Abstract: Disclosed is a system and method for diagnosing a perfusion condition in the human brain. The process used includes measuring parameter values at a location of interest in one hemisphere and determining relative differences between those measured values against values measured at a substantially symmetrically opposite location in the other hemisphere. These relative differences are used to generate a composite output which is displayed using different colors. Each color is reflective of a different tissue state, e.g., ischemic core, penumbra, etc. If the substantially symmetrically opposite location is abnormal, and thus, is not a good reference, an alternative reference location which is not substantially symmetrically opposite the location of interest is chosen, and a relative difference map generated. Alternatively, an absolute value map can be generated.

Abstract: A method and apparatus for detecting position and orientation of catheter distal magnetic element end while moving in a patient's heart is described. The apparatus includes magnetic sensors for to detect the magnetic field of a generated by the catheter tip. Each sensor transmits the field magnitude and direction to a detection unit, which filters the signals and removes other field sources, such as generated by CGCI coils and external medical hardware. The method allows the measurements of magnitude corresponding to the catheter tip distance from the sensor and the orientation of the field showing the magnetic tip orientation. Since the tip's magnetic field is not necessarily symmetric, the position and orientation computation technique are not independent of each other. Hence, an iterative calculation is used to converge to a solution. The method of determining tip position is calculated by triangulation from each sensor.

Abstract: A method and apparatus for registering physical space to image space is disclosed. The system allows for determining fiducial markers as pixels or voxels in image data. The system can correlate and register the determined fiducial points with fiducial markers in physical space.

Abstract: Candidate character strings representing objects disposed in a work cell, models for robot operation instructions which has variable parts, and robot commands related to the objects are defined in advance. By inputting a query such as ‘Workpiece 1 ?’ by voice, the object concerned is indicated by a display color so that the work cell can be confirmed. Models for operation instructions and a program to be edited are displayed to allow an operator to select the portion to be edited. When an operation instruction is input by voice in the model pattern, candidate character strings are assigned to the variable parts of the model. A completed statement that matches the voice-recognized statement is found, the robot operation commands defined for the objects are displayed, and the robot operation is displayed on the screen. The operation commands are inserted at the desired location in the program.

Abstract: A fiducial marker for use in the body of a living being to enable the localization of targeted internal tissue. The implant is in the form of an elongated, e.g., rod-like, spacer located between pair of end members, e.g., gold cylinders, and held together by an elongated sleeve, e.g., a heat-shrinkable sleeve. When so connected portions of the end members are exposed, i.e., extend beyond the ends of the sleeve. The outer surface of the exposed portions of each of the end members is textured, e.g., grooved, to provide resistance to migration when the marker is implanted. The spacer and the sleeve are each be formed of an absorbable material.

Abstract: A method for navigating a medical device to an anatomical surface within a subject to perform electro-anatomical mapping using a magnetic navigation system is provided that includes importing a pre-operative image data set of an anatomical surface in the subject's body into a localization system. One or more control parameters are applied to the magnetic navigation system to drive the medical device to one or more points of tissue contact, from the locations of which a geometric anatomical map can be created and registered with the pre-operative anatomical image. The pre-operative anatomical surface image and a representation of the geometric anatomical map are displayed relative to one another, such that a user may select a location on the displayed pre-operative anatomical image to navigate the medical device towards.

Abstract: A system and method are provided for obtaining registration of a localization system's three-dimensional coordinates for a plurality of markers having known locations to the two-dimensional coordinates for the plurality of reference markers obtained from a single X-ray image. The method for registering a navigational system with a localization system having a plurality of reference markers includes determining the three-dimensional coordinates of the locations of a plurality of reference markers within the localization coordinate system, and providing a single two-dimensional X-ray image that includes a two dimensional location of the plurality of markers. The method further includes determining a coordinate transformation for obtaining a best fit registration of the localization system's three-dimensional coordinates to the two-dimensional coordinates obtained from the single X-ray image, for at least one reference marker location.

Abstract: A new and improved method for tracking and/or spatial localization of an invasive device in Magnetic Resonance Imaging (MRI) is provided. The invention includes providing an invasive device including a marker having a chemically shifted signal source with a resonant frequency different from the chemical species of the subject to be imaged, applying a pulse sequence, detecting the resulting RF magnetic resonance signals, and determining the 3D coordinates of the marker. The invention also includes generating scan planes and reconstructing an image from the detected signals to generate an image having the marker contrasted from the subject. The invasive device includes a marker having a chemically shifted signal source which has a resonant frequency different from the chemical species of the subject to be imaged for use in tracking the device during imaging.

