Method and apparatus for measuring the effective range of a magnetic field generator

Abstract

The application discloses a method and device for measuring the effective range of a magnetic field generator, which can measure the high-precision tracking range of the magnetic field generator in electromagnetic navigation technology, so as to provide the tracking range under different tracking precisions for a doctor when the doctor uses the electromagnetic navigation technology to perform an operation, and to screen the operation modes which can perform the required precision under different precisions. The method comprises the following steps: (1) installing the magnetic field generator into a magnetic field generator positioning groove of a range measurement working device; (2) installing a movable measurement plate according to the required measurement of the spatial position of the magnetic field space; (3) converting the CT image of the movable measurement plate to the magnetic field space coordinate system by using a magnetic positioning rigid image registration module; (4) calculating the tracking error of each mark point by using a calculation error module, moving the position of the movable measurement plate if the spatial position of the required measurement of the magnetic field space is not completed, repeating steps (2)-(4), and performing step (5) if all the measurements are completed; and (5) outputting the range meeting the tracking error requirement.

Description

Technical Field

[0001] This invention relates to the technical field of electromagnetic navigation, and more particularly to a method for measuring the effective range of a magnetic field generator, as well as an apparatus for measuring the effective range of a magnetic field generator. Background Technology

[0002] Navigation technology utilizes physical principles and methods such as electricity, magnetism, optics, and force to locate moving objects and guide them correctly from their starting point along a predetermined route to their destination safely and accurately. The rapid development and widespread application of navigation technology in various fields have greatly facilitated human life. Compared to optical navigation technology, electromagnetic navigation technology effectively avoids the adverse effects of surgical instruments being obstructed during surgery and features high response speed and good real-time performance. Electromagnetic navigation technology is already being used in the medical field to assist doctors in surgical navigation. In electromagnetic navigation technology, a magnetic field generator constructs a spatial magnetic field through electrical signals, and an electromagnetic receiver receives the corresponding magnetic field signal in space according to the law of electromagnetic induction, using conversion relationships to solve for the current pose information. The magnetic field generator acts as the "eyes" of the electromagnetic navigation system; the higher the accuracy of the spatial magnetic field constructed by the magnetic field generator, the more it determines the tracking effect of the electromagnetic navigation system.

[0003] During surgery, electromagnetic tracking technology is used to precisely track the current position of surgical instruments and display it in a pre-built 3D model. Doctors can then observe the surgical parameters from all directions, thereby avoiding dangerous areas to the greatest extent possible and reducing surgical trauma and complications.

[0004] In some surgical procedures, surgeons face lesions located only millimeters apart from normal organs; therefore, electromagnetic navigation in surgical navigation requires precision sufficient for the procedure. Due to the non-uniform nature of spatial magnetic fields, navigation accuracy varies at different locations within a given magnetic field. Therefore, it is necessary to determine the effective navigation range of the magnetic field generator to meet the required precision for the specific surgical procedure. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method for measuring the effective range of a magnetic field generator, which can measure the high-precision tracking range of the magnetic field generator in electromagnetic navigation technology. This allows doctors to provide tracking ranges at different tracking accuracies when using electromagnetic navigation technology for surgery, thereby selecting surgical procedures that can be performed with the required precision at different accuracies, and ensuring the safety of the surgery.

[0006] The technical solution of this invention is: a method for measuring the effective range of a magnetic field generator, comprising the following steps:

[0007] (1) Install the magnetic field generator into the positioning slot of the magnetic field generator of the range measurement working device;

[0008] (2) Install a movable measuring plate to measure the spatial position of the magnetic field as needed;

[0009] (3) Use the magnetic positioning rigid image registration module to convert the CT images of the movable measuring plate into the magnetic field space coordinate system;

[0010] (4) Use the error calculation module to calculate the tracking error of each marker point. If the spatial position of the magnetic field space to be measured is not completed, move the position of the movable measuring plate and repeat steps (2)-(4). If all the magnetic field spaces to be measured are completed, execute step (5).

[0011] (5) Output the range that meets the tracking error requirements.

