Nuclear magnetic image guided operation positioning device and method based on radio frequency coil

Abstract

The invention discloses a nuclear magnetic image guided operation positioning device and method based on a radio frequency coil, and the device comprises a solid block, and three adjacent surfaces of the solid block are respectively provided with a plurality of grooves; a glass tube filled with a contrast agent is mounted in each groove, and a radio frequency coil is wound on each tube. The positioning method comprises the following steps: acquiring a nuclear magnetic image of the device; solving the image coordinates of the contrast agent marked centroid point; establishing a device coordinate system, solving coordinates of the centroid point in the device coordinate system according to the arrangement of the glass tubes, and obtaining a translation matrix R and a translation matrix t of the device coordinate system relative to an image coordinate system; the surgical instrument is rigidly connected with the device, so that a spatial transformation matrix of a surgical instrument coordinate system and an image coordinate system is obtained according to R and t; because the coordinate of the instrument tip point in the instrument coordinate system is known, the real position of the instrument tip point in the nuclear magnetic image coordinate system is calculated based on the space transformation matrix. The method has the advantages of accurate positioning, high robustness and the like.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of medical auxiliary equipment, and in particular to a nuclear magnetic resonance imaging-guided surgery positioning device and positioning method based on a radio frequency coil. Background Art

[0002] Surgical intervention is the main means of treating these diseases. In recent years, with the maturity of medical imaging equipment and imaging technology, image-guided robot-assisted surgery has been widely used to improve the clinical effect of interventional surgery due to its high efficiency, minimally invasive and radiation-free characteristics. Among various medical imaging methods, magnetic resonance imaging provides higher quality soft tissue contrast and does not expose patients to ionizing radiation, making it an increasingly attractive option for guiding robot-assisted applications such as neurosurgical puncture, cardiovascular surgery and prostate biopsy. Magnetic resonance imaging-guided robot-assisted interventional surgery relies on magnetic resonance imaging equipment to guide the robot's movements during the operation to achieve accurate positioning and navigation of surgical instruments during the operation, ensuring that they can safely and accurately reach the patient's lesion target, while minimizing surgical trauma and successfully completing the operation.

[0003] In the process of surgical instrument navigation, it is first necessary to determine the conversion relationship between the surgical instrument space coordinate system and the image space coordinate system, and obtain the position coordinates of the surgical instrument in the nuclear magnetic image space in real time, so as to accurately control the intervention process. However, to calculate the conversion relationship between the coordinate systems, it is necessary to select a suitable common reference point and simultaneously determine its spatial position in the two coordinate systems. However, most of the existing interventional surgical instruments are made of metal, which will introduce metal artifacts in the nuclear magnetic image, resulting in image distortion in the surgical instrument area, making detection and positioning difficult. The current commonly used solution is to rigidly connect the surgical instrument to the positioning frame, use the frame coordinate system as a reference, and indirectly realize the alignment of the surgical instrument space coordinate system and the image space coordinate system by aligning the frame coordinate system with the nuclear magnetic image coordinate system, and use the marking points on the frame to complete the positioning of the surgical instrument during the operation.

[0004] The existing Brown-Roberts-Wells positioning framework can only provide three valid reference marking points. The spatial transformation relationship between the two coordinate systems is solved by solving the three-dimensional coordinate values ​​of the three marking points in the image coordinate system and the frame coordinate system. As long as the coordinate value of one point is calculated inaccurately, the error in solving the spatial transformation matrix between the two coordinate systems will be extremely large. In addition, due to the poor clarity of the markings on the existing positioning framework and the low brightness contrast with the background area, it is difficult to be stably detected, which can easily lead to inaccurate positioning of surgical instruments during surgery. Therefore, it is urgent to design a new positioning framework to solve the problems of large practical application errors and low robustness caused by insufficient three-dimensional marking points and low clarity in the traditional Brown-Roberts-Wells positioning framework, so as to achieve accurate alignment of the spatial coordinate system of surgical instruments with the spatial coordinate system of nuclear magnetic resonance images, as well as precise positioning of surgical instruments during surgery. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the present invention provides a nuclear magnetic imaging guided surgery positioning device and positioning method based on a radio frequency coil with precise positioning.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0007] A nuclear magnetic image-guided surgical positioning device based on a radio frequency coil comprises a solid block, at least three surfaces of which are provided with a plurality of grooves; a glass tube filled with a contrast agent is installed in each of the grooves, and a radio frequency coil is wound around the glass tube.

