A radiation source position verification method based on grayscale features

Abstract

The present invention discloses a method for verifying the position of a radiation source based on grayscale features. This method belongs to the fields of nuclear energy and nuclear technology applications, such as radiotherapy and industrial nondestructive testing. The specific steps are: obtaining a series of contour point coordinates from the radiation source to a detection device based on the coordinates of the radiation source contour points, the distance between the radiation source and the isocenter, and the distance between the radiation source and the detection device; when the radiation source radiates, measuring the radiation field passing through the irradiated phantom using an installed detection device to obtain a transmitted radiation field distribution; performing noise reduction processing on the measured transmitted radiation field distribution to obtain a noise-reduced transmitted radiation field distribution; processing the noise-reduced transmitted radiation field distribution to obtain the radiation field contour point information, comparing it with the contour point coordinates to obtain the radiation source position offset parameter. The present invention can efficiently and accurately verify the position of the radiation source, thereby effectively ensuring the accurate implementation of radiation.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear energy and nuclear technology applications such as radiotherapy and industrial non-destructive testing, and relates to a method for verifying the position of a radiation source based on grayscale features. Background Art

[0002] Radiation sources emit radiation that can irradiate materials, enabling radiotherapy, nondestructive monitoring, and radiation processing. The accuracy of the radiation source's position significantly impacts its effectiveness. When the source's position shifts, the spatial distribution of the emitted radiation also shifts, leading to deviations in the planned radiation dose and the reconstructed images. Large deviations can lead to serious accidents. Therefore, research on radiation source position verification methods is needed to ensure that the source's position is within the planned range, effectively ensuring accurate radiation delivery.

[0003] Currently, radiation source position calibration generally uses a pre-verification method, that is, the radiation source position is verified before irradiation. However, since the radiation source position can change in many applications, verifying whether the changed radiation source reaches the planned position can also affect the accurate implementation of radiation. Therefore, it is necessary to develop a method that can verify the radiation source position in advance or online. Summary of the Invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a method for verifying the position of a radiation source based on grayscale features.

[0005] Technical solution: The present invention provides a method for verifying the location of a radiation source based on grayscale features. The specific steps are as follows:

[0006] (1.1), according to the coordinates of the radiation source contour point (x i ,y i ), the distance information SAD between the radiation source and the isocenter, the distance information SID between the radiation source and the detection device, and the coordinates of the contour points on the radiation source and the detection device. Where i = 1, 2, ... 2N, 2N represents the number of contour points,

[0007] (1.2) When the radiation source radiates, the radiation field passing through the irradiated phantom is measured by the installed detection device to obtain the transmitted radiation field distribution;

[0008] (1.3) performing noise reduction processing on the measured transmitted radiation field distribution to obtain the noise-reduced transmitted radiation field distribution Gray(x,y);

[0009] (1.4) Process the obtained transmitted radiation field distribution Gray (x, y) after noise reduction to obtain the coordinates of the radiation field contour points, and compare them with the contour point coordinates obtained in step (1.1) By comparison, the radiation source position offset parameters are finally obtained.

[0010] Furthermore, in step (1.2), the detection device includes a two-dimensional flat panel detector and a detector array.

[0011] Furthermore, in the step (1.4), the obtained radiation field contour point coordinates and the obtained contour point coordinates are compared. The specific steps for comparing and finally obtaining the radiation source position offset parameters are as follows:

[0012] (1.4.1) Take the grayscale value of the line segment passing through the geometric center point along the y direction and calculate its corresponding gradient value

[0013] (1.4.2), from top to bottom, the corresponding gradient value Perform point-by-point evaluation and record the corresponding gradient value Maximum position Y top,i and minimum position Y down,i , calculate the Y direction offset of the radiation source Use Δy to adjust the contour point parameters Make corrections and get

[0014] (1.4.3), according to the maximum open field size of the radiation source (x length ,y length ), draw the radiation source projection area in the transmitted radiation field distribution after noise reduction

[0015] in, represents the expansion factor, D x 、D y They represent the maximum value of the effective detection area of ​​the detection device in the X / Y direction, and min represents the minimum value;

[0016] (1.4.4), take along the x direction Grayscale values ​​of series line segments and calculate their corresponding gradient values

[0017] Where i = 1, 2, ... N; N represents half of the number of contour points;

[0018] (1.4.5), from left to right Conduct point-by-point assessment and record Maximum value position and minimum position Thus, the coordinate series of the contour points of the collected image is obtained:

[0019]

[0020] (1.4.6) By comparing the contour point coordinates of the collected image and the contour coordinates of the radiation source to the detection device The offset parameters of each contour point coordinate are obtained, thereby obtaining the radiation source position offset coefficient and verifying the position of the radiation source.

