Opto-magnetic hybrid navigation method and system applied to mandible angulation

Abstract

The invention discloses an optomagnetic hybrid navigation method applied to a mandible angle cutting operation, which comprises the following steps of: fixing an optical mark on an osteotomy tool, and configuring optical equipment for tracking; a six-degree-of-freedom miniature electromagnetic sensor is fixed on the mandible, and electromagnetic equipment is configured for tracking; comprising the following steps: constructing a three-dimensional European coordinate system; based on a homogeneous coordinate transformation matrix # imgabs0 # among different three-dimensional European-style coordinate systems, mapping a cutter pose psSS in a local coordinate system {SS} of the osteotomy cutter to a CT image space; updating the navigation interface in combination with an automatic hybrid navigation strategy based on a distance threshold and a time threshold; and performing accuracy evaluation until a navigation interface meeting a preset condition is output. According to the photomagnetic hybrid mandible angulation operation navigation method, through multi-modal fusion, automatic dynamic adjustment, accurate space registration and equipment calibration and a real-time feedback correction mechanism, the positioning precision, adaptability, consistency and reliability of an operation are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of medical surgery navigation, and more particularly to an optical-magnetic hybrid navigation method and system for mandibular amputation surgery. Background Art

[0002] Mandibular angle reduction surgery is an important oral and maxillofacial surgery, mainly used to treat problems such as mandibular hypertrophy and asymmetry caused by mandibular abnormalities or trauma. This surgery can not only improve the patient's facial contour, but also solve functional disorders caused by mandibular abnormalities, such as chewing difficulties and temporomandibular joint disorders, thereby improving the patient's quality of life.

[0003] In traditional surgery, doctors usually rely on personal experience and manual operation to perform osteotomy. Due to the intraoral approach, the surgical field of view and operating space are very limited, including: it is difficult for doctors to accurately locate the surgical area and osteotomy tool, which can easily cause unnecessary damage to surrounding tissues. It is also difficult to accurately execute surgical planning, resulting in actual results that may deviate from expectations and affect the surgical effect.

[0004] To overcome these limitations, surgical navigation technology was introduced to provide surgeons with accurate anatomical information and operation guidance by real-time tracking of the position of patients and surgical instruments. However, existing single-modality navigation systems (optical or electromagnetic) still have many problems in mandibular osteotomy: they require large markers to be fixed on the mandible and require continuous line of sight, which not only affects the doctor's operation, but is also easily blocked and causes positioning failure. Although line of sight is not required, magnetic osteotomy tools will generate magnetic field interference to electromagnetic sensors, resulting in positioning distortion, and the working range of electromagnetic navigation is narrow.

[0005] In addition, there are differences in data formats, transmission protocols, etc. between different navigation systems, making it difficult to achieve seamless integration and efficient collaboration. This increases the complexity of surgical preparation and the difficulty of operation during surgery. Moreover, most existing navigation systems only evaluate the effect after the operation, and cannot provide doctors with real-time surgical feedback. This may make it difficult for doctors to detect and correct deviations in time during surgery, affecting the quality of surgery and patient safety.

[0006] Therefore, how to design an optical-magnetic hybrid navigation method for mandibular angle reduction surgery to provide doctors with accurate, reliable and flexible navigation assistance during the operation is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0007] In view of this, the present invention provides an optical-magnetic hybrid navigation method for mandibular angle reduction surgery, which effectively overcomes the defects of the existing single-modality navigation system, improves the accuracy and safety of the surgery, and better assists doctors in performing precise and safe surgical operations.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides an optical-magnetic hybrid navigation method for mandibular angle reduction surgery, wherein an optical marker is fixed on the osteotomy tool and an optical device is configured for tracking; a six-degree-of-freedom micro-electromagnetic sensor is fixed on the mandibular bone and an electromagnetic device is configured for tracking;

[0010] The following steps are involved:

[0011] S1. Construct a three-dimensional Euclidean coordinate system; the three-dimensional Euclidean coordinate system includes: an optical device coordinate system {OPT}, an electromagnetic device coordinate system {EM}, an osteotomy tool local coordinate system {SS}, a preoperative CT image coordinate system {CT} and a patient coordinate system {P};

[0012] S2. Define the homogeneous coordinate transformation matrix between different three-dimensional Euclidean coordinate systems

[0013]

[0014] in, is the rotation matrix, is the translation vector;

[0015] S3, based on the homogeneous coordinate transformation matrix between different three-dimensional Euclidean coordinate systems The tool pose ps in the osteotomy tool local coordinate system {SS} SS Mapping to the CT image space and combining with the mandibular 3D model for overlay display to generate a navigation interface;

[0016] S4. updating the navigation interface by combining the automatic hybrid navigation strategy based on the distance threshold and the time threshold to obtain an updated navigation interface;

[0017] S5. Evaluate the accuracy of the updated navigation interface until a navigation interface that meets preset conditions is output.

