GRAPHICAL USER INTERFACE FOR USE IN A SURGICAL NAVIGATION SYSTEM WITH A ROBOT ARM

Abstract

A surgical navigation system includes: a tracker (125) for real-time tracking of a position and orientation of a robot arm (191); a source of a patient anatomical data (163) and a robot arm virtual image (166); a surgical navigation image generator (131) generating a surgical navigation image (142A) including the patient anatomy (163) and the robot arm virtual image (166) in accordance to the current position and/or orientation data provided by the tracker (125); a 3D display system (140) showing the surgical navigation image (142A).

Claims

1.-12. (canceled)

13. An apparatus, comprising: a memory; a processor operatively coupled to the memory, the processor configured to: determine, based on data associated with an operative plan of a surgical procedure, a suggested position and orientation of a robot arm configured to manipulate a surgical instrument in a surgical procedure; determine, based on tracking data associated with the robot arm, an actual position and orientation of the robot arm; and generate a surgical navigation image including (1) a virtual object indicative of the suggested position and orientation of the robot arm, (2) a virtual representation of the robot arm, (3) a virtual representation of the surgical instrument, and (4) a virtual representation of a portion of a patient anatomy; and a three-dimensional (3D) display system configured to display the surgical navigation image on a surface positionable between a head of an operator and a real-world environment including the patient anatomy such that the virtual representation of the portion of the patient anatomy, the virtual representation of the robot arm, and the virtual representation of the surgical instrument are collocated with real objects in the real-world environment in a field of view of the operator.

14. The apparatus of claim 13, wherein the 3D display system includes a 3D display and a see-through screen, the see-through screen being positionable between the head of the operator and the real-world environment, the 3D display configured to project the surgical navigation image onto the see-through screen.

15. The apparatus of claim 13, further comprising a tracking system configured to track the actual position and orientation of the robot arm, the processer further being operatively coupled to the tracking system and being configured to receive the tracking data from the tracking system.

16. The apparatus of claim 13, further comprising a position system associated with the robot arm, the position system including a set of encoders located at each joint of the robot arm and configured to provide the tracking data indicative of an angle or position of each element of the robot arm.

17. The apparatus of claim 13, wherein the processor is further configured to adapt the surgical navigation image based on a position and orientation of the head of the operator.

18. The apparatus of claim 13, wherein the processor is further configured to adapt the virtual representation of the robot arm to show or hide different portions of the robot arm.

19. The apparatus of claim 13, wherein the processor is further configured to adapt the virtual representation of the robot arm by changing an opacity of the virtual representation of the robot arm.

20. The apparatus of claim 13, wherein the surgical navigation image further includes a set of images depicting different orthogonal or arbitrary planes of the portion of the patient anatomy.

21. The apparatus of claim 13, wherein the surgical navigation image further includes surgical guidance for placement of an implantable device using the surgical instrument within the patient anatomy.

22. An apparatus, comprising: a memory; a processor operatively coupled to the memory, the processor configured to: determine, based on tracking data associated with a robot arm configured to manipulate a surgical instrument in a surgical procedure, an actual position and orientation of the robot arm; generate a surgical navigation image including (1) a virtual representation of the robot arm, (2) a virtual representation of the surgical instrument, and (3) a virtual representation of a portion of a patient anatomy; and adapt the virtual representation of the robot arm by changing at least one of: an opacity of the virtual representation of the robot arm, or selectively hiding one or more portions of the virtual representation of the robot arm; and a three-dimensional (3D) display system configured to display the surgical navigation image on a surface positionable between a head of an operator and a real-world environment including the patient anatomy such that the virtual representation of the portion of the patient anatomy, the virtual representation of the robot arm, and the virtual representation of the surgical instrument are collocated with real objects in the real-world environment in a field of view of the operator.

23. The apparatus of claim 22, wherein the 3D display system includes a 3D display and a see-through screen, the see-through screen being positionable between the head of the operator and the real-world environment, the 3D display configured to project the surgical navigation image onto the see-through screen.

24. The apparatus of claim 22, further comprising a tracking system configured to track the actual position and orientation of the robot arm, the processer further being operatively coupled to the tracking system and being configured to receive the tracking data from the tracking system.

25. The apparatus of claim 22, further comprising a position system associated with the robot arm, the position system including a set of encoders located at each joint of the robot arm and configured to provide the tracking data indicative of an angle or position of each element of the robot arm.

26. The apparatus of claim 22, wherein the processor is further configured to adapt the surgical navigation image based on a position and orientation of the head of the operator.

