Magnetic resonance imaging-guided surgery positioning device and positioning method based on radio frequency coil

Abstract

The application discloses a nuclear magnetic image guided surgery positioning device based on a radio frequency coil and a positioning method, the device comprising a solid block, a plurality of recesses are arranged on three adjacent surfaces of the solid block respectively; a glass tube filled with contrast agent is arranged in each recess, and a radio frequency coil is wound on the glass tube. The positioning method comprises the following steps: acquiring a nuclear magnetic image of the device; solving an image coordinate of a contrast agent mark mass center point; establishing a device coordinate system, solving a coordinate of the mass center point in the device coordinate system according to the arrangement of the glass tube, and obtaining a translation matrix R and a translation matrix t of the device coordinate system relative to the image coordinate system; since a surgery instrument is rigidly connected with the device, a space conversion matrix of a surgery instrument coordinate system and the image coordinate system is obtained according to the R and the t; since a coordinate of a tip point of the instrument in the instrument coordinate system is known, the real position of the tip point of the instrument in the nuclear magnetic image coordinate system is calculated based on the space conversion matrix. The application has the advantages of accurate positioning, high robustness and the like.

Description

TECHNICAL FIELD

[0001] The present application mainly relates to the technical field of medical auxiliary equipment, and particularly relates to a nuclear magnetic image guided surgical positioning device based on a radio frequency coil and a positioning method. BACKGROUND

[0002] Surgical intervention is the main means for 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 non-radiation characteristics. Among various medical imaging methods, nuclear 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 various applications such as neurosurgery puncture, cardiovascular surgery and prostate biopsy. Nuclear magnetic image guided robot-assisted interventional surgery relies on nuclear magnetic imaging equipment to guide the movement of the robot during the operation to achieve precise positioning and navigation of the surgical instrument in the operation, ensuring that it can safely and accurately reach the lesion target point of the patient, while minimizing surgical trauma and successfully completing the operation.

[0003] In the navigation process of the surgical instrument, it is necessary to first determine the conversion relationship between the surgical instrument space coordinate system and the image space coordinate system, and to obtain the position coordinates of the surgical instrument in the nuclear magnetic image space in real time, so as to accurately control the interventional process. However, calculating the conversion relationship between the coordinate systems requires selecting a suitable common reference point and simultaneously determining 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, causing image distortion in the surgical instrument area and causing difficulties in detection and positioning. The commonly used solution is to rigidly connect the surgical instrument with the positioning frame, taking the frame coordinate system as the reference, and indirectly realizing the registration of the surgical instrument space coordinate system and the image space coordinate system by registering the frame coordinate system and the nuclear magnetic image coordinate system, and completing the positioning of the surgical instrument by means of the marker points on the frame during the operation.

[0004] The existing Brown-Roberts-Wells positioning frame can only provide three effective reference mark points, and the spatial conversion relationship between the image coordinate system and the frame coordinate system is solved by solving the three-dimensional coordinate values of the three mark points in the image coordinate system and the frame coordinate system respectively. As long as the coordinate value of one point is not accurate, the solving error of the spatial conversion matrix between the two coordinate systems will be extremely large. In addition, since the mark on the existing positioning frame has poor clarity and low brightness contrast with the background area, it is difficult to be stably detected, thereby easily leading to inaccurate positioning of the surgical instrument in the operation. Therefore, it is urgent to design a new positioning frame to solve the problems of large practical application error and low robustness caused by the insufficient three-dimensional mark points and the low clarity of the traditional Brown-Roberts-Wells positioning frame, realize accurate registration of the spatial coordinate system of the surgical instrument and the nuclear magnetic image spatial coordinate system, and accurate positioning of the surgical instrument in the operation. SUMMARY

[0005] In view of the technical problems of the prior art, the present application provides a nuclear magnetic image guided surgery positioning device based on a radio frequency coil and a positioning method.

[0006] To solve the above technical problems, the technical scheme provided by the present application is as follows:

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

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

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

[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 oppositely arranged.

