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

Abstract

The embodiment of the invention relates to the field of medical accelerators, and provides a medical accelerator beam centering test device, test method and adjustment method, the device comprises a centering collimator, the center of the centering collimator is provided with a first collimating hole, the two sides of the first collimating hole are respectively provided with a second collimating hole, a ray beam sequentially passes through the initial collimator and the centering collimator to form a radiation field; and the electron radiation field imaging device is arranged on one side, far away from the primary collimator, of the centering collimator and is used for imaging a radiation field to obtain dose intensity distribution data. Respectively extracting dose intensity distribution data sets on a bed entering and exiting direction line and a left-right direction line from the dose intensity distribution data, and calculating offset distances and offset angles of targeting centers on the bed entering and exiting direction line and the left-right direction line; and adjusting the targeting center based on the offset distance and the offset angle of the targeting center on the bed entering and exiting direction line and the left-right direction line. According to the invention, the centering test and adjustment precision is high and reliable, and the product cost is reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of medical accelerators, and in particular to a medical accelerator beam centering test device, test method and adjustment method. Background Art

[0002] The symmetry of the radiation field should not exceed 103%, which is one of the important performance indicators of medical accelerators. This is clearly required in the medical accelerator standard "Medical Accelerator-Performance and Test Methods" GB 15213-2016 5.3.1.3. In order to meet the symmetry requirements, it is necessary to calibrate the accelerator beam so that the target center coincides with the mechanical center of the treatment head. This calibration step must be performed during the initial assembly stage of the accelerator beam module in the factory and after the accelerator beam module is replaced on-site in the hospital. At present, the calibration process of each manufacturer is confidential information. Among some related technologies that can be known to technical personnel in this field, an ionization chamber is used to measure the symmetry deviation, and then the direction of the beam target is controlled by a guide coil. Although this method can achieve rapid beam centering adjustment, it will also bring the following problems: a) The above method is not applicable to accelerators without guide coils. The current mainstream accelerators are low-energy machines (single energy ≤ 6 MV), which can cover about 85% of the market. The accelerating tubes used in low-energy machines are short, generally no longer than 40 cm, and have no guide coil system.

[0003] b) The medical accelerator itself is a very complex system. If a beam alignment control system is introduced, the complexity of the system will be further increased, while the cost and the risk of system failure will also be increased. Summary of the invention

[0004] The purpose of the present invention is to at least provide a medical accelerator beam centering test device, test method and adjustment method, which can at least solve the problem that the traditional beam centering adjustment method is not applicable to accelerators without guide coils. There is no need to introduce a beam centering control system to increase the complexity and cost of the system, and the risk of system failure can be reduced.

[0005] In order to solve the above technical problems, at least one embodiment of the present invention provides a medical accelerator beam centering test device, comprising a primary collimator arranged in the direction of the ray beam generated by the target center, and the device further comprises: 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 initial 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.

[0006] In some optional embodiments, the medical accelerator beam centering test device further 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.

[0007] In some optional 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 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 alignment test.

[0008] At least one embodiment of the present invention further provides a medical accelerator beam centering test method, which is implemented based on the above-mentioned medical accelerator beam centering test device; the method comprises: A beam of radiation is generated at the target center; The ray beam passes through the initial collimator and the centering collimator in sequence 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.

[0009] At least one embodiment of the present invention further provides a method for adjusting the centering of a medical accelerator beam, comprising: Collecting dose intensity distribution data obtained by electronic portal imaging device; Extracting dose intensity distribution data sets on the bed entry and exit direction lines and the left and right direction lines on 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.

[0010] In some optional embodiments, the dose intensity distribution data set includes dose intensity data corresponding to each pixel; and 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.

[0011] In some optional embodiments, the offset distance of the target center is calculated using the following calculation formula: OO * =P*(NM) / {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.

[0012] In some optional embodiments, the offset angle of the target center is calculated using the following calculation 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.

[0013] At least one embodiment of the present invention further provides an electronic device, including: at least one processor; and, 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 so that the at least one processor can execute the above-mentioned medical accelerator beam centering adjustment method.

[0014] At least one embodiment of the present invention further provides a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the above-mentioned medical accelerator beam centering adjustment method.

[0015] The present invention sets a pair of centering collimators to generate three radiation fields, namely the centerline area and the left and right side areas, on the basis of the conical radiation field originally formed by the primary 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 radiation fields in the left and right side areas, and calculate the offset angle of the target center in the Inline and Crossline directions through the dose intensity distribution data of the radiation field in the centerline area. Finally, the target center can be adjusted according to the offset distance and offset angle in each direction, so as to realize the centering adjustment of the medical accelerator beam. The test and adjustment accuracy only depends on the installation positioning accuracy of the centering collimator relative to the primary collimator. The centering test and adjustment are highly accurate and reliable, without the need to introduce additional equipment and software, thus reducing product costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily described by the pictures in the corresponding drawings, and these exemplary descriptions do not constitute limitations on the embodiments.

