Three-dimensional correction method and system for medical linear accelerator beam limiting device

Abstract

The invention discloses a three-dimensional correction method and system for a medical linear accelerator beam limiting device, and the method comprises the steps: collecting a radiation field image generated by a medical linear accelerator; actual position information of the beam limiting device is obtained through processing and calculation based on the radiation field image, difference analysis is carried out on the actual position information of the beam limiting device and target position information, and a motion correction file is generated; and correcting the motion position of the beam limiting device according to the difference value information in the motion correction file. According to the method, the radiation field image generated by the medical linear accelerator is collected, the radiation field image is processed and analyzed to obtain the deviation between the actual position information and the target position information of the beam limiting device, the correction file is generated, the control system of the medical linear accelerator receives the correction file and analyzes the correction file, and automatic correction of the beam limiting device is achieved. And the movement in-place precision of the beam limiting device is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of radiotherapy equipment, and in particular to a three-dimensional correction method and system for a beam limiting device of a medical linear accelerator. Background Art

[0002] In the current medical industry, in order to improve the treatment efficiency of medical linear accelerators, beam limiting devices (gratings and tungsten gates) are usually used to adjust the irradiation range and shape of the radiation, optimize the dose distribution, ensure that the radiation only irradiates the area that needs treatment, and reduce the leakage dose of normal tissues to meet the treatment needs of different patients and tumors. Therefore, the accuracy of the beam limiting device is of great significance to the accuracy and effect of accelerator radiotherapy.

[0003] For medical linear accelerators, there are three methods to detect the accuracy of the beam limiting device:

[0004] The first method, the Picket Fence planning method, generates an execution plan containing multiple narrow fields (Picket Fence) on the treatment planning system, sends the plan to the linear accelerator for execution, and uses a dose monitor to record the dose distribution at different positions. The accuracy of the beam limiting device is evaluated by observing the consistency of the field shape and size with the plan, as well as the uniformity of the dose distribution.

[0005] The second method, the film analysis method, places the film in a specific position, adjusts the irradiation parameters, applies the planning system, forms a specific number of MLC fence fields on the film, measures the field width and center position of each fence field, scans the irradiated film with a scanning device, and uses dedicated software for analysis.

[0006] The third method, image analysis, places the EPID (electronic planar imaging device) in the appropriate position and calibrates it with a laser to ensure that the beam limiter is aligned with the EPID imaging. The field plan designed in the treatment planning system is sent to the accelerator for execution, and the images captured by the EPID are collected using a dedicated DAS acquisition program and then imported into dedicated image processing software for analysis.

[0007] However, the above three methods all have problems and defects:

[0008] Problems and defects of the first method: (1) The placement and positioning of the dose monitor requires the use of a laser locator to ensure its accurate position and alignment with the central axis of the accelerator, which may be affected by human factors and lead to measurement errors; (2) The Picket Fence planning method requires the generation of a specific field plan, followed by image acquisition and analysis. The entire process takes a long time, affecting efficiency.

[0009] Problems and defects of the second method: (1) The film analysis method requires precise placement of the film, adjustment of irradiation parameters, irradiation, film scanning, and subsequent analysis. The operation is relatively complicated and requires professional personnel; (2) The entire process including irradiation, film development, scanning, and data analysis takes a long time and may affect the treatment efficiency; (3) It is easily affected by the subjectivity of the operator, such as film placement, irradiation parameter adjustment, etc.

[0010] The problems and defects of the third method are: it requires multiple rounds of operations using multiple software and analysis using dedicated image processing software, which is complicated and time-consuming.

[0011] In view of this, the present invention mainly solves the problem that the beam limiting device of a medical linear accelerator causes the shape and size of the rays to be inaccurate with the actual ones at different racks and collimator angles due to assembly problems, and the positioning accuracy of the grating and tungsten gate is deviated. Summary of the invention

[0012] In order to solve the above problems, the present invention provides a three-dimensional correction method and system for a medical linear accelerator beam limiting device. Specifically, the following technical solutions are adopted:

[0013] A three-dimensional correction method for a medical linear accelerator beam limiting device, comprising:

[0014] Collect the portal images produced by medical linear accelerator;

[0015] Based on the portal image processing calculation, actual position information of the beam limiting device is obtained, and difference analysis is performed between the actual position information of the beam limiting device and the target position information to generate a motion correction file;

[0016] According to the difference information in the motion correction file, the motion position of the beam limiting device is corrected.

