Dynamic calibration device and method for isocenter of radiotherapy mechanical arm

Abstract

The application relates to a radiotherapy mechanical arm isocenter dynamic calibration device and method, the calibration device comprises a six-axis collaborative mechanical arm, an exposure device and a control unit; the exposure device is installed at the tail end of the six-axis collaborative mechanical arm; the control unit comprises an industrial computer and a motion controller; the exposure device comprises a steel ball and a film box, the steel ball is fixedly connected with the film box through a first connecting rod, the film box is fixedly connected with the tail end of the six-axis collaborative mechanical arm through a second connecting rod, one end of the second connecting rod is fixed on the geometric center of the lower surface of the film box, the axis of the first connecting rod passes through the steel ball, and one end of the first connecting rod is fixed on the geometric center of the upper surface of the film box. Based on the real-time pose compensation and millisecond-level control closed loop of the six-axis collaborative mechanical arm, the isocenter is locked in the whole movement process of the treatment mechanical arm to realize high-precision dynamic calibration of the isocenter position of the radiotherapy mechanical arm, and the accuracy and safety of radiotherapy are improved.

Description

Technical Field

[0001] This application relates to the field of efficient dynamic verification and calibration technology for isocenter accuracy of radiotherapy systems, and in particular to a dynamic calibration device and method for isocenter point of a radiotherapy robotic arm. Background Technology

[0002] In radiotherapy, the isocenter accuracy of robotic arm systems typically requires sub-millimeter levels, directly impacting the irradiation effect on the tumor target area. Traditional calibration methods using static supports and standard phantoms have significant drawbacks: 1. Inability to simulate dynamic motion: During treatment, the robotic arm moves continuously, and static calibration cannot reflect isocenter drift under dynamic pose; 2. Cumbersome and inefficient operation: Repeated adjustments to the phantom position are required, relying on experience and being time-consuming; 3. Introduction of human error: Manual interpretation of film images is prone to visual errors. There is an urgent need for a calibration scheme that can follow the movement of the treatment arm in real time, automatically record, and quantify dynamic isocenter accuracy.

[0003] Therefore, we propose a dynamic calibration device and method for the center point of a radiotherapy robotic arm.

[0004] Application content

[0005] To address the shortcomings of existing manufacturing technologies, the applicant provides a dynamic calibration device and method for isocenter points of a radiotherapy robotic arm. Based on real-time pose compensation and millisecond-level control closed loop of a six-axis collaborative robotic arm, the isocenter point is locked throughout the entire movement of the robotic arm, achieving high-precision dynamic calibration of the isocenter position of the radiotherapy robotic arm and improving the accuracy and safety of radiotherapy.

[0006] The technical solution adopted in this application is as follows:

[0007] A dynamic isocenter calibration device for a radiotherapy robotic arm, used for dynamic isocenter calibration of the robotic arm, comprising:

[0008] Six-axis collaborative robotic arm;

[0009] Exposure device, mounted at the end of a six-axis collaborative robotic arm;

[0010] Control units, including industrial computers and motion controllers;

[0011] The exposure device includes a steel ball and a film cassette. The steel ball is fixedly connected to the film cassette via a first connecting rod. The film cassette is fixedly connected to the end of a six-axis collaborative robotic arm via a second connecting rod. One end of the second connecting rod is fixed to the geometric center of the lower surface of the film cassette. The axis of the first connecting rod passes through the steel ball, and one end of the first connecting rod is fixed to the geometric center of the upper surface of the film cassette.

[0012] Its further features are:

[0013] The film cassette has a hollow interlayer, into which film can be inserted.

[0014] The six-axis collaborative robotic arm communicates with the motion controller via a CAN bus, with a control cycle of ≤1ms and an end-effector repeatability of ≤0.05mm.

[0015] This application also discloses a method for dynamic calibration of the isocenter point of a radiotherapy robotic arm, including the following steps:

[0016] The first step is to establish the coordinate system transformation relationship between the treatment robot and the six-axis collaborative robot based on the pre-calibrated transformation relationship between the treatment robot coordinate system and the six-axis collaborative robot coordinate system.

[0017] The second step is to control the movement of the six-axis collaborative robotic arm 1 by the motion controller so that the center of the steel ball at the end of the six-axis collaborative robotic arm is aligned with the isocenter point of the treatment robotic arm.

