EPID-based light limiting cylinder position calibration method, apparatus and device, and storage medium

Abstract

The invention discloses a light limiting cylinder position calibration method and device based on EPID, equipment and a storage medium. The method comprises the following steps: acquiring an original calibration image of a light limiting cylinder by using the EPID; according to the isocenter coordinate of the image, intercepting an image in any region range of the isocenter of the original calibration image, and taking the image as a new calibration image for calculating the aperture parameter of the light limiting cylinder; pre-processing the new calibration image; binarizing the preprocessed new calibration image according to the penumbra coefficient; obtaining the boundary contour of the light limiting cylinder according to the new calibration image after binarization, and calculating the aperture parameter of the light limiting cylinder; and calculating the position of the circle center of the light limiting cylinder on the original calibration image based on the aperture parameter of the light limiting cylinder and the size of the area range of the intercepted image, and calibrating the position of the light limiting cylinder. According to the invention, the position of the light limiting cylinder can be identified and calibrated in real time.

Description

Technical Field

[0001] The present invention belongs to the technical field of radiotherapy, and in particular relates to a method, device, equipment and storage medium for calibrating the position of a light-limiting cylinder based on EPID. Background Art

[0002] With the development of radiotherapy technology, intensity modulated radiotherapy has gradually emerged. Intensity modulated radiotherapy requires that the dose distribution in the three-dimensional direction is similar to the shape of the target area, and the radiation dose to the normal tissue around the target area is reduced as much as possible. Therefore, based on this, the capping tube has gradually developed, which can better irradiate the patient's target area and achieve accurate dose distribution.

[0003] The current commonly used method for the light-limiting tube position recognition and detection solution has a relatively complicated process and sometimes needs to be completed with the help of other equipment.

[0004] Traditionally, the isocenter is calculated by holding a lead ball in position on a rod and aligning the center of the lead ball (nominally at the isocenter) with the targeting beam. The lead ball is exposed to film or a digital imager at different combinations of gantry angles and table angles. The center of the ball image is then located by finding the midpoint of the ball image using a ruler.

[0005] Later, an image calculation scheme was proposed on this basis. The image was recorded with an imager and a rectangular coordinate system was established with the isocenter as the origin and converted into a polar coordinate system to calculate the center position of the shot put and the center position of the hole and the deviation respectively.

[0006] However, to place the lead ball at the isocenter, the resolution of the film and digital imager must be very high in order to accurately find the edge of the ball image under magnification. In particular, visual estimation of image edges in conventional film is susceptible to random noise present in the image.

[0007] Some solutions for identifying light-limiting tubes require the use of sensors, which are complex to install and add extra costs, and are time-consuming and labor-intensive. Some solutions also require the use of cameras and calibration plates, which convert the image grayscale and the physical coordinates of the calibration plate to identify the position of the light-limiting tube, and the calculation process is slightly more complicated. Summary of the invention

[0008] In order to solve the above technical problems, the present invention proposes a method, device, equipment and storage medium for calibrating the position of a light-limiting tube based on EPID.

[0009] In order to achieve the above object, the technical solution of the present invention is as follows:

[0010] In a first aspect, the present invention discloses a method for calibrating a position of a light-limiting cylinder based on EPID, comprising:

[0011] Step S1: Use the EPID to collect the original calibration image of the collimator.

[0012] Step S2: According to the image isocenter coordinates, intercept an image of any area range of the isocenter of the original calibration image, and use it as a new calibration image for calculating the collimator aperture parameters.

[0013] Step S3: Preprocess the new calibration image.

[0014] Step S4: Binarize the preprocessed new calibration image according to the penumbra coefficient.

[0015] Step S5: According to the binarized new calibration image, obtain the collimator boundary contour and calculate the collimator aperture parameters.

[0016] The collimator aperture parameters include: the center coordinates of the aperture and the aperture size.

