An ear, nose and throat (ENT) navigable shaver with ferromagnetic components

Abstract

The system includes a medical probe and a position tracking system. The medical probe includes a distal tip and one or more distal magnetic position sensors. The medical probe further includes a proximal tip assembly and one or more proximal magnetic position sensors. The position tracking system includes a memory configured to retain values ​​indicative of a known relative position between the distal magnetic position sensor and the proximal magnetic position sensor. The position tracking system includes a processor configured to receive one or more signals indicative of estimated positions of the proximal and distal magnetic position sensors as measured by the position tracking system, and to initiate a corresponding action in response to detecting a discrepancy between the known relative positions and the estimated positions.

Description

[Technical field]

[0001] The present invention relates generally to invasive medical probes, and more particularly to methods and systems for tracking a medical probe within a patient's body. [Background technology]

[0002] Techniques for tracking a medical probe inside a cavity of a patient's organ have been previously proposed in the patent literature. For example, US Patent Application Publication No. 2018 / 0280049 describes a medical device including a disposable Ear-Nose-Throat (ENT) tool, a reusable handle, and a processor. The ENT tool is configured to perform a medical procedure within the patient's ENT organ. The reusable handle includes a position sensor configured to hold and control the disposable ENT tool and to generate one or more position signals indicative of a first position of the reusable handle. The processor is configured to receive the position signal from the position sensor and estimate a second position of the disposable ENT tool within the patient's ENT organ based on the position signal.

[0003] As another example, U.S. Patent No. 6,272,371 describes an invasive probe apparatus including a flexible elongate probe having a distal portion adjacent a distal end of the flexible elongate probe for insertion into a subject's body. The distal portion assumes a predetermined curved configuration when a force is applied thereto. First and second sensors are fixed to the distal portion of the probe at known locations relative to the distal end, and the sensors generate signals responsive to bending of the probe. Signal processing circuitry receives and processes the signals responsive to bending to find position and orientation coordinates of at least the first sensor and to determine locations of a plurality of points along the length of the distal portion of the probe. Summary of the Invention [Means for solving the problem]

[0004] One embodiment of the present invention provides a system including a medical probe and a position tracking system. The medical probe includes a distal end and one or more distal magnetic position sensors coupled to the distal end. The medical probe further includes a proximal end assembly and one or more proximal magnetic position sensors coupled to the proximal end assembly. The position tracking system includes a memory configured to hold values ​​indicative of a known relative position between the distal magnetic position sensor and the proximal magnetic position sensor. The position tracking system includes a processor configured to receive one or more signals indicative of an estimated position of the proximal magnetic position sensor and the distal magnetic position sensor as measured by the position tracking system, and to initiate a corresponding action in response to detecting a discrepancy between the known relative position and the estimated position.

[0005] In some embodiments, the distal end includes a portion that creates a change in a magnetic field across the distal end, hi some embodiments, the portion that creates a change in the magnetic field includes a ferromagnetic material.

[0006] In some embodiments, the distal position sensor is coupled to a shaft of the medical probe and the proximal magnetic position sensor is coupled to a handle of the medical probe.

[0007] In one embodiment, the shaft is rotating and the processor is configured to detect the mismatch based on values ​​generated by the rotating one or more distal magnetic position sensors.

[0008] In another embodiment, the processor is configured to correct the detected discrepancy based on values ​​indicative of the known relative positions.

[0009] In some embodiments, the processor is configured to alert a user to the detected inconsistency.

[0010] In some embodiments, the processor is configured to compare values ​​indicative of known relative positions with values ​​of the estimated position to detect discrepancies.

[0011] In one embodiment, the medical probe includes an ear, nose and throat (ENT) tool.