[0008] As a further improvement of the above technical solution:

[0009] The radio frequency coil includes an inductor composed of multiple turns of annularly wound insulated copper wire and a ceramic chip capacitor, and the inductor is connected in parallel with the capacitor.

[0010] The contrast agent is a 5% copper sulfate solution.

[0011] The solid block is a cube made of acrylic plastic, the grooves are located on three adjacent faces of the cube, and two of the faces are arranged opposite to each other.

[0012] The present invention also discloses a positioning method based on the above-mentioned nuclear magnetic imaging guided surgery positioning device based on radio frequency coil, comprising the steps of:

[0013] S1, obtaining a two-dimensional nuclear magnetic slice image of the positioning device; the two-dimensional nuclear magnetic slice image includes marks generated by contrast agents in all glass tubes under the nuclear magnetic image;

[0014] S2, solving the image coordinates of the marked centroid points, and grouping and sorting all the marked centroid points according to the coordinates, dividing the centroid points on the same plane of the solid block into the same group, and obtaining multiple groups of centroid point sets;

[0015] S3, establishing a positioning device coordinate system according to the actual three-dimensional size information of the solid block, and then solving the three-dimensional space coordinates of the preset centroid point in the positioning device coordinate system according to the positions of all centroid points in each group of centroid points in the image coordinate system and the geometric relationship of the position distribution of the glass tube in the solid block;

[0016] S4. Obtain a translation matrix R of the positioning device coordinate system relative to the image coordinate system according to the coordinates of the preset centroid point in the positioning device coordinate system and the image coordinate system;

[0017] S5. Obtain the translation matrix t of the positioning device coordinate system relative to the image coordinate system according to the coordinates of the preset centroid point in the positioning device coordinate system and the image coordinate system and the translation matrix R;

[0018] S6. Obtain the spatial transformation matrix T of the positioning device coordinate system relative to the image coordinate system according to the rotation matrix R and the translation matrix t, and then obtain the spatial transformation matrix between the surgical instrument space coordinate system and the image space coordinate system according to the transformation relationship between the surgical instrument coordinate system and the positioning device coordinate system;

[0019] S7. Select the mark of one of the glass tubes as the reference mark point, determine the relative position of the reference mark point and the tip point of the surgical instrument in the surgical instrument space coordinate system, and then calculate the real position of the tip point of the surgical instrument in the magnetic resonance imaging space coordinate system based on the space transformation matrix between the surgical instrument space coordinate system and the image space coordinate system in step S6 to realize the positioning of the surgical instrument under the magnetic resonance imaging.

[0020] As a further improvement of the above technical solution:

[0021] In step S4, according to the coordinates of the preset center of mass point in the positioning device coordinate system and the image coordinate system, the rotation axis vector u of the two coordinate systems and the rotation angle of the two coordinate systems around the rotation axis vector u are obtained, and then the translation matrix R of the positioning device coordinate system relative to the image coordinate system is obtained.

[0022] The calculation formula of the translation matrix R is:

[0023]

[0024] The rotation axis vector u=(u x ,u y ,u z ).

[0025] The specific process of obtaining the rotation axis vector u of the two coordinate systems is:

[0026] According to the coordinates of the preset center of mass point in the two coordinate systems, fitting is performed respectively by the least squares method to obtain the plane equations of the plane where the preset center of mass point is located in the two coordinate systems respectively, and the unit normal vector n of the plane in the positioning device coordinate system and the unit normal vector n1 of the plane in the image coordinate system are calculated according to the two plane equations; then the rotation axis vector u of the two coordinate systems is obtained by calculating the cross product of the unit normal vectors n and n1.

[0027] The calculation formula of the rotation angle θ is: θ=arccos(n·n1).