[0017] As an optional embodiment of the present invention, in a three-dimensional correction method for a medical linear accelerator beam limiting device of the present invention, the actual position information of the beam limiting device is obtained based on the portal image processing calculation, and the actual position information of the beam limiting device is subjected to difference analysis with the target position information to generate a motion correction file, which includes:

[0018] The radiation field images of the medical linear accelerator at different gantry angles g and different collimator angles c are collected respectively;

[0019] A difference set {E(g, c, p)} of the beam limiting device position p is calculated based on each of the portal images.

[0020] As an optional embodiment of the present invention, in a three-dimensional correction method for a medical linear accelerator beam limiting device of the present invention, for any gantry angle and collimator angle of the medical linear accelerator, the calculation process of obtaining the difference parameter E (g, c, p) includes:

[0021] According to the collimator angle, the portal image is rotated to the standard direction, that is, the left side of the portal image after rotation is consistent with the left side when the collimator is 0°;

[0022] Within the range of the beam limiting device forming the portal image, for each row i, find the highlighted area in the row and calculate the centroid coordinate x of the highlighted area, which is the actual x-coordinate position of the beam limiting component. Assume that the target x-coordinate position of the beam limiting component is x * , then the x-coordinate difference parameter is x * -x;

[0023] Within the range of the beam limiting device forming the portal image, for each row j, find the highlighted area in the column and calculate the centroid coordinate y of the highlighted area, which is the actual y coordinate position of the beam limiting component. Assume that the target position of the beam limiting component is y * , then the y coordinate difference is y * -y;

[0024] The x coordinate difference parameter y * -y and y coordinates are different by y * -y constitutes the difference coordinates, which are the difference parameters E(g, c, p) corresponding to any gantry angle and collimator angle of the medical linear accelerator.

[0025] As an optional embodiment of the present invention, in a three-dimensional correction method of a medical linear accelerator beam limiting device of the present invention, within the range of the beam limiting device forming the portal image, for each row i, a highlighted area in the row is found, and the centroid coordinate x of the highlighted area is calculated, which is the actual x coordinate position of the beam limiting component. Assuming that the target x coordinate position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x include:

[0026] When the beam limiting component of the beam limiting device is located on the left side of the portal image, and the beam limiting component moves left and right;

[0027] Within the upper and lower range of the beam limiting device to form the projection image, for each row i, find the position x with the maximum brightness in the row. i , and its brightness I max =max(I(i,j));

[0028] By x i Look to the right for brightness The position x half i ;

[0029] The actual position of the beam limiting component is obtained by averaging x = average (x half i );

[0030] Assume that the target position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x.

[0031] As an optional embodiment of the present invention, in a three-dimensional correction method of a medical linear accelerator beam limiting device of the present invention, within the range of the beam limiting device forming the portal image, for each row i, a highlighted area in the row is found, and the centroid coordinate x of the highlighted area is calculated, which is the actual x coordinate position of the beam limiting component. Assuming that the target x coordinate position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x includes: when the beam limiting component of the beam limiting device is located on the right side of the portal image, and the beam limiting component moves left and right;

[0032] Within the upper and lower range of the beam limiting device to form the projection image, for each row i, find the position x with the maximum brightness in the row. i , and its brightness I max = max(I(i, j));

[0033] By x i Look left for brightness The position x half i ;

[0034] The actual position of the beam limiting component is obtained by averaging x = average (x half i );

[0035] Assume that the target position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x.

[0036] As an optional embodiment of the present invention, in a three-dimensional correction method of a medical linear accelerator beam limiting device of the present invention, within the range of the beam limiting device forming the portal image, for each row j, the highlighted area in the column is found, and the centroid coordinate y of the highlighted area is calculated, which is the actual y coordinate position of the beam limiting component. Assuming that the target position of the beam limiting component is y * , then the y coordinate difference is y * -y includes:

[0037] When the beam limiting component of the beam limiting device is located on the upper side of the portal image, and the beam limiting component moves up and down;

[0038] Within the upper and lower range of the beam limiting device to form the projection image, for each column j, find the position y with the maximum brightness in the row i , and its brightness I max =max(I(i,j));

[0039] , by y i Look down for brightness The position y half i ;

[0040] The actual position of the beam limiting component is obtained by averaging y = average (y half i );

[0041] Assume that the target position of the constrained component is y * , then the y coordinate difference is y * -y.

