# Patent

## Title
Side-firing fiber delivery device with active cooling cap

## Abstract

A medical laser system and related methods of utilizing cooling within and around an optical fiber tip to prevent premature failure of the optical fiber. The optical fiber is surrounded by a protective jacket assembly including a body tube assembly, and a tip cap assembly. The body tube assembly includes an internal fiber jacket, and an external body tube with a body tube channel defined therebetween. The tip cap assembly includes an inner cap member and an outer cap member defining a cap irrigation channel therebetween. Together, the cap irrigation channel and body tube channel cooperatively define an internal irrigation channel. The optical fiber can be delivered to a treatment location through a cystoscope. Saline is directed through an external irrigation channel between the cystoscope and the protective jacket assembly, as well as the internal irrigation channel to cool the fiber tip and prevent overheating and failure of the optical fiber.

## Background
PRIORITY CLAIM
The present application claims priority to U.S. Provisional Application Ser. No. 60/953,721 filed Aug. 3, 2007, and entitled “Side-Firing Fiber Delivery Device with Active Cooling Cap”, which is hereby incorporated by reference in its entirety.


FIELD OF THE INVENTION
This invention relates to the field of medical lasers utilizing optical fibers. More specifically, the present invention relates to a side-firing optical fiber utilizing internal and external cooling streams to prevent premature failure at a fiber tip.
BACKGROUND OF THE INVENTION
Medical lasers have been used in treatment procedures involving various practice areas, including, for example, urology, neurology, otorhinolaryngology, general anesthetic ophthalmology, dentistry, gastroenterology, cardiology, gynecology, and thoracic and orthopedic procedures. Generally, these procedures require precisely controlled delivery of laser energy, and often the area to which the laser energy is to be delivered is located deep within the body; for example, at the prostate or at the fallopian tubes. Due to the location of the target tissue deep within the body, the medical procedure requires that the optical fiber be flexible and maneuverable. Various light sources can be used with optical fiber devices dependent upon the requirements for the light source; for example, pulsed lasers, diode lasers and neodymium lasers can be used as light sources. Representative lasers used in medical treatment procedures include Ho:YAG lasers and Nd:YAG lasers.
In medical procedures utilizing laser energy, the laser is coupled to an optical fiber adapted to direct laser radiation from the laser, through the fiber and to the treatment area. Typically, a surgical probe is utilized in the treatment of body tissue with laser energy. The surgical probe generally includes an optical fiber coupled to a laser source, and the probe tip is positioned on the optical fiber opposite the laser source, such that the tip of the probe can be positioned adjacent to the targeted tissue. Laser energy is directed out of the probe tip of the optical fiber onto desired portions of the targeted tissue.
Depending upon the operational conditions during laser treatment, a cap on the surgical probe can overheat. Overheating of the cap can lead to failure of the optical fiber. If the optical fiber fails, the laser system fails. Overheating of the cap can cause the cap to burn, detach, or even shatter during treatment inside the patient, which can lead to injury to the patient.
SUMMARY OF THE INVENTION
The present invention comprises a medical laser system and related methods of utilizing cooling within and around an optical fiber tip so as to prevent premature failure of the optical fiber. The optical fiber comprises an internal fiber jacket having a fiber tip for directing laser energy from the optical fiber. The optical fiber is generally surrounded by a body tube and a tip cap assembly. The tip cap assembly generally comprises an inner cap member and an outer cap member. The outer cap member includes a side port positioned within an exterior surface. An internal irrigating channel is defined between the inner cap member and the outer cap member. The optical fiber is generally configured for insertion through a cystoscope such that the fiber tip can be positioned proximate a treatment location. Once the fiber tip is properly positioned, saline can be directed through the irrigating channel, as well as between the cystoscope and the exterior surface to cool the optical fiber and prevent overheating and subsequent failure of the optical fiber. In addition, the use of the outer cap member provides a barrier between the fiber tip and treatment location so as to prevent adhesion of ablated tissue to the fiber tip.
In one aspect, the present invention is directed to an optical fiber having a tip cap assembly defining an internal irrigation channel. The optical fiber can be configured for insertion into a cystoscope, wherein saline can be simultaneously directed through the internal irrigation channel and between the cystocope and an exterior surface of the tip cap assembly. By continually circulating saline both internally and externally of the fiber tip, overheating of the fiber tip is prevented so as to prevent premature failure of the optical fiber.
In another aspect, the present invention is directed to a method for preventing overheating of an optical fiber. The method comprises providing an optical fiber having an internal irrigation channel at a fiber tip. The method further comprises circulating saline through the internal irrigation channel to remove heat energy from the fiber tip. The method further comprises circulating a cooling saline between a cystoscope and an exterior surface of the fiber tip. The method can further comprise providing a physical barrier between a discharge portion of the optical fiber and the treatment location to prevent adhesion of ablated tissue to the optical fiber.
In yet another aspect, the present invention is directed to a medical laser treatment system comprising a laser unit and an optical fiber capable of being introduced to a treatment location with a cystoscope. A fiber tip of the optical fiber is capable of being cooled simultaneously with an external cooling stream between the cystoscope and protective jacket assembly, as well as through an internal irrigation channel defined by a tip cap assembly.
The above summary of the various representative embodiments of the invention is not intended to describe each illustrated embodiment or every implementation of the invention. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the invention. The figures in the detailed description that follows more particularly exemplify these embodiments.



