A method for establishing low dose rate level radiation quality

Abstract

The present invention provides a method for establishing low-dose rate horizontal radiation quality, comprising: using a standard radiation source to calibrate the energy of a spectrometer to obtain a conversion relationship between the channel address of the spectrometer and the energy of the standard radiation source; calibrating an ionization chamber under the standard radiation quality to obtain a first calibration coefficient of the standard radiation quality; setting the tube voltage of an optical machine to a plurality of preset voltage values ​​respectively, and adjusting the tube current at each preset voltage value, and measuring the energy spectrum through the spectrometer at a preset distance from an optical machine outlet under the plurality of preset tube currents, measuring the dose rate through the ionization chamber, and determining additional filtering from a plurality of standby filters so that the dose rate is not greater than a preset dose rate threshold; each preset voltage value corresponds to a new radiation quality; the energy spectrum includes energy and counting rate; according to the counting rate and energy, calculating the average energy of the new radiation quality corresponding to each preset voltage value; and according to the first calibration coefficient of the standard radiation quality, obtaining a second calibration coefficient of the new radiation quality.

Description

Technical Field

[0001] The present invention relates to the field of radiation measurement technology, and in particular to a method for establishing low-dose rate level radiation quality. Background Art

[0002] The establishment of X-ray standard radiation quality provides a reference for the standardized use of X-rays. Radiation quality is a form of describing the X-ray fluence spectrum. Currently, GB12162.1, which is equivalent to ISO4037, recommends standard X-ray radiation quality including low air kerma X-ray radiation quality series (L series), narrow spectrum series (N series), wide spectrum series (W series), and high air kerma series (H series). The resolution and air kerma range of different series of radiation quality are different. These radiation qualities are in the order of increasing filtration: high air kerma series, wide spectrum series, narrow spectrum series, and low air kerma series. The dose rate values ​​of these four series of X-rays are relatively high compared to X / γ-ray energy spectrum measurement instruments, and it is difficult to cover application scenarios with dose rate levels below 10μGy / h.

[0003] At present, across the country, under the above-mentioned standard radiation quality conditions, the dose rate at 4 to 5m is not less than 5μGy / h, which brings difficulties to the measurement and traceability of low-dose rates of X-rays. Summary of the invention

[0004] The purpose of the present invention is to provide a method for establishing low dose rate level radiation quality in view of the defects of the prior art, so as to solve the problem of X-ray low dose rate measurement in the prior art.

[0005] To solve the above problems, the present invention provides a method for establishing low dose rate level radiation quality, the method comprising:

[0006] Use a standard radioactive source to calibrate the energy of the spectrometer and obtain the conversion relationship between the channel address of the spectrometer and the energy of the standard radioactive source;

[0007] Calibrate the ionization chamber under standard radiation quality to obtain the first calibration coefficient of the standard radiation quality;

[0008] The tube voltage of the optical machine is set to a plurality of preset voltage values ​​respectively, and at each preset voltage value, the tube current is adjusted, and at the plurality of preset tube currents, the energy spectrum is measured by a spectrometer at a preset distance from the optical machine outlet, the dose rate is measured by an ionization chamber, and additional filtering is determined from a plurality of standby filters so that the dose rate is not greater than a preset dose rate threshold; each preset voltage value corresponds to a new radiation mass; the energy spectrum includes energy and count rate;

[0009] Calculating the average energy of new radiation corresponding to each preset voltage value according to the counting rate and the energy;

[0010] According to the first calibration coefficient of the standard radiation quality, a second calibration coefficient of the new radiation quality is obtained.

[0011] In a possible implementation, the method further includes:

[0012] Identify multiple filters to be used.

[0013] In a possible implementation, determining a plurality of unused filters specifically includes:

[0014] Measuring the thickness values ​​of a first number of positions on each of the two sides of each filter plate to obtain a second number of thickness values; the second number is twice the first number;

[0015] Calculate the average value and standard deviation of the second number of thickness values; when the standard deviation is less than or equal to a preset ratio threshold, use the average value as the thickness of the filter and use the filter as a standby filter; when the standard deviation is greater than the preset ratio threshold, discard the filter.