[0017] Step S6: Based on the collimator aperture parameters, combine the size of the intercepted image area range to calculate the position of the collimator center on the original calibration image, and calibrate the collimator position.

[0018] On the basis of the above technical solutions, the following improvements can also be made:

[0019] As a preferred solution, Step S3 includes:

[0020] Step S3.1: Process the new calibration image through mean filtering to remove noise.

[0021] Step S3.2: Obtain the gray histogram of the new calibration image after mean filtering through gray value statistics.

[0022] Step S3.3: Based on the gray histogram, sort in ascending or descending order of gray values,

[0023] Find the gray value that is less than the first threshold and has the largest count, and this gray value is the background value.

[0024] Find the gray value that is greater than the second threshold and has the largest count, and this gray value is the gray value within the radiation field.

[0025] Step S3.4: Remove the background value from the new calibration image after mean filtering to obtain the preprocessed new calibration image.

[0026] As a preferred solution, Step S4 includes the following content:

[0027] Perform binarization processing on each pixel point of the preprocessed new calibration image according to its gray value.

[0028] When the gray value s of any pixel point in the new calibrated image satisfies the following formula, set the gray value of this pixel point to 1, otherwise set it to 0;

[0029] s>(S1 - S2)*α;

[0030] Where: S1 is the gray value within the radiation field;

[0031] S2 is the background value;

[0032] α is the penumbra coefficient.

[0033] As a preferred solution, step S5 includes:

[0034] Step S5.1: Extract the image contour of the binarized new calibrated image to obtain the collimator boundary contour;

[0035] Step S5.2: Draw the extracted collimator boundary contour on a single-channel image with the same size as the original binarized image;

[0036] Step S5.3: Calculate the collimator aperture parameter based on the new image obtained after contour drawing.

[0037] In a second aspect, the present invention discloses a collimator position calibration device based on an EPID, including:

[0038] An image acquisition module, configured to acquire the original calibrated image of the collimator by using an EPID;

[0039] An image cropping module, configured to crop an image within any region range of the isocenter of the original calibrated image according to the image isocenter coordinates, and use it as a new calibrated image for calculating the collimator aperture parameter;

[0040] A preprocessing module, configured to preprocess the new calibrated image;

[0041] A binarization module, configured to binarize the preprocessed new calibrated image according to the penumbra coefficient;

[0042] A parameter calculation module, configured to obtain the collimator boundary contour according to the binarized new calibrated image and calculate the collimator aperture parameter;

[0043] The collimator aperture parameter includes: the center coordinates of the aperture and the aperture size;

[0044] A calibration module, configured to calibrate the collimator position based on the collimator aperture parameter and calculate the position of the collimator center on the original calibrated image in combination with the size of the cropped image region range.

[0045] As a preferred solution, the preprocessing module includes:

[0046] A mean filtering unit, which is used to process the newly calibrated image through mean filtering to remove noise;

[0047] A histogram acquisition unit, which is used to obtain the gray histogram of the newly calibrated image after mean filtering through gray value statistics;

[0048] A gray value acquisition unit, which is used to sort the gray histogram in ascending or descending order based on the gray value,

[0049] find the gray value that is less than the first threshold and has the largest count, and this gray value is the background value;

[0050] find the gray value that is greater than the second threshold and has the largest count, and this gray value is the gray value within the radiation field;

[0051] A preprocessing unit, which is used to remove the background value from the newly calibrated image after mean filtering to obtain the preprocessed newly calibrated image.

[0052] As a preferred solution, the binarization module is used to execute the following method:

[0053] According to the gray value of each pixel point of the preprocessed newly calibrated image, perform binarization processing on it,

[0054] When the gray value s of any pixel point of the newly calibrated image satisfies the following formula, set the gray value of this pixel point to 1, otherwise set it to 0;

[0055] s>(S1 - S2)*α;

[0056] where: S1 is the gray value within the radiation field;

[0057] S2 is the background value;

[0058] α is the penumbra coefficient.

