Medical accelerator beam alignment test device, test method and adjustment method

Abstract

The embodiments of the present invention relate to the field of medical accelerators, and provide a medical accelerator beam centering test device, test method, and adjustment method. The device includes: a centering collimator, a first collimation hole is opened in the center, and second collimation holes are opened on both sides of the first collimation hole. The ray beam passes through the initial collimator and the centering collimator in sequence to form a radiation field; an electronic field imaging device is arranged on the side of the centering collimator away from the primary collimator, and is used to image the radiation field to obtain dose intensity distribution data. The dose intensity distribution data sets on the bed in and out direction line and the left and right direction line are respectively extracted from the dose intensity distribution data, and the offset distance and offset angle of the target center on the bed in and out direction line and the left and right direction line are calculated; the target center is adjusted based on the offset distance and offset angle of the target center on the bed in and out direction line and the left and right direction line. The centering test and adjustment of the present invention are highly accurate and reliable, and reduce product costs.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of medical accelerators, and particularly to a beam alignment test device, a test method and an adjustment method for a medical accelerator beam. Background Art

[0002] That the symmetry of the radiation field should not exceed 103% is one of the important performance indicators of medical accelerators, which is clearly required in the medical accelerator standard "Medical Accelerators - Performance and Test Methods" GB 15213-2016 5.3.1.3. To meet the symmetry requirement, it is necessary to calibrate the accelerator beam so that the hitting center coincides with the mechanical center of the treatment head, and this calibration step must be carried out both at the initial assembly stage of the accelerator beam module in the factory and after the replacement of the accelerator beam module on-site in the hospital. Currently, the calibration processes of each manufacturer are all confidential information. Among some related technologies known to those skilled in the art, an ionization chamber is used to measure the symmetry deviation, and then the direction of the beam hitting the target is controlled by a steering coil. Although this method can achieve rapid beam alignment adjustment, it also brings the following problems:

[0003] a) The above method is not applicable to accelerators without a steering coil. The current mainstream accelerators are low-energy machines (single energy ≤ 6 MV), which can cover about 85% of the market. The acceleration tubes used in low-energy machines are short, generally not exceeding 40 cm in length, and there is no steering coil system.

[0004] b) The medical accelerator itself is a very complex system. If a beam alignment control system is introduced, it will further increase the complexity of the system, increase the cost, and also increase the risk of system failure. Summary of the Invention

[0005] The purpose of the present invention is to provide at least a beam alignment test device, a test method and an adjustment method for a medical accelerator beam, which can at least solve the problem that the traditional beam alignment adjustment method is not applicable to accelerators without a steering coil, without introducing a beam alignment control system, which can lead to an increase in the complexity and cost of the system, and can reduce the risk of system failure.

[0006] To solve the above technical problems, at least one embodiment of the present invention provides a beam alignment test device for a medical accelerator, including a primary collimator, which is arranged on the direction of the beam generated at the hitting center. The device further includes:

[0007] An alignment collimator, which is arranged on the side of the primary collimator away from the hitting center, and the alignment collimator is coaxially arranged with the primary collimator. A first collimation hole is opened in the center of the alignment collimator, and second collimation holes are respectively opened on both sides of the first collimation hole. The beam passes through the initial collimator and the alignment collimator in sequence to form a radiation field;

[0008] An electronic portal imaging device is provided on the side of the centering collimator away from the primary collimator, and is used to image the radiation field to obtain dose intensity distribution data for beam centering adjustment of a medical accelerator.

[0009] In some alternative embodiments, the medical accelerator beam centering test device further includes:

[0010] A support frame for mounting and supporting the primary collimator and the centering collimator;

[0011] The bottom surface of the primary collimator is mounted on the top of the support frame, the centering collimator is mounted inside the support frame, and the electronic portal imaging device is mounted on the bottom surface of the support frame.

[0012] In some alternative embodiments, two centering lines are marked on the top of the support frame, and the two centering lines coincide with the laser lines in the in-out bed direction and the left-right direction respectively. The in-out bed direction line on the upper surface of the electronic portal imaging device coincides with the laser line in the in-out bed direction, and the left-right direction line on the upper surface of the electronic portal imaging device coincides with the laser line in the left-right direction to perform beam centering test.

[0013] At least one embodiment of the present invention further provides a method for testing the centering of a medical accelerator beam, which is implemented based on the above-mentioned medical accelerator beam centering test device; the method includes:

[0014] A ray beam is generated at the target center;

[0015] The ray beam sequentially passes through the initial collimator and the centering collimator to form a radiation field;

[0016] The electronic portal imaging device images the radiation field to obtain dose intensity distribution data for beam centering adjustment of a medical accelerator.

[0017] At least one embodiment of the present invention further provides a method for adjusting the centering of a medical accelerator beam, including:

[0018] Collect the dose intensity distribution data obtained by the electronic portal imaging device;

[0019] Respectively extract the dose intensity distribution data sets on the in-out bed direction line and the left-right direction line on the upper surface of the electronic portal imaging device from the dose intensity distribution data;

[0020] Based on the dose intensity distribution data sets on the in-out bed direction line and the left-right direction line, calculate the offset distance and offset angle of the target center on the in-out bed direction line and the left-right direction line;

[0021] Adjust the aiming center based on the offset distance and offset angle of the aiming center on the in-out bed direction line and the left-right direction line.

[0022] In some alternative embodiments, the dose intensity distribution dataset includes dose intensity data corresponding to each pixel; based on the dose intensity distribution dataset, calculating the offset distance and offset angle of the aiming center includes:

[0023] Represent the dose intensity distribution dataset as a distribution curve, with the abscissa representing the pixel and the ordinate representing the dose intensity data;

[0024] Based on the width of a single pixel, the difference in pixel widths of the radiation fields generated by the second collimator holes on the left and right sides of the first collimator hole on the distribution curve, the distance from the aiming center to the upper surface of the electronic portal imaging device, the distance from the aiming center to the bottom surface of the centering collimator, and the distance from the aiming center to the bottom surface of the primary collimator, calculate the offset distance of the aiming center;

[0025] Based on the offset distance of the radiation field center line and the distance from the aiming center to the upper surface of the electronic portal imaging device, calculate the offset angle of the aiming center.

[0026] In some alternative embodiments, to calculate the offset distance of the aiming center, the following calculation formula is used:

[0027] OO * =P*(N - M) / {2*[(h SDD -h SCD ) / h SCD -(h SDD -h SID ) / h SID}

[0028] In the formula, OO * represents the offset distance of the aiming center, h SDD represents the distance from the aiming center to the upper surface of the electronic portal imaging device, h SID represents the distance from the aiming center to the bottom surface of the centering collimator, h SCD represents the distance from the aiming center to the bottom surface of the primary collimator, P represents the width of a single pixel, N represents the pixel width of the radiation field generated by the second collimator hole on the left side of the first collimator hole on the distribution curve, and M represents the pixel width of the radiation field generated by the second collimator hole on the right side of the first collimator hole on the distribution curve.

[0029] In some alternative embodiments, to calculate the offset angle of the aiming center, the following calculation formula is used:

[0030] θ = ±arctan(|c / h SDD |)

[0031] Wherein, θ represents the offset angle of the shooting center, c represents the offset distance of the central line of the radiation field on the upper surface of the electronic portal imaging device, and h SDD represents the distance from the shooting center to the upper surface of the electronic portal imaging device.

