Automatic medical equipment identification

Abstract

The present invention relates to a medical instrument identification mechanism including a sensor carrier removably positioned within a lumen of a medical instrument. The sensor carrier has at least two localizers, each providing a sensor signal representative of the position and orientation of the localizer. The identification mechanism includes a position detection system that determines the position and orientation of the at least two localizers in a coordinate system of the position detection system from the received sensor signals. The identification mechanism includes a calibration device and a calibration unit, and the calibration device is configured so that the position and orientation in the coordinate system of the position detection system can be determined by the position detection system. The calibration unit calculates a distance between a tip of the medical instrument and the at least one localizer to calibrate the medical instrument. The identification mechanism includes a medical instrument identification unit that determines a lumen length of the medical instrument from the calculated distance and uses the lumen length to identify the medical instrument.

Description

[Technical field]

[0001] The present invention relates to a medical instrument identification mechanism for automatically identifying a medical instrument.The present invention also relates to a method for automatically identifying a medical instrument. [Background technology]

[0002] To assist a surgeon in using a medical instrument in a surgical procedure, it is known to track the position of the medical instrument within a patient's body and display the position of the medical instrument on a monitor, such as on a cross-sectional image of a patient model.

[0003] For this purpose, a surgical navigation system is typically used that includes a position detection system, a monitor, and one or more localizers. The position detection system may be, for example, an optical position detection system, an ultrasound-based position detection system, or an electromagnetic position detection system. In general, the position detection system is configured to determine the position and orientation of the localizer. The localizer may be attached to the medical instrument to enable tracking of the medical instrument by the position detection system.

[0004] As an example, electromagnetic location systems are known that have a field generator for generating an alternating electromagnetic field. Medical instruments used with electromagnetic location systems typically include a localizer with one or more sensor coils.

[0005] When exposed to an alternating electromagnetic field, voltages are induced in the sensor coils of the localizer that depend on the position and orientation of the respective sensor coil within the alternating electromagnetic field. Using a position detection system, sensor signals representative of the induced voltages can be tapped from the sensor coils and analyzed to determine the position and orientation of the localizer. Typically, the position and orientation of a medical instrument localizer is determined relative to the position and orientation of a reference localizer, also called a patient localizer. The reference localizer also contains sensor coils and remains fixed relative to the patient.

[0006] In order to calculate the position and orientation of a medical instrument with a localizer relative to a position detection system, it is often necessary to calibrate the position of the tip of the medical instrument to the position of the localizer. For this purpose, a calibration device is usually used that has a known position and orientation relative to the position detection system. For example, the calibration device may include a localizer whose position and orientation can also be determined by the position detection system. By calibration, a transformation function (also called a calibration matrix) may be established that represents the spatial relationship of the position and orientation between the localizer of the medical instrument and the tip of the medical instrument. The established transformation function may be used in navigated procedures to display the position of the tip of the medical instrument in a cross-sectional image of a patient model on a monitor.

[0007] To display the position of the medical instruments in the cross-sectional images of the patient model on the monitor of the navigation system, it is usually necessary to perform image registration of the patient model to the patient. In many cases, the patient model is a topographical image generated from 2-, 3- or 4-dimensional images of the patient obtained preoperatively by tomography, for example by computed tomography (CT), magnetic resonance imaging (MRI) or C-arm X-ray imaging. Image registration generally refers to obtaining a spatial correlation between the position and orientation of the patient in real space (also called patient space) and the patient model, which is initially defined in coordinates in the respective coordinate systems of the 2-, 3- or 4-dimensional images used to generate the patient model.

[0008] Once the medical instrument is calibrated and the patient model is aligned, the position of the medical instrument can be displayed on cross-sectional images of the model to visually assist the surgeon in navigating the medical instrument. Summary of the Invention [Problem to be solved by the invention]

[0009] It is an object of the present invention to provide a medical instrument identification mechanism capable of automatically identifying a medical instrument.It is also an object of the present invention to provide a method for automatically identifying a medical instrument. [Means for solving the problem]

[0010] According to the present invention, a medical instrument identification mechanism is proposed which includes at least a sensor carrier with a localizer, a position detection system for determining the position and orientation of the localizer, a calibration device which serves as a calibration standard, a calibration unit for calibrating a medical instrument with the sensor carrier, and a medical instrument identification unit for identifying the medical instrument.

[0011] In particular, the sensor carrier is configured to be removably disposed within the lumen of the medical instrument. The sensor carrier has at least two localizers, each configured to provide a sensor signal representative of a position and orientation of the respective localizer. The medical instrument carrying the sensor carrier may be connected to a position detection system. When the sensor carrier is disposed within the lumen of the medical instrument, the position and orientation of the localizers of the sensor carrier may be determined by the position detection system from the provided sensor signals. The position detection system may calculate the position and orientation of the medical instrument from the determined positions and orientations of the localizers of the sensor carrier.

[0012] Preferably, a first one of the localizers of the sensor carrier is positioned at, or at least near, the distal end of the sensor carrier, i.e. at a distance of 5 mm or less from the distal end of the sensor carrier, and a second one of the localizers is positioned at a distance from the first localizer towards the proximal end of the sensor carrier.

[0013] Preferably, at least the first localizer and the second localizer of the sensor carrier are each configured to function as a 5DOF sensor. Preferably, or in combination, at least two localizers are configured to function as a 5DOF sensor. A 5DOF sensor can be realized by using a sensor coil.

[0014] If the localizer includes one or more sensor coils exposed to an alternating electromagnetic field, a sensor signal can be tapped from each sensor coil representing the position and orientation of the respective sensor coil in the electromagnetic field. The tapped sensor signal can be transmitted to a location detection system by a wired or wireless connection.

[0015] The position detection system of the medical instrument identification mechanism is configured to determine the position and orientation of the at least two localizers in a coordinate system of the position detection system from the received sensor signals. Preferably, the position detection system is an electromagnetic position detection system including a field generator for generating an alternating electromagnetic field and a signal processing unit for processing the sensor signals. The position and orientation of the at least two localizers, each having one or more sensor coils, can be determined in the alternating electromagnetic field from tapped sensor signals representing voltages induced in the sensor coils by the electromagnetic field. The signal processing unit of the position detection system typically includes an analog-to-digital converter and a digital signal processor.

[0016] To connect the medical instrument to the electromagnetic position detection system, at least one of the localizers of the sensor carrier preferably includes at least one sensor coil. With one sensor coil, only five degrees of freedom (DOF) can be determined. Six degrees of freedom, i.e. rotation around the longitudinal axis of the sensor coil, cannot be determined. A 6DOF sensor can be implemented such that the localizer of the sensor carrier includes at least two sensor coils arranged at an angle to each other, for example orthogonally. A 6DOF sensor can also be implemented such that the sensor carrier has two localizers, each of the two localizers having a sensor coil, and the sensor coils of the localizers are arranged such that their longitudinal axes form a non-zero angle, preferably an angle of 90 degrees.

[0017] The sensor carrier may also include at least a third localizer configured to provide a sensor signal representative of a position and orientation of the third localizer. Preferably, the third localizer is located a distance away from the first and second localizers towards a proximal end of the sensor carrier. Preferably, the third localizer is located at or at least near the proximal end of the sensor carrier.

