An optical-magnetic hybrid navigation method and system for mandibular angle reduction surgery

Abstract

The present invention discloses an optical-magnetic hybrid navigation method for mandibular angle reduction surgery. 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 method comprises the following steps: constructing a three-dimensional Euclidean coordinate system; transforming the tool position ps in the local coordinate system {SS} of the osteotomy tool based on the homogeneous coordinate transformation matrix between different three-dimensional Euclidean coordinate systems; SS The navigation interface is then mapped to the CT image space; an automatic hybrid navigation strategy based on distance and time thresholds is used to update the navigation interface; and accuracy is evaluated until a navigation interface that meets preset conditions is output. This optical-magnetic hybrid mandibular angle reduction surgical navigation method significantly improves surgical positioning accuracy, adaptability, consistency, and reliability through multimodal fusion, automated dynamic adjustment, precise spatial registration and device calibration, and a real-time feedback correction mechanism.

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 angle amputation surgery. Background Art

[0002] Mandibular angle reduction surgery is an important oral and maxillofacial surgical procedure primarily used to treat problems such as enlarged and asymmetrical mandibular angles caused by mandibular developmental abnormalities or trauma. This surgery not only improves the patient's facial contour but also addresses functional impairments caused by mandibular abnormalities, such as chewing difficulties and temporomandibular joint disorders, thereby improving the patient's quality of life.

[0003] In traditional osteotomy, surgeons typically rely on personal experience and manual manipulation. Due to the intraoral approach, the surgical field of view and operating space are very limited. This can make it difficult for surgeons to accurately position the surgical area and osteotomy tool, potentially causing unnecessary damage to surrounding tissue. Furthermore, precise execution of surgical plans can be difficult, resulting in deviations from expected outcomes and compromising surgical effectiveness.

[0004] To overcome these limitations, surgical navigation technology has been introduced to provide surgeons with precise anatomical information and operational guidance by tracking the position of the patient and surgical instruments in real time. 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 obstructed, leading to positioning failure. Although line of sight is not required, magnetic osteotomy tools will generate magnetic field interference on electromagnetic sensors, resulting in positioning distortion, and the working range of electromagnetic navigation is narrow.

[0005] Furthermore, differences in data formats and transmission protocols between different navigation systems hinder seamless integration and efficient collaboration. This complicates surgical preparation and increases the difficulty of performing the procedure. Furthermore, existing navigation systems often evaluate surgical outcomes only after the procedure is complete, failing to provide real-time surgical feedback. This can make it difficult for doctors to detect and correct deviations during surgery, compromising surgical quality and patient safety.

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

[0007] In view of this, the present invention provides an optical-magnetic hybrid navigation method for mandibular angle resection 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 solutions:

[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. 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};

[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 it with the mandibular 3D model for overlay display to generate a navigation interface;

[0016] S4. updating 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;

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

[0018] Preferably, in said 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 the electromagnetic device coordinate system {EM} and the patient coordinate system {P} Homogeneous coordinate transformation matrix between the osteotomy tool local coordinate system {SS} and the 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 policy, including:

[0021] Perform image segmentation on the preoperative CT image and reconstruct the three-dimensional surface point cloud of the mandible to obtain the target point cloud {q1, ..., q M};

[0022] 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};

[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] Establishing an optical local coordinate system {OL} and an electromagnetic local coordinate system {EL} under an optical-magnetic hybrid probe; the optical-magnetic hybrid probe is equipped with a six-degree-of-freedom electromagnetic sensor;

[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 using the point registration algorithm to obtain the homogeneous coordinate transformation matrix

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

[0029] Based on the coordinate points in the local coordinate system {SS} of the osteotomy tool 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 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 the same point M times, and take the average value of the coordinates of the M points as the saw tooth point coordinate;

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

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

[0033]

[0034] in, represents the tool pose expressed in homogeneous coordinates in the local coordinate system {SS} of the osteotomy tool, Represents the tool pose expressed in homogeneous coordinates in the 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 And based on the preset distance threshold d th and time threshold t th Align secondary coordinate transformation matrix Dynamic adjustment 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, the 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 S2 to S4 above; 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 it with the mandibular 3D model for overlay display to generate a navigation interface;

[0050] A navigation interface update module is configured 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 the output is a navigation interface that meets the preset conditions.

[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 a 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 3D model of the mandible. This allows the user to better understand the surgical progress and tool position, allowing for more accurate surgical decisions.

