Optical scanning-based magnetocardiogram registration system and method

Abstract

The application provides a magnetocardiogram registration system and method based on optical scanning, and the system comprises a bed body registration module and a CT image registration module. The bed body registration module comprises a first arc-shaped marker and an L-shaped base, and the CT image registration module comprises a second arc-shaped marker which is consistent in shape with the first arc-shaped marker of the bed body registration module. Both the bed body registration module and the CT image registration module are made of non-magnetic photosensitive resin material. Before magnetocardiogram (MCG) acquisition, the two registration modules are digitized by using a handheld optical scanner. According to the bed body registration module, the sensor array coordinate system and the human body coordinate system are aligned. When CT scanning is performed, the image structure of the trunk part of a subject is obtained. According to the CT image registration module, the human body coordinate system and the CT coordinate system are aligned. Correspondingly, the application also provides a registration method corresponding to the system, which significantly improves the efficiency and accuracy of the MCG registration process and promotes the subsequent medical research and application of MCG.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biomedical engineering, and particularly relates to a magnetocardiogram registration system and method based on optical scanning. BACKGROUND

[0002] Magnetocardiogram (MCG) is a non-contact functional imaging technology, which studies the heart activity state by measuring the electrophysiological information generated by the heart activity, and has the advantages of non-invasiveness, non-radiation, high sensitivity, strong specificity, etc. Clinical studies have shown that MCG has important clinical application value in the early diagnosis of myocardial ischemia, fetal heart disease, arrhythmia and other diseases.

[0003] MCG three-dimensional imaging is an important MCG analysis method, which fuses MCG information with human structure image information through registration, reconstructs the electrophysiological activity of the heart, accurately locates the lesion point, and is used for subsequent clinical diagnosis and analysis.

[0004] The widely used registration method at present is to use a sensor position indicator (SPI) based on an electromagnetic digitizer (Polhemus, Colchester, VT) to complete the digitization of the human body trunk markers and the sensor array, so as to realize the alignment of the sensor array and the human image structure. Although the electromagnetic digitizer has high theoretical accuracy, in actual use, the calibration of the positioning coil, the accuracy of the prior information such as position and direction, the proficiency of the operator, etc. will all affect the positioning accuracy, and the entire digitization process is very time-consuming. Reducing the errors introduced by the registration digitization process, improving the registration accuracy and efficiency to realize higher source positioning accuracy and repeatability is an urgent technical problem to be solved in the field of MCG imaging. SUMMARY

[0005] In order to overcome the shortcomings of the existing method, the present application provides a magnetocardiogram registration system and method based on optical scanning, which quickly and accurately completes the magnetocardiogram registration process.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] A magnetocardiogram registration system based on optical scanning, comprising a bed body registration module and a CT image registration module, the bed body registration module comprising a first arc-shaped marker and a cylindrical + hemispherical marker located above the first arc-shaped marker, the first arc-shaped marker having an L-shaped base on both sides, and the CT image registration module comprising a second arc-shaped marker and a cylindrical + hemispherical marker located above the second arc-shaped marker, the bed body registration module and the CT image registration module both being non-magnetic photosensitive resin materials.

[0008] Further, the MCG imaging device comprises a magnetic shielding barrel, a bed body, an MCG atomic magnetometer array panel, an atomic magnetometer and an MCG imaging device upper computer system, the MCG atomic magnetometer array panel is adjusted in height by the MCG imaging device upper computer system, and the bed body can place a bed body registration module.

[0009] Further, the handheld optical scanner and the upper computer system are included, and before MCG acquisition, the CT image registration module is placed on the side of the body of the subject, so that the influence of respiratory motion is reduced. The bed body registration module and the CT image registration module are manually scanned.

[0010] Further, the CT scanning device is included, and when CT scanning is performed, the CT image registration module information needs to be acquired.

[0011] Further, the bed body registration module and the CT image registration module are registered by principal component analysis (PCA-ICP) and iterative closest point method.