[0018] At least two localizers, alone or in combination with at least a third localizer, can also be used to detect bending. If the sensor carrier is inserted into the lumen of a rigid medical instrument, during the course of insertion, changes in orientation and / or position of the localizers relative to one another can be detected, and the detected changes can be used to determine bending, i.e. angles, in the medical instrument. Preferably, when a change in orientation and / or position of the localizers is detected, for example by the position detection system, a warning signal is displayed by the position detection system on a monitor.

[0019] In particular, when the sensor carrier is placed in the lumen of a medical instrument that has at least one angle (corner) along the length of its lumen, the determined positions and orientations of the three localizers allow the angle of the medical instrument to be calculated. In many cases, the determined angle is characteristic of a particular medical instrument and can be used to identify the medical instrument in which the sensor carrier with the medical instrument identification unit is placed. For example, when the sensor carrier with at least three localizers is placed in the lumen of an endoscope, preferably the third localizer is placed at the angled access port. Usually, the angle between the access port and other parts of the endoscope is characteristic of the endoscope itself. From the determined positions and orientations of the third localizer and at least one of the at least two localizers, respectively, the angle of the endoscope is calculated by the position detection system and / or the calibration unit and used by the medical instrument identification unit to identify the endoscope.

[0020] If the sensor carrier includes a third localizer, the third localizer is preferably arranged at or at least near the proximal end of the sensor carrier. In case of a sensor carrier with a third sensor carrier arranged at or near the proximal end, the position and orientation of the third localizer is preferably used by the medical instrument identification unit for identifying the medical instrument and / or by the position detection system for calculating the sixth degree of freedom of the at least two localizers arranged in the distal end region of the medical instrument. If the localizer includes a sensor coil, the calculation of the sixth degree of freedom of the at least two localizers arranged in the distal end region of the medical instrument can be achieved by the position detection system, especially if the longitudinal axis of the third localizer has an angle with respect to the longitudinal axes of the at least two localizers, respectively.

[0021] The distance between the proximal and distal ends of the sensor carrier, which is placed within the lumens of various medical instruments used during navigated procedures, is preferably 10 cm to 200 cm, in particular 15 cm to 150 cm, more preferably 20 cm to 100 cm. The outer diameter of the sensor carrier is preferably 3 mm or less, in particular 1.5 mm or less, more preferably 1 mm or less.

[0022] Preferably, the sensor carrier includes a hypotube extending from a distal end to a proximal end of the sensor carrier and containing the at least two localizers of the sensor carrier. Preferably, the hypotube containing the at least two localizers is configured to provide mechanical stability to the sensor carrier and to protect the localizers from external influences.

[0023] Suitable materials from which the hypotube of the sensor carrier can be made include, for example, polyurethane (PVR), polyethylene, silicone rubber or polyetheretherketone (PEEK), nitinol, nitinol alloys, or stainless steel. Typically, a hypotube is a long metal tube with micro-engineered features along its length that provide the hypotube with desirable mechanical properties. A sensor carrier having a hypotube made from one of these materials is advantageous in that it can be repeatedly sterilized and is biocompatible.

[0024] The sensor carrier can be used to connect a commonly known medical instrument having a lumen (e.g. a lumen originally provided for guiding a wire) to a position detection system. For this purpose, the sensor carrier is inserted into the lumen of the medical instrument. When using the deployed sensor carrier, the medical instrument can be connected to the position detection system and used together with the position detection system in a navigated procedure. In particular, during a navigated procedure, the position of the medical instrument relative to the position detection system can be calculated from the determined positions and orientations of at least two localizers equipped with the position detection system. The calculated position of the medical instrument can be displayed on a cross-sectional image of a patient model on a monitor connected to the position detection system to assist the surgeon in guiding the medical instrument inside the patient's body. After completion of the navigated procedure, the sensor carrier can be removed from the lumen of the medical instrument, and the lumen can be used as a working channel for other medical instruments, such as drills or forceps.

[0025] Medical instruments that typically have lumens in which a sensor carrier can be placed to connect the medical instrument to a position detection system are, for example, catheters, biopsy needles, access needles, and cannulated instruments (e.g., Jamshidi needles, taps, screwdrivers, and bone screws such as pedicle screws that can be placed by a screwdriver). Such medical instruments with a sensor carrier placed in their respective lumens can be automatically identified by using a medical instrument identification mechanism.

[0026] Further medical instruments that may be equipped with a sensor carrier and thus automatically identifiable using the medical instrument identification mechanism are medical instruments that generally do not have a lumen but have one retrofitted or that are originally manufactured with a lumen suitable for inserting the sensor carrier in. Such medical instruments may be, for example, a scalpel, a surgical saw (e.g., a bone saw), a bone file, a cautery, or a forceps.

[0027] The at least two localizers provided at the distal end of the sensor carrier may be configured to implement and / or be treated as one or separate sensors. When the sensor carrier is disposed within the lumen of the medical instrument, the position of the first localizer and the position of the second localizer along the longitudinal axis of the medical instrument may be used to calculate a virtual longitudinal axis between the two localizers by drawing an imaginary line connecting the two central positions of the localizers, creating a relatively stable and accurate virtual axis of the sensor carrier and the medical instrument.

[0028] When the sensor carrier is arranged in the lumen of the medical instrument, a virtual longitudinal axis of the medical instrument can advantageously be determined by the position detection system and / or the calibration unit based on the positions and / or orientations of at least two localizers of the sensor carrier. The virtual longitudinal axis of the medical instrument is preferably an axis that intersects the positions of the at least two localizers of the arranged sensor carrier. The virtual longitudinal axis of the medical instrument is defined in the coordinate system of the position detection system based on the positions and / or orientations of the localizers. The physical instrument axis is defined by coordinates of real space.

[0029] Advantageously, the use of at least two localizer positions to determine the virtual longitudinal axis of the medical instrument can reduce, among other things, angular errors due to physical misalignment of the sensor carrier within the lumen of the medical instrument to less than 1 degree, which advantageously allows the medical instrument to maintain a stable central axis as it is rotated, for example, during a navigated procedure.

[0030] Generally, it is not necessary to use the orientations (and thus only the positions) of the at least two localizers of the sensor carrier to determine the virtual longitudinal axis of the medical instrument, however the calibration unit and / or the position detection system may be configured to also use the orientations of the at least two localizers in addition to or instead of the positions of the localizers to determine the virtual longitudinal axis.

[0031] According to the positions and / or orientations of the at least two localizers, a spatial relationship between the virtual longitudinal axis of the medical instrument and the physical longitudinal axis of the medical instrument can be determined by the position detection system and / or the calibration unit, thereby allowing to define and ensure the accuracy of the virtual longitudinal axis of the medical instrument relative to the physical longitudinal axis of the medical instrument based on the positions and / or orientations of the localizers, respectively.

[0032] In the sensor carrier, the at least two localizers are preferably arranged at a distance from each other, the distance being selected depending on the shape of the particular medical instrument of the surgical kit. Preferably, the distance between a first localizer and a second localizer of the at least two localizers of the sensor carrier is between 25 cm and 5 cm, in particular between 20 cm and 5 cm, even more preferably between 15 cm and 5 cm (e.g. 10 cm). The greater the distance, the more accurate the determination of the virtual longitudinal axis of the medical instrument. Preferably, the at least two localizers are arranged in a distal end region of the sensor carrier, the distal end region extending from the distal end of the sensor carrier to a proximal end of the localizer of the at least two localizers that is arranged closer to the proximal end of the sensor carrier. In other words, the distal end region preferably includes a section of the sensor carrier that extends between the distal end of the sensor carrier and the proximal end of the localizer of the at least two localizers that is arranged closer to the proximal end of the sensor carrier.

