A three-dimensional correction method and system for a medical linear accelerator beam limiting device

Abstract

The present invention discloses a three-dimensional correction method and system for a beam limiting device of a medical linear accelerator, wherein the three-dimensional correction method includes: acquiring a portal image generated by a medical linear accelerator; obtaining actual position information of the beam limiting device based on processing and calculation of the portal image, performing difference analysis between the actual position information of the beam limiting device and the target position information, and generating a motion correction file; and correcting the motion position of the beam limiting device based on the difference information in the motion correction file. The present invention acquires a portal image generated by a medical linear accelerator, processes and analyzes the portal 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, thereby realizing automatic correction of the beam limiting device and improving the accuracy of the motion of the beam limiting device.

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, to improve the therapeutic efficiency of medical linear accelerators, beam limiting devices (gratings and tungsten gates) are often used to adjust the radiation's range and shape, optimize dose distribution, and ensure that the radiation reaches only the area requiring treatment, reducing leakage dose to normal tissues to meet the treatment needs of different patients and tumors. Therefore, the accuracy of the beam limiting device is crucial to the precision and effectiveness 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. By observing the consistency of the field shape and size with the plan, as well as the uniformity of the dose distribution, the positioning accuracy of the beam limiting device is evaluated.

[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 the efficiency of use.

[0009] Problems and defects of the second method: (1) The film analysis method requires multiple steps such as 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, which 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 the medical linear accelerator causes the shape and size of the rays to be inaccurate with the actual ones under different racks and collimator angles due to assembly problems, and there is deviation in the positioning accuracy of the grating and tungsten gate. 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 beam limiting device of a medical linear accelerator. 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] The actual position information of the beam limiting device is obtained by calculation based on the portal image processing, and the 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, including:

[0018] The radiation field images of the medical linear accelerator at different gantry angles g and collimator angles c were 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 or collimator angle of the medical linear accelerator, a calculation process for 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 projection 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. Assuming 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. Assuming 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 * The difference between -y and y coordinates is y * -y form 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, 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:

[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 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, 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;

[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 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 include:

[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 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 beam limiting 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 include:

[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 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 beam limiting 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 collimator angle of the medical linear accelerator;

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

[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] Port field image acquisition module, which collects the port field images generated by the medical linear accelerator;

[0053] a three-dimensional correction module, which obtains actual position information of the beam limiting device based on the portal image processing calculation, performs 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 present invention provides a three-dimensional correction method for a medical linear accelerator beam-limiting device, primarily addressing issues such as inaccurate positioning of gratings and tungsten gates in the beam-limiting device at different rack and collimator angles, resulting from assembly, and errors in the displayed beam position. The present invention collects a portal image generated by the medical linear accelerator, processes and analyzes the portal image to determine the deviation between the actual and target position information of the beam-limiting device, and generates a correction file. The control system of the medical linear accelerator receives and analyzes the correction file, achieving automatic correction of the beam-limiting device and improving the accuracy of the beam-limiting device's movement.

[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 limiter. The three-dimensional correction method of the medical linear accelerator beam limiter of this embodiment can perform difference analysis and correction on the position of the beam limiter.

[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 error caused by the process. A three-dimensional correction method for 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 Flowchart of a three-dimensional calibration method for a medical linear accelerator beam limiting device according to an embodiment of the present invention Figure 1 ;

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

[0063] Figure 3 System diagram of a three-dimensional correction system for a medical linear accelerator beam limiting device 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 solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to 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 claimed invention, but merely represents some embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall 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 therein 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, it does not require further definition or explanation in subsequent drawings.

[0069] In the description of the present invention, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is typically placed when in use, or the orientations or positional relationships commonly understood by those skilled in the art. Such terms are intended solely to facilitate the description of the present invention and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" and the like are used solely for distinction and should not be construed 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] The actual position information of the beam limiting device is obtained by calculation based on the portal image processing, and the 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] This embodiment of a three-dimensional calibration method for a medical linear accelerator beam limiter primarily addresses the issue of inaccurate positioning of the grating and tungsten gates in the beam limiter at different gantry and collimator angles, resulting in errors in the displayed beam position. This method captures a portal image generated by the medical linear accelerator, processes and analyzes the image to determine the deviation between the beam limiter's actual and target positions, and generates a calibration file. The calibration file is then received and analyzed by the control system of the medical linear accelerator to automatically calibrate the beam limiter and improve its motion accuracy.