[0042] As an optional embodiment of the present invention, in a three-dimensional correction method of a medical linear accelerator beam limiting device of the present invention, within the range of the beam limiting device forming the portal image, for each row j, the highlighted area in the column is found, and the centroid coordinate y of the highlighted area is calculated, which is the actual y coordinate position of the beam limiting component. Assuming that the target position of the beam limiting component is y * , then the y coordinate difference is y * -y includes:

[0043] When the beam limiting component of the beam limiting device is located at the lower side of the portal image, and the beam limiting component moves up and down;

[0044] Within the upper and lower range of the beam limiting device to form the projection image, for each column j, find the position y with the maximum brightness in the row i , and its brightness I max =max(I(i,j));

[0045] , by y i Look down for brightness The position y half i ;

[0046] The actual position of the beam limiting component is obtained by averaging y = average (y half i );

[0047] Assume that the target position of the constrained component is y * , then the y coordinate difference is y *As an optional embodiment of the present invention, in a three-dimensional correction method for a medical linear accelerator beam limiting device of the present invention, the correction of the motion position of the beam limiting device according to the difference information in the motion correction file includes:

[0048] Obtain the target gantry position and target straightener angle of the medical linear accelerator;

[0049] According to the target gantry position and the target straightener angle, the corresponding beam limiting component difference parameters are obtained from the difference set {E(g, c, p)} of the beam limiting device position p in the motion correction file;

[0050] The target operating parameters of the beam limiting component are corrected according to the beam limiting component difference parameters and sent to the motion device to achieve in-place correction of the beam limiting device.

[0051] The present invention also provides a three-dimensional correction system for a medical linear accelerator beam limiting device for implementing the three-dimensional correction method, comprising:

[0052] A portal image acquisition module, which acquires portal images generated by a medical linear accelerator;

[0053] A three-dimensional correction module, which obtains the actual position information of the beam limiting device based on the portal image processing calculation, performs a difference analysis between the actual position information of the beam limiting device and the target position information, and generates a motion correction file;

[0054] The accelerator control module corrects the motion position of the beam limiting device according to the difference information in the motion correction file.

[0055] As an optional embodiment of the present invention, the portal image acquisition module is a two-dimensional flat-panel detector, which is arranged on the frame of the medical linear accelerator and changes its position as the frame rotates. The two-dimensional flat-panel detector is perpendicular to the beam center of the medical linear accelerator and faces the beam direction of the medical linear accelerator.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] The three-dimensional correction method of a beam-limiting device of a medical linear accelerator of the present invention mainly solves the problem that the grating and tungsten gate of the beam-limiting device in the medical linear accelerator are not accurately positioned due to assembly at different racks and collimator angles, and the displayed beam position has errors. The three-dimensional correction method of a beam-limiting device of a medical linear accelerator of the present invention collects the field image generated by the medical linear accelerator, and processes and analyzes the field image to obtain the deviation between the actual position information of the beam-limiting device and the target position information, and generates a correction file. The control system of the medical linear accelerator receives the correction file for analysis, realizes automatic correction of the beam-limiting device, and improves the movement accuracy of the beam-limiting device.

[0058] Compared with the existing technology, the three-dimensional correction method of the medical linear accelerator beam limiting device of the present invention brings two beneficial effects:

[0059] (1) It can improve work efficiency and reduce multiple rounds of operations. There is no need to use dedicated image processing software to analyze the position of the beam limiting device. The three-dimensional correction method of the medical linear accelerator beam limiting device of this embodiment can perform difference analysis and correction on the position of the beam limiting device.

[0060] (2) Reducing the control error caused by the control process. There is no need to manually position additional detection equipment and calibrate the virtual position laser light, which can reduce the human factor error caused by the process. The three-dimensional correction method of a medical linear accelerator beam limiting device in this embodiment does not require the use of an additional dose monitor and can perform automatic collection and correction. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 Process of a three-dimensional correction method for a beam limiting device of a medical linear accelerator according to an embodiment of the present invention Figure 1 ;

[0062] Figure 2 Process of a three-dimensional correction method for a beam limiting device of a medical linear accelerator according to an embodiment of the present invention Figure 2 ;

[0063] Figure 3 A system diagram of a three-dimensional correction system for a beam limiting device of a medical linear accelerator according to an embodiment of the present invention;

[0064] Figure 4 A schematic diagram of the installation of a two-dimensional flat panel detector of a three-dimensional correction system of a beam limiting device for a medical linear accelerator according to an embodiment of the present invention. DETAILED DESCRIPTION

[0065] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0066] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents some embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0067] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0068] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0069] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed when in use, or the orientation or positional relationship commonly understood by those skilled in the art. Such terms are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0070] See also Figure 1 As shown, a three-dimensional correction method for a medical linear accelerator beam limiting device of this embodiment includes:

[0071] Collect the portal images produced by medical linear accelerator;

[0072] Based on the portal image processing calculation, actual position information of the beam limiting device is obtained, and difference analysis is performed between the actual position information of the beam limiting device and the target position information to generate a motion correction file;

[0073] According to the difference information in the motion correction file, the motion position of the beam limiting device is corrected.