[0017] Figure 1 It is a schematic diagram of the principle of beam centering deviation; Figure 2 It is a schematic structural diagram of a medical accelerator beam centering test device provided by an embodiment of the present invention; Figure 3 is a schematic diagram of imaging on an EPID provided by an embodiment of the present invention; Figure 4a and Figure 4b is a schematic diagram of a centering collimator shown at different angles provided by an embodiment of the present invention; Figure 5 is a schematic diagram of the beam centering test principle provided by an embodiment of the present invention; Figure 6 is a schematic diagram of a first distribution curve provided by an embodiment of the present invention; Figure 7 is a schematic diagram of a second distribution curve provided by an embodiment of the present invention; Figure 8 It is a schematic flow chart of a medical accelerator beam centering adjustment method provided by an embodiment of the present invention; Fig. 9 It is a schematic diagram of a medical accelerator beam centering adjustment device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. However, it can be understood by those skilled in the art that in the embodiments of the present invention, many technical details are proposed in order to enable the reader to better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present invention can also be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0019] In order to facilitate understanding of the embodiments of the present invention, relevant contents about beam centering deviation are first introduced here.

[0020] The following figure further explains the principle of beam misalignment: like Figure 1 As shown, the dot represents the accelerator beam targeting center, the gray block represents the primary collimator (conical structure, X-rays pass through the primary collimator to form a cone beam), the mechanical center of the primary collimator is the mechanical center of the entire accelerator system, and the yellow part represents the Electronic Portal Imaging Device (EPID). The rays generated by the beam targeting pass through the primary collimator and form a radiation field of a certain shape on the EPID. In theory, the installation of the accelerator requires that the beam targeting center and the mechanical center of the primary collimator coincide, so that the symmetry of the radiation field will meet regulatory requirements. However, as an extremely large system, the accelerator weighs several tons as a whole, and it is difficult to ensure center coincidence during the installation process. In addition, there are deviations in the welding of the accelerator's own target point, which requires beam centering calibration after the accelerator is installed. When the targeting center is offset from the primary collimator by a distance of OO * When the radiation field boundary collected on the EPID is offset by a distance of AA * , A.A. * / OO * =(h SDD -h SCD ) / h SCD . Conventional medical accelerator (h SDD -h SCD ) / h SCD ≈10, the radiation field offset will be magnified by nearly 10 times, such as OO * When the deviation is 0.1 mm, AA *The deviation is close to 1mm. The deviation of the radiation field boundary reflects the deviation of the target center. When the target center is tilted by θ, the radiation field center deviates CC. * , where θ=±arctan(|CC * / h SDD |), the shift in the center of the radiation field reflects the angular tilt of the target center.

[0021] In order to solve the above-mentioned technical problem of beam centering calibration, the present invention proposes a medical accelerator beam centering test device, test method and adjustment method. The implementation details of the medical accelerator beam centering test device, test method and adjustment method provided by the present invention are specifically described below. The following content is only for the convenience of understanding the implementation details provided, and is not necessary for the implementation of this solution.

[0022] Embodiment 1 like Figure 2 As shown, this embodiment provides a medical accelerator beam centering test device, including a primary collimator 101, which is arranged in the direction of the ray beam generated by the target center, and the device also includes: A centering collimator 102 is arranged on a 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 opened at the center of the centering collimator 102, and second collimation holes 102b are opened on both sides of the first collimation hole 102a. The ray beam passes through the initial collimator 101 and the centering collimator 102 in sequence to form a radiation field; and 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 and obtain dose intensity distribution data for centering adjustment of the medical accelerator beam.

[0023] The primary collimator 101 is also called the primary collimator cone. As a part of the medical accelerator, it determines the radiation field size of the entire system and the mechanical center of the beam. X-rays pass through the primary collimator to form a cone-shaped X-ray beam. The centering collimator 102 is made of a metal material that can shield radiation, such as tungsten. The metal material structure has a reserved beam collimation hole. The X-rays generated by the accelerator pass through the centering collimator 102 and form a beam on the EPID. Figure 3 The image shown. Through image data processing, the direction of beam centering deviation (deviation angle) and the specific deviation value (deviation distance) can be calculated.

[0024] In a specific example, Figure 4a and Figure 4bAs shown, the centers of the first collimation hole 102a and the second collimation hole 102b of the centering collimator 102 are collinear. Since it has three collimation holes, the first collimation hole 102a is a circular through hole, and the second collimation hole 102b is a square through hole, the X-ray beam forms three radiation fields after passing through the centering collimator, and then forms an image on the electronic portal imaging device 104. The medical accelerator beam centering test device of this embodiment, by setting a pair of centering collimators, generates three radiation fields of a centerline area and left and right side areas on the basis of the conical radiation field originally formed by the primary 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 radiation fields in the left and right side areas, and calculate the offset angle of the target center in the Inline (in and out of the bed direction) and Crossline (left and right directions) directions through the dose intensity distribution data of the radiation field in the centerline area. Finally, the target center can be adjusted according to the offset distance and offset angle in each direction, so as to realize the medical accelerator beam centering adjustment.