[0018] The third step involves the robotic arm moving to each test point along a pre-set trajectory and emitting rays at each test point.

[0019] The fourth step is that the motion controller calculates the motion trajectory of the six-axis collaborative robotic arm end based on the real-time pose of the treatment robotic arm at the radiation beam test point, and drives the six-axis collaborative robotic arm to follow the changes in the radiation field of the treatment robotic arm, so that the film is always perpendicular to the beam and the steel ball is always located at a fixed point in space.

[0020] The fifth step is to obtain the exposure data of the film after radiation irradiation, calculate the deviation between the center of the radiation field and the center of the steel ball, that is, the deviation between the center of the radiation field and the isocenter point, and feed the results back to the treatment robotic arm control system to correct the parameters.

[0021] Step 6: Repeat steps 1 to 5 3-4 times.

[0022] Prior to calibration, the pre-calibration of the therapeutic robotic arm coordinate system and the six-axis collaborative robotic arm coordinate system includes the following steps:

[0023] Laser tracker target balls were installed at the end of the treatment robotic arm and the end of the six-axis collaborative robotic arm, respectively.

[0024] The spatial coordinate data of the target ball at the end of the treatment robotic arm and the six-axis collaborative robotic arm in multiple different poses were simultaneously acquired using a laser tracker.

[0025] Based on the collected spatial coordinate data, the transformation matrix between the coordinate system of the treatment robotic arm and the coordinate system of the six-axis collaborative robotic arm is calculated using a coordinate transformation algorithm.

[0026] The target ball is a 1.5-inch reflective target ball, the laser tracker is an APIT3 laser tracker, and the motion controller is a TRIO motion controller.

[0027] The industrial computer calculates the transformation matrix T between the coordinate system of the treatment robot and the coordinate system of the six-axis collaborative robot using a coordinate transformation algorithm. The industrial computer then calculates the rotation matrix R and translation vector t of the transformation matrix T using the SVD algorithm. The residual RMS of the result is <0.03mm.

[0028] The industrial computer converts the center coordinates P_tx of the treatment robotic arm into the coordinates P_co of the collaborative arm through the transformation matrix T, and sends it to the motion controller. The motion controller plans the joint space trajectory of the six-axis collaborative robotic arm and positions the steel ball to P_co within 5 seconds. The laser tracker verifies that the positioning error is ≤0.04mm.

[0029] The robotic arm performs a spiral test trajectory at a speed of 10° / s. The motion controller collects, processes, and sends out the processing results in real time at a frequency of 1kHz. The joint encoder data of the robotic arm is obtained through the EtherCAT bus. The motion controller calculates the position increment ΔX and attitude increment Δθ that need to be compensated in the coordinate system of the six-axis collaborative robotic arm. The motion controller drives the six-axis collaborative robotic arm to make the position fluctuation of the steel ball <0.05mm and the angle between the film normal vector and the beam axis <0.5°.

[0030] Film images were acquired using an Epson Expression 12000XL scanner with a resolution of 1200 dpi. Based on the OpenCV open-source image library, a program written in Python was used for image processing. The image processing steps are as follows: identify the projected ellipse of the steel ball and fit its center; calculate the centroid of the projected field; calculate the isocenter deviation; and output the test point deviation value.

[0031] The beneficial effects of this application are as follows:

[0032] This application features a compact and rational structure, and is easy to operate. Based on real-time pose compensation and millisecond-level control closed loop (≤1ms) of a six-axis collaborative robotic arm, it locks the isocenter point throughout the entire movement of the treatment robotic arm, ensuring that the spatial positioning fluctuation of the steel ball is ≤0.05mm. This represents a more than 5-fold improvement in accuracy compared to static calibration methods, and for the first time solves the problem of dynamic drift quantification. From the pre-calibration of the transformation relationship between the treatment robotic arm coordinate system and the six-axis collaborative robotic arm coordinate system, to the synchronous tracking of the beam trajectory and AI image analysis, all manual intervention is eliminated, improving calibration efficiency by 80% and achieving an error repeatability of ±0.02mm. This establishes a new standard for dynamic isocenter verification in radiotherapy, and its high precision and robustness are of groundbreaking significance for improving the safety of clinical treatment.

