KR102224603B1 - Radiation detector and method for controlling the same - Google Patents

Abstract

The present invention aims to provide a radiation detector and a control method thereof, which are able to automatically correct an output of the radiation detector in accordance with changes in the background radiation, and to maintain a good detection accuracy even when there are changes in the external environment. According to the present invention, the control method of the radiation detector, in a control method of the radiation detector for detecting radiation generated from radioactive elements, comprises: a step of determining whether the radiation detector is in an operation mode; a step of, when the radiation detector is not in the operation mode, measuring the background radiation; a step of calculating the energy weighting factor (Cw) by applying each energy as a weighted value to each channel for the energy spectrum of the measured background radiation, and generating a background radiation energy weighting spectrum with the X-axis as the energy value and the Y-axis as the energy weighting factor (Cw); a step of calculating the peak position (Pb) of the ^40K from the background radiation energy weighting spectrum; a step of comparing the peak position (Pb) of the ^40K with the preset reference peak position range; and a step of, when the peak position (Pb) of the ^40K has exceeded the preset reference peak position range, correcting the output of the radiation detector. The energy weighting factor (Cw) satisfies a following formula: Cw = (C x E)^n x E^m (C: Photon counting collected for each channel, E: Energy of each channel, n: Natural number of 2 or above, m: Natural number of 1 or above).

Description

Radiation detector and its control method {RADIATION DETECTOR AND METHOD FOR CONTROLLING THE SAME}

The present invention relates to a radiation detector, and more particularly, to a radiation detector capable of maintaining good detection accuracy even with a change in external environment by automatically correcting an output according to a change in background radiation, and a control method thereof.

An unstable nucleus undergoes several nuclear decays to become a stable nucleus, and at this time, it emits alpha rays, beta rays, and gamma rays of specific energy.

The radiation detector is a device capable of discriminating a unique radionuclide constituting the material by measuring and analyzing the energy of radiation generated from a material containing an unknown radionuclide.

The scintillator used in the radiation detector has the property of emitting light when it receives energy. By measuring the amount of light generated by the radiation, it is possible to check the energy of the incident radiation. The higher the energy the scintillator receives, the more light it generates.

Radiation detectors include a detector using a plastic scintillator and a detector using an inorganic scintillator.

In the case of a scintillation detector using an inorganic scintillator (e.g., NaI(TI) or CsI(TI)), the photoelectric effect that absorbs all the energy of gamma rays is high and the energy resolution is excellent, so the energy of the photo peak is reduced. As a basis, radionuclides can be easily analyzed. However, it has the disadvantage of being expensive.

Radionuclide detectors using plastic scintillators (or other types of organic scintillators) rarely produce photoelectric effects and have relatively low energy resolution. Conventionally, only the amount of radiation delivered to the detector is measured using a gross counting method, or in a specific field, several energy regions corresponding to target nuclides are set as the region of interest, and the amount of radiation measured in each region Was evaluated to infer the nuclide. In other words, rather than analyzing the nuclides themselves, a group containing radionuclides with similar energy was inferred.

The conventional radiation detector uses an analysis algorithm in which a Compton edge or a specific point is emphasized in a peak shape by weighting the count value of each channel of the measured energy spectrum and the energy corresponding to each channel.

However, in an environment where measurement efficiency is low, the energy weighted spectrum according to the conventional analysis algorithm may change in the shape of the spectrum depending on whether or not background radiation is canceled. In particular, since the radiation detector for vehicle search is operated in an external environment, it is very important to consider the external environment such as a change in background radiation when applying an analysis algorithm.

Registered Patent Publication No. 1680067 (2016. 11.

The present invention was devised in consideration of the above points, and automatically corrects the output of the radiation detector according to the change of the background radiation analyzed through an additional algorithm that further emphasizes the peak value of the existing energy weighted spectrum. An object of the present invention is to provide a radiation detector capable of maintaining good detection accuracy even with changes and a control method thereof.

The control method of a radiation detector according to the present invention for solving the above object is, in the control method of a radiation detector for detecting radiation generated from a radioactive element, (a) determining whether the radiation detector is in an operation mode. step; (b) measuring background radiation when the radiation detector is not in an operation mode; (c) Background radiation energy with an energy weighting factor (Cw) being calculated by applying each energy as a weight for each channel to the energy spectrum of the measured background radiation, and the x-axis as the energy value and the y-axis as the energy weighting factor (Cw). Generating a weighted spectrum; (d) calculating a peak position (Pb) ^{of 40} K from the background radiation energy weighted spectrum; (e) comparing the reference peak position range of the peak position (Pb) of the predetermined ⁴⁰ K; And (f) ^{correcting the output of the radiation detector when the 40} K peak position Pb is out of a preset reference peak position range, wherein the energy weighting factor Cw is calculated by the following equation: Satisfies.

Cw = (C x E) ⁿ x E ^m

(C: photon count collected in each channel, E: energy of each channel, n: natural number greater than or equal to 2, m: natural number greater than or equal to 1)

In the above formula, both constants n and m are preferably 3 or less.

The method for controlling a radiation detector according to the present invention includes the steps of: (g) receiving energy generated from a radioactive element when the radiation detector is in an operation mode after the step (a); (h) generating an energy weighted spectrum with an x-axis as an energy value and a y-axis as the energy weighting factor (Cw) by applying the energy weighting factor (Cw) to the spectrum of the input energy; And (i) detecting a nuclide of the radioactive element based on the energy weighting spectrum, and setting an energy value corresponding to the peak value of the energy weighting factor Cw of the radioactive element to the Compton edge of the preset radioactive elements. It may include; comparing the energy values and detecting the nuclide of the radioactive element.

In the control method of a radiation detector according to the present invention, two or more energy weighting factors (Cw) are calculated by differently from a constant n and m, and the energy weighting spectrum is 2 for the two or more energy weighting factors (Cw). At least two are generated, and in step (i), an energy value corresponding to a peak value of the two or more energy weighting coefficients (Cw) for the radioactive element in each of the two or more energy weighted spectra is the two or more energy Nuclides of the radioactive element may be detected by comparing each of the energy values of the Compton edge of the radioactive elements preset with respect to the weighting factor Cw.

In the method for controlling a radiation detector according to the present invention, in the step (f), the output of the radiation detector may be increased or decreased in proportion to an absolute size where ^{the 40 K peak position Pb is out of a preset reference peak position range.} have.

On the other hand, in the radiation detector according to the present invention for solving the above object, in a radiation detector for detecting radiation emitted from a radioactive element, background radiation and radiation emitted from the radioactive element are input and converted into an electric signal. An input unit; A signal processing unit processing an electric signal received from the input unit; An energy spectrum for background radiation and an energy spectrum for radiation of the radioactive element are respectively generated from the signal received from the signal processing unit, and each energy is applied as a weight for each channel to the generated energy spectrum, and an energy weighting factor (Cw ) Is calculated, and an energy weighted spectrum is generated with the x-axis as the energy value and the y-axis as the energy weighting factor (Cw) for the background radiation, and the background radiation energy weighted spectrum is generated, and the x-axis for the radiation of the radioactive element An energy weighted spectrum with the y-axis as the energy weighting factor (Cw) is generated as an energy value, and the energy value corresponding to the peak value of the energy weighting factor (Cw) for the radioactive element is determined by the Compton edge of the radioactive elements. A control unit for detecting a nuclide of the radioactive element by comparing with energy values, wherein the control unit calculates a peak position (Pb) ^{of 40 K from the background radiation energy weighted spectrum, and the peak position (Pb) of 40} K ) Is compared with a preset reference peak position range, and when the ⁴⁰ K peak position (Pb) is out of a preset reference peak position range, the output of the radiation detector is corrected, and the energy weighting factor (Cw) is: Satisfies the formula of

Cw = (C x E) ⁿ x E ^m

(C: photon count collected in each channel, E: energy of each channel, n: natural number greater than or equal to 2, m: natural number greater than or equal to 1)

The input unit may include a scintillator for converting incident radiation into visible light, and a photomultiplier tube connected to the scintillator to focus visible light generated from the scintillator and convert it into an electrical signal.

The control unit calculates two or more of the energy weighting coefficients Cw differently from a constant n and m, and generates two or more energy weighting spectra for the two or more energy weighting coefficients Cw, and the 2 Compton of the radioactive elements preset for the at least two energy weighting coefficients (Cw) is an energy value corresponding to the peak value of the at least two energy weighting coefficients (Cw) for the radioactive element in each of the at least two energy weighting spectra Each of the energy values of the edge may be compared to detect the nuclide of the radioactive element.

Wherein the control unit has a ⁴⁰ K of the peak position (Pb) it can be proportional to the absolute magnitude outside the predetermined range based on the peak position to increase or decrease the output of the radiation detector.

According to the present invention, a background radiation energy weighted spectrum is generated through an additional algorithm that further emphasizes the peak value of the existing energy weighted spectrum, and the peak value of ⁴⁰ K present in this background radiation energy weighted spectrum is identified, and this information is used. Thus, it can automatically calibrate the output of the radiation detector. Accordingly, the output of the radiation detector can be stabilized regardless of changes in the external environment, and good detection accuracy can be maintained even with changes in the external environment.

In addition, according to the present invention, by applying an additional algorithm that further emphasizes the peak value of the existing energy weighted spectrum, it is possible to increase the accuracy of radiation detection under conditions of low measurement efficiency in which radioactive elements move, and resources required for secondary search It is possible to detect radioactive materials while maintaining a smooth logistics flow in ports or border areas.

1 schematically shows a radiation detector according to an embodiment of the present invention.
2 shows an example of using a radiation detector according to an embodiment of the present invention.
3 schematically shows a radiation detector according to another embodiment of the present invention.
4 shows an example of using a radiation detector according to another embodiment of the present invention.
5 is a flowchart schematically showing a method of controlling a radiation detector according to an embodiment of the present invention.
6 and 7 show energy weighted spectra of ⁴⁰ K analyzed using a conventional method and a control method of a radiation detector according to an exemplary embodiment of the present invention for an experimental example.
8 shows the energy spectrum of ⁶⁰ Co and ⁴⁰ K according to another experimental example.
9 shows energy weighted spectra of ⁶⁰ Co and ⁴⁰ K analyzed using a conventional method for the experimental example of FIG. 8.
10 and 11 show energy weighted spectra of ⁶⁰ Co and ⁴⁰ K, respectively, analyzed using the control method of a radiation detector according to an embodiment of the present invention for the experimental example of FIG. 8.
12 shows the energy spectrum of ¹³⁷ Cs and ⁶⁰ Co according to another experimental example.
13 shows energy weighted spectra of ¹³⁷ Cs and ⁶⁰ Co analyzed using a conventional method for the experimental example of FIG. 12.
14 and 15 show energy weighted spectra of ¹³⁷ Cs and ⁶⁰ Co, respectively, analyzed using the control method of a radiation detector according to an embodiment of the present invention for the experimental example of FIG. 12.