[0025] In some implementations, the medical accelerator beam centering test device of this embodiment further includes: A support frame 103, used for mounting and supporting the primary collimator 101 and the centering collimator 102; The bottom surface of the primary collimator 101 is mounted on the top of the support frame 103 , the centering collimator 102 is mounted inside the support frame 103 , and the electronic portal imaging device 104 is mounted on the bottom surface of the support frame 103 .

[0026] In a specific implementation, the support frame is an integrated processing component to ensure absolute mechanical precision, and is used to support the centering collimator and EPID, and provide an interface for mechanical connection with the accelerator. The EPID is used to image the centering collimator, and the radiation field is imaged on the electronic portal imaging device 104, thereby obtaining the dose intensity distribution data of the radiation.

[0027] In some implementations, two centering lines 105 are marked on the top of the support frame 103, and the two centering lines 105 coincide with the laser line Inline in the bed direction and the laser line Crossline in the left and right directions, respectively. The bed in-and-out direction line 106 on the upper surface of the electronic portal imaging device coincides with the laser line in the 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 directions, so as to perform a beam centering test.

[0028] In actual application, the centering collimator 102 and the electronic portal imaging device 104 are pre-installed on the support frame 103, and the installation accuracy between the centering collimator 102 and the support frame 103 is strictly guaranteed by the 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 guaranteed by the positioning pins. Turn on the laser lights in the Inline and Crossline directions in the shielding room, adjust the two laser lights so that the laser lines coincide with the two centering lines 105 marked on the support frame 103, and then adjust the electronic portal imaging device 104 so that the bed in and out direction line 106 (Inline) and the left and right direction line 107 (Crossline) on its surface coincide with the corresponding laser lines.

[0029] Embodiment 2 This embodiment provides a medical accelerator beam centering test method, which is implemented based on the medical accelerator beam centering test device of the above embodiment. The method includes: Step 101: Generate a ray beam at the target center.

[0030] Step 102: The ray beam passes through the initial collimator and the centering collimator in sequence to form a radiation field.

[0031] Step 103: The electronic portal imaging device images the radiation field to obtain dose intensity distribution data for centering adjustment of the medical accelerator beam.

[0032] After the medical accelerator beam centering test device of the aforementioned embodiment is installed, a ray beam is generated at the target center, and the ray beam passes through the initial collimator and the centering collimator in sequence to form a radiation field. The radiation field is imaged on the upper surface of the electronic field imaging device to obtain X-ray dose intensity distribution data, and the obtained data is used to adjust the medical accelerator beam centering.

[0033] Embodiment 3 This embodiment provides a method for adjusting the centering of a medical accelerator beam, which can be applied to electronic devices with communication, computing and data storage capabilities, such as Figure 8 As shown, the process includes: Step 201 : collecting the dose intensity distribution data obtained by the electronic portal imaging device in the above-mentioned embodiment.

[0034] Step 202: extracting dose intensity distribution data sets on the bed entry and exit direction lines and the left and right direction lines on the upper surface of the electronic portal imaging device from the dose intensity distribution data.

[0035] Step 203: Calculate 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 based on the dose intensity distribution data set on the bed entry and exit direction line and the left and right direction line.

[0036] Step 204: 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.

[0037] In this embodiment, the dose intensity distribution data sets on the bed entry and exit direction lines and the left and right direction lines on the upper surface of the electronic portal imaging device are respectively extracted from the dose intensity distribution data obtained by the electronic portal imaging device in the aforementioned embodiment. Based on the dose intensity distribution data sets on the bed entry and exit direction lines and the left and right direction lines, the offset distance and offset angle of the target center on the bed entry and exit direction lines and the left and right direction lines are calculated, and then the target center is further adjusted based on the offset distance and offset angle of the target center on the bed entry and exit direction lines and the left and right direction lines. This test 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 electronic target center are quantitatively solved from the source, and then corrected by mechanical adjustment. Therefore, only one test and calibration is required after the accelerator product is installed or the beam module is replaced to ensure that the symmetry of the later radiation field always meets the requirements. The test and adjustment accuracy only depends on the installation positioning accuracy of the centering collimator relative to the primary collimator. The positioning accuracy is easy to ensure mechanically, so the method is very accurate and reliable. At the same time, this method does not introduce additional equipment and software into the product, but only exists in the form of tooling, which reduces product cost and increases product reliability. In summary, this method realizes a reliable and low-cost beam alignment test and adjustment method.

[0038] In some specific implementations, the dose intensity distribution data set includes 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 an electronic portal imaging device, and the extracted dose intensity distribution data set includes a dose intensity distribution data set on a bed in and out direction line and a dose intensity distribution data set on a left and right direction line.

[0039] Furthermore, based on the dose intensity distribution data set, the offset distance and offset angle of the target center are calculated, including: Step 203a: Represent the dose intensity distribution data set with a distribution curve, where the horizontal axis represents pixels and the vertical axis represents dose intensity data.

[0040] In this embodiment, a dose intensity distribution data set on the bed entry and exit direction line and a dose intensity distribution data set on the left and right direction line are involved. Therefore, there are corresponding distribution curves corresponding to the bed entry and exit direction line and the left and right direction line respectively. The first distribution curve is drawn using the dose intensity data corresponding to each pixel on the bed entry and exit direction line, and the second distribution curve is drawn using the dose intensity data corresponding to each pixel on the left and right direction line.

