Method and apparatus for analyzing alpha-emitting radionuclides

Abstract

To provide an analysis method of α-ray emitting nuclides which can detect an abnormality in thin-layer chromatography at an early stage.SOLUTION: An analysis method of α-ray emitting nuclides includes: a separation step of separating α-ray emitting nuclides for each chemical form on a thin-layer plate; an imaging step of repeatedly imaging the thin-layer plate in the process of the separation step; a determination step of determining whether or not the photographed image is within a normal range each time the photographed image is generated in the imaging step; an extraction step of extracting a luminance value of a spot region corresponding to each chemical form of the α-ray emitting nuclide when it is determined that all the photographed images are within the normal range in the determination step; and a specification step of specifying the α-dose corresponding to the luminance value for each chemical form of the α-ray emitting nuclide on the basis of the pre-determined correspondence between the luminance value and the α-dose. At least one of the thin-layer plate and the solvent contains a fluorescent agent that emits visible light when exposed to the α-rays.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for analyzing alpha-emitting radionuclides in a solution.

Background Art

[0002] Radioisotope (RI) therapy can be expected to have a high therapeutic effect by applying various types of RIs to cancer scattered throughout the body or cancer lurking in the body from the inside of the body (see Non-Patent Document 1). Since many of the RI nuclides used in this treatment method emit radiation with a long range, they cause severe damage to healthy cells in internal organs. On the other hand, 211 At emits alpha rays with a short range and has the characteristic of exerting an effect only on cancer without killing cells more than necessary.

[0003] Having such characteristics 211 At is obtained by irradiating a target metal ( 209 Bi, Pb, etc.) with accelerated particles (alpha, 7 Li, etc.) to directly 211 generate At (half-life 7 hours), and then separating At from the target 211 chemically, and 211 synthesizing it as an At solution (see Non-Patent Document 2). And, in order to use this 211 At solution as a drug, it is necessary to accurately examine the amount of At and its chemical state (chemical form) in the solution. 211 224

[0004] As a method for examining the chemical form, thin layer chromatography is generally used. And, as a method for quickly and accurately analyzing the chemical form of 211 At with a short half-life, there is a method of imaging a thin layer plate through an alpha-ray scintillator and specifying the alpha-ray dose for each chemical form from the luminance value of the imaged image (see Patent Document 1 and Non-Patent Document 3).

Prior Art Documents

Patent Documents

[0005] ​[Patent Document 1] Japanese Patent Application Laid-Open No. 2021-21567 [Non-Patent Documents]

[0006] [Non-Patent Document 1] D. Scott. Wilbur, Nature Chemistry, Volume 5, pp 246 (2013) [Non-Patent Document 2] I. Nishinaka, K. Hashimoto, H. Suzuki, Journal of Radioanalytical and Nuclear Chemistry, Volume 318, Issue 2, pp 897-905 (2018) [Non-Patent Document 3] M. Segawa, Journal of Radioanalytical and Nuclear Chemistry, Volume 326, Issue, pp773-778 (2020) [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] In the methods of Patent Document 1 and Non-Patent Document 3, after separating the At solution for each chemical form by thin-layer chromatography, the surface of the dried thin-layer plate can be covered with a protective film and imaged for the first time. Therefore, the progress of thin-layer chromatography cannot be known during the execution. As a result, there is a problem that the time loss becomes large when an abnormality occurs in thin-layer chromatography and it is necessary to start over. 211 Therefore, in view of the above circumstances, the present invention has been made, and its object is to provide a method and an apparatus for analyzing an alpha-emitting nuclide capable of detecting an abnormality at an early stage in the process of analyzing the alpha-ray dose for each chemical form of the alpha-emitting nuclide in a solution by thin-layer chromatography.