Hereinafter, a radiation detector and a control method thereof according to the present invention will be described in detail with reference to the drawings.

1 schematically shows a radiation detector according to an embodiment of the present invention, and FIG. 2 shows an example of using a radiation detector according to an embodiment of the present invention.

As shown in the drawing, the radiation detector 100 according to an embodiment of the present invention includes an input unit 110 receiving background radiation and radiation emitted from a radioactive element, and processing an electrical signal received from the input unit 110. A signal processing unit 120 and a control unit 130 for detecting radiation by analyzing a signal received from the signal processing unit 120 are included. The controller 130 may detect radiation emitted from a radioactive element in an operation mode, and detect background radiation in a standby mode to correct an output according to a change in an external environment. ^{The radiation detector 100 checks the peak value of 40} K present in the background radiation and corrects the output in real time, thereby automatically stabilizing without the need for a separate correction source.

The input unit 110 receives background radiation and radiation generated from a radioactive element. The input unit 110 includes a scintillator 111 and a photomultiplier tube 112. The scintillator 111 converts the incident radiation into visible light, and the photomultiplier tube 112 is connected to the scintillator 111 to focus visible light generated from the scintillator 111 to convert it into an electrical signal. The scintillator 111 and the photomultiplier tube 112 may be arranged in parallel to increase the detection area for incident radiation and increase the detection capability of the radiation detector 100.

The signal processing unit 120 may remove noise by summing electrical signals received from the plurality of photomultiplier tubes 112, amplify the noise-removed signal, and provide the amplified signal to the control unit 130.

The control unit 130 is connected to the signal processing unit 120 and processes a signal received from the signal processing unit 120 to detect radiation, and automatically corrects the output of the radiation detector 100 to stabilize the radiation detector 100. That is, the control unit 130 generates an energy spectrum of incident radiation from a signal received from the signal processing unit 120 and calculates an energy weighting factor Cw by applying each energy as a weight for each channel to the energy spectrum. And, based on the weighted energy-weighted spectrum, the radioactive element's nuclides are detected, and the background radiation energy-weighted spectrum, which is weighted, is used to determine the ⁴⁰ K peak value present in the background radiation. Accordingly, the output of the radiation detector 100 is automatically corrected.

Here, the energy spectrum of radiation can be represented by a graph in which the x-axis is an energy value and the y-axis is a photon count. In addition, the energy weighted spectrum and the background radiation energy weighted spectrum may be represented by graphs in which the x-axis is an energy value and the y-axis is an energy weighting factor (Cw).

The controller 130 may determine the peak value of the energy weighted spectrum, and compare the energy of the corresponding peak value with the energies of the Compton edge of the preset radioactive elements to determine the nuclide of the radioactive element. In addition, the control unit 130 calculates a peak position (Pb) ^{of 40} K from the background radiation energy weighted spectrum, compares ^{the peak position (Pb) of 40} K with a preset reference peak position range, and the peak position of ^{40 K (} When Pb) is out of the preset reference peak position range, the output of the radiation detector 100 may be corrected.

When the gamma ray emitted from the radioactive material enters the scintillator 111, the gamma ray collides with the electrons of the scintillator 111 to cause a scattering reaction, and the control unit 130 generates a radiation energy spectrum by the scattering reaction. In the energy spectrum generated by the controller 130, a Compton edge showing a peak value appears. The energy region in which the Compton edge appears in the energy spectrum is a unique property of each different material according to the type of each radioactive material. Therefore, the Compton edge area of the radiation emitted from the radioactive element can be determined by using the intrinsic properties of the radioactive material. And the type of radioactive material can be determined from this.

Although not shown in the drawings, the radiation detector 100 according to an embodiment of the present invention may further include a memory and an output unit. The memory may store energy values of a Compton edge of preset radioactive elements or data on a reference peak position range of ^{40 K.} The control unit 130 may determine the radioactive element corresponding to the energy of the peak value measured based on the energy values of the Compton edge of radioactive elements stored in the memory, ⁴⁰ K stored in the peak position of the analyzed ⁴⁰ K in memory Can be compared with the reference peak position range of. When the output unit may output the result of comparison with the reference peak of the range of the information or, the peak position of the analyzed ⁴⁰ K ⁴⁰ K for the detection of radioactive elements, the detection of radioactive elements is determined by the risk of radioactive material an alarm signal Can be printed.

As shown in FIG. 2, as shown in FIG. 2, the radiation detector 100 is installed so as to face the side and the upper surface of the vehicle on a path through which the vehicle can travel. Can be detected.