[0041] Combine the following Figure 5 Explain the principle of beam centering test: Figure 5 The left figure shows the change of radiation field on EPID after the beam target center is offset and passed through the centering collimator. Figure 5 The right figure shows the change of radiation field on EPID after the beam target center is tilted and passed through the centering collimator cone.

[0042] The solid line corresponding to the target center O represents the radiation field boundary on the EPID after the radiation field passes through the centering collimator when the target center is not offset and tilted. The dotted line corresponding to the target center O represents the mechanical center of the beam. The solid line corresponding to the offset target center O* represents the radiation field boundary on the EPID after the beam target center is offset by a distance OO* and a tilt angle θ. The dotted line corresponding to the offset target center O* represents the radiation field center. The first distribution curve used to show the radiation field distribution in the Inline direction of the EPID surface is as follows: Figure 6 As shown in FIG. 1 , the second distribution curve used to show the radiation field distribution in the crossline direction of the EPID surface is as follows: Figure 7 As shown, N represents the pixel width of the radiation field generated by the second collimating hole on the left side of the first collimating hole on the distribution curve, and M represents the pixel width of the radiation field generated by the second collimating hole on the right side of the first collimating hole on the distribution curve.

[0043] Step 203b, based on the width P of a single pixel, the difference in pixel width (NM) between the radiation fields generated by the second collimating holes on the left and right sides of the first collimating hole, and the distance h from the center of the target to the upper surface of the electronic portal imaging device, SDD , the distance from the target center to the bottom surface of the centering collimator h SID , the distance from the target center to the bottom of the primary collimator h SCD , calculate the offset distance OO of the target center * .

[0044] Here, the width of a single pixel is determined by the electronic portal imaging device.

[0045] Step 203c: Calculate the offset angle θ of the target center 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.

[0046] by Figure 6 Taking the example shown in the figure, the horizontal offset distance of the target center can be calculated by the following formula (b'-b)-(a-a')=2*[(h SDD -h SCD ) / h SCD -(h SDD -h SID ) / h SID ]*OO * =P*(NM) Wherein, a and a' respectively represent the offsets of the two boundaries of the radiation field formed by the second collimating hole on the left, and b and b' respectively represent the offsets of the two boundaries of the radiation field formed by the second collimating hole on the right.

[0047] so OO * =P*(NM) / {2*[(h SDD -h SCD ) / h SCD -(h SDD -h SID ) / h SID ]}.

[0048] 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.

[0049] NM can be calculated through post-processing of the collected data, so that the offset (offset distance) and offset direction of the beam target center can be calculated through the distribution of the radiation field (the positive and negative signs of the results represent the direction information, if NM is positive, it will be offset to the left, and if NM is negative, it will be offset to the right). The calculation accuracy does not depend on the positioning deviation of the EPID, thus reducing the mechanical positioning accuracy requirements for the EPID.

[0050] To calculate the offset angle of the target center, the following formula can be used: 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 hSDD Indicates the distance from the center of the target to the upper surface of the electronic portal imaging device.

[0051] In this way, the tilt angle value and tilt direction of the beam targeting are calculated through the distribution of the radiation field (the positive and negative signs represent the angle direction information, the positive sign indicates a leftward shift, and the negative sign indicates a rightward shift).

[0052] In some specific implementations, before calculating the offset distance of the target center, the method further includes: (1) Normalize the ordinate value of the distribution curve to obtain a ordinate normalized data set; (2) Expanding the abscissa values ​​of the distribution curve to obtain an abscissa expanded data set, and calculating a ordinate normalized expanded data set corresponding to the abscissa expanded data set based on the ordinate normalized data set, the abscissa expanded data set, and the original abscissa values ​​of the distribution curve; (3) Generate a vertical coordinate generation data set with a preset normalized value as a preset interval that satisfies the normalized value range of the first vertical coordinate; determine a 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 a 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 vertical coordinate generation data set, the horizontal coordinate expansion data set and the vertical coordinate normalized expansion data set, respectively 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, calculate the horizontal coordinate generation data set corresponding to the vertical coordinate generation data set; (4) generating a data set based on the horizontal coordinate, calculating the pixel width difference between the first curve segment and the second curve segment, and obtaining a pixel width difference data set; (5) Calculate the mean of all pixel width differences corresponding to the normalized value range of the second ordinate in the pixel width difference data set, and determine the mean as the difference in pixel widths of the radiation fields generated by the second collimating holes on the left and right sides on the distribution curve; wherein the normalized value range of the second ordinate is smaller than the normalized value range of the first ordinate.

[0053] In some specific implementations, before calculating the offset angle of the target center, the method further includes: Determine the target abscissa value in the abscissa expanded data set corresponding to 100% in the ordinate normalized expanded data set; Based on the coordinates of the center point on the upper surface of the electronic portal imaging device and the target horizontal coordinate value, the offset angle of the target center is calculated.

