Neutron radiography method and system

Abstract

The application provides a neutron radiography method and system. The neutron radiography method comprises obtaining a to-be-corrected image obtained by neutron radiography and a neutron fluence rate during the neutron radiography, wherein the to-be-corrected image is at least two, and the neutron fluence rate corresponds to the to-be-corrected image one by one; and the to-be-corrected image is normalized according to the neutron fluence rate. The neutron radiography system comprises a neutron source, an image acquisition device and at least one fluence rate measuring instrument. The neutron source is configured to release a neutron beam in a beam space; the image acquisition device is configured to acquire neutrons and generate a to-be-corrected image; and the fluence rate measuring instrument is arranged between the neutron source and the image acquisition device and is used for measuring the neutron fluence rate of the neutron beam. The neutron radiography method and system provided by the application can reduce the problem of image data distortion caused by the fluctuation of the neutron source intensity by obtaining the neutron fluence rate and performing normalization correction on the to-be-corrected image, thereby improving the image quality of the neutron radiography.

Description

Technical Field

[0001] This invention relates to the field of neutron application technology, and in particular to a neutron radiography method and a neutron radiography apparatus. Background Technology

[0002] Neutron radiography is a technique that uses a neutron beam emitted from a neutron source to achieve imaging, and it is widely used in industrial fields. When using neutron radiography in the image acquisition stage of non-destructive testing analyses such as quantitative analysis and tomography, multiple image data points need to be acquired. Because the exposure time for a single neutron radiograph image is relatively long, ranging from a few seconds to several minutes, the cumulative exposure time increases as the number of image data to be acquired grows. During this time, fluctuations in the neutron source intensity cause significant differences in the grayscale values ​​of the acquired image data. Directly applying this series of image data will lead to errors in quantitative analysis results or poor 3D reconstruction results. Summary of the Invention

[0003] In view of the above problems, the present invention is proposed to provide a neutron radiography method and system that overcomes or at least partially solves the above problems, aiming to solve the problem of image data distortion caused by strong fluctuations in neutron sources, and to improve the image quality of neutron radiography.

[0004] Specifically, the present invention provides the following technical solution:

[0005] A neutron radiography method, characterized by comprising:

[0006] Acquire the image to be corrected obtained by neutron radiography and the neutron fluence rate during neutron radiography, wherein there are at least two images to be corrected and the neutron fluence rate corresponds one-to-one with the images to be corrected.

[0007] The image to be corrected is normalized based on the neutron fluence rate.

[0008] Optionally, the method for normalizing the image to be corrected based on the neutron fluence rate includes:

[0009] The neutron fluence rate during each neutron imaging period is integrated to obtain the cumulative neutron fluence corresponding to the neutron imaging period;

[0010] Select the image to be corrected corresponding to the cumulative neutron fluence as the normalized image;

[0011] Based on the normalized image and the cumulative neutron fluence corresponding to each of the images to be corrected, the images to be corrected are normalized.

[0012] Optionally, the method for selecting an image to be corrected corresponding to the cumulative neutron fluence includes:

[0013] The neutron fluence rate during each neutron imaging period is integrated to obtain the cumulative neutron fluence corresponding to the neutron imaging period;

[0014] In response to the existence of at least three images to be corrected, the cumulative neutron fluences are sorted by size, and the image to be corrected corresponding to the cumulative neutron fluence at the middle value is obtained as the normalized image.

[0015] Optionally, the method for selecting an image to be corrected corresponding to the cumulative neutron fluence includes:

[0016] In response to two neutron imaging periods, the magnitudes of the cumulative neutron fluences are compared, and the image to be corrected corresponding to the smallest cumulative neutron fluence is used as the normalized image.

[0017] Based on the normalized image, each of the images to be corrected is normalized.

[0018] Optionally, the method for normalizing each of the images to be corrected based on the normalized image and the cumulative neutron fluence corresponding to each image to be corrected includes:

[0019] The cumulative neutron fluence corresponding to the normalized value image is used as the normalized value;

[0020] The cumulative neutron fluence is calculated pixel-by-pixel based on the relative value of each cumulative neutron fluence to the normalized value.