Meanwhile, FIG. 3 schematically shows a radiation detector according to another embodiment of the present invention.

The radiation detector 200 shown in FIG. 3 includes an input unit 210 that receives energy emitted from a radioactive element and converts it into an electric signal, a signal processing unit 220 that processes an electric signal received from the input unit 210, and a signal. It includes a control unit 130 that analyzes the signal received from the processing unit 220 to detect a nuclide of a radioactive element. The input unit 210 includes a scintillator 111 and a photomultiplier tube 112, and the arrangement of the scintillator 111 and the photomultiplier tube 112 or the number of photomultiplier tubes 112 are somewhat modified. . The signal processing unit 220 is a component that is slightly modified according to the structure of the input unit 210, but the function is the same as described above.

As shown in FIG. 4, the radiation detector 200 is installed so as to face both sides of the vehicle on a path through which the vehicle can travel, so as to detect nuclides of radioactive elements included in the cargo loaded on the driving vehicle. I can.

Conventional scintillation detectors have a tendency to decrease the accuracy of nuclide analysis due to the limitation of energy resolution, and tend to have a wide distribution of the Compton edge region in the energy spectrum, and thus nuclides with similar Compton edges (e.g., ⁶⁰ Co (theoretical Compton edge : 1.041 MeV) and ⁴⁰ K (theoretical Compton edge: 1.243 MeV)) have a very difficult problem to distinguish. In addition, there is a limit to improving the reliability of nuclide discrimination for a plurality of radiation sources at peak positions in the conventional energy weighted spectrum.

The radiation detectors 100 and 200 according to the present invention are capable of discriminating radionuclides even under conditions of low measurement efficiency by using a new radiation detection method using an additional algorithm that can further emphasize the peak value of the existing energy weighted spectrum. And, it is possible to increase the accuracy of radionuclide identification. In addition, the radiation detectors 100 and 200 according to the present invention ^{measure a peak value of 40} K included in the background radiation by applying a new analysis algorithm to more accurately detect a change in background radiation and automatically output the output accordingly. Can be corrected.

First, a method of detecting a change in background radiation and automatically correcting the output is as follows.

The correction of the output of the radiation detector according to the change in background radiation is performed when the radiation detector is in the standby mode, and a specific method thereof is as shown in FIG. 5. That is, the output correction method of the radiation detector includes determining whether the radiation detector is in an operation mode (S10), measuring the background radiation Rb (S20), and weighting the energy spectrum of the background radiation Rb. Generating a background radiation energy weighted spectrum (S30) ^{, calculating a 40} K peak position (Pb) from the background radiation energy weighted spectrum (S40), and setting the ⁴⁰ K peak position (Pb) to a preset reference peak the method comprising the step (S50) for comparing the location range, and the step (S60) to ⁴⁰ K of the peak position (Pb) is calculated for the absolute magnitude outside the predetermined reference peak position range, correcting the output of the radiation detector (S70) Includes.

First, it is determined whether the radiation detector is in an operation mode (S10), and when it is determined that the radiation detector is not in an operation mode but in a standby mode, the background radiation Rb is measured and output correction of the radiation detector according to the background radiation change is performed. On the other hand, when it is determined that the radiation detector is in the operation mode, the radiation detection step S80 is performed. The radiation detection step S80 is a step of detecting radiation by receiving energy emitted from a radioactive element and determining a nuclide of the radioactive element. A specific method of the radiation detection step S80 will be described later.

In the step of measuring the background radiation (S20), the background radiation Rb is measured, and spectral data for the background radiation Rb is collected. ^{Information of 40} K necessary for stabilization of the radiation detector can be extracted from the background radiation Rb.

Next, the step of generating a background radiation energy weighted spectrum by weighting the energy spectrum of the background radiation Rb (S30) is ^{a step of signal processing the collected background radiation spectrum so that the 40} K Compton edge is highlighted in a peak shape. to be. In this step, the energy weighting factor (Cw) is calculated by applying each energy as a weight for each channel to the energy spectrum of the measured background radiation (Rb), and the x-axis as the energy value and the y-axis as the energy weighting factor (Cw). Background radiation energy weighted spectrum.

Here, the energy weighting factor Cw can be calculated by the following equation.

Cw = (C x E) ⁿ x E ^m

Here, C is the photon count collected in each channel, E is the energy of each channel, and n and m are constants. The constant n is a natural number greater than or equal to 2, and the constant m is a natural number greater than or equal to 1. The energy weighting factor Cw is equally used in the process of generating an energy weighted spectrum in order to discriminate a nuclide of a radioactive element in the radiation detection step S80.

In the above formula for calculating the energy weighting factor (Cw), (C x E) ⁿ weighting is n squared at the start and end positions of the half width when there is a peak value close to the Gaussian distribution through the energy weighting method. It has the effect of bringing it closer to the center of the peak value after. That is, a new peak value obtained by multiplying an existing peak function by n has a width narrower than that of an existing peak value, thereby increasing the detection accuracy of the peak value.

And in the above equation, since E ^m is a coefficient in the form of a high-order function, there is an effect of maximizing the emphasis on the low count of the region as it goes to the high energy region.

