X-ray Tube Focus Automatic Positioning Device

Abstract

The present invention provides an X-ray tube focus automatic positioning device, comprising: a controller, an XY-axis moving platform, a Z-axis moving platform, an X-ray tube installed on the XY-axis moving platform, and a detector and a collimator installed on the Z-axis moving platform. The XY-axis moving platform includes an X-axis motor and a Y-axis motor for adjusting the X-ray tube to find the focus position. The Z-axis moving platform includes a Z-axis motor for moving the detector up and down to facilitate the disassembly and assembly of the X-ray tube. The controller controls the X-axis motor, Y-axis motor, and Z-axis motor in the following manner to achieve automatic positioning of the X-ray tube focus. The XY-axis motors can be controlled by the controller to move the X-ray tube. At the same time, based on the data sampled by the detector, it is determined whether the line connecting the focus of the X-ray tube and the center point of the hole of the collimator is perpendicular to the flange plane of the X-ray tube, forming a closed-loop feedback control system.

Description

Technical Field

[0001] The present invention relates to the field of X-ray tubes, and particularly to an automatic focusing device for an X-ray tube. Background Art

[0002] When detecting an X-ray tube, it is necessary to detect the focal position of the X-ray tube. Early X-ray tube detections only focused on detecting whether the X-ray tube leaked oil, and could not test various other characteristics of the X-ray tube, such as consistency, stability, output linearity, and whether there was discharge.

[0003] During operation, a high-voltage power supply applies a high voltage of tens of thousands of volts to the X-ray tube, and the X-ray tube generates X-rays to excite the sample to be measured. Each element in the excited sample emits secondary X-rays (fluorescent X-rays), and a photodetector converts these lights of different wavelengths into pulse signals of different heights, and then converts them into spectral data through a digital signal processor, and the computer controller can obtain the current count rate (X-ray intensity). When the high-voltage power supply outputs a constant tube voltage and tube current and the detector parameters are constant, there is a causal relationship between the intensity of the X-rays and the positional relationship between the focus and the small hole of the collimator. When the X-ray focal position and the center point of the small hole of the collimator are perpendicular to the flange plane of the X-ray tube, the maximum X-ray intensity can be obtained.

[0004] However, during the current X-ray tube detection process, there is no device for automatically positioning the focus of the X-ray tube, which affects the detection accuracy and effect. Summary of the Invention

[0005] The present invention provides an automatic focusing device for an X-ray tube to solve at least one of the above technical problems.

[0006] To solve the above problems, as an aspect of the present invention, an automatic focusing device for an X-ray tube is provided, including: a controller, an XY-axis moving platform, a Z-axis moving platform, an X-ray tube installed on the XY-axis moving platform, and a detector and a collimator installed on the Z-axis moving platform. The XY-axis moving platform includes an X-axis motor and a Y-axis motor for adjusting the X-ray tube to find the focal position, and the Z-axis moving platform includes a Z-axis motor for moving the detector up and down to facilitate the disassembly and assembly of the X-ray tube;

[0007] The controller controls the X-axis motor, Y-axis motor, and Z motor through the following method to achieve automatic focusing of the X-ray tube, including:

[0008] Set d x as the distance between the previous position and the moved position of the X-axis motor, d yis the distance between the previous position and the moved position of the Y-axis motor, x0 is the current X-axis coordinate point, and y0 represents the current Y-axis coordinate point;

[0009] Move the X-axis motor and the Y-axis motor to the coordinate origin and perform a test operation. The test operation includes: lowering the Z-axis to the test position for a 60s test and saving the count rate per second, saving the coordinate information of this test position and the average count rate from the 31st to the 60th second after the test is completed, and initializing d x and d y are initial values not equal to zero respectively;

[0010] Step 1, determine whether d x is equal to 0. If not, move the X-axis motor to execute loop A; if so, it means that the movement in the X-axis direction has ended. Move the X-ray tube to the coordinate origin, perform the test operation, and then start moving the Y-axis motor to execute loop B;

