Abstract:
A method of displaying a point of interest on an object, comprising preparing a reference pattern of the object, which reference pattern includes the point of interest in a visually-discernible manner on the object and further includes three visually-discernible reference points on the object, superposing the reference pattern on the object, effecting relative movement between the reference pattern and the object to optically align the three reference points on the reference pattern with three corresponding reference points on the subject and displaying the reference pattern superposed on the object such that the point of interest on the reference pattern is visually indicated on the object.

Description:
FIELD AND BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to display methods and apparatus particularly useful for displaying working operations to be performed on objects.  
           [0002]    The invention in especially useful for displaying the location, direction, and/or magnitude a surgical operation is to be performed on a patient, such as drilling a hole in a patient&#39;s bone for purposes of implant surgery, and in therefore described below with respect to such an application. It will be appreciated, however, that the invention could also be used in many other surgical operations, as well as in many industrial or manufacturing operations, as described below.  
           [0003]    The success of a surgical implant into a subject&#39;s bone depends to a high degree on the precision exercised in the location, direction, and/or depth of drilling an initial hole through the subject&#39;s bone for the implant, and thereby on the skill and experience of the person performing the drilling. This is particularly true in dental implants but also applies with respect to many other surgical procedures, as well as many industrial and manufacturing procedures requiring various operations to be precisely performed.  
         OBJECTS AND BRIEF SUMMARY OF THE INVENTION  
         [0004]    An object of the present invention is to provide novel display methods and apparatus having advantages, as will be described more particularly below.  
           [0005]    A particular object of the present invention is to provide novel methods and display apparatus especially useful for assisting in the performance of various surgical, as well as non-surgical, procedures by providing an optical guide which displays the location, direction, and/or magnitude that a critical operation is to be performed. While the invention is particularly useful with respect to making dental implants, it can also be used in many other procedures, such as industrial and/or manufacturing processes requiring a critical working operation to be performed at a precise location, in a precise direction, and/or to a precise magnitude (e.g., depth of drilling a hole).  
           [0006]    According to a broad aspect of the present invention, there is provided a method of displaying a point of interest on an object, comprising: preparing a reference pattern of the object, which reference pattern includes the point of interest in a visually-discernible manner on the object and further includes three visually-discernible reference points on the object; superposing the reference pattern on the object; effecting relative movement between the reference pattern and the object to optically align the three reference points on the reference pattern with three corresponding reference points on the object; and displaying the reference pattern superposed on the object such that the point of interest on the reference pattern is visually indicated on the object.  
           [0007]    As will be described more particularly below, the invention is particularly useful wherein the object is a physical object, and the point of interest indicates the location, direction and/or magnitude a working operation is to be performed on the physical object.  
           [0008]    According to one described preferred embodiment, the reference pattern is prepared in the form of a physical member having the configuration of the physical object. In this embodiment, the reference pattern is manipulated by manipulating the physical member.  
           [0009]    A second embodiment is described wherein the reference pattern is prepared in the form of a computer-generated image having the configuration of the physical object. In this embodiment, the reference pattern is manipulated by electronically manipulating the computer-generated image.  
           [0010]    A further embodiment is described below wherein the object is an image of the physical object, and the point of interest indicates the location of an element in the physical object.  
           [0011]    The method of the present invention may be applied to display the object, and reference pattern superposed thereon, at a single station where a specific operation is to be performed. An additional advantage of the present invention, however, is that the object and the reference pattern superposed thereon may be displayed simultaneously at a plurality of stations, e.g., for instructional purposes.  
           [0012]    As will be described below, the method of the present invention is particularly useful for performing surgical implant operations such as drilling a hole in a patient&#39;s jaw for purposes of implanting a dental device, or for performing other surgical operations, such as incision operations. However, the invention may also be used in non-surgical operations where a high degree of precision is required with respect to identifying the location of an element in the physical object, or in indicating the location, direction, and/or magnitude of a working operation, such as manufacturing or repairing precision parts, sculpturing, etc.  
           [0013]    The invention also provides apparatus for displaying a point of interest in an object, or the location, direction, and/or magnitude a working operation is to be performed, in accordance with the above-described method.  
