Spectrum stabilization method for radionuclide analysis and system therefor

Abstract

The spectrum stabilization method for radionuclide analysis according to the present invention comprises a scintillation generation step, an electrical signal generation step, an original spectrum generation step, a corrected spectrum generation step, and a spectroscopic analysis performance step. In the scintillation generation step, a plurality of scintillators absorb radiation in the form of electromagnetic waves to generate scintillations. In the electrical signal generation step, a plurality of photosensors corresponding one-to-one with the plurality of scintillators convert the scintillations into electrical signals. In the original spectrum generation step, a first computational unit generates a plurality of original spectra based on the electrical signals. In the corrected spectrum generation step, a second computational unit divides each of the plurality of original spectra into a plurality of energy intervals and linearly corrects each of the plurality of energy intervals. Additionally, the second computational unit corrects the plurality of original spectra by applying a weight different from that applied to the remaining areas to the peak areas of each of the plurality of original spectra. Additionally, the second computational unit generates corrected spectra through the process described above.

Description

Technology Field

[0001] The present invention relates to a spectrum stabilization method and system for radionuclide analysis. Specifically, the invention relates to a spectrum stabilization method and system that applies different weights to peak regions, divides the spectrum into multiple sections, and linearly corrects each of the sections. Background Technology

[0002] PET (Positron Emission Tomography) refers to a method of diagnosing diseases within the body using radiation emitted from radionuclides. A PET diagnostic device includes a detector for detecting radiation. Generally, silicon photomultiplier tubes are used as detectors.

[0003] However, detectors using silicon photomultiplier tubes exhibit non-linear response characteristics due to factors such as operating voltage saturation and temperature dependence. In particular, in the case of arrayed silicon photomultiplier tubes, each scintillator-photosensor assembly has a different gain due to various factors (measurement environment, structural differences between scintillator-photosensor assemblies, etc.). Consequently, each scintillator-photosensor assembly can generate a different spectrum for radiation of the same energy. Generally, this phenomenon is described as "spectrum drifting according to the gain of the scintillator-photosensor assembly" or "spectral drift occurring."

[0004] Spectrum drift reduces the accuracy of radionuclide analysis. To prevent this problem, the gain is corrected for each scintillator-photosensor assembly; this process is called spectrum stabilization.

[0005] However, when using conventional spectrum stabilization methods, only linear correction across the entire spectrum is possible. Therefore, there was a limitation in that conventional spectrum stabilization methods could not be applied to arrayed silicon photomultiplier tubes with non-linearity response characteristics. The problem to be solved

[0006] The present invention aims to solve the aforementioned limitations by providing a spectrum stabilization method and a system for the same that can be applied to silicon photomultiplier tubes having non-linear response characteristics, by applying different weights to peak regions and dividing the spectrum into multiple sections to linearly correct each of the sections. means of solving the problem

[0007] A spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention may include a scintillation generation step, an electrical signal generation step, an original spectrum generation step, a corrected spectrum generation step, and a spectroscopic analysis performance step.

[0008] In the scintillation generation stage, multiple scintillators can absorb radiation in the form of electromagnetic waves to generate scintillations.

[0009] In the electrical signal generation step, a plurality of light sensors corresponding one-to-one to the plurality of scintillators can convert the scintillations into electrical signals.

[0010] In the original spectrum generation step, the first operation unit can generate a plurality of original spectra based on the electrical signal.

[0011] In the correction spectrum generation step, the second operation unit can divide each of the plurality of original spectra into a plurality of energy intervals and linearly correct each of the plurality of energy intervals. Additionally, the second operation unit can correct the plurality of original spectra by applying a weight different from the weight applied to the remaining area to the peak area of ​​each of the plurality of original spectra. Furthermore, the second operation unit can generate a plurality of corrected spectra through the correction.

[0012] In the spectral analysis execution step, the third computational unit can perform spectral analysis based on the plurality of correction spectra.

[0013] A spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention. The correction spectrum generation step may include a reference spectrum selection step, an energy interval division step, a correction value determination step, and a spectrum correction step.

[0014] In the reference spectrum selection step, the second operation unit can select any one of the plurality of original spectra as the reference spectrum.

[0015] In the energy interval division unit, the second operation unit can divide each of the plurality of original spectra into a plurality of energy intervals.

[0016] In the correction value determination step, the second operation unit can calculate a final-correction value that minimizes the value of the objective function for each of the plurality of energy intervals of each of the plurality of original spectra.

[0017] In the spectrum correction step, the second operation unit can correct the plurality of original spectra based on the plurality of final-correction values ​​to generate the plurality of corrected spectra.

[0018] In the correction value determination step of the spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention, the first spectrum may be any one of the plurality of original spectra. The first energy range may be any one of the plurality of energy ranges of the first spectrum. The correction value determination step may include a step of calculating an objective function value for each correction value, a step of calculating a final-corrected value for a target range, and a step of iterative calculation for each energy range.

[0019] In the step of calculating objective function values ​​for each correction value, the second operation unit can calculate multiple objective function values ​​corresponding to multiple correction values ​​for the first energy interval.

[0020] In the step of calculating the final correction value of the target section, the second operation unit can calculate a final correction value that is a correction value corresponding to the smallest objective function value among the plurality of objective function values.

[0021] In the iterative calculation step for each energy interval, the second operation unit may repeatedly perform the objective function value calculation step and the correction value calculation step for each of the plurality of energy intervals of each of the plurality of original spectra.

[0022] In the step of calculating objective function values ​​for each correction value of the spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention, the second operation unit may calculate the plurality of objective function values ​​using the following mathematical formulas 1 to 5. In addition, in the spectrum correction step, the second operation unit may generate the plurality of corrected spectra by correcting the plurality of original spectra based on the plurality of final correction values ​​and the following mathematical formulas 1 to 3.

[0023] [Mathematical Formula 1]

[0024]

[0025] (Here, k is the correction value, and n represents the energy level)

[0026] [Mathematical Formula 2]

[0027]

[0028] [Mathematical Formula 3]

[0029]

[0030] (Here, is the coefficient value of the corrected original spectrum corresponding to energy level n and correction value k, represents the coefficient value of the original spectrum corresponding to energy level n)

[0031] [Mathematical Formula 4]

[0032]

[0033] (Here, represents the weight corresponding to energy level n, t<1)

[0034] [Mathematical Formula 5]

[0035]

[0036] (Here, is the objective function, N is the maximum energy level within the above energy interval, is the coefficient value of the reference spectrum corresponding to energy level n, represents the coefficient value of the corrected spectrum corresponding to the energy level n)

[0037] In the step of calculating the objective function value for each correction value of the spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention, each of the plurality of correction values ​​may be 0.5 or more and 2.0 or less.

