A laser alignment line coaxial calibration device and method for a radiotherapy device

Abstract

This invention relates to a coaxial calibration device and method for laser indicator lines in radiotherapy equipment, belonging to the technical field of radiotherapy equipment. The coaxial calibration device includes: a primary collimator and a multi-leaf collimator connected together; a laser indicator light mounted on a multi-degree-of-freedom adjustment device, which is also mounted on the multi-leaf collimator, which contains a reflecting mirror; a positioning seat connected to the multi-leaf collimator; a cylindrical calibration fixture and a target ball mounted on the positioning seat, with the cylindrical calibration fixture coaxial with the primary collimator; a laser tracker working in conjunction with the target ball to measure the positions of the primary collimator and the cylindrical calibration fixture; and the laser indicator light being activated, and the laser indicator line emitted by the laser indicator light being reflected by the reflecting mirror and then passing through the cylindrical calibration fixture by adjusting the multi-degree-of-freedom adjustment device. This device can accurately acquire the straightness and coaxiality data of the laser line, and the data is traceable and verifiable, improving alignment accuracy.

Description

Technical Field

[0001] This invention relates to a coaxial calibration device and method for laser indicator lines in radiotherapy equipment, belonging to the technical field of radiotherapy equipment. Background Technology

[0002] In clinical radiotherapy equipment, the laser indicator line is used to accurately indicate the center of the X-ray beam. Its coaxiality with the mechanical center of the equipment directly determines the positioning accuracy of the radiotherapy target area, thus affecting the efficacy and safety of radiotherapy. The laser indicator is usually installed on a multi-degree-of-freedom adjustment device. After being reflected by a 45° reflecting mirror, the laser forms a vertically downward indicator light (spot diameter of 0.5 mm) used to locate the radiotherapy target area.

[0003] Current methods for calibrating the coaxiality of the laser line and the mechanical center rely heavily on operator visual observation, simple alignment plate comparison, or dial indicator measurement. The accuracy of these methods depends on human experience, making it impossible to quantitatively determine the coaxiality deviation between the laser line and the mechanical center. This is highly subjective and prone to significant errors. Furthermore, the lack of a unified calibration benchmark prevents effective correlation between the laser line alignment and the equipment's mechanical center and primary collimator center, leading to unreliable calibration results. It also fails to verify long-distance laser line skewness, only verifying alignment at local points, and cannot reflect the straightness and coaxiality of the laser line throughout its entire length. Without standardized calibration procedures and data evaluation methods, calibration results vary significantly between different operators and in different calibration scenarios, resulting in poor repeatability and failing to meet the calibration requirements for mass production and large-scale installation.

[0004] Therefore, there is an urgent need for a device and method that can achieve coaxial calibration of the laser indicator line of radiotherapy equipment. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a coaxial calibration device and method for laser indicator lines in radiotherapy equipment. This device provides a unified calibration standard, effectively linking the laser line alignment with the equipment's mechanical center and the primary collimator center. It reflects the straightness and coaxiality of the laser line throughout its entire trajectory, avoiding significant differences in calibration results between different operators in different calibration scenarios, and ensuring repeatability of the calibration.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a coaxial calibration device for a laser indicator line in a radiotherapy device, comprising: A primary collimator and a multi-leaf collimator, wherein the primary collimator is connected to the multi-leaf collimator via a connector; A laser indicator light is mounted on a multi-degree-of-freedom adjustment device, which is mounted on the connector, and a reflective lens is also mounted on the connector. The positioning seat is connected to the multi-leaf collimator; A cylindrical calibration fixture and a target ball are mounted on the positioning seat, and the cylindrical calibration fixture is coaxial with the primary collimator. A laser tracker, in conjunction with the target ball, measures the position of the primary collimator and the cylindrical calibration fixture. The laser indicator light is turned on, and the laser indicator line emitted by the laser indicator light is reflected by the reflective lens and passes through the cylindrical calibration fixture by adjusting the multi-degree-of-freedom adjustment device. The coaxiality of the laser indicator line and the mechanical center reference axis of the equipment is calibrated by the real-time output of the laser tracker and the target ball detection value.

[0007] In one embodiment of the present invention, the cylindrical calibration fixture includes a first hole and a second hole, wherein the diameter of the first hole is smaller than the diameter of the second hole, and the formula for calculating the diameter of the first hole is as follows: D p =D1+2×Δ max (1) In the formula: D p D1 is the diameter of the first hole, in mm; D1 is the diameter of the laser spot of the laser indicator line, in mm; Δ max The maximum permissible coaxiality deviation is expressed in mm.