[0075] Compared with existing technologies, the three-dimensional correction method for 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 limiter. The three-dimensional correction method of the medical linear accelerator beam limiter of this embodiment can perform difference analysis and correction on the position of the beam limiter.

[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 error caused by the process. A three-dimensional correction method for 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 medical linear accelerator beam limiter of this embodiment, the actual position information of the beam limiter is obtained based on the portal image processing calculation, and the difference analysis between the actual position information of the beam limiter and the target position information is performed to generate a motion correction file, including:

[0079] The radiation field images of the medical linear accelerator at different gantry angles g and collimator angles c were 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] This embodiment acquires images of the beam field at different gantry angles g and collimator angles c of the medical linear accelerator to obtain a difference set {E(g, c, p)} of the beam limiter position p. Thus, during the actual operation of the medical linear accelerator, after the target gantry angle g and target collimator angle c of the medical linear accelerator are determined, corresponding difference parameters E(g, c, p) can be obtained based on the difference set {E(g, c, p)} of the beam limiter position p. The medical linear accelerator can perform motion correction of the beam limiter based on the difference parameters E(g, c, p), eliminating the need to use dedicated image processing software to analyze the position of the beam limiter, thereby improving work efficiency and reducing 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 or collimator angle of the medical linear accelerator, a calculation process for 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 projection 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. Assuming 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. Assuming 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 form 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. This is based on the correspondence between image brightness and X-ray energy distribution in X-ray equipment in medical imaging equipment, 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 highlighted 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 this distribution, and is calculated as follows:

[0089] For an image matrix, each pixel has a position (x, y) and a corresponding brightness value I(x, y). A pixel with a higher brightness value means that the pixel at that position is more affected by the rays, and the brightness value is positively correlated with the ray energy distribution.

[0090] The formula for calculating the center of mass is:

[0091] xcenter=∑(x·I(x,y)) / ∑I(x,y)

[0092] ycenter=∑(y·I(x,y)) / ∑I(x,y)

[0093] Here, I(x,y) is the brightness value of each pixel in the image, and x and y are the coordinates of that pixel. This formula indicates that pixels with higher brightness values ​​have a greater influence on the accuracy of obtaining the coordinates and mass (or weight) of each point in the image, which can be used to calculate the center of mass position, i.e., the weighted average of the brightness.

[0094] This calculation doesn't rely 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 are accurately obtained, the center of mass position can be calculated. This method is highly robust, and changes in the image shape (such as rotation, scaling, and deformation) will not significantly affect the calculated position. Furthermore, the graphic object or image region can be treated as a single point (i.e., the center of mass), which greatly simplifies the problem.

[0095] Specifically, in a three-dimensional correction method for a medical linear accelerator beam limiting device of this embodiment, 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:

[0096] When the beam limiting component of the beam limiting device (such as the tungsten block on the left side 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 ranges of the beam-limiting device forming the projection image, for each row i (for grating blades, the number of rows is small, possibly only a few rows; for tungsten gate components, the number of rows may be up to 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 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 medical linear accelerator beam limiting device of this embodiment, 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:

[0102] When the beam limiting component of the beam limiting device (such as the tungsten block on the right side of the tungsten gate) is located on the right side of the radiation field 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 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 the 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 include:

[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 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 beam limiting component is y * , then the y-coordinate difference is y * -y.

[0113] In the three-dimensional correction method of the 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 tungsten block on the right side of the tungsten gate) is located on 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 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 beam limiting 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 medical linear accelerator beam limiter of this embodiment, the correction of the motion position of the beam limiter according to the difference information in the motion correction file includes:

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

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

[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 a calibration file, obtains the difference between the moving target gantry position, collimator angle, and beam limiter position of the beam limiter component, compensates the moving target based on the difference and sends it to the motion device, controls the motion of the beam limiter device, achieves in-place correction of the grating and tungsten gate positions under different gantry and collimator angles, and drives the beam limiter device 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] Port field image acquisition module, which collects the port field images generated by the medical linear accelerator;

[0125] a three-dimensional correction module, which obtains actual position information of the beam limiting device based on the portal image processing calculation, performs 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. 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 tungsten threshold beam device.