[0021] Optionally, the method for obtaining the image to be corrected obtained by neutron radiography and the neutron fluence rate during neutron radiography includes:

[0022] To obtain the beam space of neutron source radiation;

[0023] Adjust the position of the fluence rate measuring instrument at the edge of the beam space until the sampled value of the neutron fluence rate and the image quality of the image to be corrected meet the preset conditions.

[0024] Optionally, the method for obtaining the image to be corrected obtained by neutron radiography and the neutron fluence rate during neutron radiography includes:

[0025] The acquisition time of the image to be corrected and the acquisition time of the neutron fluence rate are synchronized so as to acquire the neutron fluence rate within the acquisition time of the image to be corrected.

[0026] On the other hand, the present invention also provides a neutron radiography system, the neutron radiography system comprising a neutron source, an image acquisition device, and at least one flux rate meter. The neutron source is configured to release a neutron beam in a beam space; the image acquisition device is configured to acquire neutrons and generate an image to be corrected; the flux rate meter is disposed between the neutron source and the image acquisition device for measuring the neutron flux rate of the neutron beam.

[0027] Optionally, the flux rate measuring instrument is located at the edge of the beam space.

[0028] Optionally, the neutron radiography system further includes a control device connected to the image acquisition device and the fluence rate measuring instrument, and configured to:

[0029] In response to the control device including different control units connected to the image acquisition device and the fluence rate measuring instrument, the data acquisition time of each control unit is synchronized to acquire the neutron fluence rate within the acquisition time of the image to be corrected; or

[0030] The control device includes the same control unit connected to the image acquisition device and the injection rate measuring instrument.

[0031] The technical solution provided in this application acquires the neutron fluence during neutron radiography while obtaining the image to be corrected. The neutron fluence reflects the fluctuation of the neutron source intensity, and the image to be corrected is normalized and corrected to reduce the image data distortion caused by the fluctuation of the neutron source intensity, thereby improving the image quality of neutron radiography.

[0032] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0033] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0034] Figure 1 This is a flowchart of a neutron radiography method according to an embodiment of the present invention;

[0035] Figure 2 This is a flowchart of a method for normalizing an image to be corrected based on neutron fluence rate according to an embodiment of the present invention;

[0036] Figure 3This is a flowchart of a method for normalizing each image to be corrected based on a normalized image and the cumulative neutron fluence corresponding to each image to be corrected, according to an embodiment of the present invention.

[0037] Figure 4 This is a flowchart of a method for obtaining an image to be corrected obtained by neutron radiography and the neutron fluence rate during neutron radiography, according to an embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of obtaining the cumulative neutron fluence by integrating the neutron fluence rate according to an embodiment of the present invention;

[0039] Figure 6 This is a schematic structural diagram of a neutron radiography system according to an embodiment of the present invention. Detailed Implementation

[0040] The following reference Figures 1 to 6 This invention describes a neutron radiography method and system according to embodiments of the present invention. In this description, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature, that is, include one or more of that feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. When a feature "includes or contains" one or more of the features it encompasses, unless otherwise specifically described, this indicates that other features are not excluded and may be further included.

[0041] Unless otherwise expressly specified and limited, the terms "set up," "install," "connect," "link," "fix," and "couple" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art should be able to understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] Furthermore, in the description of this embodiment, "above" or "below" the second feature can include direct contact between the first and second features, or it can include contact between the first and second features through another feature between them. That is, in the description of this embodiment, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "below" of the second feature can mean the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0043] In the description of this embodiment, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] Figure 1 This is a flowchart of a neutron radiography method according to an embodiment of the present invention, which is described below in conjunction with... Figure 1-6 This paper provides a detailed description of the neutron radiography method and system described in this application.

[0045] like Figure 1 As shown, a neutron radiography method according to an embodiment of the present invention includes:

[0046] S100 acquires the image to be corrected obtained by neutron radiography and the neutron fluence during neutron radiography, wherein there are at least two images to be corrected and the neutron fluence corresponds one-to-one with the images to be corrected.

[0047] S200 normalizes the image to be corrected based on the neutron fluence rate.