[0012] The present application also discloses a positioning method based on the nuclear magnetic image guided surgery positioning device based on a radio frequency coil as described above, comprising the following steps:

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

[0014] S2, solve the image coordinates of the marked centroid points, and group and sort all the marked centroid points according to the coordinates, so that the centroid points on the same plane of the solid block are grouped into the same group, and a plurality of sets of centroid point sets are obtained;

[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 the centroid points in each set of centroid point sets in the image coordinate system and the position distribution geometry of the glass tube in the solid block;

[0016] S4, obtaining the 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, obtaining 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, obtaining the space conversion 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 obtaining the space conversion matrix of the surgical instrument space coordinate system and the image space coordinate system according to the conversion relationship between the surgical instrument coordinate system and the positioning device coordinate system;

[0019] S7, selecting a mark of one of the glass tubes as a reference mark point, determining 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 calculating the real position of the tip point of the surgical instrument in the nuclear magnetic image space coordinate system based on the space conversion matrix of 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 nuclear magnetic image.

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

[0021] In step S4, 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 according to the coordinates of the preset centroid point in the positioning device coordinate system and the image coordinate system, 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] Where 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 centroid points in the two coordinate systems, fitting is respectively performed through the least square method, the plane equations of the planes where the preset centroid points are located in the two coordinate systems are respectively obtained, 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; the cross product of the unit normal vectors n and n1 is calculated to obtain the rotation axis vector u of the two coordinate systems.

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

[0028] The specific process of step S5 is as follows:

[0029] The coordinates of the preset centroid points in the image coordinate system are averaged to obtain a point P I The coordinates of the preset centroid points in the positioning device coordinate system are averaged to obtain a point P c , and the translation matrix t of the positioning device coordinate system relative to the image coordinate system is calculated based on the translation matrix R: t = P I -R·P c .

[0030] Compared with the prior art, the advantages of the present application are as follows:

[0031] The positioning device and the matching positioning method based on the radio frequency coil of the nuclear magnetic image guided surgery of the present application are suitable for the field of minimally invasive interventional surgery such as nuclear magnetic image guided robot assisted neurosurgery puncture ablation treatment or prostate biopsy sampling. The positioning device solves the problem of positioning the surgical instrument in the nuclear magnetic image guided robot assisted interventional surgery. The positioning device has simple design and high algorithm robustness, and only needs to collect a single image slice for analysis and calculation to assist in realizing the registration of the spatial coordinate system of the surgical instrument and the nuclear magnetic image spatial coordinate system and the positioning of the surgical instrument. The system of the present application can provide more effective three-dimensional marker points compared with the traditional Brown-Roberts-Wells framework. In addition, due to the enhancement of the marker signal by the radio frequency coil, the marker is easy to detect, so it has stronger algorithm robustness, improves the accuracy of surgical positioning, and is more suitable for application in high-precision medical surgery scenes such as neurosurgery puncture and prostate biopsy. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a structural schematic view of the positioning device in the embodiment of the present application.

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

[0034] Figure 3Figure 1 is a perspective view of the positioning device and puncture needle assembly of the present application; Figure 2 is a front view of the positioning device and puncture needle assembly of the present application; Figure 3 is a side view of the positioning device and puncture needle assembly of the present application; Figure 4 is a top view of the positioning device and puncture needle assembly of the present application; Figure 5 is a rear view of the positioning device and puncture needle assembly of the present application; and Figure 6 is a simplified schematic diagram of the single-plane pattern obtained by imaging the glass tube in the positioning device of the present application.

[0035] Figure 4 Figure 6 is a simplified schematic diagram of the single-plane pattern obtained by imaging the glass tube in the positioning device of the present application.

[0036] Figure 5 Figure 7 is a schematic diagram of the principle of solving the three-dimensional spatial coordinates of the marker points in the coordinate system of the positioning device and the image coordinate system of the present application.

[0037] Figure 6 Figure 8 is a schematic diagram of the thirteen elliptical markers presented by the positioning device of the present application under the nuclear magnetic image.

[0038] Figure 7 Figure 9 is a general flowchart of the intraoperative surgical instrument positioning method of the present application.