[0012] This invention utilizes a magnetically positioned rigid image registration algorithm to obtain the transformation relationship between the CT image coordinate system of a movable measuring plate and the coordinate system of a magnetic field generator. It transforms the CT image coordinates of the movable measuring plate in the range measurement fixture to the spatial coordinate system of the magnetic field generator. Then, using the transformation relationship, it converts the position of the marker point on the movable measuring plate from the CT image coordinate system to the magnetic field generator coordinate system. Finally, it directly uses a magnetic sensor to obtain the position of the marker point within the range of the magnetic field generator, calculates its tracking error, and obtains the tracking error of the magnetic field generator at that location. Therefore, this method can measure the high-precision tracking range of the magnetic field generator in electromagnetic navigation technology, providing surgeons with tracking ranges at different tracking accuracies during surgery. This allows for the selection of surgical procedures that can be performed with the required precision at different accuracies, ensuring surgical safety.

[0013] It also provides a device for measuring the effective range of a magnetic field generator, which includes: a fixed frame (1), a movable measuring plate (2), a support column (3), a magnetic field generator positioning slot (4), and a slot (5);

[0014] The fixed frame is supported by four support columns. There is a magnetic field generator positioning groove at the bottom center of the fixed frame. Several serrations are set in the middle and upper parts of each support column. The movable measuring plate is placed in the four serrations of equal height and fixed by the slot.

[0015] The movable measuring plate has 8*8 conical holes symmetrically distributed at the four corners of its surface, and 1*8 conical holes symmetrically distributed at the top, bottom, horizontal and vertical of the center of the movable measuring plate, for a total of 289 conical holes. The depth of the conical holes on the movable measuring plate is 1mm, and the distance between adjacent conical holes is 1cm. Attached Figure Description

[0016] Figure 1 This is a flowchart of a method for measuring the effective range of a magnetic field generator according to the present invention.

[0017] Figure 2 This is a flowchart of step (3) according to the present invention.

[0018] Figure 3 This is a schematic diagram of the device for measuring the effective range of a magnetic field generator according to the present invention.

[0019] Figure 4 It shows Figure 3 The specific structure of the movable measuring plate.

[0020] Figure 5 It shows Figure 4 The movable measuring plate can be used in different situations. Detailed Implementation

[0021] like Figure 1 As shown, this method for measuring the effective range of a magnetic field generator includes the following steps:

[0022] (1) Install the magnetic field generator into the positioning slot of the magnetic field generator of the range measurement working device;

[0023] (2) Install a movable measuring plate to measure the spatial position of the magnetic field as needed;

[0024] (3) Use the magnetic positioning rigid image registration module to convert the CT images of the movable measuring plate into the magnetic field space coordinate system;

[0025] (4) Use the error calculation module to calculate the tracking error of each marker point. If the spatial position of the magnetic field space to be measured is not completed, move the position of the movable measuring plate and repeat steps (2)-(4). If all the magnetic field spaces to be measured are completed, execute step (5).

[0026] (5) Output the range that meets the tracking error requirements.

[0027] This invention utilizes a magnetically positioned rigid image registration algorithm to obtain the transformation relationship between the CT image coordinate system of a movable measuring plate and the coordinate system of a magnetic field generator. It transforms the CT image coordinates of the movable measuring plate in the range measurement fixture to the spatial coordinate system of the magnetic field generator. Then, using the transformation relationship, it converts the position of the marker point on the movable measuring plate from the CT image coordinate system to the magnetic field generator coordinate system. Finally, it directly uses a magnetic sensor to obtain the position of the marker point within the range of the magnetic field generator, calculates its tracking error, and obtains the tracking error of the magnetic field generator at that location. Therefore, this method can measure the high-precision tracking range of the magnetic field generator in electromagnetic navigation technology, providing surgeons with tracking ranges at different tracking accuracies during surgery. This allows for the selection of surgical procedures that can be performed with the required precision at different accuracies, ensuring surgical safety.

[0028] Preferably, such as Figure 2 As shown, step (3) includes the following sub-steps:

[0029] (3.1) Magnetic positioning mark calibration;

[0030] (3.2) Search and record the coordinates of the small steel ball in the CT image of the movable measuring plate;

[0031] (3.3) Calculate the transformation relationship between the CT image coordinate system and the magnetic field generator coordinate system using the coordinate positions of the small steel ball in the CT image coordinate system and the coordinate positions of the magnetic field generator.

[0032] Preferably, such as Figure 2 As shown, step (3.1) includes the following sub-steps:

[0033] (3.1.1) Import the 3D model of the magnetic positioning marker and obtain the positional relationship between the magnetic sensor and the magnetic positioning marker model;

[0034] (3.1.2) Install a magnetic sensor on the magnetic positioning marker;

[0035] (3.1.3) Obtain the conversion relationship between the magnetic positioning tag and the magnetic sensor;

[0036] (3.1.4) Install a sensor on the magnetic positioning mark affixed to the movable measuring plate and use the conversion relationship to obtain the position of the small steel ball under the magnetic field generator.