27. The apparatus of claim 22, wherein the surgical navigation image further includes a set of images depicting different orthogonal or arbitrary planes of the portion of the patient anatomy.

28. The apparatus of claim 22, wherein the surgical navigation image further includes surgical guidance for placement of an implantable device using the surgical instrument within the patient anatomy.

29. A method, comprising: determining, based on data associated with an operative plan of a surgical procedure, a suggested position and orientation of a robot arm configured to manipulate a surgical instrument in a surgical procedure; receiving, from a tracking system, tracking data associated with the robot arm; determining, based on the tracking data associated with the robot arm, an actual position and orientation of the robot arm; and generating a surgical navigation image including (1) a virtual object indicative of the suggested position and orientation of the robot arm, (2) a virtual representation of the robot arm, (3) a virtual representation of the surgical instrument, and (4) a virtual representation of a portion of a patient anatomy; and displaying, using a three-dimensional (3D) display system, the surgical navigation image on a surface positionable between a head of an operator and a real-world environment including the patient anatomy such that the virtual representation of the portion of the patient anatomy, the virtual representation of the robot arm, and the virtual representation of the surgical instrument are collocated with real objects in the real-world environment in a field of view of the operator.

30. The method of claim 29, wherein displaying the surgical navigation image on the surface includes displaying the virtual object indicative of the suggested position and orientation of the robot arm and one or more virtual guidance cues that indicate whether the robot arm has been placed in the suggested position and orientation of the robot arm.

31. The method of claim 29, further comprising adapting the virtual representation of the robot arm by selectively hiding one or more portions of the virtual representation of the robot arm.

32. The method of claim 29, further comprising adapting the virtual representation of the robot arm by changing an opacity of the virtual representation of the robot arm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The surgical navigation system and method are presented herein by means of non-limiting example embodiments shown in a drawing, wherein:

[0029] FIG. 1A shows a layout of a surgical room employing the surgical navigation system in accordance with an embodiment of the invention;

[0030] FIG. 1B shows a layout of a surgical room employing the surgical navigation system in accordance with an embodiment of the invention;

[0031] FIG. 1C shows a layout of a surgical room employing the surgical navigation system in accordance with an embodiment of the invention;

[0032] FIG. 2A shows components of the surgical navigation system in accordance with an embodiment of the invention;

[0033] FIG. 2B shows components of the surgical navigation system in accordance with an embodiment of the invention;

[0034] FIG. 3A shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0035] FIG. 3B shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0036] FIG. 3C shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0037] FIG. 3D shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0038] FIG. 3E shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0039] FIG. 3F shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0040] FIG. 3G shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0041] FIG. 3H shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0042] FIG. 3I shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0043] FIG. 3J shows an example of an augmented reality display in accordance with an embodiment of the invention;

[0044] FIG. 4A shows an embodiment of a 3D display system for use in an embodiment of the invention.

[0045] FIG. 4B shows another embodiment of a 3D display system for use in an embodiment of the invention.

[0046] FIG. 4C shows another embodiment of a 3D display system for use in an embodiment of the invention.

[0047] FIG. 4D shows another embodiment of a 3D display system for use in an embodiment of the invention.

[0048] FIG. 4E shows another embodiment of a 3D display system for use in an embodiment of the invention.

[0049] FIG. 5A show eye tracking in accordance with an embodiment of the invention.

[0050] FIG. 5B show eye tracking in accordance with an embodiment of the invention.

[0051] FIG. 6 shows a 3D representation of the results of the semantic segmentation on one vertebrae for use in an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0052] The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention.

[0053] The system presented herein is comprises a 3D display system 140 to be implemented directly on real surgical applications in a surgical room as shown in FIGS. 1A-1C. The 3D display system 140 as shown in the example embodiment comprises a 3D display 142 for emitting a surgical navigation image 142A towards a see-through mirror 141 that is partially transparent and partially reflective, such that an augmented reality image 141A collocated with the patient anatomy in the surgical field 108 underneath the see-through mirror 141 is visible to a viewer looking from above the see-through mirror 141 towards the surgical field 108.

