Abstract:
A system for extending the visual capabilities and working channel of a bronchoscope including a probe having optic and/or tracking capabilities at a distal tip thereof and capable of being advanced through the working channel of a standard bronchoscope. The probe also includes a working channel through which various diagnostic and treatment tools may be advanced.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a divisional of U.S. patent application Ser. No. 12/501,330 filed Jul. 10, 2009 entitled Integrated Multi-Functional Endoscopic Tool, which claims benefit of U.S. Provisional Application Ser. No. 61/079,678, filed Jul. 10, 2008 entitled Integrated Multi-Functional Endoscopic Tool; both of which are incorporated herein by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Identifying and treating lung tissue abnormalities presents challenges that are somewhat unique to the lungs. If a tissue lesion or tumor is to be identified and excised surgically, the chest wall must be opened to provide access to the lungs. Opening the chest wall is a common procedure but one that presents risks of infection and lengthy recovery time, nonetheless. If a tissue lesion or tumor is to be identified endoscopically, the complicated bronchial maze must be navigated. 
         [0003]    Bronchoscopes are small cameras attached to the end of a navigable probe and are useful in navigating the airways. The live, illuminated images provide the physician a direct look at the inside surfaces of the airways; however, these bronchoscopes have some inherent shortcomings. First, their present size limits how far into the airways they can be navigated. The airways decrease in diameter as the alveoli are approached. Second, the lungs are a moist environment and can cause the camera lens to become obscured with moisture. Similarly, if a tissue procedure, such as a biopsy, is performed in an airway that can accommodate an endoscope and a cutting tool, there is a chance that blood, mucous, or tissue may land on the lens and obscure the physician&#39;s view. 
         [0004]    To address the first shortcoming, technology has been developed that allows a physician to track, in real-time, the position of a probe (hereinafter “locatable guide” or “LG”) traveling through the airways. This technology incorporates a plurality of coils at the end of an LG and a magnetic field generator outside of the patient. The patient is placed in the magnetic field created by the generator. As the LG is navigated through the airways, electrical current is induced in the coils and sent via conductors to a computer. The computer can calculate the position and orientation of the probe based on the relative strengths of the current being induced. This technology is shown and described in greater detail in U.S. Pat. Nos. 7,233,820 6,226,543, 6,188,355, 6,380,732, 6,593,884, 6,711,429, 6,558,333, 6,887,236, 6,615,155, 6,574,498, 6,947,788, 6,996,430, 6,702,780, and 6,833,814; and U.S. Patent Publications 20050171508, 20030074011, 20020193686, each of which is incorporated by reference herein in its entirety and also PCT application WO 03/086498 titled ‘Endoscope Structure and Techniques for Navigation in Brunched Structure’ to Gilboa, fully incorporated herein by reference. 
         [0005]    These references describe a method and apparatus in which a thin locatable guide, enveloped by a sheath, is used to navigate a bronchoscopic tool to a target location within the lung, aimed in particular to deliver treatments to the lung periphery beyond the bronchoscope&#39;s own reach. The coordinates of the target are predetermined based upon three-dimensional CT data. A location sensor is incorporated at the locatable guide&#39;s tip. The enveloped guide is inserted into the lung via the working channel of a bronchoscope. First, the bronchoscope&#39;s tip is directed to the furthest reachable location in the direction of the target. Next, the guide is advanced beyond the tip of the bronchoscope towards the designated target, based on the combination of the CT data and the position of the guide&#39;s tip as measured in body coordinates. When the guide&#39;s tip is at the target, the guide is withdrawn, freeing the sheath for insertion of a bronchoscopic tool. In order to prevent the distal end portion of the sheath from sliding away from the target, the sheath is locked to the bronchoscope&#39;s body and the bronchoscope itself is held steadily to prevent it from slipping further into the lungs or outwards. Because the airways in the periphery of the lung are narrow, approximately in the same dimensions as the sheath, sideways movements are extremely limited. 