[0055] 3. Considering complex situations such as signal obstruction or loss that may occur during surgery, an automatic hybrid navigation strategy based on distance and time thresholds has been introduced. This strategy intelligently switches between optical and electromagnetic navigation modes, ensuring stable and reliable navigation information for surgeons in all situations, significantly improving the robustness and success rate of surgery.

[0056] 4. This method also has the ability to perform real-time accuracy assessment of the navigation interface. By calculating the deviation between the anatomical landmark position and the probe position and providing feedback based on the deviation threshold, the surgical procedure can be adjusted in a timely manner to ensure the accuracy of the surgical outcome and patient safety. 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any 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 the 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 clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0067] Example 1;

[0068] like Figure 1 and Figure 2 As shown, this embodiment provides an optical-magnetic hybrid navigation method for mandibular angle reduction surgery. 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. For tracking osteotomy tools, optical navigation is more suitable, because osteotomy tools are usually magnetic and will interfere with electromagnetic equipment, causing distortion of its positioning results. On the contrary, for tracking the mandible, electromagnetic navigation is more suitable, 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. 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};

[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 it with the mandibular 3D model for overlay display to generate a navigation interface;

[0077] S4. updating 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;

[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, an 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] Together, these coordinate systems form a multimodal navigation framework, providing the foundation for subsequent coordinate transformations, pose mapping, and navigation interface generation. By defining these coordinate systems, we 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 poses between different coordinate systems, it is necessary to define a series of homogeneous coordinate transformation matrices. These matrices include rotation matrices (describing changes in orientation) and translation vectors (describing changes in position), 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 the electromagnetic device coordinate system {EM} and the patient coordinate system {P} Homogeneous coordinate transformation matrix between the osteotomy tool local coordinate system {SS} and the 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 policy, 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 in the figure, 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] Establishing an optical local coordinate system {OL} and an electromagnetic local coordinate system {EL} under an optical-magnetic hybrid probe; the optical-magnetic hybrid probe is equipped with a six-degree-of-freedom electromagnetic sensor;

[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 using 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 homogeneous coordinate transformation matrix described above not only includes rotation matrices (describing the rotational relationship between coordinate systems) and translation vectors (describing the translational relationship between coordinate systems), but also uses complex calculations and technical means to ensure their accuracy and reliability. These transformation matrices enable coordinate conversion and pose mapping between different coordinate systems, providing precise 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 it with the mandibular 3D model for overlay display to generate a navigation interface;

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

[0106] Based on the coordinate points in the local coordinate system {SS} of the osteotomy tool 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 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 the same point M times, and take the average value of the coordinates of the M points as the saw tooth point coordinate;

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

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

[0110]

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

[0112] It is necessary to first transform the tool position ps in the local coordinate system {SS} of the osteotomy tool 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, with each transformation matrix corresponding to a specific coordinate system transformation relationship. This ensures that during surgery, the surgeon can see the actual position and movement of the tool on the CT image, allowing for more precise surgical operations.

[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 pan the navigation interface through a touch screen or handle to observe the surgical area from different angles and distances. At the same time, a marking tool is provided to allow the doctor to mark key anatomical structures or surgical paths on the navigation interface.

[0116] In this embodiment S4, to ensure the stability and accuracy of the navigation system, an automatic hybrid navigation strategy based on distance and time thresholds is introduced. This strategy dynamically adjusts the navigation data update method by monitoring the distance between the osteotomy tool and the electromagnetic sensor in real time, as well as 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 And based on the preset distance threshold d th and time threshold t th Align secondary coordinate transformation matrix Dynamic adjustment based on updates.

[0120] The distance threshold should be set based on the degree of interference the magnetic osteotomy tool may have on the electromagnetic sensor's positioning data, while also considering the precision required for the surgical procedure. When the tool is too close to the sensor, it interferes with the electromagnetic field nearby, distorting the positioning data. Optical navigation should be prioritized in this situation. The time threshold is set based on the average recovery time after an optical marker is obscured and the tolerance for surgical procedures. If the optical marker is lost for an extended period of time, it may indicate a severe obstruction at the current surgical site. In this case, electromagnetic navigation should be temporarily relied upon 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 interface should be updated smoothly to avoid sudden changes that may cause trouble to users.

[0125] In this step, at any given moment, only one of d and t is valid. This is because d measures the distance from the osteotomy tool to the electromagnetic sensor, while t represents the duration of the tool's loss. If t is valid, the osteotomy tool is lost, and distance d cannot be calculated. If d is valid, the osteotomy tool is not lost, and t is 0.