[0018] Preferably, in S2, the homogeneous coordinate transformation matrix include:

[0019] Homogeneous coordinate transformation matrix between the optical device coordinate system {OPT} and the electromagnetic device coordinate system {EM} Homogeneous coordinate transformation matrix between electromagnetic device coordinate system {EM} and patient coordinate system {P} Homogeneous coordinate transformation matrix between osteotomy tool local coordinate system {SS} and optical device coordinate system {OPT} and the homogeneous coordinate transformation matrix between the preoperative CT image coordinate system {CT} and the patient coordinate system {P}

[0020] Preferably, the homogeneous coordinate transformation matrix Obtained through space registration strategy, including:

[0021] The preoperative CT images are segmented and the three-dimensional surface point cloud of the mandible is reconstructed to obtain the target point cloud {q1, ..., q M};

[0022] Based on the coordinates of the trajectory points on the mandibular surface under the electromagnetic tracking probe, the coordinates of the trajectory points are transformed into the patient coordinate system {P} to obtain the source point cloud {p1, ..., p N};

[0023] The point cloud registration algorithm is used to register the target point cloud {q1, ..., q M} and the source point cloud {p1,…,p N} Perform registration to obtain the transformation matrix from the source point cloud to the target point cloud

[0024] Preferably, the homogeneous coordinate transformation matrix Obtained through device calibration strategy, including:

[0025] An optical local coordinate system {OL} and an electromagnetic local coordinate system {EL} are established under an optical-magnetic hybrid probe; the optical-magnetic hybrid probe is provided with an electromagnetic sensor with six degrees of freedom;

[0026] Obtain the coordinates p of the probe tip at {OL} and {EL} through Pivot calibration OL and p EL ,

[0027] Select N matching point pairs and align them through the point registration algorithm to obtain the homogeneous coordinate transformation matrix

[0028] Preferably, in S3, the tool position ps in the osteotomy tool local coordinate system {SS} SS Obtained through tool calibration strategies, including:

[0029] Based on the coordinate points in the osteotomy tool local coordinate system {SS} under the optical tracking probe, the tool calibration problem is decomposed into the saw plane normal vector calibration and sawtooth point calibration p a 、p b Two sub-questions;

[0030] For saw plane normal vector calibration, pick up N points on the saw blade plane, fit the space plane by the least squares method, and take the normal vector of the space plane as the saw plane normal vector; for saw tooth point calibration, repeatedly pick up the same point M times, and take the average value of the coordinates of the M points as the saw tooth point coordinates;

[0031] Based on the saw plane normal vector and saw tooth point coordinates, the tool pose ps is obtained. SS .

[0032] Preferably, in S3, the tool position ps in the osteotomy tool local coordinate system {SS} is SS Mapped to CT image space, expressed as:

[0033]

[0034] in, represents the tool position expressed in homogeneous coordinates in the osteotomy tool local coordinate system {SS}, Represents the tool pose expressed in homogeneous coordinates in CT image space.

[0035] Preferably, in S4, the automatic hybrid navigation strategy based on the distance threshold and the time threshold includes:

[0036] Based on the distance d between the osteotomy tool and the electromagnetic sensor and the time t when the osteotomy tool continuously loses the optical mark, a preset distance threshold d is defined. th and time threshold t th ;

[0037] Real-time update of homogeneous coordinate transformation matrix Based on the preset distance threshold d th and time threshold t th Alignment secondary coordinate transformation matrix Dynamically adjust based on updates.

[0038] Preferably, the dynamic adjustment includes:

[0039] When d≤d th , or t≤t th When the homogeneous coordinate transformation matrix between the electromagnetic device coordinate system {EM} and the patient coordinate system {P} is stopped renew;

[0040] When d>d th , or t>t th When the homogeneous coordinate transformation matrix between the electromagnetic device coordinate system {EM} and the patient coordinate system {P} is restored renew.

[0041] Preferably, S5 includes:

[0042] Based on the updated navigation interface, the expected anatomical landmarks and the superimposed probe positions are identified and located;

[0043] Calculate the deviation g between the anatomical landmark position and the probe position, and based on the deviation threshold g th Perform accuracy assessment; if g>g th , then repeat the above S2 to S4; otherwise, output the updated navigation interface.

