Abstract:
An adapter couples a length of optical fiber to a hollow probe and to an optical coherence tomography instrument. The length of optical fiber may be greater than the length of the adapter itself. The optical fiber is fixed to an optical coupler at a proximal end of the adapter and may be maintained in a curved configuration by features located in an internal cavity of the adapter. An optical fiber advance mechanism be used to advance and/or retract the length of optical fiber to align it within the hollow probe.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of application Ser. No. 11/839,517, filed Aug. 15, 2007 now U.S. Pat. No. 7,682,089. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to medical probes. In particular, the invention relates to a system for positioning a medical probe. 
     2. Description of Related Art 
     There are many medical procedures that require the insertion of a probe or needle along a specific path or to a specific location within the human body. The execution of these procedures often relies solely upon the vision and tactile sense of the practitioner. For example, a hypodermic needle may be inserted into the jugular vein of a patient as a prelude to catheritization. Incorrect insertion of a hypodermic needle into the jugular may result in a punctured lung or other complications, thus, a post catheritization X-ray is frequently taken to verify the success of the procedure. 
     Realtime visual information (e.g., ultrasound imaging) regarding internal tissue structures is helpful in avoiding complications during medical procedures; however, realtime imaging techniques may make a procedure significantly more complex. Also, additional personnel or an increased amount of time may also be required. 
     Optical coherence tomography (OCT) is frequently used for realtime imaging and may be integrated with a number of instruments. Such integrated instruments typically require sterilization before reuse and thus are not well suited to high-volume procedures. 
     Thus, a need exists for a system and method for positioning a probe that does not require sterilization before reuse. There is also a need for a system and method for positioning a probe that is suitable for use in high-volume procedures. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides an adapter that couples one or more optical fibers to a hollow probe. The adapter contains a length of optical fiber that is longer than the adapter itself. The optical fiber may be extended into the hollow probe. 
     In one embodiment of the invention the length of optical fiber is fixed to an optical coupler at a proximal end of the adapter and is maintained in a curved configuration by features located in an internal cavity of the adapter. 
     In further embodiment, a conical needle adapter at the distal end of the adapter is configured to accept a hypodermic needle. The conical adapter may have a Luer taper. 
     In another embodiment, a pair of rollers are used to advance the length of optical fiber. The rollers may be composite with a hard core and soft surface, and may also be sealed with in the adapter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a top perspective view of an optical probe adapter in accordance with an embodiment of the present invention. 
         FIG. 1B  shows a top view of the optical probe adapter of  FIG. 1A . 
         FIG. 1C  shows a front view of the optical probe adapter of  FIG. 1A . 
         FIG. 1D  shows a front perspective exploded view of the optical probe adapter of  FIG. 1A . 
         FIG. 1E  shows a back perspective exploded view of the optical probe adapter of  FIG. 1A . 
         FIG. 2A  shows an optical probe adapter with an attached hypodermic needle in accordance with an embodiment of the present invention. 
         FIG. 2B  shows an alignment of an optical fiber at the tip of an attached hypodermic needle in accordance with an embodiment of the present invention. 
         FIG. 3  shows a diagram of a probe positioning system in accordance with an embodiment of the present invention. 
         FIG. 4  shows a flow chart diagram for a method embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1A  shows a top perspective view  100  of an embodiment of an optical probe adapter. The optical probe adapter  100  has a optical fiber coupler  105  at the proximal end and a probe coupler  125  at the distal end. A fiber receiver  110  and cover  115  serve as a handle and also as a housing for an optical fiber, or optical fiber bundle. 
       FIG. 1B  shows a top view  101  of the optical probe adapter of  FIG. 1A . A knob  120  provides a means of advancing or retracting the fiber housed within the optical fiber adapter. The probe coupler  125  has a conical taper  130  that accepts a probe (e.g., hypodermic needle). The conical taper  130  may be a Luer taper. A Luer lock or other interlocking connector may be used in conjunction with the probe coupler  125 . However, since the optical probe adapter is only temporarily coupled to the probe, ease of removal is desired so that the probe position is not perturbed during removal. 
       FIG. 1C  shows a front view  102  of the optical probe adapter of  FIG. 1A . The optical fiber coupler  105  has two optical fiber terminals  140 . In alternative embodiments, the optical fiber coupler  105  may have a greater or lesser number of optical fiber terminals. 
     The optical fiber coupler  105  has two detents  135  that provide a means for locking the coupler into a mated connector. There are many types of optical fiber couplers that may be used. However, most conventional optical fiber adapters are designed for many make-and-break connections. For disposable or single use optical probe adapters, it is preferable that the optical fiber coupler  105  be kept mechanically simple. Any complexity associated with obtaining a reliable connection should reside in the non-disposable component with which the optical coupler  105  may be mated. 
       FIG. 1D  shows a front perspective exploded view  103  of the optical probe adapter of  FIG. 1A . An optical fiber bundle  140  is connected to the optical fiber coupler  105 . In other embodiments, a single fiber may be substituted for the optical fiber bundle  140 . The optical fiber bundle  140  resides in a cavity  145  in the receiver  110 . The cavity  145  has a series of radiused edges  150  that allow the optical fiber bundle to be compactly housed. 
     In general, housing of the optical fiber bundle  140  requires that at least a portion of the optical fiber bundle  140  be stored in a curved configuration. For efficient packing at least one portion will typically have an arc of at least 90 degrees and may have a variable radius. The length of the optical bundle that is ultimately advanced through the probe coupler  125  is derived from the straightening of a curved portion. Although spirals or coils may also be used as housing configurations for the optical fiber bundle  140 , the serpentine configuration shown in  FIG. 1D  has the advantage of avoiding twisting of the fiber during assembly and use. An arc length of 180 degrees is used in the serpentine configuration. 