[0059] As a preferred solution, the parameter calculation module includes:

[0060] A contour extraction unit, which is used to extract the image contour of the binarized newly calibrated image to obtain the collimator boundary contour;

[0061] A contour drawing unit, which is used to draw the extracted collimator boundary contour on a single-channel image with the same size as the original binarized image;

[0062] A parameter calculation unit, which is used to calculate the collimator aperture parameter based on the new image obtained after drawing the contour.

[0063] In a third aspect, the present invention discloses a computing device, including:

[0064] One or more processors;

[0065] Memory;

[0066] And one or more programs, where the one or more programs are stored in the memory and configured to be executed by one or more processors, and the one or more programs include instructions for any of the above EPID-based collimator position calibration methods.

[0067] In a fourth aspect, the present invention discloses a storage medium storing one or more computer-readable programs, where the one or more programs include instructions adapted to be loaded and executed by the memory for any of the above EPID-based collimator position calibration methods.

[0068] The present invention discloses an EPID-based collimator position calibration method, device, equipment, and storage medium, which have the following beneficial effects:

[0069] First, the present invention uses an EPID to collect calibration images. The EPID has high resolution and strong stability, with good image accuracy and repeatability. Moreover, compared with films, the contrast of the gray-scale distribution of the peaks and valleys of the EPID images is higher.

[0070] Second, the present invention can directly identify and calibrate the collimator position without relying on other third-party devices, reducing time consumption, labor, and cost, and improving work efficiency.

[0071] Third, the present invention has a high degree of integration and can identify and calibrate the collimator position in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0073] Figure 1 It is a flowchart of the collimator position calibration method provided by the embodiment of the present invention.

[0074] Figure 2 It is a planar structure diagram of the collimator provided by the embodiment of the present invention.

[0075] Figure 3 It is the original calibration image provided by the embodiment of the present invention.

[0076] Figure 4 It is the new calibrated image after cropping provided by the embodiment of the present invention.

[0077] Figure 5 It is the new calibrated image after preprocessing provided by the embodiment of the present invention.

[0078] Figure 6 This is the new calibrated image after binarization provided by the embodiment of the present invention.

[0079] Figure 7 This is the display diagram of the contour boundary of the collimator provided by the embodiment of the present invention.

[0080] Figure 8 This is the original calibrated image showing the center coordinates of the collimator and the isocenter coordinates of the image provided by the embodiment of the present invention.

[0081] Figure 9 is Figure 8 a partial enlarged view of a region in

[0082] Figure 10 This is the block diagram of the collimator position calibration device provided by the embodiment of the present invention.

[0083] Figure 11 This is the block diagram of the computing device provided by the embodiment of the present invention. Detailed implementation manners

[0084] The preferred implementation manners of the present invention will be described in detail below with reference to the accompanying drawings.

[0085] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0086] The expression "including" an element is an "open-ended" expression, which only means that there are corresponding components or steps, and should not be construed as excluding additional components or steps.

[0087] In order to achieve the purpose of the present invention, in some embodiments of the collimator position calibration method based on EPID, the collimator position calibration method includes:

[0088] Step S101: Use EPID to collect the original calibrated image of the collimator;

[0089] Step S102: According to the isocenter coordinates of the image, intercept the image within any region range of the isocenter of the original calibrated image, and use it as the new calibrated image for calculating the aperture parameters of the collimator;

[0090] Step S103: Preprocess the new calibrated image;

[0091] Step S104: Binarize the preprocessed new calibrated image according to the penumbra coefficient.

[0092] Step S105: Obtain the boundary contour of the collimator based on the binarized new calibration image, and calculate the collimator aperture parameters;

[0093] The collimator aperture parameters include: the center coordinates of the aperture and the aperture size;

[0094] Step S106: Based on the collimator aperture parameters, calculate the position of the center of the collimator on the original calibration image in combination with the size of the intercepted image area, and calibrate the position of the collimator.

