A method for evaluating the quenching degree of scintillation fluid

Abstract

The present invention relates to a method for evaluating the quenching degree of a scintillation fluid. The method comprises irradiating the same amount of scintillation fluid to be tested at the same location with a gamma radiation source, measuring the scintillation fluids to be tested to obtain corresponding liquid scintillation spectra, obtaining peak counts of the liquid scintillation spectra corresponding to each scintillation fluid to be tested, and finding a trace value N at a point with a preset percentage of peak counts on the right side of the peak of the liquid scintillation spectrum. A blank liquid scintillation device is irradiated at the same location with a gamma radiation source, obtaining a trace value N0 at a point with a preset percentage of peak counts on the right side of the peak of the blank sample beta spectrum. The quenching degree parameter Q of the scintillation fluid is defined based on the trace values ​​N and N0, and the quenching degree of the scintillation fluid to be tested is evaluated by comparing the quenching degree parameters Q of the scintillation fluids to be tested. The method disclosed in the present invention does not consume radioactive standard sources and radioactive standard solutions, nor does it generate radioactive waste liquid. It has the advantages of being convenient, fast, safe, environmentally friendly, and low-cost.

Description

Technical Field

[0001] The invention belongs to the field of scintillation fluid performance evaluation, and in particular relates to a scintillation fluid quenching degree evaluation method. Background Art

[0002] Liquid scintillation analysis technology is currently the main method for measuring β-nuclides. Its principle is that β-nuclides emit β rays, which excite the scintillation liquid to produce photons. The light signal is measured by a photomultiplier tube, thereby realizing the measurement of β-nuclide activity.

[0003] Scintillation fluid is the primary reagent for liquid scintillation measurement of beta-nuclides. The channel width of a liquid scintillation spectrum is positively correlated with the energy of the radiation, resulting in different channel widths for different energies of beta-nuclides. Quenching occurs when photons generated by beta-ray scintillation are absorbed during their journey to the photomultiplier tube (PMT), resulting in a weakened signal. Quenching can be categorized as chemical quenching, caused by absorption by chemical substances, or color quenching, caused by absorption by colored substances. Scintillation fluids are typically complex in composition and can inherently cause varying degrees of quenching.

[0004] Some radiopharmaceuticals require radionuclide identification. For β-nuclides, liquid scintillation spectrometry is required for this purpose. This requires a scintillation fluid with minimal self-quenching, such as an unquenched scintillation fluid. Furthermore, scintillation fluids with low self-quenching have higher detection efficiency. Under the same conditions, scintillation fluids with low quenching can produce more accurate measurement results. Therefore, evaluating the quenching degree of a scintillation fluid can also help select the appropriate scintillation fluid for β-nuclides.

[0005] Due to the different components of scintillation fluid, there are different degrees of quenching. The quenching degree of the scintillation fluid itself can usually be reflected by the detection efficiency of a certain nuclide.

[0006] The self-quenching degree of scintillation fluid is usually evaluated by comparing the detection efficiency of scintillation fluid for a certain nuclide under the same conditions. For example, a small volume of a certain activity is added to the scintillation fluid. 14 C standard radionuclide measurement, calculation 14 The higher the detection efficiency, the lower the quenching degree of the scintillation fluid. 14 C standard without quenching source sample detection efficiency compared, if the detection efficiency of the scintillation liquid is 14 If the C standard is consistent with the unquenched source sample, the scintillation fluid can be considered as unquenched scintillation fluid and can be used for the identification of β nuclides. The main disadvantages of this method are twofold. First, 14 C standard radionuclides are expensive and require a certain amount of radioactive standard solution, making the cost of evaluating the quenching degree of scintillation fluid high. Secondly, the mixing of scintillation fluid and radionuclides produces radioactive waste, which is difficult and costly to dispose of. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention provides a method for evaluating the quenching degree of scintillation fluid. This method utilizes the characteristics of a gamma-radiation source generating Compton electrons, which in turn excite the scintillation fluid to produce photons, to assess the quenching degree of the scintillation fluid. This method does not consume a radioactive standard source or radioactive standard solution, nor does it generate radioactive waste. It offers the advantages of convenience, safety, environmental protection, and low cost.

[0008] To achieve the above objectives, the present invention adopts a technical solution: a method for evaluating the quenching degree of scintillation fluid, comprising the following steps:

[0009] S1. Using a gamma radiation source to irradiate the same amount of scintillation liquid to be tested at the same position, and measuring the scintillation liquid to be tested to obtain corresponding liquid scintillation spectra;

[0010] S2. Obtain the peak counts of the liquid scintillation spectrum corresponding to each scintillation liquid to be tested, and find the value N of the point with a preset percentage of the peak count on the right side of the peak of the liquid scintillation spectrum;

[0011] S3. Irradiate a blank liquid scintillator device with a gamma radiation source at the same position, measure the blank liquid scintillator device to obtain a blank sample β spectrum, and obtain a trace value N0 of a point where the peak count of the curve to the right of the peak of the blank sample β spectrum is a preset percentage;

[0012] S4. Define the scintillation fluid quenching parameter Q according to the channel values ​​N and N0, and evaluate the quenching degree of the scintillation fluid to be tested by comparing the values ​​of the scintillation fluid quenching parameter Q corresponding to each scintillation fluid to be tested.

[0013] Furthermore, in step S1 , scintillation liquid to be tested is added to the liquid scintillation device respectively, and a gamma radiation source is set on the liquid scintillation device to measure the scintillation liquid to be tested respectively and obtain the corresponding liquid scintillation spectrum.

[0014] Furthermore, the gamma radiation source is a small-volume point source.

[0015] Furthermore, the gamma radiation source includes 137 Cs, 133 Baor 152 Eu.

[0016] Furthermore, the preset percentage ranges from 1% to 99%.

[0017] Furthermore, the scintillation fluid quenching parameter Q is defined by the following formula:

[0018]

[0019] Furthermore, in step S4, the larger the Q value is, the lower the quenching degree is. When Q=1, there is no quenching source.

[0020] Furthermore, the order of steps S1, S2 and S3 can be swapped.

[0021] Furthermore, the liquid scintillation device is a liquid scintillation bottle.

[0022] Furthermore, the gamma radiation source is arranged at the center of the bottom of the liquid scintillator device.

[0023] The beneficial technical effect of the present invention is that the disclosed method for evaluating the quenching degree of scintillation fluid does not consume radioactive standard solution during the evaluation process, reducing evaluation costs. Furthermore, no radioactive waste liquid is generated, reducing the difficulty and cost of waste disposal, and laying a reliable foundation for beta nuclide measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of an implementation environment of a method for evaluating the quenching degree of scintillation fluid according to an embodiment of the present invention;

[0025] Figure 2 A method for evaluating the quenching degree of a scintillation liquid according to an embodiment of the present invention is used 137 Liquid scintillation measurement spectrum obtained by measuring scintillation liquid with Cs radioactive source;

[0026] Among them: 1-liquid scintillation bottle, 2-scintillation fluid, 3- 137 Cs radioactive source. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] like Figure 1 As shown, embodiments of the present invention provide a method for assessing the quenching degree of scintillation fluid. This method is based on the fact that gamma rays can excite scintillation fluid to produce Compton electrons. Similar to beta rays, Compton electrons can also excite scintillation fluid to produce photons, and a liquid scintillation spectrum can also be obtained in a liquid scintillation counter. Gamma rays have much greater penetrating power than beta rays. Therefore, simply by attaching a gamma radiation source outside the scintillation fluid, Compton electrons can be excited and a liquid scintillation spectrum can be obtained. The present invention utilizes this characteristic of gamma rays to assess the quenching degree of scintillation fluid.

[0030] A method for evaluating the quenching degree of a scintillation fluid provided by an embodiment of the present invention comprises the following steps:

[0031] S1. Add the scintillation liquid to be tested into the liquid scintillation bottle, fix the γ radiation source at the center of the bottom, put it into the liquid scintillation instrument to measure and obtain the liquid scintillation spectrum corresponding to each scintillation liquid to be tested. The γ radiation source is a small volume point source, which can be137 Cs, 133 Baor 152 Eu.

[0032] In this example, 20 mL glass liquid scintillation vials were filled with 15 mL each of the following scintillation liquids: homemade unquenched scintillation liquid, Ultima Gold LLT scintillation liquid, Ultima Gold AB scintillation liquid, and HiSafe 3 scintillation liquid. 137 Cs radioactive source.

[0033] like Figure 1 As shown, the scintillation liquid 2 is contained in the liquid scintillation bottle 1. 137 The Cs radioactive source 3 is placed at the center of the bottom of the liquid scintillation bottle 1. The sample is placed in a Hidex300SL liquid scintillation instrument for measurement to obtain a β spectrum.

[0034] S2. Obtain the peak counts of the liquid scintillation spectrum corresponding to each scintillation liquid to be tested, and find the value N of the point where the peak counts are 10% on the right side of the peak of the liquid scintillation spectrum.

[0035] In this embodiment, the quenching parameter Q of the scintillation liquid is calculated based on the value N of the point with a preset percentage of peak counts on the curve to the right of the peak of the liquid scintillation spectrum. The preset percentage is 1%-99%, preferably 10%.

[0036] S3. Fix the γ radiation source at the center of the bottom of the unquenched standard source blank sample, place it in the liquid scintillation instrument to measure and obtain the β spectrum of the unquenched standard source blank sample, and obtain the value N0 of the point with the highest count of 10% on the right side of the spectrum of the unquenched standard source blank sample.

[0037] Continuing with the above example, Figure 2 As shown, the blank sample without quenching is fixed at the bottom 137 Cs radioactive source, the sample was placed in Hidex300SL liquid scintillation instrument for measurement, the β spectrum was obtained, and the N0 value was calculated to be 753.

[0038] S4. Define the quenching parameter Q of the scintillation liquid, the formula is as follows:

[0039]

[0040] The quenching degree of the scintillation fluid is evaluated by comparing the size of the Q value. The larger the Q value, the lower the quenching degree. When Q=1, there is no quenching source.

[0041] According to the N0 and N values ​​measured in steps S2 and S3, the Q values ​​of various scintillation liquids were calculated in combination with the scintillation liquid quenching parameter Q calculation formula in step S4, and the quenching degrees of various scintillation liquids were compared. The results are shown in Table 1.

[0042] Table 1. Quenching of various scintillation fluids

[0043] Scintillation fluid name N Q Homemade quench-free scintillation fluid 754 1.00 Ultima Gold LLT scintillation fluid 726 0.96 HiSafe 3 scintillation fluid 702 0.93 Ultima Gold AB 710 0.94

[0044] The table shows that the quenching degree of the various scintillation fluids decreases in the order of HiSafe 3 scintillation fluid > Ultima Gold AB > Ultima Gold LLT scintillation fluid > homemade unquenched scintillation fluid. The homemade unquenched scintillation fluid is unquenched scintillation fluid.

[0045] It should be noted that the order of steps S1, S2 and S3 can be swapped.

[0046] As can be seen from the above embodiments, the present invention discloses a method for evaluating the quenching degree of a scintillation fluid. The method comprises irradiating the same amount of scintillation fluid to be tested at the same location with a gamma radiation source, measuring each of the scintillation fluids to be tested to obtain corresponding liquid scintillation spectra. Peak counts are obtained for each scintillation fluid to be tested, and a trace value N is found for a point on the right side of the peak of the liquid scintillation spectrum that has a preset percentage of peak counts. A blank liquid scintillation device is irradiated at the same location with a gamma radiation source, and a trace value N0 is found for a point on the right side of the peak of the blank sample beta spectrum that has a preset percentage of peak counts. The quenching degree parameter Q of the scintillation fluid is defined based on the trace values ​​N and N0, and the quenching degree of the scintillation fluid to be tested is evaluated by comparing the values ​​of the quenching degree parameter Q for each scintillation fluid to be tested. The method disclosed in the present invention does not consume radioactive standard sources or radioactive standard solutions, nor does it generate radioactive waste liquid. It has the advantages of being convenient, fast, safe, environmentally friendly, and low-cost.

[0047] The method described in the present invention is not limited to the embodiments described in the specific implementation manner. Those skilled in the art may derive other implementation manners based on the technical solution of the present invention, which also fall within the scope of the technical innovation of the present invention.

Claims

1. A method for evaluating the quenching degree of a scintillation fluid, comprising the following steps: S1. Using a gamma radiation source to irradiate the same amount of scintillation liquid to be tested at the same position, and measuring the scintillation liquid to be tested to obtain corresponding liquid scintillation spectra; S2. Obtain the peak counts of the liquid scintillation spectrum corresponding to each scintillation liquid to be tested, and find the value N of the point with a preset percentage of the peak count on the right side of the peak of the liquid scintillation spectrum; S3. Irradiate a blank liquid scintillator device with a gamma radiation source at the same position, measure the blank liquid scintillator device to obtain a blank sample β spectrum, and obtain a trace value N0 of a point where the peak count of the curve to the right of the peak of the blank sample β spectrum is a preset percentage; S4, defining the quenching parameter Q of the scintillation fluid according to the channel values ​​N and N0, and evaluating the quenching degree of the scintillation fluid to be tested by comparing the values ​​of the quenching parameter Q of the scintillation fluid corresponding to each scintillation fluid to be tested, The scintillation fluid quenching parameter Q is defined by the following formula:

2. The method for evaluating the quenching degree of a scintillation fluid according to claim 1, wherein: In step S1 , scintillation liquid to be tested is added to the liquid scintillation device respectively, and a gamma radiation source is set on the liquid scintillation device to measure the scintillation liquid to be tested respectively and obtain the corresponding liquid scintillation spectrum.

3. The method for evaluating the quenching degree of a scintillation fluid according to claim 2, wherein: The gamma radiation source is a small-volume point source.

4. The method for evaluating the quenching degree of a scintillation fluid according to claim 3, wherein: The gamma radiation source includes 137 Cs, 133 Ba or 152 Eu.

5. The method for evaluating the quenching degree of a scintillation fluid according to claim 1, wherein: The preset percentage ranges from 1% to 99%.

6. The method for evaluating the quenching degree of a scintillation fluid according to claim 1, wherein: In step S4, the larger the Q value is, the lower the quenching degree is. When Q=1, there is no quenching source.

7. The method for evaluating the quenching degree of a scintillation fluid according to claim 1, wherein: The order of steps S1, S2 and S3 can be swapped.

8. The method for evaluating the quenching degree of a scintillation fluid according to claim 1, wherein: The liquid scintillation device is a liquid scintillation bottle.

9. The method for evaluating the quenching degree of a scintillation fluid according to claim 2, wherein: The gamma radiation source is arranged at the center of the bottom of the liquid scintillator device.

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