[0032] At least one embodiment of the present invention further provides an electronic device, including:

[0033] At least one processor; and,

[0034] A memory communicatively connected to the at least one processor; wherein,

[0035] The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the above-mentioned method for adjusting the beam alignment of a medical accelerator.

[0036] At least one embodiment of the present invention further provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the above-mentioned method for adjusting the beam alignment of a medical accelerator is implemented.

[0037] The present invention provides a pair of alignment collimators to generate three parts of the radiation field, namely, the central line area and the left and right side areas, on the basis of the conical radiation field originally formed by the primary collimator. Further, the offset distances of the shooting center in the Inline and Crossline directions are calculated through the dose intensity distribution data of the radiation fields in the left and right side areas, and the offset angles of the shooting center in the Inline and Crossline directions are calculated through the dose intensity distribution data of the radiation field in the central line area. Finally, the shooting center can be adjusted according to the offset distances and offset angles in each direction to achieve the adjustment of the beam alignment of the medical accelerator. The test and adjustment accuracy only depends on the installation and positioning accuracy of the alignment collimator relative to the primary collimator. The accuracy of the alignment test and adjustment is high and reliable, without introducing additional equipment and software, reducing the product cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] One or more embodiments are illustrated by way of example in the accompanying drawings, and these exemplary illustrations do not limit the embodiments.

[0039] Figure 1 is a schematic diagram of the principle of beam alignment deviation;

[0040] Figure 2 is a schematic structural diagram of a beam alignment test device for a medical accelerator provided by an embodiment of the present invention;

[0041] Figure 3 is an imaging schematic diagram on an EPID provided by an embodiment of the present invention;

[0042] Figure 4a and Figure 4b are schematic diagrams of the centering collimator shown from different angles provided by the embodiments of the present invention;

[0043] Figure 5 is a schematic diagram of the principle of beam centering test provided by the embodiments of the present invention;

[0044] Figure 6 is a schematic diagram of the first distribution curve provided by the embodiments of the present invention;

[0045] Figure 7 is a schematic diagram of the second distribution curve provided by the embodiments of the present invention;

[0046] Figure 8 is a schematic diagram of the process flow of a method for adjusting the beam centering of a medical accelerator provided by the embodiments of the present invention;

[0047] Figure 9 is a schematic diagram of the device for adjusting the beam centering of a medical accelerator provided by the embodiments of the present invention. Detailed implementation manners

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will elaborate on each embodiment of the present invention in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in each embodiment of the present invention, many technical details are presented to help readers better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed by the present invention can still be implemented. The following division of each embodiment is for convenience of description and should not constitute any limitation to the specific implementation manner of the present invention. Each embodiment can be combined and cross-referenced with each other on the premise of no contradiction.

[0049] To facilitate the understanding of the embodiments of the present invention, the relevant content regarding the deviation of beam centering is introduced here first.

[0050] The following figure further explains the principle of beam centering deviation:

[0051] Such as Figure 1As shown, the dot represents the center of the accelerator beam hitting the target, the gray block represents the primary collimator (conical structure, and the X-ray forms a conical beam after passing through the primary collimator). The mechanical center of the primary collimator is the mechanical center of the entire accelerator system. The yellow part represents the Electronic Portal Imaging Device (EPID). The rays generated by the beam hitting the target form a radiation field of a certain shape on the EPID after passing through the primary collimator. Theoretically, the installation of the accelerator requires the coincidence of the beam hitting center and the mechanical center of the primary collimator, so that the symmetry of the radiation field can meet the regulatory requirements. However, as a very large system, the accelerator weighs several tons, and it is very difficult to ensure the coincidence of the centers during the installation process. In addition, there are also deviations in the welding of the accelerator's own target point. This requires beam alignment calibration after the accelerator is installed. When the offset distance OO * from the hitting center to the primary collimator occurs, the boundary of the radiation field collected on the EPID will correspondingly offset by the distance AA * , and AA * / OO * =(h SDD -h SCD ) / h SCD . For a conventional medical accelerator, (h SDD -h SCD ) / h SCD ≈10, and the offset of the radiation field will be magnified nearly 10 times. For example, when OO * deviates by 0.1 mm, AA * deviates by nearly 1 mm. The offset of the radiation field boundary reflects the offset of the hitting center. When the hitting center is tilted at an angle θ, the center of the radiation field is offset by CC * , where θ = ±arctan(|CC * / h SDD |). The offset of the radiation field center reflects the angular tilt of the hitting center.

[0052] To solve the above technical problems of beam alignment calibration, the present invention proposes a beam alignment test device, test method, and adjustment method for a medical accelerator. The following specifically describes the implementation details of the beam alignment test device, test method, and adjustment method provided by the present invention. The following content is only the implementation details provided for convenience of understanding and is not necessary for implementing this solution.

[0053] Example 1

[0054] As Figure 2 shown, this embodiment provides a beam alignment test device for a medical accelerator, including a primary collimator 101, which is arranged in the direction of the ray beam generated at the hitting center. The device further includes:

[0055] The centering collimator 102 is disposed on the side of the primary collimator 101 away from the target center, and the centering collimator 102 is coaxially arranged with the primary collimator 101. A first collimation hole 102a is provided at the center of the centering collimator 102, and second collimation holes 102b are respectively provided on both sides of the first collimation hole 102a. The beam current passes through the initial collimator 101 and the centering collimator 102 in sequence to form a radiation field; and

[0056] The electronic portal imaging device 104 is disposed on the side of the centering collimator 102 away from the primary collimator 101, and is used to image the radiation field to obtain dose intensity distribution data for adjusting the beam centering of the medical accelerator.

[0057] The primary collimator 101, also known as the primary collimation cone, as a part of the medical accelerator, determines the radiation field size of the entire system and the mechanical center of the beam current; the X-ray passes through the primary collimator to form a conical X-ray beam. The centering collimator 102 is made of a metal material capable of shielding rays, such as tungsten. The metal material is provided with beam collimation holes reserved in its structure, and the X-ray generated by the accelerator passes through the centering collimator 102 and forms an image as shown in Figure 3 the figure. Through image data processing, the beam centering deviation direction (deviation angle) and the specific deviation value (deviation distance) can be calculated.

[0058] In a specific example, as shown in Figure 4a and Figure 4b the figure, the centers of the first collimation hole 102a and the second collimation holes 102b of the centering collimator 102 are collinear. Since three collimation holes are provided, the first collimation hole 102a is a circular through hole, and the second collimation holes 102b are square through holes. The X-ray beam forms three parts of the radiation field after passing through the centering collimator, and then forms an image on the electronic portal imaging device 104.

[0059] The medical accelerator beam centering test device of this embodiment generates a center line area and two side areas of the radiation field on the basis of the conical radiation field originally formed by the primary collimator by setting a centering collimator, so as to further calculate the offset distance of the target center in the Inline and Crossline directions through the dose intensity distribution data of the side area radiation fields, and calculate the offset angles of the target center in the Inline (in and out of the bed direction) and Crossline (left and right direction) directions through the dose intensity distribution data of the center line area radiation field. Finally, the target center can be adjusted according to the offset distances and offset angles in each direction to achieve the adjustment of the medical accelerator beam centering.

[0060] In some implementation manners, the medical accelerator beam centering test device of this embodiment further includes:

[0061] The support frame 103 is used to install and support the primary collimator 101 and the alignment collimator 102;

[0062] The bottom surface of the primary collimator 101 is installed on the top of the support frame 103, the alignment collimator 102 is installed inside the support frame 103, and the electronic portal imaging device 104 is installed on the bottom surface of the support frame 103.