[0048] The exposure time for a single image in neutron radiography is relatively long, and the cumulative exposure time continues to increase as the amount of image data to be acquired increases. Generally, neutron source 1 can be considered a stable source for a short period, but as the cumulative exposure time increases, the strong fluctuations in neutron source 1 must be considered. To mitigate this effect, this invention proposes recording the changes in neutron flux rate during neutron radiography and then using these fluctuations to correct the image. Specifically, in this embodiment, the neutron flux rate is acquired simultaneously with the neutron radiography image to be corrected. One objective of this embodiment is to correct the inconsistency in image data generated by the strong fluctuations in neutron source 1 across multiple images to be corrected; that is, the image data of multiple images to be corrected are adjusted according to their corresponding neutron flux rates to simulate images formed under the same or a specific stable neutron source 1. Therefore, after obtaining the neutron fluence rate during neutron radiography, the images to be corrected can be normalized according to the different neutron fluence rates corresponding to different images, thereby reducing the image data distortion caused by fluctuations in the neutron source and improving the image quality of neutron radiography.

[0049] In some embodiments of the neutron radiography method of the present invention, such as Figure 2 As shown, the methods for normalizing the image to be corrected based on the neutron fluence rate include:

[0050] S210 integrates the neutron fluence rate during each neutron imaging period to obtain the cumulative neutron fluence J corresponding to the neutron imaging period. i ;

[0051] S220 selects an image to be corrected corresponding to the cumulative neutron fluence as the normalized image;

[0052] S230 normalizes each image to be corrected based on the normalized image and the cumulative neutron fluence corresponding to each image to be corrected.

[0053] In this embodiment, as Figure 5 As shown, Figure 5 The horizontal axis represents time, and the vertical axis represents the acquired neutron fluence rate. Fluctuations in neutron source 1 are typically irregular, primarily manifested as irregular fluctuations in the neutron fluence rate over time. To reflect the neutron fluence rate over the entire exposure time, it is necessary to integrate the neutron fluence rate with respect to time to obtain the cumulative neutron fluence. For example, the starting time of the exposure time for one neutron photograph is T. S1 The end time is T e1 The cumulative neutron fluence J1 is the integral of the neutron fluence rate over time, that is... Figure 5 The horizontal axis of the coordinate system is parallel to T. S1 T e1The area enclosed by the cumulative neutron flux rate, neutron flux, and neutron emission rate. The cumulative neutron flux significantly affects the grayscale value of the image to be corrected. With photographic sample 3 unchanged and the same exposure time, the overall grayscale value of the images to be corrected varies under different cumulative neutron fluxes. Generally, the grayscale value of the image to be corrected is proportional to the cumulative neutron flux. Therefore, by selecting one image from multiple images to be corrected as the normalized image, and then normalizing each image based on the normalized image and the corresponding cumulative neutron flux, the influence of fluctuations in the cumulative neutron flux on the neutron-photographed image can be corrected. Specifically, the cumulative neutron flux corresponding to the normalized image is set as the normalized value J. s The grayscale value of each image to be corrected is f i The cumulative neutron fluence corresponding to each image to be corrected is J. i Then the formula for normalization is:

[0054] f i Repair = f i *J i / J s

[0055] In the above formula, f i The grayscale value of the image after normalization. For example, the grayscale value of a normalized image is f1modified = f1 * J1 / J. s .

[0056] In some embodiments of the neutron radiography method of the present invention, the method for normalizing the image to be corrected based on the neutron fluence rate includes:

[0057] S240 responds to the use of two or more flux rate measuring instruments 2, each measuring the neutron flux rate at a location, integrating the neutron flux rate acquired by each flux rate measuring instrument 2 during each neutron imaging period, and summing multiple integrated values ​​for the same neutron imaging period to obtain the cumulative neutron flux J corresponding to the neutron imaging period. i ;

[0058] S220 selects an image to be corrected corresponding to the cumulative neutron fluence as the normalized image;

[0059] S230 normalizes each image to be corrected based on the normalized image and the cumulative neutron fluence corresponding to each image to be corrected.

[0060] In this embodiment, multiple flux rate measuring instruments 2 are used. The neutron flux rate obtained by each flux rate measuring instrument 2 is integrated and then added together. In this way, the obtained cumulative neutron flux can more accurately reflect the cumulative neutron flux at sample 3 or the middle of the neutron beam, and further improve the accuracy of the correction of the image to be corrected.