[0039] Figure 1 is a perspective view of the positioning device and puncture needle assembly of the present application; Figure 2 is a front view of the positioning device and puncture needle assembly of the present application; Figure 3 is a side view of the positioning device and puncture needle assembly of the present application; Figure 4 is a top view of the positioning device and puncture needle assembly of the present application; Figure 5 is a rear view of the positioning device and puncture needle assembly of the present application; and Figure 6 is a simplified schematic diagram of the single-plane pattern obtained by imaging the glass tube in the positioning device of the present application. DETAILED DESCRIPTION

[0040] The present application will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] As shown in Figure 1 , the nuclear magnetic image guided surgical positioning device based on a radio frequency coil provided by the embodiment of the present application comprises a cubic solid block 1, and a plurality of recesses 2 are arranged on at least three surfaces of the solid block 1; a glass tube 3 filled with contrast agent is mounted in each recess 2, and a radio frequency coil is wound around the glass tube 3. The radio frequency coil comprises an inductor 4 composed of multiple turns of annularly wound insulated copper wires 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 circular arc recesses 2 are arranged on three adjacent surfaces of the cubic solid block 1, and a glass tube 3 wound with a radio frequency coil is fixed in each recess 2. The glass tube 3 is filled with contrast agent, and the glass tube 3 wound with the radio frequency coil will present as an elliptical marker with high brightness on the nuclear magnetic image. The contrast agent is a 5% copper sulfate solution, which is convenient for clear imaging under the nuclear magnetic image. The radio frequency coil is tuned to the corresponding Larmor frequency f L of the nuclear magnetic scanner, which can further enhance the imaging signal of the contrast agent.

[0043] As shown in Figure 7As shown, the embodiment of the present application also discloses a matching positioning method of the nuclear magnetic image guided surgical positioning device based on the radio frequency coil. According to the position distribution of the elliptical mark points under the nuclear magnetic image, the spatial conversion matrix between the surgical instrument spatial coordinate system and the image spatial coordinate system is solved, and then the positioning of the surgical instrument is realized. The specific steps of the positioning method are as follows:

[0044] S1, using the nuclear magnetic imaging equipment to scan the positioning device to obtain a plurality of two-dimensional nuclear magnetic slice images, from which the image containing 13 high-intensity elliptical marks is selected for subsequent calculation.

[0045] S2, the image processing algorithm is used to solve the image coordinates of the 13 elliptical mark centroid points, and the 13 centroid points are grouped and sorted according to the coordinates. The five points obtained by imaging the five columnar tunnels belonging to the same plane in the cubic solid block 1 are divided into the same group, so that three groups of centroid point sets can be obtained.

[0046] S3, the positioning device coordinate system is established according to the actual three-dimensional size information of the positioning device. Then, according to the position of the five points in each centroid point set in the image coordinate system and the position distribution geometry of the glass tube 3 in the positioning device, the three-dimensional spatial coordinates of the three points in the positioning device coordinate system can be solved. Since there are 3 groups of point sets, the coordinates of 9 centroid points in the image coordinate system and the positioning device coordinate system can be determined at the same time. The 9 points are taken as the common reference points of the two coordinate systems, and the conversion relationship between the two coordinate systems is solved.

[0047] S4, according to the coordinates of the 9 reference points in the two coordinate systems, the least square method is used to fit respectively, and the plane equations of the reference points in the two coordinate systems are obtained respectively. 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] Further, the cross product of the two unit normal vectors is calculated to obtain 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 is calculated through the vector inner product and the inverse cosine formula:

[0049] θ=arccos(n·n1)

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

[0051]

[0052] S5, average the coordinates of the 9 reference points in the image coordinate system to obtain point P I Similarly, average the coordinates of the 9 reference points in the positioning device coordinate system to obtain point P c Therefore, 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 known parameter, so the spatial transformation matrix of the surgical instrument space coordinate system and the image space coordinate system can be indirectly obtained, and the registration of the two coordinate systems can be realized.

[0055] S7, select one of the 13 elliptical markers of the positioning device as a reference marker point for tracking the position of the surgical instrument. The coordinates of the marker point in the image coordinate system have been obtained in step two. Since the surgical instrument and the positioning device are rigidly connected, the relative position of the reference marker point and the tip point of the surgical instrument in the surgical instrument space coordinate system can be determined, and the real position of the tip point of the surgical instrument in the magnetic resonance image space coordinate system can be calculated according to the spatial transformation matrix of the surgical instrument space coordinate system and the image space coordinate system obtained in step six, so as to realize the positioning of the surgical instrument in the magnetic resonance image.