           [0014]    Further features and advantages of the invention will be apparent from the description below.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:  
         [0016]    [0016]FIG. 1 diagrammatically illustrates a simplified apparatus constructed in accordance with the present invention to aid in the performance of a working operation requiring a high degree of precision, in this case, the drilling of one or more holes through a patient&#39;s jaw for purposes of implanting a dental device;  
         [0017]    [0017]FIG. 2 diagrammatically illustrates the apparatus of FIG. 1 wherein the reference pattern is computer-generated.  
         [0018]    [0018]FIG. 3 diagrammatically illustrates a more sophisticated apparatus constructed in accordance with the invention also using a computer-generated image for the reference pattern rather than a physical member, and displaying the reference pattern superposed on the object at one or more stations;  
         [0019]    [0019]FIG. 4 diagrammatically illustrates another apparatus constructed in accordance with the present invention to enable the viewer to selectively view the object from one side or the opposite side;  
         [0020]    [0020]FIG. 4 a  illustrates the apparatus of FIG. 4 when viewed from the opposite side;  
         [0021]    [0021]FIGS. 4 b  and  4   c  illustrate other arrangements that may be used with the apparatus of FIG. 4;  
         [0022]    [0022]FIG. 5 diagrammatically illustrates further features in a preferred embodiment of the invention for fixing the object with respect to the reference pattern and the displaying device;  
         [0023]    and FIG. 6 diagrammatically illustrates another apparatus constructed in accordance with the present invention in which the reference pattern is projected on an image of the object, rather than on the actual physical object. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0024]    With reference first to FIG. 1, there is diagrammatically shown a simplified version of an apparatus constructed in accordance with the present invention for performing a working operation on an object, generally designated  10 , requiring precision in the location, direction, and magnitude a working operation is to be performed on the object, In this case, the object  10  is the mouth of a subject, and the working operation to be performed is the drilling of one or more holes in the jaw of the subject each at a precise location, direction, and depth, for implanting a dental device.  
         [0025]    For performing this working operation, a reference pattern, generally designated  20 , is first constructed having a configuration corresponding to that of the object, i.e., the subject&#39;s jaw  10 . Reference pattern  20  includes three visually-discernible reference points  21 ,  22 ,  23 , and also one or more visually-discernible guides  24  indicating the location, direction, and depth each working (drilling of a hole) operation is to be performed on the object  10 . For example, the reference points  21 - 23  may be simple opaque dots, and the guides  24  may be pins inserted into holes drilled at locations, orientations, and depths according to each hole to be drilled in the subject&#39;s jaw for implanting the dental device. If the pins are of known length, the viewable end of the pin protruding from the hole will indicate the depth of the hole to be drilled.  
         [0026]    The reference pattern  20  is illuminated by a light source, schematically shown at  25 , and its image is reflected by a 45° mirror  30  towards a beam splitter  40 . Beam splitter  40  is used for projecting the virtual image  20 ′ of the reference pattern  20  onto the subject&#39;s jaw  10 , and also for viewing the subject&#39;s jaw with the reference pattern superposed thereon. Thus, beam splitter  40  includes a first face  41  facing the subject&#39;s jaw  10 , a second face  42  facing the 45° mirror  30  projecting the reference pattern, and a third face  43  for viewing the subject&#39;s jaw  10  with the image of the reference pattern  20 ′ superposed thereon. The illustrated apparatus further includes an eyepiece  44  aligned with the center of face  43  of the beam splitter  40  for viewing the subject&#39;s jaw  10  with the superposed reference pattern image  20 ′.  
         [0027]    The three reference points  21 - 23  in the reference pattern  20  are selected so that corresponding points  11 ,  12  and  13  in the patient&#39;s jaw  10  can be easily identified and discerned when viewing the patient&#39;s jaw through the beam splitter  40 . The subject&#39;s jaw is illuminated by a light source schematically indicated at  15 .  
         [0028]    After the reference pattern  20  has been optically projected onto the patient&#39;s jaw  10 , the reference pattern is then manipulated to optically align the three reference points  21 ′- 23 ′ of the projected image  20 ′ of the reference pattern with the three corresponding reference points  11 - 13  of the subject&#39;s jaw. Some adjustment may also be made of the mirror  30  and beam splitter  40 , if desired. Since three points in three-dimensional space define a plane, it will be appreciated that the alignment of the three reference points  21 ′- 23 ′ of the reference pattern image  20 ′ with the corresponding points  11 - 13  of the subject&#39;s jaw  10  will produce a three-dimensional alignment of the reference pattern with the subject&#39;s jaw. When the reference pattern is so aligned with the subject&#39;s jaw, the projected images  24 ′ of the guides  24  on the reference pattern will clearly indicate, at  14 , the location, direction, and/or magnitude each working operation (e.g., drilling of a hole for receiving a dental implant) is to be performed in the subject&#39;s jaw.  