[0008] In one embodiment of the present invention, the length of the cylindrical calibration fixture is calculated using the following formula: L = K × SAD × tanθ max (2) In the formula: L is the effective length of the cylindrical calibration device, in mm; K is the safety factor, generally taken as 1.2~1.5; SAD is the source center distance, in mm; θ max This represents the maximum permissible deflection angle for the laser.

[0009] In one embodiment of the present invention, the coaxiality between the outer circle and the inner hole of the cylindrical calibration fixture is ≤0.01mm, and the coaxiality between the cylindrical calibration fixture and the primary collimator is ≤0.02mm.

[0010] In one embodiment of the present invention, the cylindrical calibration device is connected to the positioning seat by a thread, and the positioning seat adjusts the cylindrical calibration device by a four-dimensional adjustment bracket and a set screw, and is self-locked by the thread.

[0011] In one embodiment of the present invention, the tilt angle of the reflective lens is 45°, and the center of the reflective lens is coaxial with the axis of the primary collimator.

[0012] Secondly, the present invention provides a method for coaxial calibration of a laser indicator line in a radiotherapy device, using the aforementioned coaxial calibration device for a laser indicator line in a radiotherapy device. The calibration method includes the following steps: Step 1: Assembly of the calibration device; Install the laser indicator light on the multi-degree-of-freedom adjustment device, with the reflector tilted at 45° so that the laser indicator line can be emitted vertically downwards after being reflected by the reflector; Install the cylindrical calibration fixture on the positioning seat, which is then installed on the multi-leaf collimator. Adjust the position of the positioning seat to ensure that the mounting surface of the positioning seat is in close contact with the reference surface at the lower end of the multi-leaf collimator. Install the laser tracker and the target ball, and adjust the laser tracker to normal working condition. Step 2: Establish the mechanical center reference axis; using the laser tracker in conjunction with the target ball, perform multi-point measurements on the inner hole of the primary collimator, and obtain the central axis of the primary collimator through data fitting, and use this axis as the mechanical center reference axis of the equipment; Step 3: Coaxial positioning of the cylindrical calibration fixture; using the laser tracker in conjunction with the target ball, perform multi-point scanning measurements on the outer cylindrical surface of the cylindrical calibration fixture, and obtain the central axis of the cylindrical calibration fixture through data fitting; by finely adjusting the position of the positioning seat, make the central axis of the cylindrical calibration fixture coaxial with the central axis of the primary collimator established in Step 2, and after adjustment, make its coaxiality ≤0.02mm, lock the position of the cylindrical calibration fixture, and complete the coaxial positioning of the cylindrical calibration fixture; Step 4: Adjusting the position of the laser indicator line; turn on the laser indicator light so that the laser indicator line shines vertically downwards after being reflected by the reflective lens; adjust the illumination angle and position of the laser indicator line by adjusting the multi-degree-of-freedom adjustment device so that the laser indicator line completely passes through the inner hole of the cylindrical calibration fixture and emerges from the lower end face of the cylindrical calibration fixture; during the adjustment process, manually coarsely adjust the light spot into the inner hole of the cylindrical calibration fixture, and the laser tracker outputs the deviation value in real time, and then performs quantitative fine adjustment based on the displayed deviation value; Step 5: Evaluation of calibration results. The calibration results are evaluated according to the standard. If all conditions are met, the calibration is deemed qualified.

[0013] In one embodiment of the present invention, in step two, since the inner diameter of the primary collimator is small and cannot be directly sampled, the central axis is obtained by using an equivalent inner diameter with an outer circle. The method for using an equivalent inner diameter with an outer circle is as follows: 1) Sampling object: Perform multi-point sampling at equal angles on the outer cylindrical surface of the primary collimator, collecting at least 8 points; 2) Outlier Removal: Outliers are removed using the 3σ principle to prevent surface defects from affecting the baseline; 3) Least square fitting of spatial cylindrical surface: Fit the central axis of the outer circle using the equation of the spatial cylinder as a constraint; 4) Equivalent inner hole axis: When the coaxiality between the inner and outer circles of the primary collimator is ≤0.005mm, the outer circle axis is directly equivalent to the inner hole center axis, serving as the mechanical center reference axis of the equipment.