[0063] In a specific implementation, the support frame is an integrally processed component, so as to ensure absolute mechanical accuracy, support the alignment collimator and the EPID, and provide an interface for mechanical connection with the accelerator. The EPID is used for imaging the alignment collimator, and the radiation field is imaged on the electronic portal imaging device 104, and then the dose intensity distribution data of the ray can be obtained.

[0064] In some implementation manners, two alignment lines 105 are marked on the top of the support frame 103, and the two alignment lines 105 coincide with the laser lines in the Inline direction of the bed in and out direction and the laser lines in the Crossline direction of the left and right direction respectively. The in-and-out bed direction line 106 on the upper surface of the electronic portal imaging device coincides with the laser line in the in-and-out bed direction, and the left-and-right direction line 107 on the upper surface of the electronic portal imaging device coincides with the laser line in the left-and-right direction, so as to perform beam alignment testing.

[0065] In practical applications, the alignment collimator 102 and the electronic portal imaging device 104 are pre-installed on the support frame 103, and the installation accuracy between the alignment collimator 102 and the support frame 103 is strictly ensured by positioning pins. The support frame 103 is placed at the bottom of the primary collimator 101, and the installation accuracy between the support frame 103 and the primary collimator 101 is strictly ensured by positioning pins. Turn on the laser lights in the Inline and Crossline directions in the shielding machine room, adjust the two laser lights so that the laser lines coincide with the two alignment lines 105 marked on the support frame 103 respectively, and then adjust the electronic portal imaging device 104 so that the in-and-out bed direction line 106 (Inline) and the left-and-right direction line 107 (Crossline) on its surface coincide with the corresponding laser lines respectively.

[0066] Example 2

[0067] This embodiment provides a beam alignment testing method for a medical accelerator, which is implemented based on the beam alignment testing device for a medical accelerator in the above embodiment. The method includes:

[0068] Step 101, a ray beam is generated at the target center.

[0069] Step 102, the ray beam sequentially passes through the initial collimator and the alignment collimator to form a radiation field.

[0070] Step 103: The electronic portal imaging device images the radiation field to obtain dose intensity distribution data for adjusting the beam alignment of the medical accelerator.

[0071] After the beam alignment test device of the medical accelerator in the foregoing embodiment is installed, a beam of rays is generated at the target center. The beam of rays passes through the initial collimator and the alignment collimator in sequence to form a radiation field. The radiation field is imaged on the upper surface of the electronic portal imaging device to obtain dose intensity distribution data of the X-ray. The obtained data is used for adjusting the beam alignment of the medical accelerator.

[0072] Example 3

[0073] This embodiment provides a method for adjusting the beam alignment of a medical accelerator, which can be applied to an electronic device with communication, computing, and data storage capabilities, such as Figure 8 As shown, its process includes:

[0074] Step 201: Collect the dose intensity distribution data obtained by the electronic portal imaging device in the foregoing embodiment.

[0075] Step 202: Respectively extract the dose intensity distribution data sets on the in-out bed direction line and the left-right direction line on the upper surface of the electronic portal imaging device from the dose intensity distribution data.

[0076] Step 203: Based on the dose intensity distribution data sets on the in-out bed direction line and the left-right direction line, calculate the offset distance and offset angle of the target center on the in-out bed direction line and the left-right direction line.

[0077] Step 204: Adjust the target center based on the offset distance and offset angle of the target center on the in-out bed direction line and the left-right direction line.

[0078] In this embodiment, dose intensity distribution datasets on the in-out bed direction line and the left-right direction line on the upper surface of the electronic portal imaging device are respectively extracted from the dose intensity distribution data obtained from the electronic portal imaging device in the previous embodiment. Based on the dose intensity distribution datasets on the in-out bed direction line and the left-right direction line, the offset distances and offset angles of the target hitting centers on the in-out bed direction line and the left-right direction line are calculated, and then the target hitting centers are further adjusted based on the offset distances and offset angles of the target hitting centers on the in-out bed direction line and the left-right direction line. This testing and adjustment method is not affected by the placement position of the electronic portal imaging device, thereby reducing the mechanical positioning accuracy requirements for the electronic portal imaging device. The offset distance and tilt angle values of the electron target hitting center are quantitatively solved from the source, and then corrected by mechanical adjustment. Therefore, only one test and calibration are required after the accelerator product is installed or the beam module is replaced to ensure that the symmetry of the radiation field always meets the requirements in the later stage. The testing and adjustment accuracy only depends on the installation and positioning accuracy of the centering collimator relative to the primary collimator, and this positioning accuracy can be easily guaranteed mechanically. Therefore, the method has high accuracy and is very reliable. At the same time, this method does not introduce additional equipment and software into the product, but only exists in the form of a tooling, reducing the product cost and increasing the reliability of the product. In summary, this method realizes a beam centering test and adjustment method that is both reliable and low-cost.

[0079] In some specific implementations, the dose intensity distribution dataset includes the dose intensity data corresponding to each pixel. Here, it should be understood that the collected dose intensity distribution data is obtained by imaging the radiation field on the electronic portal imaging device, and the extracted dose intensity distribution dataset includes the dose intensity distribution dataset on the in-out bed direction line and the dose intensity distribution dataset on the left-right direction line.

[0080] Furthermore, based on the dose intensity distribution dataset, calculating the offset distance and offset angle of the target hitting center includes:

[0081] Step 203a: Represent the dose intensity distribution dataset as a distribution curve, with the abscissa representing the pixel and the ordinate representing the dose intensity data.

[0082] In this embodiment, since it involves the dose intensity distribution datasets on the in-out bed direction line and the left-right direction line, there are correspondingly distribution curves corresponding to the in-out bed direction line and the left-right direction line for the distribution curve. The first distribution curve is drawn with the dose intensity data corresponding to each pixel on the in-out bed direction line, and the second distribution curve is drawn with the dose intensity data corresponding to each pixel on the left-right direction line.

[0083] The following combines Figure 5 to explain the principle of the beam centering test:

[0084] Figure 5 The left figure in Figure 5 shows the radiation field change on the EPID after the beam hitting center is offset and passes through the centering collimator.

[0085] The solid line corresponding to the hitting center O represents the radiation field boundary on the EPID after the radiation field passes through the centering collimator without offset and tilt of the hitting center. The dashed line corresponding to the hitting center O represents the mechanical center of the beam. The solid line corresponding to the offset hitting center O* represents the radiation field boundary on the EPID after the radiation field passes through the centering collimator with the offset distance OO* of the beam hitting center and the tilt angle θ. The dashed line corresponding to the offset hitting center O* represents the radiation field center. The first distribution curve for showing the radiation field distribution in the Inline direction on the EPID surface is as Figure 6 shown, and the second distribution curve for showing the radiation field distribution in the Crossline direction on the EPID surface is as Figure 7 shown. N represents the pixel width of the radiation field generated by the second collimator hole on the left side of the first collimator hole on the distribution curve, and M represents the pixel width of the radiation field generated by the second collimator hole on the right side of the first collimator hole on the distribution curve.

[0086] Step 203b: Based on the width P of a single pixel, the difference (N - M) in the pixel widths of the radiation fields generated by the second collimator holes on the left and right sides of the first collimator hole, the distance h from the hitting center to the upper surface of the electronic portal imaging device SDD , the distance h from the hitting center to the bottom surface of the centering collimator SID , and the distance h from the hitting center to the bottom surface of the primary collimator SCD , calculate the offset distance OO of the hitting center * .