[0038] In the step of calculating the final correction value for each section of the spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention, the second operation unit can calculate the final correction value using at least one of a grid search method and an optimization algorithm.

[0039] In the reference spectrum selection step of the spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention, the second computational unit may select the reference spectrum based on the sum of the count values ​​for each energy level, the count values ​​in the peak region, and the resolution of the detector.

[0040] In the energy interval division step of the spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention, the second computational unit may divide each of the plurality of original spectra into a first energy interval, a second energy interval, and a third energy interval. The maximum energy level of the first energy interval may be smaller than the minimum energy level of the second energy interval. The maximum energy level of the second energy interval may be smaller than the minimum energy level of the third energy interval.

[0041] A spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention may further include a step of displaying analysis results. In the step of displaying analysis results, the display unit may provide an image corresponding to at least one of the result of the spectroscopic analysis, the plurality of original spectra, and the plurality of corrected spectra.

[0042] Each of the plurality of optical sensors in the spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention is a silicon photomultiplier and may include a Geiger-Mode Avalanche Photodiode (GAPD).

[0043] A radiation detection system to which a spectrum stabilization method according to one embodiment of the present invention is applied may include a detection unit, a first operation unit, a second operation unit, a third operation unit, a display unit, and a power supply unit.

[0044] The detection unit may include a plurality of scintillators and a plurality of optical sensors. The plurality of scintillators may absorb radiation in the form of electromagnetic waves to generate scintillations. The plurality of optical sensors may convert the scintillations into electrical signals.

[0045] The first operation unit can generate a plurality of original spectra based on the electrical signal.

[0046] The second operation unit can divide each of the plurality of original spectra into a plurality of energy intervals and linearly correct each of the plurality of energy intervals. Additionally, the second operation unit can correct the plurality of original spectra by applying a weight different from the weight applied to the remaining area to the peak area of ​​each of the plurality of original spectra. Furthermore, the second operation unit can generate a plurality of corrected spectra through the correction.

[0047] The third operation unit can perform spectroscopic analysis based on the plurality of correction spectra.

[0048] The display unit can provide an image corresponding to at least one of the result of the spectroscopic analysis, the plurality of original spectra, and the plurality of corrected spectra.

[0049] The power supply unit can supply power to each component.

[0050] The plurality of optical sensors can be coupled to the lower portions of the plurality of scintillators. The plurality of optical sensors can correspond one-to-one with the plurality of scintillators.

[0051] The second operation unit of a radiation detection system to which a spectrum stabilization method according to an embodiment of the present invention is applied may select any one of the plurality of original spectra as a reference spectrum. Additionally, the second operation unit may divide each of the plurality of original spectra into a plurality of energy intervals. Furthermore, the second operation unit may calculate a final-correction value that minimizes the value of an objective function for each of the plurality of energy intervals. Additionally, the second operation unit may generate a plurality of corrected spectra by correcting the plurality of original spectra based on the plurality of final-correction values.

[0052] The second operation unit of a radiation detection system to which a spectrum stabilization method according to one embodiment of the present invention is applied can calculate a plurality of objective function values ​​corresponding to a plurality of correction values ​​for each of the plurality of energy intervals. In addition, the second operation unit can calculate the final-correction value, which is a correction value corresponding to the smallest objective function value among the plurality of objective function values.

[0053] The second operation unit of a radiation detection system to which a spectrum stabilization method according to one embodiment of the present invention is applied can calculate the plurality of objective function values ​​using the following mathematical formulas 1 to 5. In addition, the second operation unit can generate the plurality of corrected spectra by correcting the plurality of original spectra based on the plurality of final correction values ​​and the following mathematical formulas 1 to 3.

[0054] [Mathematical Formula 1]

[0055]

[0056] (Here, k is the correction value, and n represents the energy level)

[0057] [Mathematical Formula 2]

[0058]

[0059] [Mathematical Formula 3]

[0060]

[0061] (Here, is the coefficient value of the corrected original spectrum corresponding to energy level n and correction value k, represents the coefficient value of the original spectrum corresponding to energy level n)

[0062] [Mathematical Formula 4]

[0063]

[0064] (Here, represents the weight corresponding to energy level n, t<1)

[0065] [Mathematical Formula 5]

[0066]

[0067] (Here, is the objective function, N is the maximum energy level within the above energy interval, is the coefficient value of the reference spectrum corresponding to energy level n, represents the coefficient value of the corrected spectrum corresponding to the energy level n)

[0068] Each of the plurality of correction values ​​of a radiation detection system to which a spectrum stabilization method according to one embodiment of the present invention is applied may be 0.5 or more and 2.0 or less.

[0069] The second operation unit of the radiation detection system to which the spectrum stabilization method according to one embodiment of the present invention is applied can calculate the final-corrected value using at least one of a grid search method and an optimization algorithm.

[0070] The second operation unit of the radiation detection system to which the spectrum stabilization method according to one embodiment of the present invention is applied can select the reference spectrum based on the total sum of count values ​​by energy level, the count value in the peak region, and the resolution of the detector.

[0071] The second operation unit of a radiation detection system to which a spectrum stabilization method according to an embodiment of the present invention is applied may divide each of the plurality of original spectra into a first energy range, a second energy range, and a third energy range. The maximum energy level of the first energy range may be smaller than the minimum energy level of the second energy range. The maximum energy level of the second energy range may be smaller than the minimum energy level of the third energy range.

[0072] Each of the plurality of optical sensors of a radiation detection system to which a spectrum stabilization method according to one embodiment of the present invention is applied may be a silicon photomultiplier (SiPM).

[0073] Each of the plurality of optical sensors of a radiation detection system to which a spectrum stabilization method according to one embodiment of the present invention is applied may include a GAPD (Geiger-Mode Avalanche Photodiode). Effects of the invention

[0074] The present invention can provide a spectrum stabilization method and a system for the same that can be applied to silicon photomultiplier tubes having non-linear response characteristics by applying different weights to peak regions and dividing the spectrum into multiple sections and linearly correcting each of the sections. Brief explanation of the drawing

[0075] FIGS. 1 and 2 illustrate one of two types of arrayed silicon photomultiplier tubes to aid in understanding the present invention. Figures 3a and 3b are illustrated to explain the characteristics of spectra generated in a vacuum photomultiplier tube. Figures 4a and 4b are illustrated to explain the characteristics of spectra generated in a silicon photomultiplier tube. FIG. 5 is a block diagram of a radiation detection system (SRD) to which a spectrum stabilization method according to one embodiment of the present invention is applied. Figure 6 illustrates the peak region and multiple energy intervals on the spectrum as an example. FIG. 7 illustrates a flowchart of a spectrum stabilization method for radionuclide analysis according to one embodiment of the present invention. Figure 8 illustrates a detailed flowchart of the correction value determination step. FIGS. 9 and FIGS. 10 illustrate exemplary results of correcting the original spectrum using the present invention. Figure 11 shows a graph of the relative error between the correction spectrum and the reference spectrum calculated for each of the multiple scintillator-photosensor assemblies through repeated experiments. Specific details for implementing the invention

[0076] Preferred embodiments of the present invention will be described in more detail below with reference to the attached drawings. In the drawings, the proportions and dimensions of the components may be exaggerated for the effective explanation of the technical content.