[0033] Preferably, the calibration unit and / or the position detection system are configured to determine a position of a distal end of the medical instrument within the lumen in which the sensor carrier is disposed by extrapolating a virtual longitudinal axis of the medical instrument from a distal end of the disposed sensor carrier. The calibration unit may be configured to calibrate the medical instrument using the position of the distal end of the medical instrument determined by extrapolation. The position detection system may be configured to visualize a position of the tip of the medical instrument in the cross-sectional image on the monitor using the extrapolated position of the medical instrument.

[0034] In addition to automatic instrument identification, the position detection system can be used to visualize the position and orientation of the medical instrument relative to the patient's body parts by calculating the virtual longitudinal axis of the medical instrument and displaying it in a cross-sectional image of the patient model on the monitor. By connecting the position detection system to a medical instrument identification unit, it is possible to obtain which medical instruments have been identified. The position detection system can be configured to automatically adapt the mechanism for displaying a digital representation of the medical instrument on the connected monitor of the identified medical instrument.

[0035] Displaying a virtual longitudinal axis of a medical instrument relative to a patient's body part may be particularly appropriate during navigated procedures, for example when aiming at an anatomical target using a medical instrument (such as an access needle) on which a sensor carrier is placed, from a relatively long distance (e.g., 5 cm to 15 cm).

[0036] The position detection system may be configured to compare the determined positions and orientations of at least two localizers and determine a distortion of the navigation field (e.g., electromagnetic field) based on the comparison. For example, the distortion of the electromagnetic field may be caused by a metal object located near the sensor coil of one of the localizers. Due to the distortion of the electromagnetic field, the position and orientation of each localizer cannot be correctly determined, resulting in an incorrect calculation of the position of the tip of the medical instrument using the position detection system. The position detection system may be configured to perform a plausibility check to identify the localizer when a distortion of the electromagnetic field is detected, so that the position and orientation of the localizer can be reliably determined at that time. For example, the position detection system may be configured to compare the current position and orientation of the localizer with the previously determined position and orientation of the localizer to check whether the position and orientation of the localizer can be reliably determined at that time.

[0037] The calibration device of the medical instrument identification mechanism is configured such that its position and orientation in the coordinate system of the position detection system can be determined by the position detection system. For example, the calibration device may be placed at a location whose coordinates are known in the coordinate system of the position detection system. Similarly, the calibration device may include at least one localizer configured to provide a sensor signal representative of the position and orientation of the localizer.

[0038] The calibration device may have different calibration areas advantageously designed for calibration of different medical instruments (e.g., adapted to the shapes of different medical instruments). The different calibration areas may be implemented by visual indicators on the calibration device. The calibration unit may be configured to detect which of the different calibration areas contacts the tip of the medical instrument. The medical instrument identification unit may be configured to identify the medical instrument based on which of the different calibration areas contacts the tip of the medical instrument.

[0039] Advantageously, the various calibration areas on the calibration device are preferably visual indicators on the calibration device so that two medical instruments can be automatically distinguished even when the two respective medical instruments have the same working length.

[0040] The calibration unit may be configured to calculate a centering error, and / or a positioning error, and / or an angular error, and to compensate for the centering error, and / or positioning error, and / or angular error calculated when calculating the distance between the calibration device and at least one of the two localizers.

[0041] The calibration device can be linked to a specific procedure by complementing the medical instrument identification mechanism's software with a specific procedure and / or surgical workflow, allowing automatic instrument identification through multiple steps of the procedure. When the calibration device is linked to a specific software workflow, the calibration device can calibrate the medical instrument, identify the medical instrument, and display a corresponding visualization and / or workflow.

[0042] By implementing certain methods in the software and / or linking the calibration device to the surgical workflow, two medical instruments having the same working length can be automatically distinguished. The algorithms in the software implementing the medical instrument identification can be configured to recognize medical instruments that may result from a calibration procedure and suggest a medical instrument to be used in the current step of the workflow.

[0043] Preferably, the algorithm is configured to visualize all identified medical instruments resulting from the calibration procedure and highlight for confirmation to the user the medical instruments that are proposed according to a predefined workflow, which the user can select but also select other medical instruments if the workflow was not followed.

[0044] Most preferably, the algorithm is configured to display suggested medical instruments and other possible equipment for selection by the user for a duration of, for example, 3, 5 or 10 seconds, but preferably also to display the remaining time (e.g., as a countdown). The algorithm may be configured to automatically select a suggested medical instrument if the user does not make any selection.

[0045] The calibration unit of the medical instrument identification mechanism is configured to calibrate the medical instrument using a sensor carrier disposed within its lumen. Calibrating the medical instrument using the sensor carrier includes calculating a distance between a tip of the medical instrument and at least one of the two localizers based on a position and orientation of the calibration device and a position and orientation of the at least one of the two localizers determined by the position detection system. For example, to calibrate the medical instrument using the sensor carrier disposed within the lumen of the medical instrument, the tip of the medical instrument can be brought into contact with the calibration device.

[0046] The calibration unit may be configured to automatically detect whether the tip of the medical instrument is in contact with the calibration device by determining whether a virtual longitudinal axis defined by the positions of the at least two localizers intersects with a known position of the calibration device for a predefined period of time and / or whether a distance between the calibration device and at least one of the localizers remains constant for a predefined period of time.

[0047] The calibration unit may be configured to initiate an automatic calibration of the medical instrument when it determines that the tip of the medical instrument is in contact with the calibration device, and in particular, when in contact, determine a distance between the calibration device and at least one of the two localizers, the distance corresponding to a distance between the tip of the medical instrument and a respective one of the at least two localizers.

[0048] The calibration allows a conversion function to be established by the calibration unit, the conversion function representing the spatial relationship between the tip of the medical instrument and the at least two localizers.

[0049] The medical instrument identification unit of the medical instrument identification mechanism is configured to determine a lumen length of the medical instrument from at least the calculated distance and to use the determined lumen length to identify the medical instrument. In particular, the medical instrument identification unit is connected to the calibration unit to obtain the calculated distance between the tip of the medical instrument and the at least two localizers.

[0050] The present invention encompasses the recognition that the length of a medical device's lumen is generally characteristic of the medical device itself. Thus, a medical device may be identified by the length of its lumen.

[0051] The present invention includes the further recognition that the length of the lumen of the medical instrument may be obtained automatically when calibrating the medical instrument with a sensor carrier disposed within the lumen of the medical instrument, and thus the length of the lumen of the medical instrument may be automatically determined by the sensor carrier and used to identify the medical instrument.

[0052] Automatically obtaining the lumen length of the medical instrument may be accomplished using a medical instrument identification mechanism in that a distance between the tip of the medical instrument and at least one of the two localizers is calculated by the calibration unit, and the calculated distance is used by the medical instrument identification unit to determine the lumen length of the medical instrument. The medical instrument identification unit is configured to automatically identify the medical instrument based on the determined lumen length.

[0053] As a result, the calibrated medical instrument on which the sensor carrier is placed can be automatically identified by the medical instrument identification unit of the medical instrument identification mechanism based on the length of the lumen of the medical instrument.