[0014] In one embodiment of the present invention, in step three, when sampling and data fitting, at least three cross sections are taken along the axial direction of the cylindrical calibration fixture, and at least six points are sampled from the outer circle of each cross section, and the center of each cross section is fitted respectively; spatial straight line fitting is performed on the center of the multi-section circle, and the coaxiality of the cylindrical calibration fixture itself is introduced for weighted correction to obtain the high-precision axis of the cylindrical calibration fixture.

[0015] In one embodiment of the present invention, the evaluation criteria in step five are as follows: S1. The laser pointer line can pass smoothly through the inner hole of the cylindrical calibration fixture without obstruction or obvious offset; S2. The laser tracker confirms that the outer circle of the cylindrical calibration fixture is coaxial with the central axis of the primary collimator and meets the coaxiality requirement. S3. The laser tracker confirms that the coaxiality of the laser indicator line and the mechanical center reference axis meets the design specifications, i.e., coaxiality ≤ 0.05mm.

[0016] The beneficial effects of this invention are: The present invention provides a coaxial calibration device and method for laser indicator lines in radiotherapy equipment, which has the following advantages: 1. The coaxial calibration device for laser indicator lines in radiotherapy equipment provided by this invention has a simple structure and high precision. Through a high-precision coaxial design of the inner and outer circles of the cylindrical calibration fixture, the 0.56mm inner hole precisely matches the 0.5mm diameter of the laser spot, serving as a visual centering reference. Combined with a laser tracker, it enables quantitative measurement, accurately acquiring the straightness and coaxiality data of the laser line. This data is traceable and verifiable, effectively avoiding errors from manual visual observation and improving centering accuracy. Furthermore, the calibration method provided by this invention achieves consistency between the laser line alignment and the mechanical center of the equipment and the center of the primary collimator, solving the problem of inconsistent calibration references in existing systems.

[0017] 2. This coaxial calibration device for laser indicator lines in radiotherapy equipment, through the reasonable design of the length of the cylindrical fixture, can effectively verify the straightness and skewness of the laser line throughout its entire path, ensuring that the laser line is coaxial with the mechanical center throughout the entire irradiation range.

[0018] 3. This coaxial calibration method for laser indicator lines in radiotherapy equipment features a standardized and highly adaptable process. It clearly defines the complete workflow from device assembly and benchmark establishment to coarse calibration, fine calibration, and result evaluation. The calibration process is repeatable and reproducible, suitable for mass production calibration and large-scale installation calibration of radiotherapy equipment, improving calibration efficiency and consistency. It avoids the problems of significant differences in calibration results among different operators and in different calibration scenarios, resulting in poor calibration repeatability and failing to meet the needs of mass production and large-scale installation calibration. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a front view of the radiotherapy device provided by the present invention.

[0021] Figure 2 This is a perspective view of the radiotherapy device provided by the present invention.

[0022] Figure 3 This is a perspective view of the coaxial calibration device for laser indicator lines in radiotherapy equipment provided by the present invention.

[0023] Figure 4 This is a perspective view of the cylindrical calibration fixture provided by the present invention.

[0024] Figure 5 This is a cross-sectional view of the cylindrical calibration fixture provided by the present invention.

[0025] Figure 6 This is a perspective view of the laser tracker provided by the present invention.

[0026] Figure 7 This is a flowchart of the calibration method provided by the present invention.

[0027] In the diagram: 1. Laser indicator light; 2. Multi-degree-of-freedom adjustment device; 3. Reflecting mirror; 4. Primary collimator; 5. Cylindrical calibration fixture; 51. First hole; 52. Second hole; 6. Laser indicator line; 7. Target ball; 8. Positioning seat; 9. Laser tracker; 10. Multi-leaf collimator; 11. Connecting component. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0031] like Figures 1 to 7As shown, this invention provides a coaxial calibration device for a laser indicator line in a radiotherapy device. The device includes a laser indicator light 1, a multi-degree-of-freedom adjustment device 2, a primary collimator 4, a cylindrical calibration fixture 5, and a positioning seat 8. The primary collimator 4 is mounted on the radiotherapy device. A multi-leaf collimator 10 is provided on one side of the primary collimator 4. The primary collimator 4 is connected to the multi-leaf collimator 10 via a connector 11. The multi-leaf collimator 10 is a core component of the radiotherapy device, composed of dozens of pairs of independently driven metal blades, capable of precisely shaping the radiation beam to match the shape of the tumor target area, achieving precise radiotherapy. The laser beam emitted by the laser indicator light 1 is the laser indicator line 6. The laser indicator light 1 is mounted on the multi-degree-of-freedom adjustment device 2, and the two are connected by threads. The multi-degree-of-freedom adjustment device 2 is mounted on the connector 11. The multi-degree-of-freedom adjustment device 2 can realize multi-directional adjustment of the laser indicator light 1 (rotation, up / down, left / right), and can be used to adjust the irradiation angle and position of the laser indicator line 6, achieving coarse and fine calibration of the laser indicator line 6. The reflector 3 is mounted on the connector 11. The center of the reflector 3 must be coaxial with the axis of the primary collimator 4 and tilted at 45°. Adjust the angle of the laser indicator 1 so that the laser indicator line 6 is reflected vertically downward after being reflected by the reflector 3. At SAD 800mm, ensure that the diameter of the laser spot is 0.5mm after focusing.