[0012] According to an embodiment of the present invention, there is additionally provided a method including inserting a medical probe into an organ of a patient, the medical probe including (a) a distal end, (b) one or more distal magnetic position sensors coupled to the distal end, (c) a proximal end assembly, and (d) one or more proximal magnetic position sensors coupled to the proximal end assembly, the distal end being tracked using a position tracking system by (i) maintaining a value indicative of a known relative position between the distal magnetic position sensor and the proximal magnetic position sensor, (ii) receiving one or more signals indicative of an estimated position of the proximal magnetic position sensor and the distal magnetic position sensor as measured by the position tracking system, and (iii) in response to detecting a discrepancy between the known relative position and the estimated position, initiating a corresponding action.

[0013] According to one embodiment of the present invention, there is further provided a medical probe including a distal tip, one or more distal magnetic position sensors, a proximal tip assembly, and one or more proximal magnetic position sensors, the one or more distal magnetic position sensors coupled to the distal tip, and the one or more proximal magnetic position sensors coupled to the proximal tip assembly.

[0014] The invention will be more fully understood from consideration of the following detailed description taken in conjunction with the drawings, in which: [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic, pictorial illustration of an ear, nose and throat (ENT) procedure using an ENT module with a navigable shaver, according to one embodiment of the present invention; FIG. [Diagram 2] 2 is a schematic, pictorial view of an ENT module applied in the ENT procedure of FIG. 1 according to one embodiment of the present invention. [Diagram 3]3 is a flow chart that generally illustrates a method and algorithm for tracking a distal end of the ENT module of FIG. 2 within a patient's head, in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Overview Some medical procedures require navigating the distal end of a medical probe inside a cavity of a patient's organ. For example, an ear, nose and throat (ENT) procedure may require navigating an ENT navigable shaver inserted into the sinuses of the patient's head.

[0017] In principle, the distal end of the probe may be tracked inside the patient's body by coupling multiple position sensors of a magnetic position tracking system to the distal end. The position measurements may be calibrated by applying a defined magnetic field using the magnetic position tracking system, and a processor may estimate the position of the position sensors based on position signals acquired during the medical procedure.

[0018] An apparatus including an ENT probe having a plurality of position sensors of a magnetic position tracking system coupled to a distal end of the ENT probe is described in U.S. patent application Ser. No. 15 / 859,969, entitled "Tracking a Rigid Tool in a Patient Body," filed Jan. 2, 2018, which is assigned to the assignee of the present patent application, the disclosure of which is incorporated herein by reference.

[0019] However, in some cases, the magnetic field inside the organ cavity may be distorted by several mechanisms, such as by ferromagnetic portions at the distal end of the probe itself. If the distortions induced in the magnetic field are not taken into account, the distortions may reduce the tracking accuracy of the medical probe within the patient's organ. Furthermore, in the presence of a rotating distal tip, the rotation of the distal position sensor may distort the position signal it generates, either by itself (e.g., by a rotating electric field) or even to any ferromagnetic portions.

[0020] The embodiments of the invention described below provide improved techniques for tracking medical probes, such as ENT tools, that include a portion that creates a change (e.g., distortion) in a magnetic field that intersects with a distal end, within a patient's organ. In some embodiments, the proximal end (e.g., handle) of the disclosed medical probes includes one or more proximal position sensors, and the distal end of the medical probes includes one or more distal position sensors.

[0021] One or more proximal position sensors, mounted in a portion of the probe not significantly affected by the ferromagnetic portion of the distal tip, provide an indication of the position and orientation of the distal tip. One or more distal position sensors mated to the distal tip would likely generate a distorted position signal that would prevent accurate position tracking of the distal tip.

[0022] Because the medical probe is rigid, each of the distal position sensors maintains a constant, known position relative to the proximal position sensor during treatment. In some embodiments, the processor uses the geometrically known relative positions between the multiple position sensors (i.e., the physical relationship of the distal and proximal sensors) to detect, constrain, and correct distorted measurements by the distal sensors along with indications from the proximal sensors to derive an improved indication of the position and orientation of the distal tip.

[0023] In one embodiment, the positions of the one or more distal position sensors relative to the positions of the one or more proximal position sensors are stored in a memory that is accessed by the processor.

