during manufacture prior to being delivered for use. 
     Referring to  FIGS. 1B through 1E , energy delivery apparatus  1  includes a flexible outer housing  12  having a tubular structure along its length and a penetrating tip  14  at its distal end. The outer housing  12  may, for example, be rigid enough to penetrate soft tissue without kinking, yet be flexible enough to follow curved or arcuate paths. The solid penetrating tip  14  may take the form of a cutting edge or a point, among others. The housing  12  contains an inner tubular structure  16  within its lumen that extends between a proximal end and a distal end of the outer housing  12 . The inner tubular structure  16  may be centered within the housing  12  to create fluid inlet lumen  18 , and fluid outlet lumen  20 . The inlet and outlet lumens ( 18  and  20 ) facilitate delivery and return of cooling media (e.g. water, saline, or carbon dioxide, among others) to and from the distal end of the energy delivery apparatus  1 . The fluid inlet lumen  18  facilitates housing of the energy delivery component  2 . Suitable materials for the flexible outer housing  12 , and inner tubular structure  16  include flexible radio-opaque and non radio-opaque medical grade plastic tubing, such as polycarbonate (Makrolon, Bayer Polymers), polyurethane, polyethylene, polypropylene, silicone, nylon, polyvinylchloride (PVC), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), acrylonitrile butadiene styrene (ABS), polyether sulphone (PES), polyetheretherketone (PEEK), fluorinated ethylene propylene (FEP), other biocompatible polymers, or any combination thereof. 
     In one particular embodiment, the inner diameter of the inner tubular structure  16  may range from 0.6 mm to 2.0 mm, such as between 0.9 mm and 1.1 mm. The outer diameter of the inner tubular structure  16  may range from 0.7 mm to 2.1 mm, such as between 1.0 mm to 1.2 mm. The inner diameter of the outer housing may range from 1.0 mm to 1.9 m, such as between 1.2 mm and 1.4 mm, and the outer diameter of the outer housing may range from 1.2 mm to 2.5 mm, such as between 1.3 mm and 1.6 mm or less than 1.5 mm. For example, in a preferred embodiment in which a 0.4 mm core diameter fiber optic is used as the energy delivery component, and which is further provided with a buffer jacket of 0.730 mm outer diameter (OD), the inner tubular structure  16  is preferably 1.09 mm ID and 1.17 mm OD, and the outer housing is preferably 1.37 mm ID and 1.57 mm OD. Prefabrication or integration permits smaller diameters, which cause less peripheral tissue damage and may be easier to guide through tissue. 
     The energy delivery component  2  disposed within the fluid inlet lumen includes one or more optical waveguides positioned to direct light through both the inner tubular structure  16  and outer housing  12 . In a particular embodiment, the energy delivery component  2  may be movable relative to the energy delivery apparatus  1 , for example, translating along the axis of the energy delivery apparatus  1 . Energy emitted from a diffusing tip of the energy delivery component  2  may pass through transparent housing  12  and structure  16 . More than one region of tissue located along the housing  12  may be treated by moving the energy delivery component  2 . 
     In at least one embodiment, the distal end  3  of the energy delivery component  2  preferably consists of an optical waveguide terminated with a diffusing tip element  9 , as illustrated in  FIG. 1C . The diffusing tip element  9  is designed to emit light  19  in a uniform cylindrical pattern around the center axis of the waveguide. In at least one embodiment, the waveguide is an optical fiber with core  5 , cladding 11, and protective jacket  7 . In an alternative embodiment illustrated in  FIG. 1D , energy delivery component  2  may consist of a bare tipped optical waveguide in which the distal end of the optical waveguide is polished flat resulting in a forward propagation of emitted energy  19 . In yet another alternative embodiment, energy delivery component  2  may consist of an optical waveguide terminated with a selective angular emitting element  15 , as illustrated in  FIG. 1E . The angular emitting element  15  may be constructed by placing a reflective material  17  over a section of a diffusing tip element  9  thereby preventing significant energy from passing through that section of the element. Suitable materials for the reflective material  17  include polished surfaces of gold, silver, aluminum, and other reflective materials. In one exemplary embodiment, the energy delivery component  2  may be rotated to direct photons  19  emitted from the angular emitting element  15 . 