         [0006]    The above system and apparatus are aimed to navigate standard bronchoscopic tools to a target located in the lung. In its basic operation, first the target is identified in the CT data, then the guide is navigated to the target and a medical treatment is delivered. It would be advantageous, however, to perform more sophisticated treatments, such as by combining different types of treatments into a single session. Because these locatable guides are smaller than endoscopes, they can travel deeper into the airways. Additionally, rather than relying on visible landmarks and the physician&#39;s knowledge of the anatomy of the airways, the position of the LG is superimposed on a computer rendering or x-ray image of the lungs, thereby increasing the navigation value of the sensor. Advantage may be taken of both technologies by placing a probe within a working channel of the endoscope. Thus, real-time images may be viewed while navigating the endoscope as far into the airways as its size allows. Then, the LG is advanced out of the distal end of the working channel of the bronchoscope and deeper into the airways. The LG is surrounded by a sheath. In some embodiments the sheath is steerable and in others, the LG itself is steerable. 
         [0007]    Once the LG has been navigated to a target area, presently the LG is retracted through the sheath, while the sheath is left in place. The sheath is referred to as an “extended working channel” (“EWC”) because it is effectively an extension of the working channel of the bronchoscope. The EWC is then used as an avenue for inserting working tools to the target site. Such tools include biopsy needles, ablation devices, etc. After the LG is removed from the EWC, the physician is operating blind, relying on the EWC to remain fixed at the target site. If a tool, such as an aspiration needle or an ablation tool, is being used that requires repositioning in order to treat a greater target area, the repositioning must be done without guidance. 
         [0008]    There is a need for an apparatus that allows a physician to operate on a target site endoscopically, while benefiting from the concurrent use of a bronchoscope, an LG, or both. There is a further need for an endoscopic tool that has the capability of maintaining a clear lens during a procedure in a moist environment. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention represents a step forward in endoscopic procedures by providing an endoscopic tool that is capable of being inserted into narrow passageways and performing procedures once a target has been reached. Preferably the instrument of the present invention is insertable through the working channel of a standard bronchoscope. 
         [0010]    More specifically, the present invention is a catheter designed to be extended out of the distal end of the working channel of a bronchoscope. The catheter includes a micro-camera with a means for cleaning the lens thereof in situ. Additionally, the catheter includes a location sensor capable of either transmitting a location signal or detecting location fields such that location and orientation data may be provided to the practitioner. 
         [0011]    Additionally, the catheter of the present invention includes one or more miniature working channels capable of receiving diagnostic and therapeutic tools and catheters, such as biopsy or ablation tools and catheters. Other examples of diagnostic and therapeutic tools for use with the device of the present invention include various needles, forceps, guide catheters, cyrocatheters, needle aspiration catheters, modified athereoctomy devices, just to name a few. The combination of the camera, the miniature working channel, and the sensor, provides the practitioner with a real-time view of the tissue being manipulated during the procedure. The practitioner also has an unprecedented degree of confidence that the tissue being manipulated is the targeted tissue. 
         [0012]    One aspect of the present invention uses the devices of the present invention for applications such as integrated in situ diagnostic techniques (AF, ULS, OCT, etc.), delivering pre-therapy tools to direct subsequent therapeutic procedures such as markers to guide radiosurgery or inject dye to direct VATS procedures, therapeutic delivery such as LDR brachy seeds or site-specific drug delivery. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a general embodiment of the device of the present invention; 
           [0014]      FIG. 2  is a diagram of the basic components of an embodiment of the location system of the present invention; 
           [0015]      FIG. 3  is an elevation of an embodiment of a sensor assembly of the present invention; 
           [0016]      FIG. 4A  is a perspective view of an embodiment of a sensor assembly of the present invention; 
           [0017]      FIG. 4B  is a circuit diagram of the sensor assembly of  FIG. 4A ; 
           [0018]      FIG. 5  is a perspective view of an embodiment of a sensor assembly of the present invention; 
           [0019]      FIG. 6  is an exploded view of an embodiment of a location board of the present invention; 