[0024] In some embodiments, the processor is configured to correct distorted distal position measurements by the position tracking system by comparing the resulting estimated relative positions of the various sensors with the geometrically known relative positions of the sensors.

[0025] In some embodiments, the processor is configured to initiate a suitable response action, such as alerting a physician, in response to detecting a discrepancy between the known and estimated positions of the distal position sensor relative to the proximal position sensor.

[0026] Typically, the processor is programmed with software that contains specific algorithms that enable the processor to perform each of the processor-related steps and functions outlined above.

[0027] The disclosed technology enables improved quality of minimally invasive medical procedures by enabling magnetic position tracking of medical probes comprising ferromagnetic portions without compromising accuracy in tracking the position of the probe involved.

[0028] System Description 1 is a schematic, pictorial illustration of an ear, nose and throat (ENT) procedure using an ENT module 28 with a navigable shaver, according to one embodiment of the present invention. In some embodiments, an ENT system 20 with an ENT module 28 is configured to perform an ENT procedure, such as treating an infection from one or more sinuses 48 of a patient 22.

[0029] In some embodiments, the ENT module 28 comprises an ENT distal end 38 with a shaver tool at its distal end that the physician 24 inserts into the nose 26 of the patient 22 (shaver tool not shown). The module 28 further comprises a handheld proximal end assembly 30 coupled to a proximal end of the distal end 38 configured to assist the physician 24 in navigating the distal end 38 within the head 41 of the patient 22.

[0030] In one embodiment, system 20 further comprises a magnetic position tracking system configured to track the positions of a plurality of position sensors in and near head 41. The magnetic position tracking system comprises a magnetic field generator 44 and a plurality of position sensors, as shown in Figure 2 below. The position sensors generate position signals in response to sensing an external magnetic field generated by magnetic field generator 44, as described below, thereby enabling processor 34 to estimate the position of each sensor.

[0031] This method of location sensing has been implemented in a variety of medical applications, for example in the CARTO™ system produced by Biosense Webster, Inc. (Irvine, Calif.), and is described in detail in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, in International Publication No. WO 96 / 05768, and in U.S. Patent Application Publication Nos. 2002 / 0065455(A1), 2003 / 0120150(A1), and 2004 / 0068178(A1), the disclosures of all of which are incorporated herein by reference.

[0032] System 20 further comprises a localization pad 40 comprising magnetic field generators 44 fixed to a frame 46. In the exemplary configuration shown in Figure 1, pad 40 comprises five magnetic field generators 44, but may alternatively comprise any other suitable number of generators 44. Pad 40 further comprises a pillow (not shown) placed under head 41 of patient 22 such that generators 44 are positioned at a fixed, known location external to head 41.

[0033] In some embodiments, the system 20 comprises a console 33 comprising a memory 49 and a drive circuit 42 configured to drive a magnetic field generator 44 with a suitable signal via a cable 37 to generate a magnetic field within a defined working volume in the space surrounding the head 41.

[0034] In some embodiments, the console 33 comprises a processor 34, typically a general purpose computer, with suitable front end and interface circuitry for receiving signals from an ENT module 28 having a plurality of magnetic sensors (shown in FIG. 2 below) coupled via a cable 32, as well as for controlling other components of the system 20 described herein.

[0035] In some embodiments, the processor 34 is configured to estimate a position of each position sensor. The processor 34 is configured to derive a position and orientation of the distal end 38 in a coordinate system of the magnetic position tracking system based on the estimated positions of the sensors.

[0036] In some embodiments, the processor 34 is configured to receive, via an interface (not shown), one or more anatomical images, such as CT images representing respective segmented two-dimensional (2D) slices of the head 41, acquired using an external computerized tomography (CT) system (not shown). The term "segmented" refers to the display of different types of tissues identified in each slice by measuring the respective attenuation of the tissues in the CT system.