[0011] Step 2, after loop B ends, based on the final coordinate point (x0, 0.0) obtained from loop A and the final coordinate point (0.0, y0) obtained from loop B, the intersection coordinate of these two points is (x0, y0), and finally determine this point as the focus of the X-ray tube;

[0012] Among them, the loop A includes:

[0013] Step A1, determine whether after moving d x distance in the positive X-axis direction from the current coordinate point, it will exceed the positive X limit coordinate point used to prevent mechanical collision. If so, the X-axis motor moves in the positive direction by the first distance D1, where D1 = positive X limit coordinate point - x0. If not, the X-axis motor moves in the positive direction by d x distance; after moving in place, perform the test operation;

[0014] Step A2, determine whether after moving 2d x distance in the negative X-axis direction from the current coordinate point, it will exceed the negative X limit coordinate point used to prevent mechanical collision. If not, the X-axis motor moves in the negative direction by 2d x distance. If so, the X-axis motor moves in the negative direction by the second distance D2, where D2 = x0 + |negative X limit coordinate point|); after moving in place, perform the test operation;

[0015] Step A3, compare the average count rates of the three point positions obtained from the nearest three test operations in the X-axis direction, save the coordinate position information of the point with the largest average count rate and move to this point, and at the same time clear the other two groups of data;

[0016] Step A4, determine the current moving distance d xIs it equal to the first predetermined value? If not, reduce dx by half and return to step 1 to continue executing loop A; if so, set d x to 0;

[0017] Among them, the loop B includes:

[0018] Step B1, determine whether it will exceed the positive direction Y limit coordinate point for preventing mechanical collision after moving d y distance in the positive direction of the Y-axis from the current coordinate point. If so, the X-axis motor moves in the positive direction by a third distance D3, where D3 = positive direction Y limit coordinate point - y0. Otherwise, the Y-axis motor moves in the positive direction by d y distance; after moving in place, perform the test operation;

[0019] Step B2, determine whether it will exceed the negative direction Y limit coordinate point for preventing mechanical collision after moving 2d y distance in the negative direction of the Y-axis from the current coordinate point. If so, the Y-axis motor moves in the negative direction by 2d y distance. Otherwise, the X-axis motor moves in the negative direction by a fourth distance D4, where D4 = y0 + |negative direction Y limit coordinate point|; after moving in place, perform the test operation;

[0020] Step B3, compare the average counting rates of the three point positions obtained from the nearest three test operations in the Y-axis direction, save the coordinate point position information with the largest average counting rate and move to that point, and at the same time clear the other two groups of data;

[0021] Step B4, determine whether the current moving distance d y is equal to the second predetermined value. If not, reduce d y by half and return to step 1 to continue executing loop B; if so, set d y to 0.

[0022] Preferably, both the first predetermined value and the second predetermined value are 0.1 mm.

[0023] Preferably, after the controller moves the X-ray tube to the coordinate point (x0, y0), according to the Pythagorean theorem a 2 +b 2 =c 2 judge whether the distance between (x0, y0) and the coordinate origin (0.0, 0.0) is less than or equal to 2 millimeters. If so, determine that the focus position of the X-ray tube is qualified and end the focus positioning test. Otherwise, determine that the focus position of the X-ray tube is unqualified and end all current tests.

[0024] Due to the adoption of the above technical solution, the present invention can control the XY-axis motors by a controller to move the X-ray tube. At the same time, based on the data sampled by the detector, it is determined whether the line connecting the focus of the X-ray tube and the center point of the hole of the collimator is perpendicular to the flange plane of the X-ray tube, forming a closed-loop feedback control system. After alignment, the flange of the collimator and the X-ray tube is locked, and other characteristics of the X-ray tube are continuously tested. Detailed implementation mode

[0025] The following is a detailed description of the embodiments of the present invention. However, the present invention can be implemented in many different ways defined and covered by the claims.