[0054] The surgical room typically comprises a floor 101 on which an operating table 104 is positioned. A patient 105 lies on the operating table 104 while being operated by a surgeon 106 with the use of various surgical instruments 107. The surgical navigation system as described in details below can have its components, in particular the 3D display system 140, mounted to a ceiling 102, or alternatively to the floor 101 or a side wall 103 of the operating room. Furthermore, the components, in particular the 3D display system 140, can be mounted to an adjustable and/or movable floor-supported structure (such as a tripod). Components other than the 3D display system 140, such as the surgical image generator 131, can be implemented in a dedicated computing device 109, such as a stand-alone PC computer, which may have its own input controllers and display(s) 110,

[0055] In general, the system is designed for use in such a configuration wherein the distance d1 between the surgeon's eyes and the see-through mirror 141, is shorter than the distance d2, between the see-through mirror 141 and the operative field at the patient anatomy 105 being operated.

[0056] In addition, the system comprises a robot arm 191 for handling some of the surgical tools. The robot arm 191 may have two closed loop control systems: its own position system and one used with the optical tracker as presented herein. Both systems of control may work together to ensure that the robot arm is on the right position. The robot arm's position system may comprise encoders placed at each joint to determine the angle or position of each element of the arm. The second system may comprise a robot arm marker array 126 attached to the robot arm to be tracked by the tracker 125, as described below. Any kind of surgical robotic system can be used, preferably one that follows standards of the U.S. Food & Drug Administration.

[0057] FIG. 2A shows a functional schematic presenting connections between the components of the surgical navigation system and FIG. 2B shows examples of physical embodiments of various components.

[0058] The surgical navigation system comprises a tracking system for tracking in real time the position and/or orientation of various entities to provide current position and/or orientation data. For example, the system may comprise a plurality of arranged fiducial markers, which are trackable by a fiducial marker tracker 125. Any known type of tracking system can be used. For example in case of a marker tracking system, 4-point marker arrays are tracked by a three-camera sensor to provide movement along six degrees of freedom. A head position marker array 121 can be attached to the surgeon's head for tracking of the position and orientation of the surgeon and the direction of gaze of the surgeon—for example, the head position marker array 121 can be integrated with the wearable 3D glasses 151 or can be attached to a strip worn over the surgeon's head.

[0059] A display marker array 122 can be attached to the see-through mirror 141 of the 3D display system 140 for tracking its position and orientation, as the see-through mirror 141 is movable and can be placed according to the current needs of the operative setup.

[0060] A patient anatomy marker array 123 can be attached at a particular position and orientation of the anatomy of the patient.

[0061] A surgical instrument marker array 124 can be attached to the instrument whose position and orientation shall be tracked.

[0062] A robot arm marker array 126 can be attached to at least one robot arm 191 to track its position.

[0063] Preferably, the markers in at least one of the marker arrays 121-124 are not coplanar, which helps to improve the accuracy of the tracking system.

[0064] Therefore, the tracking system comprises means for real-time tracking of the position and orientation of at least one of: a surgeon's head 106, a 3D display 142, a patient anatomy 105, and surgical instruments 107. Preferably, all of these elements are tracked by a fiducial marker tracker 125.

[0065] A surgical navigation image generator 131 is configured to generate an image to be viewed via the see-through mirror 141 of the 3D display system, It generates a surgical navigation image 142A comprising data of at least one of: the pre-operative plan 161 (which are generated and stored in a database before the operation), data of the intra-operative plan 162 (which can be generated live during the operation), data of the patient anatomy scan 163 (which can be generated before the operation or live during the operation) and virtual images 164 of surgical instruments used during the operation (which are stored as 3D models in a database), as well as virtual image 166 of the robot arm 191.

[0066] The surgical navigation image generator 131, as well as other components of the system, can be controlled by a user (i.e. a surgeon or support staff) by one or more user interfaces 132, such as foot-operable pedals (which are convenient to be operated by the surgeon), a keyboard, a mouse, a joystick, a button, a switch, an audio interface (such as a microphone), a gesture interface, a gaze detecting interface etc. The input interface(s) are for inputting instructions and/or commands.

[0067] All system components are controlled by one or more computers which are/is controlled by an operating system and one or more software applications. The computer may be equipped with a suitable memory which may store computer program or programs executed by the computer in order to execute steps of the methods utilized in the system. Computer programs are preferably stored on a non-transitory medium. An example of a non-transitory medium is a non-volatile memory, for example a flash memory while an example of a. volatile memory is RAM, The computer instructions are executed by a processor, These memories are exemplary recording media for storing computer programs comprising computer-executable instructions performing all the steps of the computer-implemented method according the technical concept presented herein. The computer(s) can he placed within the operating room or outside the operating room. Communication between the computer(s) and the components of the system may be performed by wire or wirelessly, according to known communication means.