[0037] The console 33 further comprises an input device 39 for controlling operation of the console, and a user display 36 configured to display data (e.g., images) received from the processor 34 and / or to display inputs inserted by a user (e.g., physician 24) using the input device 39.

[0038] In some embodiments, processor 34 is configured to select one or more modal slices from a CT image, such as image 35, and display the selected slice on user display 36. In the example of FIG. 1, image 35 shows an anterior cross-sectional view of one or more sinuses 48 of patient 22.

[0039] For the sake of brevity and clarity, Fig. 1 shows only elements relevant to the technology of the present disclosure. System 20 typically includes additional modules and elements that are not directly related to the disclosed technology and therefore have been intentionally omitted from Fig. 1 and from the corresponding description.

[0040] The processor 34 may be programmed to perform the functions used by the system and to store in memory 49 data that is processed or otherwise used by the software. This software may be downloaded to the processor in electronic form, for example over a network, or may be provided on a non-transitory tangible medium, such as an optical, magnetic, or electronic memory medium. Alternatively, some or all of the functions of the processor 34 may be performed by dedicated or programmable digital hardware components. In particular, as further explained below, the processor 34 executes the dedicated algorithms disclosed herein, contained in FIG. 3, that enable the processor 34 to perform the disclosed steps.

[0041] ENT Navigable Shaver with Ferromagnetic Components FIG. 2 is a schematic, pictorial illustration of an ENT module 28 used in the ENT procedure of FIG. 1, in accordance with one embodiment of the present invention.

[0042] In some embodiments, the ENT module 28 comprises one or more proximal magnetic position sensors, in this example two sensors designated 50 and 52, coupled at known positions on the handheld proximal end assembly 30. The distal end 38 comprises one or more distal magnetic position sensors, in this example three sensors designated 51, 53, and 55, coupled at known positions on the distal end 38, for example along the longitudinal axis 56 of the shaft 58. In the embodiment shown, the navigation shaver shaft 58 comprises a ferromagnetic material.

[0043] In the context of this disclosure, the term “known positions” refers to the actual positions of sensors 50 and 52 relative to a defined coordinate system of system 20 .

[0044] In one embodiment, the distal end 38 may have a linear configuration, for example as shown in Figure 2. The geometrically known positions of the distal position sensors 51, 53, 55 relative to the sensors 50 and 52 may be defined by a set of vectors 70, one of which between sensors 55 and 50 is shown in Figure 2.

[0045] In other embodiments, any other suitable definitions and measurements may be applied to obtain a known relative position. For example, if the distal end has a curved or irregular shape, the relative position of the distal sensor along the curved shape may be used to better estimate the distal position.

[0046] In some embodiments, the known relative positions of the distal position sensors 51, 53, and 55 with respect to the proximal sensors 50 and 52 are stored in memory 49 of the system 20. The known relative positions may be provided, for example, by the ENT module manufacturer.

[0047] In some embodiments, during an ENT procedure, magnetic field generator 44 applies a magnetic field 60, indicated by magnetic field lines 62. Processor 34 estimates the position of each of distal position sensors 51, 53, and 55 in the coordinate system of the magnetic position tracking system based on signals received from position sensors 51, 53, and 55.

[0048] However, due to the ferromagnetic material of shaft 58, the magnetic field lines 62 in the vicinity of the shaft (shown by dashed lines in FIG. 2) are locally distorted into curved magnetic field lines 72. Proximal position sensors 50 and 52 are not affected by the distorted magnetic field lines 72 and therefore their positions are accurately measured by system 20.

[0049] In some embodiments, processor 34 is configured to calculate an estimated position of each of sensors 51, 53, and 55 relative to the measured positions of sensors 50 and 52 based on the estimated distal positions. The estimated relative positions may be defined, for example, as vector 70 known from the geometry of ENT module 28.