In the above equation, the constants n and m can be selected according to the nuclide of interest. As the number increases, the peak value becomes clearer, but the probability of occurrence of errors in the peak position information due to statistical fluctuations increases, and computational processing Since it increases time, it is better to limit the range according to the type of specific nuclide of interest. The specific nuclear material required by the international standard can be detected within the energy range of 0 to 2.5 MeV. Therefore, in consideration of this point, it is preferable that both the constants n and m are 3 or less.

Next, to calculate the peak position (Pb) of ⁴⁰ K from the background radiation energy spectrum weighting (S40). ^{The peak position Pb of 40} K in the background radiation energy weighted spectrum can be calculated through various peak detection algorithms used in signal processing. Since the background radiation energy weighted spectrum best highlights the ⁴⁰ K Compton edge included in the background radiation in the form of a peak, it is possible to more accurately calculate the ^{40 K peak position (Pb).}

6 and 7, the energy weighting spectrum generated by applying the new energy weighting factor (Cw) proposed in the present invention has a peak indicating the Compton edge of the radioactive element compared to the energy weighting spectrum generated by the conventional method. You can see that it is more clearly revealed.

6 and 7 show energy weighted spectra of ⁴⁰ K analyzed using a conventional method and a control method of a radiation detector according to an exemplary embodiment of the present invention for an experimental example. In this experimental example, the spectrum was detected through repeated measurements four times while moving a radioactive element ^{of 40 K at 5 km/h, and a spectrum of 60} Co was also displayed on the graph for comparison of the peak positions.

6 is an energy weighted spectrum generated by a conventional method with an energy weighting factor (Cw) as CE. Referring to FIG. 6, ^{a spectrum generated from a moving 40} K is analyzed by a conventional method to determine the peak value position. It can be seen that it is not easy.

^{7 is an energy weighted spectrum generated by using an energy weighting factor (Cw) as C 3} E ⁶ (n is 3, m is 3) through a radionuclide detection method according to an embodiment of the present invention. It can be seen that it is easy to distinguish the energy range in which the peak value of ^{40 K appears.}

Next, ^{the step of comparing the 40} K peak position (Pb) with a preset reference peak position range (S50) is that the ⁴⁰ K peak position (Pb) calculated from the background radiation energy weighted spectrum is the reference peak position range of ^{40 K.} It is a step to check whether it is within or not. Here, the reference peak position a range of ⁴⁰ K may be stored to represent the Compton edge value of ⁴⁰ K when the optimum operation of the radiation detector, is previously set by experiments or analysis of the radiation detector. In this step, if the calculated ^{peak position (Pb) of 40} K is less than or equal to the minimum value (Pr1) of the preset reference peak position range, or more than the maximum value (Pr2) of the preset reference peak position range, the peak position of ^{40 K (} It may be determined that Pb) is out of a preset reference peak position range.

Next, ⁴⁰ K of the peak position (Pb) is pre-set based on the peak position range the out of the step (S60) for calculating the absolute size by the following formula of ⁴⁰ K of the peak position (Pb) is pre-set based on the peak position range Calculate the absolute size outside of.

|Pb-Pr|

In this equation, Pr denotes a preset reference peak position, and may be a minimum value Pr1 or a maximum value Pr2 of a preset reference peak position range.

Next, in the step of correcting the output of the radiation detector (S70), the output of the radiation detector is corrected according to the peak position Pb of ^{40 K.} In this step, the output of the radiation detector may be corrected by increasing or decreasing the output of the radiation detector in proportion to the absolute size of the ^{40 K peak position Pb out of the preset reference peak position range.}

In addition, the output correction of the radiation detector is a method of adjusting the variable resistance of the signal processing unit 120, a method of adjusting the voltage supplied to the photomultiplier tube 112 of the input unit 110, or a digitized spectrum using a software method. It can be performed in a variety of ways, such as a method of moving the peak in.

This correction of the output of the radiation detector can be repeated periodically when the radiation detector is in the standby mode.

In this way, by applying a weight to the background radiation spectrum to generate a background radiation energy weighted spectrum, the ⁴⁰ K Compton edge present in the background radiation is changed into a peak shape, and the output of the radiation detector is automatically corrected using this information. By automatically performing, it is possible to stabilize the output of the radiation detector regardless of changes in the external environment, and to improve the radiation detection accuracy of the radiation detector. ^{In particular, the present invention can change the 40} K Compton edge present in the background radiation into a more clear peak shape through an additional algorithm that further emphasizes the peak value of the existing energy weighted spectrum, and thus, the background radiation under the condition of low measurement efficiency. It is possible to more accurately check the change in and calibrate the output of the radiation detector accordingly.

Meanwhile, in the radiation detection step S80, the radiation detector may more accurately detect the radiation emitted from the radioactive element in a state corrected according to changes in the external environment as described above.

The radiation detection step (S80) includes receiving energy generated from a radioactive element, calculating an energy weighting factor (Cw) by applying each energy as a weight for each channel to the spectrum of the input energy, and applying the weighted energy. It may comprise the step of detecting the nuclide of the radioactive element based on the weighted spectrum.