[0087] Here, the width of a single pixel is determined by the electronic portal imaging device.

[0088] Step 203c: Based on the offset distance of the radiation field center line and the distance c from the hitting center to the upper surface of the electronic portal imaging device, calculate the offset angle θ of the hitting center.

[0089] Taking Figure 6 shown as an example, the horizontal offset distance of the hitting center can be calculated by the following formula

[0090] (b’ - b) - (a - a’) = 2 * [(h SDD - h SCD ) / h SCD - (h SDD - h SID ) / h SID * OO *

[0091] =P*(N - M)

[0092] Wherein, a and a' respectively represent the offsets of the two boundaries of the radiation field formed by the second collimator hole on the left side, and b and b' respectively represent the offsets of the two boundaries of the radiation field formed by the second collimator hole on the right side.

[0093] Therefore

[0094] OO * =P*(N - M) / {2*[(h SDD -h SCD ) / h SCD -(h SDD -h SID ) / h SID}。

[0095] In the formula, OO * represents the offset distance of the target shooting center, h SDD represents the distance from the target shooting center to the upper surface of the electronic portal imaging device, h SID represents the distance from the target shooting center to the bottom surface of the alignment collimator, h SCD represents the distance from the target shooting center to the bottom surface of the primary collimator, P represents the width of a single pixel, N represents the pixel width of the radiation field generated by the second collimator hole on the left side of the first collimator hole on the distribution curve, and M represents the pixel width of the radiation field generated by the second collimator hole on the right side of the first collimator hole on the distribution curve.

[0096] N - M can be calculated through post - processing of the acquired data. In this way, the offset amount (offset distance) and offset direction of the beam target shooting center can be calculated through the distribution of the radiation field (the positive and negative signs of the result represent direction information. If N - M is positive, it means offset to the left; if N - M is negative, it means offset to the right). The calculation accuracy does not depend on the positioning deviation of the EPID, thus reducing the requirement for the mechanical positioning accuracy of the EPID.

[0097] To calculate the offset angle of the target shooting center, the following calculation formula can be used:

[0098] θ = ±arctan(|c / h SDD |)

[0099] In the formula, θ represents the offset angle of the target shooting center, c represents the offset distance of the radiation field center line on the upper surface of the electronic portal imaging device, and h SDD represents the distance from the target shooting center to the upper surface of the electronic portal imaging device.

[0100] In this way, the tilt angle value and tilt direction of the beam target shooting can be calculated through the distribution of the radiation field (the positive and negative signs represent angle direction information. The positive sign indicates offset to the left, and the negative sign indicates offset to the right).

[0101] In some specific implementations, before calculating the offset distance of the shooting center, it further includes:

[0102] (1) Normalize the ordinate values of the distribution curve to obtain a normalized ordinate dataset;

[0103] (2) Expand the abscissa values of the distribution curve to obtain an expanded abscissa dataset, and calculate the corresponding normalized expanded ordinate dataset of the expanded abscissa dataset based on the normalized ordinate dataset, the expanded abscissa dataset, and the original abscissa values of the distribution curve;

[0104] (3) Generate a generated ordinate dataset that satisfies the first normalized ordinate value range with a preset normalized value as the preset interval; determine the first curve segment on the distribution curve corresponding to the radiation field generated by the second collimator on the left side of the first collimator, and the second curve segment on the distribution curve corresponding to the radiation field generated by the second collimator on the right side of the first collimator; based on the generated ordinate dataset, the expanded abscissa dataset, and the normalized expanded ordinate dataset, calculate the corresponding generated abscissa dataset of the generated ordinate dataset for the rising part and the falling part of the first curve segment, and the rising part and the falling part of the second curve segment respectively;

[0105] (4) Calculate the pixel width difference between the first curve segment and the second curve segment based on the generated abscissa dataset to obtain a pixel width difference dataset;

[0106] (5) Calculate the mean value of all pixel width differences corresponding to the second normalized ordinate value range in the pixel width difference dataset, and determine this mean value as the pixel width difference between the radiation fields generated by the second collimators on the left and right sides on the distribution curve; wherein, the second normalized ordinate value range is smaller than the first normalized ordinate value range.

[0107] In some specific implementations, before calculating the offset angle of the shooting center, it further includes:

[0108] Determine the target abscissa value in the expanded abscissa dataset corresponding to 100% in the normalized expanded ordinate dataset;

[0109] Calculate the offset angle of the shooting center based on the coordinates of the center point on the upper surface of the electronic portal imaging device and the target abscissa value.

[0110] The data processing process for calculating the offset distance and offset angle of the shooting center is described below:

[0111] (1) Use the formula y 1 =y / MAX(y)*100 to normalize the ordinate value y of the distribution curve to obtain the normalized ordinate dataset y 1. The ordinate values (dose intensity data) after normalization are percentage data.

[0112] (2) Expand the abscissa values x of the distribution curve by the double equal division method to obtain the abscissa expansion data set x 1 , based on the ordinate normalization data set y 1 , the abscissa expansion data set x 1 and the original abscissa values x of the distribution curve, calculate the ordinate normalization expansion data set y 1 corresponding to the abscissa expansion data set x 2 .

[0113] For example, the original abscissa values are 0, 100, 200,... respectively. After double equal division, the abscissa values are 0, 50, 100, 150, 200,... respectively. Based on the linear regression of the data set, calculate the predicted ordinate normalization expansion data set y 1 of the abscissa expansion data set x 2 = FORECAST(x 1 , y 1 , x).

[0114] (3) The first ordinate normalization value range is from 30% to 80%, which is the region in the dose intensity data set on the distribution curve. Generate a set of ordinate generation data set y from 30% to 80% with an interval of 0.1% 3 . Determine the first curve segment on the distribution curve corresponding to the radiation field generated by the second collimator on the left side of the first collimator, and the second curve segment on the distribution curve corresponding to the radiation field generated by the second collimator on the right side of the first collimator. Based on the linear regression of the data set, for the rising part (the curve corresponding to the left_1 data set) and the falling part (the curve corresponding to the left_2 data set) of the first curve segment, and the rising part (the curve corresponding to the right_1 data set) and the falling part (the curve corresponding to the right_2 data set) of the second curve segment, calculate the predicted abscissa generation data set x 3 of the ordinate generation data set y 2 = FORECAST(y 3 , x 1 , y 2 ). Here, from Figure 6 , 7 it can be seen that in the distribution curves plotted according to the distribution data sets in two directions, there are three peaks in both. The curve segments formed by these three peaks and the adjacent valleys on their respective sides represent the dose intensity data distribution of the corresponding radiation fields. For example, one curve segment on the left represents the dose intensity data distribution of the radiation field located on the left side of the first collimator (from Figure 5The dose intensity data distribution of the radiation field formed by the second collimation hole on the left side (seen from the left side in Figure 5 ), the middle curve segment represents the dose intensity data distribution of the radiation field formed by the first collimation hole in the central region, and the right curve segment represents the dose intensity data distribution of the radiation field formed by the second collimation hole on the right side of the first collimation hole (seen from the

[0115] right side in 3 ). (4) Generate a data set based on the abscissa, calculate the pixel width difference between the first curve segment and the second curve segment, and obtain the pixel width difference data set x 2 = (x 2 _right2 - x 2 _right1) - (x 2 _left2 - x 2 _left1), where x 2 _right1 and x 2 _right2 respectively represent the abscissa generation data sets x 2 of the rising part (the curve corresponding to the right_1 data set) and the falling part (the curve corresponding to the right_2 data set) of the second curve segment calculated in the previous step, and x 2 _left1 and x 2 _left2 respectively represent the rising part (the curve corresponding to the left_1 data set) and the falling part (the curve corresponding to the left_2 data set) of the first curve segment. The pixel width data set of the corresponding curve segment is calculated through the difference between the rising and falling parts of the curve segment, and the difference between the pixel width data sets of the two radiation fields is used to obtain the pixel width difference data set, thereby obtaining the numerical range of N - M.