[0044] In a second aspect, the present invention provides an optical-magnetic hybrid navigation system for mandibular angle reduction surgery, comprising:

[0045] Coordinate system construction module: used to construct a three-dimensional Euclidean coordinate system; the three-dimensional Euclidean coordinate system includes: an optical device coordinate system {OPT}, an electromagnetic device coordinate system {EM}, an osteotomy tool local coordinate system {SS}, a preoperative CT image coordinate system {CT} and a patient coordinate system {P};

[0046] Coordinate transformation matrix definition module: used to define homogeneous coordinate transformation matrices between different three-dimensional Euclidean coordinate systems

[0047]

[0048] in, is the rotation matrix, is the translation vector;

[0049] Tool pose mapping module: used for homogeneous coordinate transformation matrices between different 3D Euclidean coordinate systems The tool pose ps in the osteotomy tool local coordinate system {SS} SS Mapping to the CT image space and combining with the mandibular 3D model for overlay display to generate a navigation interface;

[0050] A navigation interface update module: used to update the navigation interface by combining an automatic hybrid navigation strategy based on a distance threshold and a time threshold to obtain an updated navigation interface;

[0051] Navigation interface evaluation module: used to evaluate the accuracy of the updated navigation interface until a navigation interface that meets preset conditions is output.

[0052] It can be seen from the above technical solution that, compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0053] 1. By constructing a multi-dimensional three-dimensional Euclidean coordinate system that includes optical equipment, electromagnetic equipment, local osteotomy tools, preoperative CT images and the patient himself, it can accurately capture and locate every key link in the surgical process, providing a comprehensive spatial reference for the surgery and significantly improving the accuracy and safety of the surgery.

[0054] 2. Using the homogeneous coordinate transformation matrix, the local position of the osteotomy tool can be mapped to the CT image space in real time and superimposed with the three-dimensional model of the mandible, so that users can better understand the progress of the operation and the position of the tool, and make more accurate surgical decisions.

[0055] 3. Considering the complex situations such as signal blocking or loss that may occur during surgery, an automatic hybrid navigation strategy based on distance threshold and time threshold is introduced. It can intelligently switch between optical and electromagnetic navigation modes to ensure that stable and reliable navigation information can be provided to doctors in any situation, greatly improving the robustness and success rate of surgery.

[0056] 4. This method also has the ability to evaluate the accuracy of the navigation interface in real time. By calculating the deviation between the anatomical landmark position and the probe position and making feedback adjustments based on the deviation threshold, the surgical operation can be adjusted in time to ensure the accuracy of the surgical results and the safety of the patient. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0058] Figure 1 A flow chart of the optical-magnetic hybrid navigation method for mandibular angle reduction surgery provided by an embodiment of the present invention;

[0059] Figure 2 A schematic diagram of a three-dimensional Euclidean coordinate system and a homogeneous coordinate transformation matrix provided in an embodiment of the present invention;

[0060] Figure 3 A schematic diagram of a target point cloud provided by an embodiment of the present invention;

[0061] Figure 4 A schematic diagram of a source point cloud provided by an embodiment of the present invention;

[0062] Figure 5 A schematic diagram of a device calibration strategy provided by an embodiment of the present invention;

[0063] Figure 6A schematic diagram of a tool calibration strategy provided by an embodiment of the present invention;

[0064] Figure 7 A schematic diagram of a process of outputting an updated navigation interface provided by an embodiment of the present invention;

[0065] Figure 8 This is a structural diagram of the optical-magnetic hybrid navigation system used in mandibular angle reduction surgery provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] Embodiment 1;

[0068] like Figure 1 and Figure 2 As shown, this embodiment provides an optical-magnetic hybrid navigation method for mandibular angle reduction surgery, wherein an optical marker is fixed on the osteotomy tool and an optical device is configured for tracking; a six-degree-of-freedom micro-electromagnetic sensor is fixed on the mandibular bone and an electromagnetic device is configured for tracking;

[0069] The following is a detailed description of the configuration method:

[0070] Due to the inherent mobility of the mandible, the navigation system needs to track the movement of the osteotomy tool and the mandible at the same time. Optical navigation is more suitable for tracking osteotomy tools, because osteotomy tools are usually magnetically conductive, which will interfere with electromagnetic equipment and cause distortion of its positioning results. On the contrary, electromagnetic navigation is more suitable for tracking the mandible, because optical navigation relies on large markers and is easily blocked, resulting in positioning failure, while electromagnetic navigation only requires micro sensors and does not require line of sight. Therefore, the present invention organically combines optical navigation and electromagnetic navigation, uses optical equipment to track osteotomy tools, and uses electromagnetic navigation to track the mandible, thereby overcoming the limitations of occlusion or electromagnetic interference faced by single-modality navigation systems.