[0033] In addition, this application also has the following advantages:

[0034] (1) The industrial computer in the control unit calculates the coordinates of the radiotherapy center point based on the preset coordinate system transformation relationship, and then sends it to the motion controller to plan the motion path. This realizes the automation of the calibration process calculation and path planning, replacing manual calculation and operation, greatly reducing human error and improving calibration efficiency. The motion controller can dynamically calculate the end motion trajectory of the six-axis collaborative robotic arm based on the real-time pose of the treatment robotic arm at the test point, ensuring that the steel ball is always located at a fixed point in space and the film is perpendicular to the beam. This dynamic adaptive control capability can cope with the posture changes of the treatment robotic arm at different test points, avoid calibration failure caused by fixed trajectory control, and improve the adaptability of the device to complex calibration scenarios.

[0035] (2) The six-axis collaborative robotic arm possesses multi-degree-of-freedom motion capabilities, allowing for flexible adjustment of the end-effector's posture to meet the precise positioning requirements at different test points. This provides a hardware foundation for the precise alignment of the steel ball with the isocenter point and the stable maintenance of the film perpendicular to the beam, effectively avoiding calibration deviations caused by robotic arm positioning errors and ensuring the accuracy of subsequent field alignment error calculations. Simultaneously, the use of CAN bus communication with a control cycle ≤1ms enables high-speed real-time control of the six-axis collaborative robotic arm 1 by the motion controller. This ensures that during the dynamic movement of the treatment robotic arm, the six-axis collaborative robotic arm can quickly respond to changes in the field and adjust its end-effector trajectory in a timely manner, avoiding problems such as the film not being perpendicular to the beam and the steel ball deviating from the spatial stationary point due to control delays, thus improving the real-time performance and reliability of dynamic calibration.

[0036] (3) The coordinate transformation algorithm possesses mature mathematical logic and can accurately calculate the transformation matrix between the coordinate systems of the treatment robotic arm and the six-axis collaborative robotic arm based on multiple sets of collected spatial coordinate data. This avoids the tediousness and errors of manual calculation and improves the calculation efficiency and accuracy of the transformation matrix. The acquisition of the transformation matrix provides a crucial mathematical basis for subsequent operations such as the coordinated motion control of the treatment robotic arm and the six-axis collaborative robotic arm, and the precise positioning of the steel ball. This ensures that the entire calibration process is carried out in an orderly manner under a unified coordinate system, further guaranteeing calibration accuracy. Attached Figure Description

[0037] Figure 1 This is a schematic diagram illustrating the dynamic calibration of the center point of the therapeutic robotic arm in this application.

[0038] Figure 2 This is a schematic diagram of the six-axis collaborative robotic arm and exposure device of this application.

[0039] Among them: 1. Six-axis collaborative robotic arm; 2. Exposure device;

[0040] 201. Steel ball; 202. Film box; 203. First connecting rod; 204. Second connecting rod; 205. Film. Detailed Implementation

[0041] The specific embodiments of this application are described below with reference to the accompanying drawings.

[0042] like Figures 1-2 As shown, a dynamic isocenter calibration device for a radiotherapy robotic arm includes a six-axis collaborative robotic arm 1, an exposure device 2, and a control unit, used for dynamic isocenter calibration of the treatment robotic arm 3.

[0043] Exposure device 2 is installed at the end of a six-axis collaborative robotic arm 1. Exposure device 2 includes a steel ball 201 and a film cassette 202. The steel ball 201 is fixedly connected to the film cassette 202 via a first connecting rod 203. The first connecting rod 203 passes through the steel ball 201, or its axis passes through the steel ball 201. One end of the first connecting rod 203 is fixed to the geometric center of the upper surface of the film cassette 202. The film cassette 202 has a hollow interlayer into which film 205 can be inserted for recording X-ray exposure images.

[0044] The hollow compartment of the film cassette 202 allows for easy insertion of the film 205, facilitating film 205 replacement and data acquisition after exposure, reducing operational complexity, and improving the convenience of the calibration process. The film 205 clearly records X-ray exposure images, providing intuitive and accurate raw data support for subsequent acquisition of exposure data and calculation of field center and isocenter deviations. Compared to other image recording methods, the film 205 offers higher recording stability, is less susceptible to external interference, and ensures data reliability.

[0045] The film cassette 202 is fixedly connected to the end of the six-axis collaborative robotic arm 1 via a second connecting rod 204, one end of which is fixed at the geometric center of the lower surface of the film cassette 202.

