Abstract:
A system and method for using a variable direction of view endoscope in conjunction with an electromechanical endoscope holder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. provisional application Ser. No. 60/554,973 filed on Mar. 20, 2004, entitled “Method and system for using a variable direction of view endoscope with a robotic endoscope holder”, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to electromechanical positioning of variable direction of view endoscopes.  
       BACKGROUND OF THE INVENTION  
       [0003]     Computer-controlled electromechanical positioning systems for endoscopes are disclosed in U.S. Pat. No. 5,515,478 to Wang and U.S. Pat. No. 5,524,180 to Wang et al. These multi degree-of-freedom devices provide the operator with the ability to accurately control the endoscopic viewing direction through electronic switches or voice commands and have become an important part of robotic minimally invasive surgical procedures. The shortcoming of such endoscopic positioning systems is that they can only provide a limited endoscopic viewing range because the mechanical mobility is outside rather than inside the inspection site and because these positioning systems are designed for use with fixed-angle endoscopes which do not have a variable line of sight. This is especially true in neuroendoscopy, sinoscopy, or otoscopy, where the endoscope shaft is physically constrained or must remain largely stationary to avoid injuring the patient.  
         [0004]     Variable direction of view endoscopes, as exemplified in U.S. Pat. No. 3,856,000 to Chikama, U.S. Pat. No. 6,371,909 to Hoeg, U.S. Pat. No. 6,560,013 to Ramsbottom, U.S. Pat. No. 4,697,577 to Forkner, U.S. Pat. No. 6,500,115 to Krattiger et al., U.S. Pat. No. 5,762,603 to Thompson, U.S. Pat. No. 5,313,306 to Kuban, U.S. Pat. No. 5,800,341 to McKenna et al., U.S. Pat. No. 6,364,830 to Durell, U.S. Pat. No. 3,572,325 to Bazell et al., U.S. Pat. No. 3,880,148 to Kanehira, U.S. Pat. No. 5,257,618 to Kondo, and by LTF TYPE V3 Laparo-Thoraco Videoendoscope from Olympus Optical Co., can vary their line of sight at the tip of the instrument, thus transferring the viewing mobility to the tip and relieving the problem of limited viewing range. Hale et al. discloses a computer-controlled variable direction of view endoscope, affording the operator accurate viewing navigation and positioning capabilities even from a fixed view point.  
         [0005]     A heretofore unanticipated combination of a computer-controlled endoscope positioning system and a computer-controlled variable direction of view endoscope affords new and powerful navigation capabilities. For example, coupling the 7DOF robotic endoscope holder disclosed in U.S. Pat. No. 5,524,180 to Wang with the 3DOF computer-controlled endoscope of U.S. Pat. No. 6,663,559 to Hale et al., yields a new 7DOF system with significant dexterity and wide ranging navigation capabilities. Many moves previously possible only in virtual endoscopy, which uses a virtual camera to “fly” through 3D volumetric models constructed from data obtained with a noninvasive imaging technique (MRI, CT, PET, ultrasound) are thus possible with a real camera having real-time optical imaging. Specifically, such a combined system would enable i) accurate scanning behind surfaces, ii) precise lesion or tumor inspection from nearly all angles, iii) precise post-operative diagnoses, iv) more versatility in approaching surgical targets, v) locking to a specific view and keeping it steady while the mechanism changes configuration, vi) stereoscopic reconstructions, and vii) better stereotactic navigation.  
         [0006]     Accordingly, the primary object of the present invention is to provide a system which merges/combines the advantages of robotic endoscope holders with the advantages of a variable direction of view endoscope and provides additional advantages. Still further objects and advantages will become apparent from the ensuing description and drawings.  
       BRIEF SUMMARY OF THE INVENTION  
       [0007]     In accordance with the present invention, a variable direction of view endoscope is coupled to robotic endoscope holder. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIGS. 1A and 1B  show variable direction of view endoscopes coupled to a robotic endoscope holder according to the preferred embodiment of the present invention.  
         [0009]      FIG. 2  illustrates the concept of scanning the lateral surface of an organ according to the preferred embodiment of the present invention.  
         [0010]      FIG. 3  shows the principle of visually locking on an object while changing the position of the endoscope to accommodate surgical tools or obtain stereoscopic data.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]     The following detailed description illustrates the invention by way of example, not by way of limitation of the principles of the invention. This description will enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what we presently believe is the best mode of carrying out the invention.  