[0026] Currently, due to various problems such as various assembly and packaging production processes, the actual focal spot of the X-ray tube and the center of the X-ray tube flange are not at the same point. The present invention can be used to find the position of the actual focal spot of the X-ray tube, so as to obtain the maximum X-ray intensity.

[0027] The X-ray tube focus automatic positioning device in the present invention includes a moving platform, and the moving platform includes an XY-axis moving platform and a Z-axis moving platform. Among them, the Z-axis closed-loop stepping motor drives the Z-axis T-shaped lead screw to rotate, thereby driving the Z-axis lead screw slider to move up and down; the Y-axis closed-loop stepping motor drives the Y-axis lead screw in the XY-axis moving platform to rotate, thereby driving the X-ray tube to move in the Y-axis direction; the X-axis closed-loop stepping motor drives the X-axis lead screw in the XY-axis moving platform to rotate, thereby driving the X-ray tube to move in the X-axis direction.

[0028] In the present invention, the X-ray tube is installed on the XY-axis moving platform, and the detector and the collimator are installed on the Z-axis moving slider to ensure the relative positions of the detector and the collimator remain unchanged, so as to ensure that the detector and the collimator do not affect the counting rate.

[0029] During operation, the controller controls the XY-axis moving platform to return to the initial position. At this time, the physical center of the X-ray tube flange and the center of the collimator coincide. When the controller controls the XY-axis moving platform to move in the positive X-axis direction, the closer the focal spot is to the center of the collimator, the larger the counting rate tested by the controller. When the controller controls the XY-axis moving platform to move in the negative X-axis direction, the farther the focal spot is from the center of the collimator, the smaller the counting rate tested by the controller. When the controller controls the XY-axis moving platform to move in the positive Y-axis direction, the farther the focal spot is from the center of the collimator, the smaller the counting rate tested by the controller. When the controller controls the XY-axis moving platform to move in the negative Y-axis direction, the closer the focal spot is to the center of the collimator, the larger the counting rate tested by the controller. When the XY-axis moves to the point where all the test data counting rates are at the maximum value, the center of the collimator is concentric with the actual focal spot, and the position of the actual focal spot of the X-ray tube is determined.

[0030] Among them, the controller can adopt the scheme of integrating a digital signal transfer board into a digital high-voltage power supply. The main control is an ARM Cortex-M3 (STM32F405) chip, which is responsible for ADC / DAC sampling and output. At the same time, it communicates with the embedded main board via 485.

[0031] Next, the positioning process of the focus automatic positioning algorithm in the present invention will be described in detail:

[0032] In the present invention, the test operation is implemented in the following manner: lower the Z-axis to the test position, conduct a 60-second test, and record the count rate value for each second. After the test is completed, raise the Z-axis to the safe position, take the average of the count rates from the 31st second to the 60th second, and save the average count rate value at this position and the XY coordinate information of the current position.

[0033] For the convenience of description, the following parameters are defined in the present invention:

[0034] Coordinate origin (0.0, 0.0): the position where the physical center of the X-ray tube flange coincides with the center of the collimator.

[0035] d x : the distance between the previous position and the moved position of the X-axis motor.

[0036] d y : the distance between the previous position and the moved position of the Y-axis motor.

[0037] x0: represents the current X-axis coordinate point.

[0038] y0: represents the current Y-axis coordinate point.

[0039] If the position of the X-ray tube focus is within the area centered at the coordinate origin (0.0, 0.0) with a radius of 2 mm, it is determined to be qualified. The initial moving strokes of the X-axis motor and the Y-axis motor are both set to 3.2 mm. The X-ray tube is moved to the established coordinate origin (0.0, 0.0) through the X-axis and Y-axis motors, and the test operation is executed.

[0040] The overall process of the present invention is as follows:

[0041] First, determine whether the moving distance d of the X-axis motor x = 0. If d x ≠ 0, then move the X-axis motor to execute loop A. If d x = 0, it means that the movement in the X-axis direction has ended. Move the X-ray tube to the coordinate origin, execute the test operation, and then start moving the Y-axis motor to execute loop B.