[0054] The information of the identified medical instrument may for example be used to adapt the way in which the medical instrument is displayed or visualized on a monitor, for example a digital representation of that medical instrument identified by the medical instrument identification unit (i.e. a representation of the medical instrument in a 2D or 3D view) for visualization on the monitor may be particularly accurate for the identified medical instrument.

[0055] The identified medical instrument information may also be used to automatically adapt the software workflow depending on how the identified medical instrument is used in the navigated procedure.

[0056] The identified medical instrument information can also be used to automatically adapt the monitor's view for the instrument being used. For example, if an endoscope is identified during a navigated procedure, the software can automatically switch to display a video view from the endoscope in parallel with the navigation view. The medical instrument identification can be linked to the workflow of a given software procedure, where the combination of medical instrument identification and software workflow can guide the surgeon through the navigated procedure.

[0057] The medical instruments that may be identified by the medical instrument identification mechanism generally include medical instruments having a lumen in which a sensor carrier may be placed to operatively connect the medical instrument to the position detection system. Such medical instruments that generally have a lumen are, for example, catheters, access needles, taps, screwdrivers, and bone screws (e.g., pedicle screws) that may be placed by a screwdriver.

[0058] Additional medical instruments that may include a sensor carrier are those that generally do not have a lumen but are retrofitted with a lumen or are originally manufactured with a lumen suitable for inserting the sensor carrier in. Such medical instruments may be scalpels, surgical saws (e.g., bone saws), bone rasps, cautery instruments, forceps, endplate rasps, cage trial devices, or cage placement devices.

[0059] The medical instrument may be identified based at least on a distance between at least one of the two localizers and the tip of the medical instrument, which may be determined based on the position and orientation of the calibration device and the position and orientation of the at least one of the two localizers. In addition to the calculated distance, the medical instrument may be identified based on a calculated angle of the medical instrument and / or a length of a section of the sensor carrier that is outside of the lumen of the medical instrument in which the sensor carrier is disposed (i.e., the portion of the sensor carrier that extends beyond the proximal end of the lumen of the medical instrument).

[0060] As an example, the length of the lumen of the medical instrument can be automatically determined based on a sensor carrier having a fixed length and a localizer of the sensor carrier positioned at a fixed relative position (e.g., within a hypotube). Preferably, the length of the sensor carrier is shorter than the length of the lumen of the medical instrument that can be automatically identified during a navigated procedure. For example, the sensor carrier can have a length corresponding to the length of the lumen of the medical instrument among a plurality of medical instruments that can be automatically identified during a navigated procedure having the shortest lumen length. Thus, when the sensor carrier is successively inserted into each of a plurality of medical instruments that can be automatically identified during a navigated procedure, for each medical instrument, the distance between its tip and the localizer of the positioned sensor carrier is different from the distance obtained for the other medical instruments among a plurality of medical instruments that can be automatically identified. For example, the distance between the tip of the medical instrument and at least one of the localizers of the sensor carrier can be calculated first, and the remaining length of the sensor carrier can be added to the calculated distance to obtain the lumen length of the medical instrument. For example, a length value of the sensor carrier can be provided prior to a medical instrument identification unit of the medical instrument identification mechanism, which can be configured to use the provided length of the sensor carrier to determine the length of the lumen of the medical instrument. In particular, if the position of a localizer of the sensor carrier relative to the distal and / or proximal ends of the sensor carrier is known, the distance from the localizer to the distal and / or proximal ends of the sensor carrier, respectively, can be used to determine the length of the lumen of the medical instrument housing the sensor carrier.

[0061] When the sensor carrier is disposed within the lumen of the medical instrument, the distance between the localizer of the sensor carrier and the tip of the medical instrument is characteristic of the length of the lumen of the medical instrument, and therefore the length of the lumen itself can be derived from the calculated distance between the localizer and the tip of the medical instrument.

[0062] The sensor carrier of the medical instrument identification mechanism may be provided with a pre-calibrated longitudinal axis in the coordinate system of the position detection system, and a calibration matrix representing the spatial relationship may be used to calibrate and navigate the medical instrument having the sensor carrier disposed within its lumen.

[0063] In particular, when the lumen of the medical instrument is straight, the longitudinal axis of the sensor carrier coincides with the physical axis of the medical instrument. A calibration matrix of a pre-calibrated medical instrument may be advantageously used by the position detection system and / or the calibration unit to calculate the virtual longitudinal axis of the medical instrument and to extrapolate the distal end of the medical instrument.

[0064] It is advantageous if the sensor carrier itself is rigid, at least in the section where the localizer is located, so that the precalibrated state remains valid even outside the straight lumen of the medical instrument.

[0065] The medical implement identification mechanism according to the present invention may be used with a surgical kit as part of a medical system, the surgical kit including a plurality of medical implements having lumens in which at least a portion of a sensor carrier may be disposed. The medical implement identification mechanism according to the present invention is particularly suited for identifying medical implements in the surgical kit, each having a length that is different from the length of the lumens of other medical implements in the surgical kit.

[0066] Preferably, to identify a medical instrument of a surgical kit, a sensor carrier having a length equal to or less than the length of the lumen of the medical instrument of the surgical kit with the shortest lumen may be used. In this case, the sensor carrier may be placed in each lumen of the medical instrument over its entire length. For each medical instrument of the surgical kit, the distance between the tip of the respective medical instrument and the localizer of the sensor carrier is unique and may be used to distinguish the surgical kit from other surgical kits. Thus, the distance calculated for one of the medical instruments may be used to identify the medical instrument.

[0067] To identify the medical instruments of the surgical kit, a sensor carrier with a lumen longer than at least two of the medical instruments of the surgical kit can also be used. In this case, the medical instruments can be identified, for example, by the distance between the tip of the medical instrument and at least one of the two localizers, and preferably by at least one of the angle of the medical instrument or the length of that section of the sensor carrier that extends beyond the proximal end of the medical instrument. In order to use the length of that section of the sensor carrier that extends beyond the proximal end of the medical instrument to identify the medical instrument, the position and orientation of the proximal end of the medical instrument and the proximal end of the sensor carrier generally need to be determined, for example using a position detection system. For this purpose, the sensor carrier can have a localizer (distal localizer) arranged at the distal end of the sensor carrier and another localizer (proximal localizer) arranged at a distance from the distal localizer towards the proximal end of the sensor carrier. The position of the proximal localizer may be indicated, for example, by a color marking, and to calibrate the medical instrument, the sensor carrier may be placed within the lumen of the medical instrument such that the color marking is located at the proximal end of the medical instrument, where the distance between the proximal localizer and the color marking corresponds to the length of a section of the sensor carrier that extends beyond the proximal end of the medical instrument that may be used to identify the medical instrument.

[0068] With respect to a surgical kit, it is an advantage of the medical implement identification feature that it facilitates quick and easy switching between the medical implements of the kit. Furthermore, in a surgical kit, the medical implements of the kit can be designed to be easily identified and therefore reliably recognized.

[0069] The calibration unit and the medical instrument identification unit may be components of a data processing device, such as a computer, and may be implemented, for example, by a processor, volatile and non-volatile computer memory, and software.

[0070] The medical instrument identification unit may be configured to identify the medical instrument in which the sensor carrier is located by comparing the determined length of the lumen of the medical instrument with a plurality of medical instruments having various lengths contained in a database, preferably the database including at least the lumen lengths of those medical instruments that may be used during the navigated procedure.

