A method and system for automatic adjustment of a CT tube

Abstract

The application discloses a kind of CT ball tube automatic adjusting method and system, method includes: after ball tube exposure, the X-ray that emits hits on detector, and detector output ray gray projection matrix to controller;Master control system identifies projection area boundary channel according to ray gray projection matrix and calculates projection barycentric pixel coordinate, and it is converted into projection plane physical coordinate in combination with detector single channel physical size;CT standard geometric parameter is acquired, and the focus relative isohedral offset of two adjustment dimensions of X direction and Z direction of ball tube is solved;The controller compares the focus relative isohedral offset of X, Z two-way that real-time measurement and pre-set standard coordinate, calculates position error, drives ball tube X / Z direction servo module dynamic feed compensation focus drift, forms acquisition-solution-two-way compensation real-time closed-loop control;The application improves ball tube adjustment speed and positioning accuracy, increases efficiency.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an automatic adjustment method and system for a CT tube. Background Technology

[0002] The CT tube is the core imaging component of a computed tomography (CT) scanner. The coaxiality and positional accuracy of the X-ray center emitted by the tube and the receiving center of the detector directly determine the CT image quality, scanning stability, and equipment lifespan.

[0003] Currently, the mainstream operating methods for pre-shipment testing, on-site replacement of X-ray tubes in hospitals, and post-X-ray tube maintenance are all manual repeated exposure and adjustment: technicians rely on detector feedback signals to trigger multiple exposures of the X-ray tube, manually fine-tuning the tube's installation position based on experience, and gradually correcting the offset between the X-ray center and the detector center until the imaging standards are met. This method has many drawbacks: 1. Extremely low replacement efficiency: Replacing a single CT tube and manually aligning it is time-consuming. Dual-source CT has two independent tube-detector systems, and the two systems need to be debugged and cross-validated separately, making the process more complicated, significantly extending equipment downtime and affecting clinical diagnosis and treatment. 2. Severe wear and tear on the X-ray tube: During manual adjustment, the position of the X-ray tube depends on the exposure of the X-ray tube. Moreover, due to the poor precision of manual adjustment, dozens of invalid exposures are required before the X-ray tube can be adjusted to the required position. This continuously consumes the X-ray tube filament and target surface, shortens the overall service life of the X-ray tube, and increases the hospital's operation and maintenance costs. 3. Unstable alignment accuracy: The debugging effect depends on the operator's experience and is prone to human error. Long-term use can easily lead to problems such as image artifacts and uneven dose distribution. 4. Limitations of Focus Drift Handling Methods: During prolonged continuous exposure, the X-ray tube's focus will physically shift due to the high temperature of the target surface. Current industry solutions rely solely on backend image algorithms for compensation and correction, without physically correcting the X-ray tube itself; this approach merely passively compensates for imaging defects. Summary of the Invention

[0004] Technical objective: To address the shortcomings of existing technologies, this invention discloses an automatic adjustment method and system for CT X-ray tubes, which improves the adjustment speed and positioning accuracy of the X-ray tubes and increases efficiency.

[0005] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution.

[0006] A method for automatic adjustment of a CT tube includes the following steps: Step S1: After the X-ray tube (100) is exposed, the emitted X-ray (1002) hits the detector (112), and the detector (112) outputs the X-ray grayscale projection matrix to the controller. Step S2: The main control system identifies the boundary channel of the projection area based on the ray grayscale projection matrix and calculates the pixel coordinates of the projection centroid, and converts them into the physical coordinates of the projection plane by combining the physical size of the detector single channel. Step S3: Obtain the standard CT geometric parameters and solve for the focal offset relative to the center of gravity in the X and Z axes of the X-ray tube. Step S4: The controller compares the real-time calculated X and Z bidirectional focal offset relative to the center with the preset standard coordinates, calculates the position error, and drives the X / Z of the X-ray tube to dynamically feed to the servo module to compensate for the focal drift, forming a real-time closed-loop control of acquisition-solution-bidirectional compensation.