[0028] The specific process of step S5 is:

[0029] Take the average of the coordinates of the preset centroid point in the image coordinate system to get point P I ; Take the average coordinates of the preset centroid point in the positioning device coordinate system to obtain point P c , and then calculate the translation matrix t of the positioning device coordinate system relative to the image coordinate system based on the translation matrix R: t = P I -R.P c .

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] The radio frequency coil-based nuclear magnetic imaging-guided surgical positioning device and its supporting positioning method of the present invention are suitable for the field of minimally invasive interventional surgery such as nuclear magnetic imaging-guided robot-assisted neurosurgery puncture ablation treatment or prostate biopsy sampling. The positioning device solves the problem of surgical instrument positioning in nuclear magnetic imaging-guided robot-assisted interventional surgery. The positioning device is simple in design and has high algorithm robustness. It only needs to collect a single image slice for analysis and calculation to assist in the alignment of the surgical instrument space coordinate system with the nuclear magnetic imaging space coordinate system and the positioning of the surgical instrument. The system proposed in the present invention can provide more effective three-dimensional marking points compared to the traditional Brown-Roberts-Wells framework. In addition, since the radio frequency coil enhances the marking signal, the marking is easy to detect, so it has stronger algorithm robustness, improves the surgical positioning accuracy, and is more suitable for applications in high-precision medical surgery scenarios such as neurosurgery puncture and prostate biopsy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of a positioning device in an embodiment of the present invention.

[0033] Figure 2 It is a schematic structural diagram of a positioning device and a puncture needle assembly in an embodiment of the present invention.

[0034] Figure 3The present invention is a structural diagram of the positioning device and the puncture needle assembly in an embodiment; (a) is a front view; (b) is a side view; (c) is a top view; (d) is a rear view; and (e) is a stereoscopic view.

[0035] Figure 4 It is a simplified schematic diagram of a single-sided pattern obtained by imaging the glass tube embedded in the positioning device of the present invention.

[0036] Figure 5 It is a schematic diagram of the principle of solving the three-dimensional spatial coordinates of the marker point in the positioning device coordinate system and the image coordinate system respectively in the present invention.

[0037] Figure 6 The figure is a schematic diagram of thirteen elliptical marks displayed by the positioning device of the present invention under a nuclear magnetic resonance image.

[0038] Figure 7 It is an overall flow chart of the intraoperative surgical instrument positioning method in an embodiment of the present invention.

[0039] Legend: 1. Solid block; 2. Groove; 3. Glass tube; 4. Inductor; 5. Capacitor; 6. Puncture needle; 7. Ring needle holder; 8. MRI plane; 9. First auxiliary line; 10. Second auxiliary line. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] like Figure 1 As shown, the nuclear magnetic image guided surgical positioning device based on radio frequency coil provided by the embodiment of the present invention comprises a cubic solid block 1, at least three faces of which are provided with a plurality of grooves 2; a glass tube 3 filled with contrast agent is installed in each groove 2, and a radio frequency coil is wound on the glass tube 3. The radio frequency coil comprises an inductor 4 composed of multiple turns of annularly wound insulated copper wire and a ceramic chip capacitor 5, and the inductor 4 element is connected in parallel with the capacitor 5.

[0042] Specifically, a total of 13 arc-shaped grooves 2 are provided on three adjacent surfaces of the cubic solid block 1, and a glass tube 3 wrapped with a radio frequency coil is fixed in each groove 2. The glass tube 3 is filled with contrast agent, and the glass tube 3 wrapped with the radio frequency coil will appear as a high-brightness elliptical mark on the nuclear magnetic resonance image. The contrast agent is a 5% copper sulfate solution, which facilitates clear imaging under nuclear magnetic resonance imaging. The radio frequency coil is tuned to the Larmor frequency f corresponding to the nuclear magnetic resonance scanner. L , which can further enhance the contrast agent imaging signal.

[0043] like Figure 7As shown, the embodiment of the present invention also discloses a matching positioning method for a nuclear magnetic resonance imaging guided surgical positioning device based on a radio frequency coil, which solves the spatial transformation matrix between the surgical instrument space coordinate system and the image space coordinate system according to the position distribution of the elliptical marker points under the nuclear magnetic resonance imaging, thereby realizing the positioning of the surgical instrument. The specific steps of the positioning method are as follows:

[0044] S1. Use nuclear magnetic resonance imaging equipment to scan the positioning device to obtain multiple two-dimensional nuclear magnetic resonance slice images, and select images containing 13 high-brightness elliptical marks for subsequent calculations.