[0016] In a possible implementation, the energy calibration of the spectrometer using a standard radiation source to obtain the conversion relationship between the channel address of the spectrometer and the energy of the standard radiation source specifically includes:

[0017] The full energy peak position of the standard radioactive source is matched with the channel address of the energy spectrum to obtain the conversion relationship between the channel address and energy.

[0018] In a possible implementation, the ionization chamber calibration under standard radiation quality to obtain a first calibration coefficient of the standard radiation quality specifically includes:

[0019] A 10L ball cavity ionization chamber was placed at a preset distance from the optical machine and counted by an electrometer;

[0020] Under multiple standard radiation quality conditions, the ionization current is read by an electrometer, and the ionization current is matched with the standard dose rate of each standard radiation quality to obtain the first calibration coefficient of the 10L spherical cavity ionization chamber under each standard radiation quality.

[0021] In a possible implementation, calculating the average energy of the new radiation corresponding to each preset voltage value according to the counting rate and the energy specifically includes:

[0022] According to the formula Calculate the average energy of each new radiant mass;

[0023] in, is the average energy; E is the energy in the energy spectrum distribution, dE is the energy width, n is the count rate in the energy spectrum of the detection that falls within the range of E±dE; i is the channel address number of the energy division in the detector energy spectrum, and m is the total number of channels. i is the central energy of the detector energy spectrum corresponding to channel address i, n i is the count rate that falls into channel address i in the detector energy spectrum.

[0024] In a possible implementation, obtaining the second calibration coefficient of the new radiation quality according to the first calibration coefficient of the standard radiation quality specifically includes:

[0025] According to the formula Calculate the second scale factor;

[0026] Among them, E0 and E1 are the average energies of the standard radiation masses adjacent to the new radiation mass, c0 and c1 are the first calibration coefficients of the two standard radiation masses adjacent to the new radiation mass, E i is the average energy of the new radiation mass, and c is the second calibration coefficient of the new radiation mass.

[0027] In a possible implementation, the plurality of preset voltage values ​​include 70 KV, 90 KV, 100 KV, 125 KV and 140 KV, and the preset distance is 4 m.

[0028] In a possible implementation, the preset dose rate threshold is 10 μGy / h.

[0029] The method for establishing low-dose-rate level radiation quality provided by the embodiment of the present invention uses energy scale and ionization chamber scale to realize the initial measurement of energy spectrum and dose rate at a specific position using a spectrometer and a dosimeter, and calculates its average energy based on the energy spectrum, and then combines the interpolation algorithm to realize the accurate measurement of the radiation quality dose rate by the ionization chamber, thereby determining the low-dose-rate level radiation quality, and the radiation quality energy spectrum, dose rate level, etc. determined thereby are more accurate. Further, the thickness of the additional filtering Al, Sn, and Cu sheets is adjusted so that the dose rate at 4m away from the optical machine is covered within the set dose rate range of ≤10μGy / h. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 One of the flow charts of the method for establishing low dose rate level radiation quality provided by an embodiment of the present invention;

[0031] Figure 2 A second flow chart of a method for establishing low dose rate level radiation quality provided by an embodiment of the present invention;

[0032] Figure 3A One of the 70KV ray standard energy spectra provided in the embodiment of the present invention;

[0033] Figure 3B The second 70KV ray standard energy spectrum diagram provided by the embodiment of the present invention;

[0034] Figure 4A One of the 90KV ray standard energy spectra provided in the embodiment of the present invention;

[0035] Figure 4B The second 90KV ray standard energy spectrum diagram provided by the embodiment of the present invention;

[0036] Figure 5A One of the 100KV ray standard energy spectra provided in the embodiment of the present invention;

[0037] Figure 5B The second 100KV ray standard energy spectrum diagram provided by the embodiment of the present invention;

[0038] Fig. 6A One of the 125KV ray standard energy spectra provided in the embodiment of the present invention;

[0039] Figure 6B The second 125KV ray standard energy spectrum diagram provided by the embodiment of the present invention;

[0040] Fig. 7A One of the 140KV ray standard energy spectra provided in the embodiment of the present invention;

[0041] Figure 7B This is the second 140KV ray standard energy spectrum diagram provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0043] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The technical solution of the present invention is further described in detail below through the drawings and embodiments.

