Abstract:
A software-integrated disposable kit contains a series of sterile packages which hold instrumented surgical tools, surgical accessories, user input computer controlling peripherals (e.g. mouse, keyboard), markers, and a one time use digital medium. When image guided surgery is to be performed, the digital medium is inserted into the computer and the user interface is displayed. The digital medium stores a portion of the software which, in combination with software on the computer, provides all of the software necessary for full user functionality (e.g. display diagnostic image information, tracking surgical instruments, superimposition of surgical tools). At the end of a surgical procedure, the digital medium is deactivated or encrypted and the used surgical tools are then disposed of without reuse. The system allows the user to save relevant information obtained from the surgery (e.g. images, notes) on the digital medium which is encrypted against reuse and archived.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the art of image guided surgery. It finds particular application in conjunction with neurosurgical and orthopedic procedures and will be described with particular reference thereto. However, it is to be appreciated that the present invention is equally applicable to a wide range of image guided surgical applications in humans as well as veterinary applications. 
     Heretofore, images of a region of a patient in which surgery is planned have been made using magnetic resonance imaging systems, computed tomography, or other similar imaging modalities. These techniques generate a substantial amount of data, which is then manipulated through software to provide three-dimensional guidance within the imaged region. Typically, to facilitate diagnoses and treatment through image guidance, this data is manipulated using a computer supplemented with other specialized computer hardware to display selected views during surgery, e.g., orthogonal views, slices, perspective renderings, or the like. 
     Acquired images used for image guided surgery typically use anatomical reference markers which are commonly imaged with the patient. At the surgical site, acoustic, infrared, video camera, or other tracking technologies are utilized to determine the location of the markers relative to the patient and the surgical site. Additional computer software is provided to register the coordinate system of the markers, hence the patient, with the image(s). Thereafter, the same system is used to monitor the current position of surgical tools instrumented with similar markers, and coordinate their position in physical space with their position in the image(s). In this manner, the current position of the tool or probe relative to obscured portions of the patient&#39;s anatomy is readily determined. This facilitates implementing minimally invasive techniques by allowing the surgeon to use the acquired image(s) to see below the visible surface of the patient. For example, the surgeon can use the software&#39;s graphic user interface to mark the entry point and proposed trajectory of a pedicle screw on a patient&#39;s spine. The marked image(s) can then be used to enable the surgeon to follow the trajectory created below the surface with the instrumented surgical tool to be sure that the screw will not impinge the spinal cord and that it will engage sufficient bone to anchor properly, and the like. 
     In prior image guided surgery systems, different tools have been used for different portions of the human anatomy. To accommodate the use of different tools, the surgeon typically needs to calibrate the tool to the system. That is, the system needs to know the length, diameter, distances between various portions of the tool and the markers mounted on the tool, relative locations of markers and a tool axis, and the like. Prior image guided surgery systems did not allow use of non-instrumented or standard surgical tools. Also, in prior image guided surgery systems, as new tools are developed or as tools are modified, information about the tools loaded into the system must be reloaded on the entire installed base. Similar reinstallation problems occur when improvements are made to the software. 
     Prior image guided surgery systems also relied on reusable surgical tools. This has several drawbacks. First, with use, tools with cutting edges become dull. Second, since the tools are sterilized between uses, infection to the patient is possible due to a potential failure of the sterilization procedure. 
     Typically, image guided surgery systems are universal, i.e., applicable to any portion of the human anatomy that can be clearly imaged with reference markers. Computer software is provided to handle the imaging and alignment needs in virtually any region of the human anatomy. In some instances, the image guided surgery software is incorporated directly into the diagnostic imaging device. In other instances, additional expensive hardware is provided separately. 
     Prior image guided surgery systems have also relied on a capital equipment sales model, which has resulted in limited market acceptance. Prior image guided surgery systems have been large in size and cost-prohibitive for most. The shipping logistics has been expensive and cumbersome. 
     The present invention contemplates a new and improved method for image guided surgery, which overcomes the above-referenced problems and several others. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, a method of image guided surgery is provided which includes use of a (1) low cost integrated computer, (2) software-integrated disposable kits, (3) sterile disposable surgical tools and accessories, and a (4) tracking system used to locate the instrumented surgical tools during surgery. 