[0032] In some embodiments, the positioning seat 8 is installed below the multi-leaf collimator 10. The position of the positioning seat 8 is adjusted to ensure that the mounting surface of the positioning seat 8 is in close contact with the lower reference surface of the multi-leaf collimator 10. One end of the cylindrical calibration fixture 5 is connected to the side of the positioning seat 8 away from the multi-leaf collimator 10 by a thread, ensuring that the cylindrical calibration fixture 5 is accurately positioned and firmly installed. The positioning seat 8 can finely adjust the position of the cylindrical calibration fixture 5 to ensure that the central axis of the cylindrical calibration fixture 5 is coaxial with the mechanical central reference axis. After adjustment, it can be locked to ensure that the position of the fixture is stable during the calibration process. When not performing coaxial calibration of the laser indicator line, the cylindrical calibration fixture 5 can be removed. The target ball 7 and the laser tracker 9 are existing equipment and can be used independently. When using them, the operator only needs to fix the laser tracker 9 with a tripod or bracket first, and then hold the target ball 7 against the positioning seat 8. The target ball 7 is used in conjunction with the laser tracker 9 for measurement to assist in measuring the spatial coordinates of the outer circle of the primary collimator 4 and the outer circle of the cylindrical calibration fixture 5, thereby improving measurement accuracy. The laser tracker 9 can be used for quantitative measurement, and can accurately measure the inner hole of the primary collimator 4, the outer circle of the cylindrical calibration fixture 5, and the spatial position of the laser indicator line 6. The center axis of each component is obtained through data fitting, and the coaxiality and straightness are accurately detected.

[0033] Specifically, in this embodiment, the positioning seat 8 is provided with a four-dimensional adjustment frame, a set screw, a thread and other structures. The position of the cylindrical calibration fixture 5 can be adjusted by the micro four-dimensional adjustment frame, and the cylindrical calibration fixture 5 can be fine-tuned by the set screw. After adjustment, it can be locked by the self-locking thread.

[0034] In some embodiments, the cylindrical calibration fixture 5 includes a first hole 51 and a second hole 52, the diameter of the first hole 51 being smaller than the diameter of the second hole 52. The laser indicator line 6, after being reflected by the reflective lens 3, can pass sequentially through the second hole 52 and the first hole 51 of the cylindrical calibration fixture 5. The outer circle and inner hole of the cylindrical calibration fixture 5 are machined using a high-precision coaxial machining method, with a coaxiality ≤0.01mm, ensuring the accuracy of the fixture's own reference. The length is designed according to the requirements for verifying long-distance laser line deviation, effectively detecting the straightness of the laser line throughout its entire path. The fixture mounting surface can be tightly fitted with the mechanical reference surface of the equipment, avoiding installation deviations.

[0035] In some embodiments, the aperture size of the first hole 51 of the cylindrical calibration device 5 is determined based on the spot diameter of the laser indicator line 6, and the calculation formula is as follows: D p =D1+2×Δ max (1) In the formula: D p D1 is the diameter of the first hole 51 in cylindrical calibration fixture 5, in mm; D1 is the diameter of the laser spot, in mm; Δ max The maximum permissible coaxiality deviation is expressed in mm, typically 0.03 mm.