[0044] Figure 1 One of the flow charts of the method for establishing low dose rate level radiation quality provided by an embodiment of the present invention; Figure 1 As shown, the method comprises the following steps:

[0045] Step 110, using a standard radiation source to calibrate the energy of the spectrometer, and obtaining a conversion relationship between the channel address of the spectrometer and the energy of the standard radiation source;

[0046] Among them, the full energy peak position of the standard radioactive source can be matched with the channel address of the energy spectrum to obtain the conversion relationship between the channel address and the energy. When calibrating the spectrometer, in order to improve the accuracy of the subsequent conversion relationship, no less than five energy points are used for calibration operations. At each energy point, a set of channel addresses and energies can be obtained. Based on multiple sets of channel addresses and energies, the calibration coefficient between the two can be obtained. The calibration coefficient can be expressed as a linear relationship.

[0047] Specifically, by way of example and not limitation, the present application can use a high-purity germanium spectrometer to perform spectrum sampling on a standard radioactive source. Since the full-energy peak energy of the standard radioactive source is known, the full-energy peak energy of the standard radioactive source is matched with the channel address of the energy spectrum measured by the high-purity germanium spectrometer to obtain the corresponding conversion relationship between the channel address and the energy, that is, the calibration coefficient of the channel address and the energy:

[0048] Energy = a channel + b (1)

[0049] Among them, Energy represents energy, channel represents channel address, a represents the first parameter in the conversion relationship, and b represents the second parameter in the conversion relationship.

[0050] It should be noted that the present application uses a high-purity germanium spectrometer for energy spectrum measurement, and other spectrometer-type detectors may be used as substitutes for energy spectrum measurement in specific applications. Other spectrometer-type detectors include but are not limited to semiconductor detectors, such as gold silicon surface barrier detectors, scintillator detectors, such as sodium iodide detectors, lanthanum bromide detectors, etc.

[0051] In an optional implementation, if Figure 2 As shown, before executing step 110, step 210 is also included.

[0052] Step 210, determining a plurality of filters to be used.

[0053] Specifically, the thickness values ​​of a first number of positions of each surface of the two surfaces of each filter plate are measured to obtain a second number of thickness values; the second number is twice the first number;

[0054] Calculate the average value and standard deviation of the second number of thickness values. When the standard deviation is less than or equal to the preset ratio threshold, use the average value as the thickness of the filter and use the filter as a standby filter. When the standard deviation is greater than the preset ratio threshold, remove the filter.

[0055] For example, the filter can be made of metals such as Cu, Al, and Sn. When measuring thickness, five different positions are measured on each surface. A total of 10 thicknesses can be obtained on the two surfaces, which are recorded as d1, d2, d3, ..., d10, and the average value is taken. As the filter thickness, find the average value of 10 thicknesses When the standard deviation σ of the 10 thickness values ​​is higher than a preset ratio threshold, such as 5%, the filter sheet is removed.

[0056] The formula for calculating the mean value is shown in formula (2), and the formula for calculating the standard deviation is shown in formula (3):

[0057]

[0058]

[0059] Wherein, n is the number of thicknesses measured.

[0060] It is understandable that Cu, Al, and Sn metal sheets are used for X-ray radiation quality construction in the present application. Other materials may be used as substitutes in specific applications, such as lead sheets, graphite sheets, etc., and the present application does not limit this.

[0061] Step 120, calibrating the ionization chamber under standard radiation quality to obtain a first calibration coefficient of the standard radiation quality;

[0062] Among them, this application will take the 10L spherical cavity ionization chamber as an example to illustrate the ionization chamber calibration. It is understandable that other ionization chambers can be used to replace dose rate measurement in specific applications. Other ionization chambers include but are not limited to other dosimeters, such as high-pressure ionization chambers, scintillator dose rate meters, semiconductor dose rate meters, thermoluminescence dosimeters, photoluminescence dosimeters, etc. The radiation field used for ionization chamber calibration in this application is the L series standard radiation field. In specific applications, other series of standard radiation fields can be used to replace the dose meter calibration, and this application is not limited to this.