[0116] (5) Calculate the mean value of all pixel width differences corresponding to the range of 30% - 40% in the pixel width difference data set y 3 , and determine this mean value as the pixel width difference L between the radiation fields generated by the second collimation holes on the left and right sides on the distribution curve = Avg(x 3 _y| 3 30% : y| 3 40% ). Based on the numerical range of N - M (the pixel width difference data set y 3 ) obtained in the previous step, further extract the corresponding pixel width difference data set x 3 according to the numerical range of 30% - 40% corresponding to the longitudinal middle region of the curve segment. The final value of N - M determined by the mean value L of this part of the pixel width difference data can accurately represent the pixel width of the radiation field, and then calculate the accurate offset distance and angle.

[0117] (6) Calculate the horizontal offset OO of the shooting center* = P * L / {2 * [(h SDD - h SCD ) / h SCD - (h SDD - h SID ) / h SID , the direction is determined by OO * positive and negative values.

[0118] (7) Find the x value corresponding to the 100% value in the vertically normalized extended data set y 2 in, assuming this x 1 value is x 1 value is x 1 θ , the pixel coordinates corresponding to the center of the EPID are known to be x 1 CAX , then the angular tilt value (tilt angle) of the target center is θ = arctan(|(x 1 θ - x 1 CAX ) / h SDD |), the direction is determined by the positive and negative values of (x 1 θ - x 1 CAX ).

[0119] Example 4

[0120] This embodiment relates to a beam alignment adjustment device for a medical accelerator. The implementation details of the beam alignment adjustment device for the medical accelerator in this embodiment will be specifically described below. The following content is only the implementation details provided for convenience of understanding and is not necessary for implementing this solution. The schematic diagram of the beam alignment adjustment device for the medical accelerator in this embodiment can be as Figure 9 shown, including a data acquisition module 801, a data extraction module 802, an offset calculation module 803, and an offset adjustment module 804.

[0121] The data acquisition module 801 is used to acquire the dose intensity distribution data obtained by the electronic portal imaging device in the foregoing embodiment.

[0122] The data extraction module 802 is used to respectively extract the dose intensity distribution data sets on the in-out bed direction line and the left-right direction line on the upper surface of the electronic portal imaging device from the dose intensity distribution data.

[0123] The offset calculation module 803 is used to calculate the offset distance and offset angle of the target center on the in-out bed direction line and the left-right direction line based on the dose intensity distribution data sets on the in-out bed direction line and the left-right direction line.

[0124] The offset adjustment module 804 is configured to adjust the targeting center based on the offset distance and offset angle of the targeting center on the in-out bed direction line and the left-right direction line.

[0125] In some specific implementations, the dose intensity distribution dataset includes dose intensity data corresponding to each pixel. It should be understood that the collected dose intensity distribution data is obtained by imaging the radiation field on the electronic portal imaging device, and the extracted dose intensity distribution dataset includes the dose intensity distribution dataset on the in-out bed direction line and the dose intensity distribution dataset on the left-right direction line.

[0126] Further, based on the dose intensity distribution dataset, calculating the offset distance and offset angle of the targeting center includes: representing the dose intensity distribution dataset as a distribution curve, with the abscissa representing pixels and the ordinate representing dose intensity data; based on the width P of a single pixel, the difference (N - M) in the pixel widths of the radiation fields generated by the second collimators on the left and right sides of the first collimator on the distribution curve, the distance h from the targeting center to the upper surface of the electronic portal imaging device SDD 、the distance h from the targeting center to the bottom surface of the centering collimator SID 、the distance h from the targeting center to the bottom surface of the primary collimator SCD , calculating the offset distance OO * ; based on the offset distance of the radiation field center line and the distance c from the targeting center to the upper surface of the electronic portal imaging device, calculating the offset angle θ of the targeting center.

[0127] Taking Figure 6 as an example, the horizontal offset distance of the targeting center can be calculated by the following formula

[0128] OO * =P*(N - M) / {2*[(h SDD -h SCD ) / h SCD -(h SDD -h SID ) / h SID}.

[0129] In the formula, OO * represents the offset distance of the targeting center, h SDD represents the distance from the targeting center to the upper surface of the electronic portal imaging device, h SID represents the distance from the targeting center to the bottom surface of the centering collimator, h SCD represents the distance from the targeting center to the bottom surface of the primary collimator, P represents the width of a single pixel, N represents the pixel width of the radiation field generated by the second collimator on the left side of the first collimator on the distribution curve, and M represents the pixel width of the radiation field generated by the second collimator on the right side of the first collimator on the distribution curve.

[0130] N-M can be calculated through post-processing of the collected data, so that the offset (offset distance) of the beam hitting the target center and the offset direction (the positive or negative sign of the result represents the direction information. If N-M is positive, it means a left offset; if N-M is negative, it means a right offset) can be calculated based on the distribution of the radiation field. The calculation accuracy does not depend on the positioning deviation of the EPID, thus reducing the requirement for the mechanical positioning accuracy of the EPID.

[0131] To calculate the offset angle of the hitting target center, the following calculation formula can be used:

[0132] θ = ±arctan(|c / h SDD |)

[0133] In the formula, θ represents the offset angle of the hitting target center, c represents the offset distance of the center line of the radiation field on the upper surface of the electronic portal imaging device, and h SDD represents the distance from the hitting target center to the upper surface of the electronic portal imaging device.

[0134] In this way, the tilt angle value and tilt direction of the beam hitting the target (the positive or negative sign represents the angle direction information, the positive sign indicates a left offset, and the negative sign indicates a right offset) can be calculated based on the distribution of the radiation field.

[0135] In some specific implementations, before calculating the offset distance of the hitting target center, it further includes:

[0136] (1) Normalize the ordinate values of the distribution curve to obtain a normalized ordinate data set;

[0137] (2) Expand the abscissa values of the distribution curve to obtain an expanded abscissa data set, and calculate the corresponding normalized expanded ordinate data set of the expanded abscissa data set based on the normalized ordinate data set, the expanded abscissa data set, and the original abscissa values of the distribution curve;

[0138] (3) Generate a generated ordinate data set that satisfies the first normalized ordinate value range with a preset normalized value as the preset interval; determine the first curve segment on the distribution curve corresponding to the radiation field generated by the second collimator hole on the left side of the first collimator hole, and the second curve segment on the distribution curve corresponding to the radiation field generated by the second collimator hole on the right side of the first collimator hole; based on the generated ordinate data set, the expanded abscissa data set, and the normalized expanded ordinate data set, calculate the corresponding generated abscissa data set of the generated ordinate data set for the rising and falling parts of the first curve segment and the rising and falling parts of the second curve segment respectively;

[0139] (4) Based on the generated abscissa data set, calculate the pixel width difference between the first curve segment and the second curve segment to obtain a pixel width difference data set;

[0140] (5) Calculate the mean value of all pixel width differences corresponding to the second ordinate normalization value range in the pixel width difference dataset, and determine this mean value as the pixel width difference between the radiation fields generated by the second collimator holes on the left and right sides on the distribution curve; wherein, the second ordinate normalization value range is less than the first ordinate normalization value range.