[0050] In some embodiments, the processor 34 stores (in the memory 49 or in the memory of the processor 34) a threshold for determining whether there is a mismatch between a given known vector, such as vector 70, and a corresponding estimated vector that is erroneous, such as a distorted line 72, such as vector 70', causing the position of the sensor 55 to be erroneously estimated as 55'. Examples of thresholds can be a norm, such as distance 71 equal to norm ||70-71'||, and / or an angle. The threshold for determining the mismatch can be different between at least two of the known vectors, or alternatively can be similar for all known vectors.

[0051] In some embodiments, the tool 38 is calibrated with respect to one or more prescribed magnetic fields, typically before performing a procedure, to minimize initial mismatch levels.

[0052] In some embodiments, the processor 34 may initiate a corresponding action when it detects a discrepancy between the estimated distance and the known distance, such as when the norm ||70-71'|| has a value that exceeds a given threshold.

[0053] In one embodiment, in applying the response action, processor 34 may display a warning message, for example on display 36, to physician 24 to delay the ENT procedure.

[0054] In some embodiments, after correcting the distorted position measurements of the distal sensors 51, 53, and 55, the processor 34 displays a message, for example on the user display 36, that the distorted position measurements have been successfully corrected, thereby allowing the physician 24 to proceed with the ENT procedure.

[0055] The configuration of the system ENT module 28 is presented as an example for conceptual clarity, in other embodiments, any alternative configuration, e.g., the number of distal and proximal position sensors may be used, and the distance and orientation between each pair of position sensors may vary, to meet various requirements, such as medical, regulatory, or technical requirements.

[0056] Figure 3 is a flow chart that generally illustrates a method and algorithm for tracking the distal end 38 of the ENT module 28 of Figure 2 within the patient's head 41, in accordance with an embodiment of the present invention. The method begins with a physical measurement step 100, where, for example, a technician, via the ENT module 28, geometrically measures the positions of the distal position sensors 51, 53, and 54 relative to the positions of the proximal position sensors 50 and 52, such as vector 70 depicted above in Figure 2, prior to performing an ENT procedure. In some embodiments, the technician or another user stores the vector 70 in the memory 49 of the console 33.

[0057] In a tool navigation step 102, the physician 24 inserts a navigation shaver fitted to the ENT distal end 38 into the patient's head 41 and receives estimated positions of the sensors 51, 53, and 55 from the processor 34 based on signals measured by the position tracking system.

[0058] In a comparison step 104, the processor 34 uses the proprietary disclosed algorithms, the calculated vector 70', and the measured vector 70 (i.e., comparing the distal and proximal positions) to detect whether there is a discrepancy associated with the position of the distal sensor relative to the proximal sensor (e.g., exceeding one or more specified thresholds).

[0059] In other embodiments, rather than comparing a known vector to an estimated vector, the processor 34 may compare the measured distal positions of the sensors 51, 53 and 55 to the estimated relative positions using any other suitable technique.

[0060] In a mismatch detection step 106, the processor 34 identifies a mismatch between any of the measured (i.e., known) relative position values ​​stored in memory 49 and the estimated relative position values ​​obtained based on the positions of the sensors 51, 53, and 55 measured by the position tracking system.

[0061] If no discrepancy is detected, the method proceeds to navigation completion step 108, where the processor 34 or physician 24 determines whether the ENT distal end 38 is positioned at a target location within the head 41 so that the physician 24 may apply the navigable shaver to perform the ENT procedure.

[0062] If a discrepancy is detected, the method is routed to corresponding action step 112, in which processor 34 notifies physician 24 of the detected discrepancy and, optionally, performs one or more corrective actions, such as correcting a distorted position measurement performed by sensor 51, as described above in FIG. 2.

[0063] In other embodiments, the processor 34 may suggest an action to the user by displaying a suitable message, and / or the physician 24 may decide to terminate the procedure and retract the ENT distal end 38 from the body of the patient 22 as part of the corresponding action performed in step 112.

[0064] If the processor 34 corrects the distorted position measurements performed by the sensors 51, 53 and 55, the method returns to detection step 106, where the processor 34 checks whether all discrepancies detected in step 106 have been corrected, e.g. are now below a defined threshold value.