[0077] Terms such as "include" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0078] In addition, when a component is described as "up," it refers to the area above or below the component, and does not necessarily mean that it is located on the upper side relative to the direction of gravity.

[0079] In addition, where it is stated that a component is "connected" or "combined" to another component, this may include not only cases where the component is directly connected or combined to the other component, but also cases where the component is indirectly connected or combined through another component.

[0080] In addition, terms such as "first," "second," etc., may be used to describe a component; however, these terms are intended merely to distinguish the component from other components and are not intended to limit the essence, order, or sequence of the component.

[0081] The following describes background technology to aid in understanding the present invention. Positron Emission Tomography (PET) is a method for diagnosing diseases within the body using radiation emitted from radionuclides. Specifically, PET involves the process of injecting a radiopharmaceutical containing radionuclides into a patient's vein and then imaging the radiation emitted from the radionuclides. A PET diagnostic device includes a gamma ray detector. The gamma ray detector includes a collimator, a scintillator, and a photo sensor.

[0082] The collimator acts as the lens of a standard camera.

[0083] A scintillator absorbs radiation to generate a scintillation in the UV (Ultraviolet Ray) or visible light spectrum. Scintillation refers to luminescence caused by radiation, and luminescence signifies a luminescence phenomenon that is not accompanied by heat.

[0084] A photo sensor absorbs scintillation to generate an electrical signal. A photomultiplier can be used as a photo sensor in a gamma-ray detector. Photomultipliers are broadly classified into vacuum tube photomultiplier tubes and silicon photomultipliers (SiPMs).

[0085] A photomultiplier is a photoelectric tube having one or more dynodes between a photocathode and an anode. A photoelectric tube refers to a device that generates a current corresponding to the intensity of light using the photoelectric effect.

[0086] Vacuum tube photomultiplier tubes have been used in PET diagnostic devices due to their advantages of high signal amplification rate, safety, and low noise ratio. However, their application in PET diagnostic devices has been limited due to the disadvantage of high magnetic field sensitivity.

[0087] In contrast, silicon photomultipliers (SiPMs) possess advantages such as low magnetic field sensitivity, high amplification rates, low operating voltage, small size, and low manufacturing costs. Consequently, silicon photomultipliers (SiPMs) are attracting attention as an alternative to vacuum tube photomultipliers.

[0088] A silicon photomultiplier (SiPM) consists of multiple Geiger-mode Avalanche Photodiodes (GAPDs). Additionally, hundreds or thousands of microcells are arranged in a two-dimensional array within each GAPD. Each microcell acts as an ON / OFF switch for incident radiation. Therefore, spectroscopic analysis of a specific radiation can be performed by counting the number of microcells that turn on when a specific radiation is incident.

[0089] For example, the higher the energy of the incident radiation, the larger the amplitude of the electrical signal generated through the photomultiplier. By classifying the generated electrical signals according to their amplitude, a spectrum of the radiation can be obtained. Based on the aforementioned spectrum, radionuclides can be analyzed, and this process is called spectroscopy.

[0090] Meanwhile, a single silicon photomultiplier tube has the disadvantage of having a low Photon Detection Efficiency (PDE) and a narrow measurable radiation energy range due to the finite number of microcells. To solve this problem, multiple silicon photomultipliers arranged in a matrix form (hereinafter referred to as arrayed silicon photomultipliers) are used. Arrayed silicon photomultipliers are classified into light-sharing arrayed silicon photomultipliers (hereinafter referred to as light-sharing type, LSP) and one-to-one coupling arrayed silicon photomultipliers (hereinafter referred to as one-to-one coupling type, OSP), depending on the method in which multiple scintillators and multiple photosensors are combined.

[0091] The present invention may be applied to the aforementioned arrayed silicon photomultiplier tube. Furthermore, the present invention relates to a spectrum stabilization method in an arrayed silicon photomultiplier tube (OSP) of a one-to-one coupling type. Hereinafter, to aid in understanding the present invention, the invention will be described with reference to FIGS. 1, 2, 3a, 3a, 4a, and 4b.

[0092] FIGS. 1 and 2 illustrate either of two types of arrayed silicon photomultiplier tubes (LSP, OSP) to aid in understanding the present invention. FIG. 1 illustrates an exemplary arrayed silicon photomultiplier tube (LSP) of the light-sharing type. FIG. 2 illustrates an exemplary arrayed silicon photomultiplier tube (OSP) of the one-to-one coupling type.

[0093] In the Light Sharing (LSP) method, a light guide is utilized. Specifically, scintillations generated from multiple scintillators (SCN) are distributed and transmitted to multiple photosensors (PTS) through a single light guide (LGD). Consequently, a single spectrum is generated through the multiple photosensors (PTS). While the Light Sharing (LSP) method provides high-resolution information, it has the disadvantage that light and energy information is lost during the light distribution process. Therefore, the accuracy of radionuclide analysis is relatively lower compared to cases using a one-to-one coupling method.

[0094] On the other hand, in the one-to-one coupling method (OSP), multiple scintillators (SCN) and multiple photosensors (PTS) are connected one-to-one (hereinafter, multiple scintillator-photosensor assemblies, STR). Accordingly, a spectrum is generated from each of the multiple scintillator-photosensor assemblies (STR). That is, since the light distribution process is not included, the loss of light and energy information can be minimized. Therefore, when using the one-to-one coupling method (OSP), radionuclides can be analyzed more accurately than when using the light sharing method (LSP).

[0095] FIGS. 3a and 3b are illustrated to explain the characteristics of spectra generated in a vacuum tube photomultiplier. FIG. 3a illustrates a vacuum tube photomultiplier and a plurality of spectra generated in the vacuum tube photomultiplier. FIG. 3b illustrates some of the spectra generated in the vacuum tube photomultiplier as an example.

[0096] Referring to Fig. 3a, when a spectrum is generated through a vacuum tube photomultiplier, spectrum drift may occur depending on the surrounding environment (especially temperature, T1 to Tn). This is because the gain of the vacuum tube photomultiplier may vary depending on the surrounding environment.

[0097] Referring to FIG. 3b, the spectra generated through the vacuum photomultiplier tube have the following characteristics: (1) Spectrum drift is linear, and (2) the statistical distribution between the spectra is identical. In the present invention, the statistical distribution refers to the distribution of count values ​​for each energy level on the spectrum.

[0098] FIGS. 4a and 4b are illustrated to explain the characteristics of spectra generated in a silicon photomultiplier tube. FIG. 4a illustrates a silicon photomultiplier tube and a plurality of spectra generated in the silicon photomultiplier tube. FIG. 4b illustrates some of the spectra generated in the silicon photomultiplier tube as an example.

[0099] Referring to FIG. 4a, when a spectrum is generated through a silicon photomultiplier tube, spectrum drift may occur due to the characteristics of the silicon photomultiplier tube and the gain difference between multiple scintillator-photosensor assemblies (STR). Specifically, the silicon photomultiplier tube has nonlinear response characteristics due to factors such as operating voltage saturation and temperature dependence. In particular, in the case of an array-type silicon photomultiplier tube, each scintillator-photosensor assembly may have a different gain due to structural differences between multiple scintillator-photosensor assemblies (STR).

[0100] Referring to Fig. 4b, the (3) spectrum drift of the spectra generated through the silicon photomultiplier tube is nonlinear, and (4) the statistical distribution between the spectra is not the same. That is, the spectra generated through the silicon photomultiplier tube have different characteristics ((3), (4)) from the spectra generated through the vacuum tube photomultiplier tube.

[0101] In summary, conventional spectrum stabilization methods have been studied based on the aforementioned characteristics ((1), (2)). That is, conventional spectrum stabilization methods have the limitation that they can only be applied to systems composed of a single detector with linear response characteristics. Furthermore, conventional spectrum stabilization methods have the problem of limited correction performance because they are limited to a method of correcting the entire energy range without dividing the spectrum into energy ranges.

[0102] Therefore, conventional spectrum stabilization methods cannot be applied to radiation detection systems based on silicon photomultiplier tubes, and there is a need to introduce a new spectrum stabilization method and a system that considers the characteristics of silicon photomultiplier tubes. The present invention aims to solve the problems of the aforementioned conventional spectrum stabilization methods. The invention proposed in this application will be described below.

[0103] FIG. 5 is a block diagram of a radiation detection system (SRD) to which a spectrum stabilization method according to one embodiment of the present invention is applied. FIG. 6 is an exemplary illustration of a peak region (PK) and a plurality of energy intervals (SC1, SC2, SC3) on the spectrum.

[0104] Referring to FIG. 5, a radiation detection system (SRD) with a spectrum stabilization method applied may include a detection unit (DTT), a computation unit (PRC), a display unit (DSP), and a power supply unit (BTT).

[0105] The detector (DTT) can absorb radiation (RDT) and generate an electrical signal (SGN). The detector (DTT) may include a plurality of scintillators (SCN) and a plurality of optical sensors (PTS).

[0106] Multiple scintillators (SCNs) can absorb radiation (RDT) in the form of electromagnetic waves to generate scintillations. Scintillation refers to luminescence caused by radiation (RDT), and luminescence refers to a luminescence phenomenon that is not accompanied by heat.

[0107] Multiple optical sensors (PTS) can convert the scintillations generated from multiple scintillators (SCN) into electrical signals (SGN). Multiple optical sensors (PTS) can be coupled to the lower portions of multiple scintillators (SCN). Multiple optical sensors (PTS) can correspond one-to-one with multiple scintillators (SCN).

[0108] In one embodiment of the present invention, each of the plurality of optical sensors (PTS) may be a silicon photomultiplier (SiPM). That is, the detector (DTT) of the present invention may be an array of silicon photomultipliers with a one-to-one coupling method as described above.

[0109] In one embodiment of the present invention, each of the plurality of optical sensors (PTS) may include a GAPD (Geiger-Mode Avalanche Photodiode).

[0110] The computation unit (PRC) can generate and correct a spectrum based on the electrical signal generated by the detection unit (DTT) and perform spectroscopic analysis. The computation unit (PRC) may include a first computation unit (PRC1), a second computation unit (PRC2), and a third computation unit (PRC3). For example, the first computation unit (PRC1), the second computation unit (PRC2), and the third computation unit (PRC3) may be devices such as a microprocessor, a central processing unit, a microcomputer, a controller, etc. However, the first computation unit (PRC1), the second computation unit (PRC2), and the third computation unit (PRC3) of the present invention are not limited thereto.

[0111] The first operation unit (PRC1) can generate a plurality of original spectra (SPT1) based on electrical signals (SGN) generated from a plurality of optical sensors (PTS). As described above in FIGS. 4a and 4b, spectrum drift may occur in the plurality of original spectra (SPT1). A spectrum stabilization method to correct this can be performed in the second operation unit (PRC2).

[0112] Referring to FIG. 6, the second operation unit (PRC2) can divide each of the plurality of original spectra (SPT1) into a plurality of energy intervals (SC1, SC2, SC3). The second operation unit (PRC2) can linearly correct each of the plurality of energy intervals (SC1, SC2, SC3). Additionally, the second operation unit (PRC2) can correct the plurality of original spectra (SPT1) by applying a weight different from that of the remaining area (RM) to the peak area (PK) of each of the plurality of original spectra (SPT1). The second operation unit (PRC2) can generate a plurality of corrected spectra (SPT2) through the process described above. The weights applied to the peak area (PK) and the remaining area (RM) are explained in detail in Equation 4. Furthermore, although FIG. 6 illustrates that the spectrum is divided into three energy intervals (SC1, SC2, SC3), the number of energy intervals of the present invention is not limited thereto. The number of energy intervals can be changed as needed.

[0113] In one embodiment of the present invention, the second operation unit (PRC2) may select any one of the plurality of original spectra (SPT1) as a reference spectrum. Additionally, the second operation unit (PRC2) may divide each of the plurality of original spectra (SPT1) into a plurality of energy intervals (SC1, SC2, SC3). Additionally, the second operation unit (PRC2) may calculate a final-correction value that minimizes the value of the objective function for each of the plurality of energy intervals (SC1, SC2, SC3). Furthermore, the second operation unit (PRC2) may generate a plurality of corrected spectra (SPT2) by correcting the plurality of original spectra (SPT1) based on the plurality of final-correction values.

[0114] The objective function may be an equation used to calculate the similarity between the corrected spectrum and the reference spectrum by reflecting the aforementioned weights. For example, a smaller objective function value indicates that the corrected spectrum is more similar to the reference spectrum and that the correction performance based on that value is superior. The objective function is explained in detail in Equation 5.