[0042] Secondly, after the end of Loop B, based on the final coordinate point (x0, 0.0) obtained from Loop A and the final coordinate point (0.0, y0) obtained from Loop B, the intersection coordinate of these two points is obtained as (x0, y0), and finally this point is determined as the focus of the X-ray tube.

[0043] Then, move the X-ray tube to the coordinate point (x0, y0), and then according to the Pythagorean theorem a 2 +b 2 =c 2 Judge whether the distance from (x0, y0) to the coordinate origin (0.0, 0.0) is less than or equal to 2 mm. If the distance is less than or equal to 2 mm, it is determined that the focus position of the X-ray tube is qualified, and the focus positioning test is ended. If the distance between (x0, y0) and the coordinate origin (0.0, 0.0) is greater than 2 mm, it is determined that the focus position of the X-ray tube is unqualified, and all current tests are ended.

[0044] Next, a detailed description is given to Loop A and Loop B involved in the above overall process respectively (this structural device restricts that the X and Y coordinates of the focus center do not exceed the X and Y coordinates of the coordinate origin center at plus or minus 4 mm).

[0045] (1) Loop A:

[0046] Judge whether the distance of moving the current coordinate point in the positive X-axis direction by d x will reach the position of the coordinate point (4.0, 0.0) to prevent mechanical collision due to exceeding the limit; if d x +x0>4.0, the X-axis motor moves in the positive direction by (4.0 - x0) mm, if d x +x0<=4.0, the X-axis motor moves in the positive direction by d x mm. After moving in place, perform the test operation.

[0047] Judge whether the distance of moving the current coordinate point in the negative X-axis direction by 2d x will reach the position of the coordinate point (-4.0, 0.0) to prevent mechanical collision due to exceeding the limit. If x0 - 2d x >= -4.0, the X-axis motor moves in the negative direction by 2d x distance; if x0 - 2d x < -4.0, the X-axis motor moves in the negative direction by (x0 + 4.0) mm. After moving in place, perform the test operation.

[0048] Compare the average count rates of these three point positions, save the information of the coordinate point position with the largest average count rate, and clear the data of the other two groups.

[0049] Judge whether the current moving distance d x = 0.1. If d xIf it is not equal to 0.1, the moving distance d x = d x / 2, reducing the moving distance by half. Also, since the moving distance d of the X-axis motor x ≠0, continue to loop A. If d x = 0.1, it means that the X-axis motor has found the position closest to the focus, and then modify the moving distance d x = 0 indicates that the movement in the X-axis direction has ended, and the loop ends.

[0050] (2) Loop B:

[0051] Judge whether the moving distance d in the positive Y-axis direction from the current coordinate point y will reach the position of the coordinate point (0.0, 4.0), to prevent mechanical collision due to exceeding the limit; if d y + y0 > 4.0, then the X-axis motor moves in the positive direction by (4.0 - y0) millimeters. If d y + y0 <= 4.0, then the Y-axis motor moves in the positive direction by d y millimeters. After moving in place, perform the test operation.

[0052] Judge whether the moving distance 2d in the negative Y-axis direction from the current coordinate point y will reach the position of the coordinate point (0.0, -4.0), to prevent mechanical collision due to exceeding the limit. If y0 - 2d y >= -4.0, then the Y-axis motor moves in the negative direction by 2d y distance; if y0 - 2d y < -4.0, then the X-axis motor moves in the negative direction by (y0 + 4.0) millimeters. After moving in place, perform the test operation.

[0053] Compare the average count rates of these three point positions, save the information of the coordinate point position with the largest average count rate, and clear the data of the other two groups.

[0054] Judge whether the current moving distance d y = 0.1. If d y ≠0.1, then the moving distance d y = d y / 2, reducing the moving distance by half, and continue to loop B. If d y = 0.1, it means that the X-axis motor has found the position closest to the focus, and the loop ends.