[0045] S2. Use image processing algorithms to solve the image coordinates of the 13 elliptical marked centroid points respectively, and group and sort the 13 centroid points according to the coordinates. The five points obtained by imaging the five columnar tunnels belonging to the same plane in the solid cube block 1 are grouped into the same group, so that three sets of centroid point sets can be obtained.

[0046] S3. Establish the positioning device coordinate system according to the actual three-dimensional size information of the positioning device. Then, according to the positions of the five points in each group of centroid points in the image coordinate system and the geometric relationship of the position distribution of the glass tube 3 in the positioning device, the three-dimensional spatial coordinates of three of the points in the positioning device coordinate system can be solved. Since there are three groups of points in total, the coordinates of the nine centroid points in the image coordinate system and the positioning device coordinate system can be determined simultaneously. These nine points are used as the common reference points of the two known coordinate systems to solve the conversion relationship between the two coordinate systems.

[0047] S4. According to the coordinates of the 9 reference points in the two coordinate systems, the least square method is used to fit the plane equations of the planes where the reference points are located in the two coordinate systems. According to the two plane equations, the unit normal vector n of the plane in the positioning device coordinate system and the unit normal vector n1 of the plane in the image coordinate system can be calculated respectively;

[0048] Furthermore, by calculating the cross product of the two unit normal vectors, the rotation axis vector u of the two coordinate systems is obtained, and the rotation angle θ of the two coordinate systems around the rotation axis vector u is calculated by the vector inner product and the arc cosine formula:

[0049] θ=arccos(n·n1)

[0050] Using the Rodriguez formula, by rotating the axis vector u = (u x ,u y ,u z ) and the rotation angle θ to construct the rotation matrix R from the positioning device coordinate system to the image coordinate system:

[0051]

[0052] S5. Take the average coordinates of the 9 reference points in the image coordinate system to get point P I Similarly, the coordinates of the 9 reference points in the positioning device coordinate system are averaged to obtain point P c , so the translation matrix t of the positioning device coordinate system relative to the image coordinate system can be calculated:

[0053] t=P I -R.P c

[0054] S6. The spatial transformation matrix T of the positioning device coordinate system relative to the image coordinate system is composed of the rotation matrix R and the translation matrix t. Since the surgical instrument and the positioning device are rigidly connected, the transformation relationship between the surgical instrument coordinate system and the positioning device coordinate system is a pre-known parameter, so the spatial transformation matrix of the surgical instrument space coordinate system and the image space coordinate system can be indirectly obtained to achieve the registration of the two coordinate systems.

[0055] S7. Select one of the 13 elliptical marks on the positioning device as a reference mark point for tracking the position of the surgical instrument. The coordinates of the mark point in the image coordinate system have been obtained in step 2. Since the surgical instrument is rigidly connected to the positioning device, the relative position of the reference mark point and the surgical instrument tip point in the surgical instrument space coordinate system can be determined, and the real position of the surgical instrument tip point in the nuclear magnetic image space coordinate system is calculated based on the spatial transformation matrix of the surgical instrument space coordinate system and the image space coordinate system obtained in step 6, so as to realize the positioning of the surgical instrument under the nuclear magnetic image.

[0056] The radio frequency coil-based nuclear magnetic imaging-guided surgical positioning device and its supporting positioning method of the present invention are suitable for the field of minimally invasive interventional surgery such as nuclear magnetic imaging-guided robot-assisted neurosurgery puncture ablation treatment or prostate biopsy sampling. The positioning device solves the problem of surgical instrument positioning in nuclear magnetic imaging-guided robot-assisted interventional surgery. The positioning device is simple in design and has high algorithm robustness. It only needs to collect a single image slice for analysis and calculation to assist in the alignment of the surgical instrument space coordinate system with the nuclear magnetic imaging space coordinate system and the positioning of the surgical instrument. The system proposed in the present invention can provide more effective three-dimensional marking points compared to the traditional Brown-Roberts-Wells framework. In addition, since the radio frequency coil enhances the marking signal, the marking is easy to detect, so it has stronger algorithm robustness, improves the surgical positioning accuracy, and is more suitable for applications in high-precision medical surgery scenarios such as neurosurgery puncture and prostate biopsy.