[0095] Each step is elaborated in detail below.

[0096] In step S101, the original calibration image of the collimator is collected through the EPID image plate on the accelerator, as Figure 3 shown. This process does not require the assistance of other third-party devices.

[0097] After collecting the image, all parameter information required for calculating the collimator aperture parameters can be obtained through image analysis, such as: image isocenter coordinates, image size, pixel value size, etc.

[0098] In step S102, according to the image isocenter coordinates, a region of a certain size (e.g., 289×289) centered on the isocenter of the original calibration image is intercepted, and it is used as the new calibration image for calculating the collimator aperture parameters, as Figure 4 shown.

[0099] Since the collected image may be affected by noise, etc., the obtained image needs to be processed in advance. Step S103 includes:

[0100] Step S103.1: Process the new calibration image through mean filtering to remove noise and smooth the image;

[0101] Step S103.2: Obtain the gray histogram of the new calibration image after mean filtering through gray value statistics;

[0102] Step S103.3: Based on the gray histogram, sort in ascending or descending order of gray values,

[0103] find the gray value that is less than the first threshold and has the largest count, and this gray value is the background value;

[0104] find the gray value that is greater than the second threshold and has the largest count, and this gray value is the gray value within the radiation field;

[0105] Step S103.4: Remove the background value from the new calibration image after mean filtering to obtain the preprocessed new calibration image, as Figure 5 shown.

[0106] The present invention performs grayscale value statistics on the internal and external regions of the radiation field irradiation, and then removes the background value to reduce the influence of noise on the image.

[0107] Specifically, in step 103.3, based on the grayscale histogram, sort the grayscale values from small to large or from large to small, and find the grayscale value with the highest count within a certain range on both the left and right sides of the grayscale histogram. The grayscale value on the left with a smaller value represents the background value, and the grayscale value on the right with a larger value represents the grayscale value within the radiation field.

[0108] Furthermore, step S104 includes the following content:

[0109] Perform binarization processing on each pixel point of the preprocessed new calibrated image according to its grayscale value.

[0110] When the grayscale value s of any pixel point of the new calibrated image satisfies the following formula, set the grayscale value of this pixel point to 1, otherwise set it to 0;

[0111] s>(S1 - S2)*α;

[0112] Where: S1 is the grayscale value within the radiation field;

[0113] S2 is the background value;

[0114] α is the penumbra coefficient.

[0115] For the binarized image, 0 represents black and 1 represents white.

[0116] The present invention introduces the penumbra concept and determines the contour boundary region of the collimator aperture on the image according to the penumbra coefficient. As Figure 6 shown, it is the new calibrated image after binarization.

[0117] Furthermore, step S105 includes:

[0118] Step S105.1: Extract the image contour of the binarized new calibrated image to obtain the collimator boundary contour;

[0119] Step S105.2: Draw the extracted collimator boundary contour on a single-channel image with the same size as the original binarized image that is newly created, as Figure 7 shown;

[0120] Step S105.3: Calculate the collimator aperture parameters based on the new image obtained after contour drawing.

[0121] Step S105 can be calculated based on the opencv image algorithm. Based on the mature and reliable opencv library, the implementation process of the solution is simpler and more convenient.

[0122] Further, in step S106, the position of the center of the aperture of the collimator on the original calibrated image is calculated in combination with the size of the custom cropping range. The difference between the center coordinates of the collimator and the center coordinates of the image is calculated to determine whether the collimator reaches the center position of the image. If not, the collimator can be guided to move a certain distance towards the center position of the image according to the calculation result until it reaches the center position of the image.

[0123] The present invention has a high degree of integration and can perform calculations in real time. After collecting images through the imaging plate on the accelerator, the position recognition and calibration of the collimator can be directly carried out on the other side. If the predetermined center position is not reached, the collimator can be accurately guided to move according to the calculation result.