[0012] The application also provides a magnetocardiogram registration method, comprising the following steps:

[0013] Step 1: the subject lies on the bed body, and a bed body registration module is arranged at a fixed position of the bed body;

[0014] Step 2: according to the waist circumference size of the subject, CT image registration modules are arranged at appropriate positions on both sides of the body of the subject, so that they are closely attached to the human body;

[0015] Step 3: start the handheld optical scanner, quickly complete the scanning of the bed body registration module and the CT image registration module, and process and encapsulate the scanning data through the upper computer system, and save as a scanning point cloud data file;

[0016] Step 4: the subject is sent into the magnetic shielding barrel, and the MCG imaging device upper computer system is used to control the MCG atomic magnetometer array panel to be lifted to the height of the human body and record the height as H;

[0017] Step 5: the MCG imaging device starts to acquire MCG signals and saves them as Basedate files;

[0018] Step 6: after the magnetocardiogram signal acquisition is completed, the subject wears the CT image registration module to perform CT image scanning, obtains the human body structure image, saves it as a DICOM file, and performs segmentation and three-dimensional reconstruction on the CT image to obtain a CT three-dimensional reconstruction model;

[0019] Step 7: the bed body registration module point cloud is extracted from the scanning point cloud data file, the bed body registration module point cloud is registered with the bed body registration module model in the MCG imaging device through the PCA-ICP algorithm, and a conversion matrix T1 is obtained;

[0020] Step 8: Extract the CT image registration module point cloud from the scanning point cloud data file, and register the CT image registration module point cloud with the CT image registration module model obtained from the CT three-dimensional reconstruction model through the PCA-ICP algorithm to obtain a conversion matrix T2;

[0021] Step 9: The position and direction of the sensors on the MCG atomic magnetometer array panel relative to the position and direction of the MCG imaging device are known during the device design process. The height H and the conversion matrix T=T2*T1 are applied to the position and direction of the sensors, respectively, to finally obtain the position and direction of the sensors relative to the CT image.

[0022] Further, in step 7, the bed body registration module point cloud and the bed body registration module model in the MCG imaging device are coarsely registered through the PCA algorithm. The specific method is as follows: for the bed body registration module with a known position in the MCG imaging device model, a coordinate system P1-U1V1W1 is established with the center of the first arc-shaped marker as the origin. PCA analysis is performed on the first arc-shaped marker contour to obtain three characteristic vectors The corresponding eigenvalues are λ1>λ2>λ3, corresponding to the P1U1 direction, corresponding to the P1V1 direction, corresponding to the P1W1 direction, and the P1U1, P1V1, and P1W1 directions are the directions of the three principal components, respectively. For the bed body registration module point cloud, a coordinate system P2-U2V2W2 is established with the center of the first arc-shaped marker as the origin. The X-axis direction of the bed body registration module point cloud is consistent with the P2U2 direction, the Y-axis direction is consistent with the P2V2 direction, and the Z-axis direction is consistent with the P2W2 direction. The coordinate systems P1-U1V1W1 and P2-U2V2W2 are registered as the coarse registration result of the bed body registration module point cloud and the bed body registration module model in the MCG imaging device, and then the ICP algorithm is used for fine registration.

[0023] Further, in step 8, the CT image registration module point cloud is extracted from the scanning point cloud data, and the CT image registration module point cloud is coarsely registered with the CT image registration module model obtained from the CT three-dimensional reconstruction model through the PCA algorithm. The specific method is as follows: for the CT image registration module point cloud, a coordinate system Q1-U1′V1′W1′ is established with the center of the second arc-shaped marker as the origin. PCA analysis is performed on the second arc-shaped marker contour to obtain three characteristic vectors The corresponding eigenvalues are λ1′>λ2′>λ3′, corresponding to the Q1U1′ direction, corresponding to the Q1V1′ direction, Corresponding to the Q1W1′ direction, the Q1U1′, Q1V1′, and Q1W1′ directions are the directions of the three principal components, respectively. For the CT image registration module model, a coordinate system Q2-U2′V2′W2′ is established with the center of the second arc-shaped marker as the origin. The X-axis of the CT is consistent with Q2W2′, the Y-axis of the CT is consistent with Q2U2′, and the Z-axis of the CT is consistent with Q2V2′. The coordinate systems Q1-U1′V1′W1′ and Q2-U2′V2′W2′ are registered as coarse registration results between the scanned point cloud data and the CT image, and then the ICP algorithm is used for fine registration.