     The optical fiber  140  is advanced and retracted by a drive roller  160  acting against a pinch roller  170 . The driver roller  160  has a soft outer covering  164  that reduces localized stress in the area of contact with the optical fiber bundle  140 . Similarly, the pinch roller  170  has a soft outer covering  172 . The conformation of the soft outer coverings  164  and  172  with the optical fiber bundle  140  increases the contact area and the overall friction that provides the force for advancing and retracting the optical fiber bundle  140 . In alternative embodiments other fiber advancing mechanisms may be used. 
     An optional gasket  175  provides a seal between the face of the drive roller  160  and the cover  115 . Alternatively, a seal may be established between the drive roller axle portion  165   a  and the surface of the drive roller axle bore  180 . A keyway  162  in the driver roller bearing portion accepts a key  168  ( FIG. 1E ) that transmits torque applied to the knob  120 . 
     The receiver  110  includes a drive roller axle bearing cavity  166   a  and a pinch roller axle bearing cavity  176   a . The drive roller axle bearing cavity  166   a  and a pinch roller axle bearing cavity  176   a  are blind cavities; however, through holes may be used in other embodiments. 
     An optional storage cavity  155  provides a volume adjacent to drive roller  160  and pinch roller  170 . Upon retraction, the optical fiber bundle  140  will not easily resume its initial configuration and the storage cavity provides a local storage site. Although retraction may not be required to complete a particular medical procedure, it may be desirable to retract the optical fiber  140  for easier handling. 
       FIG. 1E  shows a back perspective exploded view of the optical probe adapter of  FIG. 1A . The cover  115  has an optional storage cavity  155  similar to that associated with the receiver  110 . The cover  115  includes a drive roller axle bearing cavity  166   b  and a pinch roller axle bearing cavity  176   b.    
     An axle  174  supports pinch roller  170 . Since it is desirable to minimize resistance to rotation, it is preferable that axle  174  not be fixed to pinch roller  170 . In contrast, drive roller axle portions  165   a  and  165   b  are integrated with drive roller  160 . A minimum resistance to rotation is desirable in the drive roller  160  so that it can hold the optical fiber  140  in a fixed position after alignment. 
     A key  168  transmits the torque applied to knob  120  to the pinch roller  160 . The knob  120 , key  168 , and drive roller  160  may be fabricated as an integrated unit or as components that are separable in whole or in part. A removable knob  120  and key  168  are desirable when they would interfere with positioning of an attached probe after extension of the optical fiber bundle  140 . 
       FIG. 2A  shows a perspective view  200  of an embodiment of an optical probe adapter  205  with an attached hypodermic needle  210 . In alternative embodiments a cylindrical cross-section may be substituted for the rectangular cross-section. Although the rectangular cross-section minimizes the size of the optical probe adapter, the radial symmetry of a cylindrical cross-section may provide greater ease of handling. 
     Although the hypodermic needle  210  is shown as shorter than the optical probe adapter  205 , the hypodermic needle  210  may be longer than the optical probe adapter  205 . For example, the optical probe adapter may have a length of about 10 centimeters and the hypodermic needle may have a length of 10 to 15 centimeters.  FIG. 2B  shows an alignment of an optical fiber  240  at the tip of the attached hypodermic needle  210  of  FIG. 2A . 
       FIG. 3  shows a diagram  300  of an embodiment of a probe positioning system. An optical coherence tomography (OCT) instrument  305   a  provides illumination and receives a reflected light signal through an optic fiber  310  that has a connector  315 . The optical coherence tomography (OCT) instrument  305   a  may be a battery powered portable instrument. The connector  315  mates to the optical fiber adapter  320  via the fiber optic coupler  320   a . The housing  320   b  contains a length of optical fiber that may be advanced to align with the distal tip  330  of a probe  325 . 
       FIG. 4  shows a flow chart diagram  400  for an embodiment of a method for inserting a probe using a system similar to that shown in  FIG. 3 . At step  405  an optical coherence tomography (OCT) instrument is attached to an optical fiber probe adapter. This connection will typically be made using a cable. A probe is also attached to the optical fiber probe adapter. The probe may be connected by a simple press fit or it may be connected by a mechanical interlock such as a thread, bayonet, or twist lock. 
     At step  410  the optical fiber is advanced from the optical fiber probe adapter and aligned within the probe. Generally, the optical fiber will be advanced to the vicinity of the distal tip of the probe. However, if a portion of the probe is transparent, the optical fiber may reside entirely within the probe. 
     At step  415  the probe is inserted to the desired location using the visual image provided by the OCT instrument. Probes for procedures such as catheterization and nerve blocks may be inserted with the optical fiber probe adapter. 
     At step  420  the probe is disconnected from the optical fiber probe adapter. The probe may be disconnected without changing the alignment of the optical fiber within the probe, or the optical fiber may be realigned prior to being disconnected. 
     At step  425  the optical fiber is withdrawn from the probe. At step  430  the optical fiber is retracted into the probe. Retraction of the optical fiber into the probe is an optional step and may be performed prior to withdrawal of the optical fiber from the probe. At step  435  a therapeutic device such as a syringe or a catheter is coupled to the probe. 
     While the invention has been described in detail with reference to preferred embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention.