A method for adjusting radionuclide data values

Abstract

The present invention discloses a method for adjusting radionuclide data values, which belongs to the technical field of radionuclide measurement, and includes: determining the peak interval of the radionuclide according to the gamma energy spectrum curve obtained by measurement, and finding the peak position of the radionuclide by peak search; performing Gaussian fitting on the energy spectrum data in the peak interval to form a fitting curve; calculating the local detail adjustment value corresponding to each channel address in the fitting curve; calculating the fitting curve adjustment value corresponding to each channel address; adjusting the fitting curve value corresponding to each channel address to obtain the adjusted radionuclide energy spectrum data. The radionuclide data value adjustment method of the present invention is not limited by the accumulation time, nor is it affected by the interference of the marine environment. It can accurately adjust the energy peak corresponding to the radionuclide to obtain radionuclide data that is closer to the true value, and can automatically filter out some obvious false peaks, so that the accuracy of peak search is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of radionuclide measurement, and in particular relates to a method for adjusting radionuclide data values. Background Art

[0002] Radioactive substances in seawater mainly come from radioactive isotopes existing in nature, such as potassium-40 (K-40), uranium (U) and thorium (Th). These isotopes exist in the earth's crust and enter the ocean through weathering and erosion of rocks. In addition, radioactive substances in seawater may also come from human activities, such as nuclear war, nuclear leakage or discharge of radioactive waste. The increase in the content of radioactive substances in seawater will cause harm to the marine environment and ecosystem. Therefore, it is important and necessary to monitor radioactive substances in seawater.

[0003] At present, the industry generally uses gamma spectrometers to detect gamma rays released by radioactive substances in seawater, and then determine the content of radionuclides in it. For example, if a certain radionuclide exists in seawater, a corresponding energy peak will appear in its corresponding energy range. The type of radionuclide can be determined based on the peak position, and the content of the radionuclide can be calculated based on the amplitude of the energy peak.

[0004] However, existing seawater radioactive material monitoring methods are usually based on the assumption that the detection signal corresponding to the radioactive material to be tested in seawater is stable or unchanged. However, the actual marine field detection environment is complex and changeable, with many interference factors. Changes in the marine environment interfere with the measurement of marine radioactive materials. The phenomenon is that the amplitude of the detected energy peak will change irregularly, or there will be many peaks, including true peaks, false peaks, superimposed peaks, and error peaks caused by interference data. Therefore, it is difficult to quickly and accurately determine the true data of the energy peak corresponding to the radioactive material in seawater.

[0005] Based on the above reasons, during the measurement of radionuclides, a method must be found to adjust the detection value of radionuclides to obtain accurate data. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention proposes a method for adjusting radionuclide data values ​​to improve the accuracy of radionuclide detection results.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0008] A method for adjusting radionuclide data values, comprising:

[0009] Determining the peak interval of the radionuclide according to the gamma spectrum curve obtained by measurement, and finding the peak position of the radionuclide by peak searching;

[0010] Performing Gaussian fitting on the energy spectrum data within the peak interval to form a fitting curve;

[0011] Calculate the 2 corresponding to each address in the fitting curve m +1 local detail adjustment value K j :

[0012] ;

[0013] in, is the cosine square transformation function ; ; m for scale; h is the height;

[0014] Calculate the fitting curve adjustment value corresponding to each channel address:

[0015] ;

[0016] in, Ad i For road address X i The corresponding fitting curve adjustment value, X i ∈ peak interval; Y i+j For the address X i+j The corresponding fitting curve value; avg i For the address from X i-m arrive X i+m The average value of the corresponding fitting curve value; avg It is the average value of the fitting curve values ​​corresponding to all the addresses in the peak interval;

[0017] Adjust the fitting curve value corresponding to each address:

[0018] ;

[0019] in, For the address X i The corresponding adjusted radionuclide energy spectrum data; For the address X i The corresponding fitting curve value.

[0020] In some embodiments of the present application, the following Gaussian fitting function may be used to perform Gaussian fitting on the energy spectrum data within the peak interval:

[0021] ;

[0022] in, Y max is the peak value of the gamma energy spectrum curve; X max is the peak position; S / 2 It is the square of the half-height width of the energy peak.

[0023] In some embodiments of the present application, the scale m The half-width of the energy peak S / 2 Determine its value, and S / 2 The bigger, m The larger the value.

[0024] In some embodiments of the present application, the scale m The value can be between 1 and 5.

[0025] In some embodiments of the present application, the height h It can be determined based on the signal accumulation time of the radionuclide, and the longer the signal accumulation time, h The smaller the value.

[0026] In some embodiments of the present application, the height can be configured h =1.

[0027] In some embodiments of the present application, before searching for the peak interval and peak position of the radioactive nuclide, a process of smoothing and filtering the measured gamma spectrum curve may be added, which is helpful for finding the true peak position.

[0028] Compared with the prior art, the advantages and positive effects of the present invention are mainly reflected in:

[0029] 1. The radionuclide data value adjustment method of the present invention is not limited by the accumulation time, nor is it affected by the interference of the marine environment. It can accurately adjust the energy peak corresponding to the radionuclide to obtain radionuclide data closer to the true value, and can automatically filter out some obvious false peaks, so that the peak search accuracy can be improved;

[0030] 2. The radionuclide data value adjustment method of the present invention has a simple calculation process and is easy to implement, and can improve the efficiency and accuracy of radionuclide data adjustment.

[0031] Other features and advantages of the present invention will become more apparent after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can also obtain other drawings based on these drawings without creative work.

[0033] Figure 1 A flowchart of an embodiment of the method for adjusting the radionuclide data value proposed by the present invention;

[0034] Figure 2 It is a gamma spectrum curve obtained by measuring a seawater sample;

[0035] Figure 3 Yes Figure 2 The gamma spectrum curve shown is obtained by smoothing and filtering the gamma spectrum curve;

[0036] Figure 4 is from Figure 3 A peak search result diagram showing the peak interval and peak position of a certain radioactive nuclide;

[0037] Figure 5 Yes Figure 4 A comparison diagram of a fitting curve formed by Gaussian fitting of the gamma spectrum data within the peak interval determined in the figure and a gamma spectrum curve after smoothing filtering;

[0038] Figure 6 Yes Figure 5 An enlarged view of a section of the waveform involved in the fitting curve;

[0039] Figure 7 It is a comparison chart of the adjusted energy spectrum curve, the fitting curve, and the gamma energy spectrum curve after smoothing filtering. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] In order to eliminate the influence of interference factors on the radionuclide detection data and restore the true value of the radionuclide as much as possible, this embodiment proposes a method for adjusting the detected radionuclide data value, such as Figure 1 As shown, it mainly includes the following processes:

[0042] S101. Measure radioactive nuclides and obtain gamma energy spectrum curves of radioactive nuclides.

[0043] In some embodiments, a gamma spectrometer may be used to detect a sample to be tested (such as seawater) to obtain a gamma spectrum curve of the radioactive nuclides in the sample to be tested, such as Figure 2 shown.

[0044] Figure 2 In the figure, the horizontal axis is the channel address (i.e., the channel address, usually 1024 channels), and the vertical axis is the gamma count value. Different radionuclides will form energy peaks at different channel addresses. Therefore, the radionuclides contained in the sample to be tested can be determined according to the peak position of each energy peak in the gamma energy spectrum curve (the channel address corresponding to the peak), and then the content of each radionuclides can be determined according to the peak value of the energy peak (gamma count value). This part of the content is the existing technology, and this embodiment will not be described in detail here.

[0045] In other words, the process of detecting the type and content of radioactive nuclides in the sample to be tested is also the peak-finding process, and the peak-finding process is the process of finding the peak interval and peak position.

[0046] S102, performing smoothing filtering on the gamma spectrum curve.

[0047] The purpose of smoothing and filtering the detection data corresponding to all channel addresses is to find the true peak position without affecting the curve waveform during the peak search process, and it does not affect the final calculation result.

[0048] right Figure 2 The gamma spectrum curve shown in FIG. 1 is smoothed and filtered, for example, the gamma spectrum curve is smoothed using a smooth function, and the following can be obtained after the processing: Figure 3 The energy spectrum curve is shown.

[0049] S103. Determine the peak interval of the radioactive nuclide.

[0050] The peak range of a radionuclide is the range of energy peaks formed by the radionuclide in the gamma spectrum curve.

[0051] At present, there are many methods for finding the peak range of radioactive nuclides. You can refer to the peak range finding method disclosed in the Chinese patent application "A method for determining the peak range of seawater radioactive nuclides" with publication number CN113009544A.

[0052] S104. Peak search to find the peak position of the radioactive nuclide.

[0053] That is, within the determined peak interval, the gamma count values ​​corresponding to each channel address are traversed, the maximum value is found as the peak value, and then the channel address corresponding to the peak value is determined, which is the peak position of the radionuclide.

[0054] At present, there are many methods for finding the peak position of radioactive nuclides. You can refer to the peak position finding method disclosed in the Chinese patent application "A Rapid Peak Finding Method for Detecting Radioactive Substances in Seawater" with publication number CN108333617A.

[0055] by Figure 3 Taking the energy spectrum curve shown in FIG. 1 as an example, for the second energy peak in the energy spectrum curve, through the above steps S103 and S104, it can be found that the peak interval of the energy peak is "channel address 348-394" and the peak position is "channel address 371". Figure 4 shown.

[0056] S105 , performing Gaussian fitting on the energy spectrum data within the peak interval to form a fitting curve.

[0057] The Gaussian fitting function is used to perform Gaussian fitting on the energy spectrum data within the peak interval of the radionuclide determined in step S103 to form a Gaussian fitting curve, such as Figure 5 , Figure 6 Curve A in .

[0058] In this embodiment, the Gaussian fitting function can be expressed by the following formula:

[0059] ;

[0060] in, X i is the horizontal coordinate of the fitting curve, that is, the track address, and X i ∈ peak interval; For the address X i The corresponding fitting curve value, that is, X i The corresponding vertical coordinate value; X max is the peak position of the gamma spectrum curve after filtering; Y max is the peak value of the gamma spectrum curve after filtering, that is, X max The corresponding vertical coordinate value; S / 2 It is the square of the half-height width of the energy peak.

[0061] Thus, the Gaussian fitting curve is obtained. .

[0062] S106: Calculate the local detail adjustment value corresponding to each track address in the fitting curve.

[0063] In order to eliminate interference, this embodiment first determines the 2 corresponding to each address. m +1 local detail adjustment value K j , Then, using the 2 m +1 local detail adjustment value K j The front of the address m The address, after m The adjustment value of the fitting curve corresponding to each channel address is calculated by combining the channel address and the fitting curve value corresponding to the channel address itself. Ad i ; Finally, use the adjustment value of the fitting curve Ad i The fitting curve value corresponding to each channel address in the Gaussian fitting curve is adjusted to obtain the approximate true value after eliminating interference.

[0064] In some embodiments, the following formula can be used to calculate the 2 corresponding to each address in the fitting curve: m +1 local detail adjustment value K j :

[0065] ;

[0066] in, is the cosine square transformation function:

[0067] ;

[0068] σ is the mean value of the cosine square transformation function:

[0069] ;

[0070] m for scale; h For height.

[0071] In this embodiment, the scale m Determines the reference width for local detail adjustment w , w =2 m +1, according to the half-height width of the energy peak S / 2 Determine its specific value and follow S / 2 The bigger, m The bigger; S / 2 The smaller, m The smaller the value, the better.

[0072] Usually, the scale m It can take values ​​between 1 and 5. For example, when the scale m When the value is 3, the width w =7, that is, take 3 points on the left and right sides of the current address, add 1 point of itself, and use 7 points to calculate the local detail adjustment value of the current address.

[0073] If the half-width of the energy peak S / 2 is relatively large, that is, the waveform of the energy peak is relatively wide, such as Figure 5 The third energy peak in the image can be taken with more points, that is, increasing m For example, you can set m =5, take 11 points to calculate the local detail adjustment value of each channel address. On the contrary, if the half-height width of the energy peak S / 2 is relatively small, that is, the waveform of the energy peak is relatively narrow, such as Figure 5 The second energy peak in the image can be reduced by taking fewer points, that is, m For example, setting m =2 or m =1, taking 5 points or 3 points to calculate the local detail adjustment value of each channel address can also meet the accuracy requirements of the adjusted radionuclide data value.

[0074] Of course, you can also set different m Value, that is, it can be adjusted at any time according to actual conditions m The specific value of can be adjusted to adapt to different monitoring environments.