[0036] In some embodiments, the length design of the cylindrical calibration device 5 is also crucial. When the length of the cylindrical calibration device 5 is too long, the cylindrical calibration fixture 5 will sag under its own weight, causing the installation to tilt and significantly reducing its stability. When the length of the cylindrical calibration device 5 is too short, it can only verify a single point and cannot detect long-distance deviations, leading to a higher misjudgment rate of coaxiality. The formula for calculating the length of the cylindrical calibration device 5 is as follows: L = K × SAD × tanθ max (2) In the formula: L is the effective length of the cylindrical calibration device 5, in mm; K is the safety factor, generally taken as 1.2~1.5; SAD is the source center distance, in mm; θ max This represents the maximum permissible deflection angle of the laser, expressed in degrees.

[0037] Specifically, in this embodiment, θ max The value is typically 0.002°.

[0038] In addition, such as Figure 5As shown, the present invention also provides a method for coaxial calibration of a laser indicator line in a radiotherapy device, using the aforementioned coaxial calibration device for a laser indicator line in a radiotherapy device. The calibration method includes the following steps: Step 1: Assembly of the calibration device. Install the laser indicator light 1 on the multi-degree-of-freedom adjustment device 2. The reflector 3 is tilted at 45° so that the laser indicator line 6, after being reflected by the reflector 3, can be emitted vertically downwards. Install the cylindrical calibration fixture 5 on the positioning seat 8. The positioning seat 8 is installed on the multi-leaf collimator 10. Adjust the position of the positioning seat 8 to ensure that the mounting surface of the positioning seat 8 is in close contact with the reference surface at the lower end of the multi-leaf collimator 10. The laser tracker 9 is fixed with a bracket. Hold the target ball 7 against the positioning seat 8 and adjust the laser tracker 9 to normal working condition, ensuring that its measurement accuracy meets the calibration requirements.

[0039] Step 2: Establish the mechanical center reference. Using a laser tracker 9 in conjunction with a target ball 7, multi-point measurements are performed on the inner hole of the primary collimator 4. The central axis of the primary collimator 4 is obtained through data fitting. This axis is used as the mechanical center reference axis of the equipment, providing a unified and reliable reference basis for subsequent calibration.

[0040] Step 3: Coaxial positioning of the cylindrical calibration fixture. Using a laser tracker 9 in conjunction with a target ball 7, multi-point scanning measurements are performed on the outer cylindrical surface of the cylindrical calibration fixture 5. The central axis of the cylindrical calibration fixture 5 is obtained through data fitting. By fine-tuning the position of the positioning seat 8, the central axis of the cylindrical calibration fixture 5 is made coaxial with the central axis of the primary collimator 4 established in Step 2. After adjustment, the coaxiality is ≤0.02mm. The fixture position is then locked, completing the coaxial positioning of the fixture.

[0041] During sampling and data fitting, at least three cross sections are taken along the axis of the cylindrical calibration fixture 5. At least six points are sampled from the outer circle of each cross section, and the center of each cross section is fitted. Spatial straight line fitting is performed on the center of the multi-section cross sections, and the coaxiality (≤0.01mm) of the cylindrical calibration fixture 5 itself is introduced for weighted correction to obtain the high-precision fixture axis.

[0042] Step 4: Adjusting the position of the laser indicator line. Turn on the laser indicator light 1 so that the laser indicator line 6 shines vertically downwards after being reflected by the reflective lens 3. Adjust the illumination angle and position of the laser indicator line 6 by adjusting the multi-degree-of-freedom adjustment device 2, so that the laser indicator line 6 completely passes through the first hole 51 and the second hole 52 of the cylindrical calibration fixture 5 and emerges from the lower end face of the cylindrical calibration fixture 5. During the adjustment process, the light spot is introduced into the first hole 51 and the second hole 52 of the cylindrical calibration fixture 5 by manual coarse adjustment. The laser tracker 9 outputs the deviation value in real time, and quantitative fine adjustment is then performed based on the displayed deviation value.

[0043] Observe the state where the laser indicator line 6 passes through the first hole 51 and the second hole 52 of the cylindrical calibration tool 5, ensure that the laser indicator line 6 can stably pass through the first hole 51 and the second hole 52 of the cylindrical calibration tool 5 without obstruction or deviation, so as to complete the calibration of the laser indicator line 6.