BRIEF DESCRIPTION OF THE DRAWINGS
These as well as other objects and advantages of this invention, will be more completely understood and appreciated by referring to the following more detailed description of the presently preferred exemplary embodiments of the invention in conjunction with the accompanying drawings of which:
FIG. 1 is a block diagram illustration of a laser system according to an embodiment of the present invention.
FIG. 2 is a perspective end view of an optical fiber according to an embodiment of the present invention.
FIG. 3 is a section view of the optical fiber of FIG. 2.
FIG. 4 is a section view of the optical fiber of FIG. 2 being introduced to a treatment location with a cystoscope according to an embodiment of the present invention.
FIG. 5 is a graph comparing percentage of transmission of a optical fiber (2090 fiber) to an optical fiber with the active cooling cap of the present invention.



While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives.
DETAILED DESCRIPTION OF THE DRAWINGS
The present invention comprises an optical fiber for use with a medical laser system that utilizes internal and external cooling streams and related methods of monitoring an optical fiber to determine if an optical fiber cap on the optical fiber is in imminent danger of cap failure. The laser system includes a photodetector for converting returned light from the optical fiber cap to an electronic signal for comparison to a trigger threshold value known to be indicative of imminent fiber cap failure. The returned light can be the main laser treatment wavelength, an auxiliary wavelength, such as an aiming beam, or infrared wavelengths generated by a temperature of the optical fiber cap. In the event the electronic signal reaches the trigger threshold value, the laser system can be temporarily shut-off or the power output can be reduced. In one preferred embodiment, the present invention can be utilized as part of a Greenlight HPS system manufactured by American Medical Systems of Minnetonka, Minn. and as described in U.S. Pat. Nos. 6,554,824 and 6,986,764, which are herein incorporated by reference.
Referring to FIG. 1, there is depicted a block diagram showing an exemplary laser system 100, which may be employed for implementing the present invention. Laser system 100 includes a solid-state laser unit 102, which is used to generate laser light for delivery through optical fiber 106 to target tissue 104. Laser unit 102 is capable of being operated in a pulsed mode or continuous wave.
Laser unit 102 more specifically comprises a laser element assembly 110, pump source 112, and frequency doubling crystal 122. In the preferred-embodiment, laser element assembly 110 outputs 1064 nm of light, which is focused into frequency doubling crystal 122 to create 532 nm of light. According to one implementation, laser element assembly 110 may be a neodymium doped YAG (Nd:YAG) crystal, which emits light having a wavelength of 1064 nm (infrared light) when excited by pump source 112. Laser element assembly 110 may alternatively be fabricated from any suitable material wherein transition and lanthanide metal ions are disposed within a crystalline host (such as YAG, Lithium Yttrium Fluoride, Sapphire, Alexandrite, Spinel, Yttrium Orthoaluminate, Potassium Gadolinium Tungstate, Yttrium Orthovandate, or Lanthanum Scandium Borate). Laser element assembly 110 is positioned proximal to pump source 112, and may be arranged in parallel relation therewith, although other geometries and configurations may be employed.
Pump source 112 may be any device or apparatus operable to excite laser element assembly 110. Non-limiting examples of devices which may be used as pump source 112 include: arc lamps, flashlamps, and laser diodes.
A Q-switch 114 disposed within laser unit 102 may be operated in a repetitive mode to cause a train of micropulses to be generated by laser unit 102. Typically the micropulses are less than 1 microsecond in duration separated by about 40 microseconds, creating a quasi-continuous wave train. Q-switch 114 is preferably of the acousto-optic type, but may, alternatively, comprise a mechanical device such as a rotating prism or aperture, an electro-optical device, or a saturable absorber.
Laser unit 102 is provided with a control system 116 for controlling and operating laser unit 102. Control system 116 will typically include a control processor which receives input from user controls (including but not limited to a beam on/off control, a beam power control, and a pulse duration control), and processes the input to accordingly generate output signals for adjusting characteristics of the output beam to match the user inputted values or conditions. With respect to pulse duration adjustment, control system 116 applies an output signal to a power supply (not shown) driving pump source 112 which modulates the energy supplied thereto, in turn, controlling the pulse duration of the output beam. Laser unit 102 further includes an output port 118 couplable to a proximal end 119 of optical fiber 106. Output port 118 directs the light generated by laser unit 102 into optical fiber 106 for delivery to tissue 104.