           [0020]      FIG. 7  is a perspective view of an embodiment of an optic system of the present invention; 
           [0021]      FIG. 8  is an elevational cutaway view of a distal tip of an embodiment of the catheter of the present invention; 
           [0022]      FIG. 9  is a perspective view of an embodiment of an optical cleaning system of the present invention; 
           [0023]      FIG. 10  is a perspective cutaway view of a distal tip of an embodiment of the catheter of the present invention; 
           [0024]      FIG. 11  is a perspective view of a distal tip of an embodiment of the catheter of the present invention; 
           [0025]      FIG. 12  is a plan view of an embodiment of a tool of the present invention; 
           [0026]      FIG. 13  is a plan view of an embodiment of a tool of the present invention within an embodiment of a catheter of the present invention; 
           [0027]      FIG. 14  is a plan view of an embodiment of a tool of the present invention within an embodiment of a catheter of the present invention; 
           [0028]      FIG. 15  is a cutaway perspective view of an embodiment of a distal tip of a catheter of the present invention; 
           [0029]      FIG. 16  is a perspective view of an embodiment of a steering system of the present invention; 
           [0030]      FIG. 17  is a perspective view of an embodiment of a distal tip of a catheter of the present invention; 
           [0031]      FIG. 18  is a see-through view of an embodiment of a distal tip of a catheter of the present invention; 
           [0032]      FIG. 19  is a close up of a portion of the distal tip of the catheter shown in  FIG. 18 ; 
           [0033]      FIG. 20  is a close up of a portion of an embodiment of a distal tip of a catheter of the present invention; 
           [0034]      FIG. 21  is a comparison of the bending radius of two catheters having different rigid tip lengths; 
           [0035]      FIG. 22  is an elevation view of several embodiments of distal tips of catheters of the present invention juxtaposed to compare sizes; 
           [0036]      FIG. 23  is an end view of several embodiments of distal tips of catheters of the present invention juxtaposed to compare sizes; 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    Referring now to  FIG. 1 , there is shown a general embodiment of the catheter  10  of the present invention. The embodiment in  FIG. 1  is described as “general” because it is being used as a platform to introduce the various aspects and components of the present invention, which will then be discussed separately in more detail. Hence,  FIG. 1  shows that the catheter  10  is sized to extend from the distal end of a working channel of a standard bronchoscope A. For example, some common bronchoscopes have working channels with an internal diameter of about 2.8 mm, while others have working channels with an internal diameter of about 2.65 mm. Hence, the catheter  10  has an outside diameter of 2.8 mm, or slightly less, or preferably 2.65 mm, or slightly less, such that is slides freely within the working channels of these bronchoscopes A. The catheter  10  generally includes a working channel  20 , a location system  100  (only a component of which is shown in  FIG. 1 ), an optical system  200 , an optic cleaning system  300 , a tool  400 , a steering mechanism  500 , and a catheter body  600 . It is to be understood that the catheter  10  of the present invention is considered to be any device containing one or more of these features, in any of their respective variations discussed below, in any combination. These components are being described individually specifically so as not to limit the scope of the present invention to one or more combinations of these features. One skilled in the art will quickly realize that the number of components of the catheter  10 , each described in various forms below, would result in too many combinations to practically describe individually. 
         [0038]    Location System  100   
         [0039]    The location system  100 , shown in  FIGS. 2-X , generally includes a sensor assembly  120 , a location board  140 , and a control system  180 . 
         [0040]    The sensor assembly  120  may be passive or active. A system using a passive sensor assembly  120  is shown in  FIGS. 2-6  and also in U.S. patent application Ser. No. 12/417,381 filed Apr. 2, 2009 entitled Magnetic Interference Detection System and Method, which claims priority to provisional application Ser. Nos. 61/042,191, filed Apr. 3, 2008, and 61/042,578, filed Apr. 4, 2008 entitled Magnetic Interference Detection System and Method, all of which are incorporated by reference herein in their entireties. The sensor assembly  120  of the passive system is a receiver that generally includes a plurality of (preferably three) field component sensors  122 ,  124  and  126 . Each of the field sensor components is arranged for sensing a different component of an electromagnetic field generated by the location board  140 . Alternatively, the field sensor components could use ultrasound technology, or a combination of electromagnetic and ultrasound technologies. 