[0008] [Means for Solving the Problems]

[0009] One embodiment of the present invention, in order to solve the above problem, is a method for analyzing alpha-emitting radionuclides in a solution, comprising: a separation step of immersing a thin-layer plate on which a solution containing the alpha-emitting radionuclides has been dropped into a solvent to separate the alpha-emitting radionuclides by chemical form; an imaging step of repeatedly imaging the thin-layer plate during the separation step to generate a plurality of imaging images; a determination step of determining whether, each time an imaging image is generated in the imaging step, the imaging image is within a predetermined normal range according to the elapsed time since the start of the separation step; an extraction step of extracting the brightness value of a spot region corresponding to each chemical form of the alpha-emitting radionuclides from the last imaging image if the determination step determines that all of the imaging images are within the normal range; and a identification step of specifying the alpha dose corresponding to the brightness value extracted in the extraction step for each chemical form of the alpha-emitting radionuclides based on a predetermined correspondence between brightness value and alpha dose, wherein at least one of the thin-layer plate and the solvent contains a fluorescent agent that emits visible light when exposed to alpha rays. [Effects of the Invention]

[0010] According to the present invention, abnormalities can be detected early in the process of analyzing the alpha radiation dose for each chemical form of alpha-emitting radionuclides in a solution using thin-layer chromatography. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of an analytical apparatus according to an embodiment of the present invention. [Figure 2] This figure shows a brightness value-alpha dose table. [Figure 3] This is a flowchart of the analysis process. [Figure 4] This figure shows an example of an image captured from a thin-layer plate during the analysis process. [Modes for carrying out the invention]

[0012] Hereinafter, with reference to the drawings, an analytical apparatus 1 according to an embodiment and a method for analyzing alpha-emitting radionuclides using this analytical apparatus 1 will be described. Note that the embodiments of the present invention described below are merely examples of how the present invention can be implemented, and the scope of the present invention is not limited to the scope described in the embodiments. Therefore, the present invention can be implemented by making various modifications to the embodiments.

[0013] Figure 1 is a schematic diagram of an analytical apparatus 1 according to an embodiment of the present invention. The analytical apparatus 1 is an apparatus for analyzing alpha-emitting radionuclides spread out on a thin-layer plate P according to their chemical form. As shown in Figure 1, the analytical apparatus 1 mainly comprises a dark box 2, a container 3, an alpha-ray scintillator 4, an objective lens 5, a high-resolution camera 6, a camera receiver 7, an imaging control unit 8, and an image display unit 9.

[0014] The dark box 2 is a housing that contains the thin-layer plate P, one of the container 3 and the alpha-ray scintillator 4, and the objective lens 5. The dark box 2 is also light-shielded to prevent visible light from entering the internal space. The inner wall of the dark box 2 is painted black to prevent light reflection. The dark box 2 also has a door (not shown) that opens and closes to allow insertion and removal of the thin-layer plate P, container 3, and alpha-ray scintillator 4. Furthermore, an opening is provided on the side of the dark box 2 for connecting the objective lens 5 and the high-resolution camera 6.

[0015] Container 3 is a box-shaped container with an open top and colorless, transparent side walls. As shown in Figure 1(A), container 3 is placed inside the dark box 2. Container 3 contains a thin-layer plate P and a solvent S. Furthermore, container 3 allows visible light emitted from the thin-layer plate P to pass through. The thin-layer plate P is, for example, a plate made of glass or aluminum on which an adsorbent (e.g., silica gel, alumina, cellulose) is fixed in a thin film. The solvent S is, for example, water (H2O) or ethanol (C2H5OH). However, the specific configurations of the thin-layer plate P and solvent S are not limited to the examples described above.

[0016] In this embodiment, at least one of the thin-layer plate P and the solvent S contains a fluorescent agent. For example, the fluorescent agent may be coated on the surface of the thin-layer plate P. Alternatively, the fluorescent agent may be dissolved in the solvent S. The fluorescent agent has the function of emitting visible light when exposed to alpha rays. The specific composition of the fluorescent agent is not particularly limited, but may be, for example, the following.

