A registration method based on rib curvature changes

Abstract

The present invention discloses a registration method based on rib curvature change, comprising: step 1, ultrasonic probe coordinate acquisition, using the position information of the end joint of the mechanical arm to obtain the coordinates of the ultrasonic probe in the mechanical arm coordinate system in real time; step 2, curvature change measurement, in the process of the ultrasonic probe moving along the rib direction, through the curvature sensor or the curvature calculation module, the curvature change of the ultrasonic probe is measured in real time; step 3, rib curvature distribution function analysis, using CT imaging technology to obtain a three-dimensional model of the rib in advance, and calculating the curvature distribution function of the rib along different directions; step 4, scanning section determination, according to the measured ultrasonic probe curvature change and the rib curvature distribution function, determine the specific rib section to be scanned; step 5, coordinate system registration, using the rib section information obtained by scanning to perform registration with the rib model in the CT coordinate system, so as to achieve high-precision registration between the mechanical arm coordinate system and the CT coordinate system.

Description

Technical Field

[0001] The invention relates to the field of registration, and in particular to a registration method based on rib curvature changes. Background Art

[0002] In medical imaging detection, ultrasound technology has been widely used as a radiation-free and highly real-time imaging acquisition method.

[0003] However, during rib scanning, positioning and navigation have always been a problem due to factors such as rib occlusion and patient breathing. Summary of the invention

[0004] Purpose of the invention: To provide a registration method based on rib curvature changes to solve the above-mentioned problems existing in the prior art.

[0005] Technical solution: A registration method based on rib curvature changes, including:

[0006] Step 1: Acquire the coordinates of the ultrasonic probe, using the position information of the end joint of the robotic arm to obtain the coordinates of the ultrasonic probe in the robotic arm coordinate system in real time;

[0007] Step 2, measuring the curvature change, in the process of the ultrasonic probe moving along the rib direction, the curvature change of the ultrasonic probe is measured in real time through a curvature sensor or a curvature calculation module;

[0008] Step 3: rib curvature distribution function analysis: using CT imaging technology to obtain a three-dimensional model of the ribs and calculate the curvature distribution functions of the ribs in different directions;

[0009] Step 4: determining the scanning section, determining the specific rib section to be scanned according to the measured curvature change of the ultrasound probe and the rib curvature distribution function;

[0010] Step 5: Coordinate system registration: use the rib segment information obtained by scanning to align with the rib model in the CT coordinate system to achieve high-precision registration between the robot arm coordinate system and the CT coordinate system.

[0011] The present invention obtains the coordinates of the ultrasound probe in the robotic arm coordinate system in real time based on the position information of the end joint of the robotic arm, measures the curvature change of the ultrasound probe when it moves along the rib direction, and obtains the curvature distribution function of the rib three-dimensional model in combination with the rib model obtained from CT segmentation in advance, thereby achieving high-precision alignment of the robotic arm coordinate system and the CT coordinate system, and then completing the scanning of the rib area. The present invention combines robotic arm navigation and rib curvature analysis to achieve precise positioning and alignment of the ultrasound probe during scanning. Compared with traditional methods, the present invention has higher scanning accuracy, real-time performance and positioning accuracy, and provides a more reliable method for medical image detection.

[0012] In a further embodiment, step 1 further comprises:

[0013] Step 11: Robot arm kinematic modeling. First, the robot arm to which this patent applies should have an accurate kinematic model. This model describes the motion rules of each joint of the robot arm. This is usually achieved through the URDF (Unified Robot Description Format) file, which contains the geometry and joint information of the robot arm. We use tools such as MoveIt of ROS (Robot Operating System) to model the kinematics of the robot arm;

[0014] Step 12: determining the installation coordinates of the ultrasonic probe, and determining the installation coordinates of the ultrasonic probe relative to the end effector of the robotic arm, which generally includes the translation and rotation information of the ultrasonic probe relative to the coordinate system of the end effector of the robotic arm;

[0015] Step 13: motion trajectory planning and control, using a motion trajectory planning and control framework, such as MoveIt, to control the motion of the robotic arm and incorporate the coordinate information of the ultrasound probe into the target position;

[0016] Step 14: coordinate transformation: transform the coordinates of the ultrasonic probe from the coordinate system of the end effector of the robotic arm to the coordinate system of the base of the robotic arm through the kinematic model of the robotic arm;

[0017] Step 15: Acquire ultrasound probe data and write ROS nodes and other control software to obtain actual data from the ultrasound probe;

[0018] Step 16: Data processing: processing the actual data obtained from the ultrasound probe to ensure that they are correctly interpreted as position information in the robot arm coordinate system;

[0019] Step 17: Real-time update: When the robotic arm moves, the coordinate information of the ultrasonic probe is updated in real time. This usually needs to be implemented in the control loop of the robotic arm.