[0061] In some embodiments of the neutron radiography method of the present invention, the method for selecting an image to be corrected corresponding to a cumulative neutron fluence includes:

[0062] S221 responds to the fact that there are at least three images to be corrected, sorts the cumulative neutron fluences according to their size, and obtains the image to be corrected corresponding to the cumulative neutron fluence at the middle value as the normalized image.

[0063] In neutron radiography, due to fluctuations in the cumulative neutron fluence, the obtained image to be corrected may sometimes be overexposed or underexposed. In other words, an abnormally exposed image to be corrected cannot accurately reflect the cumulative neutron fluence. Using an abnormally exposed image to be corrected as a normalized image will adversely affect the normalization process of all images to be corrected. In this embodiment, to avoid or reduce this situation, the cumulative neutron fluence at the median value is selected from all cumulative neutron fluence values, and its corresponding image to be corrected is used as the normalized image. The grayscale value of this normalized image can better reflect its corresponding cumulative neutron fluence. Using this as a basis for normalizing other images to be corrected yields a more accurate image.

[0064] In some embodiments of the neutron radiography method of the present invention, the method for selecting an image to be corrected corresponding to a cumulative neutron fluence includes:

[0065] S222 responds to two events during neutron imaging, comparing the magnitudes of each cumulative neutron fluence, and using the image to be corrected corresponding to the smallest cumulative neutron fluence as the normalized image.

[0066] In this embodiment, when two images to be corrected are obtained from neutron imaging, the image with the smaller cumulative neutron fluence is selected as the normalized image. A smaller cumulative neutron fluence generally corresponds to smaller fluctuations in the neutron fluence rate. Compared to a larger cumulative neutron fluence, the image with the smaller cumulative neutron fluence better reflects the neutron fluence rate at a relatively stable neutron source. Using the image with the smaller cumulative neutron fluence as the normalized image, and then normalizing other images based on it, yields more accurate images.

[0067] In some embodiments of the neutron radiography method of the present invention, such as Figure 3 As shown, the method for normalizing each image to be corrected based on the normalized image and the cumulative neutron fluence corresponding to each image to be corrected includes:

[0068] S231 uses the cumulative neutron fluence corresponding to the normalized value image as the normalized value;

[0069] S232 calculates each image to be corrected pixel by pixel based on the relative value of each cumulative neutron fluence to the normalized value.

[0070] In this embodiment, according to current neutron radiography technology, each pixel of the obtained image to be corrected is generally proportional to the cumulative neutron flux at sample location 3 or the middle of the neutron beam corresponding to that pixel. Since the cumulative neutron flux at sample location 3 or the middle of the neutron beam is proportional to the cumulative neutron flux, therefore, for each pixel of the image to be corrected, the grayscale value f... i Normalization correction f i修 It can be directly processed using the following formula:

[0071] f i修 =f i *J i / J s

[0072] In the above formula, f i修 J represents the grayscale value of each pixel in the normalized image. s For the normalized value, f i J represents the grayscale value of each pixel in the image to be corrected. i This represents the cumulative neutron fluence corresponding to the image to be corrected.

[0073] In some embodiments of the neutron radiography method of the present invention, such as Figure 4 and Figure 6 As shown, the method for obtaining the image to be corrected obtained by neutron radiography and the neutron fluence rate during neutron radiography includes:

[0074] S111 obtains the beam space of radiation from neutron source 1;

[0075] S112 adjusts the position of the fluence meter 2 at the edge of the beam space until the sampled value of the neutron fluence and the image quality of the image to be calibrated meet the preset conditions.