         [0029]    A shutter system is used to faciliate the alignment of the reference pattern  20  with the subject&#39;s jaw  10 . For this purpose, a first shutter  45  in interposed between face  41  of beam splitter  40  and the subject&#39;s jaw  10 , and a second shutter  46  is interposed between face  42  and the 45° mirror  30  projecting the reference pattern  20 . The two shutters  45 ,  46  may be alternately opened and closed at a sufficiently high speed so that the viewer, while viewing the subject&#39;s jaw via face  43  of beam splitter  40  during the alignment phase, will easily see, by persistence of vision, the image  20 ′ of reference pattern  20  superposed on the subject&#39;s jaw  10 .  
         [0030]    The two shutters  45 ,  46 , may be mechanical shutters, such as rotating discs, driven by a control unit schematically shown at  47 . The two shutters  45 ,  46 , however, may also be liquid crystal shutters which are electronically controlled by the control unit  47 . Where the object, with the superposed reference pattern, is viewed by means of an electronic camera an will be described below, the focus control of the camera may be used for the shutters. The two shutters may be alternately opened and closed during the alignment phase and may be left open during the working phase.  
         [0031]    [0031]FIG. 2 illustrates another embodiment of the invention wherein the reference pattern, instead of being a physical pattern as shown at  20  in FIG. 1, is in the form of a computer generated image, generally designated  50 . The reference pattern may be generated from the particular patient by any of the known techniques, such as CT (computerized topography), MRI (magnetic resonance imaging), or three-dimensional photographic techniques. The image may be generated in real time with the performance of the working operation, or it may be generated and stored in digital form and later used in the performance of the working operation.  
         [0032]    The computer-generated image  50  also includes the three visually-discernible reference points  51 ,  52 ,  53 . It may also include, or it may have applied to it as an overlayer, the visually-discernible guide  54  indicating the location, direction, and/or magnitude the working operation is to be performed on the object, e.g., the drilling of one or more holes in the subject&#39;s jaw for purposes of receiving a dental implant.  
         [0033]    The reference pattern  50  in the apparatus of FIG. 2 is generated and manipulated by the computer  56  to align the three reference points  51 - 53  with the subject&#39;s jaw when superposed thereon, as described above with respect to FIG. 1. Since computer-generated images can be easily electronically manipulated, it is not necessary to include the 45° mirror  30  in the system of FIG. 1, which was provided to invert the image of the reference pattern so that it will be properly oriented with the subject&#39;s jaw when superposed thereon.  
         [0034]    [0034]FIG. 3 illustrates a further variation wherein the apparatus includes an electronic 3-D camera  57  connected to the computer  56  for generating the reference pattern from the patient&#39;s jaw  10 , and another electronic 3-D camera  60  which digitizes this information and displays it in one or more monitors  61   a -- 61   n.  An advantage of this arrangement is that the viewed image can be simultaneously displayed in a plurality of monitors located at a plurality of stations for instructing a plurality of students with respect to the particular operation to be performed. For example, an instructor could perform the one or more critical working operations on the object  10 , or a model of the object, to produce the reference pattern  50 , while the operations of the instructor so produced are superposed on the object  10 , or model thereof, assigned to each student located at a station equipped with a monitor  61   a - 61   n,  for guiding the students in the operations to be performed on their objects. The operations performed by an instructor could be recorded as course instructional material, or could be performed in a real time manner by the instructor with the performance by the students.  
         [0035]    [0035]FIGS. 4 and 4 a  illustrate a variation wherein the 45° mirror  30  in FIG. 1 is replaced by a second beam splitter  70 . An advantage of such an arrangement is that it provides great flexibility according to the particular situation. Thus, the user can view the object  10  from one side, via beam splitter  40  as shown in FIG. 4, or from the opposite side, by rotating the two beam splitters and the eyepiece 180°, as shown in FIG. 4 a.  FIG. 4 b  illustrates using another face of beam splitter  40  for viewing the object  10  with the superposed reference pattern  20 ′; and FIG. 4 c  illustrates using another face of beam splitter  20  for projecting the image of the reference pattern  20  on the object  10 .  