[0055] Next, through a specific embodiment, a more detailed explanation of the specific implementation process of the present invention will be given.

[0056] First, assume that the coordinate point (-2.2, 0.0) is the coordinate point closest to the focus, and set d xThe initial moving stroke is 3.2 mm. Then, the moving process and principle of the X-axis motor in cycle A are as follows:

[0057] The X- and Y-axis motors first move to the coordinate origin (0.0, 0.0) for a 60-s test and save the counting rate per second. After the test is completed, the coordinate information of this point and the average counting rate from the 31st s to the 60th s are saved;

[0058] Judging from x0 + d x = 3.2, it is obtained that the X-axis motor moves a distance of d in the positive X-axis direction from the position of the coordinate origin (0.0, 0.0) x and has not reached the point (4.0, 0.0).

[0059] ① Move a distance of d in the positive X-axis direction from the coordinate origin (0.0, 0.0) x to reach the point (3.2, 0.0). Conduct a 60-s test at this point and save the counting rate per second. After the test is completed, save the coordinate information of this point and the average counting rate from the 31st s to the 60th s;

[0060] Judging from x0 - 2d x = -3.2, it is obtained that the X-axis motor moves a distance of 2d in the negative X-axis direction from the position of the coordinate point (3.2, 0.0) x and has not reached the point (-4.0, 0.0).

[0061] ② Move a distance of 2d in the negative X-axis direction from the coordinate point (3.2, 0.0) x to reach the point (-3.2, 0.0). Conduct a 60-s test at this point and save the counting rate per second. After the test is completed, save the coordinate information of this point and the average counting rate from the 31st s to the 60th s;

[0062] Compare the magnitudes of the average counting rates of the three points (0.0, 0.0), (3.2, 0.0), and (-3.2, 0.0).

[0063] Assume that the average counting rate of the point (-3.2, 0.0) is the largest. Move to this coordinate point, use this coordinate point as the starting point for the next move, and clear the information of the two coordinate points (0.0, 0.0) and (3.2, 0.0).

[0064] Since the current d x is not yet 0.1 mm, the next moving stroke in the positive direction is d x = 3.2 / 2 = 1.6 mm.

[0065] Judging from x0 + d x = -1.6, it is obtained that the X-axis motor moves a distance of d in the positive X-axis direction from the position of the coordinate point (-3.2, 0.0)x The distance has not reached the point (4.0, 0.0).

[0066] ③ Move d in the positive X-axis direction from the coordinate point (-3.2, 0.0). x The distance reaches the point (-1.6, 0.0). Conduct a 60s test at this point and save the counting rate per second. After the test is completed, save the coordinate information of this point and the average counting rate from the 31st s to the 60th s;

[0067] Through x0 - 2d x It is judged by x0 - 2d = -4.8 that the X-axis motor moves 2d in the negative X-axis direction from the position of the coordinate point (-1.6, 0.0). x The distance will exceed the coordinate point (-4.0, 0.0). So move 2.4 mm in the negative X-axis direction, that is, x0 - (-4.0) = 2.4 mm.

[0068] ④ Move 2.4 mm in the negative X-axis direction from the coordinate point (-1.6, 0.0) to reach the point (-4, 0.0). Conduct a 60s test at this point and save the counting rate per second. After the test is completed, save the coordinate information of this point and the average counting rate from the 31st s to the 60th s;

[0069] Compare the average counting rates of the three points (-3.2, 0.0), (-1.6, 0.0), and (-4.0, 0.0).

[0070] Assume that the average counting rate of the point (-1.6, 0.0) is the largest. Move to this coordinate point, use this coordinate point as the starting point for the next movement, and clear the information of the two coordinate points (-3.2, 0.0) and (-4.0, 0.0).

[0071] Since the current d x is not yet 0.1 mm, the next forward movement distance is d x = 1.6 / 2 = 0.8 mm.