[0063] Specifically, the ionization chamber can be calibrated under standard low air kerma (L series) radiation quality. A 10L spherical cavity ionization chamber is placed 4m away from the optical machine and read by a UNIDOS electrometer. Under radiation quality conditions where the tube voltage is L55, L70, L100, L125, L170, L210, and L240, the ionization current I is read out by the electrometer, and the ionization current value I is matched with the standard dose rate value, and the first calibration coefficient c of the 10L spherical cavity ionization chamber is obtained according to formula (4).

[0064]

[0065] Where: c represents the first scale coefficient of the ionization chamber, I represents the ionization current, Indicates the dose rate.

[0066] Specifically, the calibration coefficients are calculated in turn under different L-series standard radiation qualities. Since the average energy of each standard radiation quality is known, the corresponding relationship between energy and calibration coefficient c can be obtained, as shown in Table 1. Table 1 shows the calibration coefficients of the 10L spherical cavity ionization chamber under L-series X-ray radiation quality. In the subsequent dose rate measurement, the corresponding ionization chamber calibration coefficient is obtained according to the energy linear interpolation.

[0067] Tube voltage / kV Average energy / keV Scale factor / μGy·h-1·pA-1 55 48 12.2 70 61 11.8 100 87 11.5 125 109 11.8 170 149 11.8 210 185 11.8 240 211 11.7

[0068] Table 1

[0069] Step 130, respectively setting the tube voltage of the optical machine to a plurality of preset voltage values, and adjusting the tube current at each preset voltage value, and measuring the energy spectrum by a spectrometer at a preset distance from the optical machine outlet at a plurality of preset tube currents, measuring the dose rate by an ionization chamber, and determining additional filtering from a plurality of standby filters so that the dose rate is not greater than a preset dose rate threshold; each preset voltage value corresponds to a new radiation quality; the energy spectrum includes energy and count rate;

[0070] Specifically, by way of example and not limitation, the new radiation quality may be 70KV, 90KV, 100KV, 125KV and 140KV. Now, taking the above-mentioned radiation qualities as examples, step 130 of the present application is described. The preset distance is an empirical value from multiple experiments. For example, the present application may take the preset distance as 4m. In specific applications, if the actual conditions cannot be met, it may be performed at other distances, and the present application does not limit this. Multiple preset tube currents may be 2μA, 5μA, 10μA and 20μA. The preset dose rate threshold may be 10μGy / h.

[0071] First, the construction of 70kV new radiation quality

[0072] (1) Preliminary determination of dose rate range

[0073] The tube voltage of the optical machine was set to 70 kV, and the energy spectrum and dose rate were acquired at a distance of 4 m from the optical machine outlet under different tube current conditions. The energy spectrum was acquired using a high-purity germanium spectrometer, and its energy scale used the scale factor of step 110. The dose rate was acquired using a 10L spherical cavity ionization chamber, and its scale factor used the scale factor obtained in step 120.

[0074] By adding a filter at the exit of the optical machine and adjusting the thickness of the filter, the dose rate value measured by the cavity ionization chamber at 4m can cover the range of ≤10μGy / h. An example of additional filtration obtained according to this method is: 3.488mmCu+2.022mmAl.

[0075] (2) Measurement of radiation quality

[0076] Energy spectrum measurement is carried out under this radiation quality. An example of a standard energy spectrum diagram of 70kV at 4m is as follows: Figure 3A and Figure 3B As shown, in Figure 3A In the figure, the corresponding currents of the four curves increase from bottom to top, namely 2μA, 5μA, 10μA and 20μA. Figure 3B It is the energy spectrum after normalizing the energy.

[0077] Second, the construction of 90kV new radiation quality

[0078] (1) Determination of dose rate range

[0079] The tube voltage of the optical machine is set to 90 kV, and the dose rate is measured at 4 m from the optical machine outlet under different tube current conditions. The dose rate is obtained through a 10L spherical cavity ionization chamber, and its calibration coefficient uses the calibration coefficient obtained in step 120.