[0020] The reason for the design of step 14 is that each axis of an N-axis robot (usually six or seven axes) has its own independent coordinate system, which makes it convenient for the robot control program to control the posture of the entire robot arm individually or jointly. If you want to know the posture of the end of the robot arm (usually relative to the world coordinate system, that is, the coordinate system of the robot arm base), you need to do a coordinate transformation. This transformation is usually calculated along the end of the robot arm toward the base axis by axis.

[0021] Here are the general steps:

[0022] Determine joint angles: Get the current angles of each joint of the robot arm.

[0023] Forward Kinematics: Use the forward kinematics equations to convert joint angles to the position and orientation of the end effector.

[0024] The forward kinematics equations are usually determined by the geometry and kinematic parameters of the robot. For a 7-axis robot, this may involve a series of rotation and translation matrices.

[0025] The posture of the robot arm is usually represented by rotation matrix, Euler angle, quaternion, etc. Choosing the appropriate representation depends on your specific needs.

[0026] Calculate attitude: Extract attitude information based on the results of the forward kinematics equation. This may include rotation matrices, Euler angles, or quaternions.

[0027] In a further embodiment, step 2 further comprises:

[0028] Step 21, calculating the curvature of the ultrasound probe, based on the obtained real-time coordinate information of the ultrasound probe, using the position information of the ultrasound probe in the rib coordinate system to calculate the curvature; the curvature is a physical quantity that describes the degree of curvature of a curve.

[0029] In a further embodiment, the step 21 further comprises:

[0030] Step 211, real-time updating, based on real-time updating of the position information of the ultrasound head and recalculating the curvature, ensuring that the measurement and calculation frequency is high enough to capture the subtle changes of the ribs;

[0031] Step 212: data recording and display, recording the curvature data measured in real time, and displaying or storing it as needed.

[0032] In a further embodiment, step 3 further comprises:

[0033] Step 31, obtaining a CT image, using a CT scanner to obtain a CT image of the ribs, ensuring that the image quality is sufficient to obtain accurate anatomical structure information;

[0034] Step 32, image segmentation, uses an image segmentation algorithm to separate the rib region in the CT image from other tissues or structures, which is achieved through image segmentation algorithms such as threshold processing and region growing. The goal is to create a binary mask representing the ribs;

[0035] Step 33: 3D reconstruction, using the segmented rib region data to perform 3D reconstruction;

[0036] Step 34, calculate the curvature of the rib area data. Once the three-dimensional reconstructed model is obtained, the curvature is calculated using a mathematical method; curvature is a physical quantity that describes the degree of curvature of a curve or surface.

[0037] In a further embodiment, step 34 comprises:

[0038] Step 341, a curvature calculation algorithm is used to calculate the curvature based on analytical calculation of differential geometry;

[0039] Step 342, curvature distribution function, the curvature distribution function includes a function that describes how the curvature changes with position; we calculate the curvature of each point.

[0040] In a further embodiment, step 4 comprises:

[0041] Step 41: Obtain the curvature distribution function in the CT coordinate system, the curvature change during real-time ultrasound scanning, and deduce the scanning position.

[0042] In a further embodiment, step 41 comprises:

[0043] Step 411, understand the curvature distribution function, which represents the change of curvature with spatial position, including a function about position, i.e., k(x, y, z), where x, y, z are the coordinates of point k in three-dimensional space;

[0044] Step 412: numerical solution, based on the numerical data of the curvature distribution function, numerical integration and numerical optimization are used to fit and calculate the scanning position.

[0045] Beneficial effect: The present invention discloses a registration method based on the change of rib curvature. The present invention obtains the coordinates of the ultrasonic probe in the robotic arm coordinate system in real time according to the position information of the end joint of the robotic arm. By measuring the curvature change of the ultrasonic probe when it moves along the rib direction, the curvature distribution function of the rib three-dimensional model is obtained by combining the rib model obtained from CT segmentation in advance, thereby realizing high-precision registration of the robotic arm coordinate system and the CT coordinate system, and then completing the scanning of the rib area. The present invention combines robotic arm navigation and rib curvature analysis to realize precise positioning and registration of the ultrasonic probe during scanning. Compared with traditional methods, the present invention has higher scanning accuracy, real-time performance and positioning accuracy, and provides a more reliable method for medical image detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic flow chart of the method of the present invention.

[0047] Figure 2 It is a specific flow diagram of step 1 of the present invention.

[0048] Figure 3 It is a specific flow diagram of step 2 of the present invention.

[0049] Figure 4 It is a specific flow diagram of step 3 of the present invention.

[0050] Figure 5It is a specific flow diagram of step 4 of the present invention. DETAILED DESCRIPTION

[0051] The present application relates to a registration method based on rib curvature changes, which is explained in detail below through a specific implementation method.