[0124] As Figure 8 and 9 shown in a specific embodiment, the orange line represents the boundary contour of the collimator, and the cross represents the center of the circle. The green cross represents the center of the image.

[0125] In some other embodiments, as Figure 10 shown, the present invention discloses a collimator position calibration device based on EPID, including:

[0126] An image acquisition module 201, configured to acquire the original calibrated image of the collimator by using EPID;

[0127] An image cropping module 202, configured to crop an image of any area range centered on the image according to the center coordinates of the image, and use it as a new calibrated image for calculating the aperture parameters of the collimator;

[0128] A preprocessing module 203, configured to preprocess the new calibrated image;

[0129] A binarization module 204, configured to binarize the preprocessed new calibrated image according to the penumbra coefficient;

[0130] A parameter calculation module 205, configured to obtain the boundary contour of the collimator according to the binarized new calibrated image, and calculate the aperture parameters of the collimator;

[0131] The aperture parameters of the collimator include: the center coordinates of the aperture and the aperture size;

[0132] A calibration module 206, configured to calibrate the position of the collimator based on the aperture parameters of the collimator and calculate the position of the center of the collimator on the original calibrated image in combination with the size of the cropped image area.

[0133] Further, the preprocessing module includes:

[0134] An average filtering unit, configured to process the new calibrated image through average filtering to remove noise;

[0135] A histogram acquisition unit for obtaining the grayscale histogram of the newly calibrated image after mean filtering through grayscale value statistics;

[0136] A grayscale value acquisition unit for sorting based on the grayscale histogram in ascending or descending order of grayscale values,

[0137] finding the grayscale value that is less than the first threshold and has the largest count, and this grayscale value is the background value;

[0138] finding the grayscale value that is greater than the second threshold and has the largest count, and this grayscale value is the grayscale value within the radiation field;

[0139] A preprocessing unit for removing the background value from the newly calibrated image after mean filtering to obtain the preprocessed newly calibrated image.

[0140] Furthermore, the binarization module is used to execute the following method:

[0141] Performing binarization processing on each pixel point of the preprocessed newly calibrated image according to its grayscale value,

[0142] When the grayscale value s of any pixel point in the newly calibrated image satisfies the following formula, set the grayscale value of this pixel point to 1, otherwise set it to 0;

[0143] s>(S1 - S2)*α;

[0144] where: S1 is the grayscale value within the radiation field;

[0145] S2 is the background value;

[0146] α is the penumbra coefficient.

[0147] Furthermore, the parameter calculation module includes:

[0148] A contour extraction unit for extracting the image contour of the binarized newly calibrated image to obtain the boundary contour of the collimator;

[0149] A contour drawing unit for drawing the extracted boundary contour of the collimator on a single-channel image with the same size as the original binarized image;

[0150] A parameter calculation unit for calculating the aperture parameter of the collimator based on the new image obtained after drawing the contour.

[0151] Furthermore, it should be noted that when calibrating the position of the light-limiting cylinder by the light-limiting cylinder position calibration device provided in the above embodiments, only the division of the above functional modules is used for illustration. In practical applications, the above functions can be allocated to different functional modules according to needs, that is, the internal structure of the light-limiting cylinder position calibration device is divided into different functional modules to complete all or part of the functions described above.

[0152] In addition, the light-limiting cylinder position calibration device provided in the above embodiments and the embodiments of the light-limiting cylinder position calibration method belong to the same concept. For the specific implementation process, please refer to the method embodiments and will not be elaborated here.

[0153] In addition, in some other embodiments, as Figure 11 shown, the present invention also discloses a computing device, including:

[0154] One or more processors 301;

[0155] A memory 302;

[0156] And one or more programs, where one or more programs are stored in the memory 302 and are configured to be executed by one or more processors 301. The one or more programs include instructions for the light-limiting cylinder position calibration method disclosed in the above embodiments.