         [0041]    In one embodiment, shown in  FIGS. 2 and 3 , each field component sensor  122 ,  124  and  126  includes two sensor elements,  122   a ,  122   b ,  124   a ,  124   b ,  126   a , and  126   b , respectively. Typically, the sensor elements are coils of wire, and the sensed components are independent magnetic field components. The coils may be formed by wrapping wire around a core. The core may then be removed to form an air core at the center of the coil or may be left in place, forming a solid core coil. Preferably, the solid core coils are made of a material such as ferrite or another material having similar magnetic properties. 
         [0042]    Preferably, the sensor elements  122 ,  124  and  126  are arranged in the locatable guide  120  such that the sensor elements  122   a  and  122   b  are on opposite sides of, and equidistant from, a common reference point  128 . Similarly, sensor elements  124   a  and  124   b  are on opposite sides of, and equidistant from, point  128 , and sensor elements  126   a  and  126   b  also are on opposite sides of, and equidistant from, point  128 . In the illustrated example, the sensors  122 ,  124  and  126  are disposed collinearly along a longitudinal axis  130  of the sensor assembly  120 , but other configurations are possible. 
         [0043]    For example,  FIG. 4  shows a sensor assembly  120  having field sensor components  122 ,  124  and  126 ′. Field sensor components  122  and  124  each have two sensor elements  122   a  and  122   b , and  124   a  and  124   b , respectively. Sensor elements  122   a  and  122   b  are on opposite sides of, and equidistant from, point  128 . Sensor elements  124   a  and  124   b  are on opposite sides of, and equidistant from, point  128 . However, field sensor component  126 ′ consists of a single coil centered on point  128 . 
         [0044]      FIG. 5  shows an embodiment wherein the field sensor components  122 ,  124  and  126  each include two sensor elements  122   c  and  122   d ,  124   c  and  124   d , and  126   c  and  126   d , respectively. Each sensor element is a flat rectangular coil, of many turns of conducting wire that is bent into an arcuate shape to conform to the shape of the cylindrical surface. The dashed lines  134  and dashed circles  136  in  FIG. 5  denote a conceptual cylindrical surface. The sensor elements  122   c ,  124   c  and  126   c  are interleaved around circle  136   a . The sensor elements  122   d ,  124   d , and  126   d  are interleaved around circle  136   b . The sensor elements  122   c  and  122   d  are preferably disposed symmetrically with respect to the reference point  128 , meaning that sensor elements  122   c  and  122   d  are on opposite side of reference point  128 , are equidistant from reference point  128  and are oriented so that an appropriate 180 degree rotation about point  128  maps sensor  122   c  into sensor  122   d . Similarly, sensor elements  124   c  and  124   d  are disposed symmetrically with respect to reference point  128 , and sensor elements  126   c  and  126   d  are disposed symmetrically with respect to reference point  128 . 
         [0045]    Referring again to  FIG. 2 , the location system  100  also includes the location board  140 . The location board  140  is a transmitter of electromagnetic radiation. The location board  140  includes a stack of three substantially planar rectangular loop antennas  142 ,  144  and  146  connected to drive circuitry  148 .  FIG. 6  provides an expanded view of the loop antennas  142 ,  144  and  146  of the location board  140  in an expanded view to show the details of their configurations. 
         [0046]    Antenna  142  is skewed in a y direction in that the loops on one side of the antenna  142  are closer together than the loops on the opposite side. Hence, antenna  142  creates a magnetic field that is stronger on the side where the loops are close together than it is on the opposite side. By measuring the strength of the current induced by the antenna  142  in the sensor assembly  120 , it can be determined where the sensor assembly  120  is located in a y direction over the antenna  142 . 
         [0047]    Antenna  144  is similarly skewed but in an x direction. Hence, the antenna  144  also creates a magnetic field that is stronger on the side where the loops are closer together than it is on the opposite side. By measuring the strength of the current induced by the antenna  144  in the sensor assembly  120 , it can be determined where the sensor assembly  120  is located in an x direction over the antenna  144 . 
         [0048]    Antenna  146  is not skewed. Rather, it creates a uniform field that naturally diminishes in strength in a vertical direction when the location board is horizontal. By measuring the strength of the field induced in the sensor assembly  120 , it can be determined how far the locatable guide is located above the antenna  146 . 