[0074] A three-dimensional correction method for a beam limiting device of a medical linear accelerator in this embodiment mainly solves the problem that the grating and tungsten gate of the beam limiting device in the medical linear accelerator are not accurately positioned due to assembly at different racks and collimator angles, and the displayed beam position has errors. A three-dimensional correction method for a beam limiting device of a medical linear accelerator in this embodiment collects the field image generated by the medical linear accelerator, and processes and analyzes the field image to obtain the deviation between the actual position information of the beam limiting device and the target position information, generates a correction file, and the control system of the medical linear accelerator receives the correction file for analysis, realizes automatic correction of the beam limiting device, and improves the movement accuracy of the beam limiting device.

[0075] Compared with the existing technology, the three-dimensional correction method of a medical linear accelerator beam limiting device of this embodiment brings two beneficial effects:

[0076] (1) It can improve work efficiency and reduce multiple rounds of operations. There is no need to use dedicated image processing software to analyze the position of the beam limiting device. The three-dimensional correction method of the medical linear accelerator beam limiting device of this embodiment can perform difference analysis and correction on the position of the beam limiting device.

[0077] (2) Reducing the control error caused by the control process. There is no need to manually position additional detection equipment and calibrate the virtual position laser light, which can reduce the human factor error caused by the process. The three-dimensional correction method of a medical linear accelerator beam limiting device in this embodiment does not require the use of an additional dose monitor and can perform automatic collection and correction.

[0078] Furthermore, in a three-dimensional correction method for a beam limiting device of a medical linear accelerator of this embodiment, the actual position information of the beam limiting device is obtained based on the portal image processing calculation, and the actual position information of the beam limiting device is subjected to difference analysis with the target position information to generate a motion correction file, including:

[0079] The radiation field images of the medical linear accelerator at different gantry angles g and different collimator angles c are collected respectively;

[0080] A difference set {E(g, c, p)} of the beam limiting device position p is calculated based on each of the portal images.

[0081] In this embodiment, by collecting the field images of the medical linear accelerator at different gantry angles g and different collimator angles c, a difference set {E(g, c, p)} of the position p of the beam limiting device is obtained. Thus, in the actual working process of the medical linear accelerator, after the target gantry angle g and the target collimator angle c of the medical linear accelerator are determined, the corresponding difference parameter E(g, c, p)} of the position p of the beam limiting device can be obtained. The medical linear accelerator can realize the motion correction of the beam limiting device according to the difference parameter E(g, c, p), and there is no need to use dedicated image processing software to analyze the position of the beam limiting device, which can improve work efficiency and reduce multiple rounds of operations.

[0082] Specifically, in a three-dimensional correction method for a medical linear accelerator beam limiting device of this embodiment, for any gantry angle and collimator angle of the medical linear accelerator, the calculation process of obtaining the difference parameter E(g, c, p) includes:

[0083] According to the collimator angle, the portal image is rotated to the standard direction, that is, the left side of the portal image after rotation is consistent with the left side when the collimator is 0°;

[0084] Within the range of the beam limiting device forming the portal image, for each row i, find the highlighted area in the row and calculate the centroid coordinate x of the highlighted area, which is the actual x-coordinate position of the beam limiting component. Assume that the target x-coordinate position of the beam limiting component is x * , then the x-coordinate difference parameter is x * -x;

[0085] Within the range of the beam limiting device forming the portal image, for each row j, find the highlighted area in the column and calculate the centroid coordinate y of the highlighted area, which is the actual y coordinate position of the beam limiting component. Assume that the target position of the beam limiting component is y * , then the y coordinate difference is y * -y;

[0086] The x coordinate difference parameter y * The difference between -y and y coordinates is y * -y constitutes the difference coordinates, which are the difference parameters E(g, c, p) corresponding to any gantry angle and collimator angle of the medical linear accelerator.

[0087] This embodiment uses the centroid of the highlighted area in the portal image to represent the actual position of the beam, which is based on the correspondence between the image brightness and the X-ray energy distribution in the X-ray device in the medical imaging device, and the centroid calculation can provide a stable and accurate geometric center of the beam area.