[0052] A registration method based on rib curvature change, comprising:

[0053] Step 1: Acquire the coordinates of the ultrasonic probe, using the position information of the end joint of the robotic arm to obtain the coordinates of the ultrasonic probe in the robotic arm coordinate system in real time;

[0054] Step 11: Robot arm kinematic modeling. First, the robot arm to which this patent applies should have an accurate kinematic model. This model describes the motion rules of each joint of the robot arm. This is usually achieved through the URDF (Unified Robot Description Format) file, which contains the geometry and joint information of the robot arm. We use tools such as MoveIt of ROS (Robot Operating System) to model the kinematics of the robot arm;

[0055] Step 12: determining the installation coordinates of the ultrasonic probe, and determining the installation coordinates of the ultrasonic probe relative to the end effector of the robotic arm, which generally includes the translation and rotation information of the ultrasonic probe relative to the coordinate system of the end effector of the robotic arm;

[0056] Step 13: motion trajectory planning and control, using a motion trajectory planning and control framework, such as MoveIt, to control the motion of the robotic arm and incorporate the coordinate information of the ultrasound probe into the target position;

[0057] Step 14: coordinate transformation: transform the coordinates of the ultrasonic probe from the coordinate system of the end effector of the robotic arm to the coordinate system of the base of the robotic arm through the kinematic model of the robotic arm;

[0058] Step 15: Acquire ultrasound probe data and write ROS nodes and other control software to obtain actual data from the ultrasound probe;

[0059] Step 16: Data processing: processing the actual data obtained from the ultrasound probe to ensure that they are correctly interpreted as position information in the robot arm coordinate system;

[0060] Step 17: Real-time update: When the robotic arm moves, the coordinate information of the ultrasonic probe is updated in real time. This usually needs to be implemented in the control loop of the robotic arm.

[0061] Step 2, measuring the curvature change, in the process of the ultrasonic probe moving along the rib direction, the curvature change of the ultrasonic probe is measured in real time through a curvature sensor or a curvature calculation module;

[0062] Step 21, calculating the curvature of the ultrasound probe, based on the obtained real-time coordinate information of the ultrasound probe, using the position information of the ultrasound probe in the rib coordinate system to calculate the curvature; the curvature is a physical quantity that describes the degree of curvature of a curve.

[0063] The step 21 further comprises:

[0064] Step 211, real-time updating, based on real-time updating of the position information of the ultrasound head and recalculating the curvature, ensuring that the measurement and calculation frequency is high enough to capture the subtle changes of the ribs;

[0065] Step 212: data recording and display, recording the curvature data measured in real time, and displaying or storing it as needed.

[0066] Step 3: rib curvature distribution function analysis: using CT imaging technology to obtain a three-dimensional model of the ribs and calculate the curvature distribution functions of the ribs in different directions;

[0067] Step 31, obtaining a CT image, using a CT scanner to obtain a CT image of the ribs, ensuring that the image quality is sufficient to obtain accurate anatomical structure information;

[0068] Step 32, image segmentation, uses an image segmentation algorithm to separate the rib region in the CT image from other tissues or structures, which is achieved through image segmentation algorithms such as threshold processing and region growing. The goal is to create a binary mask representing the ribs;

[0069] Step 33: 3D reconstruction, using the segmented rib region data to perform 3D reconstruction;

[0070] Step 34, calculate the curvature of the rib area data. Once the three-dimensional reconstructed model is obtained, the curvature is calculated using a mathematical method; curvature is a physical quantity that describes the degree of curvature of a curve or surface.

[0071] The step 34 comprises:

[0072] Step 341, a curvature calculation algorithm is used to calculate the curvature based on analytical calculation of differential geometry;

[0073] Step 342, curvature distribution function, the curvature distribution function includes a function that describes how the curvature changes with position; we calculate the curvature of each point.

[0074] Step 4: determining the scanning section, determining the specific rib section to be scanned according to the measured curvature change of the ultrasound probe and the rib curvature distribution function;

[0075] Step 41: Obtain the curvature distribution function in the CT coordinate system, the curvature change during real-time ultrasound scanning, and deduce the scanning position.

[0076] The step 41 comprises:

[0077] Step 411, understand the curvature distribution function, which represents the change of curvature with spatial position, including a function about position, i.e., k(x, y, z), where x, y, z are the coordinates of point k in three-dimensional space;

[0078] Step 412: numerical solution, based on the numerical data of the curvature distribution function, numerical integration and numerical optimization are used to fit and calculate the scanning position.

[0079] Step 5: Coordinate system registration: use the rib segment information obtained by scanning to align with the rib model in the CT coordinate system to achieve high-precision registration between the robot arm coordinate system and the CT coordinate system.