         [0049]    In order to distinguish one magnetic field from another, the fields of each antenna  142 ,  144  and  146  are generated using independent frequencies. For example, antenna  142  might be supplied with alternating current oscillating at 2.5 kHz, antenna  144  might be supplied with alternating current oscillating at 3.0 kHz, and antenna  146  might be supplied with alternating current oscillating at 3.5 kHz. Hence, each of the field sensors  122 ,  124 , and  126  of the locatable guide will have three different alternating current signals induced in its coils. 
         [0050]    Driving circuitry  148  includes appropriate signal generators and amplifiers for driving each of the loop antennas  142 ,  144  and  146  at their corresponding frequencies. The electromagnetic waves generated by the location board  140  are received by the sensor assembly  120  and converted into electrical signals that are then sent to the control system  180 , shown diagrammatically in  FIG. 2 . 
         [0051]    The control system  180  generally includes reception circuitry  182  that has appropriate amplifiers and ND converters. The reception circuitry  182  and the driving circuitry  148 , which may be considered part of the control system  180 , are controlled by a controller/processor  184  that typically is an appropriately programmed computer. The controller/processor  184  directs the generation of transmitted signals by driving circuitry  148 . 
         [0052]    A location system  100  using an active sensor assembly  120  is shown and described in U.S. Pat. No. 6,188,355 to Gilboa, entitled Wireless Six-Degree-of-Freedom Locator. The entirety of the patent is incorporated by reference herein. The principles of operation are similar to the operation of the passive sensor assembly system except that electrical current is sent to the sensor assembly  120 , such that magnetic fields are generated thereby. These magnetic fields are then detected by other sensors and that information is used to determine a location of the probe in which the sensor assembly  120  is located. 
         [0053]    Optic System  200   
         [0054]    Referring to  FIGS. 7 and 8 , the optic system  200  generally includes an objective lens  210  and one or more light sources  220 , all preferably contained under a sealed optic window  240 . The optic system  200  may operate within or outside of the visible spectrum. As an example only, the optic system  200  may be an infrared system. If an optic cleaning system  300 , described below, is to be used, it may be preferably to make the optic window  240  flush with the distal end of the catheter  10 , thereby increasing the effectiveness of the cleaning system  300 . 
         [0055]    If, however, a wide-angle view is desired, there may be utility in providing a convex optic window  240  that protrudes from the distal tip  30  of the catheter  10 . This may allow the lens  210  to be closer to, or beyond the distal tip  30  of the catheter body. 
         [0056]    The objective lens  210  may be borrowed from existing technology such as a CMOS, fiberscope or a microvideo system. The lens  210  may also be a hybrid between fiberscope and video technology, such as that found on the Olympus BF type XP160F, also marketed as the Evis Exera Bronchofibervideoscope (hereinafter “Olympus scope”). 
         [0057]    The Olympus scope includes a 1.2 mm working channel for a tool but, unlike the present invention, does not have an optical cleaning system, does not have a location system, and does not fit within a 2.65 mm working channel. The Olympus scope has an outside diameter of 2.8 mm. 
         [0058]    Nevertheless, the lens system of the Olympus scope may have application in the catheter of the present invention. The Olympus scope uses a single, relatively large, light source. The present invention provides a plurality of individual, very small fibers, each acting as light guides  220  to illuminate the target. By providing a plurality of small light sources  220 , rather than one larger light source, more space-saving options become available and it is possible to reduce the overall diameter of the catheter  10 . 
         [0059]    The light fibers  220  terminate at a floor  230  of the optic system  200 . A space between the floor  230  and the optic window  240  provides room for additional components  250  and also results in an internal sidewall  260  surrounding the floor  230 . In one embodiment, this sidewall includes a reflective material, which acts to maximize the amount of light being transmitted through the optic window  240 . 
         [0060]    As best seen in  FIG. 8 , the optic system  200  has a relatively short axial length. This leaves room immediately below (proximal) the optic system  200  for the sensor assembly  100 . The light fibers  220  have room around the outside of the sensor assembly  100  to travel the length of the catheter for connection to a light source (not shown). 