[0071] Specifically, the following steps are included:

[0072] S1. Construct a three-dimensional Euclidean coordinate system; the three-dimensional Euclidean coordinate system includes: an optical device coordinate system {OPT}, an electromagnetic device coordinate system {EM}, an osteotomy tool local coordinate system {SS}, a preoperative CT image coordinate system {CT} and a patient coordinate system {P};

[0073] S2. Define the homogeneous coordinate transformation matrix between different three-dimensional Euclidean coordinate systems

[0074]

[0075] in, is the rotation matrix, is the translation vector;

[0076] S3, based on the homogeneous coordinate transformation matrix between different three-dimensional Euclidean coordinate systems The tool pose ps in the osteotomy tool local coordinate system {SS} SS Mapping to the CT image space and combining with the mandibular 3D model for overlay display to generate a navigation interface;

[0077] S4. updating the navigation interface by combining the automatic hybrid navigation strategy based on the distance threshold and the time threshold to obtain an updated navigation interface;

[0078] S5. Evaluate the accuracy of the updated navigation interface until a navigation interface that meets preset conditions is output.

[0079] This optical-magnetic hybrid mandibular angle reduction surgical navigation method significantly improves the positioning accuracy, adaptability, consistency and reliability of the surgery through multimodal fusion, automated dynamic adjustment, precise spatial registration and equipment calibration, and real-time feedback correction mechanism, thereby effectively assisting doctors in performing more precise and safe surgical operations.

[0080] The above steps and related technical features are further described in detail below:

[0081] In this embodiment S1, the optical device coordinate system (OPT) is used to describe the spatial reference point and axis of the optical navigation device, and is initialized by the optical navigation device itself.

[0082] Electromagnetic device coordinate system (EM): used to describe the spatial reference points and axes of the electromagnetic navigation device, initialized by the electromagnetic navigation device itself.

[0083] Osteotomy tool local coordinate system (SS): used to describe the spatial reference point and axis of the osteotomy tool, initialized by setting optical markers on the tool and identifying them by the optical navigation device.

[0084] Preoperative CT image coordinate system (CT): established based on the patient's preoperative CT image and used to describe the anatomical structure information in the image.

[0085] Patient coordinate system (P): initialized by installing a micro-electromagnetic sensor on the patient's mandible and identifying it with the electromagnetic navigation device, and used to align with the preoperative CT image coordinate system and other coordinate systems.

[0086] These coordinate systems together form a multimodal navigation framework, which provides the basis for subsequent coordinate transformation, pose mapping, and navigation interface generation. By defining these coordinate systems, it is possible to ensure that the spatial relationships between different devices and objects can be accurately represented and transformed.

[0087] In this embodiment S2, in order to accurately convert coordinates and postures between different coordinate systems, a series of homogeneous coordinate transformation matrices need to be defined. These matrices include rotation matrices (describing direction changes) and translation vectors (describing position changes), which together constitute a complete description of the coordinate transformation.

[0088] Homogeneous coordinate transformation matrix between different three-dimensional Euclidean coordinate systems

[0089]

[0090] in, is the rotation matrix, is the translation vector;

[0091] Specific homogeneous coordinate transformation matrix include:

[0092] Homogeneous coordinate transformation matrix between the optical device coordinate system {OPT} and the electromagnetic device coordinate system {EM} Homogeneous coordinate transformation matrix between electromagnetic device coordinate system {EM} and patient coordinate system {P} Homogeneous coordinate transformation matrix between osteotomy tool local coordinate system {SS} and optical device coordinate system {OPT} and the homogeneous coordinate transformation matrix between the preoperative CT image coordinate system {CT} and the patient coordinate system {P}

[0093] Furthermore, the homogeneous coordinate transformation matrix Obtained through space registration strategy, including:

[0094] like Figure 3 As shown in the figure, the preoperative CT image is segmented, and the three-dimensional surface point cloud of the mandible is reconstructed to obtain the target point cloud {q1, ..., q M};

[0095] like Figure 4 As shown, based on the trajectory point coordinates of the mandibular surface under the electromagnetic tracking probe, the trajectory point coordinates are transformed into the patient coordinate system {P} to obtain the source point cloud {p1, ..., p N};