[0071] In some embodiments of the medical instrument identification mechanism, the at least two localizers are positioned near a distal end of the sensor carrier at a distance from each other. The sensor carrier may include at least a third localizer configured to provide a sensor signal representative of the position and orientation of the third localizer. Preferably, the third localizer is positioned at a distance from the first and second localizers toward the proximal end of the sensor carrier. Preferably, the third localizer is positioned near the proximal end of the sensor carrier. A sensor carrier with a third localizer positioned near the proximal end of the sensor carrier is particularly suitable for determining the angle of the medical instrument. The angle (corner) of the medical instrument, like the length of the lumen of the medical instrument, may be used to identify the medical instrument. For example, a sensor carrier with a third localizer may be positioned in the lumen of the medical instrument such that the corner of the medical instrument is located between the at least two localizers and the third localizer. From the determined positions and orientations of the third localizer and at least one of the at least two localizers, respectively, an angle of the medical instrument is calculated, which angle can be used by the medical instrument identification unit for identifying the medical instrument in which the sensor carrier is arranged. Advantageously, the position and orientation of the at least one of the localizers arranged in the distal end region of the medical instrument and the position and orientation of the third localizer can also be used for determining the rotational orientation of the sensor carrier about the longitudinal axis of the medical instrument, i.e. the physical axis of the medical instrument.

[0072] According to the invention, a method for automatically identifying a medical instrument is proposed, the method comprising the steps of: - providing a sensor carrier configured to be removably disposed within a lumen of a medical instrument, the sensor carrier having at least two localizers, each localizer configured to provide a sensor signal indicative of a position and an orientation of the respective localizer; - providing a calibration device whose position and orientation in the coordinate system of the position detection system is known; - inserting a sensor carrier into a lumen of a medical instrument; - determining the position and orientation of at least two localizers from the provided sensor signals; - calculating a distance between a calibration device and at least one of the two localizers based on the determined positions and orientations of the at least two localizers in order to calibrate the medical instrument; - determining a length of the lumen of the medical device from at least the calculated distance; - using the determined length of at least the lumen to identify the medical device.

[0073] The method of the present disclosure may be carried out in conjunction with a medical implement identification mechanism according to the present invention as described above.

[0074] Preferably, after insertion, the sensor carrier is positioned within the lumen of the medical instrument and the at least two localizers are spaced apart from each other along a longitudinal axis of the medical instrument.

[0075] In some variations of the method for automatically identifying a medical instrument, the method includes contacting a calibration device with a tip of the medical instrument.

[0076] It is particularly preferred that the distance between the calibration device and at least one of the two localizers is calculated based on the position and orientation of at least one of the two localizers determined when the tip of the medical instrument is in contact with the calibration device.

[0077] Similarly, if the calibration device is equipped with at least one localizer, the position and orientation of the localizer of the calibration device can also be determined in the coordinate system of the position detection system using the position detection system. In particular, the position and orientation of the localizer of the calibration device can be determined by the position detection system and used by the calibration unit to calculate the distance between the calibration device and at least one of the two localizers, for example when the tip of the medical instrument is in contact with the calibration device.

[0078] The medical instrument may be a medical screwdriver with a medical screw (e.g., a bone screw) attached to a distal end of the screwdriver. The lumen of the medical screwdriver in which the sensor carrier is located preferably extends from a proximal end of the screwdriver to a distal end of the attached screw. In particular, when the medical instrument is a medical screwdriver with a medical screw, the method for automatically identifying the medical instrument may include a step of determining a length of the medical screw.

[0079] The step of determining the length of the medical screw preferably comprises: - contacting the calibration device with the tip of the medical screw and determining the position and orientation of at least two localizers during contact; - calculating a distance between the calibration device and at least one of the two localizers based on the determined position and orientation; - determining a length of the screw from at least the calculated distance and using at least the determined length to identify the medical screw.

[0080] Additionally or alternatively, the method for automatically identifying a medical instrument according to the present invention may comprise a rotation step of rotating the sensor carrier around its longitudinal axis by at least 180 degrees, preferably 360 degrees, and simultaneously with the rotation step, a step of determining a position and orientation relative to at least the localizer and using the determined position and orientation to calculate a centering error, and / or a positioning error, and / or an angular error.

[0081] In particular, in a variant of the method for automatically identifying a medical instrument for which a centering error, and / or a positioning error, and / or an angular error is calculated, preferably the method may further comprise a step of compensating for the calculated centering error, and / or positioning error, and / or angular error when calculating the distance between the calibration device and at least one of the two localizers.

[0082] In particular, when the sensor carrier includes at least a third localizer configured to provide a sensor signal representative of a position and an orientation of the third localizer, the third localizer being positioned at a distance from the first and second localizers towards a proximal end of the sensor carrier, the method for automatically identifying a medical instrument according to the invention comprises: - determining the position and orientation of a third localizer; - calculating an angle of the medical instrument from the position and orientation of the third localizer and from the position and orientation of at least one of the first and second localizers; - using the calculated angle to identify the medical instrument.

[0083] Preferably, the lumen of the medical instrument in which the sensor carrier is located is an eccentric lumen, whereby the medical instrument can include further lumens that can be used for various purposes even when the sensor carrier is located in an eccentric lumen. [Brief description of the drawings]

[0084] In the following, preferred embodiments of the present invention will be described with reference to the drawings.

[0085] [Figure 1] FIG. 2 shows a schematic representation of a sensor carrier for connecting a medical instrument to a position detection system. [Diagram 2] FIG. 2 shows a schematic diagram of a medical implement identification mechanism including a sensor carrier and a calibration device. [Diagram 3] FIG. 2 shows a schematic diagram of a medical instrument with a sensor carrier, the medical instrument being in contact with a calibration device; [Figure 4] FIG. 4 illustrates the geometric arrangement of the localizer, medical instrument and calibration device of the sensor carrier as shown generally in FIG. 3. [Diagram 5] A schematic diagram showing a screwdriver with a pedicle screw attached and a sensor carrier positioned within the lumen of the screwdriver and the pedicle screw, with the pedicle screw in contact with a calibration device. [Figure 6] FIG. 6 illustrates the geometric arrangement of the localizer, screwdriver, and calibration device of the sensor carrier as shown diagrammatically in FIG. 5. [Figure 7] 1 is a flow chart illustrating a method for automatically identifying a medical instrument. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0086] FIG. 1 shows a schematic of a sensor carrier 100 for connecting a medical instrument to a position detection system. The sensor carrier 100 can be inserted into the lumen of the medical instrument to connect the medical instrument to the position detection system. With the sensor carrier 100 disposed within the lumen of the medical instrument, a navigated procedure can be performed, e.g., the location of the medical instrument within the patient's body can be displayed on a monitor. After completing the navigated procedure, the sensor carrier can be removed from the lumen of the medical instrument and inserted into the lumen of another medical instrument to connect the other medical instrument to the position detection system.

[0087] The sensor carrier 100 has a distal end 102 and a proximal end 104. The sensor carrier 100 includes three localizers 106, 108, 110 distributed along the length of the sensor carrier 100. Each of the localizers 106, 108, 110 is configured to provide a sensor signal representative of the position and orientation of each localizer 106, 108, 110. For example, each of the localizers 106, 108, 110 may include at least one sensor coil for connecting a medical instrument on which the sensor carrier 100 is disposed to an electromagnetic position detection system.