[0054] The following is an explanation of the data processing process for calculating the offset distance and offset angle of the target center: (1) Using the formula y 1=y / MAX(y)*100, normalize the ordinate value y of the distribution curve to obtain the ordinate normalized data set y 1 The normalized vertical axis values ​​(dose intensity data) are percentage data.

[0055] (2) Expand the horizontal coordinate value x of the distribution curve by doubling it to obtain the horizontal coordinate expanded data set x 1 , based on the normalized dataset y 1 , the horizontal axis expands the data set x 1 and the original horizontal coordinate value x of the distribution curve, calculate the horizontal coordinate expansion data set x 1 The corresponding ordinate normalized expanded data set y 2 .

[0056] For example, the original horizontal axis values ​​are 0, 100, 200, ..., and after doubling, the horizontal axis values ​​are 0, 50, 100, 150, 200, ... Based on the linear regression of the data set, calculate the horizontal axis expansion data set x 1 The budget of the vertical coordinate normalized expansion data set y 2 =FORECAST(x 1 ,y 1 ,x).

[0057] (3) The normalized value range of the first vertical axis is 30% to 80%, which is the area in the dose intensity data set on the distribution curve. A set of vertical axes with intervals of 0.1% from 30% to 80% is generated to generate the data set y 3 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 linear regression of the data set, calculate the ordinate to generate the data set y for 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, and the rising part (curve corresponding to the right_1 data set) and the falling part (curve corresponding to the right_2 data set) of the second curve segment. 3 The horizontal axis of the budget generates the data set x 2 =FORECAST(y 3 ,x 1 ,y 2 ). Here, from Figure 6 , 7 It 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 dose intensity data distribution on the left side of the first collimator hole (from Figure 5The dose intensity data distribution of the radiation field formed by the second collimator hole (the left side seen in the figure), the middle curve segment represents the dose intensity data distribution of the radiation field formed by the first collimator hole located in the central area, and the right curve segment represents the dose intensity data distribution of the radiation field formed by the first collimator hole (from the right side of the first collimator hole). Figure 5 Dose intensity data distribution of the radiation field formed by the second collimation hole (seen on the right).

[0058] (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 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 respectively represent 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, 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 NM.

[0059] (5) Calculate the pixel width difference data set y 3 The average of all pixel width differences corresponding to the range of 30% to 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% ). The numerical range of NM obtained in the previous step (pixel width difference data set y 3 ), further extract the corresponding pixel width difference data set x according to the value range 30%~40% corresponding to the middle area of ​​the curve segment in the longitudinal direction 3 The final value of NM determined by the mean value L of this part of pixel width difference data can accurately characterize the pixel width of the radiation field, and then calculate the accurate offset distance and angle.

[0060] (6) Calculate the horizontal offset OO of the target center* =P*L / {2*[(h SDD -h SCD ) / h SCD -(h SDD -h SID ) / h SID ], direction by OO * Positive and negative values ​​are determined.

[0061] (7) Find the normalized expanded dataset y 2 The x corresponding to the 100% value 1 value, assuming that x 1 The value is x 1 θ , the pixel coordinate corresponding to the EPID center is known as x 1 CAX , then the angle of inclination (inclination angle) of the target center is θ=arctan(|(x 1 θ -x 1 CAX ) / h SDD |), the direction is determined by (x 1 θ -x 1 CAX )The positive and negative values ​​are determined.

[0062] Embodiment 4 The present embodiment relates to a medical accelerator beam centering adjustment device. The implementation details of the medical accelerator beam centering adjustment device of the present embodiment are specifically described below. The following content is only for the convenience of understanding the implementation details, and is not necessary for the implementation of the present solution. The schematic diagram of the medical accelerator beam centering adjustment device of the present embodiment can be as follows: Fig. 9 As shown, it includes a data acquisition module 801, a data extraction module 802, an offset calculation module 803 and an offset adjustment module 804.

[0063] The data acquisition module 801 is used to acquire the dose intensity distribution data obtained by the electronic portal imaging device in the above-mentioned embodiment.

[0064] The data extraction module 802 is used to extract the dose intensity distribution data sets on the bed entry and exit direction lines and the left and right direction lines on the upper surface of the electronic portal imaging device from the dose intensity distribution data.

[0065] The offset calculation module 803 is used to calculate 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 based on the dose intensity distribution data set on the bed entry and exit direction line and the left and right direction line.

[0066] The offset adjustment module 804 is used to 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.

[0067] In some specific implementations, the dose intensity distribution data set 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 an electronic portal imaging device, and the extracted dose intensity distribution data set includes a dose intensity distribution data set on a bed in and out direction line and a dose intensity distribution data set on a left and right direction line.

[0068] Further, based on the dose intensity distribution data set, the offset distance and offset angle of the target center are calculated, including: representing the dose intensity distribution data set as a distribution curve, with the horizontal axis representing pixels and the vertical axis representing dose intensity data; based on the width P of a single pixel, the difference in pixel width (NM) of the radiation field generated by the second collimating holes on the left and right sides of the first collimating 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 from the target center to the bottom surface of the centering collimator h SID , the distance from the target center to the bottom of the primary collimator h SCD , calculate the offset distance OO of the target center * ; Based on the offset distance of the center line of the radiation field and the distance c from the target center to the upper surface of the electronic portal imaging device, the offset angle θ of the target center is calculated.