[0096] The point cloud registration algorithm is used to register the target point cloud {q1, ..., q M} and the source point cloud {p1,…,p N} Perform registration to obtain the transformation matrix from the source point cloud to the target point cloud

[0097] Further, such as Figure 5 As shown, the homogeneous coordinate transformation matrix Obtained through device calibration strategy, including:

[0098] An optical local coordinate system {OL} and an electromagnetic local coordinate system {EL} are established under an optical-magnetic hybrid probe; the optical-magnetic hybrid probe is provided with an electromagnetic sensor with six degrees of freedom;

[0099] Obtain the coordinates p of the probe tip at {OL} and {EL} through Pivot calibration OL and p EL ,

[0100] Select N matching point pairs and align them through the point registration algorithm to obtain the homogeneous coordinate transformation matrix

[0101] In addition, regarding the homogeneous coordinate transformation matrix and the homogeneous coordinate transformation matrix

[0102] This technical solution uses two different navigation devices to track the position of key objects during surgery. One is an optical navigation device, which is used to track the osteotomy tool. Its tracking data is recorded as a homogeneous coordinate transformation matrix The other is an electromagnetic navigation device, which is used to track the mandible. Its tracking data is recorded as a homogeneous coordinate transformation matrix

[0103] The above homogeneous coordinate transformation matrix not only includes the rotation matrix (describing the rotation relationship between coordinate systems) and the translation vector (describing the translation relationship between coordinate systems), but also ensures their accuracy and reliability through complex calculations and technical means. Through these transformation matrices, coordinate conversion and posture mapping between different coordinate systems can be realized, providing accurate reference information for subsequent navigation interface generation and surgical operations.

[0104] In this embodiment S3, based on the homogeneous coordinate transformation matrix ′ between different three-dimensional Euclidean coordinate systems The tool pose ps in the osteotomy tool local coordinate system {SS} SS Mapping to the CT image space and combining with the mandibular 3D model for overlay display to generate a navigation interface;

[0105] Among them, Figure 6 As shown, the tool position ps in the osteotomy tool local coordinate system {SS} SS Obtained through tool calibration strategies, including:

[0106] Based on the coordinate points in the osteotomy tool local coordinate system {SS} under the optical tracking probe, the tool calibration problem is decomposed into the saw plane normal vector calibration and sawtooth point calibration p a 、p b Two sub-questions;

[0107] For saw plane normal vector calibration, pick up N points on the saw blade plane, fit the space plane by the least squares method, and take the normal vector of the space plane as the saw plane normal vector; for saw tooth point calibration, repeatedly pick up the same point M times, and take the average value of the coordinates of the M points as the saw tooth point coordinates;

[0108] Based on the saw plane normal vector and saw tooth point coordinates, the tool pose ps is obtained. SS .

[0109] Furthermore, the tool position ps in the osteotomy tool local coordinate system {SS} SS Mapped to CT image space, expressed as:

[0110]

[0111] in, represents the tool position expressed in homogeneous coordinates in the osteotomy tool local coordinate system {SS}, Represents the tool pose expressed in homogeneous coordinates in CT image space.

[0112] It is necessary to first transform the tool position ps in the osteotomy tool local coordinate system {SS} SS Convert to the optical device coordinate system {OPT}, then to the electromagnetic device coordinate system {EM}, then to the patient coordinate system {P}, and finally to the preoperative CT image coordinate system {CT). In this way, we can get the tool pose in the CT image space

[0113] The mapping process in this step is achieved through a series of coordinate transformations, and each transformation matrix corresponds to a specific coordinate system transformation relationship. In this way, we can ensure that during the operation, the doctor can see the actual position and movement of the tool on the CT image, so as to perform the operation more accurately.

[0114] Furthermore, the navigation interface should not only display the real-time position and direction of the osteotomy tool in the CT image space, but also distinguish different tissue structures (such as mandible, blood vessels, nerves, etc.) through different colors, transparency or textures to provide a more intuitive and comprehensive surgical field of view.

[0115] The user is allowed to rotate, zoom, and translate the navigation interface through a touch screen or a handle to observe the surgical area from different angles and distances. At the same time, a marking tool is provided to allow doctors to mark key anatomical structures or surgical paths on the navigation interface.

[0116] In this embodiment S4, in order to ensure the stability and accuracy of the navigation system, an automatic hybrid navigation strategy based on distance threshold and time threshold is introduced. This strategy dynamically adjusts the update mode of navigation data by real-time monitoring the distance between the osteotomy tool and the electromagnetic sensor and the time when the osteotomy tool continuously loses the optical marker, thereby ensuring the accuracy and reliability of the navigation interface.