     A cross section of a distal portion of an energy delivery apparatus  1  is illustrated in  FIG. 1F . In at least one embodiment, the fluid inlet lumen  18  is defined by the space between the energy delivery component  2  and the inner wall of the inner tubular structure  16 . The fluid outlet lumen  20  is defined by the space between the outer wall of the inner tubular structure  16  and the inner wall of the outer tubular housing  12 . In alternative embodiments, the cross-sectional shape of the energy delivery apparatus may take forms such as a circle, triangle, star-shape, and oval, among others. In further embodiments, the outer housing may be shaped to form separate channels. In another exemplary embodiment, the structure  16  may be corrugated to provide channels. The outer surface of housing  12  may be shaped to increase heat transfer surface area. 
     A cross section of an alternative embodiment of the energy delivery apparatus  1  is illustrated in  FIG. 1G . In one embodiment, energy delivery apparatus  1  may include one or more inner spacers  22  located between inner tubular structure  16  and energy delivery component  2  or may include one or more outer spacers  24  located between inner tubular structure  16  and outer tubular housing  12 . The inner spacers  22  may maintain a consistent distance between energy delivery component  2  and inner tubular structure  16  around the circumference of energy delivery component  2  such as to maintain consistent lumens or to limit movement of one lumen with respect to the other. Similarly, the purpose of outer spacers  24  is to maintain a consistent distance between inner tubular structure  16 , and outer tubular housing  12  around the circumference of inner tubular structure  16 . It should be noted that inner spacers  22  and outer spacers  24  may extend along the entire length of energy delivery apparatus  1  or alternatively may only be located along discrete sections where maintaining consistent profiles may be more important such as near the distal end  3  of energy delivery component  2 . In alternative embodiments, the structure  16  or the housing  12  may be shaped to form channels or provide structural integrity for maintaining open lumens. 
     Referring to  FIG. 1H , a coupling assembly  26  is attached at the proximal end  28  of the outer housing  12 . The coupling assembly  26  includes the inlet fluid port  8 , outlet fluid port  10  and an opening  30  for introducing an energy delivery component  2 . A suitable coupling assembly may be formed by mating two male-female taper luer tees, such as part #LT878-9, Value Plastics, Inc. A male Touhy Borst connector  32 , such as part #80344 Qosina, may be included to provide a leak-proof seal at the energy delivery component opening  30  and for securing the energy delivery component  2  to the coupling assembly  26 . The distal segment  34  of the coupling assembly is bonded to the outer housing  12  to create a fluid tight seal. A proximal section  36  of coupling assembly  26  contains a seal  38  between the inner tubular structure  16  and the proximal section  36  to prevent fluid communication between inlet fluid port  8  and outlet fluid port  10  within the coupling assembly  26 . Both distal and proximal seals and other bonds may be created using a suitable UV cure epoxy, such as Part #140-M, Dymax Corp. Alternative methods of bonding and sealing may be used including various cyanoacrylates, epoxies, silicones, heat bonds, press fits, and threaded assemblies, among other methods. It is contemplated that the opening  30  and one of inlet fluid port  8  or outlet fluid port  10  may be coincident. In an alternative embodiment,  FIG. 1I  portrays a schematic of an integrated energy delivery apparatus wherein fluid outlet port  10  and energy delivery component opening  30  mutually comprise one another. 
     Returning to  FIG. 1H , a heat transfer medium supply passage  40  extends between the inlet fluid port  8  and the fluid inlet lumen  18  for enabling flow of heat transfer medium from a heat transfer medium supply apparatus  6  through the coupling assembly  26  into the fluid inlet lumen  18 . A heat transfer medium return passage  42  extends between the fluid outlet port  10  and fluid outlet lumen  20  for enabling flow of heat transfer medium from the fluid outlet lumen  20  through the coupling assembly  26  and out of the energy delivery apparatus  1 . The heat transfer medium, for example, may be a cooled medium, a heated medium, or a medium having a temperature different than that of the tissue, such as a room-temperature medium. 
     An embodiment of a heat transfer medium supply apparatus may be a circulation type medium supply apparatus or a non-circulation type medium supply apparatus. In a circulation type medium supply apparatus, heat transfer medium is supplied from a reservoir to the energy delivery apparatus  1  and back to the reservoir. In a non-circulation type medium supply apparatus, heat transfer medium is supplied from a supply reservoir to the energy delivery apparatus  1  and then to a separate return reservoir. An example of a non-circulation type medium apparatus system includes a syringe pump, wherein a body of a syringe is a supply reservoir. Benefits of the use of a syringe pump include ease of metering the heat transfer medium and reduced potential for contamination of heat transfer medium being supplied to the circulation chamber. Suitable syringe pumps are commercially available from New Era Pump Systems Corporation and from Harvard Apparatus Corporation. 
       FIG. 2A  depicts an embodiment of a method for utilizing the energy delivery apparatus  1  depicted in  FIGS. 1A through 1E . The distal portion  44  of the energy delivery apparatus  1  is inserted into the tissue  46  of a patient and directly within the diseased tissue  48 . The distal portion  44  may be guided into the tissue  46  via a percutaneous approach under a known guidance approach such as fluoroscopic, MRI, ultrasound, CT, stereotaxis, among others. In one exemplary embodiment, the energy delivery apparatus is inserted through a guide hole or incision. In another exemplary embodiment, the energy delivery apparatus may be inserted directly into tissue without an introducer or catheter. Once at a location to be treated, such as within the diseased tissue  48 , energy is delivered into the diseased tissue  48  after passing from an energy source  4 , through the energy delivery apparatus  2 , through the medium within the fluid inlet lumen  18 , through the inner tubular structure  16 , through the medium within the fluid outlet lumen  20 , and through the outer housing  12 . In one embodiment, the energy source  4  is a laser operating at a wavelength between 350 nm and 2100 nm, such as at about 980 nm. 
     During delivery of energy, a cooling medium is introduced into the energy delivery apparatus  1  such that it flows through the fluid inlet lumen  18  around and in contact with the energy delivery component  2 . The cooling medium exits the fluid inlet lumen  18  at the distal end of the inner tubular structure  16  and enters the fluid outlet lumen  20  at the distal end of the outer housing  12 . The cooling medium flows back through the energy delivery apparatus  1  and exits the fluid outlet lumen  20  at the proximal end of the outer housing  12 . During this travel the cooling medium contacts the inner tubular structure  16 , the energy delivery component  2  and the outer housing  12 , thus cooling the inner tubular structure  16 , the energy delivery component  2 , the outer tubular housing  12 , and tissue  46  in contact with the energy delivery apparatus  1 . Accordingly, both the tissue under treatment and the energy delivery apparatus  1  are cooled, minimizing the possibility of damaging energy delivery component  2  and energy delivery apparatus  1 , or overheating adjacent tissue. It should be appreciated that the direction of flow could be reversed with the inlet flow traveling between the outer housing  12  and inner tubular structure  16  and the outlet flow traveling through the lumen of the inner tubular structure  16 . In either method of operation, both the energy delivery component  2 , and tissue  46  in contact with energy delivery apparatus  1  will experience cooling. 
     The temperature or flow rate of the cooling medium may be controlled to provide a desired cooling of tissue or energy delivery component. It is contemplated herein that the cooling medium may flow in a continuous or in an intermittent manner. Modulating supply temperature or flow rate of the cooling medium allows for increased deposition of photon energy by reducing or eliminating damage of tissue in direct contact with energy delivery apparatus  1 , thus leading to development of increased possible lesions sizes. 
     The heat transfer medium may be a cooling medium or a heating medium. Examples of the cooling medium include room temperature and chilled fluids including liquids and gases such as saline solution, water, air, nitrogen, carbon dioxide, alcohols, and other suitable substances. Suitable substances include fluids with a suitable heat capacity or that are transmissive to the wavelength of light emitted from the energy delivery component  2 . In some embodiments, the fluid may also include sealants, coagulants, anti-coagulants, anesthetics, optical agents, radio-opaque agents, dyes, magnetic resonance agents, therapeutic drugs, and chemotherapy agents, among other treatment agents. 
     In one exemplary embodiment, a fluid containing an MRI contrast agent may be used during insertion of the energy delivery apparatus  1 . The cooling fluid may be optionally changed during energy delivery or therapeutic agents may be added at appropriate times during treatment. 
     It is contemplated herein that before, during or after the delivery of energy, induced temperatures may be monitored using MRI-based thermometry. Accordingly, procedures may be conducted for facilitating estimation of thermal damage at the active area of the energy delivery apparatus  1  and furthermore for preventing overheating of energy delivery apparatus  1 , or other tissues in its surrounding area. 
     Cooling tissue in accordance with embodiments of the disclosures made herein permits creation of larger thermal lesions in a safer manner. Cooling of the tissue in contact with energy delivery apparatus  1  limits such tissue from being charred or carbonized by overheating. By limiting the formation of carbonized tissue, forward propagation of photons by direct absorption is not impeded, thus allowing continued lesion growth from volumetric heating by deeper penetration of photons prior to absorption, as opposed to primarily conductive heating as in the case of carbonized tissue. Furthermore, there is a reduced potential for the energy delivery component  2  to overheat and cause damage or destruction of components comprising the energy delivery apparatus  1 . Furthermore, cooling tissue near the interface of energy delivery apparatus, where power density or induced temperature is highest, means that energy may be deposited at a higher rate or in greater quantity without reaching undesirable temperature elevation in tissue. 
     In one exemplary embodiment, energy may be applied at a rate of 8 to 9 watts for a period of 3 to 5 minutes. Lesions of greater than 2 cm diameter may be created quickly in less than 1 minute of treatment, improving the likelihood and efficiency of complete treatment of cancerous lesions or other tissues. Cooling methods in accordance with the disclosures maintain energy delivery apparatuses, such as laser applicators, below threshold temperatures for thermal destruction and providing removal of surface heat, allowing deeper and longer lasting penetration of photons in treated tissue. 
       FIG. 2B  depicts one exemplary application for the CLF apparatus. In this exemplary application, the apparatus is inserted through healthy tissue such as brain tissue and into a tumor  49 . The distal end of the energy delivery component is located within the tumor  49  and energy is transmitted to the diseased tissue. The cooling medium cools the energy delivery apparatus and tissue in contact with the energy delivery apparatus. Alternative embodiments may also permit delivery of therapeutic agents to the diseased tissue. 
       FIG. 3A  depicts an alternative embodiment of the energy delivery apparatus  1  wherein the penetrating tip portion  14  of the outer housing  12  includes a region of light scattering particles  50  embedded within the tip for preventing excessive forward propagation of light from energy delivery component  2 . The region of light scattering is adapted to allow increased power use while preventing high power densities at the distal end of the energy delivery apparatus  1  and can also be used to tailor the shape of the resulting lesion. 