[0044] Step 5: Evaluation of calibration results. After the calibration is completed, evaluate the calibration result according to the following criteria, and the calibration is judged as qualified if all conditions are met: S1, the laser indicator line 6 can smoothly pass through the first hole 51 and the second hole 52 of the cylindrical calibration tool 5, without obstruction and obvious deviation; S2, detection by the laser tracker 9 confirms that the outer circle of the cylindrical calibration tool 5 is coaxial with the central axis of the primary collimator 4, meeting the coaxiality requirement; S3, detection by the laser tracker 9 confirms that the coaxiality between the axis of the laser indicator line and the mechanical center reference axis meets the design index (usually required to be ≤ 0.05mm).

[0045] Specifically, in step 2, since the inner hole aperture of the primary collimator 4 is too small to allow direct sampling, the method of equivalent inner hole via outer circle is adopted to obtain the central axis. The method of equivalent inner hole via outer circle is as follows: 1) Sampling object: perform equal-angle multi-point sampling (≥ 8 points) on the outer cylindrical surface of the primary collimator 4; 2) Outlier elimination: the 3σ principle is used to eliminate abnormal points to avoid the influence of surface defects on the reference; 3) Least square fitting of spatial cylindrical surface: the central axis of the outer circle is fitted constrained by the spatial cylindrical equation; 4) Equivalent inner hole axis: since the coaxiality of the inner circle / outer circle of the primary collimator 4 has been guaranteed to be ≤ 0.005mm during processing, the outer circle axis can be directly equivalent to the inner hole central axis, which is used as the mechanical center reference axis of the equipment.

[0046] Wherein, the principle of fitting the central axis of the outer circle constrained by the spatial cylindrical equation is as follows: the unit vector in the axis direction is (a, b, c), which determines the orientation of the cylinder, and a point on the axis is (x0, y0, z0), which is used to determine the spatial position of the axis. The radius of the cylinder is r. According to the fact that the distance from any point Pi(x i , y i , z i ) on the cylindrical surface to the axis must be equal to the radius r, the geometric constraint is: [c(y i - y0) - b(z i - z0)] 2 + [a(z i - z0) - c(x i - x0)] 2 + [b(xi - x0) - a(y i -y0)] 2 = r 2 (3) Example 1 This embodiment uses the aforementioned coaxial calibration device and method for laser indicator lines in radiotherapy equipment. The specific implementation process is as follows: 1. Preparation of calibration device: Prepare cylindrical calibration fixture 5, wherein the diameter of the laser spot is 0.5 mm, and the diameter of the first hole 51 is 0.56 mm, and its outer diameter is 20 mm, according to formula (1). SAD is 800 mm, θ max Taking 0.002°, according to formula (2), the length of the cylindrical calibration fixture 5 is 60mm. The coaxiality between the inner hole and the outer circle is 0.008mm. Assemble the positioning seat 8, the laser tracker 9 and the target ball 7, and adjust the laser tracker 9 to normal working condition; adjust the laser indicator 1 to emit the laser indicator line 6, and adjust the spot diameter of the laser indicator line 6 to 0.5mm.

[0047] 2. Installation of the device: Install the laser indicator 1 on the multi-degree-of-freedom adjustment device 2. The reflection angle of the reflector 3 is 45°, so that the laser indicator line 6 is reflected vertically downward after being reflected by the reflector 3. Install the cylindrical calibration fixture 5 on the positioning seat 8 and place the positioning seat 8 below the multi-leaf collimator 10, ensuring that the mounting surface of the positioning seat 8 is in close contact with the reference surface at the lower end of the multi-leaf collimator 10.

[0048] 3. Establishing the mechanical center reference: Using a laser tracker 9 in conjunction with a target ball 7, the primary collimator 4 is modeled as an equivalent inner hole with an outer circle. Multiple points at equal angles are sampled on its outer cylindrical surface to eliminate outliers. The center line of the outer circle is fitted using least squares, and the outer circle axis is modeled as the center axis of the inner hole, serving as the mechanical center reference axis of the equipment.

[0049] 4. Coaxial positioning of cylindrical calibration fixture: The outer cylindrical surface of the fixture is measured by laser tracker 9 and the central axis of cylindrical calibration fixture 5 is fitted. By fine-tuning the position of positioning seat 8, the coaxiality between the axis of cylindrical calibration fixture and the mechanical center reference axis is adjusted to 0.015mm, and cylindrical calibration fixture 5 is locked.

[0050] 5. Laser indicator line calibration: Turn on the laser indicator light 1, and adjust the deflection, up and down and left and right angles of the multi-degree-of-freedom adjustment device 2 so that the laser indicator line 6 with a spot diameter of 0.5mm can completely pass through the first hole 51 and stably emerge from the lower end face of the cylindrical calibration device 5 without obstruction or offset.