[0117] Specifically, the automatic hybrid navigation strategy based on distance threshold and time threshold includes:

[0118] Based on the distance d between the osteotomy tool and the electromagnetic sensor and the time t when the osteotomy tool continuously loses the optical mark, a preset distance threshold d is defined. th and time threshold t th ; specific, d th 100mm, t th 5s.

[0119] Real-time update of homogeneous coordinate transformation matrix Based on the preset distance threshold d th and time threshold t th Alignment secondary coordinate transformation matrix Dynamically adjust based on updates.

[0120] The setting of the distance threshold should take into account the degree of interference of the magnetic osteotomy tool on the electromagnetic sensor positioning data, as well as the accuracy requirements of the surgical operation. When the tool is too close to the sensor, it will interfere with the electromagnetic field near it, causing distortion of its positioning data. At this time, optical navigation should be used first. The setting of the time threshold is based on the average recovery time of the optical marker being blocked and the tolerance of the surgical operation. If the optical marker is lost for too long, it may mean that there is a serious occlusion problem at the current surgical location. At this time, electromagnetic navigation should be temporarily relied on until the optical marker is restored.

[0121] Further, dynamic adjustments include:

[0122] When d≤d th , or t≤t th When the homogeneous coordinate transformation matrix between the electromagnetic device coordinate system {EM} and the patient coordinate system {P} is stopped Update; rely on optical navigation instead. At this time, the interface clearly reminds the user that it is currently in optical navigation mode and displays relevant precautions.

[0123] When d>dth , or t>t th When the homogeneous coordinate transformation matrix between the electromagnetic device coordinate system {EM} and the patient coordinate system {P} is restored Update. At this point, switch back to hybrid navigation mode. At this point, the interface updates to reflect the latest navigation information and prompts the user that navigation mode has been restored.

[0124] During the navigation mode switching process, the smoothness of interface updates should be ensured to avoid sudden changes that may cause trouble to users.

[0125] In this step, at any time, only one of d and t is valid. This is because d calculates the distance from the osteotomy tool to the electromagnetic sensor, and t represents the continuous loss time of the osteotomy tool. If t is valid, the osteotomy tool is lost, and the distance d cannot be calculated. If d is valid, the osteotomy tool is not lost, and t is 0.

[0126] According to the actual conditions that may be encountered during surgery (such as optical marker occlusion, electromagnetic signal interference, etc.), the navigation system usage mode is dynamically adjusted to ensure the continuity and accuracy of the surgery. By setting reasonable distance thresholds and time thresholds, the system can intelligently determine the most suitable navigation method at the moment and switch seamlessly between the two navigation modes.

[0127] In this embodiment, Figure 7 As shown, S5 includes:

[0128] Based on the updated navigation interface, the expected anatomical landmarks and the superimposed probe positions are identified and located;

[0129] Calculate the deviation g between the anatomical landmark position and the probe position, and based on the deviation threshold g th Perform accuracy assessment; if g>g th , then repeat the above S2 to S4; otherwise, output the updated navigation interface.

[0130] Specifically, before identifying the anatomical landmarks, the updated navigation interface is first subjected to image preprocessing, including operations such as denoising and contrast enhancement, to improve the accuracy of landmark recognition.

[0131] Image processing technology (such as edge detection and texture analysis) is used to extract feature information in the navigation interface, and a template library of anatomical landmarks is established. The template matching algorithm is used to find the area that best matches the template in the preprocessed navigation interface to determine the location of the landmark.

[0132] The deviation g includes: position deviation (the straight-line distance between the position of the anatomical landmark and the position of the probe) and direction deviation (the angle between the line connecting the two and the expected surgical path).

[0133] The calculated deviation value is compared with the preset deviation threshold. If the deviation value exceeds the threshold, it is considered that the current surgical path or probe position needs to be adjusted; otherwise, the updated navigation interface is output and the current state meets the surgical requirements.