     In accordance with another aspect of the present invention, a low cost integrated computer is provided. The computer contains a portion of image guided surgery software to provide minimal user functionality e.g., retrieval of previously saved surgical information, preoperative surgical planning, etc. Image guided surgery using this method is not possible with the computer alone. Full user functionality is enabled only when the proper digital medium obtained from a software-integrated disposable kit, as described below, is inserted into a drive on the computer. Standard peripherals e.g., keyboard, mouse, are also included with kit. A display is also provided but is not part of the kit. Wireless peripherals can also be included as part of the kit to enable remote access to the software&#39;s graphic user interface. The computer can be included as part of a low cost mobile cart as well. 
     In accordance with another aspect of the present invention, a software-integrated disposable kit is also provided which includes (1) sterile instrumented disposable surgical tools and (2) a disposable one-time use digital medium, which contains the remaining a portion of the image guided surgery software to enable full user functionality. The digital medium will contain at least (i) a one-time use application specific software module and (ii) descriptive information concerning the surgical tools and other accessories. Further, other accessories, such as cables used to connect the computer to an imaging device e.g., fluoroscope, in sterile condition in sterile packaging which are used in the identified surgical procedure are present in the kit. Other accessories, including but not limited to implants and other associated hardware may be included depending on the application. 
     In accordance with another aspect of the present invention, sterile instrumented disposable surgical tools are also provided. The tools are in sterile condition in sterile packaging and are used in the identified surgical procedure. The tools are instrumented with markers that can be visualized during an image guided surgery by a tracking system. 
     In accordance with another aspect of the present invention, an application specific software module is contained on the digital medium. The software module can only be used once and will function only when used in conjunction with the portion of the image guided surgery software that resides on the computer. 
     In accordance with another aspect of the present invention, acoustic, infrared, video camera, or other tracking systems are utilized to determine the location of the instrumented surgical tools. The tracking system can be used to track other accessories e.g., a registration phantom, as well. The tracking system can be incorporated into a separate mobile cart or integrated directly into the operating room infrastructure e.g., lights, ceiling. 
     At a surgical site, the digital medium is removed from the software-integrated disposable kit and inserted into the computer. The software which resides on the computer in conjunction with the software on the digital medium, processes electronic medical diagnostic images, registers the acquired images to the patient&#39;s anatomy, registers the acquired images to any other acquired imaging modalities e.g., fluoroscopy to CT, MRI. The location of the instrumented surgical tool(s) is tracked by simultaneously updating the tool&#39;s virtual representation in the image(s), or any combination or subset thereof, with movement of the tool(s) in physical space. After the surgery, the digital medium and the surgical tool(s) are disposed of as they are disposable and can only be used once. 
     One advantage of the present invention resides in low or no capital cost to hospital and medical facilities for the equipment. 
     Another advantage of the present invention is that it enables automatic upgrade of the image guided surgery software and of the specifications, descriptions, and characteristics of the surgical tools residing on the computer upon insertion of the digital medium. 
     Yet another advantage of the present invention is the assured sterility of the surgical tools, accessories, and any other components of the system contained in the software-integrated disposable kit, which enter the sterile field. 
     Another advantage of the present invention is the assured sharpness and reliable maintenance of any other quality aspects of the surgical tools and guides. 
     Another advantage includes simplified patient billing. 
     Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating a preferred embodiment and are not to be construed as limiting the invention. 