[0088] The centroid calculation relies on a basic mathematical model, which considers the highlight area as a mass distribution on a two-dimensional plane (the distribution of pixel brightness values ​​in an image). The centroid (or center of gravity) is the geometric center of the distribution, and the specific calculation method is as follows:

[0089] For an image matrix, each pixel has a position (x, y) and a corresponding brightness value I(x, y). The higher the brightness value of a pixel, the greater the influence of the rays on that position. The brightness value is positively correlated with the energy distribution of the rays.

[0090] The formula for calculating the centroid is:

[0091] xcenter=∑(x·I(x,y)) / ∑I(x,y)

[0092] ycenter=∑(y·I(x,y)) / ∑I(x,y)

[0093] Among them, I(x,y) is the brightness value of each pixel in the image, and x and y are the coordinates of the pixel. This formula means that the higher the brightness value of the pixel, the greater the influence of the center of mass position on the accurate acquisition of the coordinates and mass (or weight) of each point in the graph, that is, the weighted average of the brightness.

[0094] This calculation does not depend on the specific shape or size of the graphic object. As long as the coordinates and mass (or weight) of each point in the graphic can be accurately obtained, the center of mass position can be calculated. This method is highly robust. Changes in the shape of the image (such as rotation, scaling, deformation, etc.) will not have a significant impact on the calculated position. Moreover, the graphic object or image area can be treated as a mass point (i.e., the center of mass) for processing, which can greatly simplify the problem.

[0095] Specifically, in a three-dimensional correction method for a beam limiting device of a medical linear accelerator of this embodiment, within the range of the beam limiting device forming the portal image, for each row i, a highlighted area in the row is found, and the centroid coordinate x of the highlighted area is calculated, which is the actual x-coordinate position of the beam limiting component. Assuming that the target x-coordinate position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x include:

[0096] When the beam limiting component of the beam limiting device (such as the left tungsten block of the tungsten gate) is located on the left side of the portal image, and the beam limiting component moves left and right;

[0097] In the upper and lower range of the beam limiting device forming the projection field image, for each row i (for grating blades, the number of rows is small, which may be only a few rows; for tungsten gate components, the number of rows may reach dozens of rows), find the position x with the maximum brightness in the row. i , and its brightness I max =max(I(i,j));

[0098] By x i Look to the right for brightness The position x half i ;

[0099] The actual position of the beam limiting component is obtained by averaging x = average (x half i );

[0100] Assume that the target position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x.

[0101] In the three-dimensional correction method of a beam limiting device of a medical linear accelerator of this embodiment, within the range of the beam limiting device forming the portal image, for each row i, a highlighted area in the row is found, and the centroid coordinate x of the highlighted area is calculated, which is the actual x-coordinate position of the beam limiting component. Assuming that the target x-coordinate position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x include:

[0102] When the beam limiting component of the beam limiting device (such as the right tungsten block of the tungsten gate) is located on the right side of the portal image, and the beam limiting component moves left and right;

[0103] Within the upper and lower range of the beam limiting device to form the projection image, for each row i, find the position x with the maximum brightness in the row. i , and its brightness I max = max(I(i, j));

[0104] By x i Look left for brightness The position x half i ;

[0105] The actual position of the beam limiting component is obtained by averaging x = average (x half i );

[0106] Assume that the target position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x.

[0107] In the three-dimensional correction method of a beam limiting device of a medical linear accelerator of this embodiment, within the range of the beam limiting device forming the portal image, for each row j, the highlighted area in the column is found, and the centroid coordinate y of the highlighted area is calculated, which is the actual y coordinate position of the beam limiting component. Assuming that the target position of the beam limiting component is y * , then the y coordinate difference is y * -y includes:

[0108] When the beam limiting component of the beam limiting device is located on the upper side of the portal image (such as the tungsten block on the right side of the tungsten gate), and the beam limiting component moves up and down;

[0109] Within the upper and lower range of the beam limiting device to form the projection image, for each column j, find the position y with the maximum brightness in the row i , and its brightness I max = max(I(i, j));

[0110] , by y i Look down for brightness The position y half i ;

[0111] The actual position of the beam limiting component is obtained by averaging y = average (y half i );

[0112] Assume that the target position of the constrained component is y * , then the y coordinate difference is y * -y.