[0134] Embodiment 2;

[0135] like Figure 8 As shown, this embodiment provides an optical-magnetic hybrid navigation system for mandibular angle reduction surgery, comprising:

[0136] Coordinate system construction module: used to construct a three-dimensional Euclidean coordinate system; the three-dimensional Euclidean coordinate system includes: an optical device coordinate system {OPT}, an electromagnetic device coordinate system {EM}, an osteotomy tool local coordinate system {SS}, a preoperative CT image coordinate system {CT} and a patient coordinate system {P};

[0137] Coordinate transformation matrix definition module: used to define homogeneous coordinate transformation matrices between different three-dimensional Euclidean coordinate systems

[0138]

[0139] in, is the rotation matrix, is the translation vector;

[0140] Tool pose mapping module: used for homogeneous coordinate transformation matrices between different 3D Euclidean coordinate systems The tool pose ps in the osteotomy tool local coordinate system {SS} SS Mapping to the CT image space and combining with the mandibular 3D model for overlay display to generate a navigation interface;

[0141] A navigation interface update module: used to update the navigation interface by combining an automatic hybrid navigation strategy based on a distance threshold and a time threshold to obtain an updated navigation interface;

[0142] Navigation interface evaluation module: used to evaluate the accuracy of the updated navigation interface until a navigation interface that meets preset conditions is output.

[0143] The system integrates multiple key modules to achieve high-precision surgical navigation. First, a multi-dimensional three-dimensional Euclidean coordinate system including optical equipment, electromagnetic equipment, local osteotomy tools, preoperative CT images and the patient himself is established through the coordinate system construction module. Subsequently, the coordinate transformation matrix definition module defines the homogeneous coordinate transformation matrix between these coordinate systems to ensure accurate conversion between each coordinate system. The tool posture mapping module uses these transformation matrices to map the local posture of the osteotomy tool to the CT image space, and superimposes it with the three-dimensional model of the mandible to generate an intuitive navigation interface. The navigation interface update module combines the automatic hybrid navigation strategy based on distance threshold and time threshold to update the navigation interface in real time to adapt to dynamic changes during the operation. Finally, the navigation interface evaluation module evaluates the accuracy of the updated navigation interface to ensure that it is output only after the preset conditions are met, thereby ensuring the accuracy and safety of the operation.

[0144] The optical-magnetic hybrid navigation system provided in this embodiment realizes the full-process automation from coordinate system establishment to navigation interface generation and update through the collaborative work of multiple functional modules, which greatly improves the accuracy and safety of mandibular angle reduction surgery.

[0145] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0146] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optical-magnetic hybrid navigation method for mandibular angle reduction surgery, characterized in that: An optical marker is fixed on the osteotomy tool, and an optical device is configured for tracking; a six-degree-of-freedom micro-electromagnetic sensor is fixed on the mandible, and an electromagnetic device is configured for tracking; The following steps are involved: S1, constructing a three-dimensional Euclidean coordinate system; the three-dimensional Euclidean coordinate system includes: an optical device coordinate system OPT}, an electromagnetic device coordinate system {EM}, an osteotomy tool local coordinate system {SS}, a preoperative CT image coordinate system {CT} and a patient coordinate system {P}; S2. Define the homogeneous coordinate transformation matrix between different three-dimensional Euclidean coordinate systems in, is the rotation matrix, is the translation vector; S3, based on the homogeneous coordinate transformation matrix between different three-dimensional Euclidean coordinate systems The tool pose ps in the osteotomy tool local coordinate system [SS} SS Mapping to the CT image space and combining with the mandibular 3D model for overlay display to generate a navigation interface; S4. updating the navigation interface by combining the automatic hybrid navigation strategy based on the distance threshold and the time threshold to obtain an updated navigation interface; S5. Evaluate the accuracy of the updated navigation interface until a navigation interface that meets preset conditions is output.