[0065] If all discrepancies have been corrected, the method is routed to a navigation completion step 108 to determine whether the ENT distal end 38 is positioned at the target location or the method loops back to navigation step 102.

[0066] If navigation is terminated, the method is routed to an ENT procedure step 110, which ends the method. In step 110, the navigable shaver is positioned at a target location on the head 41 (e.g., sinus 48), and the physician 24 may perform an ENT procedure, such as applying the navigable shaver at the ENT to remove infected portions of the sinus 48.

[0067] Although the embodiments described herein primarily address ENT procedures, the methods and systems described herein may also be used in other applications, such as otolaryngology, cardiology, or neurology, that require magnetic tracking of the position and / or orientation of medical devices that include ferromagnetic materials.

[0068] Therefore, it will be understood that the above-described embodiments are cited by way of example, and that the present invention is not limited to what has been particularly shown and described in the above specification. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described in the above specification, as well as variations and modifications thereof not disclosed in the prior art that would occur to one skilled in the art upon reading the foregoing description. Documents incorporated by reference into this patent application shall be considered as an integral part of this application, except that if any term is defined in these incorporated documents in a manner that is inconsistent with the definition expressly or impliedly made herein, then only the definition in this specification shall be considered.

[0069] [Embodiment] (1) A system comprising: 1. A medical probe, comprising: A distal end. one or more distal magnetic position sensors coupled to the distal end; a proximal end assembly; one or more proximal magnetic position sensors coupled to the proximal end assembly; 1. A location tracking system, comprising: a memory configured to hold a value indicative of a known relative position between the distal magnetic position sensor and the proximal magnetic position sensor; and A system comprising: a position tracking system; and a processor configured to receive one or more signals indicative of an estimated position of the proximal magnetic position sensor and the distal magnetic position sensor as measured by the position tracking system, and to initiate a corresponding action in response to detecting a discrepancy between the known relative positions and the estimated positions. (2) The system of embodiment 1, wherein the distal end comprises a portion that generates a change in a magnetic field that intersects with the distal end. (3) The system of embodiment 2, wherein the portion that causes the change in the magnetic field comprises a ferromagnetic material. (4) The system of embodiment 1, wherein the distal position sensor is coupled to a shaft of the medical probe and the proximal magnetic position sensor is coupled to a handle of the medical probe. (5) The device of embodiment 4, wherein the shaft is rotating and the processor is configured to detect the mismatch based on values ​​generated by the one or more rotating distal magnetic position sensors.

[0070] (6) The system of embodiment 1, wherein the processor is configured to correct the detected discrepancy based on the value indicative of the known relative position. (7) The system of embodiment 1, wherein the processor is configured to alert a user of the detected inconsistency. (8) The system of embodiment 1, wherein the processor is configured to compare the value indicating the known relative position with a value indicating the estimated position to detect the discrepancy. (9) The system of claim 1, wherein the medical probe comprises an ear, nose and throat (ENT) tool. (10) A method comprising the steps of: 20. The method of claim 1, further comprising: inserting a medical probe into a patient's organ, the medical probe comprising: A distal end. one or more distal magnetic position sensors coupled to the distal end; a proximal end assembly; and one or more proximal magnetic position sensors coupled to the proximal end assembly. tracking the distal tip using a position tracking system; maintaining a value indicative of a known relative position between the distal magnetic position sensor and the proximal magnetic position sensor; receiving one or more signals indicative of an estimated position of the proximal magnetic position sensor and the distal magnetic position sensor as measured by the position tracking system; and and initiating a corresponding action in response to detecting a discrepancy between the known relative position and the estimated position. A method comprising:

[0071] (11) The method of claim 10, wherein the distal end comprises a portion that produces a change in a magnetic field that intersects with the distal end. (12) The method of claim 11, wherein the portion that causes the change in the magnetic field comprises a ferromagnetic material. (13) The method of claim 10, wherein the distal position sensor is coupled to a shaft of the medical probe and the proximal magnetic position sensor is coupled to a handle of the medical probe. (14) The method of embodiment 13, wherein detecting the discrepancy includes detecting the discrepancy based on values ​​generated by the one or more distal magnetic position sensors coupled to a rotating shaft. (15) The method of embodiment 10, wherein initiating the response action includes correcting the detected discrepancy based on the value indicative of the known relative position.