[0007] The present invention also discloses an automatic adjustment system for a CT tube, which is used to realize the automatic adjustment method for a CT tube described above. The system includes: a CT tube (100), a front-back adjustment structure, a left-right adjustment structure, a controller, a detector, and a rotor local platform (109); the left-right adjustment structure and the front-back adjustment structure are arranged sequentially on the rotor local platform (109); the CT tube (100) is fixedly installed on the front-back adjustment structure; the controller is used to drive the front-back adjustment structure and the left-right adjustment structure, so that the CT tube (100) can adjust its position in the front-back and left-right directions on the rotor local platform (109), thereby realizing the automatic adjustment of the position of the CT tube.

[0008] Beneficial effects: 1. This invention improves the adjustment speed and positioning accuracy of the X-ray tube, thus increasing efficiency; 2. This invention achieves position adjustment through a single X-ray tube exposure, which greatly reduces the number of exposures and improves the service life of the X-ray tube compared to manual adjustment in the prior art; 3. This invention overcomes the limitations of existing focus drift response methods by fundamentally correcting deviations from a physical position, eliminating the need for image algorithm compensation. After automatically adjusting the position of the CT tube, this invention aligns the tube focus with the detector center, avoiding image artifacts and improving image quality and stability. Attached Figure Description

[0009] Figure 1 This is a flowchart of an automatic adjustment method for a CT tube according to an embodiment of the present invention; Figure 2 This is a schematic diagram of an automatic adjustment system for a CT tube according to an embodiment of the present invention; Figure 3 for Figure 2 Schematic diagram of the structure of the lead screw motor; Figure 4 for Figure 2A schematic diagram of X-rays; Figure 5 This is a control block diagram of an embodiment of the present invention; Figure 6 This is a schematic diagram of the offset in an embodiment of the present invention; Among them, 100-X-ray tube, 101-front and rear adjustment fixing plate, 102-front and rear guide rails, 103-first slider, 104-first lead screw motor, 105-left and right adjustment fixing plate, 106-left and right guide rails, 107-second slider, 108-second lead screw motor, 109-rotor partial platform, 110-second motor mounting base, 111-first motor mounting base; 1041-encoder, 1042-locking device, 1043-motor, 1044-lead screw nut, 1045-lead screw; 1001-focal point, 1002-X-ray beam, 1003-center, 1004-Z-direction centerline, 1005-X-direction centerline, 112-detector. Detailed Implementation

[0010] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application. Example

[0011] As attached Figure 1 Appendix Figure 5 and attached Figure 6 As shown, an automatic adjustment method for a CT tube in this embodiment includes the following steps: Step S1: After exposure by the X-ray tube (100), the emitted X-ray (1002) hits the detector (112), and the detector (112) outputs the X-ray grayscale projection matrix to the controller. In this embodiment, the X-ray is emitted from the focal point of the X-ray tube and projected onto the CT three-dimensional multi-row array detector through the gantry slit collimator. The three-dimensional multi-row detector synchronously acquires the X-ray grayscale projection matrix through multiple rows and columns of detection channels. Step S2: The main control system identifies the boundary channel of the projection area based on the ray grayscale projection matrix and calculates the pixel coordinates of the projection centroid. It then converts these coordinates into the physical coordinates of the projection plane by combining the physical dimensions of the detector's single channel. In this embodiment, the main control system includes a data receiving module and an algorithm module for data processing and calculation.

[0012] The process of calculating the projection centroid pixel coordinates includes: extracting four sets of boundary channels of the projection area through the boundary pixel set, and then obtaining the projection centroid pixel coordinates; The grayscale values ​​of all rows and columns of the 3D detector are obtained, taken from the ray grayscale projection matrix. A fixed grayscale threshold is set to distinguish between high grayscale channels with ray illumination and low grayscale channels without ray obstruction. Four sets of boundary channels of the projection area are extracted: the horizontal left boundary channel set. Horizontal right boundary channel set , Axial upper boundary channel set Axial lower boundary channel set The formula for calculating the pixel coordinates of the projection centroid is: , in, represents the projection centroid pixel coordinates in the horizontal X-axis and axial Z-axis, respectively, indicating the projection center pixel coordinates in the horizontal X-axis and axial Z-axis, i.e., the centroid projection pixel coordinates of the collimated slit beam on the imaging reference plane of the three-dimensional multi-row detector; mean is the average grayscale value of the channel within the set. These are the sets of horizontal left boundary channels, horizontal right boundary channels, axial left boundary channels, and axial right boundary channels, respectively.