Although FIG. 1 shows an internal frequency doubled laser, it is only by way of example. The infrared light can be internally or externally frequency doubled using non-linear crystals such as KTP, Lithium Triborate (LBO), or Beta Barium Borate (BBO) to produce 532 nm of light. The frequency doubled, shorter wavelength light is better absorbed by the hemoglobin and char tissue, and promotes more efficient tissue ablation.
Referring now to FIGS. 2 and 3, optical fiber 200 of the present invention generally comprises an internal fiber 202 defining a fiber tip 204 at a treatment end 205 of the optical fiber 200. Internal fiber 202 is manufactured from a silicon material, typical of optical fibers. Internal fiber 202 is protected from damage prior to use and during introduction to the treatment location with a protective jacket assembly 206. Projective jacket assembly 206 generally comprises a body tube assembly 208 and a tip cap assembly 210. Body tube assembly 208 generally protects a majority portion of the internal fiber 202, extending from proximal end 119 to the tip cap assembly 210. Body tube assembly 208 generally comprise an internal fiber jacket 212, and an external body tube 214 with a body tube channel 216 defined therebetween. Similar to internal fiber 202, internal fiber jacket 212 and external body tube 214 are constructed of a suitable silicon material.
As illustrated in FIG. 3, tip cap assembly 210 generally comprises an inner cap member 218, and an outer cap member 220 defining a cap irrigation channel 222 therebetween. Together, cap irrigation channel 222 and body tube channel 216 cooperatively define an internal irrigation channel 224. Outer cap member 220 includes a side port 226 positioned within an exterior surface 228. Side port 226 generally defines a radiused edge 230, such that laser energy can be directed from the fiber tip 204 to the treatment location.
In operation, optical fiber 200 and, more specifically fiber tip 204, can be introduced to the treatment location utilizing a conventional cystoscope 240, as shown in FIG. 4. Generally, the cystoscope 240 is advanced through the urethra and proximate the treatment area. Once the cystoscope 240 is positioned at the treatment area, an irrigant such as water or saline can be injected through the cystoscope 240. When performing a medical laser procedure with the laser system 100, optical fiber 200 is advanced through the cystoscope 240 such that side port 226 is positioned proximate the desired treatment location.
With the side port 226 oriented toward the treatment location, saline is simultaneously directed through the internal irrigation channel 224, and in an external irrigation channel 242 defined between the cystoscope 240 and the protective jacket assembly 206. With an external cooling stream 244 flowing across exterior surface 228, and an internal cooling stream 246 flowing between the outer cap member 220, and the inner cap member 218, control system 116 directs laser energy through the optical fiber 200 such that a treatment beam exits the fiber tip 204 and out the side port 226. As the treatment beam contacts the treatment location, heat is generated at a tissue surface as the laser energy ablates the targeted tissue. The dual simultaneous cooling of the external cooling stream 244 and the internal cooling stream 246 remove heat energy from the fiber tip 204. As fiber tip 204 is prevented from overheating, ablated tissue is kept from adhering within or around the side port 226, or to the exterior surface 228. In addition, the outer cap member 220 provides a gap between the fiber tip 204 and the treatment location, such that tissue does not attach to the fiber tip 204 due to localized heating at the fiber tip 204. With heat energy removed at the tip cap assembly 210, overheating is avoided such that devitrification and cratering of optical fiber 200 does not occur.
FIG. 5 provides a comparison between the standard 2090 fiber that is typically used with a GreenLight HPS laser treatment device for treatment of benign prostate hyperplasia (BPH) and the fiber with the active cooling cap of the present invention. As shown, the percentage of transmission of light stays steady in the fiber with the active cooling cap, while the 2090 fiber experiences intermittent decreases in transmission of light as energy is increased. As indicated by the graph, the active cooling cap fiber of the present invention provides reduced laser energy absorption by preventing the tissue contact at the laser firing point and the areas adjacent to the firing point; the tissue is in contact with the outer cap rather than the inner cap through which the laser light is being delivered. Further, the irrigation fluid from the inner cap pushes the tissue debris out of the firing point of the inner cap and, hence, further prevents tissue debris from depositing and burning at the firing point. Moreover, the active cooling cap of the present invention can provide cooling from inside of the cap even when the irrigation fluid from the cystoscope is totally blocked by tissue.
Although specific examples have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement calculated to achieve the same purpose could be substituted for the specific examples shown. This application is intended to cover adaptations or variations of the present subject matter. Therefore, it is intended that the invention be defined by the attached claims and their legal equivalents.