[0141] In some specific implementations, before calculating the offset angle of the shooting center, it further includes:

[0142] Determine the target abscissa value in the abscissa expansion dataset corresponding to 100% in the ordinate normalization expansion dataset;

[0143] Based on the coordinates of the center point on the upper surface of the electronic portal imaging device and the target abscissa value, calculate the offset angle of the shooting center.

[0144] In this embodiment, it involves the dose intensity distribution dataset on the in-out bed direction line and the dose intensity distribution dataset on the left-right direction line. Therefore, there are also distribution curves corresponding to the in-out bed direction line and the left-right direction line respectively for the distribution curve. The first distribution curve is drawn with the dose intensity data corresponding to each pixel on the in-out bed direction line, and the second distribution curve is drawn with the dose intensity data corresponding to each pixel on the left-right direction line.

[0145] It is worth mentioning that each module involved in this embodiment is a logical module. In practical applications, a logical unit can be a physical unit, a part of a physical unit, or can be implemented by a combination of multiple physical units. In addition, in order to highlight the innovative part of the present invention, units not closely related to solving the technical problems proposed by the present invention are not introduced in this embodiment, but this does not mean that there are no other units in this embodiment.

[0146] Example 5

[0147] This embodiment provides a method for adjusting the beam alignment of a medical accelerator, which is implemented based on a medical accelerator beam alignment test device. The medical accelerator beam alignment test device, as Figure 1 shown, includes:

[0148] The primary collimator 101 is arranged on the ray beam direction generated by the shooting center;

[0149] The centering collimator 102 is arranged on the side of the primary collimator away from the target center. A first collimation hole is provided at the center of the centering collimator. The first collimation hole is coaxially arranged with the primary collimator. A second collimation hole is provided on each side of the first collimation hole. The centers of the first collimation hole and the two second collimation holes are collinear. The beam current sequentially passes through the initial collimator and the centering collimator to form three parts of the radiation field. In one example, the first collimation hole 102a is a circular through hole, and the second collimation hole 102b is a square through hole, such as a rectangle.

[0150] The electronic portal imaging device 104 is arranged on the side of the centering collimator away from the primary collimator, and is used to image the radiation field to obtain dose intensity distribution data for adjusting the beam centering of the medical accelerator. The upper surface of the electronic portal imaging device is provided with an in-out bed direction line 106 and a left-right direction line 107. The in-out bed direction line 106 of the electronic portal imaging device 104 coincides with the laser line in the in-out bed direction, and the left-right direction line 107 on the upper surface of the electronic portal imaging device coincides with the laser line in the left-right direction to perform beam centering test.

[0151] The method for adjusting the beam centering of the medical accelerator includes:

[0152] Step 301, collecting the dose intensity distribution data obtained by the electronic portal imaging device.

[0153] Specifically, the beam current generated at the target center sequentially passes through the initial collimator and the centering collimator to form three parts of the radiation field. The electronic portal imaging device images the radiation field to obtain dose intensity distribution data for adjusting the beam centering of the medical accelerator.

[0154] Step 302, respectively extracting the dose intensities on the in-out bed direction line and the left-right direction line provided on the upper surface of the electronic portal imaging device from the dose intensity distribution data, to obtain a first dose intensity distribution data set on the in-out bed direction line and a second dose intensity distribution data set on the left-right direction line.

[0155] Step 303, based on the first dose intensity distribution data set and the second dose intensity distribution data set, calculating the offset distance and offset angle of the target center on the in-out bed direction line and the left-right direction line.

[0156] In a specific implementation, step 303 further includes:

[0157] Step 303a, representing both the first dose intensity distribution data set and the second dose intensity distribution data set as distribution curves, with the abscissa representing pixels and the ordinate representing dose intensity data, to obtain a first distribution curve and a second distribution curve;

[0158] Step 303b: Based on the width P of a single pixel, the difference in pixel widths (N - M) of the radiation fields generated by the second collimator holes on the left and right sides of the first collimator hole on the distribution curve, and the distance h from the target center to the upper surface of the electronic portal imaging device SDD 、the distance h from the target center to the bottom surface of the centering collimator SID 、the distance h from the target center to the bottom surface of the primary collimator SCD , calculate the offset distance OO of the target center * ;

[0159] The horizontal offset distance of the target center can be calculated by the following formula

[0160] OO * = P * (N - M) / {2 * [(h SDD - h SCD ) / h SCD - (h SDD - h SID ) / h SID}。

[0161] In the formula, OO * represents the offset distance of the target center, h SDD represents the distance from the target center to the upper surface of the electronic portal imaging device, h SID represents the distance from the target center to the bottom surface of the centering collimator, h SCD represents the distance from the target center to the bottom surface of the primary collimator, P represents the width of a single pixel, N represents the pixel width of the radiation field generated by the second collimator hole on the left side of the first collimator hole on the distribution curve, and M represents the pixel width of the radiation field generated by the second collimator hole on the right side of the first collimator hole on the distribution curve.

[0162] Step 303c: Based on the offset distance of the radiation field center line and the distance c from the target center to the upper surface of the electronic portal imaging device, calculate the offset angle θ of the target center.

[0163] To calculate the offset angle of the target center, the following calculation formula can be used:

[0164] θ = ±arctan(|c / h SDD |)

[0165] In the formula, θ represents the offset angle of the target center, c represents the offset distance of the radiation field center line on the upper surface of the electronic portal imaging device, and h SDD represents the distance from the target center to the upper surface of the electronic portal imaging device.

[0166] In this way, the tilt angle value and tilt direction of the beam hitting the target are calculated through the distribution of the radiation field (the positive and negative signs represent the angle direction information, the positive sign indicates a left offset, and the negative sign indicates a right offset).

[0167] Step 304: Adjust the shooting center based on the offset distance and offset angle of the shooting center on the in-out bed direction line and the left-right direction line.

[0168] The method of this embodiment quantitatively solves the offset distance and tilt angle value of the electron shooting center from the source, and then corrects them by mechanical adjustment. Therefore, only one test and calibration are required after the installation of the accelerator product or the replacement of the beam module to ensure that the symmetry of the radiation field always meets the requirements in the later stage. The test and adjustment accuracy only depends on the installation and positioning accuracy of the centering collimator relative to the primary collimator, and this positioning accuracy can be easily guaranteed mechanically. Therefore, the method has high accuracy and reliability. At the same time, this method does not introduce additional equipment and software into the product, but only exists in the form of a tooling, which reduces the product cost and increases the reliability of the product. In summary, this method realizes a beam centering test and adjustment method that is both reliable and low-cost.

[0169] Example 6

[0170] This embodiment provides a method for adjusting the beam centering of a medical accelerator, which is implemented based on a medical accelerator beam centering test device. The medical accelerator beam centering test device, as Figure 1 shown, includes:

[0171] A primary collimator 101, which is arranged on the ray beam direction generated by the shooting center;

[0172] A centering collimator 102, which is arranged on the side of the primary collimator away from the shooting center. A first collimation hole is opened in the center of the centering collimator. The first collimation hole is coaxially arranged with the primary collimator. A second collimation hole is opened on each side of the first collimation hole. The centers of the first collimation hole and the two second collimation holes are collinear. The ray beam passes through the initial collimator and the centering collimator in sequence to form three parts of the radiation field; in an example, the first collimation hole 102a is a circular through hole, and the second collimation hole 102b is a square through hole, such as a rectangle.