[0088] A first of the three localizers 106 is located near the distal end 102 of the sensor carrier. A second of the three localizers 108 is located a distance away from the first localizer 106 toward the proximal end 104 of the sensor carrier 100. The sensor carrier 100 further includes a third localizer 110 located a distance away from the first localizer 106 and the second localizer 108 toward the proximal end 104 of the sensor carrier. The third of the three localizers 110 is optional and is not present in alternative embodiments of the sensor carrier 100.

[0089] The sensor carrier 100 with three localizers 10, 108, 110 is particularly suitable for identifying medical instruments having a characteristic angle (corner) relative to the medical instrument. Preferably, in order to calculate the angle of the medical instrument, the sensor carrier 100 is placed in the lumen of the medical instrument such that the corner of the medical instrument is located between the third localizer 110 and the first localizer 106 and the second localizer 108. From the determined positions and orientations of the localizers 106, 108, 110, the angle of the medical instrument can be calculated, for example with the aid of a calibration unit of the medical instrument identification mechanism, and used by the medical instrument identification unit of the medical instrument identification mechanism to identify the medical instrument in whose lumen the sensor carrier 100 is placed.

[0090] The sensor carrier 100 further includes a hypotube 112 that extends from the distal end 102 to the proximal end 104 of the sensor carrier 100 and surrounds the three localizers 106, 108, 110. The hypotube 112 is configured to provide mechanical stability to the sensor carrier 100 and protect the localizers 106, 108, 110 from external influences.

[0091] FIG. 2 shows a schematic diagram of a medical implement identification mechanism 200 including a sensor carrier 202 , a calibration device 204 , a position detection system 206 , a calibration unit 208 , and a medical implement identification unit 210 .

[0092] The sensor carrier 202 may be configured similarly to the sensor carrier described with reference to FIG. 1. In particular, the sensor carrier 202 may have at least two localizers (not shown), and optionally at least a third localizer, preferably disposed near the proximal end of the sensor carrier. Each of the localizers is configured to provide a sensor signal representative of the position and orientation of the respective localizer. The sensor carrier 202 is configured to be removably disposed within the lumen of the medical instrument for connecting the medical instrument to the position detection system 206.

[0093] The sensor carrier 202 is connected to a location detection system 206 via a cable 203. In some embodiments of the medical instrument identification mechanism 200, a sensor carrier is provided that may be wirelessly connected to the location detection system 206. Sensor signals provided by a localizer of the sensor carrier 202 may be transmitted to the location detection system 206 via the cable 203. The location detection system 206 is configured to determine a position and orientation of the localizer of the sensor carrier 202 in a coordinate system 212 of the location detection system from the received sensor signals.

[0094] For example, the position detection system 206 may be an electrometric position detection system having a field generator for generating an alternating electromagnetic field. To determine the position and orientation of the localizer of the sensor carrier, the localizer preferably includes one or more sensor coils. When exposed to the alternating electromagnetic field, a voltage is induced in each coil depending on the position and orientation of the sensor coil within the alternating electromagnetic field. A sensor signal representing the induced voltage is tapped from each sensor coil and transmitted to the position detection system to determine the position and orientation of the sensor coil, respectively.

[0095] The calibration device 204 of the medical instrument identification mechanism 200 is configured such that its position and orientation in the coordinate system 212 of the position detection system can be determined by the position detection system 206. For example, the calibration device 204 can be placed at a location whose coordinates in the coordinate system 212 of the position detection system are known. The calibration device 204 can also include one or more localizers such that the position and orientation of the calibration device 204 can be determined directly by the position detection system 206. The calibration device 204 is preferably connected to the position detection system 206.

[0096] The position detection system 206 is connected to a calibration unit 208. The calibration unit 208 is configured to calibrate the medical instrument with the sensor carrier 202 arranged in its lumen by calculating the distance between the tip of the medical instrument and at least one of the localizers of the sensor carrier. The calibration unit 208 is configured to use the position and orientation of the calibration device 204, which is known in the coordinate system 212 of the position detection system, and the position and orientation of at least one of the localizers of the sensor carrier determined by the position detection system 206. Preferably, the calibration unit is configured to determine whether the tip of the medical instrument is in contact with the calibration device 204 and the position and orientation of at least one of the localizers of the sensor carrier determined by the position detection system 206 at the moment of contact between the tip of the medical instrument and the calibration device 204.

[0097] Since the distance between the tip of the medical instrument and at least one of the localizers of the sensor carrier is characteristic of the length of the lumen of the medical instrument, the length of the lumen can be derived from the calculated distance. Furthermore, since the length of the lumen of the medical instrument is characteristic of the medical instrument itself, the determined length of the lumen of the medical instrument can be used to automatically identify the medical instrument in whose lumen the sensor carrier 202 is disposed.

[0098] To identify the medical instrument in whose lumen the sensor carrier 202 is disposed, the medical instrument identification mechanism 200 includes a medical instrument identification unit 210 connected to the calibration unit 208 for obtaining a calculated distance between the tip of the medical instrument and at least one of the localizers of the sensor carrier. The medical instrument identification unit 210 is configured to determine a length of the lumen of the medical instrument from at least the distance between the tip of the medical instrument and at least one of the localizers of the sensor carrier calculated by the calibration unit 208. The medical instrument identification unit 210 is configured to use the determined length of the lumen of the medical instrument to identify the medical instrument. Alternatively or additionally to the length of the lumen, the medical instrument identification unit 210 may be configured to use an angle of the medical instrument calculated by the calibration unit 208 from the position and orientation of at least two localizers between which a corner of the medical instrument is located when the sensor carrier is disposed in the lumen of the medical instrument. To identify the medical instrument, the medical instrument identification unit 210 may be configured to compare the distance, and optionally the angle of the medical instrument, calculated by the calibration unit 208 with various lengths (and angles) of a plurality of medical instruments contained in a database accessible by or that is part of the medical instrument identification unit 210.

[0099] 3 shows a schematic of a medical instrument 300 with a sensor carrier 302. A tip 304 of the medical instrument is in contact with a calibration device 306. The medical instrument 300 has a lumen 308 extending from the proximal end of the medical instrument to its distal end. The sensor carrier 302 is disposed within the lumen 308. The sensor carrier 302 includes two localizers 310, 312, a first of the two localizers 310 being disposed at a distal end 314 of the sensor carrier 302 and a second of the two localizers 312 being disposed at a distance from the first localizer 310 towards a proximal end 316 of the sensor carrier.

[0100] The use of two localizers arranged in the distal end region of the sensor carrier is particularly advantageous in that it facilitates the determination of the authenticity of the virtual longitudinal axis of the medical instrument relative to the physical longitudinal axis of the medical instrument. By extrapolating the virtual longitudinal axis from the distal end of the sensor carrier to the distal end of the medical instrument, the position of the distal end of the medical instrument can be determined. The virtual longitudinal axis of the medical instrument can also be displayed on the cross-sectional image on the monitor. Displaying the virtual longitudinal axis on the cross-sectional image on the monitor can be particularly important when aiming, for example, with a medical instrument at an anatomical target from a long distance (e.g., 5-15 cm). Using the accurately displayed virtual longitudinal axis of an access needle or the like, the surgeon can evaluate the position and orientation of the needle and reliably navigate the needle to the target position.