[0046] This design ensures that the center of the steel ball 201 and the geometric center of the film cassette 202 are precisely aligned in space. This design allows the steel ball 201 to serve as a clear spatial reference point. When calculating the field alignment error using the positional deviation between the exposure mark on the film 205 and the center of the steel ball 201, there is no need for additional calibration of the relative positions of the steel ball 201 and the film cassette 202. This reduces calibration steps, improves efficiency, and avoids errors introduced by the relative positional offset of the two, ensuring the accuracy of error calculation.

[0047] The control unit includes an industrial computer and a motion controller. Based on the pre-calibrated transformation relationship between the coordinate system of the treatment robotic arm 3 and the coordinate system of the six-axis collaborative robotic arm 1, the industrial computer calculates the coordinates of the radiotherapy isocenter point in the coordinate system of the six-axis collaborative robotic arm 1, and then sends it to the motion controller to plan the motion path of the six-axis collaborative robotic arm 1, so that the steel ball 201 carried by the six-axis collaborative robotic arm 1 is accurately positioned to the isocenter point. The motion controller calculates the end effector trajectory of the six-axis collaborative robotic arm 1 in real time according to the pose of the treatment robotic arm 3 at the radiation beam test point, and drives the six-axis collaborative robotic arm 1 to follow the changes in the radiation field of the treatment robotic arm 3, so that the film 205 is perpendicular to the beam of the treatment robotic arm 3, and the steel ball 201 is always located at a fixed point in space. The treatment robotic arm 3 emits radiation streams at each test point, and the radiation field alignment error is calculated by the positional deviation between the exposure mark of the film 205 and the center of the steel ball 201.

[0048] The six-axis collaborative robotic arm 1 communicates with the motion controller via a CAN bus, with a control cycle of ≤1ms and an end-effector repeatability of ≤0.05mm.

[0049] The industrial computer in the control unit calculates the coordinates of the radiotherapy isocenter based on a preset coordinate system transformation relationship, and then sends the results to the motion controller to plan the motion path. This automates the calibration process, replacing manual calculation and operation, significantly reducing human error and improving calibration efficiency. The motion controller dynamically calculates the end effector trajectory of the six-axis collaborative robotic arm 1 based on the real-time pose of the robotic arm 3 at the test point, ensuring that the steel ball 201 remains stationary in space and the film 205 is perpendicular to the beam. This dynamic adaptive control capability can handle posture changes at different test points of the robotic arm 3, avoiding calibration failures caused by fixed trajectory control and improving the device's adaptability to complex calibration scenarios.

[0050] The six-axis collaborative robotic arm 1 possesses multi-degree-of-freedom motion capabilities, allowing for flexible adjustment of the end effector's posture to meet the precise positioning requirements at different test points. It provides the hardware foundation for the precise alignment of the steel ball 201 with the isocenter point and the stable perpendicularity of the film 205 to the beam, effectively avoiding calibration deviations caused by robotic arm positioning errors and ensuring the accuracy of subsequent field alignment error calculations. Simultaneously, employing CAN bus communication with a control cycle ≤1ms, it achieves high-speed real-time control of the six-axis collaborative robotic arm 1 by the motion controller. This ensures that during the dynamic movement of the treatment robotic arm 3, the six-axis collaborative robotic arm 1 can quickly respond to changes in the field and adjust its end effector trajectory in a timely manner, avoiding problems such as the film 205 not being perpendicular to the beam and the steel ball 201 deviating from its spatial stationary point due to control delays, thus improving the real-time performance and reliability of dynamic calibration.

[0051] Based on the real-time pose compensation and millisecond-level control closed loop (≤1ms) of the six-axis collaborative robotic arm 1, the center point is locked throughout the entire movement of the treatment robotic arm 3, so that the spatial positioning fluctuation of the steel ball 201 is ≤0.05mm, which is more than 5 times more accurate than the static calibration method, and solves the problem of dynamic drift quantification for the first time.

[0052] From the pre-calibration of the transformation relationship between the 3-coordinate system of the treatment robotic arm and the 1-coordinate system of the six-axis collaborative robotic arm, to the synchronous tracking of the beam trajectory and AI image analysis, the entire process eliminates manual intervention, improves calibration efficiency by 80%, and achieves an error repeatability of ±0.02mm. This establishes a new standard for dynamic isocenter validation in radiotherapy, and its high precision and robustness are of groundbreaking significance for improving the safety of clinical treatment.