[0021] Beneficial effects: Compared with the prior art, the radiation source position verification method of the present invention obtains the radiation source position deviation based on the actual irradiation grayscale image characteristics, so that the radiation source position can be dynamically verified in advance and during implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is an operational flow chart of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] like Figure 1 The method for verifying the position of a radiation source based on grayscale features of the present invention comprises the following steps:

[0025] 1) According to the coordinates of the radiation source contour point (x i ,y i ), the distance information SAD between the radiation source and the isocenter, the distance information SID between the radiation source and the detection device, and the coordinates of the contour points on the radiation source and the detection device. Where i=1,2,…2N, 2N is the number of contour points,

[0026] 2) When the radiation source radiates, the radiation field passing through the irradiated phantom is measured by the installed detection device to obtain the transmitted radiation field distribution, wherein the detection device includes a two-dimensional flat panel detector and a detector array;

[0027] 3) Performing noise reduction processing on the measured transmitted radiation field distribution to obtain the noise-reduced transmitted radiation field distribution Gray(x,y);

[0028] 4) Process the transmitted radiation field distribution Gray (x, y) after noise reduction obtained in step 3) to obtain the coordinates of the radiation field contour points, and compare them with the coordinates of the contour points obtained in step 1) By comparison, the radiation source position offset parameters are obtained.

[0029] The radiation source position verification method of the present invention obtains the radiation source position deviation based on the actual irradiation grayscale image characteristics, so that the radiation source position can be dynamically verified in advance and during implementation.

[0030] In the above step 4), the specific steps are as follows:

[0031] (4.1) Take the grayscale value of the line segment passing through the geometric center point along the y direction and calculate its corresponding gradient value

[0032] (4.2), the corresponding gradient values ​​from top to bottom Perform point-by-point evaluation and record the corresponding gradient value Maximum position Y top，i and minimum position Y down,i , calculate the Y direction offset of the radiation source Use Δy to adjust the contour point parameters Make corrections and get

[0033] (4.3), according to the maximum open field size of the radiation source (x length ,y length ), draw the radiation source projection area in the transmitted radiation field distribution after noise reduction

[0034] in, represents the expansion factor, D x 、D y They represent the maximum value of the effective detection area of ​​the detection device in the X / Y direction, and min represents the minimum value;

[0035] (4.4), along the x direction Grayscale values ​​of series line segments and calculate their corresponding gradient values

[0036] Where i = 1, 2, .. N, N represents half of the number of contour points;

[0037] (4.5), from left to right Conduct point-by-point assessment and record Maximum value position and minimum position Thus, the coordinate series of the contour points of the collected image is obtained:

[0038]

[0039] (4.6) By comparing the contour point coordinates of the collected image and the contour coordinates of the radiation source to the detection device The offset parameters of each contour point coordinate are obtained, thereby obtaining the radiation source position offset coefficient and verifying the position of the radiation source.

[0040] Example:

[0041] The online position verification of the radiation source of a radiotherapy system is performed. During treatment, the radiation source field size is 10 cm × 8 cm, the source wheelbase is 100 cm, the two-dimensional measurement device size is 41 cm × 41 cm, the resolution is 512 × 512, and the source distance is 160 cm. The corresponding source contour point coordinates are (-5, -4), (-5, 4), (5, 4), (5, -4). The specific steps are as follows:

[0042] 1. Obtain the coordinates of the radiation source contour points on the two-dimensional measurement device:

[0043] According to the coordinates of the contour points of the radiation source, the source wheelbase, and the distance between the two-dimensional measuring device and the source, the coordinates of the contour points on the two-dimensional measuring device can be calculated as (-8, -6.4), (-8, 6.4), (8, 6.4), (8, -6.4);