[0051] 6. Result evaluation: The laser indicator line 6 can pass smoothly through the first hole 51 and the second hole 52 in the cylindrical calibration fixture 5. The outer circle of the cylindrical calibration device 5 is coaxial with the primary collimator 4. The coaxiality of the laser indicator line 6 with the mechanical center is 0.022mm, which is less than 0.05mm. This meets the equipment design specifications, and the calibration is deemed qualified.

[0052] This embodiment achieves high-precision coaxial calibration of the laser indicator line with a spot diameter of 0.5mm and the mechanical center of the equipment through the above-mentioned calibration device and method. The calibration process is standardized and the data is traceable, which effectively solves the problems of low accuracy and poor repeatability of existing calibration methods and is suitable for the installation calibration requirements of this model of radiotherapy equipment.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A coaxial calibration device for a laser indicator line in a radiotherapy device, characterized in that, include: A primary collimator (4) and a multi-leaf collimator (10), wherein the primary collimator (4) is connected to the multi-leaf collimator (10) via a connector (11); Laser indicator (1), the laser indicator (1) is mounted on the multi-degree-of-freedom adjustment device (2), the multi-degree-of-freedom adjustment device (2) is mounted on the connector (11), and the connector (11) is also mounted with a reflective lens (3). The positioning seat (8) is connected to the multi-leaf collimator (10); A cylindrical calibration fixture (5) and a target ball (7) are mounted on the positioning seat (8), and the cylindrical calibration fixture (5) is coaxial with the primary collimator (4); The laser tracker (9) works in conjunction with the target ball (7) to measure the position of the primary collimator (4) and the cylindrical calibration fixture (5); Turn on the laser indicator (1), and adjust the multi-degree-of-freedom adjustment device (2) so that the laser indicator line (6) emitted by the laser indicator (1) is reflected by the reflective lens (3) and passes through the cylindrical calibration fixture (5). The coaxiality of the laser indicator line (6) and the mechanical center reference axis of the equipment is calibrated by the real-time output of the detection values ​​of the laser tracker (9) and the target ball (7).

2. The coaxial calibration device for laser indicator lines in radiotherapy equipment according to claim 1, characterized in that, The cylindrical calibration fixture (5) includes a first hole (51) and a second hole (52). The diameter of the first hole (51) is smaller than the diameter of the second hole (52). The formula for calculating the diameter of the first hole (51) is as follows: D p =D1+2×Δ max (1) In the formula: D p D1 is the diameter of the first hole (51) in mm; D1 is the diameter of the laser spot of the laser indicator line (6) in mm; Δ max The maximum permissible coaxiality deviation is expressed in mm.

3. The coaxial calibration device for laser indicator lines in radiotherapy equipment according to claim 2, characterized in that, The formula for calculating the length of the cylindrical calibration fixture (5) is as follows: L= K× SAD × tanθ max (2) In the formula: L is the effective length of the cylindrical calibration device (5), in mm; K is the safety factor, generally taken as 1.2~1.5; SAD is the source center distance, in mm; θ max This represents the maximum permissible deflection angle for the laser.

4. The coaxial calibration device for laser indicator lines in radiotherapy equipment according to claim 3, characterized in that, The coaxiality between the outer circle and the inner hole of the cylindrical calibration fixture (5) is ≤0.01mm, and the coaxiality between the cylindrical calibration fixture (5) and the primary collimator (4) is ≤0.02mm.

5. The coaxial calibration device for laser indicator lines in radiotherapy equipment according to claim 1, characterized in that, The cylindrical calibration device (5) is connected to the positioning seat (8) by a thread. The positioning seat (8) adjusts the cylindrical calibration device (5) by a four-dimensional adjustment frame and a set screw, and is self-locked by the thread.

6. The coaxial calibration device for laser indicator lines in radiotherapy equipment according to claim 1, characterized in that, The tilt angle of the reflective lens (3) is 45°, and the center of the reflective lens (3) is coaxial with the axis of the primary collimator (4).