[0068] The aim of the system in some embodiments is to generate, via the 3D display system 140, an augmented reality image such as shown in FIG. 3J, and also possibly 3A-31. When the surgeon looks via the 3D display system 140, the surgeon sees the augmented reality image 141A which comprises:

[0069] the real world image: the patient anatomy, surgeon's hands and the instrument currently in use (which may be partially inserted into the patient's body and hidden under the skin);

[0070] and a computer-generated surgical navigation image 142A comprising the patient anatomy 163 and a virtual image 166 of the robot arm.

[0071] As a result, the augmented reality image comprises a virtual image 166 of the robot arm collocated with the real physical anatomy of the patient, as shown in FIG. 3B. Furthermore, the augmented reality image may comprise a guidance image 166A that indicates, according to the preoperative plan data, the suggested position and orientation of the robot arm 191.

[0072] The virtual image 166 of the robot arm may be configurable such that it can be selectively displayed or hidden, in full or in part (for example, some parts of the robot arm can be hidden (such as the forearm) and some (such as the surgical tool holder) can be visible). Moreover, the opacity of the robot arm virtual image 166 can be selectively changed, such that it does not obstruct the patient anatomy.

[0073] The display of the patient anatomy 163 can be configurable, such that at least one section of the anatomy 163A-163F is displayed and at least one other section of the anatomy 163A-163F is not displayed, as shown in FIGS. 3F-31.

[0074] Furthermore, the surgical navigation image may further comprise a 3D image 171 representing at least one of: the virtual image of the instrument 164 or surgical guidance indicating suggested (ideal) trajectory and placement of surgical instruments 107, according to the pre-operative plans 161. (as shown in FIG. 3C); preferably, three different orthogonal planes of the patient anatomical data 163: coronal 174, sagittal 173, axial 172; preferably, a menu 175 for controlling the system operation.

[0075] If the 3D display 142 is stereoscopic, the surgeon shall use a pair of 3D glasses 151 to view the augmented reality image 141A. However, if the 3D display 142 is autostereoscopic, it may be not necessary for the surgeon to use the 3D glasses 151 to view the augmented reality image 141A.

[0076] The virtual image of the patient anatomy 163 is generated based on data representing a three-dimensional segmented model comprising at least two sections representing parts of the anatomy. The anatomy can be for example a bone structure, such as a spine, skull, pelvis, long bones, shoulder joint, hip joint, knee joint etc. This description presents examples related particularly to a spine, but a skilled person will realize how to adapt the embodiments to be applicable to the other bony structures or other anatomy parts as well.

[0077] For example, the model can represent a spine, as shown in FIG. 6, with the following section: spinous process 163A, lamina 163B, articular process 163C, transverse process 163D, pedicles 163E, vertebral body 163F.

[0078] The model can be generated based on a pre-operative scan of the patient and then segmented manually by a user or automatically by a computer, using dedicated algorithms and/or neural networks, or in a hybrid approach including a computer-assisted manual segmentation.

[0079] For example, a convolutional neural network can be employed.

[0080] Preferably, the images of the orthogonal planes 172, 173, 174 are displayed in an area next (preferably, above) to the area of the 3D image 171, as shown in FIG. 3A, wherein the 3D image 171 occupies more than 50% of the area of the see-through device 141.

[0081] The location of the images of the orthogonal planes 172, 173, 174 may be adjusted in real time depending on the location of the 3D image 171, when the surgeon changes the position of the head during operation, such as not to interfere with the 3D image 171.

[0082] Therefore, in general, the anatomical information of the user is shown in two different layouts that merge for an augmented and mixed reality feature. The first layout is the anatomical information that is projected in 3D in the surgical field. The second layout is in the orthogonal planes.

[0083] The surgical navigation image 142A is generated by the image generator 131 in accordance with the tracking data provided by the fiducial marker tracker 125, in order to superimpose the anatomy images and the instrument images exactly over the real objects, in accordance with the position and orientation of the surgeon's head. The markers are tracked in real time and the image is generated in real time. Therefore, the surgical navigation image generator 131 provides graphics rendering of the virtual objects (patient anatomy, surgical plan and instruments) collocated to the real objects according to the perspective of the surgeon's perspective.

[0084] For example, surgical guidance may relate to suggestions (virtual guidance clues 164) for placement of a pedicle screw in spine surgery or the ideal orientation of an acetabular component in hip arthroplasty surgery. These suggestions may take a form of animations that show the surgeon whether the placement is correct. The suggestions may be displayed both on the 3D holographic display and the orthogonal planes. The surgeon may use the system to plan these orientations before or during the surgical procedure.