Here, the energy weighting factor Cw may be calculated in the same manner as described above. After the energy weighting factor (Cw) is calculated, an energy weighted spectrum using the x-axis as the energy value and the y-axis as the energy weighting factor (Cw) is generated, and radionuclides of the radioactive element can be detected based on the generated energy weighting spectrum. . That is, it is possible to detect the nuclide of the radioactive element by comparing the energy value corresponding to the peak value of the energy weighting factor (Cw) of the radioactive element in the generated energy weighting spectrum with the energy values of the Compton's edge of the radioactive element.

Here, energy values of Compton's edges of specific radioactive elements according to the energy weighting factor Cw may be databased through pre-detection of each radioactive element.

6 to 15 show energy weighted spectra of some radioactive elements experimentally derived.

First, looking at one experimental example shown in FIGS. 6 and 7, as described above, the energy weighted spectrum generated by applying the new energy weighting factor (Cw) proposed in the present invention is compared to the energy weighted spectrum generated by the conventional method. In comparison, it can be seen that the peak indicating the Compton edge of the radioactive element is more clearly revealed.

Meanwhile, FIG. 8 shows ^{the energy spectrum of 60} Co and ⁴⁰ K according to another experimental example, and FIG. 9 shows the energy weighted spectrum of ⁶⁰ Co and ⁴⁰ K analyzed using a conventional method for the experimental example of FIG. 8. 10 and 11 show energy weighted spectra of ⁶⁰ Co and ⁴⁰ K, respectively, analyzed using the radionuclide detection method according to an embodiment of the present invention for the experimental example of FIG. 8.

This experimental example differs only in the detection date compared to the experimental example described above, and the other conditions are the same.

As shown in Fig. 8, it is not possible to confirm the position of the peak value ^{of 40} K in the spectrum to which the weight is not applied, and as shown in Fig. 9, the peak value by analyzing the spectrum generated from the ^{moving 40 K by a conventional method.} It can be seen that it is not easy to distinguish the range of energy that appears.

^{10 is an energy weighted spectrum generated by using an energy weighting factor (Cw) as C 2} E ³ (n is 2, m is 1) through a radionuclide detection method according to an embodiment of the present invention. It can be seen that it is easy to distinguish the energy range in which the peak value of ^{40 K appears.}

^{11 is an energy weighted spectrum generated by using an energy weighting factor (Cw) of C 3} E ⁶ (n is 3, m is 3) through a radionuclide detection method according to an embodiment of the present invention. It can be seen that it is easy to distinguish the energy range in which the peak value of ^{40 K appears.}

Meanwhile, FIG. 12 shows ^{the energy spectrum of 137} Cs and ⁶⁰ Co according to another experimental example, and FIG. 13 shows the energy weighted spectrum of ¹³⁷ Cs and ⁶⁰ Co analyzed using a conventional method for the experimental example of FIG. 12. 14 and 15 show energy weighted spectra of ¹³⁷ Cs and ⁶⁰ Co, respectively, analyzed using the radionuclide detection method according to an embodiment of the present invention for the experimental example of FIG. 12.

In this experimental example, the spectrum was detected through 10 repeated measurements while moving two kinds of radioactive elements ^{of 137} Cs and ^{60 Co at 5 km/h.}

As shown in FIG. 12, the positions of the peak values of ¹³⁷ Cs and ⁶⁰ Co in the spectrum to which the weight is not applied cannot be confirmed.

As shown in FIG. 13, as ^{a result of analyzing the spectrum generated from moving 137} Cs and ⁶⁰ Co by a conventional method, it can be seen that the energy range in which the peak value appears is relatively wide.

^{14 is an energy weighted spectrum generated by using an energy weighting factor (Cw) as C 2} E ³ (n is 2, m is 1) through a radionuclide detection method according to an embodiment of the present invention. It can be seen that the energy range in which the peak values of ¹³⁷ Cs and ^{60 Co appear relatively narrow.}

^{15 is an energy weighted spectrum generated by using an energy weighting factor (Cw) as C 3} E ⁶ (n is 3, m is 3) through a radionuclide detection method according to an embodiment of the present invention. It can be seen that the energy range in which the peak values of ¹³⁷ Cs and ^{60 Co appear relatively narrow.}

As can be seen from these experimental examples, the present invention uses an additional algorithm that further emphasizes the peak value of the existing energy weighted spectrum, so that radionuclides can be discriminated under conditions of low measurement efficiency in which radioactive elements move, and The accuracy of the discrimination can be improved.

The energy range in which the peak value appears in the energy weighting spectrum generated by the energy weighting factor (Cw) calculation formula according to the present invention varies depending on the nuclide, and the radioactivity to be detected depends on the constants n and m of the energy weighting factor (Cw) calculation The energy range in which the element's peak value appears varies.

Therefore, in order to further increase the detection accuracy, two or more energy weighting factors (Cw) are calculated by differently from the constant n and m, and two or more energy weighting spectra are generated for the two or more energy weighting factors (Cw). It is possible to use a method to detect the nuclide of.

That is, the energy values corresponding to the peak values of the two or more energy weighting coefficients (Cw) for the radioactive element in each of the two or more energy weighting spectra are calculated as the Compton of the radioactive elements preset for the two or more energy weighting coefficients (Cw). By comparing each of the energy values of the edge to detect the nuclide of the radioactive element, it is possible to increase the detection accuracy of the nuclide.