[0080] By placing a filter at the exit of the optical machine and adjusting the thickness of the additional filter, the dose rate value measured in the cavity ionization chamber at 4m covers the range of ≤10μGy / h. An example of 90kV additional filtering obtained according to this method is: 6.77mmCu+3.02mmAl.

[0081] (2) Determination of radiation quality

[0082] Under this radiation quality, a high-purity germanium spectrometer is used to measure the energy spectrum, and its energy scale adopts the scale factor of step 110. The 90 kV standard energy spectrum is obtained at 4 m as follows Figure 4A and 4B As shown. Figure 4A In the figure, the corresponding currents of the four curves increase from bottom to top, namely 2μA, 5μA, 10μA and 20μA. Figure 4B It is the energy spectrum after normalizing the energy.

[0083] Third, the construction of 100kV new radiation quality

[0084] (1) Determination of dose rate range

[0085] The tube voltage of the optical machine is set to 100 kV, and the dose rate is measured at 4 m from the optical machine outlet under different tube current conditions. The dose rate is obtained through a 10L spherical cavity ionization chamber, and its calibration coefficient uses the calibration coefficient obtained in step 120.

[0086] By placing copper, aluminum, and zinc filters at the exit of the optical machine, and adjusting the thickness of the additional filters, the dose rate value measured in the cavity ionization chamber at 4m covers the range of ≤10μGy / h. An example of 100kV additional filtration obtained according to this method is: 2.40mmSn+2.05mmCu+3.02mmAl.

[0087] (2) Determination of radiation quality

[0088] Under this radiation quality, a high-purity germanium spectrometer is used to measure the energy spectrum, and its energy scale adopts the scale factor of step 110. The 100 kV standard energy spectrum is obtained at 4 meters as follows: Figure 5A and 5B As shown. Figure 5A In the figure, the corresponding currents of the four curves increase from the lower network to 2μA, 5μA, 10μA and 20μA respectively. Figure 5B It is the energy spectrum after normalizing the energy.

[0089] Fourth, the construction of 125kV new radiation quality

[0090] (1) Determination of dose rate range

[0091] The tube voltage of the optical machine is set to 125 kV, and the dose rate is measured at 4 m from the optical machine outlet under different tube current conditions. The dose rate is obtained through a 10L spherical cavity ionization chamber, and its calibration coefficient uses the calibration coefficient obtained in step 120.

[0092] By placing copper, aluminum, and zinc filters at the exit of the optical machine, and adjusting the thickness of the additional filters, the dose rate value measured in the cavity ionization chamber at 4m covers the range of ≤10μGy / h. An example of 125kV additional filtration obtained according to this method is: 2.40mmSn+2.05mmCu+3.02mmAl.

[0093] (2) Determination of radiation quality

[0094] Under this radiation quality, a high-purity germanium spectrometer is used to measure the energy spectrum, and its energy scale adopts the scale factor of step 110. The 125 kV standard energy spectrum is obtained at 4 m as follows Fig. 6A and 6B As shown. Fig. 6A In the figure, the corresponding currents of the four curves increase from the lower network to 2μA, 5μA, 10μA and 20μA respectively. Figure 6B It is the energy spectrum after normalizing the energy.

[0095] Fifth, 140kV new radiation quality construction

[0096] (1) Determination of dose rate range

[0097] The tube voltage of the optical machine is set to 140 kV, and the dose rate is measured at 4 m from the optical machine outlet under different tube current conditions. The dose rate is obtained through a 10L spherical cavity ionization chamber, and its calibration coefficient uses the calibration coefficient obtained in step 120.

[0098] By placing copper, aluminum, and zinc filters at the exit of the optical machine, and adjusting the thickness of the additional filters, the dose rate value measured in the cavity ionization chamber at 4m covers the range of ≤10μGy / h. An example of 140kV additional filtration obtained according to this method is: 8.53mmSn+2.55mmCu+3.02mmAl.