[0101] It is also possible to determine the virtual longitudinal axis with a single localizer implementing only a 5DOF sensor. However, using a single 5DOF sensor to determine the virtual longitudinal axis of a medical instrument is typically subject to coil angle errors, errors caused by physical alignment within the sensor carrier, and errors caused by physical alignment of the sensor carrier inside the instrument. This can result in an angular error of 4° to 5°.

[0102] Advantageously, using two localizers, each implementing a 5DOF sensor, for example by using sensor coils, the angular error can be reduced to just the positioning error of both sensor coils. With a spacing of the sensor coils 100mm apart relative to each other and a positioning error of less than 1mm, the angular error can be reduced to less than tan1° (tan(1 / 100)).

[0103] Because the length of the sensor carrier 302 is less than the length of the medical instrument 300, there is a non-zero distance between the sensor carrier distal end 314 and the medical instrument tip 304. The distance is characteristic of the medical instrument and can be used to determine the length of the medical instrument lumen 308. Since the length of the medical instrument lumen 308 is characteristic of the medical instrument 300 itself, the length of the medical instrument lumen 308 can identify the medical instrument 300 in which the sensor carrier 302 is located.

[0104] The medical instrument 300 can be, for example, a medical instrument provided with a lumen 308 for forward advancement of the medical instrument 300 over a guidewire. For example, the medical instrument 300 can be an access needle, a guide rod, a working tube, a tap, a balloon dilator, or a screwdriver.

[0105] The sensor carrier 302 may be configured similarly to the sensor carrier described with reference to Figure 1 or similarly to the sensor carrier described with reference to Figure 2. In particular, the sensor carrier 302 and the calibration device 306 may be elements of a medical implement identification mechanism, such as the medical implement identification mechanism described with reference to Figure 2.

[0106] FIG. 4 shows the geometric arrangement of the sensor carrier localizers 310, 312, the medical instrument, and the calibration device 306 as described with reference to FIG.

[0107] The two localizers 310 , 312 are positioned at a distance from each other along the longitudinal axis 400 of the medical instrument 300 .

[0108] In order to automatically identify the medical instrument 300, a distance 402 between the calibration device 306 and a localizer 310 arranged near the distal end of the sensor carrier is calculated, for example by a calibration unit as described with reference to Figure 2. To calculate the distance 402, preferably the position and orientation of the calibration device 306 of the medical instrument identification mechanism and the position and orientation of the localizer 310 determined by a position detection system, for example, may be used.

[0109] In particular, the position and orientation of the localizer 310 may be determined when the tip of the medical instrument is in contact with the calibration device 306 and used to calculate the distance 402. Advantageously, when the tip of the medical instrument is in contact with the calibration device 306, the position of the tip of the medical instrument can be directly related to the position and orientation of the calibration device 306.

[0110] The position and orientation of the second localizer 312 may be used as a reference to perform a validity check of the calculated distance 402. The positions and orientations of the first localizer 310 and the second localizer 312 may also be used to calculate a centering error, and / or a positioning error, and / or an angular error. The calculated centering error, and / or a positioning error, and / or an angular error may be compensated for when calculating the distance 402 between the calibration device and the localizer 310. This allows the distance 402 between the calibration device 306 and the localizer to be calculated with improved accuracy.

[0111] Once the distance 402 between the calibration device 306 and the localizer 310 is calculated, the distance 402 may be used to determine the length of the medical instrument lumen 308 based on which the medical instrument 300 itself can be identified.

[0112] Like FIG. 3, FIG. 5 shows a schematic representation of a medical device with a sensor carrier disposed thereon, the medical device being in contact with a calibration device.

[0113] In FIG. 5, the medical instrument is a screwdriver 500 having a medical screw 502 (eg, a bone screw, preferably a pedicle screw) attached thereto.

[0114] The lumen 504 extends from a proximal end 506 of the screwdriver to a distal end 508 of the medical screw. A sensor carrier 510 is disposed in the lumen 504. The sensor carrier 510 includes two localizers 512, 514, a first localizer 512 disposed near a distal end 516 of the sensor carrier and a second localizer disposed at a distance from the first localizer 512 toward a proximal end 518 of the sensor carrier. The sensor carrier 510 may be configured similarly to the sensor carrier described with reference to FIG. 1 or with reference to FIG. 2.

[0115] The medical screw 502 has a length 520 that is characteristic of the medical screw 502. Therefore, by determining the length of the screw, the medical screw 502 itself can be identified by the length of the screw.

[0116] At its proximal end 506, the medical screw 502 is in contact with a calibration device 522 for calibrating the screwdriver 500, such as by a calibration unit of a medical instrument identification mechanism, as described with reference to Fig. 2. Calibrating the screwdriver includes determining a distance 600 between the calibration device 522 and a first localizer 512, as shown in Fig. 6.

[0117] Figure 6 shows the geometric arrangement of the localizers 512, 514, screwdriver, and calibration device 522 of the sensor carrier as shown generally in Figure 5. The localizers 512, 514 are arranged along the longitudinal axis 602 of the screwdriver. In particular, the position and orientation of the first localizer 512 is used to calculate a distance 600 to the calibration device that corresponds to the distance between the first localizer 512 and the proximal end 506 of the medical screw.

[0118] The distance 600 is characteristic for the length of the medical screw 502. Thus, the determined distance 600 can be used to automatically identify the medical screw 502. For example, the length of the screwdriver 500 and the length of the sensor carrier 510 can be used to identify the medical screw 502 based on the determined distance 600. The fact that the relative positions of the localizers with respect to each other are fixed can also be utilized. Preferably, the first localizer 512 is located near the distal end of the sensor carrier such that the position and orientation of the distal end of the sensor carrier can be obtained by determining the position and orientation of the first localizer.

[0119] The calibration device 522 and the sensor carrier 510 may be elements of a medical implement identification mechanism, in particular the medical implement identification mechanism described with reference to FIG.

[0120] FIG. 7 is a flow chart illustrating a method for automatically identifying a medical instrument.

[0121] First, in step S1, a sensor carrier is provided. The sensor carrier is configured to be removably disposed in a lumen of a medical instrument. The sensor carrier has at least two localizers. Each of the localizers is configured to provide a sensor signal representative of a position and an orientation of each localizer. The sensor carrier may be the sensor carrier described with reference to FIG. 1 or FIG. 2, or the sensor carrier described with reference to FIG. 3 or FIG. 5.

[0122] In step S2, a calibration device is provided. The position and orientation of the calibration device in the coordinate system of the position detection system is known. For example, the calibration device may be located at a position whose coordinates in the coordinate system of the position detection system are known. The calibration device may also include one or more localizers configured to provide sensor signals indicative of the position and orientation of the calibration device.

[0123] The sensor carrier is inserted into the lumen of the medical instrument (step S3). The medical instrument having a lumen can be, for example, a catheter, a Jamshidi needle, a tap, a screwdriver with a bone screw, such as a pedicle screw that can be placed in the patient's bone by the screwdriver, or another medical instrument provided with a cannula. After insertion, the sensor carrier is removably disposed in the lumen of the medical instrument, so that the sensor carrier can be removed after completing the task with the medical instrument and used to connect another medical instrument to the position detection system.