[0157] The processor 301 may include one or more processing cores, such as: a 4-core processor, an 8-core processor, etc. The processor 301 may be implemented in at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). The processor 301 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the wake state, also known as the CPU (Central Processing Unit); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 301 may be integrated with a GPU (Graphics Processing Unit), and the GPU is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 301 may further include an AI (Artificial Intelligence) processor, and the AI processor is used to process computational operations related to machine learning.

[0158] The memory 302 may include one or more computer-readable storage media, which may be non-transitory. The memory 302 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices and flash storage devices. In some embodiments, the non-transitory computer-readable storage media in the memory 302 is used to store at least one instruction for being executed by the processor 301 to implement the light-limiting cylinder position calibration method provided in the method embodiments of the present invention.

[0159] In addition, the computing device may optionally further include: a peripheral device interface and at least one peripheral device. The processor 301, the memory 302 and the peripheral device interface may be connected through a bus or signal lines. Each peripheral device may be connected to the peripheral device interface through a bus, signal lines or a circuit board. Schematically, the peripheral devices include but are not limited to: radio frequency circuits, touch display screens, audio circuits, and power supplies, etc.

[0160] Of course, the computing device may also include fewer or more components, and this embodiment does not limit this.

[0161] In addition, in some other embodiments, the present invention also discloses a storage medium storing one or more computer-readable programs, and the one or more programs include instructions adapted to be loaded and executed by the memory to perform the light-limiting cylinder position calibration method disclosed in the above embodiments.

[0162] The present invention discloses a light-limiting cylinder position calibration method, device, equipment and storage medium based on EPID, which has the following beneficial effects:

[0163] First, the present invention uses EPID to collect calibration images. EPID has high resolution and strong stability, with good image accuracy and repeatability. Moreover, compared with films, the contrast of the peak-valley gray distribution of EPID images is higher.

[0164] Second, the present invention can directly identify and calibrate the position of the light-limiting cylinder without relying on other third-party devices, reducing time consumption, labor and cost, and improving work efficiency.

[0165] Third, the present invention has a high degree of integration and can identify and calibrate the position of the light-limiting cylinder in real time.

[0166] The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only used to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and all these changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. The method for calibrating the position of the light-limiting cylinder based on EPID is characterized in that: include: Step S1: using EPID to collect the original calibration image of the light-limiting tube; Step S2: According to the image isocenter coordinates, an image of any area within the isocenter of the original calibration image is captured, and the image is used as a new calibration image for calculating the aperture parameters of the light-limiting tube; Step S3: preprocessing the new calibration image; Step S4: binarize the preprocessed new calibration image according to the penumbra coefficient; Step S5: according to the binarized new calibration image, obtain the boundary contour of the light-limiting cylinder and calculate the aperture parameters of the light-limiting cylinder; The aperture parameters of the light-limiting tube include: the coordinates of the center of the aperture and the size of the aperture; Step S6: Based on the aperture parameters of the light-limiting tube and in combination with the size of the intercepted image area, the position of the center of the light-limiting tube on the original calibration image is calculated, and the position of the light-limiting tube is calibrated.

2. The method for calibrating the position of the light-limiting cylinder according to claim 1, characterized in that: The step S3 comprises: Step S3.1: Process the new calibration image by mean filtering to remove noise; Step S3.2: Obtain the grayscale histogram of the newly calibrated image after mean filtering through grayscale value statistics; Step S3.3: Based on the grayscale histogram, sort the grayscale values ​​from small to large or from large to small. Find the grayscale value with the largest count and a grayscale value less than the first threshold, which is the background value; Find the grayscale value with a grayscale value greater than the second threshold and the largest number of counts, and this grayscale value is the grayscale value in the field; Step S3.4: remove the background value from the new calibration image after mean filtering to obtain a preprocessed new calibration image.