[0115] In one embodiment of the present invention, the second operation unit (PRC2) can calculate a plurality of objective function values ​​corresponding to a plurality of correction values ​​for each of a plurality of energy ranges. Additionally, the second operation unit (PRC2) can calculate a final-correction value, which is a correction value corresponding to the smallest objective function value among the plurality of objective function values. That is, by substituting a plurality of correction values ​​into the objective function, the second operation unit (PRC2) can calculate a final-correction value that has the best correction performance for a specific energy range.

[0116] In one embodiment of the present invention, the second operation unit (PRC2) can calculate a plurality of objective function values ​​using the following mathematical formulas 1 to 5. Additionally, the second operation unit (PRC2) can generate the plurality of corrected spectra (SPT2) by correcting the plurality of original spectra (SPT1) based on the plurality of final correction values ​​and the following mathematical formulas 1 to 3.

[0117] [Mathematical Formula 1]

[0118]

[0119] Here, k represents the correction value and n represents the energy level.

[0120] [Mathematical Formula 2]

[0121]

[0122] [Mathematical Formula 3]

[0123]

[0124] Here, is the coefficient value of the corrected original spectrum corresponding to energy level n and correction value k, represents the coefficient value of the original spectrum corresponding to the energy level n. Equation 3 may be an equation used to generate a corrected spectrum corresponding to an arbitrary correction value k.

[0125] [Mathematical Formula 4]

[0126]

[0127] (Here, represents the weight corresponding to energy level n, t<1)

[0128] [Mathematical Formula 5]

[0129]

[0130] Here, is the objective function, N is the maximum energy level within the above energy interval, is the coefficient value of the reference spectrum corresponding to energy level n, represents the coefficient value of the corrected spectrum corresponding to the energy level n.

[0131] Referring to mathematical equations 4 and 5, the weight is the objective function It is used to calculate. The objective function value represents the difference between the corrected spectrum and the reference spectrum. For example, the smaller the objective function value, the more similar the corrected spectrum is to the reference spectrum, and it means that the correction performance by any correction value k is excellent.

[0132] Meanwhile, in existing spectrum stabilization methods, weights are applied to all regions of the spectrum It is defined as such. Accordingly, spectra are intensively corrected and optimized for energy levels with high coefficient values. However, this type of spectrum stabilization method is not suitable for application to the process of correcting spectra generated from one-to-one coupled array silicon photomultiplier tubes (OSPs). This is because spectra generated from one-to-one coupled array silicon photomultiplier tubes (OSPs) have high coefficient values ​​in the low-energy region and different statistical distributions. The cause of this phenomenon is Compton scattering and backscattering between multiple scintillator-photosensor assemblies (STRs).

[0133] In this application, to solve this problem, a spectrum stabilization method is designed so that the spectra are corrected and optimized around the peak region by applying a lower weight to the peak region than to the rest of the region (see Equation 4).

[0134] In one embodiment of the present invention, each of the plurality of correction values ​​may be 0.5 or higher and 2.0 or lower. More preferably, each of the plurality of correction values ​​may be 0.6 or higher and 1.4 or lower.

[0135] In one embodiment of the present invention, the second operation unit (PRC2) can calculate a final-corrected value using at least one of a grid search method and an optimization algorithm. By using at least one of a grid search method and an optimization algorithm, the time required to calculate the final-corrected value can be reduced.

[0136] In one embodiment of the present invention, the second operation unit (PRC2) can calculate a final-correction value by applying an arbitrary correction value to the objective function through random sampling and then using a grid search method.

[0137] In another embodiment of the present invention, the second operation unit (PRC2) can calculate a final -correction value by using an optimization algorithm after substituting an arbitrary correction value into the objective function.

[0138] Since the grid search method and optimization algorithm are widely known technologies, they are not described separately in this specification.

[0139] In one embodiment of the present invention, the second operation unit (PRC2) can select a reference spectrum based on the sum of the coefficient values ​​for each energy level, the coefficient value in the peak region, and the resolution of the detector.

[0140] In the present invention, an energy range refers to a partial region corresponding to a specific energy level range within the entire spectrum. For example, when the energy level range of the entire spectrum is 0 to 900 KeV, the first energy range may be a partial region corresponding to 0 to 300 KeV.

[0141] In one embodiment of the present invention, a second operation unit (PRC2) may divide each of the plurality of original spectra (SPT1) into a first energy interval (SC1), a second energy interval (SC2), and a third energy interval (SC3). The maximum energy level of the first energy interval (SC1) may be smaller than the minimum energy level of the second energy interval (SC2). The maximum energy level of the second energy interval (SC2) may be smaller than the minimum energy level of the third energy interval (SC3).

[0142] In another embodiment of the present invention, the number of energy intervals generated by dividing each of the plurality of original spectra (SPT1) may be changed. The number of energy intervals may vary depending on the degree of nonlinearity of the detector (DTT). Preferably, the number of energy intervals may be three. If the number of energy intervals exceeds three, problems may arise such as increased fluctuation of the objective function or the objective function value converging to a local minimum. If the number of energy intervals is less than three, the correction performance for spectra with nonlinear characteristics may be low.

[0143] The third operation unit (PRC3) can perform spectroscopic analysis based on multiple correction spectra (SPT2).

[0144] The display unit (DSP) can provide an image corresponding to at least one of a plurality of original spectra (SPT1) and a plurality of corrected spectra (SPT2) as a result of spectroscopic analysis performed in the third processing unit (PRC3). The display unit may be a device that receives power and displays an image.

[0145] The power supply unit (BTT) can supply power to each component.

[0146] FIG. 7 illustrates a flowchart of a spectrum stabilization method (SSM) for radionuclide analysis according to one embodiment of the present invention. FIG. 8 illustrates a detailed flowchart of a correction value determination step (S430).

[0147] Referring to FIG. 7, the spectrum stabilization method (SSM) for radionuclide analysis may include a scintillation generation step (S100), an electrical signal generation step (S200), an original spectrum generation step (S300), a corrected spectrum generation step (S400), and a spectroscopic analysis performance step (S500).

[0148] In the scintillation generation step (S100), a plurality of scintillators (SCN) can absorb radiation (RDT) in the form of electromagnetic waves to generate scintillations. The description of the plurality of scintillators (SCN) is substantially the same as that described in FIG. 5.

[0149] In the electrical signal generation step (S200), a plurality of optical sensors (PTS) can convert the flashes into an electrical signal (SGN). The plurality of optical sensors (PTS) can correspond one-to-one with a plurality of scintillators (SCN). The description of the plurality of optical sensors (PTS) is substantially the same as that described in FIG. 5.