[0017] Examples of fluorescent agents include ZnSi (manganese-activated zinc silicate) with added Mn, ZnS with added Ag, NaI with added Ti, CsI with added Tl, GAGG and BGO with added Ce, LYSO with added Ce, GSO with added Ce, YAP, CWO, and PWO. Furthermore, Ce, Pr, Ag, Mn, and Eu can be used as additives, and the combinations with the main component are not limited to the examples mentioned above.

[0018] Other examples of fluorescent agents include polystyrene (PS) or polyvinyltoluene (PVT) as a styrene-based base resin to which a first and second phosphor are added. Examples of the first phosphor include 2,5-diphenyloxazole (DPO), 1,4-bis(5-phenyl-2-oxazole)benzene (POPOP), p-tetraphenyl (P-TP), p-quarterphenyl (P-QP), and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (B-PBD). Examples of the second phosphor include bis(O-methylstil)benzene (bis-MSB), 9,10-diphenylanthracene, and 9,10-dimethylanthracene.

[0019] The alpha-ray scintillator 4 selectively converts alpha rays from radiation (alpha rays, beta rays, gamma rays, X-rays, etc.) into visible light, while not converting other types of radiation into visible light. As shown in Figure 1(B), the alpha-ray scintillator 4 is superimposed on a thin-layer plate P erected inside the dark box 2. In other words, the alpha-ray scintillator 4 is interposed between the thin-layer plate P and the objective lens 5. That is, the alpha-ray scintillator 4 plays the role of converting only alpha rays from the radiation emitted from the alpha-emitting radionuclides on the thin-layer plate P into visible light and guiding them to the objective lens 5. A mounting platform (not shown) for erecting the thin-layer plate P may be provided inside the dark box 2.

[0020] The objective lens 5 guides the visible light emitted from the thin plate P inside the dark box 2 to the high-resolution camera 6. The objective lens 5 may have a function to adjust focus and field of view. The high-resolution camera 6 has a photodiode (photoelectric conversion element) that converts the visible light incident through the objective lens 5 into an electrical signal. The high-resolution camera 6 then outputs the electrical signal converted by the photodiode (hereinafter referred to as "image data") to the camera receiver 7. The objective lens 5 and the high-resolution camera 6 are an example of an imaging device.

[0021] As shown in Figures 1(A) and 1(B), the container 3 and the alpha-ray scintillator 4 are selectively placed in the dark box 2 so that they face the objective lens 5. First, as shown in Figure 1(A), the container 3 containing the thin-layer plate P and the solvent S is placed in the dark box 2 so that the thin-layer plate P faces the objective lens 5. Then, as shown in Figure 1(B), after removing the container 3 from the dark box 2, the stacked thin-layer plate P and the alpha-ray scintillator 4 are placed in the dark box 2 so that the alpha-ray scintillator 4 is interposed between the thin-layer plate P and the objective lens 5.

[0022] However, instead of taking the container 3 and the alpha-ray scintillator 4 in and out of the dark box 2, a first dark box 2A containing the container 3 and a second dark box 2B containing the alpha-ray scintillator 4 may be prepared, and the thin-layer plate P may be moved between the first and second dark boxes 2A and 2B.

[0023] The camera receiver 7 receives image data from the high-resolution camera 6 and outputs the received image data to the imaging control unit 8. The imaging control unit 8 controls the operation of the analysis device 1. More specifically, the imaging control unit 8 analyzes the image data acquired through the camera receiver 7. The specific method of analysis will be described later with reference to Figure 3. The imaging control unit 8 also displays the image shown by the image data on the image display unit (display) 9. The camera receiver 7 and the imaging control unit 8 are examples of controllers.

[0024] The controller includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The controller performs the processing described later by having the CPU read and execute program code stored in ROM. RAM is used as a work area when the CPU executes programs.

[0025] However, the specific configuration of the controller is not limited to this and may be implemented using hardware such as ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array).

[0026] The controller is equipped with memory such as ROM, RAM, or HDD (Hard Disk Drive). The memory stores the brightness value-alpha dose table shown in Figure 2 and multiple comparison images shown in the left column of Figure 4.