[0053] A method for dynamic calibration of the isocenter point of a radiotherapy robotic arm includes the following steps:

[0054] The first step is to establish the coordinate system transformation relationship between the treatment robot arm 3 and the six-axis collaborative robot arm 1 based on the pre-calibrated transformation relationship between the coordinate system of the treatment robot arm 3 and the six-axis collaborative robot arm 1.

[0055] The second step is to control the movement of the six-axis collaborative robotic arm 1 by the motion controller so that the center of the steel ball 201 at the end of the six-axis collaborative robotic arm 1 is aligned with the isocenter point of the treatment robotic arm 3.

[0056] The third step is that the treatment robotic arm 3 moves to each test point according to the preset trajectory and emits rays at each test point;

[0057] The fourth step is that the motion controller calculates the end motion trajectory of the six-axis collaborative robotic arm 1 in real time based on the real-time pose of the treatment robotic arm 3 at the radiation beam test point, and drives the six-axis collaborative robotic arm 1 to follow the changes in the radiation field of the treatment robotic arm 3, so that the film 205 is always perpendicular to the beam and the steel ball 201 is always located at a fixed point in space.

[0058] The fifth step is to obtain the exposure data of the film 205 after radiation irradiation, calculate the deviation between the center of the radiation field and the center of the steel ball 201, that is, the deviation between the center of the radiation field and the isocenter point, and feed the results back to the radiotherapy control system to correct the parameters.

[0059] Step 6: Repeat steps 1 to 5 3-4 times.

[0060] The pre-calibration of the 3-axis coordinate system of the treatment robot and the 1-axis coordinate system of the six-axis collaborative robot is performed before calibration, and includes the following steps:

[0061] Laser tracker target balls were installed at the ends of the treatment robotic arm 3 and the six-axis collaborative robotic arm 1, respectively.

[0062] The spatial coordinate data of the target ball at the end of the treatment robotic arm 3 and the six-axis collaborative robotic arm 1 in multiple different poses were simultaneously acquired using a laser tracker.

[0063] Based on the collected spatial coordinate data, the transformation matrix between the 3-coordinate system of the treatment robotic arm and the 1-coordinate system of the six-axis collaborative robotic arm is calculated using a coordinate transformation algorithm.

[0064] The target ball of the laser tracker serves as a high-precision position measurement marker. Its small size and high positioning accuracy allow it to accurately reflect the spatial position of the robotic arm's end effector. Installing target balls at the ends of the treatment robotic arm 3 and the six-axis collaborative robotic arm 1 provides the laser tracker with clear and stable measurement targets, avoiding position data acquisition errors caused by unclear measurement targets and ensuring the accuracy of subsequent coordinate data acquisition.

[0065] Synchronous data acquisition ensures that the positional relationship between the ends of the treatment robotic arm 3 and the six-axis collaborative robotic arm 1 is recorded at the same time, avoiding coordinate data misalignment caused by asynchronous acquisition time and guaranteeing the authenticity of the relative positional relationship between the treatment robotic arm 3 and the six-axis collaborative robotic arm 1. Acquiring data from multiple different poses provides richer sample information, reduces the impact of random errors in data from a single pose on the calculation of the transformation matrix, and improves the accuracy of the transformation matrix calculation through fitting and analysis of multiple sets of data, ensuring the accuracy of subsequent coordinate system transformations.

[0066] The coordinate transformation algorithm possesses mature mathematical logic, capable of accurately calculating the transformation matrix between the coordinate systems of the treatment robotic arm 3 and the six-axis collaborative robotic arm 1 based on multiple sets of collected spatial coordinate data. This avoids the tediousness and errors of manual calculation, improving the efficiency and accuracy of the transformation matrix calculation. Obtaining the transformation matrix provides crucial mathematical basis for subsequent operations such as the coordinated motion control of the treatment robotic arm 3 and the six-axis collaborative robotic arm 1, and the precise positioning of the steel ball 201. This ensures that the entire calibration process is carried out in an orderly manner within a unified coordinate system, further guaranteeing calibration accuracy.

[0067] In one embodiment,

[0068] Laser tracker target balls were installed at the end of the treatment robotic arm 3 and the end of the six-axis collaborative robotic arm 1, respectively. The target balls were 1.5-inch reflective target balls, and the laser trackers were API T3 laser trackers.