[0076] Obtaining neutron fluence requires the placement of a fluence rate measuring instrument 2. Since the position of the fluence rate measuring instrument 2 significantly affects measurement accuracy, and also influences the quality of the neutron beam, thus affecting the quality of the neutron radiograph image, in this embodiment, to simultaneously ensure the measurement accuracy of the neutron fluence rate and the quality of the neutron radiograph image, the fluence rate measuring instrument 2 is placed at the edge of the beam used for neutron radiographing. The specific position of the fluence rate measuring instrument 2 is determined through multiple trials to ensure that the neutron fluence rate at that position is proportional to the neutron fluence rate at the sample 3 or the center of the neutron beam. For example, before neutron imaging, a fluence rate measuring instrument 2 is placed at both the beam edge and the beam center to measure neutron fluence rate samples for multiple exposure times. The samples measured at the beam edge and the samples measured at the beam center are compared to see if they are proportional. If they are not proportional, the position of the fluence rate measuring instrument 2 at the beam edge is changed multiple times until they are proportional. This ensures that the measurement data from the flux rate meter 2 accurately reflects the neutron flux at sample 3 or the middle of the neutron beam, providing an accurate basis for subsequent data correction. On the other hand, after setting up the flux rate meter 2 and sample 3, test images can be taken to check if the image quality of the acquired image to be corrected meets the preset conditions. If it does not meet the preset conditions, it indicates that the flux rate meter 2 has a significant impact on the image to be corrected, and the position of the flux rate meter 2 needs further adjustment to reduce its influence on the image.

[0077] In some embodiments of the neutron radiography method of the present invention, the method for obtaining the image to be corrected obtained by neutron radiography and the neutron fluence rate during neutron radiography includes:

[0078] S121 synchronizes the acquisition time of the image to be corrected and the acquisition time of the neutron fluence rate, so as to acquire the neutron fluence rate within the acquisition time of the image to be corrected.

[0079] In this embodiment, to ensure that the neutron fluence rate acquired by the fluence rate measuring instrument 2 accurately reflects the image to be calibrated, the time of the fluence rate measuring instrument 2 and the time of the image acquisition device 4 need to be synchronized. Specifically, one synchronization method is to simultaneously turn the fluence rate measuring instrument 2 and the image acquisition device 4 on and off, ensuring that the start and end times of exposure for each image to be calibrated are consistent with the start and end times of the acquired neutron fluence rate. Another synchronization method is to keep the fluence rate measuring instrument 2 continuously on, and the image acquisition device 4 records the start and end times of each exposure, and then extracts the fluence rate measurement data within the start and end times.

[0080] In some embodiments of the neutron radiography system of the present invention, such as Figure 6As shown, the neutron radiography system includes a neutron source 1, an image acquisition device 4, and at least one flux rate measuring instrument 2. The neutron source 1 is configured to release a neutron beam in the beam space; the image acquisition device 4 is configured to acquire neutrons and generate an image to be corrected; the flux rate measuring instrument 2 is located between the neutron source 1 and the image acquisition device 4 and is used to measure the neutron flux rate of the neutron beam.

[0081] In this embodiment, when the neutron radiography system is used to monitor the neutron source 1, the flux rate measuring instrument 2 can be placed between the neutron source 1 and the image acquisition device 4. When the neutron radiography system is used to non-destructively photograph the sample 3, such as... Figure 6 As shown, sample 3 is placed between neutron source 1 and image acquisition device 4, and flux rate measuring instrument 2 is placed between neutron source 1 and sample 3, such that the neutron flux rate at the location of flux rate measuring instrument 2 is proportional to the neutron flux rate at sample 3. In this embodiment, flux rate measuring instrument 2 can be selected as a long counter or a fission ionization chamber. Long counters or fission ionization chambers have higher measurement accuracy for neutron flux rate, which can improve the correction accuracy of the image to be corrected using neutron flux rate.

[0082] In some embodiments of the neutron radiography system of the present invention, such as Figure 6 As shown, the flux rate meter 2 is located at the edge of the beam space. In this embodiment, when the sample 3 is large, the flux rate meter 2 will affect the quality of the neutron beam, thereby affecting the quality of the neutron radiograph. Therefore, the flux rate meter 2 is placed at the edge of the beam space to reduce its impact on the quality of the neutron radiograph.

[0083] In some embodiments of the neutron radiography system of the present invention, the neutron radiography system further includes a control device, which is connected to the image acquisition device 4 and the flux rate measuring instrument 2, and is configured as follows:

[0084] In response to the control device including different control units connected to the image acquisition device 4 and the flux rate measuring instrument 2, the data acquisition time of each control unit is synchronized so as to acquire the neutron flux rate within the acquisition time of the image to be corrected.