[0173] An electronic portal imaging device 104, which is arranged on the side of the centering collimator away from the primary collimator, is used to image the radiation field to obtain dose intensity distribution data for adjusting the beam centering of the medical accelerator. The in-out bed direction line 106 and the left-right direction line 107 are arranged on the upper surface of the electronic portal imaging device. The in-out bed direction line 106 of the electronic portal imaging device 104 coincides with the laser line in the in-out bed direction, and the left-right direction line 107 on the upper surface of the electronic portal imaging device coincides with the laser line in the left-right direction to perform the beam centering test.

[0174] The method for adjusting the beam centering of the medical accelerator includes:

[0175] Step 401: Collect the dose intensity distribution data obtained by the electronic portal imaging device, and separately extract the dose intensity distribution data sets on the in-out couch direction line and the left-right direction line set on the upper surface of the electronic portal imaging device from the dose intensity distribution data.

[0176] Step 402: Normalize the ordinate values of the distribution curve to obtain the normalized ordinate data set.

[0177] Step 403: Expand the abscissa values of the distribution curve to obtain the expanded abscissa data set.

[0178] Step 404: Based on the normalized ordinate data set, the expanded abscissa data set, and the original abscissa values of the distribution curve, calculate the normalized expanded ordinate data set corresponding to the expanded abscissa data set.

[0179] Step 405: Generate a generated ordinate data set that satisfies the first normalized ordinate value range with a preset normalized value as a preset interval.

[0180] Step 406: Determine the first curve segment on the distribution curve corresponding to the radiation field generated by the second collimator on the left side of the first collimator, and the second curve segment on the distribution curve corresponding to the radiation field generated by the second collimator on the right side of the first collimator; based on the generated ordinate data set, the expanded abscissa data set, and the normalized expanded ordinate data set, calculate the generated abscissa data set corresponding to the generated ordinate data set for the rising part and the falling part of the first curve segment, and the rising part and the falling part of the second curve segment respectively.

[0181] Step 407: Based on the generated abscissa data set, calculate the pixel width difference between the first curve segment and the second curve segment to obtain the pixel width difference data set; calculate the mean value of all pixel width differences corresponding to the second normalized ordinate value range in the pixel width difference data set, and determine the mean value as the pixel width difference between the radiation fields generated by the second collimators on the left and right sides on the distribution curve; where the second normalized ordinate value range is smaller than the first normalized ordinate value range.

[0182] Step 408: Determine the target abscissa value in the expanded abscissa data set corresponding to 100% in the normalized expanded ordinate data set, and calculate the offset angle of the aiming center based on the coordinates of the center point on the upper surface of the electronic portal imaging device and the target abscissa value.

[0183] Step 409: Adjust the aiming center based on the offset distance and offset angle of the aiming center on the in-out couch direction line and the left-right direction line.

[0184] The following uses a specific example to illustrate the calculation process of the offset distance and offset angle of the aiming center:

[0185] (1) Using the formula y 1 = y / MAX(y) * 100, the ordinate values y of the distribution curve are normalized to obtain the ordinate normalization data set y 1 . The normalized ordinate values (dose intensity data) are percentage data.

[0186] (2) The abscissa values x of the distribution curve are expanded by double equal division to obtain the abscissa expansion data set x 1 . Based on the ordinate normalization data set y 1 , the abscissa expansion data set x 1 and the original abscissa values x of the distribution curve, calculate the ordinate normalization expansion data set y 1 corresponding to the abscissa expansion data set x 2 .

[0187] For example, the original abscissa values are 0, 100, 200, ……, after double equal division, the abscissa values are 0, 50, 100, 150, 200……. Based on the linear regression of the data set, calculate the predicted ordinate normalization expansion data set y 1 of the abscissa expansion data set x 2 = FORECAST(x 1 , y 1 , x).

[0188] (3) The first ordinate normalization value range is from 30% to 80%, which is the region in the dose intensity data set on the distribution curve. Generate a set of ordinate generation data set y 3 from 30% to 80% with an interval of 0.1%. Determine the first curve segment on the distribution curve corresponding to the radiation field generated by the second collimator on the left side of the first collimator, and the second curve segment on the distribution curve corresponding to the radiation field generated by the second collimator on the right side of the first collimator. Based on the linear regression of the data set, for the rising part (the curve corresponding to the left_1 data set) and the falling part (the curve corresponding to the left_2 data set) of the first curve segment, and the rising part (the curve corresponding to the right_1 data set) and the falling part (the curve corresponding to the right_2 data set) of the second curve segment, calculate the predicted abscissa generation data set x 3 of the ordinate generation data set y 2 = FORECAST(y 3 , x 1 , y 2 ). Here, from Figure 6 , 7It can be seen that the distribution curves drawn based on the distribution data sets in the two directions contain three peaks. The curve segments formed by these three peaks and the troughs adjacent to each other on both sides represent the dose intensity data distribution of the corresponding radiation field. For example, the curve segment on the left represents the left side of the first collimation hole (from Figure 5 shows the dose intensity data distribution of the radiation field formed by the second collimator hole (from the left side), the middle curve segment shows the dose intensity data distribution of the radiation field formed by the first collimator hole in the central area, and the right curve segment shows the dose intensity data distribution of the radiation field formed by the second collimator hole (from the left side) in the central area. Figure 5 The dose intensity data distribution of the radiation field formed by the second collimation hole on the right side of the image.

[0189] (4) Generate a data set based on the horizontal coordinate, calculate the pixel width difference between the first curve segment and the second curve segment, and obtain the pixel width difference data set x 3 =(x 2 _Right 2—x 2 _right 1)—(x 2 _Left 2—x 2 _Left 1), where x 2 _Right 1, x 2 _Right 2 represents the horizontal coordinate of the rising part of the second curve segment calculated in the previous step (the curve corresponding to the right_1 data set) to generate the data set x 2 and the horizontal coordinate of the descending part (the curve corresponding to the right_2 data set) generates the data set x 2 ,x 2 _Left 1, x 2 _Left 2 represents the rising part (curve corresponding to the left_1 data set) and the falling part (curve corresponding to the left_2 data set) of the first curve segment. The pixel width data set of the corresponding curve segment is obtained by calculating the difference between the rising and falling parts of the curve segment. The difference between the pixel width data sets of the two radiation fields is used to obtain the pixel width difference data set, thereby obtaining the numerical range of NM.

[0190] (5) Calculate the pixel width difference data set y 3 The average of all pixel width differences corresponding to the range of 30%~40% is determined as the pixel width difference of the radiation field generated by the second collimation holes on the left and right sides on the distribution curve L=Avg(x 3 _ y| 3 30% : y| 3 40% ). In the previous step, we get the value range of NM (pixel width difference dataset y 3 ) is further extracted according to the value range of 30%~40% corresponding to the middle area of ​​the curve segment, and the corresponding pixel width difference data set x is extracted.​​​3 The final value of N - M determined by the mean value L of this part of the pixel width difference data can accurately represent the pixel width of the radiation field, and then the accurate offset distance and angle can be calculated.

[0191] (6) Calculate the horizontal offset OO of the shooting center * = P * L / {2 * [(h SDD - h SCD ) / h SCD - (h SDD - h SID ) / h SID , and the direction is determined by the positive and negative values of OO * .