Abstract: A delivery apparatus for the percutaneous placement of a medical device at an area of interest in a tissue mass comprises an introducer comprising a cannula having an insertion tip, an expulsion opening near the insertion tip, and a medical device within the cannula comprising an imaging element, and a guide element connected to the imaging element and having a separable portion, and wherein the cannula is inserted into the tissue mass such that the medical device can be expelled through the expulsion opening into the tissue mass, and when the cannula is withdrawn from the tissue mass, the imaging element is placed within the tissue mass at the area of interest, and at least part of the guide element extends exteriorly of the tissue mass, and when the separable portion is separated from the guide element, no part of the guide element extends exteriorly of the tissue mass.

Abstract: A system for measuring the position of a hand-held tool relative to a body in six degrees of freedom employs a camera attached via a mechanical linkage to the tool so that the camera moves together with the proximal portion of the tool and has a field of view including the distal end of the tool. A processing system processes images from the camera to determine a position of at least part of the tool. By employing optically identifiable fiducial reference points defined on the external surface of the body, a projection of the tool tip position onto a plane containing the target can be derived and displayed together with the target position, thereby facilitating guiding the tool to the target.

Abstract: Aspects include methods and apparatuses for effecting change over time in one or more measured regions of a body using a plurality of data sets obtained by analysis of applied signals to said region and effecting a change in treatment protocol. The method may include transmitting and receiving one or more of electromagnetic wave signals, applied acoustic wave signals and electrical signals transmitted through or reflected off of a portion of the measured body region. Some aspects may include determining a change in tissue structure, or a change in tissue content.

Abstract: A deformable marker device for adapting to a human or animal body includes a plurality of marker elements, and a connecting device that connects at least some marker elements of the plurality of marker elements to each other. The connecting device enables the at least some marker elements to be moved relative to each other so as to adapt a shape of the marker device to a course of a curved surface.

Abstract: A technique for automatically labeling a CT image of the brain with anatomical information. The anatomical information is obtained from an atlas of the brain prepared from an MR image of the brain. The atlas contains image data that is referenced to the Talairach coordinate system. The atlas is aligned to the CT image and the coordinate system of the CT image data is transformed to the Talairach coordinate system. The alignment of the CT image and the atlas is performed using anatomical landmarks that are visible on both the CT image and the atlas. The CT image is then labeled automatically with the anatomical information in the atlas.

Abstract: The invention relates to a medical system comprising a detection device for detecting an object in at least two dimensions by x-rays. The detection device is constructed to detect the object and to produce data comprising a 2D data record or a sequence of 2D data records over time representing the object in a projection through the object in two dimensions and to output the data. The medical system comprises at least one storage device with a data input actively connected to the detection device and which is constructed to receive the data at the input side and to write on a storage medium, in particular a portable storage medium, in such a way that the storage medium represents the data so it can be read out again. The medical system is constructed to digitally transmit the data from the detection device through to the storage device.

Abstract: A system and method of determining a measure of accuracy of a registration mapping combining data indicative of spatial positions in a three-dimensional operating space and imaging data acquired with an imaging device located in a position and orientation in operating space is provided. A phantom is brought into a first pose, wherein the phantom is at least in partial view of the imaging device located in a second pose, the phantom comprising a marker assembly that can be imaged by the imaging device. Image data of the marker assembly of the phantom is acquired with the imaging device in the second pose. Imaged markers in the acquired image data of the marker assembly are located, and mapped markers are obtained by submitting spatial positions of the markers in the marker assembly of the phantom in the first pose to the registration mapping using the second pose as the imaging pose.

Abstract: Certain embodiments of the present invention provide methods and systems for imaging system calibration using a field replaceable unit. Certain embodiments provide a field replaceable unit for imaging system calibration. The unit includes an array of radio opaque fiducials arranged for use in image calibration for an imaging system. The unit also includes a plurality of receivers positioned around a periphery of a detector in the imaging system for use in navigation calibration for the imaging system. The unit further includes a connection for providing data regarding image calibration and navigation calibration to a processor. Additionally, the unit includes a frame for positioning the array of radio opaque fiducials and the plurality of receivers embedded in a concave target with respect to a detector in the imaging system.