         FIG. 1  is a perspective view of a mobile cart in combination with a computer with peripherals including but not limited to a joystick, a display, accessories including but not limited to cables, and a tracking system in accordance with the present invention; 
         FIG. 2  is a perspective view of a software-integrated disposable kit in accordance with the present invention; and, 
         FIG. 3  is a diagrammatic illustration of a schematic for the computer in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIG. 1 , one embodiment of the invention mentioned herein includes a computer  10  that is mounted in a mobile cart  12  or other convenient location in a surgical suite outside of the sterile field. This may be on the wall or on a hospital cart that is not in use. In the illustrated embodiment, as the computer  10  is inserted into the cart, a series of electrical interconnections are made, including interconnection with a display e.g., a flat screen monitor  14 , interconnection with an electrical wall outlet, backup power supply unit contained within the cart, or some combination thereof, interconnection with one or several tracking system cameras  16 , and the like. The tracking system cameras  16  for tracking the location of markers including but not limited to acoustic sensors, infrared sensors, and the like, are mounted on mobile carts, suspended from the ceiling of the surgical suite, mounted in conjunction with other equipment in the surgical suite such as the lighting, the operating table, or the like. In one embodiment, the cart  12  includes a port for connecting the computer  10  with the central record storage system of the hospital via a network, a diagnostic imaging device  64 , or other source of electronic images of the patient. In other embodiments, the computer  10  includes a disk, tape, or other media drive for receiving the image information via a portable medium. 
     With reference to  FIG. 2 , for each surgical application, there is a corresponding software-integrated disposable kit  20 . The kit  20  includes a sealed, e.g., shrink-wrapped, carry-case or unit  22  which contains all of the necessary equipment for performing a specific surgical procedure indicated on a label  24  on the outside of the kit. A variety of kits  20  are provided, each labeled for a specific surgical procedure or limited group of closely related surgical procedures. Each kit  20  typically includes the appropriate surgical tools for the corresponding procedure, such as instrumented drill guides  26 ,  28 , instrumented probes  30 , and other accessories as may be appropriate to the selected procedure. The tools are instrumented with markers  32  which are tracked by the cameras  16 , in the preferred embodiment. Additional markers  32  not attached to a tool may be included in the kit  20 . In other embodiments, the markers  32  are acoustic or infrared transmitters whose signals are received by corresponding acoustic or infrared cameras  16 . By tracking the markers  32  with one or several cameras  16 , the current location of each marker  32 , hence the associated tool, is readily determined by well-known triangulation techniques. In other embodiments, more than two cameras  16  or other sensors are provided for improved tracking even when the surgeon temporarily blocks access to one of the markers  32 . Each of the drill guides  26 ,  28 , probes  30 , and other surgical tools and accessories are presterilized and wrapped in peel-open or other sterile packaging. 
     The kit  20  further includes several other components which are commonly used during image guided surgery. These components can include a universal tool tracker  34  which is mounted directly to a fixed location on the tool. The universal tool tracker  34  is used to track standard surgical tools that are not included as part of the kit  20 . A registration phantom  36  that is attached to the operating room table or directly to the imaging device is also included and is used to register an acquired image(s) to the patient&#39;s anatomy. Depending on the surgical procedure, other components may be included such as a head frame  38  with markers for attachment to the patient. All the components contained in the kit  20  are again presterilized and prepackaged in sterile packaging. 
     The kit  20  further includes, but is not limited to, a user input device(s)  40  such as a joystick, mouse or keyboard with which the operator controls the software&#39;s graphic user interface. The user input device(s)  40  and their associated cable(s) are sterile and packaged in sterile packaging. During set-up for the procedure, the sterile packaging is opened and the cable(s) for the user input device(s)  40  is plugged into a corresponding port on the computer  10  or mobile cart  12 . Another embodiment includes a wireless user input device(s) that is recognized by the system, through an infrared port for example on the computer  10  or mobile cart  12 . 
     The kit  20  can further include implants  42  and other surgical accessories that are used in the selected surgical procedure. For example, the kit  20  can include pedicle screws  42 , rods  44 , and mounting clamps  46 , and the like as are appropriate for a surgical procedure on the spine. Different surgical procedures will, of course, have different surgical accessories in the kit  20 . The surgical accessories are sterile and sealed in sterile packaging. 
     The kit  20  further includes a one-time-use digital medium  50 , such as a small high-capacity diskette, CD-ROM, DVD, or the like. The digital medium  50  is configured to be received into a drive  52  in the computer  10 . The diskette  50  contains a portion of the software to be used during a surgical procedure, image processing algorithms specific to the application, dimensions and other specifications of the surgical tools and accessories in the kit  20 , and other information of use during the surgical procedure. 