[0072] Through x0 + d x It is judged by x0 + d = -0.8 that the X-axis motor moves d in the positive X-axis direction from the position of the coordinate point (-1.6, 0.0). x The distance has not reached the point (4.0, 0.0).

[0073] ⑤ Move d in the positive X-axis direction from the coordinate point (-1.6, 0.0). x The distance reaches the point (-0.8, 0.0). Conduct a 60s test at this point and save the counting rate per second. After the test is completed, save the coordinate information of this point and the average counting rate from the 31st s to the 60th s;

[0074] Through x0 - 2dx = -2.4. It is determined that the X-axis motor moves 2d in the negative X-axis direction from the coordinate point (-0.8, 0.0). x The distance has not reached the point (-4.0, 0.0).

[0075] ⑥ Move 2d in the negative X-axis direction from the coordinate point (-0.8, 0.0). x The distance reaches the point (-2.4, 0.0). Conduct a 60s test at this point and save the counting rate per second. After the test is completed, save the coordinate information of this point and the average counting rate from the 31st s to the 60th s;

[0076] Compare the magnitudes of the average counting rates of the three points (-1.6, 0.0), (-0.8, 0.0), and (-2.4, 0.0).

[0077] Assume that the average counting rate of the point (-2.4, 0.0) is the largest. Move to this coordinate point, use this coordinate point as the starting point for the next movement, and clear the information of the two coordinate points (-0.8, 0.0) and (-1.6, 0.0).

[0078] Since the current d x is not yet 0.1 mm, the next movement distance in the positive direction is d x = 0.8 / 2 = 0.4 mm.

[0079] Through x0 + d x = -2.0. It is determined that the X-axis motor moves d in the positive X-axis direction from the coordinate point (-2.4, 0.0). x The distance has not reached the point (4.0, 0.0).

[0080] ⑦ Move d in the positive X-axis direction from the coordinate point (-2.4, 0.0). x The distance reaches the point (-2.0, 0.0). Conduct a 60s test at this point and save the counting rate per second. After the test is completed, save the coordinate information of this point and the average counting rate from the 31st s to the 60th s;

[0081] Through x0 - 2d x = -2.8. It is determined that the X-axis motor moves 2d in the negative X-axis direction from the coordinate point (-2.0, 0.0). x The distance has not reached the point (-4.0, 0.0).

[0082] ⑧ Move 2d in the negative X-axis direction from the coordinate point (-2.0, 0.0). xReach the point (-2.8, 0.0), conduct a 60s test at this point and save the count rate per second, and after the test is completed, save the coordinate information of this point and the average count rate from the 31st second to the 60th second;

[0083] Compare the average count rates of the three points (-2.4, 0.0), (-2.0, 0.0), and (-2.8, 0.0).

[0084] Assume that the average count rate of the point (-2.0, 0.0) is the largest, move to this coordinate point, use this coordinate point as the starting point for the next move, and clear the information of the two coordinate points (-2.4, 0.0) and (-2.8, 0.0).

[0085] Since the current d x is not yet 0.1mm, the next forward movement distance is d x = 0.4 / 2 = 0.2mm.

[0086] Through x0 + d x = -1.8, it is judged that the X-axis motor moves d x distance from the position of the coordinate point (-2.0, 0.0) in the positive X-axis direction and has not reached the point (4.0, 0.0).

[0087] ⑨ Move d x distance from the coordinate point (-2.0, 0.0) in the positive X-axis direction to reach the point (-1.8, 0.0), conduct a 60s test at this point and save the count rate per second, and after the test is completed, save the coordinate information of this point and the average count rate from the 31st second to the 60th second;

[0088] Through x0 - 2d x = -2.2, it is judged that the X-axis motor moves 2d x distance from the position of the coordinate point (-1.8, 0.0) in the negative X-axis direction and has not reached the point (-4.0, 0.0).