Abstract: A high performance imaging system for diffuse optical tomography is disclosed. A dense grid utilizing sources, e.g., light emitting diodes (“LEDs”), that achieve high performance at high speed with a high dynamic range and low inter-channel crosstalk are complemented by a system of discrete, isolated receivers, e.g., avalanche photodiodes (“APDs”). The source channels have dedicated reconfigurable encoding control signals, and the detector channels have reconfigurable decoding, allowing maximum flexibility and optimal mixtures of frequency and time encoding and decoding. Each detector channel is analyzed by dedicated, isolated, high-bandwidth receiver circuitry so that no channel gain switching is necessary. The resulting improvements to DOT system performance, e.g., increased dynamic range and decreased crosstalk, enable higher density imaging arrays and provide significantly enhanced DOT image quality.

Abstract: A portable orthovoltage radiotherapy system is described that is configured to deliver a therapeutic dose of radiation to a target structure in a patient. In some embodiments, inflammatory ocular disorders are treated, specifically macular degeneration. In some embodiments, the ocular structures are placed in a global coordinate system based on ocular imaging. In some embodiments, the ocular structures inside the global coordinate system lead to direction of an automated positioning system that is directed based on the ocular structures within the coordinate system.

Abstract: A marker navigation system for determining a length of at least one flexible instrument having a first end and a second end, wherein portions of the at least one flexible instrument can be both linear and curved, the marker navigation system includes: a holder for holding the instrument, said holder comprising a first marker device, wherein the second end of the instrument is attached to the holder; a calibrating apparatus including a second marker device and at least one opening for inserting the first end of the instrument, said at least one opening having a predetermined shape and depth; a detection device for detecting a first location of the first marker device and a second location of the second marker device; and a data processing device for determining the length of the instrument.

Abstract: An image analysis system comprising: (a) an image input module adapted to receive a medical image; and (b) an analytic module adapted to segment the image, identify a plurality of vertebrae and label each vertebra.

Abstract: A method and apparatus for registering a pelvis of a subject in a lateral position are described. The method includes the position of at least a first point and a second point in a first plane parallel to a first cardinal plane of the pelvis. Then the position of at least a third point and a fourth point in a second plane parallel to a second cardinal plane of the pelvis are determined, in which the second plane is perpendicular to the first plane. Then the position of a third cardinal plane of the pelvis is determined, in which the third cardinal plane is perpendicular to the first cardinal plane and second cardinal plane. The apparatus includes a computer aided surgery system and an instrument trackable by a tracking part of the system.

Abstract: This invention discloses a method and apparatus to deliver medical devices to targeted locations within human tissues using imaging data. The method enables the target location to be obtained from one imaging system, followed by the use of a second imaging system to verify the final position of the device. In particular, the invention discloses a method based on the initial identification of tissue targets using MR imaging, followed by the use of ultrasound imaging to verify and monitor accurate needle positioning. The invention can be used for acquiring biopsy samples to determine the grade and stage of cancer in various tissues including the brain, breast, abdomen, spine, liver, and kidney. The method is also useful for delivery of markers to a specific site to facilitate surgical removal of diseased tissue, or for the targeted delivery of applicators that destroy diseased tissues in-situ.

Abstract: A medical treatment system is described having an imaging device and a patient examination table. At least one of the imaging device or the patient table has a motorized or hydraulic mechanism for moving the imaging device and the patient examination table relative to each other. A processor tracks the position of a catheter or a bolus of contrast enhancing material so that the catheter or bolus is maintained within the field of view of the imaging system, or within the displayed image where the images have been previously obtained. The position of the catheter may be determined by image analysis or magnetic or acoustic means, and the position of the bolus may be obtained by image analysis.