         [0036]    If the object to be worked on is a moving object, such as a body part of a patient (as distinguished from a non-moving object such as a industrial part to be manufactured or processed), it would be necessary to immobilize or secure the object with respect to the reference pattern and the viewing device during the alignment phase and also during the working phase. FIG. 5 schematically illustrates such an arrangement as applied to the two beam-splitter setup of FIGS. 4 and 4 a.  Thus, both beam splitters  40 ,  70  are carried by a common support  80  mounted in cantilever fashion from the side, as shown at  81  (or mounted from above, not shown). The subject&#39;s head is fixed with reference to the reference pattern  20  and the camera  44  by means of an anchoring member  82  which firmly engages the subject&#39;s head and is secured from the side (or from above) against all movement. Where the operation to be performed is a dental operation, such as drilling a hole in the subject&#39;s jaw for a dental implant, both jaws of the subject should be immobilized, which can be done by a chuck (not shown) inserted between the subject&#39;s jaws and firmly locking them in a fixed open position.  
         [0037]    [0037]FIG. 5 also illustrate a further variation if a 2-D cammera  44  is used, rather than a 3-D camera. Thus, as shown in FIG. 5, a mirror  83  may be used to produce an image of the 2-D reference pattern  20  in a different plans from that of the camera in order to obtain the perception of depth.  
         [0038]    As indicated earlier, whenever a camera is used for viewing the object with the superposed reference pattern, the manual focus control of the camera may be used for the shutters. Thus, focussing the image effectively “opens” the shutter, and defocussing the image effectively “closes” the shutter.  
         [0039]    The apparatus illustrated in FIG. 5 is otherwise constructed and operates in substantially the same manner as described above.  
         [0040]    [0040]FIG. 6 illustrates a still further arrangement, wherein the reference pattern is superposed, not on the physical object itself, but rather on an image of the physical object, and not by optical means, but rather by electronic means.  
         [0041]    Thus, as shown in FIG. 6, a reference pattern, schematically indicated at  80 , is generated in any known manner, e.g., by X-ray, CT or MIR. This reference pattern includes the three reference points  81 ,  82  and  83 , respectively, and also the point of interest shown at  85 . For example, the point of interest  85  may be a piece of shrapnel lodged in a patient&#39;s leg.  
         [0042]    The reference pattern  80  is fed to a computer  86 . Computer  86  also receives, via a camera  88 , an image  90  of the actual physical object  90 ′, in this case the patient&#39;s leg. The physical object  90 ′ also carries the three corresponding reference points, shown at  91 ,  92 ,  93 , respectively.  
         [0043]    Thus, the computer  86  produces a display, shown at  96 , of the reference image  80  and the image  90  of the actual physical object  90 ′. Either of these images may then be manipulated by the operator to superpose them and to align their corresponding reference points with each other, i.e.,  81  with  91 ,  82  with  92  and  83  with  93 . When the two images are thus superposed and aligned, it will be seen that the point of interest, namely element  85  in the reference pattern  80 , will be superposed on the image  90  of the actual physical object  90 ′, thereby enabling the observer to see exactly the location of that element (e.g., shrapnel) in the subject&#39;s leg to faciliate its removal.  
         [0044]    If the physical object  90 ′ being examined is not fixed in space, it is necessary to compensate, in the display of the reference pattern, for any movements in the physical object. This is done in the arrangement illustrated in FIG. 6 by providing an electrical gyro system, schematically indicated at  95 , to detect any movements of the physical object and to feed such movements into the computer  86 . The computer is thus able to make the appropriate changes in the spatial display of the reference pattern  80 . Thus, the gyro detector  95  in FIG. 6 serves basically the same function as the mechanical coupling in FIG. 5, to compensate the spatial positioning of the reference pattern for any movements of the actual physical object being examined.  
         [0045]    While the invention has been described with respect to several preferred embodiments, it will be appreciated that these are set forth merely for purposes of example. Thus, the invention could be used in other surgical operations, e.g., for other implantations, for precise incisioning, for precise suturing, etc. Also, the invention could be used in many non-surgical operations, e.g., manufacturing, repairing, and sculpturing operations. Many other variations, modifications and applications of the invention will be apparent.