[0192] (7) Find the x value corresponding to the 100% value in the normalized extended data set y of the ordinate. Assume that this x value is x 2 1 1 1 θ , and the pixel coordinates corresponding to the EPID center are known as x 1 CAX . Then the angle tilt value (tilt angle) of the shooting center is θ = arctan(|(x 1 θ - x 1 CAX ) / h SDD |), and the direction is determined by the positive and negative values of (x 1 θ - x 1 CAX ).

[0193] The method of this embodiment quantitatively solves the offset distance and tilt angle values of the electron shooting center from the source, and then corrects them by mechanical adjustment. Only one test and calibration are required after the installation of the accelerator product or the replacement of the beam module to ensure that the symmetry of the radiation field always meets the requirements in the later stage. The test and adjustment accuracy only depends on the installation and positioning accuracy of the centering collimator relative to the primary collimator, and this positioning accuracy can be easily ensured mechanically. Therefore, the method has high accuracy and reliability. At the same time, this method does not introduce additional equipment and software into the product, but only exists in the form of a tooling, which reduces the product cost and increases the reliability of the product. In summary, this method realizes a beam centering test and adjustment method that is both reliable and low - cost.

[0194] Example 7

[0195] This embodiment provides an electronic device, including:

[0196] At least one processor; and, ​​​

[0197] A memory communicatively connected to at least one processor; wherein,

[0198] The memory stores instructions executable by at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the above-mentioned method for adjusting the beam alignment of a medical accelerator.

[0199] Wherein, the memory and the processor are connected by a bus, and the bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors and the memory together. The bus may also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, etc., which are well known in the art, and therefore, will not be further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver may be one element or multiple elements, such as multiple receivers and transmitters, and provides a unit for communicating with various other devices on the transmission medium. The data processed by the processor is transmitted on the wireless medium through the antenna. Further, the antenna also receives data and transmits the data to the processor.

[0200] The processor is responsible for managing the bus and general processing, and may also provide various functions, including timing, peripheral interface, voltage regulation, power management, and other control functions. And the memory may be used to store data used by the processor when executing operations.

[0201] Example 8

[0202] This embodiment provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the above-mentioned method for adjusting the beam alignment of a medical accelerator is implemented.

[0203] Those skilled in the art can understand that all or part of the steps in implementing the methods of the above embodiments can be completed by instructing relevant hardware through a program, and the program is stored in a storage medium, including several instructions for enabling a device (which may be a single-chip microcomputer, a chip, etc.) or a processor to execute all or part of the steps of the methods described in various embodiments of the present invention. And the foregoing storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROM for short), random access memories (RAM for short), magnetic disks, or optical discs, etc., which can store program codes.

[0204] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes can be made in form and details without departing from the spirit and scope of the present invention.

Claims

1. A medical accelerator beam centering test device, comprising a primary collimator, arranged in the direction of the ray beam generated by the target center, characterized in that: The device also includes: A centering collimator is arranged on a side of the primary collimator away from the target center, and the centering collimator is coaxially arranged with the primary collimator. A first collimation hole is opened at the center of the centering collimator, and second collimation holes are opened on both sides of the first collimation hole. The ray beam passes through the primary collimator and the centering collimator in sequence to form a radiation field. The electronic portal imaging device is arranged on the side of the centering collimator away from the primary collimator, and is used to image the radiation field to obtain dose intensity distribution data for centering adjustment of the medical accelerator beam.

2. The medical accelerator beam centering test device according to claim 1, characterized in that: Also includes: A support frame, used for mounting and supporting the primary collimator and the centering collimator; The bottom surface of the primary collimator is installed on the top of the support frame, the centering collimator is installed inside the support frame, and the electronic portal imaging device is installed on the bottom surface of the support frame.

3. The medical accelerator beam centering test device according to claim 2, characterized in that: Two centering lines are marked on the top of the support frame, and the two centering lines coincide with the laser lines in the direction of entering and exiting the bed and the laser lines in the left and right directions respectively. The line in the direction of entering and exiting the bed on the upper surface of the electronic portal imaging device coincides with the laser lines in the direction of entering and exiting the bed, and the left and right direction lines on the upper surface of the electronic portal imaging device coincide with the laser lines in the left and right directions, so as to perform a beam centering test.

4. A medical accelerator beam alignment test method, characterized in that: A medical accelerator beam centering test device is implemented based on any one of claims 1 to 3; the method comprises: A beam of radiation is generated at the target center; The ray beam sequentially passes through the primary collimator and the centering collimator to form a radiation field; The electronic portal imaging device images the radiation field to obtain dose intensity distribution data for centering and adjusting the medical accelerator beam.

5. A method for adjusting the centering of a medical accelerator beam, characterized in that: include: Collecting dose intensity distribution data obtained by the electronic portal imaging device of claim 4; Extracting the dose intensity on the bed entry and exit direction line and the left and right direction line of the upper surface of the electronic portal imaging device from the dose intensity distribution data; Based on the dose intensity distribution data set on the bed in and out direction line and the left and right direction line, the offset distance and offset angle of the target center on the bed in and out direction line and the left and right direction line are calculated; Adjust the target center based on the offset distance and offset angle of the target center on the bed entry and exit direction line and the left and right direction line.

6. The medical accelerator beam centering adjustment method according to claim 5, characterized in that: The dose intensity distribution data set includes dose intensity data corresponding to each pixel; Based on the dose intensity distribution data set, calculating the offset distance and offset angle of the target center includes: The dose intensity distribution data set is represented by a distribution curve, where the abscissa represents pixels and the ordinate represents dose intensity data; Calculate the offset distance of the target center based on the width of a single pixel, the difference in pixel widths of the radiation fields generated by the second collimating holes on the left and right sides of the first collimating hole on the distribution curve, the distance from the target center to the upper surface of the electronic portal imaging device, the distance from the target center to the bottom surface of the centering collimator, and the distance from the target center to the bottom surface of the primary collimator; The offset angle of the target center is calculated based on the offset distance of the radiation field center line and the distance from the target center to the upper surface of the electronic portal imaging device.

7. The medical accelerator beam centering adjustment method according to claim 6, characterized in that: Calculate the offset distance of the target center using the following formula: OO * =P*(N-M) / {2*[(h SDD -h SCD ) / h SCD -(h SDD -h SID ) / h SID ]} In the formula, OO * Indicates the offset distance of the target center, h SDD It represents the distance from the center of the target to the upper surface of the electronic portal imaging device, h SID Indicates the distance from the target center to the bottom of the centering collimator, h SCD It represents the distance from the target center to the bottom surface of the primary collimator, P represents the width of a single pixel, N represents the pixel width of the radiation field generated by the second collimator hole on the left side of the first collimator hole on the distribution curve, and M represents the pixel width of the radiation field generated by the second collimator hole on the right side of the first collimator hole on the distribution curve.

8. The medical accelerator beam centering adjustment method according to claim 6, characterized in that: Calculate the offset angle of the target center using the following formula: θ=±arctan(|c / h SDD |) In the formula, θ represents the offset angle of the target center, c represents the offset distance of the radiation field centerline on the upper surface of the electronic portal imaging device, and h SDD Indicates the distance from the center of the target to the upper surface of the electronic portal imaging device.

9. An electronic device, characterized in that: include: at least one processor; as well as, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the medical accelerator beam centering adjustment method according to any one of claims 5 to 8.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the medical accelerator beam centering adjustment method according to any one of claims 5 to 8 is implemented.

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