[0069] by Figure 6 Taking the example shown in the figure, the horizontal offset distance of the target center can be calculated by the following formula OO * =P*(NM) / {2*[(h SDD -h SCD ) / h SCD -(h SDD -h SID ) / h SID ]}.

[0070] 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.

[0071] NM can be calculated through post-processing of the collected data, so that the offset (offset distance) and offset direction of the beam target center can be calculated through the distribution of the radiation field (the positive and negative signs of the results represent the direction information, if NM is positive, it will be offset to the left, and if NM is negative, it will be offset to the right). The calculation accuracy does not depend on the positioning deviation of the EPID, thus reducing the mechanical positioning accuracy requirements for the EPID.

[0072] To calculate the offset angle of the target center, the following formula can be used: 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.

[0073] In this way, the tilt angle value and tilt direction of the beam targeting are calculated through the distribution of the radiation field (the positive and negative signs represent the angle direction information, the positive sign indicates a leftward shift, and the negative sign indicates a rightward shift).

[0074] In some specific implementations, before calculating the offset distance of the target center, the method further includes: (1) Normalize the ordinate value of the distribution curve to obtain a ordinate normalized data set; (2) Expanding the abscissa values ​​of the distribution curve to obtain an abscissa expanded data set, and calculating a ordinate normalized expanded data set corresponding to the abscissa expanded data set based on the ordinate normalized data set, the abscissa expanded data set, and the original abscissa values ​​of the distribution curve; (3) Generate a vertical coordinate generation data set with a preset normalized value as a preset interval that satisfies the normalized value range of the first vertical coordinate; determine a 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 a 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 vertical coordinate generation data set, the horizontal coordinate expansion data set and the vertical coordinate normalized expansion data set, respectively 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, calculate the horizontal coordinate generation data set corresponding to the vertical coordinate generation data set; (4) generating a data set based on the horizontal coordinate, calculating the pixel width difference between the first curve segment and the second curve segment, and obtaining a pixel width difference data set; (5) Calculate the mean of all pixel width differences corresponding to the normalized value range of the second ordinate in the pixel width difference data set, and determine the mean as the difference in pixel widths of the radiation fields generated by the second collimating holes on the left and right sides on the distribution curve; wherein the normalized value range of the second ordinate is smaller than the normalized value range of the first ordinate.

[0075] In some specific implementations, before calculating the offset angle of the target center, the method further includes: Determine the target abscissa value in the abscissa expanded data set corresponding to 100% in the ordinate normalized expanded data set; Based on the coordinates of the center point on the upper surface of the electronic portal imaging device and the target horizontal coordinate value, the offset angle of the target center is calculated.

[0076] In this embodiment, a dose intensity distribution data set on the bed entry and exit direction line and a dose intensity distribution data set on the left and right direction line are involved. Therefore, there are corresponding distribution curves corresponding to the bed entry and exit direction line and the left and right direction line respectively. The first distribution curve is drawn using the dose intensity data corresponding to each pixel on the bed entry and exit direction line, and the second distribution curve is drawn using the dose intensity data corresponding to each pixel on the left and right direction line.

[0077] It is worth mentioning that all modules involved in this embodiment are logic modules. In practical applications, a logic unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. In addition, in order to highlight the innovative part of the present invention, this embodiment does not introduce units that are not closely related to solving the technical problem proposed by the present invention, but this does not mean that there are no other units in this embodiment.

[0078] Embodiment 5 This embodiment provides a medical accelerator beam centering adjustment method, which is implemented based on a medical accelerator beam centering test device. The medical accelerator beam centering test device, such as Figure 1 As shown, including: A primary collimator 101 is arranged in the direction of the ray beam generated at the target center; The centering collimator 102 is arranged on the side of the primary collimator away from the target 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 both sides of the first collimation hole. The center of the first collimation hole and the centers of the two second collimation holes are collinear. The ray beam passes through the initial collimator and the centering collimator in sequence to form a three-part 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.

[0079] 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 and obtain the dose intensity distribution data used for the centering adjustment of the medical accelerator beam. The upper surface of the electronic portal imaging device is provided with a bed in-and-out direction line 106 and a left-right direction line 107. The bed in-and-out direction line 106 of the electronic portal imaging device 104 coincides with the laser line in the bed in-and-out 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, so as to perform a beam centering test.

[0080] The medical accelerator beam centering adjustment method comprises: Step 301 : collecting dose intensity distribution data obtained by an electronic portal imaging device.

[0081] Specifically, the ray beam generated at the target center passes through the initial collimator and the centering collimator in sequence to form a three-part radiation field. The electronic portal imaging device images the radiation field and obtains the dose intensity distribution data used for centering adjustment of the medical accelerator beam.