[0013] The calculation process of the physical coordinates of the projection plane includes: obtaining the physical parameters of the three-dimensional detector, including the origin of the central channel of the three-dimensional detector assembly. Single channel physical horizontal width Single row physical axial height The physical coordinates of the projection plane are calculated based on the pixel coordinates of the projection centroid and the physical parameters of the 3D detector. The calculation formula is as follows: , in, The pixel coordinates of the projection centroid. These are the physical coordinates of the projection plane.

[0014] Step S3: Obtain the standard CT geometric parameters and solve for the focal offset relative to the center of gravity in the X and Z axes of the X-ray tube. The standard CT geometric parameters include the source isocenter distance (SID) and the vertical distance from the focus to the detector (SDD). SID is the fixed distance from the X-ray tube focus to the gantry scanning rotation center (isocenter). SDD is the total vertical distance from the X-ray tube focus to the incident surface of the three-dimensional multi-row detector. These standard CT geometric parameters are stored in the system. The SID / SDD ratio is then used to calculate the focus offset relative to the isocenter in the X and Z directions of the X-ray tube. In this embodiment, the mechanical structure of the equipment limits the X-ray tube to only have translation adjustment modules in the horizontal X and gantry axial Z directions. The total distance SDD in the X-ray emission Y direction is a fixed mechanical dimension of the entire machine, with no adjustment stroke, so there is no need to calculate the Y-coordinate.

[0015] Based on the simultaneous derivation of the geometric relationship between two levels of similar triangles in cone-beam perspective, after eliminating the collimator intermediate parameter SOD, only the X and Z bidirectional focal point offsets relative to the isocenters used for mechanism compensation are solved. The calculation formula is as follows: , in, This represents the horizontal X-axis focal offset. This is the focal offset in the Z-axis direction; , This is the bidirectional offset of the X-ray tube focal spot relative to the gantry scanning isocenter standard position at the current exposure moment, which is the focal spot offset relative to the isocenter and is the only valid input parameter for closed-loop compensation. During the calculation process, it only participates in the calibration of SID and SDD reference parameters during the equipment power-on self-test and factory geometric calibration stages. The clinical real-time focal spot offset solution only uses the ratio of SID to SDD, which simplifies the calculation logic and makes it efficient.

[0016] Step S4: The controller compares the real-time measured X and Z bidirectional focal point relative center offset with the preset standard coordinates, calculates the position error, and drives the X / Z servo module of the X-ray tube to dynamically feed to compensate for focal point drift, forming a real-time closed-loop control of acquisition-resolution-bidirectional compensation. Among them, the X-ray tube X-axis control is realized through the left and right adjustment structure of the CT X-ray tube automatic adjustment system, and the X-ray tube Z-axis control is realized through the front and rear adjustment structure of the CT X-ray tube automatic adjustment system.

[0017] The controller receives the calculated focus offset parameter (i.e., the focus offset relative to the center) in real time, and calculates the difference between it and the preset standard scanning focus target coordinates to obtain the bidirectional position error. The calculation formula is as follows: , in, The coordinates of the preset standard scanning focus target are: X represents the horizontal offset error, and Z represents the axial offset error. The controller outputs servo drive pulses based on two sets of offset errors, synchronously driving the X and Z direction precision servo modules of the X-tube moving mechanism for feeding.

[0018] As attached Figure 2 -Appendix Figure 4 As shown, this embodiment also discloses an automatic adjustment system for a CT tube, including: a tube (100), a front-back adjustment structure, a left-right adjustment structure, a controller, a detector, and a rotor local platform (109); the left-right adjustment structure and the front-back adjustment structure are arranged sequentially on the rotor local platform (109); the tube (100) is fixedly installed on the front-back adjustment structure; the controller is used to drive the front-back adjustment structure and the left-right adjustment structure, so that the tube (100) can adjust its position in the front-back and left-right directions on the rotor local platform (109), thereby realizing automatic position adjustment of the CT tube.