[0129] The three-dimensional correction module is used to receive instructions from the accelerator control module. Once the tungsten gate and grating inspection item instructions are received from the accelerator control module, it starts to collect the portal 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 the difference parameters, generates a correction file, and feeds the correction file back to the accelerator control module through the network.

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

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

[0133] The 3D calibration module, consisting of 3D Calibration Software (3DCS) and a computer installed with the software, is used to control the EPID to acquire portal images and calculate the position of the beam limiter based on the images to generate a calibration file.

[0134] The accelerator control module, which consists of the accelerator control software (LinacControlSoftware, LCS) and the computer on which the software is installed, is used to control the movement and beam output of the beam limiting device, and to receive the correction file sent by the 3D 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 gantry of the medical linear accelerator. Its position changes as the gantry 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. It is used to collect the radiation field image formed by the radiation 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 baseband or as part of a carrier wave, which carries a readable program code. This propagated data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, 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 conjunction with an instruction execution system, device, or component. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the above.

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

[0139] The electronic device is implemented as a general-purpose computing device. The processor may be one or multiple processors operating in concert. The present invention also does not exclude distributed processing, meaning the processors may be dispersed across 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, typically a machine-readable code, which can be executed by the processor to enable the electronic device to perform the method of the present invention, or at least some 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 devices 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 screens, and some electronic devices also include human-computer interaction elements such as buttons and keyboards. As long as the electronic device can execute a computer-readable program stored in its memory to implement the method of the present invention or at least some of the steps of the method, it can be considered 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 USB flash drive, a mobile hard disk, etc.), or it can be distributed and stored on a network, as long as it enables an 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 this specification has described the present invention 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, wherein the beam limiting device includes a grating and a tungsten gate, characterized in that: include: Collect the portal images produced by medical linear accelerator; The actual position information of the beam limiting device is obtained by calculation based on the portal image processing, and the 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; Correct the motion position of the beam limiting device according to the difference information in the motion correction file; The actual position information of the beam limiting device is obtained by calculation based on the portal image processing, and the 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, which includes: The radiation field images of the medical linear accelerator at different gantry angles g and collimator angles c were collected respectively; Calculating a difference set {E(g, c, p)} of the beam limiting device position p based on each of the portal images; For any gantry angle or collimator angle of a medical linear accelerator, the calculation process for 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 projection 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. Assuming 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 column 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. Assuming that the target position of the beam limiting component is y * , then the y-coordinate difference is y * -y; The x-coordinate difference parameter x * -The difference between x and y coordinates is y * -y form 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.

2. A three-dimensional correction method for a medical linear accelerator beam limiting device according to claim 1, 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 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.

3. The three-dimensional correction method of a medical linear accelerator beam limiting device according to claim 1, 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 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.

4. The three-dimensional correction method of a medical linear accelerator beam limiting device according to claim 1, characterized in that: Within the range of the beam limiting device forming the portal image, for each column 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 include: 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 column i , and its brightness I max =max(I(i, j)); By y i Look down for brightness 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 beam limiting component is y * , then the y-coordinate difference is y * -y.

5. The three-dimensional correction method of a medical linear accelerator beam limiting device according to claim 1, characterized in that: Within the range of the beam limiting device forming the portal image, for each column 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 include: 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 column i , and its brightness I max =max(I(i,j)); By y i Look down for brightness 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 beam limiting component is y * , then the y-coordinate difference is y * -y.

6. The three-dimensional correction method of 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 collimator angle of the medical linear accelerator; Obtaining corresponding beam limiting component difference parameters from the difference set {E(g,c,p)} of the beam limiting device position p in the motion correction file according to the target gantry position and the target straightener angle; 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.

7. 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 6, characterized in that: include: Port field image acquisition module, which collects the port field images generated by the medical linear accelerator; a three-dimensional correction module, which obtains actual position information of the beam limiting device based on the portal image processing calculation, performs 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.

8. The three-dimensional correction system for a medical linear accelerator beam limiting device according to claim 7, 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