[0089] ⑩ Move 2d x distance from the coordinate point (-1.8, 0.0) in the negative X-axis direction to reach the point (-2.2, 0.0), conduct a 60s test at this point and save the count rate per second, and after the test is completed, save the coordinate information of this point and the average count rate from the 31st second to the 60th second;

[0090] Compare the average count rates of the three points (-2.0, 0.0), (-1.8, 0.0), and (-2.2, 0.0).

[0091] Assume that the average counting rate at the point (-2.2, 0.0) is the largest. Move to this coordinate point, and use this coordinate point as the starting point for the next move. Clear the information of the two coordinate points (-2.0, 0.0) and (-1.8, 0.0).

[0092] Since the current d x is not yet 0.1 mm, the next forward movement distance is d x = 0.2 / 2 = 0.1 mm.

[0093] Through x0 + d x = -2.1, it is judged that the X-axis motor moves d x distance from the position of the coordinate point (-2.2, 0.0) in the positive X-axis direction and has not reached the point (4.0, 0.0).

[0094] Move d x distance from the coordinate point (-2.2, 0.0) in the positive X-axis direction to reach the point (-2.1, 0.0). Conduct a 60s test at this point and save the counting rate per second. After the test is completed, save the coordinate information of this point and the average counting rate from the 31st s to the 60th s;

[0095] Through x0 - 2d x = -2.3, it is judged that the X-axis motor moves 2d x distance from the position of the coordinate point (-2.1, 0.0) in the negative X-axis direction and has not reached the point (-4.0, 0.0).

[0096] Move 2d x distance from the coordinate point (-2.1, 0.0) in the negative X-axis direction to reach the point (-2.3, 0.0). Conduct a 60s test at this point and save the counting rate per second. After the test is completed, save the coordinate information of this point and the average counting rate from the 31st s to the 60th s;

[0097] Compare the average counting rates of the three points (-2.2, 0.0), (-2.1, 0.0), and (-2.3, 0.0).

[0098] Assume that the average counting rate at the point (-2.2, 0.0) is the largest. Move to this coordinate point, and use this coordinate point as the starting point for the next move. Clear the information of the two coordinate points (-2.0, 0.0) and (-1.8, 0.0).

[0099] Since the current d x = 0.1 mm, the X-axis motor has reached the minimum step. The last point (-2.2, 0.0) is determined as the position closest to the focus. Modify dx = 0.0 mm, indicating that the X-axis motor has found the coordinate point closest to the focal point. Then it moves to the origin (0.0, 0.0) and starts the search in the Y-axis direction.

[0100] Due to the above technical solution, the present invention can control the XY-axis motors through the controller to move the X-ray tube. At the same time, it determines whether the line connecting the focal point of the X-ray tube and the center point of the hole of the collimator is perpendicular to the flange plane of the X-ray tube according to the data sampled by the detector, forming a closed-loop feedback control system. After alignment, the flange of the collimator and the X-ray tube is locked, and other characteristics of the X-ray tube are continuously tested. After the present invention is put into use and the quality inspection of the X-ray tube is more stringent, the failure rate of the X-ray tube in the future will be greatly reduced.