[0024] The advantages of this invention over existing technologies are:

[0025] This invention develops two detachable registration modules. The registration modules are digitized using a handheld optical scanner, and the operation process is simple and easy to learn. Automatic registration is completed through the PCA-ICP algorithm, which greatly improves the registration accuracy and efficiency, and promotes the subsequent medical research and application of MCG. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a magnetocardiogram registration system based on optical scanning according to the present invention;

[0027] Figure 2 This is a flowchart of a magnetocardiogram registration method based on optical scanning according to the present invention;

[0028] Figure 3 This is a schematic diagram of the bed registration module structure of a magnetocardiogram registration system based on optical scanning according to the present invention; (a) is a schematic diagram of coordinate system P1-U1V1W1, and (b) is a schematic diagram of coordinate system P2-U2V2W2.

[0029] Figure 4 This is a schematic diagram of the CT image registration module of a magnetocardiogram registration system based on optical scanning according to the present invention; (a) is a schematic diagram of coordinate system Q1-U1′V1′W1′, and (b) is a schematic diagram of coordinate system Q2-U2′V2′W2′.

[0030] Figure 5 This is a schematic diagram of the central magnetic map registration result of the present invention;

[0031] Figure reference numerals: 1-Magnetic shielding cylinder; 2-Bed body; 3-MCG atomic magnetometer array panel; 4-Atomic magnetometer; 5-Bed body registration module; 6-CT image registration module; 7-MCG imaging equipment host computer system; 8-Handheld optical scanner. Detailed Implementation

[0032] The present invention will now be described in more detail with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0033] Example 1

[0034] like Figure 1 As shown, this invention discloses a magnetocardiogram (MCG) registration system based on optical scanning, comprising a bed registration module 5 and a CT image registration module 6. The bed registration module has a first arc-shaped marker with L-shaped bases perpendicular to the bed on both sides and four sets of non-coplanar cylindrical and spherical markers on top. The CT image registration module has two second arc-shaped markers, distributed on both sides of the body to account for respiratory effects. The markers on the second arc-shaped markers of the CT image registration module are consistent with the markers on the first arc-shaped markers of the bed registration module. The modular design allows the bed registration module to be detached from the bed, making it suitable for each subject. This invention uses a handheld optical scanner 8 to accurately position the bed registration module, obtaining the relative positional relationship between the scanned point cloud and the MCG atomic magnetometer array panel 3. Then, the CT image registration module point cloud extracted from the scanned point cloud is used for registration with the CT image registration module model in the CT 3D reconstruction model, improving registration accuracy and laying the foundation for high-precision MCG imaging.

[0035] The bed registration module is made of non-magnetic photosensitive resin material. The first arc-shaped marker has an arc length of 120mm, a width of 60mm, and a thickness of 2mm. The L-shaped base has a length of 15mm, a width of 60mm, and a height of 20mm. The cylindrical marker base has a diameter of 10mm and a height of 15mm. The spherical marker has a radius of 3mm.

[0036] The CT image registration module is made of the same material as the bed registration module, and the second arc-shaped marker and the cylindrical + spherical marker above it are exactly the same size as the cylindrical + spherical marker on the bed registration module. The CT image registration module is acquired during CT scanning. Since the density of the CT image registration module differs from that of human tissue, it can be easily extracted during CT 3D reconstruction.

[0037] The MCG imaging device includes a magnetic shielding container 1, a bed, an MCG atomic magnetometer array panel 3, an atomic magnetometer, and an MCG imaging device host computer system 7. The magnetic shielding container 1 provides an extremely weak magnetic field measurement environment. The atomic magnetometer 4 is inserted into and fixed in the MCG atomic magnetometer array panel 3. The MCG imaging device host computer system 7 controls and adjusts the height of the array panel from the human body. Registration markers are placed at a fixed position on the bed 2.