[0057] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0058] like Figure 1 As shown, the embodiment of the present invention provides a novel surgical positioning device based on a radio frequency coil on the one hand, and on the other hand Figure 7 As shown, a complete set of positioning methods is also provided for efficiently and accurately registering the surgical instrument (puncture needle 6) coordinate system with the image coordinate system and realizing the positioning of the surgical instrument (puncture needle 6).

[0059] Registration is to obtain the conversion matrix between the surgical instrument coordinate system and the image coordinate system, so that the actual position of the puncture needle 6 in the image coordinate system can be indirectly obtained with the help of the marking points on the positioning device, thereby achieving accurate positioning of the puncture needle 6.

[0060] Specifically, the positioning device includes a cubic solid block 1 processed by 3D printing technology. The solid block 1 is made of acrylic plastic and has 13 arc-shaped grooves 2 on its surface. A glass tube 3 wrapped with a radio frequency coil is fixed in each groove 2. The contrast agent filled in the glass tube 3 is a 5% copper sulfate solution, which facilitates clear imaging under nuclear magnetic resonance imaging.

[0061] The RF coil includes an inductor 4 composed of multiple turns of annularly wound insulated copper wire and a ceramic chip capacitor 5. Each RF coil is tuned to the Larmor frequency f corresponding to the nuclear magnetic scanner. L , in order to enhance the contrast agent imaging signal. Assuming that the inductance of the inductor 4 is L and the capacitance of the capacitor 5 is C, the resonant frequency of the coil is:

[0062]

[0063] like Figure 3 As shown, 13 arc-shaped grooves 2 are respectively distributed on three planes of the cubic solid block 1. Specifically, two planes have two vertical grooves 2 and three inclined grooves 2, and the remaining plane has only three inclined grooves 2. The position distribution of the fixed glass tube 3 in the groove 2 is as follows: Figure 4 The geometric pattern shown.

[0064] like Figure 7 As shown, according to the image of the positioning device under the nuclear magnetic resonance imaging device, the space conversion matrix between the surgical instrument coordinate system and the image space coordinate system can be calculated, and the position of the puncture needle 6 in the image coordinate system can be obtained. The positioning method specifically includes the following steps:

[0065] First, if Figure 2 As shown, the puncture needle 6 is rigidly connected to the positioning device using the annular needle holder 7, and they are put into the nuclear magnetic resonance imaging device together to collect multiple two-dimensional slice images, and the image containing 13 high-brightness elliptical marks is selected for solution, such as Figure 6 shown.

[0066] The image processing algorithm is used to solve the image coordinates of the centroids of the 13 elliptical markers, and the 13 centroid points are grouped and sorted according to the coordinates; the five points obtained by imaging the five glass tubes 3 belonging to the same plane in the cubic solid block 1 are grouped into the same group, so that three sets of centroid point sets can be obtained. Since the three faces of the cubic solid block 1 are adjacent to each other, there are two glass tubes 3 shared by the adjacent faces, so the corresponding centroid points are also the common reference points of the adjacent point sets and are reused by the adjacent point sets.

[0067] The above-mentioned image processing algorithms include dilation operations, threshold segmentation, centroid extraction and other operations, which can all be implemented by calling functions in the Opencv library.

[0068] According to the actual three-dimensional size information of the device, the origin and three-axis directions of the positioning device coordinate system are specified to establish the positioning device coordinate system. Figure 5 As shown, the image coordinates of the five points in each group of centroid points and Figure 4 The geometric relationship of the pattern shown is used to solve the three-dimensional spatial coordinates of the three middle points in the coordinate system of the positioning device.