[0019] After exposure, the X-ray emitted by the X-ray tube (100) (1002) hits the detector (112). The detector (112) outputs a grayscale projection matrix of the X-ray to the controller. The controller obtains the position coordinates of a center (1003) on the Z-direction centerline (1004) and the X-direction centerline (1005) through the grayscale projection matrix of the X-ray. Based on the position coordinates of the center, the coordinate position deviation is obtained by comparing them with the material center of the detector. Thus, the position deviation value between the X-ray tube focal point (1001) and the material center of the detector is quickly obtained. The position deviation value is sent to the controller, which sends instructions to the motor drivers in the left-right adjustment structure and the front-back adjustment structure. The motor drivers drive the lead screw motor to move left-right and front-back, adjusting the X-ray tube to the specified position. The lead screw motor detects the motor movement position and positioning accuracy in real time through an encoder.

[0020] The left and right adjustment structure includes a left and right adjustment fixing plate (105), left and right guide rails (106), a second slider (107), a second lead screw motor (108), and a second motor mounting base (110); the left and right guide rails (106), the second slider (107), and the second motor mounting base (110) are fixedly installed on the rotor local platform (109), the left and right adjustment fixing plate (105) is fixed on the second slider (107), and the second lead screw motor (108) is fixed on the second motor mounting base (110); a lead screw nut is fixedly provided on the left and right adjustment fixing plate (105); The front-to-back adjustment structure has the same driving method as the left-to-right adjustment structure; the front-to-back adjustment structure includes a front-to-back adjustment fixing plate (101), a front-to-back guide rail (102), a first slider (103), a first lead screw motor (104), and a first motor mounting base (111); the front-to-back guide rail (102), the first slider (103), and the first motor mounting base (111) are fixedly installed on the left-to-right adjustment fixing plate (105), the front-to-back adjustment fixing plate (101) is fixed on the first slider (103), the first lead screw motor (104) is fixed on the first motor mounting base (111), and a lead screw nut is fixedly provided on the front-to-back adjustment fixing plate (101); the ball tube (100) is fixedly installed on the front-to-back adjustment fixing plate (101).

[0021] The first lead screw motor (104) and the second lead screw motor (108) have the same structure, including an encoder (1041), a locking device (1042), a motor (1043), a lead screw nut (1044), and a lead screw (1045). One end of the lead screw (1045) is equipped with the motor (1043), the locking device (1042), and the encoder (1041). The lead screw nut (1044) and the lead screw (1045) are threaded together. The controller controls the forward and backward movement of the X-ray tube (100). During motion control, the first lead screw motor (104) is driven. After the controller issues a motion command, the locking device (1042) is released, the motor (1043) rotates, and the lead screw (1045) rotates together, driving the lead screw nut (1044) to make linear motion. At the same time, it also drives the front and rear adjusting fixing plates (101) to make linear motion on the front and rear guide rails (102). The encoder (1042) detects the distance and positioning accuracy of the motor movement in real time. When the motion ends, the locking device (1042) locks. Similarly, when the controller controls the left and right movement of the X-ray tube (100), it drives the second lead screw motor (108). The control process is the same as the front and rear motion control.

[0022] This invention mounts the X-ray tube on an adjustable fixed plate, which can be adjusted forward, backward, left, and right by a motor. After the X-ray tube is exposed, the detector receives the X-ray and obtains the deviation position between the focal point of the X-ray tube and its own center. The deviation position is sent to the controller, which sends the offset data to the motor driver. The motor driver sends a command to the encoder to make the motor drive the X-ray tube to move to the precise specified position. Finally, the motor releases the brake and the X-ray tube is positioned.

[0023] In the embodiments of this application, the terms "first" and "second" (if they exist) are used only as name identifiers and do not represent the order of first and second.

[0024] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for automatic adjustment of a CT tube, characterized in that: Includes the following steps: Step S1: After the X-ray tube is exposed, the emitted X-rays hit the detector, and the detector outputs the X-ray grayscale projection matrix to the controller. Step S2: The main control system identifies the boundary channel of the projection area based on the ray grayscale projection matrix and calculates the pixel coordinates of the projection centroid, and converts them into the physical coordinates of the projection plane by combining the physical size of the detector single channel. Step S3: Obtain the standard CT geometric parameters and solve for the focal offset relative to the center of gravity in the X and Z axes of the X-ray tube. Step S4: The controller compares the real-time calculated X and Z bidirectional focal offset relative to the center with the preset standard coordinates, calculates the position error, and drives the X / Z of the X-ray tube to dynamically feed to the servo module to compensate for the focal drift, forming a real-time closed-loop control of acquisition-solution-bidirectional compensation.