[0037] Preferably, when measuring a range where the tracking accuracy of a magnetic field generator is less than 3 mm, the following steps are included:

[0038] (I) Fix the magnetic field generator in the bottom positioning groove 4 of the working range measuring fixture. Fix the four corners of the movable measuring plate to the serrations of the support column 3. At this time, the center of the bottom surface of the fixed frame 1, the center of the magnetic field generator, and the center of the movable measuring plate 2 are on the same straight line. The connecting line between the center of the movable measuring plate and the center of the magnetic field generator passes through the center of the working range of the magnetic field generator (e.g., Figure 3 (as shown)

[0039] (II) Mark points a1~a5, b1~b5, and c1~c5 on the movable measuring plate. The distance between points a1-a2, a2-a3, a3-a4, and a4-a1 on the movable measuring plate is 30cm; the distance between points b1-b2, b2-b3, b3-b4, and b4-b1 is 28cm; and the distance between points c1-c2, c2-c3, c3-c4, and c4-c1 is 20cm. (e.g.) Figure 5 (As shown)

[0040] (III) Place the movable measuring plate in the sawtooth of the measuring fixture frame in the direction indicated by the red arrow, according to the near-plane installation diagram, and fix it with two slots. The bottom of the conical hole on the movable measuring plate is 5 cm above the electromagnetic tracker.

[0041] (IV) Attach magnetic positioning stickers to the movable measuring plate and scan the CT image of the movable measuring plate with magnetic positioning stickers;

[0042] (V) Place the magnetic positioning tracking sensor into the magnetic positioning marker, import the movable measuring plate image and the magnetic positioning marker model, and use the magnetic positioning rigid image registration module to obtain the transformation relationship between the movable measuring plate CT image coordinate system and the magnetic field generator coordinate system.

[0043] (VI) Using the measurement accuracy module, convert the a1~a5, b1~b5, and c1~c5 markers on the imported movable measuring plate image to the recorded coordinates in the magnetic field generator coordinate system. , , Then, the coordinates of the marker point in the coordinate system of the magnetic field generator are directly obtained using a magnetic positioning tracker. ( , , Calculate the error value between the two. , The calculation formula is:

[0044] ;

[0045] like If the value is less than 3mm, the point is considered to meet the accuracy requirements in the coordinate system of the magnetic field generator. All the marker points are measured in sequence, and all the points that meet the accuracy requirements are recorded. Then the effective tracking range at 5cm in the near plane is measured.

[0046] (VII) Change the height of the plane to be measured to 11cm, and repeat steps (V) and (VI) to measure all points that meet the accuracy requirements under the 11cm height plane; after the measurement is completed, continue to change the plane until all points within the measurement range are measured, and finally connect the areas represented by all the points to obtain the effective range of the magnetic field generator with a tracking error accuracy of less than 3mm.

[0047] like Figure 3 , 4 As shown, a device for measuring the effective range of a magnetic field generator is also provided, which includes: a fixed frame 1, a movable measuring plate 2, a support column 3, a magnetic field generator positioning slot 4, and a slot 5.

[0048] The fixed frame is supported by four support columns. There is a magnetic field generator positioning groove at the bottom center of the fixed frame. Several serrations are set in the middle and upper parts of each support column. The movable measuring plate is placed in the four serrations of equal height and fixed by the slot.