[0069] The APIT3 laser tracker was used to simultaneously acquire 10 sets of target ball center coordinates under non-coplanar poses of the treatment robotic arm 3 and the six-axis collaborative robotic arm 1.

[0070] Based on the collected spatial coordinate data, the industrial computer calculates the transformation matrix T between the 3 coordinate system of the treatment robot and the 1 coordinate system of the six-axis collaborative robot using a coordinate transformation algorithm. The industrial computer then calculates the rotation matrix R and translation vector t of the transformation matrix T using the SVD algorithm. The residual RMS of the result is <0.03mm.

[0071] The industrial computer converts the isocenter coordinates P_tx of the treatment robotic arm 3 into the coordinates P_co of the collaborative arm using a transformation matrix T, and sends the results to the motion controller. The motion controller is a TRIO motion controller. The motion controller plans the joint spatial trajectory of the six-axis collaborative robotic arm 1 and positions the steel ball 201 to P_co within 5 seconds. The laser tracker verifies that the positioning error is ≤0.04mm. The motion controller communicates with the treatment robotic arm via an EtherCAT bus.

[0072] The therapeutic robotic arm 3 executes a spiral test trajectory at a speed of 10° / s. The motion controller acquires, processes, and sends out the processing results in real time at a frequency of 1kHz. The joint encoder data of the therapeutic robotic arm 3 is acquired via EtherCAT bus. The motion controller calculates the position increment ΔX and attitude increment Δθ that need to be compensated in the end-effector coordinate system of the six-axis collaborative robotic arm 1. The motion controller drives the six-axis collaborative robotic arm 1 to make the position fluctuation of the steel ball 201 <0.05mm and the angle between the normal vector of the film 205 and the beam axis <0.5°. Each test point is irradiated with 2MUX rays with an energy of 6MV, and a total of 20 spatial pose points are tested.

[0073] Take out film 205 and acquire the image using an Epson Expression 12000XL scanner with a resolution of 1200 dpi. Based on the OpenCV open-source image library, a program written in Python is used for image processing. The image processing steps are as follows: identify the projected ellipse of steel ball 201 and fit the center; calculate the centroid of the projected field; calculate the isocenter deviation (mm); output the deviation values ​​of 20 test points.

[0074] The deviation vector was imported into the control system of the therapeutic robotic arm 3, triggering the kinematic parameter optimization module of the therapeutic robotic arm 3; the link parameters in the Denavit-Hartenberg model were updated, and after 3 iterations, the dynamic isocenter accuracy was improved to within 0.08mm.

[0075] Specifically, the control system of the treatment robotic arm 3 is CyberKnife CPS.

[0076] The above description is an explanation of this application and not a limitation thereof. The scope of this application is defined by the claims. Within the scope of protection of this application, any form of modification may be made.

Claims

1. A dynamic calibration device for the isocenter of a radiotherapy robotic arm, used for dynamic isocenter calibration of a radiotherapy robotic arm (3), characterized in that, include: Six-axis collaborative robotic arm (1); Exposure device (2) is installed at the end of a six-axis collaborative robotic arm (1); Control units, including industrial computers and motion controllers; The exposure device (2) includes a steel ball (201) and a film cassette (202). The steel ball (201) is fixedly connected to the film cassette (202) via a first connecting rod (203). The film cassette (202) is fixedly connected to the end of a six-axis collaborative robotic arm (1) via a second connecting rod (204). One end of the second connecting rod (204) is fixed at the geometric center of the lower surface of the film cassette (202). The axis of the first connecting rod (203) passes through the steel ball (201), and one end of the first connecting rod (203) is fixed at the geometric center of the upper surface of the film cassette (202). The film cassette (202) is provided with a hollow interlayer, and film (205) can be inserted into the hollow interlayer. The six-axis collaborative robotic arm (1) communicates with the motion controller via a CAN bus, with a control cycle of ≤1ms and an end-effector repeatability of ≤0.05mm.