         [0061]    Optic Cleaning System  300   
         [0062]    The optic cleaning system  300  is shown generally in  FIG. 9 . The optic cleaning system  300  includes a nozzle  310  located at the distal tip  30  of the catheter  10  and directed toward the optic window  240 . The nozzle  310  is supplied via a lumen with a pressurized liquid or gas. The nozzle directs a stream  320  of the pressurized liquid or gas onto the optic window  240  in order to mechanically remove and/or chemically clean mucous, blood, tissue or other debris from the optic window  240 . The liquid or gas may be any liquid or gas that can be absorbed by the lungs or exhaled without harming the patient. Liquids may include water, saline, and the like. Gases may include oxygen, nitrogen, helium, air, and the like. 
         [0063]    Preferably, the optic cleaning system  300  is fed by a small supply of liquid or gas that is located in a portion of the catheter system  10  that remains outside of the patient, such as the handle. Similarly, locating the valve associated with the actuating system near the supply, as opposed to near the nozzle  310 , will reduce the amount of space occupied by the cleaning system  300 . If, on the other hand, space along the length of the catheter  10  is in short supply, but there is room for a small reservoir at the tip  30  of the catheter, it is envisioned that a reservoir and valve mechanism be located at the tip  30  and electrically controlled by a small wire running the length of the catheter  10 , obviating the need for a supply lumen. 
         [0064]    Tool  400   
         [0065]    The catheter  10  includes a working channel  20 , preferably having an outside diameter of about 1.2 mm, that can accommodate a tool  400 . The tool  400  may be any endoscopic tool, such as forceps, graspers, brushes, markers, seeds, ablation tools, and the like. By way of example only, several embodiments of a tool  400  are discussed in greater detail herein. 
         [0066]    Referring now to  FIGS. 10-14 , there is shown a needle embodiment of the tool  400 . This tool  400  includes a needle tip  410  attached to the distal end of a flexible tube  420 . The flexible tube  420  may then be attached to the distal end of a larger flexible tube  430 . This arrangement creates a shoulder  440  between the tubes  420  and  430 , which can be used as a stop that limits the extent to which the needle tip  410  may be extended from the distal end of the catheter  10 . 
         [0067]    The example shown in  FIG. 12  includes a needle tip  410 , which is a 20 gauge needle having an outside diameter of approximately 0.9 mm. The length of the needle tip  410  is approximately 19 mm. It is understood that the length of the needle tip  410  should be selected considering the task the needle tip  410  is to be given as well as the target location. Because the needle is generally inflexible, a longer needle tip  410  will result in a longer inflexible tip portion  30  of the catheter  10 , which in turn hampers the navigability of the catheter  10 . 
         [0068]    The flexible tube  420  may be made of any suitable, biocompatible material having a desired amount of flexibility and axial strength. A material selected for the embodiment of  FIG. 12  is transparent nylon. The outside diameter of flexible tube  420  preferably matches the outside diameter of the needle tip  410 . The length of the flexible tube  420  is selected to place the shoulder  440  in a desired position to interact with a stop  450  ( FIGS. 13 and 14 ) and result in a desired maximum extension length of the needle tip  410 . It is envisioned that the flexible tube  420  may have a friction fit with the larger flexible tube  430  such that the effective length of the flexible tube  420  may be adjusted for a given procedure by sliding the flexible tube  430  into or out of the larger flexible tube  430  prior to the procedure. 
         [0069]    The larger flexible tube  430  of this embodiment is a PEEK tube with an outside diameter of 1.15 mm and extends to the handle of the bronchoscope. The difference in outside diameter of the flexible tube  420  (in this example, 0.9 mm) and the outside diameter of the larger tube  430  (in this example, 1.15 mm) results in the shoulder  440 . Hence, in this example, the shoulder  440  has a height of 0.125 mm. 
         [0070]      FIGS. 13 and 14  show the tool  400  in retracted and extended positions, respectively. In the retracted position of  FIG. 13 , the needle tip  410  is completely contained within the working channel  20  of the catheter  10 . A separation exists between the shoulder  430  and a needle stop  450  within the working channel  20 . 
         [0071]    In the extended position of  FIG. 14 , the needle tip  410  protrudes beyond the distal tip  30  of the catheter  10 . The shoulder  440  abuts against the stop  450 , thereby preventing the needle  410  from being extended further. 