[0056] The positioning device for surgical positioning based on the radio frequency coil of the magnetic resonance image and the matching positioning method thereof are suitable for the field of minimally invasive interventional surgery such as robot-assisted neurosurgical puncture ablation treatment or prostate biopsy sampling guided by the magnetic resonance image. The positioning device solves the problem of positioning the surgical instrument in the robot-assisted interventional surgery guided by the magnetic resonance image. The positioning device has a simple design and high algorithm robustness, and only one image slice needs to be collected for analysis and calculation, so as to assist in realizing the registration of the surgical instrument space coordinate system and the magnetic resonance image space coordinate system and the positioning of the surgical instrument. The system disclosed in the present application can provide more effective three-dimensional marker points compared with the traditional Brown-Roberts-Wells frame. In addition, due to the enhancement of the marker signal by the radio frequency coil, the marker is easy to detect, so the algorithm robustness is stronger, the surgical positioning accuracy is improved, and the positioning device is more suitable for application in the high-precision medical surgery scene such as neurosurgical puncture and prostate biopsy.

[0057] In order to better understand the above technical solutions, the above technical solutions will be described in detail in combination with the drawings in the specification and specific embodiments.

[0058] AsFigure 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 aligning 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 MRI imaging.

[0061] The RF coils include an inductor 4 consisting 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 MRI 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 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 tubes 3 in the grooves 2 is as follows: Figure 4 The geometric pattern shown.

[0064] like Figure 7 As shown, based on 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 a circular needle holder 7, and the needle is placed in 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, as shown in FIG. Figure 6 shown.

[0066] The image processing algorithm is used to solve the image coordinates of the 13 elliptical mark centroids, and the 13 centroid points are sorted into groups according to the coordinates; the 5 points obtained by imaging the 5 glass tubes 3 belonging to the same plane in the cubic solid block 1 are divided into the same group, so that three groups of centroid point sets can be obtained. Since the three faces of the cubic solid block 1 are adjacent to each other, two glass tubes 3 are shared by adjacent faces, and therefore the corresponding centroid points are also shared reference points of adjacent point sets, which are repeatedly used by adjacent point sets.

[0067] The image processing algorithm mentioned above includes operations such as dilation, threshold segmentation, and centroid extraction, which can all be realized 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, and the positioning device coordinate system is established. As shown in Figure 5 According to the image coordinates of the five points in each group of centroid points and the geometric relationship of the pattern shown in Figure 4 , the three-dimensional space coordinates of the middle three points in the positioning device coordinate system are solved.

[0069] Specifically, the case where the nuclear magnetic imaging plane 8 intersects with one plane of the positioning device is as shown in Figure 5 The calculation method of the other two planes is exactly the same. When two planes intersect, five intersection points P1, P2, P3, P4, and P5 are generated, which form a point set, and the five points should be on a straight line. A first auxiliary line 9 parallel to the line segment AP1 is drawn from the B point, and the intersection point of the first auxiliary line 9 and the line segment P1P5 is P6. Similarly, a second auxiliary line 10 parallel to the line segment AP1 is also drawn from the C point, and the intersection point of the second auxiliary line 10 and the line segment P1P5 is P7. Since the coordinates of P1 and P5 under the image are both known, and the pattern on a plane is also known, the coordinates of the two trisection points P6 and P7 of the line segment P1P5 under the image can be obtained. Since the coordinates of P2, P3, and P4 under the image are also known, the lengths of the line segments P1P2, P2P6, P3P6, P3P7, P4P7, and P4P5 can be obtained, respectively. Since the triangles AP1P2 and BP2P6, BP3P6 and CP3P7, CP4P7 and DP4P5 respectively form three groups of similar triangles. Therefore, the following proportional relationships are satisfied:

[0070]

[0071] Since the length L of the cube solid block 1 is known, the values of d1, d2 and d3 can be obtained. According to the 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 the three sets of point sets, the coordinates of the nine reference points in the image coordinate system and the positioning device coordinate system can be calculated respectively.

[0072] According to the coordinates of the nine reference points in the two coordinate systems, the plane equations of the reference points in the two coordinate systems are obtained by fitting through the least square method respectively. 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] Further, the cross product of the two unit normal vectors is calculated to obtain 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 is calculated through the vector inner product and the inverse cosine formula:

[0074] θ = arccos(n · n1) (5)

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

[0076]

[0077] The coordinates of the nine reference points in the image coordinate system are averaged to obtain the point P I . Similarly, the coordinates of the nine reference points in the positioning device coordinate system are averaged to obtain the point P c , and thus 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 known parameter, so the spatial transformation matrix of the puncture needle 6 coordinate system and the image space coordinate system can be indirectly obtained.