[0072] (16) The method of embodiment 10, wherein initiating the response action includes alerting a user to the detected inconsistency. (17) The method of claim 10, wherein detecting the discrepancy includes comparing the value indicative of the known relative position with a value of the estimated position. (18) The method of claim 10, wherein the medical probe comprises an ear, nose and throat (ENT) tool and the magnetic position sensor is coupled along a longitudinal axis of the ENT tool. (19) A medical probe comprising: A distal end. one or more distal magnetic position sensors coupled to the distal end; a proximal end assembly; and one or more proximal magnetic position sensors coupled to the proximal end assembly. (20) The medical probe of claim 19, wherein the distal end comprises a portion that produces a change in a magnetic field that intersects with the distal end.

[0073] (21) The medical probe of claim 19, wherein the portion that produces the change in the magnetic field comprises a ferromagnetic material.

Claims

1. 1. A system comprising: (a) a medical probe, comprising: (i) a distal end; and (ii) one or more distal magnetic position sensors coupled to the distal end, the one or more distal magnetic position sensors configured to generate one or more distal position signals; (iii) a proximal end assembly; and (iv) a medical probe comprising: one or more proximal magnetic position sensors coupled to the proximal end assembly, the one or more proximal magnetic position sensors configured to generate one or more proximal position signals; (b) a location tracking system, comprising: (i) a memory configured to hold a value indicative of a known relative position between the one or more distal magnetic position sensors and the one or more proximal magnetic position sensors; (ii) a processor, (A) determining an estimated position of the one or more proximal magnetic position sensors based on the one or more proximal position signals; (B) determining an estimated position of the one or more distal magnetic position sensors based on the one or more distal position signals; (C) determining a geometric position of the one or more distal magnetic position sensors based on the estimated positions of the one or more proximal magnetic position sensors and the known relative positions between the one or more distal magnetic position sensors and the one or more proximal magnetic position sensors; (D) in response to detecting a discrepancy between the estimated positions of the one or more distal magnetic position sensors and the geometric positions of the one or more distal magnetic position sensors, initiate a corresponding action. and a position tracking system comprising a processor configured to:

2. The system of claim 1 , wherein the distal end comprises a portion that produces a change in a magnetic field across the distal end.

3. The system of claim 2 , wherein the portion that produces the change in the magnetic field comprises a ferromagnetic material.

4. 10. The system of claim 1, wherein the one or more distal magnetic position sensors are coupled to a shaft of the medical probe and the one or more proximal magnetic position sensors are coupled to a handle of the medical probe.

5. 5. The system of claim 4, wherein the shaft is rotating and the processor is configured to detect the mismatch based on values ​​produced by the one or more rotating distal magnetic position sensors.

6. The system of claim 1 , wherein the processor is configured to correct the detected discrepancy based on the value indicative of the known relative position.

7. The system of claim 1 , wherein the processor is configured to alert a user of the detected inconsistency.

8. The system of claim 1 , wherein the processor is configured to compare the value indicative of the known relative position with a value of the geometric position to detect the discrepancy.

9. The system of claim 1 , wherein the medical probe comprises an ear, nose and throat (ENT) tool.

10. The system of claim 4 , wherein the shaft comprises a ferromagnetic material.

11. The system of claim 10 , wherein the estimated positions of the one or more proximal magnetic position sensors are measured positions of the one or more proximal magnetic position sensors.

12. The system of claim 1 , wherein the distal end has a curved shape.

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