[0069] Specifically, the situation when the nuclear magnetic imaging plane 8 intersects with a plane of the positioning device is as follows: Figure 5 As shown, the calculation method for the other two faces is exactly the same. When two planes intersect, five intersection points will be generated, namely P1, P2, P3, P4 and P5, which form a set of points, and these five points should be on a straight line. Starting from point B, draw a first auxiliary line 9 parallel to line segment AP1, and let the intersection of the first auxiliary line 9 and line segment P1 P5 be P6. Similarly, starting from point C, draw a second auxiliary line 10 parallel to line segment AP1, and let the intersection of the second auxiliary line 10 and line segment P1 P5 be P7. Since the coordinates of P1 and P5 in the image are known, and the pattern on one face is known, the coordinate values ​​of the two trisection points P6 and P7 of line segment P1 P5 in the image can be obtained. Since the coordinates of P2, P3, and P4 in the image are also known, the lengths of line segments P1P2, P2P6, P3P6, P3P7, P4P7, and P4P5 can be obtained respectively. Since triangles AP1P2 and BP2P6, BP3P6 and CP3P7, CP4P7 and DP4P5 form three groups of similar triangles, the following proportional relationship is satisfied:

[0070]

[0071] Since the side length L of the solid cube 1 is known, the values ​​of d1, d2 and d3 can be obtained. Based on these three values, the three-dimensional coordinates of the reference points P2, P3 and P4 in the positioning device coordinate system can be easily obtained. Therefore, using three sets of points, a total of 9 reference points can be calculated in the image coordinate system and the positioning device coordinate system.

[0072] According to the coordinates of the 9 reference points in the two coordinate systems, the least squares method is used to fit the plane equations of the plane where the reference points are located in the two coordinate systems. According to the two plane equations, the unit normal vector n of the plane in the positioning device coordinate system and the unit normal vector n1 of the plane in the image coordinate system can be calculated respectively.

[0073] Furthermore, by calculating the cross product of the two unit normal vectors, the rotation axis vector u of the two coordinate systems is obtained, and the rotation angle θ of the two coordinate systems around the rotation axis vector u is calculated by the vector inner product and the arc cosine formula:

[0074] θ=arccos(n·n1) (5)

[0075] Using the Rodriguez formula, by rotating the axis vector u = (u x ,u y ,u z ) and the rotation angle θ can be constructed to obtain the rotation matrix R from the positioning device coordinate system to the image coordinate system:

[0076]

[0077] The coordinates of the 9 reference points in the image coordinate system are averaged to obtain point P I Similarly, the coordinates of the 9 reference points in the positioning device coordinate system are averaged to obtain point P c , so the translation matrix t of the positioning device coordinate system relative to the image coordinate system can be calculated:

[0078] t=P I -R.P c (7)

[0079] The spatial transformation matrix T of the positioning device coordinate system relative to the image coordinate system is composed of the rotation matrix R and the translation matrix t. Since the surgical instrument and the device are rigidly connected, the transformation relationship between the surgical instrument coordinate system and the positioning device coordinate system is a pre-known parameter, so the spatial transformation matrix between the puncture needle 6 space coordinate system and the image space coordinate system can be indirectly obtained.

[0080] One of the 13 elliptical marks on the positioning device is selected as a reference mark point for tracking the needle position, and the coordinates of the mark point in the image coordinate system are known. Since the needle is rigidly connected to the device, the relative position of the reference mark point and the puncture needle tip in the surgical instrument space coordinate system can be determined, and the real position of the puncture needle tip in the nuclear magnetic image space coordinate system is calculated based on the obtained space transformation matrix between the puncture needle space coordinate system and the image space coordinate system, so as to realize the needle positioning under the nuclear magnetic image.

[0081] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A nuclear magnetic imaging guided surgical positioning device based on radio frequency coil, characterized in that: It comprises a solid block (1), wherein at least three surfaces of the solid block (1) are provided with a plurality of grooves (2); a glass tube (3) filled with contrast agent is installed in each of the grooves (2), and a radio frequency coil is wound around the glass tube (3).

2. The MRI-guided surgery positioning device based on radio frequency coil according to claim 1, characterized in that: The radio frequency coil comprises an inductor (4) composed of multiple turns of annularly wound insulated copper wire and a ceramic chip capacitor (5), wherein the inductor (4) and the capacitor (5) are connected in parallel.