[0101] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An automatic X-ray tube focal point positioning device, characterized in that, Comprising: A controller, an XY-axis moving platform, a Z-axis moving platform, an X-ray tube mounted on the XY-axis moving platform, and a detector and a collimator mounted on the Z-axis moving platform. The XY-axis moving platform includes an X-axis motor and a Y-axis motor for adjusting the X-ray tube to find the focal position. The Z-axis moving platform includes a Z-axis motor for moving the detector up and down to facilitate the disassembly and assembly of the X-ray tube; The controller controls the X-axis motor, Y-axis motor, and Z motor in the following manner to achieve automatic positioning of the X-ray tube focal point, including: Set d x is the distance between the previous position and the moved position of the X-axis motor, d y is the distance between the previous position and the moved position of the Y-axis motor, x0 is the current X-axis coordinate point, and y0 represents the current Y-axis coordinate point; Move the X-axis motor and Y-axis motor to the origin of coordinates and perform a test operation, where the test operation includes: lowering the Z-axis to the test position for a 60s test and saving the count rate per second, saving the coordinate information of this test position and the average count rate from the 31st to 60th second after the test is completed, and initializing d x and d y are initial values not equal to zero respectively; Step 1, determine whether d x is equal to 0. If not, move the X-axis motor to execute loop A; if so, it means that the movement in the X-axis direction has ended. Move the X-ray tube to the origin of coordinates, execute the said test operation, and then start moving the Y-axis motor to execute loop B, where the origin of coordinates (0.0, 0.0) is the position where the physical center of the X-ray tube flange coincides with the center of the collimator; Step 2, after the end of loop B, according to the final coordinate point (x0, 0.0) obtained from loop A and the final coordinate point (0.0, y0) obtained from loop B, the intersection coordinate of these two points is obtained as (x0, y0), and finally this point is determined as the focal point of the X-ray tube; Among them, the loop A includes: Step A1: Determine whether, after moving a distance of d in the positive X-axis direction from the current coordinate point, it will exceed the positive X-axis limit coordinate point used to prevent mechanical collisions. If so, the X-axis motor moves a first distance D1 in the positive direction, where D1 = positive X-axis limit coordinate point - x0. If not, the X-axis motor moves a distance of d x ; After moving into place, perform the test operation x ; After moving into place, perform the test operation; Step A2, determine whether it will exceed the negative X limit coordinate point used to prevent mechanical collision after moving 2d in the negative X-axis direction from the current coordinate point. If not, the X-axis motor moves 2d in the negative direction x distance. If so, the X-axis motor moves a second distance D2 in the negative direction, where D2 = x0 + |negative X limit coordinate point|; after moving in place, perform the test operation; x distance Step A3, compare the average count rates of the three point positions obtained from the nearest three test operations in the X-axis direction, save the coordinate point position information with the largest average count rate and move to this point position, and at the same time clear the other two groups of data; Step A4, determine the current moving distance d x whether it is equal to the first predetermined value. If not, halve d x and return to Step 1 to continue executing Loop A; if so, set d x to 0; Among them, the loop B includes: Step B1: Determine whether, after moving the current coordinate point in the positive Y-axis direction by a distance d y it will exceed the positive Y-axis limit coordinate point used to prevent mechanical collisions. If so, the X-axis motor moves in the positive direction by a third distance D3, where D3 = positive Y-axis limit coordinate point - y0. Otherwise, the Y-axis motor moves in the positive direction by a distance d y ; after moving into place, perform the test operation; Step B2: Determine whether, after moving 2d in the negative Y-axis direction from the current coordinate point, it will exceed the negative Y-axis limit coordinate point used to prevent mechanical collisions. If so, the Y-axis motor moves 2d in the negative direction y distance; otherwise, the X-axis motor moves a fourth distance D4 in the negative direction, where D4 = y0 + |negative Y-axis limit coordinate point|. After moving into place, perform the test operation y ; Step B3, compare the average count rates of the three point positions obtained from the nearest three test operations in the Y-axis direction, save the coordinate point position information with the largest average count rate and move to this point position, and at the same time clear the other two groups of data; Step B4, determine the current moving distance d y Whether it is equal to the second predetermined value. If not, halve d y and return to Step 1 to continue executing loop B; if so, set d y to 0.

2. The X-ray tube focus automatic positioning device according to claim 1, wherein Both the first predetermined value and the second predetermined value are 0.1 mm.

3. The X-ray tube focus automatic positioning device according to claim 1, characterized in that, After the controller moves the X-ray tube to the coordinate point (x0, y0), according to the Pythagorean theorem a 2 + b 2 = c 2 Determine whether the distance from (x0, y0) to the coordinate origin (0.0, 0.0) is less than or equal to 2 mm. If so, it is determined that the focus position of the X-ray tube is qualified, and the focus positioning test is ended. Otherwise, it is determined that the focus position of the X-ray tube is unqualified, and all current tests are ended.