       Preferred Embodiment  
       [0012]     Referring now to the drawings, in which like reference numbers represent similar or identical structures throughout,  FIG. 1  is a diagram of a basic variable direction of view endoscope  10  held by a robotic arm  12  with a base  14  and a base frame  15 . The robotic arm  12  has three actuated revolute joints  16 ,  18 ,  20  with rotational degrees of freedom  22 ,  24 ,  26 . The joints  16 ,  18 ,  20  are connected by links  28 ,  30 . A third link  32  extends from the joint  20  to an end-effector  34  which has a prismatic joint (not explicitly shown) and an associated tool frame  36 . The dynamic spatial relationship between the tool frame  36  and the base frame  15  is determined by the geometry of the joints  16 ,  18 ,  20  and links  28 ,  30 ,  32  and is in robotics called the forward kinematic transformation (or conversely the inverse kinematic transformation). Aside from the ability to slide and rotate the endoscope  10  along a linear degree of freedom  38  and a rotational degree of freedom  39 , the end-effector  34  passively holds the scope  10  and senses the dynamic attitude of an endoscope frame  40  fixed to the endoscope  10 . A mapping between the endoscope frame  40  and the tool frame  36  is given in U.S. Pat. No. 5,515,478 and U.S. Pat. No. 5,524,180 to Wang et al. and incorporates two additional degrees of freedom  41 ,  42  which allow the endoscope  10  to passively tilt relative to the end-effector  34 . The endoscope  10  itself has a view vector  43  and an associated view field  44  with at least two degrees of freedom  46 ,  48 . The 1 st  degree of freedom  46  permits rotation of the view vector  43  about the endoscope longitudinal axis  50 , which allows the view vector  43  to scan in a latitudinal direction  52 . This degree of freedom  46  is a duplicate of the rotational degree of freedom  39 ; only one of these is necessary for the full-fledged operation of the present invention. The 2 nd  degree of freedom  48  permits rotation of the view vector  43  about an axis  54  perpendicular to the longitudinal axis  50 , which allows the view vector  43  to scan in a longitudinal direction  56 . A 3 rd  degree of freedom  58  may also be available because it is usually possible to adjust the rotational orientation of the endoscopic image. A view frame  60  is associated with the view field  44 . The mapping between the view frame  60  and the endoscope frame  40  is described in U.S. Pat. No. 6,663,559 to Hale et al. who also describe the use of an environment frame or an arbitrary user-defined frame  62  dictating the motion of the view vector  43 . An overall kinematic relationship between the view frame  60  (or the arbitrary frame  62 ) and the base frame  15  can thus be calculated, providing the operator with 10 (one redundant) overall degrees of freedom for controlling the position, direction, and orientation of the endoscopic view point. This integrated system is thus a physical version of a virtual endoscopy method allowing the user to fly through an endoscopic space.  
         [0013]      FIG. 2  illustrates the concept of moving the tip of the endoscope  10  through a trajectory  64  associated with inspecting the far side of an organ  66 . The view vector  43  scans the surface as the endoscope  10  moves through the endoscopic space. Certain previous configurations  68 ,  70  of the integrated arm-endoscope system are shown. The endoscopic entry point  72  into the patient (not shown) acts as a fulcrum which applies lateral forces as the robotic arm  12  is actuated. Because the endoscope  10  is passively supported by the end-effector  34 , these lateral forces cause the endoscope  10  to tilt without the risk of injuring the patient. Note that the robotic arm  12  shown in this case has universal joints rather than revolute, yielding two additional degrees of freedom  74 ,  76  for each joint for a system total of 16. Depending on the application any type of joint or link can be used.  
         [0014]      FIG. 3  shows how the system of the present invention can be used to keep the view vector  43  trained on a target  74  while the system configuration changes. This technique is useful because it can provide topographic information which is difficult to obtain with a single 2D endoscopic view. Further, being able to view the same object from many different angles makes it possible to obtain stereoscopic still images of the object and perform general 3D endoscopic photography.  
         [0015]     Accordingly, the present invention provides an integrated system for robotically controlling a variable direction of view endoscope, merging the advantages of electromechanical endoscope positioning and variable direction of view endoscopy and affording new capabilities such as 3D endoscopic photography.  
         [0016]     The present invention has been described above in terms of a presently preferred embodiment so that an understanding of the present invention can be conveyed. However, there are many alternative modes of operation not specifically described herein but with which the present invention is applicable. For example, although specific manipulators where described, any mechanism known from the field of robotics would fall under the scope of this invention. Also, many different types of variable direction of view endoscopes such as rigid scopes with deflectable tips, flexible scopes, or semiflexible scopes, can be used. Different mathematical parameterizations would be required in order to accommodate the specific kinematics associated with various scopes, but the governing principle as described in this invention would remain the same. In addition, while the examples were given with respect to endoscopes for use in surgical procedures, the present invention would be equally applicable with respect to borescopes or the like for use in non-medical situations. The scope of the present invention should therefore not be limited by the embodiments illustrated, but rather it should be understood that the present invention has wide applicability with respect to robotic control of variable direction endoscopic viewing instruments. All modifications, variations, or equivalent elements and implementations that are within the scope of the appended claims should therefore be considered within the scope of the invention.