       FIG. 3B  depicts an alternative embodiment of the energy delivery apparatus  1  wherein a reflective component  52  is included within the distal end of the outer housing  12 . The reflective component  52  prevents significant forward propagation and increases photon scattering along the length of the laser delivery component  2  by causing photons which exit the distal end of laser delivery component  2  to be reflected back into the diffusing tip element  3  where their chances for being scattered out along the length of diffusing tip element  3  and into the tissue increase. Use of reflective component  52  may also aid in tailoring the resulting energy distribution emitted along the length of energy delivery apparatus  1  and hence the resulting lesion within the tissue. 
       FIG. 3C  depicts an alternative embodiment of the energy delivery apparatus  1  wherein the outer housing  12  includes perforations  54  along its length. Perforations  54  may provide increased tissue cooling, or alternatively may be used for administration of anesthetics, therapeutic drugs, light absorptive agents, agents that alter the optical properties of the tissue or other fluids. Alternatively, membranes may be incorporated into the housing to allow agents to pass into the tissue. In alternative embodiments, fluid may be extracted from the tissue for testing purposes. 
       FIG. 3D  depicts an alternative embodiment of the energy delivery apparatus  1  wherein the penetrating tip  14  of the outer housing  12  is modified to include one of more distal fluid pathways  56 . The fluid pathway  56  may be optionally opened or closed by retracting or advancing the energy delivery component  2 . The tip of the energy delivery component  2  is designed such that it seals the opening of the distal fluid pathway when advanced into the fluid pathway. 
       FIG. 3E  depicts an alternative embodiment of the energy delivery apparatus  1  wherein the outer housing  12  is provided with a thin non-stick coating  58 . The coating  58  may include one of a number of fluoropolymers or silicones with high temperature handling capability and non-stick surface properties with respect to thermally coagulated tissues. Materials for outer housing  12  can then be chosen based on the desired stiffness of the energy delivery apparatus  1  while the thin coating  58  of fluoropolymer or silicone provides the ideal surface properties. 
       FIG. 3F  depicts an alternative embodiment of the energy delivery apparatus  1  wherein the outer housing  12  and inner tubular structure  16  are constructed with a stepped down diameter at the distal end of the energy delivery apparatus  1 . Accordingly the resistance to flow of the cooling media can be significantly reduced by shortening the length of the energy delivery apparatus that consists of smaller lumen areas for fluid flow. By doing so a significantly smaller diameter for outer housing  12  at the active site for laser delivery can be created allowing penetration into tissues with less force and with less trauma to surrounding normal tissues. 
       FIGS. 3G-3J  depict alternative embodiments in which reflective material  17  is placed around a semi circular section of the outer or inner surface of either the outer housing  12  or inner tubular structure  16 . Any single or combination of the embodiments depicted may be used to preferentially emit energy over an angular region of energy delivery apparatus  1 . 
       FIGS. 4A-4F  depict cross-sections of exemplary embodiments of integrated energy apparatuses.  FIG. 4A  depicts a cross-section of an exemplary embodiment in which the energy delivery component  2 , the structure  16 , and the housing  12  form concentric circular channels.  FIGS. 4B-4F  depict alternative embodiments in which the housing  12  has a shape that is different than the shape of the structure  16 . Each of these embodiments may provide channels that remain open when the housing  12  or structure  16  is flexed. Some embodiments, such as that illustrated in  FIG. 4D , may also provide improved surface area for heat transfer. In other exemplary embodiments, the inside cross-sectional shape of the housing  12  may differ from the outside cross-sectional shape.  FIG. 4G  depicts a further alternative embodiment in which structure  16  is replaced by structural elements of the housing that provide for separate channels,  18  and  20 , when an energy delivery component  2  is inserted. 
       FIGS. 5-7  depict exemplary methods for performing treatment. As illustrated in  FIG. 5 , the energy delivery apparatus is assembled, as illustrated at  502 . For example, the energy delivery component may be inserted into an integrated apparatus that includes the housing, coupling, and tubular structure. The assembly may occur at a manufacturing site or in an operating room just prior to insertion in a patient. This assembly may include insertion of an energy delivery component. The energy delivery component may be coupled to an energy source. The energy delivery apparatus may also be coupled to a heat transfer medium supply. The assembly may occur prior to insertion of the apparatus in the tissue or during manufacturing of the apparatus. The apparatus may be inserted into the tissue, as illustrated at  504 . 