[0099] (2) Determination of radiation quality

[0100] Under this radiation quality, a high-purity germanium spectrometer is used to measure the energy spectrum, and its energy scale adopts the scale factor of step 110. The 140 kV standard energy spectrum is obtained at 4 m as follows Fig. 7A and 7B As shown. Fig. 7A In the figure, the corresponding currents of the four curves increase from the lower network to 2μA, 5μA, 10μA and 20μA respectively. Figure 7B It is the energy spectrum after normalizing the energy.

[0101] Thus, after the construction of the first to fifth types of radiation quality, the tube voltages are 70kV, 90kV, 100kV, 125kV, and 140kV, and the additional filtering is each X-ray standard energy spectrum example under the above-listed examples. Subsequently, the (70kV~140kV) X-ray radiation quality is constructed, and the dose rate value at 4m is lower than 1μGy / h, thereby achieving full coverage of the dose rate range below 10μGy / h, meeting the application of low dose rate measurement and metrological traceability in the whole society.

[0102] Step 140, calculating the average energy of the new radiation corresponding to each preset voltage value according to the counting rate and the energy;

[0103] Through steps 110-130, an example of low-dose rate radiation quality under tube voltages of 70 kV, 90 kV, 100 kV, 125 kV, and 140 kV is obtained. Here, the average energy of the constructed low-dose rate radiation quality example is solved, and the calculation formula is shown in (5).

[0104]

[0105] in: is the average energy; φ is the ray fluence spectrum, and E is the energy in the energy spectrum. The measured energy spectrum is used to calculate the average energy, and the calculation formula is shown in (6).

[0106]

[0107] in, is the average energy; E is the energy in the energy spectrum distribution, dE is the energy width, n is the count rate in the energy spectrum of the detection that falls within the range of E±dE; i is the channel address number of the energy division in the detector energy spectrum, and m is the total number of channels. i is the central energy of the detector energy spectrum corresponding to channel address i, n i is the count rate that falls into channel address i in the detector energy spectrum.

[0108] The calculation results of the average energy of the new radiation mass are shown in Table 2.

[0109] Tube voltage / kV Average energy / keV 70 52 90 69 100 78 125 97 140 108

[0110] Table 2

[0111] Step 150, obtaining a second calibration coefficient of the new radiation quality according to the first calibration coefficient of the standard radiation quality.

[0112] In step 120, the ionization chamber is calibrated by the standard L-series X-ray radiation field. Here, the calculation of the ionization chamber calibration coefficient under the new X-ray radiation quality is realized by linear interpolation of the first calibration coefficient of step 120. The linear interpolation formula is shown in formula (7).

[0113]

[0114] Among them, the average energy at the endpoints is E0 and E1 respectively, and the first scale coefficients at the corresponding endpoints are c0 and c1 respectively. The energy E is required. i The scale factor c i .

[0115] For example, if the new radiation quality is 90KV, c0 can be taken as the first scale factor of the 70KV standard radiation quality, which is 11.8 from Table 1, E0 is the average energy of the 70KV standard radiation quality, which is 61 from Table 1, c1 is the first scale factor of the 100KV standard radiation quality, which is 11.5 from Table 1, E1 is the average energy of the 100KV standard radiation quality, which is 87 from Table 1, and E i is the average energy of the 90KV new radiation quality. From Table 2, we can get that it is 69. Therefore, according to formula (7), we can get that the scale factor of the 90KV new radiation quality is 11.7.

[0116] Finally, additional filtering of low dose rate X-ray radiation quality, average energy, and ionization chamber calibration factor can be considered, and the corresponding results are shown in Table 3.

[0117] Table 3 New low dose rate X-ray radiation quality examples are shown in Table 3.

[0118]

[0119] Table 3

[0120] The method for establishing low-dose-rate level radiation quality provided by the embodiment of the present invention uses energy scale and ionization chamber scale to realize the initial measurement of energy spectrum and dose rate at a specific position using a spectrometer and a dosimeter, and calculates its average energy based on the energy spectrum, and then combines the interpolation algorithm to realize the accurate measurement of the radiation quality dose rate by the ionization chamber, thereby determining the low-dose-rate level radiation quality, and the radiation quality energy spectrum, dose rate level, etc. determined thereby are more accurate. Further, the thickness of the additional filtering Al, Sn, and Cu sheets is adjusted so that the dose rate at 4m away from the optical machine is covered within the set dose rate range of ≤10μGy / h.