Abstract: A system for video based registration between images during a skeletal medical procedure, the system includes a stereoscopic camera, a two dimensional image detector and a registration processor, the stereoscopic camera is associated with a stereoscopic coordinate system, the stereoscopic camera acquires a stereoscopic image pair of a fiducial mark, the fiducial mark is fixed onto a skeletal structure, a first fiducial representation of the fiducial mark is apparent on the stereoscopic image pair, the 2D image detector is associated with a 2D coordinate system and acquires at least two substantially different images of the skeletal structure, a second fiducial representation of the fiducial mark and a first skeletal representation of the skeletal structure is apparent on the two substantially different 2D images, the registration processor is coupled with the stereoscopic camera and with the 2D image detector and registers the stereoscopic coordinate system with a three dimensional (3D) coordinate system asso

Abstract: An apparatus can be used to navigate a planned procedure. The plan for the procedure can be based on various elements, such as anatomical landmarks that can be used to determine anatomical targets of a patient.

Abstract: In accordance with an embodiment of the present invention, an image guided interventional system enables registration of a patient, preferably automatically and without an explicit patient registration step, to newly acquired images as the patient is moved out of the imager. Only one set of images has to be taken. The position of the needle or other instrument is tracked using a tracking system and its position continually displayed and updated with respect to the images. Therefore, there is no need to take additional images for purposes of tracking progress of an instrument being inserted into a patient. Avoiding additional scans saves time and reduces exposure of the patient to radiation.

Abstract: An imaging system for use in medical intervention procedure planning includes a medical scanner system for generating a volume of cardiac image data, a data acquisition system for acquiring the volume of cardiac image data, an image generation system for generating a viewable image from the volume of cardiac image data, a database for storing information from the data acquisition and image generation systems, an operator interface system for managing the medical scanner system, the data acquisition system, the image generation system, and the database, and a post-processing system for analyzing the volume of cardiac image data, displaying the viewable image and being responsive to the operator interface system. The operator interface system includes instructions for using the volume of cardiac image data and the viewable image for bi-ventricular pacing planning, atrial fibrillation procedure planning, or atrial flutter procedure planning.

Abstract: A medical apparatus has a data processing device for storing an image dataset of the body of a subject and a navigation system for determining the position of a medical instrument relative to the body of the subject. At least one bone fragment is shown in the image represented by the image dataset, the image of the one bone fragment being segmented with a computer. The bone fragment is to be grasped and set with the medical instrument. The data processing device also determines the modified position of the bone fragment on the basis of the position of the medical instrument relative to the body of the subject determined with the navigation system, and displays the modified position in the image.

Abstract: A fiducial implant for use in the body of a living being to enable the localization, e.g., radiographic, of targeted internal tissue. The implant is in the form of an elongated, e.g., rod-like, central section and a pair of end sections, each of said end sections is arranged so that it can be readily imaged by a first type of imaging, e.g, X-ray imaging, ultrasonic imaging and magnetic resonance imaging. The implant can be inserted via a needle or cannula into targeted tissue so that when exposed to the first type of imaging the bulbous ends of the implant can be readily discerned.

Abstract: A localization device display method and apparatus for displaying different views, e.g., of different magnification, based on the proximity of the tip of a pointer tracked by the localization device to a reference location identified by the localization device. The display method and apparatus may be incorporated into a surgical navigation system for use in identifying a location for drilling a femoral tunnel in an ACL repair procedure.

Abstract: A stereotactic navigation system for navigating an instrument to a target within a patient may include a stereotactic head frame, an imaging device, a tracking device, a controller and a display. The stereotactic head frame is coupled to the patient and is used to assist in guiding the instrument to the target. The imaging device captures image data of the patient and of the stereotactic head frame. The tracking device is used to track the position of the instrument relative to the stereotactic head frame. The controller receives the image data from the imaging device and identifies the stereotactic head frame in the image data and automatically registers the image data with navigable patient space upon identifying the stereotactic head frame, while the display displays the image data.

Abstract: A method and apparatus to immobilize a breast of a patient and position a fiducial about the exterior of the breast. The apparatus includes a cup forming a cavity to accept the breast of the patient within the cup. The apparatus also includes a fiducial marker coupled to the cup. The fiducial marker has a spatial relationship with a target region of the breast.

Abstract: A method of creating 3D models to be used for cardiac interventional procedure planning. Acquisition data is obtained from a medical imaging system and cardiac image data is created in response to the acquisition data. A 3D model is created in response to the cardiac image data and three anatomical landmarks are identified on the 3D model. The 3D model is sent to an interventional system where the 3D model is in a format that can be imported and registered with the interventional system.