[0113] In the three-dimensional correction method of a beam limiting device of a medical linear accelerator of this embodiment, within the range of the beam limiting device forming the portal image, for each row j, the highlighted area in the column is found, and the centroid coordinate y of the highlighted area is calculated, which is the actual y coordinate position of the beam limiting component. Assuming that the target position of the beam limiting component is y * , then the y coordinate difference is y * -y includes: when the beam limiting component of the beam limiting device (such as the right tungsten block of the tungsten gate) is located at the lower side of the portal image, and the beam limiting component moves up and down;

[0114] Within the upper and lower range of the beam limiting device to form the projection image, for each column j, find the position y with the maximum brightness in the row i , and its brightness I max = max(I(i, j));

[0115] , by y i Look down for brightness The position y half i ;

[0116] The actual position of the beam limiting component is obtained by averaging y = average (y half i );

[0117] Assume that the target position of the constrained component is y * , then the y coordinate difference is y * -y.

[0118] See also Figure 2 As shown, in a three-dimensional correction method for a beam limiting device of a medical linear accelerator of this embodiment, the correction of the motion position of the beam limiting device according to the difference information in the motion correction file includes:

[0119] Obtain the target gantry position and target straightener angle of the medical linear accelerator;

[0120] According to the target gantry position and the target straightener angle, the corresponding beam limiting component difference parameters are obtained from the difference set {E(g, c, p)} of the beam limiting device position p in the motion correction file;

[0121] The target operating parameters of the beam limiting component are corrected according to the beam limiting component difference parameters and sent to the motion device to achieve in-place correction of the beam limiting device.

[0122] The control system of the medical linear accelerator in this embodiment receives the calibration file, obtains the difference of the beam limiter component of the moving target frame position, collimator angle, and beam limiter position, compensates the moving target according to the difference and sends it to the motion device, controls the motion control of the beam limiter, realizes the in-place correction of the grating and tungsten gate positions under different frames and collimator angles, and drives the beam limiter to move according to the adjusted beam limiter position.

[0123] See also Figure 3 As shown, this embodiment also provides a three-dimensional correction system for a medical linear accelerator beam limiting device for implementing the three-dimensional correction method, including:

[0124] A portal image acquisition module, which acquires portal images generated by a medical linear accelerator;

[0125] A three-dimensional correction module, which obtains the actual position information of the beam limiting device based on the portal image processing calculation, performs a difference analysis between the actual position information of the beam limiting device and the target position information, and generates a motion correction file;

[0126] The accelerator control module corrects the motion position of the beam limiting device according to the difference information in the motion correction file.

[0127] In this embodiment, a three-dimensional correction system for a medical linear accelerator beam limiting device is provided, and the working principles of each module are mainly as follows:

[0128] The portal image acquisition module is used to acquire portal images formed by rays passing through the grating and the tungsten threshold beam device.

[0129] The three-dimensional correction module is used to receive instructions sent from the accelerator control module. Once the tungsten gate and grating inspection item instructions in the accelerator control module are received, it starts to collect the field image generated by the medical linear accelerator.

[0130] The three-dimensional correction module mainly presents the field images of the grating and tungsten gate under different racks and collimator angles, calculates the position of the beam limiting device based on the image, performs difference analysis, obtains difference parameters, generates correction files, and feeds the correction files back to the accelerator control module through the network.

[0131] A three-dimensional correction system for a medical linear accelerator beam limiting device in this embodiment mainly comprises the following items:

[0132] The portal image acquisition module is a two-dimensional flat-panel detector installed on a medical linear accelerator;

[0133] A 3D calibration module consisting of 3D calibration software (3DCS) and a computer installed with the software is used to control the EPID to acquire the portal image and calculate the position of the beam limiting device based on the image to generate a calibration file;

[0134] The accelerator control module, which consists of the accelerator control software (Linac Control Software, LCS) and the computer installed with the software, is used to control the movement and beam output of the beam limiting device, and receive the correction file sent by the three-dimensional correction software to correct the position of the beam limiting device.

[0135] The two-dimensional flat-panel detector described in this embodiment is arranged on the frame of the medical linear accelerator. Its position changes with the rotation of the frame. The two-dimensional flat-panel detector is perpendicular to the beam center of the medical linear accelerator and faces the beam direction of the medical linear accelerator. It is used to collect the field image formed by the rays passing through the grating and the tungsten threshold beam device.

[0136] This embodiment also provides a computer-readable storage medium storing a computer-executable program. When the computer-executable program is executed, the three-dimensional correction method of the beam limiting device of a medical linear accelerator is implemented.

[0137] The computer-readable storage medium described in this embodiment may include a data signal propagated in a baseband or as part of a carrier wave, wherein a readable program code is carried. This propagated data signal may take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above. The computer-readable storage medium may also be any readable medium other than a readable storage medium, which may send, propagate, or transmit a program for use by or in combination with an instruction execution system, an apparatus, or a device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the above.