         [0072]    Needle uses are known in the art and are applicable to the needle  410  of the present invention. For example, the needle tip  410 , the flexible tube  420  and the larger flexible tube  430  all have a central lumen which can be made to create one continuous lumen  460  throughout the tool  400 . This lumen  460  can be used to apply suction to the tool  400 , thereby creating an aspirating needle or a biopsy needle. The lumen  460  can also be used as an irrigation port or a means for injecting substances into the target. Alternatively, as shown in  FIG. 11 , a separate irrigation lumen  490  can be provided in catheter  10  to be used in conjunction with aspirating suction applied to the tool  400 . 
         [0073]    If the needle  410  is to be used for biopsy purposes, one skilled in the art will realize that it may be desirable to keep the tissue sample contained within a distal section of the needle  410  for easy retrieval of the sample after the procedure. In this case the needle lumen  460  may be larger than a suction lumen  470 , as seen in  FIG. 11 . Hence, a stop  480  is created that prevents the tissue from traveling too far into the catheter  10 . 
         [0074]    One embodiment of the present invention uses a needle tip  410  or other suitable delivery device to inject one or more markers into the target site. Markers, such as gold markers, can be used as fiducials in an image-guided radiosurgery treatment during interstitial radiation. The insertion of internal fiducial markers into various organs assists in precise setup and real-time tumor tracking during radiotherapy. Markers may also be used to adjust the center of mass of the target volume to a planned position for an upcoming treatment. The markers are visible on x-ray, CT, MR, or other imaging technique and a device that delivers external beam radiation therapy can use the markers to plan and localize radiation delivery. The detection of fiducial gold markers is useful during automatic on-line megavoltage position verification using a marker extraction kernel (MEK). The markers allow for accurate tumor location three-dimensionally throughout the treatment. Alternatively, it is envisioned that the lumen  460  may be used with a pusher to deliver the markers. 
         [0075]    Similarly, the needle  410  can be used to implant seeds for brachytherapy, as one skilled in the art will realize. The added navigation accuracy of the catheter  10  made possible by the combination of the location system  100  and the optic system  200  makes the catheter  10  an ideal vehicle for the precise delivery of brachytherapy seeds. 
         [0076]    Positive results have been obtained using a needle  410  that is an NMPE needle with a three-sided Trocar stylet. This particular needle  410  was made with 18-gauge thin-walled tubing and has an echogenically enhanced tip for use in combination with ultrasonically guided implants. The needle  410  also has an outer cannula chamber for smooth transition. 
         [0077]    Existing seed implant needles may also be used in combination with the present invention. One example of an existing seed implant needle is the Bard BrachyStar® Needle. 
         [0078]    Steering System  500   
         [0079]    The steering system  500  may utilize any combination of retractable wires and/or pre-formed bends. One embodiment of a steering mechanism  500  is shown on the catheter tip  30  of  FIG. 15 . Represented is a cross-section of the distal end of a catheter  10 . The steering mechanism  500  includes a distal housing  510  that contains the location system  100 , defines the distal end of the working channel  20 , and seals the end of the catheter  10 . The distal housing  510  also defines one or more (in this case four) steering wire lumens  520  for receiving steering wires  530 . The steering wire lumens  520  extend the length of the catheter  10  but the portions of the lumens  520  defined by the distal housing  510  are slightly larger to accommodate an anchor ball  540  at the distal ends of the steering wires  530 . At a proximal end of the lumen  520 , the diameter narrows to that of the steering wire  530 , thereby creating a shoulder  550  against which the anchor ball  540  acts when pulled. 
         [0080]      FIGS. 16-19  show a variation on the design of  FIG. 15  in which three steering wires  530  are used instead of four. As seen in  FIG. 17 , the steering mechanism  500  extends from the proximal side of the catheter tip  30  and includes three steering wires  530  spaced 120 degrees apart. 
         [0081]    As shown in  FIGS. 17-19 , rather than extending the steering wire lumens  520  to the distal end of the catheter tip  30 , access ports  525  are provided such that the steering wires  530  may be routed into the sides of the catheter tip  30  and down to the proximal end of the catheter  10 . 