2. The automatic adjustment method for a CT tube according to claim 1, characterized in that: The process of calculating the projection centroid pixel coordinates includes: extracting four sets of boundary channels for the projection region from the boundary pixel set, and then obtaining the projection centroid pixel coordinates. The formula for calculating the projection centroid pixel coordinates is as follows: ， in, Here are the pixel coordinates of the projection centroid, and mean is the average of the channel grayscale values ​​within the set. These are the sets of horizontal left boundary channels, horizontal right boundary channels, axial left boundary channels, and axial right boundary channels, respectively.

3. The automatic adjustment method for a CT tube according to claim 1, characterized in that: The calculation process of the physical coordinates of the projection plane includes: obtaining the physical parameters of the three-dimensional detector, including the origin of the central channel of the three-dimensional detector assembly. Single channel physical horizontal width Single row physical axial height The physical coordinates of the projection plane are calculated based on the pixel coordinates of the projection centroid and the physical parameters of the 3D detector.

4. The automatic adjustment method for a CT tube according to claim 3, characterized in that: The formula for calculating the physical coordinates of the projection plane is: ， in, The pixel coordinates of the projection centroid. These are the physical coordinates of the projection plane.

5. The automatic adjustment method for a CT tube according to claim 1, characterized in that: The formula for calculating the offset of the focus relative to the center is: ， in, This represents the horizontal X-axis focal offset. Z-axis focal offset; SID is the distance from the focal point to the rotation isocenter; SDD is the vertical distance from the focal point to the detector. These are the physical coordinates of the projection plane.

6. The automatic adjustment method for a CT tube according to claim 1, characterized in that: The formula for calculating bidirectional position error is: ， in, The coordinates of the preset standard scanning focus target are: X represents the horizontal offset error, and Z represents the axial offset error. This represents the horizontal X-axis focal offset. This represents the focal offset in the Z-axis direction.

7. A CT tube automatic adjustment system for implementing the CT tube automatic adjustment method as described in any one of claims 1-6, characterized in that: include: X-ray tube (100), front and rear adjustment structure, left and right adjustment structure, controller, detector and rotor local platform (109); A left-right adjustment structure and a front-back adjustment structure are sequentially arranged on the rotor local platform (109); the X-ray tube (100) is fixedly installed on the front-back adjustment structure; the controller is used to drive the front-back adjustment structure and the left-right adjustment structure so that the X-ray tube (100) can be adjusted in the front-back and left-right directions on the rotor local platform (109), thereby realizing automatic position adjustment of the CT X-ray tube.

8. The CT tube automatic adjustment system according to claim 7, characterized in that: The left and right adjustment structure includes a left and right adjustment fixing plate (105), left and right guide rails (106), a second slider (107), a second lead screw motor (108), and a second motor mounting base (110); the left and right guide rails (106), the second slider (107), and the second motor mounting base (110) are fixedly installed on the rotor local platform (109), the left and right adjustment fixing plate (105) is fixed on the second slider (107), and the second lead screw motor (108) is fixed on the second motor mounting base (110); a lead screw nut is fixedly provided on the left and right adjustment fixing plate (105).

9. The CT tube automatic adjustment system according to claim 8, characterized in that: The front-to-back adjustment structure has the same driving method as the left-to-right adjustment structure; the front-to-back adjustment structure includes a front-to-back adjustment fixing plate (101), a front-to-back guide rail (102), a first slider (103), a first lead screw motor (104), and a first motor mounting base (111); the front-to-back guide rail (102), the first slider (103), and the first motor mounting base (111) are fixedly installed on the left-to-right adjustment fixing plate (105), the front-to-back adjustment fixing plate (101) is fixed on the first slider (103), the first lead screw motor (104) is fixed on the first motor mounting base (111), and a lead screw nut is fixedly provided on the front-to-back adjustment fixing plate (101); the ball tube (100) is fixedly installed on the front-to-back adjustment fixing plate (101).

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