[0085] In particular, the 3D image 171 is adapted in real time to the position and orientation of the surgeon's head. The display of the different orthogonal planes 172, 173, 174 may be adapted according to the current position and orientation of the surgical instruments used.

[0086] The aligning the line of sight of the surgeon onto the see-through mirror with the patient anatomy underneath the see-through mirror, involving the scaling and orientation of the image, can be realized based on known solutions in the field of computer graphics processing, in particular for virtual reality, including virtual scene generation, using well-known mathematical formulas and algorithms related to viewer centered perspective. For example, such solutions are known from various tutorials and textbooks (such as The Future of the CAVE″ by T. A. DeFanti et al, Central European Journal of Engineering, 2010, DOI: 10.2478/s13531-010-0002-5).

[0087] FIG. 3B shows an example indicating collocation of the virtual image of the patient anatomy 163 and the real anatomy 105.

[0088] For example, as shown in FIG. 3C, the 3D image 171 may demonstrate a mismatch between a supposed/suggested position of the instrument according to the pre-operative plan 161, displayed as a first virtual image of the instrument 164A located at its supposed/suggested position, and an actual position of the instrument, visible either as the real instrument via the see-through display and/or a second virtual image of the instrument 164B overlaid on the current position of the instrument. Additionally, graphical guiding cues, such as arrows 165 indicating the direction of the supposed change of position, can be displayed.

[0089] FIG. 3D shows a situation wherein the tip of the supposed position of the instrument displayed as the first virtual image 164A according to the pre-operative plan 161 matches the tip of the real surgical instrument visible or displayed as the second virtual image 164B. However, the remainder of objects do not match, therefore the graphical cues 165 still indicate the need to change position. The surgical instrument is close to the correct position and the system may provide information on how close the surgical instrument is to the planned position.

[0090] FIG. 3E shows a situation wherein the supposed position of the real surgical instrument matches the position of the instrument according to the pre-operative plan 161, i.e. the correct position for surgery. In this situation the graphical cues 165 are no longer displayed, but the virtual images 164A, 164B may be changed to indicate the correct position, e.g. by highlighting it or blinking.

[0091] In some situations, the image of the full patient anatomy 163, as shown in FIG. 3A, may be obstructive. To solve this problem, the system allows a selective display of the parts of the anatomy 163, such that at least one part of the anatomy is shown and at least one other part of the anatomy is not shown.

[0092] For example, the surgeon may only want to see isolated parts of the spinal anatomy during spine surgery (only vertebral body or only the pedicle). Each part of the spinal anatomy is displayed at the request of the surgeon. For example the surgeon may only want to see the virtual representation of the pedicle during placement of bony anchors. This would be advantageous, as it would not have any visual interference from the surrounding anatomical structures.

[0093] Therefore, a single part of the anatomy may be displayed, for example only the vertebral body 163F (FIG. 3F) or only the pedicles 163E (FIG. 3G). Alternatively, two parts of the anatomy may be displayed, for example the vertebral body 163F and the pedicles 163E (FIG. 3H); or a larger group of anatomy parts may be displayed, such as the top parts of 163A-D of the spine (FIG. 3I).

[0094] The user may select the parts that are to be displayed via the input interface 132.

[0095] For example, the GUI may comprise a set of predefined display templates, each template defining a particular part of the anatomy to be displayed (such as FIG. 3F, 3G) or a plurality of parts of the anatomy to be displayed (such as FIG. 3H, 3I). The user may then use a dedicated touch-screen button, keyboard key, pedal or other user interface navigation element to select a particular template to be displayed or to switch between consecutive templates.

[0096] Alternatively, the GUI may display a list of available parts of anatomy to be displayed and the user may select the parts to be displayed.

[0097] The GUI interface for configuring the parts that are to be displayed can be configured to be operated directly by the surgeon or by an assistant person.

[0098] The foregoing description will provide examples of a 3D display 142 with a see-through mirror 141, which is particularly effective to provide the surgical navigation data. However, other 3D display systems can be used as well to show the automatically segmented parts of anatomy, such as 3D head-mounted displays.

[0099] The see-through mirror (also called a half-silvered mirror) 141 is at least partially transparent and partially reflective, such that the viewer can see the real world behind the mirror but the mirror also reflects the surgical navigation image generated by the display apparatus located above it.

[0100] For example, a see-through mirror as commonly used in teleprompters can be used. For example, the see-through mirror 141 can have a reflective and transparent rate of 50R/50T, but other rates can be used as well.