3. The method for calibrating the position of the light-limiting cylinder according to claim 2, characterized in that: The step S4 includes the following contents: According to the gray value of each pixel of the preprocessed new calibration image, it is binarized. When the grayscale value s of any pixel of the newly calibrated image satisfies the following formula, the grayscale value of the pixel is set to 1, otherwise it is set to 0; s>(S1-S2)*α; Where: S1 is the gray value in the field; S2 is the background value; α is the penumbra coefficient.

4. The method for calibrating the position of the light-limiting cylinder according to claim 1, characterized in that: The step S5 comprises: Step S5.1: extracting the image contour of the binarized new calibration image to obtain the boundary contour of the light-limiting tube; Step S5.2: Draw the extracted light-limiting tube boundary contour on the newly created single-channel image of the size of the original binary image; Step S5.3: Based on the new image obtained after drawing the outline, the aperture parameters of the light-limiting tube are calculated.

5. The light-limiting tube position calibration device based on EPID is characterized by: include: An image acquisition module is used to acquire the original calibration image of the light-limiting tube using EPID; An image capture module is used to capture an image of any area within the isocenter of the original calibration image according to the isocenter coordinates of the image, and use it as a new calibration image for calculating the aperture parameters of the light-limiting tube; A preprocessing module, used for preprocessing the new calibration image; A binarization module is used to binarize the pre-processed new calibration image according to the penumbra coefficient; A parameter calculation module is used to obtain the boundary contour of the light-limiting tube and calculate the aperture parameters of the light-limiting tube according to the binarized new calibration image; The aperture parameters of the light-limiting tube include: the coordinates of the center of the aperture and the size of the aperture; The calibration module is used to calculate the position of the center of the light limiting cylinder on the original calibration image based on the aperture parameters of the light limiting cylinder and the size of the intercepted image area, and calibrate the position of the light limiting cylinder.

6. The light-limiting cylinder position calibration device according to claim 5, characterized in that: The preprocessing module comprises: A mean filter unit, used to process the new calibration image through mean filtering to remove noise; A histogram acquisition unit, used to obtain a grayscale histogram of a newly calibrated image after mean filtering by grayscale value statistics; The gray value acquisition unit is used to sort the gray values ​​from small to large or from large to small based on the gray histogram. Find the grayscale value with the largest count and a grayscale value less than the first threshold, which is the background value; Find the grayscale value with a grayscale value greater than the second threshold and the largest number of counts, and this grayscale value is the grayscale value in the field; The preprocessing unit is used to remove the background value of the new calibration image after the mean filtering to obtain the preprocessed new calibration image.

7. The light-limiting cylinder position calibration device according to claim 6, characterized in that: The binarization module is used to perform the following method: According to the gray value of each pixel of the preprocessed new calibration image, it is binarized. When the grayscale value s of any pixel of the newly calibrated image satisfies the following formula, the grayscale value of the pixel is set to 1, otherwise it is set to 0; s>(S1-S2)*α; Where: S1 is the gray value in the field; S2 is the background value; α is the penumbra coefficient.

8. The light-limiting cylinder position calibration device according to claim 5, characterized in that: The parameter calculation module comprises: A contour extraction unit is used to extract the image contour of the binarized new calibration image to obtain the boundary contour of the light-limiting tube; A contour drawing unit, used for drawing the extracted light-limiting tube boundary contour on a newly created single-channel image of the size of the original binary image; The parameter calculation unit is used to calculate the aperture parameters of the light-limiting tube based on the new image obtained after drawing the outline.

9. A computing device, characterized in that include: one or more processors; Memory; And one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by one or more processors, and one or more of the programs include instructions for the EPID-based light-limiting tube position calibration method described in any one of claims 1-4 above.

10. A storage medium, characterized in that The storage medium stores one or more computer-readable programs, and the one or more programs include instructions, and the instructions are suitable for being loaded by the memory and executing the EPID-based light-limiting tube position calibration method described in any one of claims 1-4.

Images