Abstract: A method for mapping higher brain function comprises an fMRI mapping step S1 to map a brain function of the subject TP by fMRI, a head portion structural image acquisition step S3 to acquire a head portion structural image IMGs by an MRI system in a state that a headgear HC having a marker is mounted on the head portion of the subject TP, a three-dimensional image combining step S4 to create a three-dimensionally combined image IMGfs by combining the head portion structural image IMGs and the brain functional image IMGf obtained by the fMRI mapping step S1, an optical probe mounting step S5 to specify positions on the headgear HC where optical probes PR1, PR2 are mounted based on the three-dimensionally combined image IMGfs and to mount the optical probes PR1, PR2 at the specified positions and an NIRS measuring step S6 to conduct the NIRS by a NIRS method in a state that the headgear HC loaded with the optical probes PR1, PR2 is mounted on the head portion of the subject TP.

Abstract: An apparatus and a method for performing a medical procedure is disclosed. In an embodiment for an apparatus of the present invention, the apparatus includes a positioning system and a resection device disposed within the positioning system. The positioning system includes an imaging device, a video processor coupled to the imaging device, a computer coupled to the video processor, and a video display coupled to the computer. In an embodiment for a method of practicing the present invention, the method includes the steps of creating an image of a lesion within a patient's body on an imaging device. Data representative of the lesion image is processed by a video processor. Tissue margins around the lesion are defined by a processor based on the processed data representative of the lesion image and a resection device is operated during a resection procedure within the patient's body based upon the defined tissue margins.

Abstract: The invention relates to a system for the combined shadow-free illumination of a pre-definable area and for referencing three-dimensional spatial co-ordinates, and to an active or passive referencing system, each in particular for referencing surgical or medical instruments. The system is characterized in that at least two cameras and the light source (operation lamp) are held together such that the optical signals detected by the cameras, for referencing three-dimensional spatial co-ordinates in the area illuminated by the light source, can be evaluated. Since the field of view of the light source, in its conventional use, is not obscured or only negligibly obscured, this field of view can simultaneously be used for optical navigation by the cameras held together with the light source. In accordance with the invention, the cameras are automatically aligned optimally for optical navigation. The cameras can be rigidly or flexibly connected to the light source.

Abstract: A remote controlled robot system that includes a robot and a remote control station. A user can control movement of the robot from the remote control station. The remote control station may generate robot control commands that are transmitted through a broadband network. The robot has a camera that generates video images that are transmitted to the remote control station through the network. The user can control movement of the robot while viewing the video images provided by the robot camera. The robot can automatically stop movement if it does not receive a robot control command within a time interval. The remote control station may transmit a stop command to the robot if the station does not receive an updated video image within a time interval.

Abstract: A robot system is provided and includes an autonomous mobile robot. In the system in which monitoring is performed using the autonomous mobile robot which travels along a predetermined path, an interval between the time when a user requests transmission of images and the time when the user obtains the images may be reduced. The autonomous mobile robot travels along a predetermined path at predetermined times, a camera takes photographs at predetermined locations during the travel along the predetermined path, images taken by the camera are stored, and the stored images are sent to a requesting cell phone in response to a transmission request from the cell phone.

Abstract: A manual-mode operating system for a robot provided with an end-effector.

Abstract: A robotic storage library is provided for reducing the transition time to reach an operational state following a transition from a power-off to a power-on state. The robotic storage library can generally include a transport unit for moving data cartridges, or other storage elements, between a location in a shelf system and a drive, or data transfer interface, to complete storage operations for a host computer. The library can further include a controller for causing an audit to be performed to create an inventory of the locations. The audit can be stored in nonvolatile memory prior to the power transition. The inventory information can be transmitted to a host computer after the power transition.

Abstract: An assembling method and an apparatus for carrying out the method capable of efficiently, reliably and easily detecting an insertion and fitting position, for easy automatic assembly. In case a rod-like workpiece is inserted into a hole in an object, an insertable range is determined based an amount of clearance between the workpiece and the hole, an amount of chamfering of the hole, etc. The insertable range is defined as within a range centered at a hole center position 3cp and having a radium of r. A workpiece center position is indicated by 1cp. While the workpiece is moved once throughout a search range (XL-XU) in the X-axis direction, it is moved in the Y-axis direction by an amount equal to or less than an insertable range amount 2r. As shown by a dotted line, the workpiece center 1cp passes without fail through the insertable range during the motion throughout the search range (XL-XU, YL-YU).