[0038] The optical scanning-based MCG registration system comprises a handheld optical scanner 8, a CT detection device, CT image registration modules arranged on both sides of the body of the subject before MCG acquisition, the handheld optical scanner is used to scan the bed body registration module and the CT image registration module, the position of the bed body registration module and the position of the CT image registration module are quickly obtained, and the registration time is shortened.

[0039] The bed body registration module point cloud obtained from the scanning point cloud data and the bed body registration module model in the MCG imaging device model, and the CT image registration module point cloud obtained from the scanning point cloud data and the CT image registration module model in the CT three-dimensional reconstruction model are automatically registered by the principal component analysis method and the iterative nearest neighbor point method (PCA-ICP), so that the registration efficiency is improved.

[0040] Embodiment two

[0041] As shown in Figure 2 The optical scanning-based MCG registration system is used for registration, and the specific implementation comprises the following steps:

[0042] Step 1: The subject lies flat on the bed body, and a bed body registration module is arranged at a fixed position of the bed body;

[0043] Step 2: According to the waist circumference size of the subject, CT image registration modules are arranged at appropriate positions on both sides of the body of the subject, so as to be closely attached to the human body;

[0044] Step 3: The handheld optical scanner is started, the bed body registration module and the CT image registration module are quickly scanned, and the scanning data is processed and packaged by the upper computer system, and saved as a point cloud data file;

[0045] Step 4: The subject is sent into the magnetic shielding cylinder, and the MCG imaging device upper computer system is used to control the MCG atomic magnetometer array panel to be lifted to the height of the human body and record the height as H;

[0046] Step 5: The MCG imaging device starts to acquire MCG signals and saves them as Basedate files;

[0047] Step 6: After the acquisition of the magnetocardiogram signals is completed, the subject wears the CT image registration module to perform CT image scanning, obtains the human body structure image, and saves it as a DICOM file. The CT image is segmented and three-dimensionally reconstructed to obtain a CT three-dimensional reconstruction model;

[0048] Step 7: The bed body registration module point cloud is extracted from the scanning point cloud data file, the bed body registration module point cloud is registered with the bed body registration module model in the MCG imaging device by the PCA-ICP algorithm, and a conversion matrix T1 is obtained;

[0049] Step 7.1: Manually extract the bed body registration module point cloud from the scanned point cloud data file;

[0050] Step 7.2: Bed body registration module registration. For the bed body registration module model in the MCG imaging device model, establish a coordinate system P1-U1V1W1( Figure 3 (a)) with the first arc-shaped marker center as the origin, perform PCA analysis on the first arc-shaped marker contour to obtain three eigenvectors The corresponding eigenvalues are λ1> λ2> λ3, Corresponding to P1U1 direction, Corresponding to P1V1 direction, Corresponding to P1W1 direction, P1U1, P1V1, P1W1 directions are the directions of the three principal components respectively; for the bed body registration module point cloud, establish a coordinate system P2-U2V2W2( Figure 3 (b)) with the first arc-shaped marker center as the origin, the X-axis direction of the bed body registration module point cloud is consistent with P2U2, the Y-axis direction is consistent with P2V2, and the Z-axis direction is consistent with P2W2; register the two coordinate systems as the coarse registration result of the bed body registration module point cloud and the bed body registration module model in the MCG imaging device;

[0051] Step 7.3: Fine registration using ICP algorithm to obtain conversion matrix T1;

[0052] Step 8: Extract the CT image registration module point cloud from the scanned point cloud data file, and register the CT registration module point cloud and the CT image registration module model obtained from the CT three-dimensional reconstruction model through the PCA-ICP algorithm to obtain the conversion matrix T2;

[0053] Step 8.1: Manually extract the CT image registration module point cloud from the scanned point cloud data file;