3. The MRI-guided surgery positioning device based on radio frequency coil according to claim 1, characterized in that: The contrast agent is a 5% copper sulfate solution.

4. The MRI-guided surgery positioning device based on radio frequency coil according to claim 1, 2 or 3, characterized in that: The solid block (1) is a cube made of acrylic plastic, and the grooves (2) are located on three adjacent faces of the cube, with two of the faces being arranged opposite to each other.

5. A positioning method for a nuclear magnetic image-guided surgery positioning device based on a radio frequency coil according to any one of claims 1 to 4, characterized in that: Includes steps: S1, obtaining a two-dimensional nuclear magnetic resonance slice image of the positioning device; the two-dimensional nuclear magnetic resonance slice image includes the marks produced by the contrast agent of all glass tubes (3) under the nuclear magnetic resonance image; S2, solving the image coordinates of the marked centroid points, and grouping and sorting all the marked centroid points according to the coordinates, dividing the centroid points in the same plane of the solid block (1) into the same group, and obtaining multiple groups of centroid point sets; S3, establishing a positioning device coordinate system according to the actual three-dimensional size information of the solid block (1), and then solving the three-dimensional space coordinates of the preset centroid point in the positioning device coordinate system according to the positions of all centroid points in each group of centroid points in the image coordinate system and the position distribution geometric relationship of the glass tube (3) in the solid block (1); S4. Obtain a translation matrix R of the positioning device coordinate system relative to the image coordinate system according to the coordinates of the preset centroid point in the positioning device coordinate system and the image coordinate system; S5. Obtain the translation matrix t of the positioning device coordinate system relative to the image coordinate system according to the coordinates of the preset centroid point in the positioning device coordinate system and the image coordinate system and the translation matrix R; S6. Obtain the spatial transformation matrix T of the positioning device coordinate system relative to the image coordinate system according to the rotation matrix R and the translation matrix t, and then obtain the spatial transformation matrix between the surgical instrument space coordinate system and the image space coordinate system according to the transformation relationship between the surgical instrument coordinate system and the positioning device coordinate system; S7. Select the mark of one of the glass tubes (3) as a reference mark point, determine the relative position of the reference mark point and the tip point of the surgical instrument in the surgical instrument space coordinate system, and then calculate the real position of the tip point of the surgical instrument in the nuclear magnetic resonance image space coordinate system based on the space transformation matrix between the surgical instrument space coordinate system and the image space coordinate system in step S6, so as to realize the positioning of the surgical instrument under the nuclear magnetic resonance image.

6. The positioning method according to claim 5, characterized in that: In step S4, according to the coordinates of the preset center of mass point in the positioning device coordinate system and the image coordinate system, the rotation axis vector u of the two coordinate systems and the rotation angle θ of the two coordinate systems around the rotation axis vector u are obtained, and then the translation matrix R of the positioning device coordinate system relative to the image coordinate system is obtained.

7. The positioning method according to claim 6, characterized in that: The calculation formula of the translation matrix R is: The rotation axis vector u=(u x ,u y ,u z ).

8. The positioning method according to claim 6 or 7, characterized in that: The specific process of obtaining the rotation axis vector u of the two coordinate systems is: According to the coordinates of the preset center of mass point in the two coordinate systems, fitting is performed respectively by the least squares method to obtain the plane equations of the plane where the preset center of mass point is located in the two coordinate systems respectively, and the unit normal vector n of the plane in the positioning device coordinate system and the unit normal vector n1 of the plane in the image coordinate system are calculated according to the two plane equations; then the rotation axis vector u of the two coordinate systems is obtained by calculating the cross product of the unit normal vectors n and n1.

9. The positioning method according to claim 8, characterized in that: The calculation formula of the rotation angle θ is: θ=arccos(n·n1).

10. The positioning method according to claim 5, 6 or 7, characterized in that: The specific process of step S5 is: Take the average of the coordinates of the preset centroid point in the image coordinate system to get point P I ; Take the average coordinates of the preset centroid point in the positioning device coordinate system to obtain point P c , and then calculate the translation matrix t of the positioning device coordinate system relative to the image coordinate system based on the translation matrix R: t = P I -R.P c .

Images