[0085] In this embodiment, the control device is a computer. The first computer is connected to the image acquisition device 4, controls the image acquisition device 4, and acquires data from the image acquisition device 4. This computer can also be used to perform data analysis on the image data. The second computer is connected to the image acquisition device 4 and is synchronized with the first computer in time. The second computer controls the injection rate measuring instrument 2 and acquires data from the injection rate measuring instrument 2.

[0086] In some embodiments of the neutron radiography system of the present invention, the neutron radiography system further includes a control device, which is connected to the image acquisition device 4 and the flux rate measuring instrument 2, and is configured as follows:

[0087] The control device includes the same control unit connected to the image acquisition device 4 and the injection rate measuring instrument 2.

[0088] In this embodiment, the control device is a computer connected to the image acquisition device 4, which controls the image acquisition device 4 and acquires its data. The computer can also be used for data analysis of the image data. The computer is also connected to the image acquisition device 4, controls the injection rate measuring instrument 2, and acquires its data.

[0089] In some embodiments of the neutron radiography system of the present invention, such as Figure 6 As shown, there are two fluence rate measuring instruments 2, each located at a different position in the neutron beam. The fluctuations in neutron fluence rate at different locations within the neutron beam may be inconsistent. When there is only one fluence rate measuring instrument 2, the fluctuations in neutron fluence rate at the location of instrument 2 may differ from those at sample 3 or the center of the neutron beam, leading to a failure of the normalized value to accurately reflect the cumulative neutron fluence at sample 3 or the center of the neutron beam. To address this issue, this embodiment employs two fluence rate measuring instruments 2, each located at a different position in the neutron beam. This allows the neutron fluence rate obtained by instrument 2 to more accurately reflect the neutron fluence rate at sample 3 or the center of the neutron beam, further improving the accuracy of the correction to the image to be corrected.

[0090] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A neutron radiography method, characterized in that, include: Acquire the image to be corrected obtained by neutron radiography and the neutron fluence rate during neutron radiography, wherein there are at least two images to be corrected and the neutron fluence rate corresponds one-to-one with the images to be corrected; The image to be corrected is normalized based on the neutron fluence rate. The normalization process for the image to be corrected based on the neutron fluence rate includes: The neutron fluence rate during each neutron imaging period is integrated to obtain the cumulative neutron fluence corresponding to the neutron imaging period; Select the image to be corrected corresponding to the cumulative neutron fluence as the normalized image; Based on the normalized image and the cumulative neutron fluence corresponding to each of the images to be corrected, the images to be corrected are normalized.

2. The neutron radiography method according to claim 1, characterized in that, Selecting an image to be corrected corresponding to the cumulative neutron fluence includes: In response to the existence of at least three images to be corrected, the cumulative neutron fluences are sorted by size, and the image to be corrected corresponding to the cumulative neutron fluence at the middle value is obtained as the normalized image.

3. The neutron radiography method according to claim 1, characterized in that, Selecting an image to be corrected corresponding to the cumulative neutron fluence includes: In response to two neutron imaging periods, the magnitudes of the cumulative neutron fluences are compared, and the image to be corrected corresponding to the smallest cumulative neutron fluence is used as the normalized image. Based on the normalized image, each of the images to be corrected is normalized.

4. The neutron radiography method according to claim 1, characterized in that, The normalization process for each image to be corrected, based on the normalized image and the cumulative neutron fluence corresponding to each image to be corrected, includes: The cumulative neutron fluence corresponding to the normalized value image is used as the normalized value; The cumulative neutron fluence is calculated pixel-by-pixel based on the relative value of each cumulative neutron fluence to the normalized value.

5. The neutron radiography method according to claim 1, characterized in that, The acquisition of the image to be corrected obtained by neutron radiography and the neutron fluence rate during neutron radiography includes: To obtain the beam space of neutron source radiation; Adjust the position of the fluence rate measuring instrument at the edge of the beam space until the sampled value of the neutron fluence rate and the image quality of the image to be corrected meet the preset conditions.

6. The neutron radiography method according to claim 1, characterized in that, The acquisition of the image to be corrected obtained by neutron radiography and the neutron fluence rate during neutron radiography includes: The acquisition time of the image to be corrected and the acquisition time of the neutron fluence rate are synchronized so as to acquire the neutron fluence rate within the acquisition time of the image to be corrected.

Images