[0101] The surgical navigation image is emitted from above the see-through mirror 141 by the 3D display 142.

[0102] In an example embodiment as shown in FIGS. 4A and 4B, a special design of the 3D display 142 is provided that is compact in size to facilitate its mounting within a limited space at the operating room. That design allows generating images of relatively large size, taking into account the small distance between the 3D display 142 and the see-through mirror 141, without the need to use wide-angle lens that could distort the image.

[0103] The 3D display 142 comprises a 3D projector 143, such as a DLP projector, that is configured to generate an image, as shown in FIG. 4B (by the dashed lines showing image projection and solid lines showing images generated on particular reflective planes). The image from the 3D projector 143 is firstly refracted by an opaque top mirror 144, then it is refracted by an opaque vertical mirror 145 and subsequently placed on the correct dimensions on a projection screen 146 (which can be simply a glass panel). The projection screen 146 works as a rear-projection screen or a small bright 3D display. The image displayed at the projection screen 146 is reflected by the see-through mirror 141 which works as an augmented reality device. Such configuration of the mirrors 144, 145 allows the image generated by the 3D projector 143 to be shown with an appropriate size at the projection screen 146. The fact that the projection screen 146 emits an enlarged image generated by the 3D projector 143 makes the emitted surgical navigation image bright, and therefore well visible when reflected at the see-through mirror 141. Reference 141A indicates the augmented reality image as perceived by the surgeon when looking at the see-through mirror 141.

[0104] The see-through mirror 141 is held at a predefined position with respect to the 3D projector 143, in particular with respect to the 3D projector 143, by an arm 147, which may have a first portion 147A fixed to the casing of the 3D display 142 and a second portion 147B detachably fixed to the first portion 147A. The first portion 147A may have a protective sleeve overlaid on it. The second portion 147B, together with the see-through mirror 141, may be disposable in order to maintain the sterility of the operating room, as it is relatively close to the operating field and may be contaminated during the operation. The arm can also be foldable upwards to leave free space of the work space when the arm and augmented reality are not needed.

[0105] In alternative embodiments, as shown for example in FIGS. 4C, 4D, 4E, alternative devices may be used in the 3D display system 140 in place of the see-through mirror 141 and the 3D display 142.

[0106] As shown in FIG. 4C, a 3D monitor 146A can be used directly in place of the projection screen 146.

[0107] As shown in FIG. 4D, a 3D projector 143 can be used instead of the 3D display 142 of FIG. 4A, to project the surgical navigation image onto a see-through projection screen 141B, which is partially transparent and partially reflective, for showing the surgical navigation image 142A and allowing the surgical field 108 to be seen. A lens 141C can be used to provide appropriate focal position of the surgical navigation image.

[0108] As shown in FIG. 4F, the surgical navigation image can be displayed at a three-dimensional see-through display 141D and viewed by the user via a lens 141C used to provide appropriate focal position of the surgical navigation image.

[0109] Therefore, each of the see-through projection screen 141B, the see-through display 141D and the see-through mirror 141 can be commonly called a see-through device.

[0110] If a need arises to adapt the position of the augmented reality screen with respect to the surgeon's head (for example, to accommodate the position depending on the height of the particular surgeon), the position of the whole 3D display system 140 can be changed, for example by manipulating an adjustable holder (a surgical boom) 149 on FIG. 1A, by which the 3D display 142 is attachable to an operating room structure, such as a ceiling, a wall or a floor.

[0111] An eye tracker 148 module can be installed at the casing of the 3D display 142 or at the see-through device 141 or at the wearable glasses 151, to track the position and orientation of the eyes of the surgeon and input that as commands via the gaze input interface to control the display parameters at the surgical navigation image generator 131, for example to activate different functions based on the location that is being looked at, as shown in FIGS. 5A and 5B.

[0112] For example, the eye tracker 148 may use infrared light to illuminate the eyes of the user without affecting the visibility of the user, wherein the reflection and refraction of the patterns on the eyes are utilized to determine the gaze vector (i.e. the direction at which the eye is pointing out). The gaze vector along with the position and orientation of the user's head is used to interact with the graphical user interface. However, other eye tracking algorithms techniques can be used as well.

[0113] It is particularly useful to use the eye tracker 148 along with the pedals 132 as the input interface, wherein the surgeon may navigate the system by moving a cursor by eyesight and inputting commands (such as select or cancel) by pedals.

[0114] While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. Therefore, the claimed invention as recited in the claims that follow is not limited to the embodiments described herein.