2. A method for dynamic calibration of the isocenter point of a radiotherapy robotic arm, using the dynamic calibration device for the isocenter point of a radiotherapy robotic arm as described in claim 1, characterized in that, Includes the following steps: The first step is to establish the coordinate system transformation relationship between the treatment robot (3) and the six-axis collaborative robot (1) based on the pre-calibrated transformation relationship between the coordinate system of the treatment robot (3) and the coordinate system of the six-axis collaborative robot (1); The second step is to control the movement of the six-axis collaborative robotic arm 1 by the motion controller so that the center of the steel ball (201) at the end of the six-axis collaborative robotic arm (1) is aligned with the isocenter point of the treatment robotic arm (3); The third step is that the treatment robotic arm (3) moves to each test point according to the preset trajectory and emits rays at each test point; In the fourth step, the motion controller calculates the end motion trajectory of the six-axis collaborative robotic arm (1) in real time based on the real-time pose of the treatment robotic arm (3) at the radiation beam test point, and drives the six-axis collaborative robotic arm (1) to follow the changes in the radiation field of the treatment robotic arm (3), so that the film (205) is always perpendicular to the beam and the steel ball (201) is always located at a fixed point in space. The fifth step is to obtain the exposure data of the film (205) after irradiation, calculate the deviation between the center of the radiation field and the center of the steel ball (201), that is, the deviation between the center of the radiation field and the isocenter point, and feed the results back to the control system of the treatment robotic arm (3) to correct the parameters. Step 6: Repeat steps 1 to 5 3-4 times.

3. The method for dynamic calibration of the isocenter point of a radiotherapy robotic arm as described in claim 2, characterized in that, Before calibration, the coordinate system of the therapeutic robotic arm (3) and the coordinate system of the six-axis collaborative robotic arm (1) are pre-calibrated, including the following steps: Laser tracker target balls are installed at the ends of the treatment robotic arm (3) and the six-axis collaborative robotic arm (1), respectively; The spatial coordinate data of the target ball at the end of the treatment robotic arm (3) and the six-axis collaborative robotic arm (1) in multiple different poses were simultaneously acquired using a laser tracker. Based on the collected spatial coordinate data, the transformation matrix between the coordinate system of the treatment robotic arm (3) and the coordinate system of the six-axis collaborative robotic arm (1) is calculated by the coordinate transformation algorithm.

4. The method for dynamic calibration of the isocenter point of a radiotherapy robotic arm as described in claim 3, characterized in that: The target ball is a 1.5-inch reflective target ball, the laser tracker is an API T3 laser tracker, and the motion controller is a TRIO motion controller.

5. The method for dynamic calibration of the isocenter point of a radiotherapy robotic arm as described in claim 4, characterized in that: The industrial computer calculates the transformation matrix T between the coordinate system of the treatment robotic arm (3) and the coordinate system of the six-axis collaborative robotic arm (1) through the coordinate transformation algorithm. The industrial computer calculates the rotation matrix R and translation vector t of the transformation matrix T through the SVD algorithm. The residual RMS of the result is <0.03mm.

6. The method for dynamic calibration of the isocenter point of a radiotherapy robotic arm as described in claim 5, characterized in that: The industrial computer converts the center coordinates P_tx of the treatment robotic arm (3) into the coordinates P_co of the collaborative arm through the transformation matrix T, and sends it to the motion controller. The motion controller plans the joint space trajectory of the six-axis collaborative robotic arm (1) and positions the steel ball (201) to P_co within 5 seconds. The laser tracker verifies that the positioning error is ≤0.04mm.

7. The method for dynamic calibration of the isocenter point of a radiotherapy robotic arm as described in claim 6, characterized in that: The therapeutic robotic arm (3) executes a spiral test trajectory at a speed of 10° / s. The motion controller collects data, processes data and sends out processing results in real time at a frequency of 1kHz: the joint encoder data of the therapeutic robotic arm (3) is obtained through the EtherCAT bus; the motion controller calculates the position increment ΔX and attitude increment Δθ that need to be compensated in the coordinate system of the end of the six-axis collaborative robotic arm (1); the motion controller drives the six-axis collaborative robotic arm (1) to make the position fluctuation of the steel ball (201) <0.05mm and the angle between the normal vector of the film (205) and the beam axis <0.5°.

8. The method for dynamic calibration of the isocenter point of a radiotherapy robotic arm as described in claim 7, characterized in that: The film (205) image was acquired using an Epson Expression 12000XL scanner with a resolution of 1200 dpi. Based on the OpenCV open-source image library, a program was written in Python to perform image processing. The image processing steps are as follows: identify the projected ellipse of the steel ball (201) and fit its center; calculate the centroid of the projected field. Calculate the isocenter deviation; output the test point deviation value.

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