[0082] Step 302, extracting the dose intensity on the bed entry and exit direction line and the left and right direction line set on the upper surface of the electronic portal imaging device from the dose intensity distribution data, and obtaining a first dose intensity distribution data set on the bed entry and exit direction line and a second dose intensity distribution data set on the left and right direction line.

[0083] Step 303 , based on the first dose intensity distribution data set and the second dose intensity distribution data set, calculate 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.

[0084] In a specific implementation, step 303 further includes: Step 303a, representing both the first dose intensity distribution data set and the second dose intensity distribution data set with distribution curves, where the abscissa represents pixels and the ordinate represents dose intensity data, to obtain a first distribution curve and a second distribution curve; Step 303b, based on the width P of a single pixel, the difference in pixel width (NM) between the radiation fields generated by the second collimating holes on the left and right sides of the first collimating hole on the distribution curve, and the distance h from the center of the target to the upper surface of the electronic portal imaging device SDD , the distance from the target center to the bottom surface of the centering collimator h SID , the distance from the target center to the bottom of the primary collimator h SCD , calculate the offset distance OO of the target center * ; The horizontal offset distance of the target center can be calculated by the following formula OO * =P*(NM) / {2*[(h SDD -hSCD ) / h SCD -(h SDD -h SID ) / h SID ]}.

[0085] 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.

[0086] Step 303c: Calculate the offset angle θ of the target center 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.

[0087] To calculate the offset angle of the target center, the following formula can be used: 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.

[0088] In this way, the tilt angle value and tilt direction of the beam targeting are calculated through the distribution of the radiation field (the positive and negative signs represent the angle direction information, the positive sign indicates a leftward shift, and the negative sign indicates a rightward shift).

[0089] Step 304 , adjusting 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.

[0090] The method of this embodiment quantitatively solves the offset distance and tilt angle value of the electron target center from the source, and then corrects it through mechanical adjustment. Therefore, it only needs to be tested and calibrated once after the accelerator product is installed or the beam module is replaced to ensure that the symmetry of the later radiation field always meets the requirements. The test and adjustment accuracy only depends on the installation and positioning accuracy of the centering collimator relative to the primary collimator. This positioning accuracy is easy to ensure mechanically, so the method is very accurate and reliable. At the same time, this method does not introduce additional equipment and software into the product, but only exists in the form of tooling, which reduces product cost and increases product reliability. In summary, this method realizes a beam centering test and adjustment method that is both reliable and low-cost.

[0091] Embodiment 6 This embodiment provides a medical accelerator beam centering adjustment method, which is implemented based on a medical accelerator beam centering test device. The medical accelerator beam centering test device, such as Figure 1 As shown, including: A primary collimator 101 is arranged in the direction of the ray beam generated at the target center; The centering collimator 102 is arranged on the side of the primary collimator away from the target 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 both sides of the first collimation hole. The center of the first collimation hole and the centers of the two second collimation holes are collinear. The ray beam passes through the initial collimator and the centering collimator in sequence to form a three-part 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.

[0092] 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 and obtain the dose intensity distribution data used for the centering adjustment of the medical accelerator beam. The upper surface of the electronic portal imaging device is provided with a bed in-and-out direction line 106 and a left-right direction line 107. The bed in-and-out direction line 106 of the electronic portal imaging device 104 coincides with the laser line in the bed in-and-out 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, so as to perform a beam centering test.

[0093] The medical accelerator beam centering adjustment method comprises: Step 401 : collecting dose intensity distribution data obtained by an electronic portal imaging device, and extracting dose intensity distribution data sets on a bed entry and exit direction line and a left and right direction line set on an upper surface of the electronic portal imaging device from the dose intensity distribution data.

[0094] Step 402, normalizing the ordinate value of the distribution curve to obtain a ordinate normalized data set; Step 403, expanding the abscissa value of the distribution curve to obtain an abscissa expanded data set; Step 404: Calculate the ordinate normalized expanded data set corresponding to the abscissa expanded data set based on the ordinate normalized data set, the abscissa expanded data set and the original abscissa value of the distribution curve; Step 405, generating a vertical coordinate generation data set with a preset normalized value as a preset interval that meets the first vertical coordinate normalized value range; Step 406, determining a 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 a 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 ordinate generation data set, the abscissa expansion data set, and the ordinate normalization expansion data set, respectively 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, calculate the abscissa generation data set corresponding to the ordinate generation data set; Step 407, based on the horizontal coordinate, a data set is generated, and the pixel width difference between the first curve segment and the second curve segment is calculated to obtain a pixel width difference data set; the mean of all pixel width differences corresponding to the second vertical coordinate normalized value range in the pixel width difference data set is calculated, and the mean is determined as the difference in pixel widths of the radiation fields respectively generated by the second collimating holes on the left and right sides on the distribution curve; wherein the second vertical coordinate normalized value range is smaller than the first vertical coordinate normalized value range.

[0095] Step 408, determine the target abscissa value in the abscissa expansion data set corresponding to 100% in the ordinate normalized expansion data set, and calculate the offset angle of the target center based on the coordinates of the center point on the upper surface of the electronic portal imaging device and the target abscissa value.

[0096] Step 409: 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.