     With reference to  FIG. 3 , the computer  10  may include triangulation or tracking software and base or low-level graphics and other processing software  60 . A video-grabber card or other similar input/output device for capturing still-images or live video includes an input/output port and/or interface  62  for receiving electronic images directly from an imaging device  64 . Images can also be received through the computer network port by accessing central record keeping via the hospital&#39;s network. Optionally, the computer  10  may include a drive for reading the electronic image information obtained from the imaging device  64  from disk, tape, or other similar media. The computer  10  also includes a graphics card or the like with a port and/or interface  66  for connecting to the display  14 . Likewise, the computer  10  includes a port and/or interface  68  for interconnection with the user input device  40 . The computer  10  may also contain a port, an infrared port for example, for wireless connection to the user input device(s). The computer  10  further includes a port and/or interface assembly  70 , which interfaces the tracking system&#39;s cameras  16  with the tracking software. 
     The one-time-use digital medium  50 , in the preferred embodiment is a mini-diskette, which includes information useful for a specific surgical application. The medium contains an area for high-level graphics processing software  72  with the most recently revised algorithms for the graphics processes which are specific to the selected surgical procedure. The disks for different surgical procedures may have different high-level graphics processing software and information. The high-level graphics processing software  72  interacts with the low-level graphic processing software  60  to enable the computer  10  to perform the image and graphics processing which it may be called upon to perform during the selected surgical procedure. Various other electronic keys, including media such as CD-ROM and DVD for example, for enabling the computer  10  for image guided surgery are also contemplated. 
     The digital medium  50  further includes an area  74  for software which describes tool specifications. That is, software to describe the specifications of each of the tools, probes, guides, and any other necessary accessories in the kit. In conjunction with the tool(s) physical specifications, markers  32 , and the tracking system&#39;s cameras  16 , the image guided surgery software recognizes the tool and correlates its position, trajectory, end point, and any other necessary characteristics in physical space with it&#39;s virtual representation on the display  14 . 
     The digital medium  50  further includes an area  76  for 3D virtual representations, images, or information, in VRML format for example, of the instrumented tools contained in the kits. These files are used to create 3D virtual representations of each of the surgical tools. The 3D representations of the tools are superimposed on each acquired and registered image. These representations can be in wireframe or fully rendered format, for example, depending on the surgeon&#39;s preference. The 3D surgical tool information or image area  76  is accessed by the software on the computer and the digital medium and manipulated so the tools virtual representation in the image(s) is correlated to its 3D position in physical space as determined by the camera(s)  16 . 
     The digital medium  50  further includes an area  78  for software that describes other information such as instructions with guides concerning common steps taken during the surgical procedure. For example, this section may include software information concerning the depth and diameter of the holes to be tapped for the surgical screws in the kit. It may include information or guidelines for the use or placement of the accessories in the kit, images from a previous or similar procedure, anatomy atlas tables containing information on certain anatomical angles and distances specific to an application, and the like. This portion of the digital medium  50  may also include software for upgrading the low-level graphics processing software  60  to the latest released revision. 
     The invention further includes a means  80  to ensure one-time-use of the digital medium  50 . This means preferably resides in the computer  10 . In one embodiment, this means erases all or part of the digital medium at the end of the procedure. Alternately, the software is encrypted to block reuse. In another embodiment, the digital medium  50  is physically deformed to prevent reuse. After the procedure, the tools and the digital medium  50  are disposed. Alternatively, the tool and the medium  50  are returned to the company for inspection, remanufacture, cleaning, sterilization, and/or repackaging. Alternatively, the digital medium can also be used to store data obtained during surgery i.e., notes, images, etc. In this case, the digital medium  50  is archived. 
     In a preferred marketing procedure, the computer  10  is of limited cost. The computer  10  is sold to the hospitals at nominal or no cost. The cost of the computer  10  is recovered by the sale of the single use kits  20 , the price of which is gauged to cover the cost of maintaining the computer  10  as well as the tools and accessories. This business model eliminates the traditional capital equipment sale process for conventional image guided surgery equipment. It also facilitates patient billing. 
     The invention has been described with reference to the preferred embodiment. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.