2. The optical-magnetic hybrid navigation method for mandibular angle reduction surgery according to claim 1, characterized in that: In S2, the homogeneous coordinate transformation matrix include: Homogeneous coordinate transformation matrix between the optical device coordinate system [OPT} and the electromagnetic device coordinate system {EM} Homogeneous coordinate transformation matrix between electromagnetic device coordinate system {EM} and patient coordinate system {P} Homogeneous coordinate transformation matrix between osteotomy tool local coordinate system {SS} and optical device coordinate system {OPT} and the homogeneous coordinate transformation matrix between the preoperative CT image coordinate system {CT} and the patient coordinate system {P} 3. The optical-magnetic hybrid navigation method for mandibular angle reduction surgery according to claim 2, characterized in that: The homogeneous coordinate transformation matrix Obtained through space registration strategy, including: The preoperative CT images are segmented and the three-dimensional surface point cloud of the mandible is reconstructed to obtain the target point cloud {q1,…,q M }; Based on the coordinates of the trajectory points on the mandibular surface under the electromagnetic tracking probe, the trajectory point coordinates are transformed into the patient coordinate system {P} to obtain the source point cloud {p1,…,p N }; The point cloud registration algorithm is used to register the target point cloud {q1,…,q M } and the source point cloud {p1,…,p N } Perform registration to obtain the transformation matrix from the source point cloud to the target point cloud 4. The optical-magnetic hybrid navigation method for mandibular angle reduction surgery according to claim 2, characterized in that: The homogeneous coordinate transformation matrix Obtained through device calibration strategy, including: An optical local coordinate system {OL} and an electromagnetic local coordinate system {EL} are established under an optical-magnetic hybrid probe; the optical-magnetic hybrid probe is provided with an electromagnetic sensor with six degrees of freedom; Obtain the coordinates p of the probe tip at {OL} and {EL} through Pivot calibration OL and p EL , Select N matching point pairs and align them through the point registration algorithm to obtain the homogeneous coordinate transformation matrix 5. The optical-magnetic hybrid navigation method for mandibular angle reduction surgery according to claim 1, characterized in that: In S3, the tool position ps in the osteotomy tool local coordinate system {SS} SS Obtained through tool calibration strategies, including: Based on the coordinate points in the osteotomy tool local coordinate system {SS} under the optical tracking probe, the tool calibration problem is decomposed into the saw plane normal vector calibration and sawtooth point calibration p a 、p b Two sub-questions; For saw plane normal vector calibration, pick up N points on the saw blade plane, fit the space plane by the least squares method, and take the normal vector of the space plane as the saw plane normal vector; for saw tooth point calibration, repeatedly pick up the same point M times, and take the average value of the coordinates of the M points as the saw tooth point coordinates; Based on the saw plane normal vector and saw tooth point coordinates, the tool pose ps is obtained. SS .

6. The optical-magnetic hybrid navigation method for mandibular angle reduction surgery according to claim 1, characterized in that: In S3, the tool position ps in the osteotomy tool local coordinate system {SS} is SS Mapped to CT image space, expressed as: in, represents the tool position expressed in homogeneous coordinates in the osteotomy tool local coordinate system {SS}, Represents the tool pose expressed in homogeneous coordinates in CT image space.

7. The optical-magnetic hybrid navigation method for mandibular angle reduction surgery according to claim 1, characterized in that: In S4, the automatic hybrid navigation strategy based on the distance threshold and the time threshold includes: Based on the distance d between the osteotomy tool and the electromagnetic sensor and the time t when the osteotomy tool continuously loses the optical mark, a preset distance threshold d is defined. th and time threshold t th ; Real-time update of homogeneous coordinate transformation matrix Based on the preset distance threshold d th and time threshold t th Alignment secondary coordinate transformation matrix Dynamically adjust based on updates.

8. The optical-magnetic hybrid navigation method for mandibular angle reduction surgery according to claim 7, characterized in that: The dynamic adjustment includes: When d≤d th , or t≤t th When the homogeneous coordinate transformation matrix between the electromagnetic device coordinate system {EM} and the patient coordinate system {P} is stopped renew; When d>d th , or t>t th When the homogeneous coordinate transformation matrix between the electromagnetic device coordinate system {EM} and the patient coordinate system {P} is restored renew.

9. The optical-magnetic hybrid navigation method for mandibular angle reduction surgery according to claim 1, characterized in that: The S5 includes: Based on the updated navigation interface, the expected anatomical landmarks and the superimposed probe positions are identified and located; Calculate the deviation g between the anatomical landmark position and the probe position, and based on the deviation threshold g th Perform accuracy assessment; if g>g th , then repeat the above S2 to S4; otherwise, output the updated navigation interface.

10. An optical-magnetic hybrid navigation system for mandibular angle reduction surgery, characterized in that: include: Coordinate system construction module: used to construct a three-dimensional Euclidean coordinate system; The three-dimensional Euclidean coordinate system includes: an optical device coordinate system {OPT}, an electromagnetic device coordinate system {EM}, an osteotomy tool local coordinate system {SS}, a preoperative CT image coordinate system {CT} and a patient coordinate system {P}; Coordinate transformation matrix definition module: used to define homogeneous coordinate transformation matrices between different three-dimensional Euclidean coordinate systems in, is the rotation matrix, is the translation vector; Tool pose mapping module: used for homogeneous coordinate transformation matrices between different 3D Euclidean coordinate systems The tool pose ps in the osteotomy tool local coordinate system {SS} SS Mapping to the CT image space and combining with the mandibular 3D model for overlay display to generate a navigation interface; A navigation interface update module: used to update the navigation interface by combining an automatic hybrid navigation strategy based on a distance threshold and a time threshold to obtain an updated navigation interface; Navigation interface evaluation module: used to evaluate the accuracy of the updated navigation interface until a navigation interface that meets preset conditions is output.

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