         [0082]      FIG. 20  shows another embodiment of a steering system  500  of the present invention. Here, a manifold  560  is provided that separates the catheter tip  30  from the rest of the catheter  10 . The manifold  560  includes channels  570  that route a steering wire  530  around the periphery of the disk  560  and back toward the proximal end of the catheter. Thus, one steering wire  530  becomes looped and effectively becomes two steering wires. 
         [0083]    Examples of other steering mechanisms that may be used with the catheter  10  of the present invention include, but are not limited to, those discussed in U.S. Pat. No. 6,702,780 to Gilboa et al. 
         [0084]    Catheter Design 
         [0085]    The catheter body  600  is flexible and carries all of the lumens, steering wires, tools, etc. that are employed by the various tip  30  designs of the present invention. Hence, this section will largely consist of a discussion of the various arrangements envisioned by the present invention. Common to all embodiments, is that the body  600  is preferably sized to fit within the working channel of a typical bronchoscope. Notably, however, the minimum bending radius of the body  600 , while inside the working channel of the bronchoscope, is advantageously reduced by a reduced tip  30  length, as shown in  FIG. 21 . 
         [0086]    More specifically,  FIG. 21  shows a comparison between a prior art catheter  1  with a longer tip  2  and a catheter  10  of the present invention with a shorter tip  30 . Both catheters  1  and  10  have the same diameter and are contained within identical working channels  3 . The bending radius is limited by the length of the non-flexible tips  2  and  30 . A shorter tip  30  allows a tighter bending radius. 
         [0087]    Several examples of different configurations of catheters  10  of the present invention are shown in  FIGS. 22-23 . The configurations are juxtaposed adjacent a prior art catheter  1  to show differences in sizes.  FIG. 22  shows elevations of the various catheters while  FIG. 23  shows corresponding end views of the distal tips. 
         [0088]    The prior art catheter  1  has a tip  2  attached to a flexible, steerable segment  4 . The tip  2  is 10.2 mm long and has a diameter that is less than 2.65 mm. However, the location sensor  100  occupies substantially all of the tip  2 . 
         [0089]    Configuration  700  includes a tip  702  attached to a flexible, steerable segment  704 . The tip  702  contains a 19 Ga needle  400 , a sensor  100  and two irrigation lumens  490 , one for irrigation fluid supply and one for applying suction. The tip  702  is 6.8 mm long and the flexible, steerable segment  704  is constructed of a flexible material such as nylon. 
         [0090]    Configuration  710  includes a tip  712  attached to a flexible, steerable segment  714 . The tip  712  contains a 1.2 mm working channel, a sensor  100 , and two looped steering wires  530 . The tip  712  is 6.4 mm long and the flexible, steerable segment  714  is constructed of transparent flexible nylon. 
         [0091]    Configuration  720  includes a tip  722  attached to a flexible, steerable segment  724 . The tip  722  contains a 1.2 mm working channel, a sensor  100 , and four steering wires  530 . The tip  722  is 6.4 mm long and the flexible, steerable segment  724  is constructed of transparent flexible nylon. 
         [0092]    Configuration  730  includes a tip  732  attached to a flexible, steerable segment  734 . The tip  732  contains a 1.2 mm working channel and a sensor  100 , and four access ports  525  containing the distal ends of four steering wires  530 . The tip  722  is 6.4 mm long and the flexible, steerable segment  724  is constructed of transparent flexible nylon. 
         [0093]    Configuration  740  includes a tip  742  attached to a flexible, steerable segment  744 . The tip  742  contains a 1.2 mm working channel with a needle  400  contained therein, a sensor  100 , and four access ports  525  containing the distal ends of four steering wires  530 . The tip  722  is 6.4 mm long and the flexible, steerable segment  724  is constructed of a flexible spring segment. 
         [0094]    Configuration  750  includes a tip  752  attached to a flexible, steerable segment  754 . The tip  752  contains a 1.2 mm working channel, a sensor  100 , four access ports  525  containing the distal ends of four steering wires  530 , an irrigation lumen  490 , an optic system  200 , and an optic cleaning system  300 . The tip  752  is 8.5 mm long to accommodate the optic system  200  and the flexible, steerable segment  754  is constructed of a flexible material such as nylon. 
         [0095]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.