7. A method for coaxial calibration of a laser indicator line in a radiotherapy device, characterized in that, The laser indicator line coaxial calibration device for radiotherapy equipment according to any one of claims 1-6 is used, wherein the calibration method includes: Step 1: Assembly of the calibration device; Install the laser indicator (1) on the multi-degree-of-freedom adjustment device (2), and tilt the reflector (3) at 45° so that the laser indicator line (6) can be emitted vertically downward after being reflected by the reflector (3); Install the cylindrical calibration fixture (5) on the positioning seat (8), and install the positioning seat (8) on the multi-leaf collimator (10). Adjust the position of the positioning seat (8) to ensure that the mounting surface of the positioning seat (8) is in close contact with the reference surface at the lower end of the multi-leaf collimator (10), and install the laser tracker (9) and the target ball (7). Debug the laser tracker (9) to normal working condition; Step 2: Establish the mechanical center reference axis; using the laser tracker (9) in conjunction with the target ball (7), perform multi-point measurements on the inner hole of the primary collimator (4), and obtain the central axis of the primary collimator (4) through data fitting, and use this axis as the mechanical center reference axis of the equipment; Step 3: Coaxial positioning of the cylindrical calibration fixture; using the laser tracker (9) in conjunction with the target ball (7), multi-point scanning measurement is performed on the outer cylindrical surface of the cylindrical calibration fixture (5), and the central axis of the cylindrical calibration fixture (5) is obtained through data fitting; by finely adjusting the position of the positioning seat (8), the central axis of the cylindrical calibration fixture (5) is made coaxial with the central axis of the primary collimator (4) established in Step 2, and after adjustment, its coaxiality is ≤0.02mm, the position of the cylindrical calibration fixture (5) is locked, and the coaxial positioning of the cylindrical calibration fixture (5) is completed; Step 4: Adjusting the position of the laser indicator line; turn on the laser indicator (1) so that the laser indicator line (6) is reflected vertically downward after being reflected by the reflective lens (3); adjust the irradiation angle and position of the laser indicator line (6) by adjusting the multi-degree-of-freedom adjustment device (2) so that the laser indicator line (6) completely passes through the inner hole of the cylindrical calibration fixture (5) and emerges from the lower end face of the cylindrical calibration fixture (5); during the adjustment process, the light spot is introduced into the inner hole of the cylindrical calibration fixture (5) by manual coarse adjustment, and the laser tracker (9) outputs the deviation value in real time, and then performs quantitative fine adjustment based on the displayed deviation value; Step 5: Evaluation of calibration results. The calibration results are evaluated according to the standard. If all conditions are met, the calibration is deemed qualified.

8. The method for coaxial calibration of laser indicator lines for radiotherapy equipment according to claim 7, characterized in that, In step two, since the inner diameter of the primary collimator (4) is small and cannot be directly sampled, the central axis is obtained by using the method of equivalent inner diameter of outer circle. The method of equivalent inner diameter of outer circle is as follows: 1) Sampling object: Perform equal-angle multi-point sampling on the outer cylindrical surface of the primary collimator (4), and collect at least 8 points; 2) Outlier Removal: Outliers are removed using the 3σ principle to prevent surface defects from affecting the baseline; 3) Least square fitting of spatial cylindrical surface: Fit the central axis of the outer circle using the equation of the spatial cylinder as a constraint; 4) Equivalent inner hole axis: When the coaxiality between the inner circle and the outer circle of the primary collimator (4) is ≤0.005mm, the outer circle axis is directly equivalent to the inner hole center axis, which serves as the mechanical center reference axis of the equipment.

9. The method for coaxial calibration of laser indicator lines in radiotherapy equipment according to claim 7, characterized in that, In step three, when sampling and data fitting are performed, at least three cross sections are taken along the axis of the cylindrical calibration fixture (5), and at least six points are sampled on the outer circle of each cross section, and the center of each cross section is fitted. Spatial straight line fitting is performed on the center of the multi-section circle, and the coaxiality of the cylindrical calibration fixture (5) itself is introduced for weighted correction to obtain the high-precision axis of the cylindrical calibration fixture (5).

10. The method for coaxial calibration of laser indicator lines for radiotherapy equipment according to claim 7, characterized in that, The evaluation criteria in step five are as follows: S1. The laser indicator line (6) can pass smoothly through the inner hole of the cylindrical calibration fixture (5) without obstruction or obvious offset; S2. The laser tracker (9) confirms that the outer circle of the cylindrical calibration fixture (5) is coaxial with the central axis of the primary collimator (4) and meets the coaxiality requirements. S3. The laser tracker (9) confirmed that the coaxiality of the axis of the laser indicator line (6) and the mechanical center reference axis met the design specifications, that is, the coaxiality ≤ 0.05mm.

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