[0138] This embodiment also provides an electronic device, including a processor and a memory, wherein the memory is used to store a computer executable program, and when the computer program is executed by the processor, the processor executes the three-dimensional correction method of a medical linear accelerator beam limiting device.

[0139] The electronic device is presented in the form of a general-purpose computing device. The processor may be one or more than one and work in coordination. The present invention does not exclude distributed processing, that is, the processor may be dispersed in different physical devices. The electronic device of the present invention is not limited to a single entity, but may also be the sum of multiple physical devices.

[0140] The memory stores a computer executable program, which is usually a machine-readable code. The computer-readable program can be executed by the processor to enable the electronic device to perform the method of the present invention, or at least part of the steps in the method.

[0141] The memory includes a volatile memory, such as a random access memory unit (RAM) and / or a cache memory unit, and may also be a non-volatile memory, such as a read-only memory unit (ROM).

[0142] It should be understood that the electronic device of the present invention may also include elements or components not shown in the above examples. For example, some electronic devices also include display units such as display screens, and some electronic devices also include human-computer interaction elements such as buttons and keyboards. As long as the electronic device can execute the computer-readable program in the memory to implement the method of the present invention or at least part of the steps of the method, it can be considered as an electronic device covered by the present invention.

[0143] Through the above description of the implementation mode, it is easy for those skilled in the art to understand that the present invention can be implemented by hardware capable of executing a specific computer program, such as the system of the present invention, and the electronic processing unit, server, client, mobile phone, control unit, processor, etc. contained in the system. The present invention can also be implemented by computer software that executes the method of the present invention, such as control software executed by a microprocessor, an electronic control unit, a client, a server, etc. However, it should be noted that the computer software that executes the method of the present invention is not limited to being executed by one or a specific hardware entity, and it can also be implemented in a distributed manner by unspecified specific hardware. For computer software, the software product can be stored in a computer-readable storage medium (which can be a CD-ROM, a U disk, a mobile hard disk, etc.), and can also be distributed and stored on the network, as long as it can enable the electronic device to execute the method according to the present invention.

[0144] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the above specific implementation methods. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the invention are included in the scope of the claims of the present invention.

Claims

1. A three-dimensional correction method for a medical linear accelerator beam limiting device, characterized in that: include: Collect the portal images produced by medical linear accelerator; Based on the portal image processing calculation, actual position information of the beam limiting device is obtained, and difference analysis is performed between the actual position information of the beam limiting device and the target position information to generate a motion correction file; According to the difference information in the motion correction file, the motion position of the beam limiting device is corrected.

2. A three-dimensional correction method for a medical linear accelerator beam limiting device according to claim 1, characterized in that: The actual position information of the beam limiting device is obtained by calculation based on the portal image processing, and the actual position information of the beam limiting device is subjected to difference analysis with the target position information to generate a motion correction file, which includes: The radiation field images of the medical linear accelerator at different gantry angles g and different collimator angles c are collected respectively; A difference set {E(g, c, p)} of the beam limiting device position p is calculated based on each of the portal images.

3. A three-dimensional correction method for a medical linear accelerator beam limiting device according to claim 2, characterized in that: For any gantry angle and collimator angle of a medical linear accelerator, the calculation process of obtaining the difference parameter E(g, c, p) includes: According to the collimator angle, the portal image is rotated to the standard direction, that is, the left side of the portal image after rotation is consistent with the left side when the collimator is 0°; Within the range of the beam limiting device forming the portal image, for each row i, find the highlighted area in the row and calculate the centroid coordinate x of the highlighted area, which is the actual x-coordinate position of the beam limiting component. Assume that the target x-coordinate position of the beam limiting component is x * , then the x-coordinate difference parameter is x * -x; Within the range of the beam limiting device forming the portal image, for each row j, find the highlighted area in the column and calculate the centroid coordinate y of the highlighted area, which is the actual y coordinate position of the beam limiting component. Assume that the target position of the beam limiting component is y * , then the y coordinate difference is y * -y; The x coordinate difference parameter y * The difference between -y and y coordinates is y * -y constitutes the difference coordinates, which are the difference parameters E(g, c, p) corresponding to any gantry angle and collimator angle of the medical linear accelerator.