[0054] Step 8.2: CT image registration module registration. For the CT image registration module point cloud, establish a coordinate system Q1-U1′V1′W1′( Figure 4 (a)) with the second arc-shaped marker center as the origin, perform PCA analysis on the second arc-shaped marker contour to obtain three eigenvectors The corresponding eigenvalues are λ1′> λ2′> λ3′, Corresponding to Q1U1′ direction, Corresponding to Q1V1′ direction, Corresponding to Q1W1′ direction, Q1U1′, Q1V1′, Q1W1′ directions are the directions of the three principal components respectively; for the CT image registration module model, establish Q2-U2′V2′W2′( Figure 4(b)), the X-axis direction of CT is consistent with Q2W2', the Y-axis of CT is consistent with Q2U2', and the Z-axis of CT is consistent with Q2V2'; the coordinate system Q1-U1'V1'W1' and the coordinate system Q2-U2'V2'W2' are registered, as a coarse registration result of the scanning point cloud data and the CT image;

[0055] Step 8.3: fine registration is performed using the ICP algorithm to obtain a conversion matrix T2;

[0056] Step 9: the height H and the conversion matrix T=T2xT1 are applied to the MCG atomic magnetometer array panel.

[0057] The purpose of the magnetocardiogram registration is to obtain the position and direction of the sensor relative to the CT. Since the position and direction of the sensor on the sensor array panel in the MCG imaging device are known in the device design process, the registration process is to convert the MCG system coordinate system in which the sensor array panel is located to the CT coordinate system. Figure 5 The final registration result is shown, and the arrow indicates the direction of the sensor, and the prototype indicates the coordinates of the sensor, both of which have been converted to the CT coordinate system.

[0058] The contents not described in detail in the specification of the present application belong to the prior art known to those skilled in the art.

[0059] The above embodiments are provided only for the purpose of describing the present application, and are not intended to limit the scope of the present application. The scope of the present application is defined by the appended claims. The present application should also include modifications and variations of the present application within the scope of the claims of the present application and equivalent technologies, provided that the modifications and variations of the present application belong to the scope of the claims of the present application and equivalent technologies.

Claims

1. A magnetocardiogram registration system based on optical scanning, characterized in that, Includes a bed registration module and a CT image registration module; The bed registration module includes a first arc-shaped marker and two L-shaped bases on both sides. A cylindrical and hemispherical marker is provided above the first arc-shaped marker. The CT image registration module includes a second arc-shaped marker, which is identical in shape to the first arc-shaped marker of the bed registration module, and the second arc-shaped marker is also provided with a cylindrical + hemispherical marker on top. Both the bed registration module and the CT image registration module are made of non-magnetic photosensitive resin material; The system also includes a handheld optical scanner, used to scan the bed registration module and the CT image registration module respectively before MCG acquisition, and generate scan point cloud data; The point cloud of the bed registration module is extracted from the scanned point cloud data file. The point cloud of the bed registration module is then registered with the bed registration module model in the MCG imaging equipment using the PCA-ICP algorithm to obtain the transformation matrix. ; The CT image registration module point cloud is extracted from the scanned point cloud data file. The CT registration module point cloud is then registered with the CT image registration module model obtained from the CT 3D reconstruction model using the PCA-ICP algorithm to obtain the transformation matrix. ; The position and orientation of the sensors on the MCG atomic magnetometer array panel relative to the MCG imaging device were known during the device design process. Height was applied to the position and orientation of the sensors respectively. and transformation matrix This allows us to obtain the position and orientation of the sensor relative to the CT image.

2. The magnetocardiogram registration system based on optical scanning according to claim 1, characterized in that, It also includes an MCG imaging device, which includes a magnetic shielding barrel, a bed, an MCG atomic magnetometer array panel, an atomic magnetometer, and an MCG imaging device host computer system. The height of the MCG atomic magnetometer array panel is adjusted through the MCG imaging device host computer system.

3. The magnetocardiogram registration system based on optical scanning according to claim 1, characterized in that, Before MCG acquisition, a CT image registration module is placed on the side of the subject's body, and a bed registration module is placed on the bed. The bed registration module and the CT image registration module are then manually scanned using a handheld optical scanner.