[0097] The following is an example to illustrate the calculation process of the offset distance and offset angle of the target center: (1) Using the formula y 1 =y / MAX(y)*100, normalize the ordinate value y of the distribution curve to obtain the ordinate normalized data set y 1 The normalized vertical axis values ​​(dose intensity data) are percentage data.

[0098] (2) Expand the horizontal coordinate value x of the distribution curve by doubling it to obtain the horizontal coordinate expanded data set x 1, based on the normalized dataset y 1 , the horizontal axis expands the data set x 1 and the original horizontal coordinate value x of the distribution curve, calculate the horizontal coordinate expansion data set x 1 The corresponding ordinate normalized expanded data set y 2 .

[0099] For example, the original horizontal axis values ​​are 0, 100, 200, ..., and after doubling, the horizontal axis values ​​are 0, 50, 100, 150, 200, ... Based on the linear regression of the data set, calculate the horizontal axis expansion data set x 1 The budget of the vertical coordinate normalized expansion data set y 2 =FORECAST(x 1 ,y 1 ,x).

[0100] (3) The normalized value range of the first vertical axis is 30% to 80%, which is the area in the dose intensity data set on the distribution curve. A set of vertical axes with intervals of 0.1% from 30% to 80% is generated to generate the data set y 3 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 linear regression of the data set, calculate the ordinate to generate the data set y for 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, and the rising part (curve corresponding to the right_1 data set) and the falling part (curve corresponding to the right_2 data set) of the second curve segment. 3 The horizontal axis of the budget generates the data set x 2 =FORECAST(y 3 ,x 1 ,y 2 ). Here, from Figure 6 , 7 It 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 dose intensity data distribution on the left side of the first collimator hole (from Figure 5 The dose intensity data distribution of the radiation field formed by the second collimator hole (the left side seen in the figure), the middle curve segment represents the dose intensity data distribution of the radiation field formed by the first collimator hole located in the central area, and the right curve segment represents the dose intensity data distribution of the radiation field formed by the first collimator hole (from the right side of the first collimator hole). Figure 5 Dose intensity data distribution of the radiation field formed by the second collimation hole (seen on the right).

[0101] (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 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 respectively represent 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, 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 NM.

[0102] (5) Calculate the pixel width difference data set y 3 The average of all pixel width differences corresponding to the range of 30% to 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% ). The numerical range of NM obtained in the previous step (pixel width difference data set y 3 ), further extract the corresponding pixel width difference data set x according to the value range 30%~40% corresponding to the middle area of ​​the curve segment in the longitudinal direction 3 The final value of NM determined by the mean value L of this part of pixel width difference data can accurately characterize the pixel width of the radiation field, and then calculate the accurate offset distance and angle.

[0103] (6) Calculate the horizontal offset OO of the target center * =P*L / {2*[(h SDD -h SCD ) / h SCD -(h SDD -h SID ) / h SID ], direction by OO * Positive and negative values ​​are determined.

[0104] (7) Find the normalized expanded dataset y 2 The x corresponding to the 100% value 1 value, assuming that x 1 The value is x 1 θ , the pixel coordinate corresponding to the EPID center is known as x 1 CAX , then the angle of inclination (inclination angle) of the target center is θ=arctan(|(x 1 θ -x 1 CAX ) / h SDD |), the direction is determined by (x 1 θ -x 1 CAX )The positive and negative values ​​are determined.

[0105] The method of this embodiment quantitatively solves the offset distance and tilt angle value of the electron target center from the source, and then corrects it through mechanical adjustment. It only needs to be tested and calibrated once after the accelerator product is installed or the beam module is replaced to ensure that the symmetry of the later radiation field always meets the requirements. The test and adjustment accuracy only depends on the installation and positioning accuracy of the centering collimator relative to the primary collimator. This positioning accuracy is easy to ensure mechanically, so the method is very accurate and reliable. At the same time, this method does not introduce additional equipment and software into the product, but only exists in the form of tooling, which reduces product cost and increases product reliability. In summary, this method realizes a beam centering test and adjustment method that is both reliable and low-cost.

[0106] Embodiment 7 This embodiment provides an electronic device, including: at least one processor; and, a memory communicatively connected to at least one processor; wherein, The memory stores instructions that can be executed by 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 medical accelerator beam centering adjustment method.

[0107] Among them, the memory and the processor are connected in a bus manner, and the bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors and memories together. The bus can also connect various other circuits such as peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices on a transmission medium. The data processed by the processor is transmitted on a wireless medium via an antenna, and further, the antenna also receives data and transmits the data to the processor.

[0108] The processor is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory can be used to store data used by the processor when performing operations.

[0109] Embodiment 8 This embodiment provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the above-mentioned medical accelerator beam centering adjustment method is implemented.

[0110] Those skilled in the art can understand that all or part of the steps in the above-mentioned embodiments can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions for making a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, referred to as: ROM), random access memory (Random Access Memory, referred to as: RAM), disk or optical disk and other media that can store program codes.

[0111] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present invention, and that in actual applications, various changes may be made in form and detail 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 initial 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 passes through the initial collimator and the centering collimator in sequence 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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