Abstract: A robotic system that includes a plurality of robots that are linked to a plurality of remote stations. The robots have an input device and software that allows control of another robot. This allows an operator in close physical proximity to a robot to operate another robot. Each robot can be either a master or slave device.

Abstract: A robotic system that includes a remote controlled robot. The robot may include a camera, a monitor and a holonomic platform all attached to a robot housing. The robot may be controlled by a remote control station that also has a camera and a monitor. The remote control station may be linked to a base station that is wirelessly coupled to the robot. The cameras and monitors allow a care giver at the remote location to monitor and care for a patient through the robot. The holonomic platform allows the robot to move about a home or facility to locate and/or follow a patient.

Abstract: With the beam scanning probe system for surgery, a pointer indicating the observation point of a beam scanning probe is superimposed upon an image of a lesion to be operated on in the head which is obtained via a TV camera or a surgery microscope, and the superimposed image information is registered as such in an image recording device. With the beam scanning probe system for surgery, information of a cytological picture is also registered in the image recording device. With the beam scanning probe system for surgery, the image recording device registers the two image information in a paired fashion. Through this arrangement, the beam scanning probe system for surgery can smoothly locate, for a given cytological picture, a site of a tumor to be treated from which the picture was obtained, which will ease the operation.

Abstract: A robotic system that includes a mobile robot linked to a plurality of remote stations. The robot provides both audio and visual information to the stations. One of the remote stations, a primary station, may control the robot while receiving and providing audio and visual information with the remote controlled robot. The other stations, the secondary stations, may also receive the audio and visual information transmitted between the robot and the primary station. This allows operators of the secondary stations to observe, communicate and be trained through the robot and primary station. Such an approach may reduce the amount of travel required to train personnel.

Abstract: A robotic system that includes a remote controlled robot with at least five degrees of freedom and a teleconferencing function. The robot may include a camera, a monitor and a holonomic platform all attached to a robot housing. The robot may be controlled by a remote control station that also has a camera and a monitor. The remote control station may be linked to a base station that is wirelessly coupled to the robot. The cameras and monitors allow a care giver at the remote location to monitor and care for a patient through the robot. The holonomic platform provides three degrees of freedom to allow the robot to move about a home or facility to locate and/or follow a patient. The robot also has mechanisms to provide at least two degrees of freedom for the camera.

Abstract: A robotic system that includes a remote controlled robot. The robot may include a camera, a monitor and a holonomic platform all attached to a robot housing. The robot may be controlled by a remote control station that also has a camera and a monitor. The remote control station may be linked to a base station that is wirelessly coupled to the robot. The cameras and monitors allow a care giver at the remote location to monitor and care for a patient through the robot. The holonomic platform allows the robot to move about a home or facility to locate and/or follow a patient.

Abstract: A method for monitoring a patient with a robotic system that includes a remote controlled robot. The robot may include a camera, a monitor and a holonomic platform all attached to a robot housing. The robot may be controlled by a remote control station that also has a camera and a monitor. The remote control station may be linked to a base station that is wirelessly coupled to the robot. The cameras and monitors allow a care giver at the remote location to monitor and care for a patient through the robot. The holonomic platform allows the robot to move about a home or facility to locate and/or follow a patient.

Abstract: A registration artifact (10) for use in registering two or more fluoroscopic images includes a plurality of radio opaque spheres (12, 14, 16) and a plurality of trackable markers, such as optical reflectors (20, 22, 24 and 26), mounted to a radio transparent body (11). A tracking system locates the position of registrable artifact using the trackable markers for registering the fluoroscopic images with respect to a known frame of reference.

Abstract: A fluoroscopic image guided surgery system, comprising a C-arm fluoroscope for obtaining fluoroscopic images of an object bone, the C-arm fluoroscope including at least one set of emitters; a reference bar capable of attaching to an object bone, the reference bar including emitters; a surgical instrument for performing an operation, the instrument including emitters; a digitizer system in communication with the at least one set of emitters of the C-arm fluoroscope, the emitters of the reference bar, and the emitters of the surgical instrument so that the digitizer system can determine a position of each of the C-arm fluoroscope, the reference bar, and the surgical instrument; and a single fiducial marker for attachment to an object bone, the single fiducial marker being visible in the fluoroscopic images for determining a position of an object bone relative to the digitizer system.