[0124] From the sensor signals provided in step S4, the positions and orientations of the at least two localizers are determined. For example, the localizers may include one or more sensor coils, the positions of which may be determined by an electromagnetic position detection system having a field generator for generating an alternating electromagnetic field. When exposed to the generated electromagnetic field, a voltage representative of the position and orientation of the sensor coils is induced. From the tapped sensor signals representative of the induced voltages, the position and orientation of the sensor coils in the coordinate system of the position detection system may be determined by the position detection system.

[0125] In step S5, a distance between the calibration device and at least one of the two localizers is calculated based on the position and orientation of the localizer determined for calibrating the medical instrument. Preferably, the distance is calculated based on the position and orientation of the localizer determined when the tip of the medical instrument is in contact with the calibration device.

[0126] Then, in step S6, the length of the lumen of the medical instrument is determined from at least the calculated distances. In particular, the distance between the calibration device and at least one of the two localizers is characteristic for the length of the lumen of the medical instrument and thus the medical instrument itself.

[0127] Then, in step S7, at least the determined lumen length is used to automatically identify the medical instrument within whose lumen the sensor carrier is disposed. Additionally, the angle of the medical instrument and / or the length of that section of the sensor carrier that extends beyond the proximal end of the medical instrument may also be used to identify the medical instrument. To identify the medical instrument, the determined lumen length may be compared to entries in a database representing the lumen lengths of various medical instruments (e.g., medical instruments in a surgical kit used during a surgical procedure).

[0128] If the medical instrument is automatically identified, for example by a medical instrument identification mechanism, the mode of displaying the medical instrument on the monitor can be adapted accordingly.

[0129] The method may be implemented in conjunction with a medical implement identification mechanism, in particular the medical implement identification mechanism described with reference to FIG.

Claims

1. A medical device identification mechanism comprising: a sensor carrier configured to be removably positioned within a lumen of a medical instrument, the sensor carrier having at least two localizers, each localizer configured to provide a sensor signal indicative of a position and an orientation of the respective localizer; a position detection system configured to determine positions and orientations of at least two of the localizers in a coordinate system of the position detection system from the received sensor signals; a calibration device configured to enable the position detection system to determine a position and orientation of the position detection system in the coordinate system; a calibration unit configured to calibrate the medical instrument with the sensor carrier disposed within the lumen by calculating a distance between a tip of the medical instrument and at least one of the two localizers based on the position and orientation of the calibration device and the position and orientation of at least one of the two localizers determined by the position detection system when the tip of the medical instrument is in contact with the calibration device; and a medical instrument identification unit configured to determine a length of the lumen of the medical instrument from at least the calculated distance and use the determined length of the lumen to identify the medical instrument.

2. the sensor carrier having a distal end and a proximal end; 2. The medical instrument identification mechanism of claim 1, wherein a first of the at least two localizers is positioned at or at least near the distal end of the sensor carrier and a second of the at least two localizers is positioned a distance from the first localizer toward the proximal end of the sensor carrier.

3. and further comprising at least a third localizer; 3. The medical instrument identification mechanism of claim 1, wherein the third localizer is configured to provide a sensor signal representative of a position and orientation of the third localizer and is positioned a distance from the at least two localizers toward a proximal end of the sensor carrier.

4. The medical instrument identification mechanism according to any one of claims 1 to 3, wherein the calibration unit is configured to determine a virtual longitudinal axis of the medical instrument based on the positions of at least two of the localizers.

5. The medical instrument identification mechanism of any one of claims 1 to 4, wherein the calibration unit is configured to extrapolate a virtual longitudinal axis of the medical instrument from a distal end of the positioned sensor carrier and determine the position of the distal end of the medical instrument in order to calibrate the medical instrument.

6. The medical instrument identification mechanism of any one of claims 1 to 5, wherein the calibration unit is configured to automatically detect whether the tip of the medical instrument is in contact with the calibration device by determining whether a virtual longitudinal axis defined by the positions of at least two of the localizers intersects with a known position of the calibration device for a predefined period of time, and to initiate automatic calibration of the medical instrument when it is detected that the tip of the medical instrument is in contact with the calibration device.

7. The medical instrument identification mechanism of any one of claims 1 to 6, wherein the medical instrument identification unit includes a database containing different medical instruments having a plurality of lengths, and is configured to identify the medical instrument in which the sensor carrier is positioned by comparing the determined length of the lumen of the medical instrument with the plurality of lengths of the different medical instruments contained in the database.

8. The medical instrument identification mechanism of any one of claims 1 to 7, wherein the medical instrument identification unit is configured to identify the medical instrument based on a calculated angle of the medical instrument and / or based on a length of a portion of the sensor carrier that is located outside the lumen of the medical instrument in which the sensor carrier is located.

9. A medical system comprising the medical instrument identification mechanism according to any one of claims 1 to 8 and a surgical kit, The medical system, wherein the surgical kit includes a plurality of medical instruments having a lumen in which at least a portion of the sensor carrier can be positioned.

10. 1. A method for automatically identifying a medical device, comprising: providing a sensor carrier configured to be removably disposed within a lumen of the medical instrument, the sensor carrier having at least two localizers, each localizer configured to provide a sensor signal indicative of a position and an orientation of a respective localizer; providing a calibration device whose position and orientation in a coordinate system of the position detection system is known; inserting the sensor carrier into the lumen of the medical instrument; determining a position and orientation of at least two of the localizers from the provided sensor signals, the step of contacting the calibration device with a tip of the medical instrument and determining the position and orientation of the at least two localizers while in contact; calculating a distance between the calibration device and at least one of the two localizers based on the determined position and orientation to calibrate the medical instrument; determining a length of the lumen of the medical device from at least the calculated distance; and using the determined length of at least the lumen to identify the medical device.

11. the medical instrument is a medical screwdriver having a medical screw attached to a distal end of the screwdriver; a lumen of the medical screwdriver in which a sensor carrier is disposed extending from a proximal end of the screwdriver to the distal end of the attached medical screw, contacting the calibration device with a tip of the medical screw and determining a position and orientation of at least two localizers while in contact; and calculating a distance between the calibration device and at least one of the two localizers based on the determined position and orientation, respectively.

11. The method of claim 10, further comprising: determining a length of the medical screw from at least the calculated distance; and using at least the determined length to identify the medical screw.

12. rotating the sensor carrier at least 180 degrees about its longitudinal axis; Concurrently with said rotating step, determining a position and orientation relative to at least said localizer; The method according to claim 10 or 11, further comprising the step of: using the determined position and orientation for calculating a centering error and / or a positioning error and / or an angular error.

13. 13. The method of claim 12, further comprising the step of compensating for the calculated centering error, and / or the positioning error, and / or the angular error when calculating the distance between the calibration device and at least one of the two localizers.

14. the sensor carrier has at least a third localizer configured to provide a sensor signal representative of a position and orientation of the third localizer and spaced a distance from at least two of the localizers toward a proximal end of the sensor carrier; determining positions and orientations of at least three of said localizers; calculating an angle of the medical instrument from the position and orientation of the third localizer and a position and orientation of at least one of a first localizer and a second localizer; The method of any one of claims 10 to 13, further comprising the step of: using the calculated angle to identify the medical instrument.

15. The method according to any one of claims 10 to 14, further comprising the step of automatically adapting, upon identification of the medical instrument, a mechanism for displaying a digital representation of the medical instrument on a monitor of the identified medical instrument.

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