[0049] The movable measuring plate has 8*8 conical holes symmetrically distributed at the four corners of its surface, and 1*8 conical holes symmetrically distributed at the top, bottom, horizontal and vertical of the center of the movable measuring plate, for a total of 289 conical holes. The depth of the conical holes on the movable measuring plate is 1mm, and the distance between adjacent conical holes is 1cm.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for measuring the effective range of a magnetic field generator, characterized in that: It includes the following steps: (1) Install the magnetic field generator into the positioning slot of the magnetic field generator of the range measurement working device; (2) Install a movable measuring plate to measure the spatial position of the magnetic field as needed; (3) Use the magnetic positioning rigid image registration module to convert the CT images of the movable measuring plate into the magnetic field space coordinate system; (4) Use the error calculation module to calculate the tracking error of each marker point. If the spatial position of the magnetic field space to be measured is not completed, move the position of the movable measuring plate and repeat steps (2)-(4). If all the magnetic field spaces to be measured are completed, execute step (5). (5) Output the range that meets the tracking error requirements; Step (3) includes the following sub-steps: (3.1) Magnetic positioning mark calibration; (3.2) Search and record the coordinates of the small steel ball in the CT image of the movable measuring plate; (3.3) Calculate the transformation relationship from the CT image coordinate system to the magnetic field generator coordinate system using the coordinate positions of the small steel ball in the CT image coordinate system and the coordinate position in the magnetic field generator coordinate system; Step (3.1) includes the following sub-steps: (3.1.1) Import the 3D model of the magnetic positioning marker and obtain the positional relationship between the magnetic sensor and the magnetic positioning marker model; (3.1.2) Install a magnetic sensor on the magnetic positioning marker; (3.1.3) Obtain the conversion relationship between the magnetic positioning tag and the magnetic sensor; (3.1.4) Install a sensor on the magnetic positioning mark affixed to the movable measuring plate, and use the conversion relationship to obtain the position of the small steel ball under the magnetic field generator; When measuring a magnetic field generator with a tracking accuracy of less than 3 mm, the following steps are included: (I) Fix the magnetic field generator in the bottom positioning groove (4) of the working range measuring fixture, and fix the four corners of the movable measuring plate on the saw teeth of the support column (3). At this time, the center of the bottom surface of the fixed frame (1), the center of the magnetic field generator, and the center of the movable measuring plate (2) are on the same straight line, and the connecting line between the center of the movable measuring plate and the center of the magnetic field generator passes through the center of the working range of the magnetic field generator. (II) Mark points a1~a5, b1~b5, and c1~c5 on the movable measuring plate respectively. The distance between the marks a1-a2, a2-a3, a3-a4, and a4-a1 on the movable measuring plate is 30cm, the distance between the marks b1-b2, b2-b3, b3-b4, and b4-b1 is 28cm, and the distance between the marks c1-c2, c2-c3, c3-c4, and c4-c1 is 20cm. (III) Place the movable measuring plate in the sawtooth of the measuring fixture frame in the direction indicated by the red arrow, according to the near-plane installation diagram, and fix it with two slots. The bottom of the conical hole on the movable measuring plate is 5cm above the electromagnetic tracker. (IV) Attach magnetic positioning stickers to the movable measuring plate and scan the CT image of the movable measuring plate with magnetic positioning stickers; (V) Place the magnetic positioning tracking sensor into the magnetic positioning marker, import the movable measuring plate image and the magnetic positioning marker model, and use the magnetic positioning rigid image registration module to obtain the transformation relationship between the movable measuring plate CT image coordinate system and the magnetic field generator coordinate system. (VI) Using the measurement accuracy module, convert the a1~a5, b1~b5, and c1~c5 markers on the imported movable measuring plate image to the recorded coordinates in the magnetic field generator coordinate system. , , Then, the coordinates of the marker point in the coordinate system of the magnetic field generator are directly obtained using a magnetic positioning tracker. ( , , ), calculate the error value between the two. , The calculation formula is: ； like If the value is less than 3mm, the point is considered to meet the accuracy requirements in the coordinate system of the magnetic field generator. All the marker points are measured in sequence, and all the points that meet the accuracy requirements are recorded. Then the effective tracking range within 5cm in the near plane is measured. (VII) Change the height of the plane to be measured to 11cm, and repeat steps (V) and (VI) to measure all points that meet the accuracy requirements under the 11cm height plane; after the measurement is completed, continue to change the plane until all points within the measurement range are measured, and finally connect the areas represented by all the points to obtain the effective range of the magnetic field generator with a tracking error accuracy of less than 3mm.

2. The apparatus for measuring the effective range of a magnetic field generator according to claim 1, characterized in that: It includes: Fixed frame (1), movable measuring plate (2), support column (3), magnetic field generator positioning slot (4), card slot (5); The fixed frame is supported by four support columns. There is a magnetic field generator positioning groove at the bottom center of the fixed frame. Several serrations are set in the middle and upper parts of each support column. The movable measuring plate is placed in the four serrations of equal height and fixed by the slot. The movable measuring plate has 8*8 conical holes symmetrically distributed at the four corners of its surface, and 1*8 conical holes symmetrically distributed at the top, bottom, horizontal and vertical of the center of the movable measuring plate, for a total of 289 conical holes. The depth of the conical holes on the movable measuring plate is 1mm, and the distance between adjacent conical holes is 1cm.

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