[0150] In one embodiment of the present invention, each of the plurality of optical sensors (PTS) is a silicon photomultiplier and may include a Geiger-Mode Avalanche Photodiode (GAPD).

[0151] In the original spectrum generation step (S300), the first operation unit (PRC1) can generate a plurality of original spectra (SPT1) based on an electrical signal (SGN). The description of the first operation unit (PRC) is substantially the same as that described in FIG. 5.

[0152] In the correction spectrum generation step (S400), the second operation unit (PRC2) can divide each of the plurality of original spectra (SPT1) into a plurality of energy intervals and linearly correct each of the plurality of energy intervals. Additionally, the second operation unit (PRC2) can correct the plurality of original spectra (SPT1) by applying a weight different from that of the remaining area (RM) to the peak area (PK) of each of the plurality of original spectra (SPT1). The second operation unit (PRC2) can generate a plurality of correction spectra (SPT2) through the above-described process. The description of the second operation unit (PRC2) is substantially the same as that described in FIGS. 5 and 6.

[0153] A correction spectrum generation step (S400) according to one embodiment of the present invention may include a reference spectrum selection step (S410), an energy interval division step (S420), a correction value determination step (S430), and a spectrum correction step (S440). In the reference spectrum selection step (S410), the second operation unit (PRC2) may select any one of a plurality of original spectra (SPT1) as the reference spectrum. In the energy interval division step (S420), the second operation unit (PRC2) may divide each of the plurality of original spectra (SPT1) into a plurality of energy intervals. In the correction value determination step (S430), the second operation unit (PRC2) may calculate a final-correction value that minimizes the value of the objective function for each of the plurality of energy intervals of each of the plurality of original spectra (SPT1). In the spectrum correction step (S440), the second operation unit (PRC2) can correct the plurality of original spectra (SPT1) based on the plurality of final-correction values ​​to generate the plurality of corrected spectra (SPT2).

[0154] In the correction value determination step (S430) according to one embodiment of the present invention, the first spectrum may be any one of a plurality of original spectra (SPT1). The first energy interval may be any one of the plurality of energy intervals of the first spectrum. Additionally, the correction value determination step (S430) may include a step for calculating an objective function value for each correction value (S431), a step for calculating a final correction value for a target interval (S432), and a step for iterative calculation for each energy interval (S433). In the step for calculating an objective function value for each correction value (S431), the second operation unit (PRC2) may calculate a plurality of objective function values ​​corresponding to a plurality of correction values ​​for the first energy interval. In the step for calculating a final correction value for a target interval (S432), the second operation unit (PRC2) may calculate a final correction value, which is a correction value corresponding to the smallest objective function value among the plurality of objective function values. In the iterative calculation step (S433) for each energy interval, the second operation unit (PRC2) can repeatedly perform the objective function value calculation step (S431) for each correction value and the target interval final-correction value calculation step (S432) for each of the multiple energy intervals of each of the multiple original spectra (SPT1).

[0155] In the step (S431) of calculating objective function values ​​for each correction value according to one embodiment of the present invention, the second operation unit (PRC2) can calculate a plurality of objective function values ​​using the following mathematical formulas 1 to 5. In addition, the second operation unit (PRC) can generate a plurality of corrected spectra (SPT2) by correcting a plurality of original spectra (SPT1) based on a plurality of final correction values ​​and the following mathematical formulas 1 to 3.

[0156] [Mathematical Formula 1]

[0157]

[0158] Here, k represents the correction value and n represents the energy level.

[0159] [Mathematical Formula 2]

[0160]

[0161] [Mathematical Formula 3]

[0162]

[0163] Here, is the coefficient value of the corrected original spectrum corresponding to energy level n and correction value k, represents the coefficient value of the original spectrum corresponding to the energy level n. Equation 3 may be an equation used to generate a corrected spectrum corresponding to an arbitrary correction value k.

[0164] [Mathematical Formula 4]

[0165]

[0166] (Here, represents the weight corresponding to energy level n, t<1)

[0167] [Mathematical Formula 5]

[0168]

[0169] Here, is the objective function, N is the maximum energy level within the above energy interval, is the coefficient value of the reference spectrum corresponding to energy level n, represents the coefficient value of the corrected spectrum corresponding to the energy level n.

[0170] Referring to mathematical equations 4 and 5, the weight is the objective function It is used to calculate. The objective function value represents the difference between the corrected spectrum and the reference spectrum. For example, the smaller the objective function value, the more similar the corrected spectrum is to the reference spectrum, and it means that the correction performance by any correction value k is excellent.

[0171] Meanwhile, in existing spectrum stabilization methods, weights are applied to all regions of the spectrum It is defined as such. Accordingly, spectra are intensively corrected and optimized for energy levels with high coefficient values. However, this type of spectrum stabilization method is not suitable for application to the process of correcting spectra generated from one-to-one coupled array silicon photomultiplier tubes (OSPs). This is because spectra generated from one-to-one coupled array silicon photomultiplier tubes (OSPs) have high coefficient values ​​in the low-energy region and different statistical distributions. The cause of this phenomenon is Compton scattering and backscattering between multiple scintillator-photosensor assemblies (STRs).

[0172] In this application, to solve this problem, a spectrum stabilization method is designed so that the spectra are corrected and optimized around the peak region by applying a lower weight to the peak region than to the rest of the region (see Equation 4).

[0173] In the step of calculating the objective function value for each correction value (S431) according to one embodiment of the present invention, each of the plurality of correction values ​​may be 0.5 or higher and 2.0 or lower. More preferably, each of the plurality of correction values ​​may be 0.6 or higher and 1.4 or lower.

[0174] In one embodiment of the present invention, the second operation unit (PRC2) can calculate the final-correction value using at least one of a grid search method and an optimization algorithm. Using at least one of a grid search method and an optimization algorithm can reduce the time required to calculate the final-correction value. In one embodiment of the present invention, the second operation unit (PRC2) can calculate the final-correction value using a grid search method after substituting an arbitrary correction value into the objective function through random sampling.

[0175] In another embodiment of the present invention, the second operation unit (PRC2) can calculate a final -correction value by using an optimization algorithm after substituting an arbitrary correction value into the objective function.

[0176] Since the grid search method and optimization algorithm are widely known technologies, they are not described separately in this specification.

[0177] In the reference spectrum selection step (S410) according to one embodiment of the present invention, the second operation unit (PRC2) can select the reference spectrum based on the total sum of coefficient values ​​by energy level, the coefficient value in the peak region, and the resolution of the detector.