Here, energy values of Compton's edges of specific radioactive elements according to two or more energy weighting factors (Cw) may be databased through pre-detection of each radioactive element.

For example, as shown in Figs. 14 and 15, ^{two energy weighting spectra are generated by setting the energy weighting factor (Cw) to C 2} E ³ and C ³ E ^6, and the radioactive element in each of the two energy weighting spectra is The peak value may be compared with the energy values of the Compton's edge of the radioactive elements preset for the two energy weighting factors Cw to detect the nuclide of the radioactive element.

As shown in Fig. 14, the energy range at which the peak value ^{of 137} Cs appears in the energy weighting spectrum generated by setting the energy weighting factor (Cw) as C ² E ^{3 (n is 2, m is 1) corresponds to C,} As shown in Fig. 15, the energy range at which the peak value ^{of 137} Cs appears in the energy weighting spectrum generated by setting the energy weighting factor (Cw) to C ³ E ^{6 (n is 3, m is 3) corresponds to E.} Therefore, in the energy weighting spectrum generated by setting the energy weighting factor (Cw) as C ² E ³ (n is 2, m is 1), the energy range in which the peak value of the radioactive element to be detected appears is in the region C, and the energy When the energy range in which the peak value of the radioactive element to be detected appears in the energy weighting spectrum generated by setting the weighting factor (Cw) as C ³ E ^{6 (n is 3, m is 3) satisfies all the conditions in the E region.} , The radioactive element can be identified ^{as 137 Cs.}

As another example, as shown in FIG. 14, the energy range at which the peak value ^{of 60} Co appears in the energy weighting spectrum generated by setting the energy weighting ^{factor (Cw) to C 2} E ^{3 (n is 2, m is 1) is in D.} As shown in Fig. 15, the energy range at which the peak value ^{of 60} Co appears in the energy weighting spectrum generated by setting the energy weighting ^{factor (Cw) to C 3} E ^{6 (n is 3, m is 3) is F} Corresponds. Therefore, in the energy weighting spectrum generated by setting the energy weighting factor (Cw) as C ² E ³ (n is 2, m is 1), the energy range in which the peak value of the radioactive element to be detected appears is in the region D, and the energy When the energy range in which the peak value of the radioactive element to be detected appears in the energy weighted spectrum generated by setting the weighting factor (Cw) to C ³ E ^{6 (n is 3, m is 3) satisfies all the conditions in the F region.} , The radioactive element can be identified ^{as 60 Co.}

Alternatively, the three types of energy-weighted spectra can be comprehensively analyzed to detect radioactive element nuclides.

^{For example, as shown in FIG. 13, since the energy range in which the peak value of 137} Cs appears in the energy weighting spectrum generated by using the energy weighting factor (Cw) as CE corresponds to A, the peak value of a specific radioactive element appears. The energy range is located in the area A in the energy weighting factor (Cw) CE, and in the energy weighting factor (Cw) C ² E ³ in the C area, and in the energy weighting factor (Cw) C ³ E ⁶ When all the conditions located in the E region are satisfied, the radioactive element can be determined ^{as 137 Cs.}

^In the case of 60 Co, as shown in Fig. 13, since the energy range at which the peak value appears in the energy weighting spectrum generated by using the energy weighting factor (Cw) as CE corresponds to B, the energy at which the peak value of a specific radioactive element appears. The range is, the energy weighting factor (Cw) is located in the region B in CE, the energy weighting factor (Cw) ^{is located in the region D from C 2} E ³ and the energy weighting factor (Cw) C ³ E ⁶ to F When all the conditions located in the region are satisfied, the radioactive element can be determined ^{as 60 Co.}

In this way, a plurality of energy weighted spectra are generated by making the energy weighting coefficient Cw different from the constant n and m, and the plurality of energy weighted spectra are analyzed to increase the accuracy of nuclide detection.

Although a preferred example has been described for the present invention, the scope of the present invention is not limited to the form described and illustrated above.

For example, in the calculation formula Cw = (C x E) ⁿ x E ^m of the energy weighting factor (Cw), the constant n is not limited to 2 or 3 described above, but can be various natural numbers of 2 or more, and the constant m It is not limited to 1 or 3 described above, but may be a variety of natural numbers of 1 or more.

In addition, the radiation detector according to the present invention does not discriminate even the nuclides of the radioactive element as described above in the radiation detection step, and corrects the output according to the change in background radiation and can measure the radiation dose of the specific radioactive element.

In addition, it was previously described that the output of the radiation detector is corrected by increasing or decreasing the output of the radiation detector in proportion to the absolute size of the ^{40 K peak position (Pb) out of the preset reference peak position range.} The output correction of the detector can be performed in a variety of other ways other than this one.

As described above, the present invention has been illustrated and described in connection with a preferred embodiment for illustrating the principle of the present invention, but the present invention is not limited to the configuration and operation as shown and described as such. Rather, it will be well understood by those skilled in the art that many changes and modifications can be made to the present invention without departing from the spirit and scope of the appended claims.