4. The magnetocardiogram registration system based on optical scanning according to claim 1, characterized in that, It also includes a CT scanning device, which performs CT scanning to acquire CT image registration module structural information.

5. A magnetocardiogram registration method based on optical scanning, applied to the registration system described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1: The subject lies flat on the bed, and the bed registration module is placed at a fixed position on the bed; Step 2: Based on the subject's waist circumference, place the CT image registration module at appropriate positions on both sides of the subject's body to ensure close contact with the body. Step 3: Start the handheld optical scanner to quickly complete the scanning of the bed registration module and CT image registration module, and process and encapsulate the scan data through the host computer system, saving it as a scan point cloud data file; Step 4: Place the subject inside the magnetic shielding cylinder. Use the MCG imaging equipment's host computer system to control the MCG atomic magnetometer array panel to rise and fall to a suitable height for the human body and record the height. ; Step 5: The MCG imaging device acquires the MCG signal and saves it as a Basedate file; Step 6: After the acquisition of the magnetic field signal is completed, the subject wears a CT image registration module to perform a CT image scan, obtain human structure images, save them as DICOM files, segment and reconstruct the CT images to obtain a CT 3D reconstruction model. Step 7: Extract the bed registration module point cloud from the scanned point cloud data file, and register the bed registration module point cloud with the bed registration module model in the MCG imaging equipment using the PCA-ICP algorithm to obtain the transformation matrix. ; Step 8: Extract the CT image registration module point cloud from the scanned point cloud data file, and register the CT registration module point cloud with the CT image registration module model obtained from the CT 3D reconstruction model using the PCA-ICP algorithm to obtain the transformation matrix. ; Step 9: The position and orientation of the sensors on the MCG atomic magnetometer array panel relative to the MCG imaging device are known during the device design process. The position and orientation of the sensors are then determined by applying height... and transformation matrix Ultimately, the position and orientation of the sensor relative to the CT image are obtained.

6. The magnetocardiogram registration method according to claim 5, characterized in that, In step 7, the point cloud of the bed registration module and the bed registration module model in the MCG imaging device are coarsely registered using the PCA algorithm. Specifically, for the bed registration module model with a known position in the MCG imaging device model, a coordinate system is established with the center of the first arc-shaped marker as the origin. PCA analysis was performed on the contour of the first arc-shaped marker to obtain three eigenvectors. , , The corresponding eigenvalue is , Corresponding to direction, Corresponding to direction, Corresponding to direction, , The directions are the directions of the three principal components; for the point cloud of the bed registration module, a coordinate system is established with the center of the first arc-shaped marker as the origin. The X-axis direction of the point cloud of the bed registration module is in relation to... Consistent with the Y-axis direction Consistent with the Z-axis direction Consistent; coordinate system With coordinate system Registration is performed to obtain the coarse registration result between the point cloud of the bed registration module and the model of the bed registration module in the MCG imaging device, and then the ICP algorithm is used for fine registration.

7. The magnetocardiogram registration method according to claim 5, characterized in that, In step 8, the CT image registration module point cloud is extracted from the scanned point cloud data. The CT image registration module point cloud is then coarsely registered with the CT image registration module model obtained from the CT 3D reconstruction model using the PCA algorithm. Specifically, for the CT image registration module point cloud, a coordinate system is established with the center of the second arc-shaped marker as the origin. PCA analysis was performed on the contour of the second arc-shaped marker to obtain three eigenvectors. , , The corresponding eigenvalues ​​are , Corresponding to direction, Corresponding to direction, Corresponding to direction, , The directions are the directions of the three principal components; for the CT image registration module model, a coordinate system is established with the center of the second arc-shaped marker as the origin. The X-axis direction of CT is... Consistent, the Y-axis of CT is the same as Consistent, the Z-axis of CT is the same as Consistent; coordinate system and coordinate system Registration is performed as a coarse registration result between the scanned point cloud data and the CT image, and then the ICP algorithm is used for fine registration.

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