[0080] The present invention obtains the coordinates of the ultrasound probe in the robotic arm coordinate system in real time based on the position information of the end joint of the robotic arm, measures the curvature change of the ultrasound probe when it moves along the rib direction, and obtains the curvature distribution function of the rib three-dimensional model in combination with the rib model obtained from CT segmentation in advance, thereby achieving high-precision alignment of the robotic arm coordinate system and the CT coordinate system, and then completing the scanning of the rib area. The present invention combines robotic arm navigation and rib curvature analysis to achieve precise positioning and alignment of the ultrasound probe during scanning. Compared with traditional methods, the present invention has higher scanning accuracy, real-time performance and positioning accuracy, and provides a more reliable method for medical image detection.

[0081] Working principle description:

[0082] Ultrasonic probe coordinate acquisition: using the position information of the end joint of the robotic arm, the coordinates of the ultrasonic probe in the robotic arm coordinate system are acquired in real time;

[0083] Curvature change measurement: when the ultrasound probe moves along the rib direction, the curvature change of the ultrasound probe is measured in real time through a curvature sensor or a curvature calculation module;

[0084] Analysis of rib curvature distribution function: using CT imaging technology to obtain a three-dimensional model of the ribs and calculate the curvature distribution function of the ribs in different directions;

[0085] Scanning section determination: determining the specific rib section to be scanned according to the measured curvature change of the ultrasound probe and the rib curvature distribution function;

[0086] Coordinate system registration uses the rib segment information obtained by scanning to align with the rib model in the CT coordinate system to achieve high-precision registration between the robot arm coordinate system and the CT coordinate system.

[0087] The preferred specific embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above specific embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical scheme of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A registration method based on rib curvature change, characterized in that: include: Step 1: Acquire the coordinates of the ultrasonic probe, using the position information of the end joint of the robotic arm to obtain the coordinates of the ultrasonic probe in the robotic arm coordinate system in real time; Step 1 includes: Step 11: Kinematic modeling of the robotic arm: Use the MoveIt tool of ROS to perform kinematic modeling of the robotic arm; Step 12: Determine the installation coordinates of the ultrasonic probe, and determine the installation coordinates of the ultrasonic probe relative to the end effector of the robotic arm, including the translation and rotation information of the ultrasonic probe relative to the coordinate system of the end effector of the robotic arm; Step 13: motion trajectory planning and control, controlling the motion of the robotic arm, and incorporating the coordinate information of the ultrasound probe into the target position; Step 14: coordinate transformation: transform the coordinates of the ultrasound probe from the end coordinate system of the robotic arm to the robotic arm coordinate system through the kinematic model of the robotic arm; Step 15: Acquire ultrasound probe data, write a ROS node, and obtain the actual data of the ultrasound probe; Step 16: Data processing: processing the actual data obtained from the ultrasound probe to ensure that they are correctly interpreted as position information in the robot arm coordinate system; Step 17: Real-time update: when the robotic arm moves, the coordinate information of the ultrasonic probe is updated in real time; Step 2, measuring the curvature change, in the process of the ultrasonic probe moving along the rib direction, the curvature change of the ultrasonic probe is measured in real time by using the curvature sensor; Step 2 includes: Step 21, calculating the curvature of the ultrasound probe, according to the obtained real-time coordinate information of the ultrasound probe, using the position information of the ultrasound probe in the rib coordinate system to calculate the curvature; Step 3: rib curvature distribution function analysis: using CT images to obtain a three-dimensional model of the ribs and calculate the curvature distribution functions of the ribs along different directions; Step 3 includes: Step 31, obtaining a CT image, using a CT scanner to obtain a CT image of the ribs; Step 32, image segmentation, using an image segmentation algorithm to separate the rib region in the CT image from other tissues or structures, and create a binary mask representing the rib; Step 33: 3D reconstruction, using the segmented rib region data to perform 3D reconstruction; Step 34, calculating the curvature of the rib area data, obtaining a three-dimensional reconstruction model, and calculating the curvature; Step 4: determining the scanning section, determining the specific rib section to be scanned according to the measured curvature change of the ultrasound probe and the rib curvature distribution function; Step 5: Coordinate system registration: use the rib segment information obtained by scanning to align with the rib model in the CT coordinate system to achieve high-precision registration between the robot arm coordinate system and the CT coordinate system.

2. The registration method based on rib curvature change according to claim 1, characterized in that: The step 21 comprises: Step 211, real-time updating, based on real-time updating of the position information of the ultrasound probe and recalculating the curvature, ensuring that the measurement and calculation frequency is high enough to capture the subtle changes of the ribs; Step 212: data recording and display, recording the curvature data measured in real time, and displaying or storing it as needed.

3. The registration method based on rib curvature change according to claim 1, characterized in that: The step 4 comprises: Step 41: Obtain the curvature distribution function in the CT coordinate system and the real-time ultrasonic scanning curvature change, and deduce the scanning position.

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