[0080] In the 13 oval markers of the positioning device, one is selected as a reference marker point for tracking the position of the needle, and the coordinates of the marker point in the image coordinate system are known. Since the needle is rigidly connected to the device, the relative position of the reference marker 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 magnetic resonance image space coordinate system is calculated according to the obtained space conversion matrix of the puncture needle 6 space coordinate system and the image space coordinate system, so as to realize the positioning of the needle in the magnetic resonance image.

[0081] The above is only the preferred embodiment of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall be considered as falling within the protection scope of the present application.

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 a contrast agent is installed in each of the grooves (2), and a radio frequency coil is wound around the glass tube (3); The positioning process includes: S1, obtaining a two-dimensional nuclear magnetic slice image of the positioning device; the two-dimensional nuclear magnetic slice image includes the marks produced by the contrast agents of all glass tubes (3) under the nuclear magnetic image; S2, solve the image coordinates of the marked centroid points, and group and sort all the marked centroid points according to the coordinates, and group the centroid points on the same plane of the solid block (1) into the same group to obtain multiple centroid point sets; S3, establishing a positioning device coordinate system based on 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 based on 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. According to the coordinates of the preset centroid point in the positioning device coordinate system and the image coordinate system, obtain the translation matrix of the positioning device coordinate system relative to the image coordinate system R ; S5, based on the coordinates of the preset centroid point in the positioning device coordinate system and the image coordinate system and the translation matrix R， Get the translation matrix of the positioning device coordinate system relative to the image coordinate system t ; S6. According to the rotation matrix R and translation matrices t Get the spatial transformation matrix of the positioning device coordinate system relative to the image coordinate system T , and then according to the conversion relationship between the surgical instrument coordinate system and the positioning device coordinate system, the spatial conversion matrix between the surgical instrument space coordinate system and the image space coordinate system is obtained; S7, select the mark of one of the glass tubes (3) as the reference mark point, determine the relative position of the reference mark point and the surgical instrument tip point in the surgical instrument space coordinate system, and then calculate the real position of the surgical instrument tip point in the nuclear magnetic image space coordinate system based on the spatial 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 image.

2. The MRI-guided surgical 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 surgical 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 surgical 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. The MRI-guided surgical positioning device based on radio frequency coil according to claim 1, characterized in that: In step S4, the rotation axis vectors of the two coordinate systems are obtained according to the coordinates of the preset centroid point in the positioning device coordinate system and the image coordinate system. u , and the two coordinate systems' rotation axis vectors u Rotation angle , and then obtain the translation matrix of the positioning device coordinate system relative to the image coordinate system R。 6. The MRI-guided surgical positioning device based on radio frequency coil according to claim 5, characterized in that: The translation matrix R The calculation formula is: The rotation axis vector u =( u x , u y , u z ).

7. The MRI-guided surgical positioning device based on radio frequency coil according to claim 5 or 6, characterized in that: Get the rotation axis vector of the two coordinate systems u The specific process is: According to the coordinates of the preset centroid in the two coordinate systems, the plane equations of the plane where the preset centroid is located in the two coordinate systems are obtained respectively by fitting through the least square method. The unit normal vector of the plane in the positioning device coordinate system is calculated according to the two plane equations. n and the unit normal vector of the plane in the image coordinate system n 1; Then calculate the unit normal vector n and n 1 cross product to obtain the rotation axis vector of the two coordinate systems u .

8. The MRI-guided surgical positioning device based on radio frequency coil according to claim 7, characterized in that: Rotation angle The calculation formula is: 。 9. The MRI-guided surgical positioning device based on radio frequency coil according to claim 1, 5 or 6, characterized in that: The specific process of step S5 is: The average coordinates of the preset centroid point in the image coordinate system are obtained P I ; Take the average of the coordinates of the preset centroid point in the positioning device coordinate system to get the point P c , then based on the translation matrix R Calculate the translation matrix of the positioning device coordinate system relative to the image coordinate system t : .

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