[0121] The professionals should further realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to the function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0122] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented using hardware, a software module executed by a terminal, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0123] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for establishing low dose rate level radiation quality, characterized in that, The method comprises: Use a standard radioactive source to calibrate the energy of the spectrometer and obtain the conversion relationship between the channel address of the spectrometer and the energy of the standard radioactive source; Calibrate the ionization chamber under standard radiation quality to obtain the first calibration coefficient of the standard radiation quality; The tube voltage of the optical machine is set to a plurality of preset voltage values ​​respectively, and at each preset voltage value, the tube current is adjusted, and at the plurality of preset tube currents, the energy spectrum is measured by a spectrometer at a preset distance from the optical machine outlet, the dose rate is measured by an ionization chamber, and additional filtering is determined from a plurality of standby filters so that the dose rate is not greater than a preset dose rate threshold; each preset voltage value corresponds to a new radiation mass; the energy spectrum includes energy and count rate; Calculating the average energy of new radiation corresponding to each preset voltage value according to the counting rate and the energy; According to the first calibration coefficient of the standard radiation quality, a second calibration coefficient of the new radiation quality is obtained.

2. The method according to claim 1, characterized in that The method also includes: Identify multiple filters to be used.

3. The method according to claim 2, characterized in that The determining of a plurality of filter sheets to be used specifically comprises: Measuring the thickness values ​​of a first number of positions on each of the two sides of each filter plate to obtain a second number of thickness values; the second number is twice the first number; Calculate the average value and standard deviation of the second number of thickness values; when the standard deviation is less than or equal to a preset ratio threshold, use the average value as the thickness of the filter and use the filter as a standby filter; when the standard deviation is greater than the preset ratio threshold, discard the filter.

4. The method according to claim 1, characterized in that: The energy calibration of the spectrometer using a standard radiation source to obtain the conversion relationship between the channel address of the spectrometer and the energy of the standard radiation source specifically includes: The full energy peak position of the standard radioactive source is matched with the channel address of the energy spectrum to obtain the conversion relationship between the channel address and energy.

5. The method according to claim 1, characterized in that The ionization chamber calibration under standard radiation quality to obtain the first calibration coefficient of the standard radiation quality specifically includes: A 10L ball cavity ionization chamber was placed at a preset distance from the optical machine and counted by an electrometer; Under multiple standard radiation quality conditions, the ionization current is read by an electrometer, and the ionization current is matched with the standard dose rate of each standard radiation quality to obtain the first calibration coefficient of the 10L spherical cavity ionization chamber under each standard radiation quality.

6. The method according to claim 1, characterized in that Calculating the average energy of the new radiation corresponding to each preset voltage value according to the counting rate and the energy specifically includes: According to the formula Calculate the average energy of each new radiant mass; in, is the average energy; E is the energy in the energy spectrum distribution, dE is the energy width, n is the count rate in the energy spectrum of the detection falling within the range of E±dE; i is the channel address number of the energy division in the detector energy spectrum, m is the total number of channels, E i is the central energy of the detector energy spectrum corresponding to channel address i, n i is the count rate that falls into channel address i in the detector energy spectrum.

7. The method according to claim 1, characterized in that The step of obtaining the second calibration coefficient of the new radiation quality according to the first calibration coefficient of the standard radiation quality specifically includes: According to the formula Calculate the second scale factor; Among them, E0 and E1 are the average energies of the standard radiation masses adjacent to the new radiation mass, c0 and c1 are the first calibration coefficients of the two standard radiation masses adjacent to the new radiation mass, E i is the average energy of the new radiation mass, and c is the second calibration coefficient of the new radiation mass.

8. The method according to claim 1, characterized in that Multiple preset voltage values ​​include 70KV, 90KV, 100KV, 125KV and 140KV, and the preset distance is 4m.

9. The method according to claim 1, characterized in that: The preset dose rate threshold is 10 μGy / h.

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