[0178] In the energy interval division step (S420) according to one embodiment of the present invention, the second operation unit (PRC2) may divide each of the plurality of original spectra (SPT1) into a first energy interval (SC1, FIG. 6), a second energy interval (SC2, FIG. 6), and a third energy interval (SC3, FIG. 6). The maximum energy level of the first energy interval (SC1, FIG. 6) may be smaller than the minimum energy level of the second energy interval (SC2, FIG. 6). The maximum energy level of the second energy interval (SC2, FIG. 6) may be smaller than the minimum energy level of the third energy interval (SC3, FIG. 6).

[0179] In another embodiment of the present invention, the number of energy intervals generated by dividing each of the plurality of original spectra (SPT1) may be changed. The number of energy intervals may vary depending on the degree of nonlinearity of the detector (DTT). Preferably, the number of energy intervals may be three. If the number of energy intervals exceeds three, problems may arise such as increased fluctuation of the objective function or the objective function value converging to a local minimum. If the number of energy intervals is less than three, the correction performance for spectra with nonlinear characteristics may be low.

[0180] In the spectroscopic analysis execution step (S500), the third computation unit (PRC3) can perform spectroscopic analysis based on a plurality of correction spectra (SPT2).

[0181] A spectrum stabilization method (SSM) for radionuclide analysis according to one embodiment of the present invention may further include an analysis result display step (not shown). In the analysis result display step (not shown), a display unit (DSP) may provide an image corresponding to at least one of a plurality of original spectra (SPT1) and a plurality of corrected spectra (SPT2) as a result of spectroscopic analysis. The display unit may be a device that receives power and displays an image.

[0182] To summarize the above, the radioactive nuclide analysis process using the present invention is simple in terms of calculation. Therefore, by using the present invention, real-time analysis of radioactive nuclides can be performed even on portable radiation detectors with relatively low computational capabilities.

[0183] FIGS. 9 and FIGS. 10 illustrate exemplary results of correcting the original spectrum using the present invention.

[0184] Referring to FIGS. 9 and 10, it is confirmed that a corrected spectrum similar to the reference spectrum is generated by correcting the original spectrum. In particular, by referring to the peak regions (AA1 to AA6), it is confirmed that the peak positions of the reference spectrum and the corrected spectrum coincide. That is, through the present invention, an original spectrum having a statistical distribution different from the reference spectrum can also be corrected to be similar to the reference spectrum. This is an improvement compared to conventional spectrum stabilization methods, which are applicable only to spectra with identical statistical distributions.

[0185] Figure 11 shows a graph of the relative error between the correction spectrum and the reference spectrum calculated for each of the multiple scintillator-photosensor assemblies through repeated experiments.

[0186] This experiment is intended to compare the correction performance based on conventional spectrum stabilization methods with the correction performance based on the present invention. In this experiment, the aforementioned relative error was repeatedly calculated for each of the multiple scintillator-photosensor assemblies. Additionally, in this experiment, the aforementioned calculation was repeatedly performed for each of the multiple peaks (121 KeV, 344 KeV, 622 KeV, 1170 KeV, 1330 KeV). Each of the multiple peaks corresponds to a specific radionuclide. In this experiment, the radionuclides include europium (Eu), cesium (Cs), and cobalt (Co).

[0187] Specifically, the horizontal axis of each of the graphs shown in FIG. 11 represents the number of multiple scintillator-photosensor assemblies. In this experiment, a silicon photomultiplier tube with an 8x8 array was used. Accordingly, the relative error described above was calculated for each of the total 64 scintillator-photosensor assemblies. In addition, the vertical axis of each of the graphs represents the relative error. A vertical axis value closer to 0 and a shorter vertical axis interval indicates a smaller relative error. Considering this, it can be seen that spectrum stabilization (AA7) using the present invention has superior correction performance compared to spectrum stabilization (AA8) using conventional technology. Therefore, using the present invention allows for more accurate analysis of radionuclides than using conventional technology.

[0188] Although the invention has been described with reference to exemplary embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as set forth in the following claims. Furthermore, the exemplary embodiments disclosed in the invention are not intended to limit the technical spirit of the invention, and all technical spirits within the scope of the following claims and their equivalents should be interpreted as being included within the scope of the rights of the invention. Explanation of the symbols

[0189] LSP: Light-sharing array silicon photomultiplier OSP: One-to-one coupled array silicon photomultiplier DRD: Radiation detection system with spectrum stabilization method SCN: Multiple scintillators LGD: Light guide PTS: Multiple optical sensors STR: Multiple scintillator-optical sensor assemblies DTT: Detector PRC: Calculation Unit DSP: Display unit BTT: Power supply unit