       FIG. 6  depicts an exemplary treatment method. The energy delivery apparatus is located proximate to the tissue to be treated, as illustrated at  602 . For example, the tissue may be a tumor and the distal end of the energy delivery apparatus may be located within the tumor or around the tumor. In the exemplary embodiment illustrated in  FIG. 2B , once the skull is accessed, the energy delivery apparatus may be inserted into the soft tissue of the brain without a guide or catheter. Alternatively, for tough tissues, a guide or catheter may be utilized. Heat transfer medium, such as a coolant, may be provided to the integrated energy delivery apparatus, as illustrated at  604 . Energy may be provided to an energy delivery component for delivery to the tissue, as illustrated at  606 . In one exemplary embodiment, a radial diffusive tip may be located within the tumor and may be used to disperse photons in a 360 degree pattern. In an alternative embodiment, an angular spread of photons may be provided to tissue using a directed tip located outside the tumor. The heat transfer medium may be provided in conjunction with the energy. 
       FIG. 7  depicts another exemplary treatment method. The energy delivery apparatus receives a heat transfer medium, as illustrated at  702 . The heat transfer medium, for example, may be a room-temperature saline coolant. Alternatively, the heat transfer medium may be heated. The heat transfer medium may pass through the two channels of the integrated energy delivery apparatus. The heat transfer medium is provided from the energy delivery apparatus, as illustrated at  704 . The heat transfer medium may be recirculated or sent to a waste receptacle. Energy may be received by the energy delivery apparatus, as illustrated at  706 . The energy may be received concurrently with the heat transfer medium. 
     Example 
     In one exemplary embodiment, a cooled laser applicator in accord with the disclosure was constructed to house a fiber optic energy delivery component having a diffusing tip, a 400·mu·m fiber optic core, and a 700·mu·m outer diameter and to allow circulation of room-temperature cooling fluid at a rate of approximately 15 mL/minute. The cooled laser applicator and internal fiber optic were used in conjunction with a 980 nm wavelength laser energy source to produce thermal lesions in volumes of beef myocardium. For comparison, an identical diffusing tip fiber optic laser applicator was also used without a cooling apparatus. 
     Using un-cooled diffusing tips, power levels of 6 and 7 W resulted in failure (burning) of the tip before the end of a 5-minute dose period. At 8 W, fiber failure was immediate. In contrast, no failures were observed using the cooled diffusing applicator at powers up to 10 W for up to 8 minutes. Further, while significant char resulted in two of the un-cooled lesions, only the largest water-cooled dose resulted in char formation, which was minimal and not in contact with the applicator. Lesion dimensions increased with dose, but for un-cooled fibers, did not increase with power due to premature tip failure. In the cooled case, lesion dimensions increased monotonically with dose. 
     While the above exemplary embodiments depict a cooling system and cooling medium, a heating system and heating medium may alternatively be used. In general, a heat transfer medium may be used as fluid transferred through the channels. 
     Particular embodiments of the integrated apparatus provide advantageous technical features. For example, use of an integrated apparatus permits construction of the apparatus with smaller cross-section components and thinner wall structures. In particular, such construction reduces damage tissue surrounding the treated area and permits improved energy transmission beyond that achievable by the state of the art. 
     Aspects of the disclosure are found in an integrated apparatus for delivering energy to a tissue. The integrated apparatus includes a housing having a distal end and a tubular structure located within the housing forming a first annulus between the tubular structure and the housing. The tubular structure is configured to accept an energy delivery component and is configured to form a second annulus between the tubular structure and the energy delivery component. The first annulus and the second annulus are configured to communicate with each other proximate to the distal end of the housing. 