[0075] high h The value of determines the increase or decrease of the fitting curve, and its purpose is to find the real peak and restore the real shape and size of the radionuclide energy peak, that is, to make the adjusted fitting curve closer to the shape of the Gaussian curve. Since the data value corresponding to each channel address is the result of signal accumulation, due to the existence of errors such as detection signals, the actual situation is definitely not 100% in line with the shape of the Gaussian curve. Therefore, the height can be reasonably adjusted according to the signal accumulation time of the radionuclide. h to eliminate the error influence as much as possible.

[0076] In this embodiment, the longer the signal accumulation time of the radionuclide is, h The smaller the value, the shorter the signal accumulation time. h The larger the value, the more likely it is to be determined. h Specific value of. Usually, you can set the height h =1.

[0077] S107: Calculate the adjustment value of the fitting curve corresponding to each track address according to the local detail adjustment value.

[0078] After calculating the local detail adjustment value K j After that, the adjustment value of the fitting curve corresponding to each channel address can be calculated using the following formula:

[0079] ;

[0080] in, Ad i For the address X i The corresponding fitting curve adjustment value; Y i+j For the address X i+j The corresponding fitting curve value; avg i For the address from X i-m arrive X i+m The average value of the corresponding fitting curve value, that is, 2 m + the average of 1 adjacent fitted curve values; avg is the average value of the fitting curve corresponding to all the addresses in the peak interval. For example, the energy peak of the peak interval "address 348-394" has avg It is the average value of the 47 fitting curve values ​​corresponding to the addresses from 348 to 394.

[0081] S108. According to the fitting curve adjustment value corresponding to each channel address, the data value of the fitting curve is adjusted to obtain adjusted radionuclide energy spectrum data.

[0082] In this embodiment, the fitting curve value corresponding to each channel address can be adjusted using the following formula:

[0083] ;

[0084] in, For the address X i The corresponding adjusted radionuclide energy spectrum data.

[0085] like Figure 7 As shown in the figure, curve B is the original gamma spectrum curve after smooth filtering; curve A is the Gaussian fitting curve; and curve C is the adjusted radionuclide spectrum curve. Among them, curve C is closer to the real spectrum data of the radionuclide.

[0086] Of course, the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A method for adjusting radionuclide data values, characterized in that: include: Determining the peak interval of the radionuclide according to the gamma spectrum curve obtained by measurement, and finding the peak position of the radionuclide by peak searching; Performing Gaussian fitting on the energy spectrum data within the peak interval to form a fitting curve; Calculate the 2 corresponding to each address in the fitting curve m +1 local detail adjustment value K j : ; in, is the cosine square transformation function ; ; m for scale; h is the height; Calculate the fitting curve adjustment value corresponding to each channel address: ； in, Ad i For road address X i The corresponding fitting curve adjustment value, X i ∈ peak interval; Y i+j For the address X i+j The corresponding fitting curve value; avg i For the address from X i-m arrive X i+m The average value of the corresponding fitting curve value; avg It is the average value of the fitting curve values ​​corresponding to all the addresses in the peak interval; Adjust the fitting curve value corresponding to each address: ； in, For the address X i The corresponding adjusted radionuclide energy spectrum data; For the address X i The corresponding fitting curve value.

2. The method for adjusting radionuclide data value according to claim 1, characterized in that: The Gaussian fitting function used for Gaussian fitting of the energy spectrum data within the peak interval is: ； in, Y max is the peak value of the gamma energy spectrum curve; X max is the peak position of the gamma spectrum curve; S / 2 It is the square of the half-height width of the energy peak.

3. The method for adjusting radionuclide data value according to claim 1, characterized in that: The scale m According to the half-width of the energy peak S / 2 Determine its value, and S / 2 The bigger, m The larger the value.

4. The method for adjusting radionuclide data value according to claim 3, characterized in that: The scale m The value is between 1 and 5.

5. The method for adjusting radionuclide data value according to claim 1, characterized in that: The height h It is determined by the signal accumulation time of the radionuclide, and the longer the signal accumulation time, h The smaller the value.

6. The method for adjusting radionuclide data value according to claim 5, characterized in that: The height h =1.

7. The method for adjusting radionuclide data value according to any one of claims 1 to 6, characterized in that: Before finding the peak interval and peak position of the radioactive nuclide, the process also includes smoothing and filtering the measured gamma energy spectrum curve.

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