## Claims

1. An optical fiber for medical procedures comprising:
an internal fiber terminating at a fiber tip;
a reflective surface that reflects laser energy transmitted through the internal fiber; and
a tip cap assembly comprising:
an inner cap member extending over the reflective surface and including a proximal end on a proximal side of the reflective surface, and a distal end on a distal side of the reflective surface;
an outer cap member extending over the inner cap member and including a distal end on the distal side of the reflective surface attached to the distal end of the inner cap member; and
a cap irrigation channel between the inner cap member and the outer cap member.

2. The optical fiber of claim 1, further comprising a body tube assembly surrounding a portion of the internal fiber and including an internal fiber jacket, an external body tube, and a body tube channel between the internal body tube and the external body tube, wherein the cap irrigation channel and the body tube channel cooperatively define an internal irrigation channel.

3. The optical fiber of claim 2, wherein the body tube assembly and the tip cap assembly are adapted for introduction through a cystoscope, whereupon an internal saline flow can be directed through the internal irrigation channel and an external saline flow can be directed between the cystoscope and the body tube assembly and tip cap assembly to simultaneously cool the fiber tip.

4. The optical fiber of claim 2, wherein the cap irrigation channel and the body tube channel cooperatively define an internal irrigation channel.

5. The optical fiber of claim 1, wherein the outer cap member includes an exterior surface having a side-firing port through which laser energy transmitted through the internal fiber and reflected from the reflective surface is discharged.