4. A three-dimensional correction method for a medical linear accelerator beam limiting device according to claim 3, characterized in that: Within the range of the beam limiting device forming the portal image, for each row i, the highlighted area in the row is found, and the centroid coordinate x of the highlighted area is calculated, which is the actual x coordinate position of the beam limiting component. Assuming that the target x coordinate position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x include: When the beam limiting component of the beam limiting device is located on the left side of the portal image, and the beam limiting component moves left and right; Within the upper and lower range of the beam limiting device to form the projection image, for each row i, find the position x with the maximum brightness in the row. i , and its brightness I max = max(I(i, j)); By x i Look to the right for brightness The position x half i ; The actual position of the beam limiting component is obtained by averaging x = average (x half i ); Assume that the target position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x.

5. The three-dimensional correction method of a medical linear accelerator beam limiting device according to claim 3, characterized in that: Within the range of the beam limiting device forming the portal image, for each row i, the highlighted area in the row is found, and the centroid coordinate x of the highlighted area is calculated, which is the actual x coordinate position of the beam limiting component. Assuming that the target x coordinate position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x includes: when the beam limiting component of the beam limiting device is located on the right side of the portal image, and the beam limiting component moves left and right; Within the upper and lower range of the beam limiting device to form the projection image, for each row i, find the position x with the maximum brightness in the row. i , and its brightness I max =max(I(i,j)); By x i Look left for brightness The position x half i ; The actual position of the beam limiting component is obtained by averaging x = average (x half i ); Assume that the target position of the beam limiting component is x * , then the x-coordinate difference parameter x * -x.

6. A three-dimensional correction method for a medical linear accelerator beam limiting device according to claim 3, characterized in that: Within the range of the beam limiting device forming the portal image, for each row j, the highlighted area in the column is found, and the centroid coordinate y of the highlighted area is calculated, which is the actual y coordinate position of the beam limiting component. Assuming that the target position of the beam limiting component is y * , then the y coordinate difference is y * -y includes: When the beam limiting component of the beam limiting device is located on the upper side of the portal image, and the beam limiting component moves up and down; Within the upper and lower range of the beam limiting device to form the projection image, for each column j, find the position y with the maximum brightness in the row i , and its brightness I max =max(I(i,j)); By i Look down for brightness The position y half i ; The actual position of the beam limiting component is obtained by averaging y = average (y half i ); Assume that the target position of the constrained component is y * , then the y coordinate difference is y * -y.

7. A three-dimensional correction method for a medical linear accelerator beam limiting device according to claim 3, characterized in that: Within the range of the beam limiting device forming the portal image, for each row j, the highlighted area in the column is found, and the centroid coordinate y of the highlighted area is calculated, which is the actual y coordinate position of the beam limiting component. Assuming that the target position of the beam limiting component is y * , then the y coordinate difference is y * -y includes: When the beam limiting component of the beam limiting device is located at the lower side of the portal image, and the beam limiting component moves up and down; Within the upper and lower range of the beam limiting device to form the projection image, for each column j, find the position y with the maximum brightness in the row i , and its brightness I max = max(I(i, j)); By i Look down for brightness The position y half i ; The actual position of the beam limiting component is obtained by averaging y = average (y half i ); Assume that the target position of the constrained component is y * , then the y coordinate difference is y * -y.

8. A three-dimensional correction method for a medical linear accelerator beam limiting device according to claim 1, characterized in that: The correcting the motion position of the beam limiting device according to the difference information in the motion correction file includes: Obtain the target gantry position and target straightener angle of the medical linear accelerator; According to the target gantry position and the target straightener angle, the corresponding beam limiting component difference parameters are obtained from the difference set {E(g, c, p)} of the beam limiting device position p in the motion correction file; The target operating parameters of the beam limiting component are corrected according to the beam limiting component difference parameters and sent to the motion device to achieve in-place correction of the beam limiting device.

9. A three-dimensional correction system for a medical linear accelerator beam limiting device implementing the three-dimensional correction method according to any one of claims 1 to 8, characterized in that: include: A portal image acquisition module, which acquires portal images generated by a medical linear accelerator; A three-dimensional correction module, which obtains the actual position information of the beam limiting device based on the portal image processing calculation, performs a difference analysis between the actual position information of the beam limiting device and the target position information, and generates a motion correction file; The accelerator control module corrects the motion position of the beam limiting device according to the difference information in the motion correction file.

10. A three-dimensional correction system for a medical linear accelerator beam limiting device according to claim 9, characterized in that: The portal image acquisition module is a two-dimensional flat-panel detector, which is arranged on the frame of the medical linear accelerator and changes its position as the frame rotates. The two-dimensional flat-panel detector is perpendicular to the beam center of the medical linear accelerator and faces the beam direction of the medical linear accelerator.

Images