     Further aspects of the disclosure are found in an integrated apparatus for delivering energy to a tissue. The integrated apparatus includes a housing having a distal end, a coupling assembly, and a tubular structure. The coupling assembly interfaces with the housing opposite the distal end. The coupling assembly includes a first fluid access port and a second fluid access port. The first fluid access port is associated with a first annulus and the second fluid access port is associated with a second annulus. The coupling assembly includes an opening for introducing an energy delivery component. The tubular structure is located within the housing, forming the first annulus between the tubular structure and the housing. The tubular structure is configured to form the second annulus between the tubular structure and the energy delivery component. The first annulus and the second annulus are configured to communicate with each other proximate to the distal end of the housing. 
     Additional aspects of the disclosure are found in an energy delivery system. The energy delivery system includes an energy source, a heat transfer fluid source and an integrated apparatus. The integrated apparatus includes a housing having a distal end and a tubular structure located within the housing forming a first annulus between the tubular structure and the housing. The tubular structure is configured to accept an energy delivery component and is configured to form a second annulus between the tubular structure and the energy delivery component. The first annulus and the second annulus are configured to communicate with each other proximate to the distal end of the housing. 
     Additional aspects of the disclosure are found in an integrated apparatus. The integrated apparatus includes a housing having a distal end having a penetrating portion. The housing is configured to accept a waveguide internal to the housing. The housing includes a first channel and a second channel internal to the housing. The first channel and the second channel are configured to communicate with each other proximate to the distal end and isolated from each other proximate to an end opposite the distal end. 
     Further aspects of the disclosure are found in an integrated apparatus for delivering energy to a tissue. The integrated apparatus includes a housing having an energy delivery end, a first channel portion located internal to the housing and configured to direct coolant flow toward the energy delivery end, and a second channel portion located internal to the housing and configured to direct coolant flow away from the energy delivery end. 
     Aspects of the disclosure are also found in a method of interstitial thermal therapy. The method includes receiving a heat transfer medium at an intake portion of an integrated energy delivery apparatus from a source external to the integrated energy delivery apparatus; providing the heat transfer medium from an output region of the integrated energy delivery apparatus to a destination external to the integrated energy delivery apparatus; and receiving energy at a proximal end of an energy delivery component. The energy delivery component has a distal end internal to the integrated energy delivery apparatus and terminates proximate to a distal end of the integrated energy delivery apparatus. 
     Further aspects of the disclosure are found in a method for delivering energy to a tissue. The method includes locating an integrated apparatus proximate to the tissue; providing transfer fluid via the first annulus and the second annulus to exchange heat with the energy delivery apparatus; and providing energy to the tissue via the energy delivery component. The integrated apparatus includes a housing having a distal end and a tubular structure located within the housing forming a first annulus between the tubular structure and the housing. The tubular structure is configured to accept an energy delivery component and is configured to form a second annulus between the tubular structure and the energy delivery component. The first annulus and the second annulus are configured to communicate with each other proximate to the distal end of the housing. 
     Additional aspects of the disclosure are found in a method of performing interstitial thermal therapy. The method includes inserting an integrated energy delivery apparatus into a tissue and delivering energy via an energy delivery component to the tissue. The integrated energy delivery apparatus includes a housing including a first fluid channel internal to the housing and a second fluid channel internal to the housing. The housing is configured to accept an energy delivery component internal to the housing. 
     Aspects of the disclosure are also found in a method of interstitial thermal therapy. The method includes assembling an integrated energy delivery apparatus and providing the integrated energy delivery apparatus for insertion into a tissue. The integrated energy delivery apparatus includes a housing including a first fluid channel internal to the housing and a second fluid channel internal to the housing. The housing is configured to accept an energy delivery component internal to the housing. 
     Further aspects of the disclosure are found in an energy delivery apparatus having an outside diameter less than 1.5 mm. 
     The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments that fall within the true scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.