6. The optical fiber of claim 5, wherein the outer cap member provides a physical barrier preventing contact between the fiber tip and the treatment location during a treatment procedure.

7. The optical fiber of claim 5, wherein laser energy transmitted through the internal fiber and reflected from the reflective surface is transmitted through the inner cap member.

8. The optical fiber of claim 5, wherein an irrigant flowing through the cap irrigation channel is discharged simultaneously with the laser energy through the side-firing port.

9. The optical fiber of claim 1, wherein the fiber tip comprises the reflective surface.

10. A method for preventing overheating a medical optical fiber during a medical treatment procedure comprising:
providing an optical fiber comprising:
an internal fiber terminating at a fiber tip;
a reflective surface; and
a tip cap assembly comprising:
an inner cap member extending over the reflective surface and including a proximal end on a proximal side of the reflective surface, and a distal end on a distal side of the reflective surface;
an outer cap member extending over the inner cap member and including a distal end on the distal side of the reflective surface attached to the distal end of the inner cap member; and
a cap irrigation channel between the inner cap member and the outer cap member;


directing an internal saline flow stream through the cap irrigation channel;
performing a laser treatment comprising:
transmitting laser energy through the internal fiber;
reflecting the laser energy transmitted through the fiber off the reflective surface; and
discharging the reflected laser energy through the inner cap member; and

removing heat energy generated at the fiber tip during the laser treatment with the internal saline flow stream.

11. The method of claim 10, wherein performing a laser treatment comprises:
accessing an internal treatment site with a cystoscope; and
advancing the optical fiber through the cystoscope such that the fiber tip is proximate the internal treatment site.

12. The method of claim 11, further comprising:
directing an external saline flow stream through a gap defined between the cystoscope and the optical fiber.

13. The method of claim 10, wherein:
the optical fiber comprises a body tube assembly surrounding a proximal portion of the internal fiber and including an internal fiber jacket, an external body tube, and a body tube channel between the internal body tube and the external body tube; and
the method comprises directing an internal saline flow stream through the body tube channel.

14. The method of claim 13, further comprising discharging the reflected laser energy through a side-firing port in the outer cap member.

15. The method of claim 14, further comprising discharging the internal saline flow stream through the side-firing port.

16. A medical laser system comprising:
a laser unit for generating laser treatment energy; and
an optical fiber attached to the laser unit for directing the laser treatment energy to a treatment location, the optical fiber comprising:
an internal fiber terminating at a fiber tip;
a reflective surface that reflects laser energy transmitted through the internal fiber; and
a tip cap assembly comprising:
an inner cap member extending over the reflective surface and including a proximal end on a proximal side of the reflective surface, and a distal end on a distal side of the reflective surface;
an outer cap member extending over the inner cap member and including a distal end on the distal side of the reflective surface attached to the distal end of the inner cap member; and
a cap irrigation channel between the inner cap member and the outer cap member.

17. The medical laser system of claim 16, further comprising:
a cystoscope for accessing a treatment site within a patient's body, the optical fiber adapted for insertion through the cystoscope such that an external saline flow can be directed between the cystoscope and the optical fiber.

18. The medical laser system of claim 16, wherein the optical fiber comprises a body tube assembly surrounding portion of the internal fiber and including an internal fiber jacket, an external body tube, and a body tube channel between the internal body tube and the external body tube.

19. The medical laser system of claim 18, wherein the outer cap member includes an exterior surface having a side-firing port through which laser energy transmitted through the internal fiber and reflected from the reflective surface is discharged.

20. The medical laser system of claim 19, wherein laser energy transmitted through the internal fiber and reflected from the reflective surface is transmitted through the inner cap member.

21. The medical laser system of claim 19, wherein an irrigant flowing through the cap irrigation channel is discharged simultaneously with the laser energy through the side-firing port.

22. The medical laser system of claim 18, wherein the cap irrigation channel and the body tube channel cooperatively define an internal irrigation channel.