100, 200: radionuclide detection device 110, 210: input unit
111: scintillator 112: photomultiplier tube
120, 220: signal processing unit 130: energy analysis unit

Claims (10)

In the control method of a radiation detector for detecting radiation generated from a radioactive element,
(a) determining whether the radiation detector is in an operation mode;
(b) measuring background radiation when the radiation detector is not in an operation mode;
(c) Background radiation energy with an energy weighting factor (Cw) being calculated by applying each energy as a weight for each channel to the energy spectrum of the measured background radiation, and the x-axis as the energy value and the y-axis as the energy weighting factor (Cw). Generating a weighted spectrum;
(d) calculating a peak position (Pb) ^{of 40} K from the background radiation energy weighted spectrum;
(e) comparing the reference peak position range of the peak position (Pb) of the predetermined ⁴⁰ K; And
(f) If the ⁴⁰ K of the peak position (Pb) is out of the predetermined range based on the peak position, correcting the output of the radiation detector; includes,
The energy weighting factor Cw satisfies the following equation.
Cw = (C x E) ⁿ x E ^m
(C: photon count collected in each channel, E: energy of each channel, n: natural number greater than or equal to 2, m: natural number greater than or equal to 1)
The method of claim 1,
In the above formula, both the constants n and m are 3 or less control method of the radiation detector.
The method of claim 1,
After step (a),
(g) receiving energy generated from a radioactive element when the radiation detector is in an operation mode;
(h) applying the energy weighting factor (Cw) to the spectrum of the input energy to generate an energy weighted spectrum using an x-axis as an energy value and a y-axis as the energy weighting factor (Cw); And
(i) Detecting the nuclide of the radioactive element based on the energy weighted spectrum, and an energy value corresponding to the peak value of the energy weighting factor (Cw) for the radioactive element is the energy of the Compton edge of the radioactive elements preset And detecting a nuclide of the radioactive element by comparing the values with the values.
The method of claim 3,
Two or more of the energy weighting coefficients (Cw) are calculated by differently from the constant n and m, and two or more of the energy weighted spectra are generated for the two or more energy weighting coefficients (Cw),
In the step (i), an energy value corresponding to a peak value of the two or more energy weighting coefficients (Cw) for the radioactive element in each of the two or more energy weighting spectra is the two or more energy weighting coefficients (Cw) And detecting a nuclide of the radioactive element by comparing each of the energy values of the radioactive elements preset with respect to Compton's edge.
The method of claim 1,
In step (f),
The control method of a radiation detector, characterized in that the output of the radiation detector is increased or decreased in proportion to an absolute magnitude in which ^{the 40 K peak position (Pb) is out of a preset reference peak position range.}
In a radiation detector for detecting radiation emitted from a radioactive element,
An input unit that receives background radiation and radiation emitted from the radioactive element and converts it into an electrical signal;
A signal processing unit processing an electric signal received from the input unit;
An energy spectrum for background radiation and an energy spectrum for radiation of the radioactive element are respectively generated from the signal received from the signal processing unit, and each energy is applied as a weight for each channel to the generated energy spectrum, and an energy weighting factor (Cw ) Is calculated, and an energy weighted spectrum is generated with the x-axis as the energy value and the y-axis as the energy weighting factor (Cw) for the background radiation, and the background radiation energy weighted spectrum is generated, and the x-axis for the radiation of the radioactive element An energy weighted spectrum with the y-axis as the energy weighting factor (Cw) is generated as an energy value, and the energy value corresponding to the peak value of the energy weighting factor (Cw) for the radioactive element is determined by the Compton edge of the radioactive elements. Including; a control unit for detecting the nuclide of the radioactive element by comparing with energy values,
The control unit,
^{The 40} K peak position (Pb) is calculated from the background radiation energy weighted spectrum ^{, and the 40} K peak position (Pb) is compared with a preset reference peak position range, and the ⁴⁰ K peak position (Pb) is preset. If it is out of the set reference peak position range, the output of the radiation detector is corrected,
The energy weighting factor (Cw) is a radiation detector, characterized in that satisfies the following equation.
Cw = (C x E) ⁿ x E ^m
(C: photon count collected in each channel, E: energy of each channel, n: natural number greater than or equal to 2, m: natural number greater than or equal to 1)
The method of claim 6,
The input unit,
A scintillator that converts incident radiation into visible light,
And a photomultiplier tube connected to the scintillator to focus visible light generated from the scintillator and convert it into an electrical signal.
The method of claim 6,
In the above formula, both of the constants n and m radiation detector, characterized in that 3 or less.
The method of claim 6,
The control unit,
Two or more of the energy weighting coefficients (Cw) are calculated by differently from the constant n and m, and two or more of the energy weighting spectra are generated for the two or more energy weighting coefficients (Cw), and the two or more energy weighting factors Energy values corresponding to the peak values of the two or more energy weighting coefficients (Cw) for the radioactive elements in each spectrum, and the energy values of the Compton edge of the radioactive elements preset for the two or more energy weighting coefficients (Cw). A radiation detector, characterized in that for detecting a nuclide of the radioactive element by comparing with each.
The method of claim 6,
The control unit,
A radiation detector, characterized in that the ⁴⁰ K to the peak position (Pb) is proportional to the absolute magnitude outside the predetermined range based on the peak position to increase or decrease the output of the radiation detector.

Images