[0044] 2. Radiation dose measurement:

[0045] Turn on the radiation source to irradiate the radiation phantom medium, and at the same time turn on the two-dimensional measurement device to receive the transmitted radiation, form the transmitted radiation field distribution, and generate the corresponding grayscale image;

[0046] 3. Transmitted radiation field distribution noise reduction processing:

[0047] The Gaussian smoothing method is used to perform noise reduction on the measured transmitted radiation field distribution to obtain the noise-reduced transmitted radiation field distribution Gray(x,y);

[0048] 4. Calculation of radiation source position offset:

[0049] (1) Take the grayscale value of the line segment passing through the geometric center point along the y direction and calculate its corresponding gradient value

[0050] (2) The corresponding gradient values ​​from top to bottom Perform point-by-point evaluation and record the corresponding gradient value Maximum position Y top,i and minimum position Y down,i , calculate the Y direction offset of the radiation source Use Δy to adjust the contour point parameters Make corrections and get

[0051] (3) According to the maximum open field size of the radiation source (10, 8), the radiation source projection area (19.2, 15.36) is drawn in the transmitted radiation field distribution after noise reduction, and the expansion factor is 0.2;

[0052] (4) Take along the x direction Grayscale values ​​of series line segments and calculate their corresponding gradient values Where i = 1, 2;

[0053] (5) From left to right Conduct point-by-point assessment and record Maximum value position and minimum position Thus, the coordinate series of the contour points of the collected image is obtained:

[0054]

[0055] (6) By comparing the contour point coordinates of the collected image and the contour coordinates of the radiation source to the detection device The offset parameters of each contour point coordinate are obtained, thereby obtaining the radiation source position offset coefficient and verifying the position of the radiation source.

[0056] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A radiation source position verification method based on grayscale features, characterized in that: The specific steps are as follows: (1.1), according to the coordinates of the radiation source contour point (x i ,y i ), the distance information SAD between the radiation source and the isocenter, the distance information SID between the radiation source and the detection device, and the coordinates of the contour points on the radiation source and the detection device. Where i = 1, 2, ... 2N, 2N represents the number of contour points, (1.2) When the radiation source radiates, the radiation field passing through the irradiated phantom is measured by the installed detection device to obtain the transmitted radiation field distribution; (1.3) performing noise reduction processing on the measured transmitted radiation field distribution to obtain the noise-reduced transmitted radiation field distribution Gray(x,y); (1.4) Process the obtained transmitted radiation field distribution Gray (x, y) after noise reduction to obtain the coordinates of the radiation field contour points, and compare them with the contour point coordinates obtained in step (1.1) By comparison, the radiation source position offset parameters are finally obtained; The specific steps are as follows: (1.4.1) Take the grayscale value of the line segment passing through the geometric center point along the y direction and calculate its corresponding gradient value (1.4.2), from top to bottom, the corresponding gradient value Perform point-by-point evaluation and record the corresponding gradient value Maximum position Y top,i and minimum position Y down,i , calculate the Y direction offset of the radiation source Use Δy to compare the coordinates of the contour points Make corrections and get (1.4.3), according to the maximum open field size of the radiation source (x length ,y length ), draw the radiation source projection area in the transmitted radiation field distribution after noise reduction Where, represents the expansion factor, D x 、D y They represent the maximum value of the effective detection area of ​​the detection device in the X / Y direction, and min represents the minimum value; (1.4.4), take along the x direction Grayscale values ​​of series line segments and calculate their corresponding gradient values Where i = 1, 2, ... N; N represents half of the number of contour points; (1.4.5), from left to right Conduct point-by-point assessment and record Maximum value position and minimum position Thus, the coordinate series of the contour points of the collected image is obtained: (1.4.6) By comparing the coordinates of the contour points in the collected image with the coordinates of the contour points on the radiation source to the detection device The offset parameters of each contour point coordinate are obtained, thereby obtaining the offset parameters of the radiation source position and verifying the position of the radiation source.

2. The method for verifying the position of a radiation source based on grayscale features according to claim 1, wherein: In step (1.2), the detection device includes a two-dimensional flat panel detector and a detector array.

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