Claims

Claim 1 A spectrum stabilization method for radionuclide analysis comprising: a scintillation generation step in which a plurality of scintillators absorb radiation in the form of electromagnetic waves to generate scintillations; an electrical signal generation step in which a plurality of optical sensors corresponding one-to-one to the plurality of scintillators convert the scintillations into electrical signals; an original spectrum generation step in which a first computing unit generates a plurality of original spectra based on the electrical signals; a correction spectrum generation step in which a second computing unit divides each of the plurality of original spectra into a plurality of energy intervals, linearly corrects each of the plurality of energy intervals, and corrects the plurality of original spectra by setting the weight applied to the peak region of each of the plurality of original spectra to be lower than the weight applied to the remaining region, thereby generating a plurality of corrected spectra; and a spectroscopic analysis execution step in which a third computing unit performs spectroscopic analysis based on the plurality of corrected spectra. Claim 2 A spectrum stabilization method for radionuclide analysis according to claim 1, wherein the correction spectrum generation step comprises: a reference spectrum selection step in which the second operation unit selects one of the plurality of original spectra as a reference spectrum; an energy interval division step in which the second operation unit divides each of the plurality of original spectra into a plurality of energy intervals; a correction value determination step in which the second operation unit calculates a final-correction value that minimizes the value of an objective function for each of the plurality of energy intervals of each of the plurality of original spectra; and a spectrum correction step in which the second operation unit corrects the plurality of original spectra based on the plurality of final-correction values ​​to generate a plurality of correction spectra. Claim 3 A spectrum stabilization method for radionuclide analysis according to claim 2, wherein in the correction value determination step, the first spectrum is any one of the plurality of original spectra and the first energy range is any one of the plurality of energy ranges of the first spectrum, and the correction value determination step comprises: a correction value-specific objective function value calculation step in which the second operation unit calculates a plurality of objective function values ​​corresponding to a plurality of correction values ​​for the first energy range; a target range final-correction value calculation step in which the second operation unit calculates a final-correction value, which is a correction value corresponding to the smallest objective function value among the plurality of objective function values; and an energy range-specific iterative calculation step in which the second operation unit repeatedly performs the objective function value calculation step and the final-correction value calculation step for each of the plurality of original spectra. Claim 4 A spectrum stabilization method for radionuclide analysis according to claim 3, wherein in the step of calculating objective function values ​​for each correction value, the second operation unit calculates the plurality of objective function values ​​using the following mathematical formulas 1 to 5, and in the spectrum correction step, the second operation unit corrects the plurality of original spectra based on the plurality of final correction values ​​and the following mathematical formulas 1 to 3 to generate the plurality of corrected spectra. [Mathematical Formula 1] (Here, k is the correction value, and n represents the energy level)[Equation 2] [Mathematical Formula 3] (Here, is the coefficient value of the corrected original spectrum corresponding to energy level n and correction value k, represents the coefficient value of the original spectrum corresponding to energy level n)[Equation 4] (Here, represents the weight corresponding to the energy level n, t<1)[Equation 5] (Here, is the objective function, N is the maximum energy level within the above energy interval, is the coefficient value of the reference spectrum corresponding to energy level n, represents the coefficient value of the corrected spectrum corresponding to the energy level n) Claim 5 A spectrum stabilization method for radionuclide analysis according to claim 4, wherein in the step of calculating objective function values ​​for each correction value, each of the plurality of correction values ​​is 0.5 or more and 2.0 or less. Claim 6 A spectrum stabilization method for radionuclide analysis according to claim 5, wherein in the iterative calculation step for each interval, the second operation unit calculates the final-corrected value using at least one of a grid search method and an optimization algorithm. Claim 7 A spectrum stabilization method for radionuclide analysis according to claim 2, wherein in the reference spectrum selection step, the second operation unit selects the reference spectrum based on the sum of the coefficient values ​​for each energy level, the coefficient value in the peak region, and the resolution of the detector. Claim 8 A spectrum stabilization method for radionuclide analysis according to claim 2, wherein in the energy interval division step, the second operation unit divides each of the plurality of original spectra into a first energy interval, a second energy interval, and a third energy interval, wherein the maximum energy level of the first energy interval is smaller than the minimum energy level of the second energy interval, and the maximum energy level of the second energy interval is smaller than the minimum energy level of the third energy interval. Claim 9 A spectrum stabilization method for radionuclide analysis according to claim 1, further comprising an analysis result display step, wherein in the analysis result display step, the display unit provides an image corresponding to at least one of the result of the spectroscopic analysis, the plurality of original spectra, and the plurality of corrected spectra. Claim 10 A spectrum stabilization method for radionuclide analysis according to claim 1, wherein each of the plurality of optical sensors is a silicon photomultiplier and includes a Geiger-Mode Avalanche Photodiode (GAPD). Claim 11 A radiation detection system comprising a plurality of scintillators and a plurality of optical sensors, wherein the plurality of scintillators absorb radiation in the form of electromagnetic waves to generate scintillations, and the plurality of optical sensors convert the scintillations into electrical signals; a first computational unit that generates a plurality of original spectra based on the electrical signals; a second computational unit that generates a plurality of corrected spectra by dividing each of the plurality of original spectra into a plurality of energy intervals, linearly correcting each of the plurality of energy intervals, and correcting the plurality of original spectra by setting the weight applied to the peak region of each of the plurality of original spectra to be lower than the weight applied to the remaining region; a third computational unit that performs spectroscopic analysis based on the plurality of corrected spectra; a display unit that provides an image corresponding to at least one of the plurality of original spectra and the plurality of corrected spectra as a result of the spectroscopic analysis; and a power supply unit that supplies power to each component, wherein the plurality of optical sensors are coupled to the lower portion of the plurality of scintillators, and a spectrum stabilization method corresponding one-to-one to the plurality of scintillators is applied. Claim 12 A radiation detection system to which a spectrum stabilization method is applied, wherein the second operation unit selects one of the plurality of original spectra as a reference spectrum, divides each of the plurality of original spectra into a plurality of energy intervals, calculates a final-correction value that minimizes the value of an objective function for each of the plurality of energy intervals, and corrects the plurality of original spectra based on the plurality of final-correction values ​​to generate a plurality of corrected spectra. Claim 13 A radiation detection system to which a spectrum stabilization method is applied, wherein, in claim 12, the second operation unit calculates multiple objective function values ​​corresponding to multiple correction values ​​for each of the multiple energy intervals, and calculates the final-correction value which is the correction value corresponding to the smallest objective function value among the multiple objective function values. Claim 14 A radiation detection system to which a spectrum stabilization method is applied, wherein the second operation unit calculates the plurality of objective function values ​​using the following mathematical formulas 1 to 5, and corrects the plurality of original spectra based on the plurality of final correction values ​​and the following mathematical formulas 1 to 3 to generate the plurality of corrected spectra. [Mathematical Formula 1] (Here, k is the correction value, and n represents the energy level)[Equation 2] [Mathematical Formula 3] (Here, is the coefficient value of the corrected original spectrum corresponding to energy level n and correction value k, represents the coefficient value of the original spectrum corresponding to energy level n)[Equation 4] (Here, represents the weight corresponding to the energy level n, t<1)[Equation 5] (Here, is the objective function, N is the maximum energy level within the above energy interval, is the coefficient value of the reference spectrum corresponding to energy level n, represents the coefficient value of the corrected spectrum corresponding to the energy level n) Claim 15 A radiation detection system to which a spectrum stabilization method is applied, wherein each of the plurality of correction values ​​is 0.5 or more and 2.0 or less in the case of claim 14. Claim 16 In claim 15, the radiation detection system to which a spectrum stabilization method is applied, wherein the second operation unit calculates the final-corrected value using at least one of a grid search method and an optimization algorithm. Claim 17 In claim 12, the radiation detection system to which a spectrum stabilization method is applied, wherein the second operation unit selects the reference spectrum based on the sum of coefficient values ​​by energy level, coefficient values ​​in the peak region, and the resolution of the detector. Claim 18 A radiation detection system according to claim 12, wherein the second operation unit divides each of the plurality of original spectra into a first energy interval, a second energy interval, and a third energy interval, wherein the maximum energy level of the first energy interval is smaller than the minimum energy level of the second energy interval, and the maximum energy level of the second energy interval is smaller than the minimum energy level of the third energy interval, and wherein a spectrum stabilization method is applied. Claim 19 In claim 12, a radiation detection system to which a spectrum stabilization method is applied, wherein each of the plurality of optical sensors is a silicon photomultiplier (SiPM). Claim 20 In claim 19, each of the plurality of optical sensors is a radiation detection system to which a spectrum stabilization method including a GAPD (Geiger-Mode Avalanche Photodiode) is applied.

Images