[0126] Based on specific circumstances that may be encountered during surgery (such as optical marker obstruction and electromagnetic signal interference), the navigation system's usage mode is dynamically adjusted to ensure continuity and accuracy. By setting appropriate distance and time thresholds, the system intelligently determines the most appropriate navigation method and seamlessly switches 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 S2 to S4 above; otherwise, output the updated navigation interface.

[0130] Specifically, before identifying 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 from 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 position 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] Example 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 it with the mandibular 3D model for overlay display to generate a navigation interface;

[0141] A navigation interface update module is configured 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 the output is a navigation interface that meets the preset conditions.

[0143] The system integrates multiple key modules to achieve high-precision surgical navigation. First, the coordinate system construction module establishes a multidimensional three-dimensional Euclidean coordinate system that includes optical equipment, electromagnetic equipment, local osteotomy tools, preoperative CT images, and the patient himself. Subsequently, the coordinate transformation matrix definition module defines the homogeneous coordinate transformation matrices 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 overlays it with the three-dimensional model of the mandible to generate an intuitive navigation interface. The navigation interface update module combines an automatic hybrid navigation strategy based on distance thresholds and time thresholds to update the navigation interface in real time to adapt to dynamic changes during the surgery. Finally, the navigation interface evaluation module evaluates the accuracy of the updated navigation interface to ensure that it is output only when the preset conditions are met, thereby ensuring the accuracy and safety of the surgery.

[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, greatly improving the accuracy and safety of mandibular resection surgery.

[0145] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. References to the same or similar parts between the various embodiments are sufficient. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For relevant parts, refer to the method description.

[0146] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily 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 is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 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; The homogeneous coordinate transformation matrix Includes: Homogeneous coordinate transformation matrix between the optical device coordinate system {OPT} and the electromagnetic device coordinate system {EM} , the homogeneous coordinate transformation matrix between the electromagnetic device coordinate system {EM} and the patient coordinate system {P} , the homogeneous coordinate transformation matrix between the osteotomy tool local coordinate system {SS} and the 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} ; Tool pose mapping module: used for homogeneous coordinate transformation matrices between different 3D Euclidean coordinate systems , the tool pose in the osteotomy tool local coordinate system {SS} Mapping to the CT image space and combining it with the mandibular 3D model for overlay display to generate a navigation interface; A navigation interface update module is configured 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; The automatic hybrid navigation strategy based on distance threshold and time threshold includes: defining a preset distance threshold d 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 marker th and time threshold t th ; Update the homogeneous coordinate transformation matrix in real time , and based on the preset distance threshold d th and time threshold t th Align secondary coordinate transformation matrix Dynamic adjustment of updates; 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 Update; 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; Navigation interface evaluation module: used to evaluate the accuracy of the updated navigation interface until the output is a navigation interface that meets the preset conditions.

2. The optical-magnetic hybrid navigation system for mandibular angle reduction surgery according to claim 1, characterized in that: The homogeneous coordinate transformation matrix Obtained through space registration policy, including: Perform image segmentation on preoperative CT images, reconstruct the three-dimensional surface point cloud of the mandible, and obtain the target point cloud ; 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 ; The target point cloud is registered using the point cloud registration algorithm and source point cloud Perform registration to obtain the transformation matrix from the source point cloud to the target point cloud .

3. The optical-magnetic hybrid navigation system for mandibular angle reduction surgery according to claim 1, characterized in that: The homogeneous coordinate transformation matrix Obtained through device calibration strategy, including: Establishing an optical local coordinate system {OL} and an electromagnetic local coordinate system {EL} under an optical-magnetic hybrid probe; the optical-magnetic hybrid probe is equipped with a six-degree-of-freedom electromagnetic sensor; 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 using the point registration algorithm to obtain the homogeneous coordinate transformation matrix .

4. The optical-magnetic hybrid navigation system for mandibular angle reduction surgery according to claim 1, characterized in that: The tool pose ps in the osteotomy tool local coordinate system {SS} SS Obtained through tool calibration strategies, including: Based on the coordinate points in the local coordinate system {SS} of the osteotomy tool under the optical tracking probe, the tool calibration problem is decomposed into the saw plane normal vector calibration and two sub-problems of sawtooth point calibration; For saw plane normal vector calibration, pick 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 the same point M times, and take the average value of the coordinates of the M points as the saw tooth point coordinate; Based on the saw plane normal vector and saw tooth point coordinates, the tool pose ps is obtained SS .

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

6. The optical-magnetic hybrid navigation system for mandibular angle reduction surgery according to claim 1, characterized in that: The output of the navigation interface that meets the preset conditions 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 Conduct accuracy assessment.

Images