[0027] Figure 2 shows a brightness value-alpha dose table. The brightness value-alpha dose table shown in Figure 2 is for five types of radioactivity (alpha dose) that have been identified. 211The results of measuring the brightness values ​​by dropping an At sample onto a thin-layer plate and imaging it with analyzer 1 are shown. The large plots "●" in Figure 2 represent the brightness values ​​measured with analyzer 1 shown in Figure 1(A) (i.e., without the alpha-ray scintillator 4). The small plots "·" in Figure 2 represent the brightness values ​​measured with analyzer 1 shown in Figure 1(B) (i.e., with the alpha-ray scintillator 4). Note that only one of the large plots "●" or small plots "·" may be stored in memory.

[0028] As shown in Figure 2, the drops 211 The higher the alpha radiation intensity (alpha dose) of the At solution, the brighter it is (i.e., the higher the luminance). In other words, there is a positive correlation (more specifically, a proportional relationship) between the luminance value and the alpha dose. Note that the correspondence between the luminance value and the alpha dose stored in the controller's memory is not limited to a table format; it may also be in the form of a function that outputs the corresponding alpha dose when a luminance value is input. Furthermore, for the same alpha dose, the luminance value "·" when the alpha-ray scintillator 4 is interposed is higher than the luminance value "●" when the alpha-ray scintillator 4 is not interposed.

[0029] The normal pattern comparison images shown in the left column of Figure 4 are 211 This image shows the normal progress of thin-layer chromatography according to the elapsed time t1 to t6 after immersion of a thin-layer plate P, on which At solution has been dropped into the dropping area A0 (center of the dashed line), in the solvent (i.e., after starting thin-layer chromatography). In other words, when thin-layer chromatography proceeds normally, the region where the fluorescent agent emits visible light (hereinafter referred to as the "luminescence region") extends linearly from the dropping area A0 along the longitudinal direction of the thin-layer plate P.

[0030] Note that the image at elapsed time t1 is the starting point of thin-layer chromatography (i.e., 211The first image corresponds to the image of the thin-layer plate P immediately after the At solution was dropped onto the plate. The second image corresponds to the image of the thin-layer plate P at the completion of thin-layer chromatography. Furthermore, the third images correspond to the images of the thin-layer plate P taken during the progress of thin-layer chromatography. The intervals between elapsed times t1 and t6 may be equal or different.

[0031] Furthermore, as thin-layer chromatography progresses (for example, after elapsed time t4), peaks in the brightness values ​​of visible light emitted from the fluorescent agent appear on the thin-layer plate P. These peaks (regions with higher brightness values ​​than other parts) are separated by chemical form by thin-layer chromatography. 211 Spot regions A1 and A2 are where At exists.

[0032] Next, the analysis process (analysis method) for alpha-emitting radionuclides using the analyzer 1 will be explained with reference to Figures 3 and 4. Figure 3 is a flowchart of the analysis process. Figure 4 shows an example of images taken of the thin-layer plate P at times t1 to t6 during the analysis process.

[0033] First, the worker applies the dropping area A0 of the thin-layer plate P. 211 Add the At solution dropwise. 211 At solution is a solution containing astatine-211 in multiple chemical forms (compositions). Also, 211 At solution, 211 AtO4 - , 211 AtO3 - , 211 At - In addition to these various chemical forms, as well as impurities 207 Including Po. Next, as shown in Figure 1(A), the operator applies to the dripping area A0. 211 A thin-layer plate P on which At solution has been dropped is immersed in solvent S in a container 3 placed in a dark box 2 (S11). The operator then notifies the imaging control unit 8 to start thin-layer chromatography (for example, by pressing the start button). The process in step S11 is a typical thin-layer chromatography and is an example of a separation step.

[0034] The thin-layer plate P is placed in the container 3 with its longitudinal direction aligned with the vertical direction. Furthermore, the liquid level of the solvent S in the container 3 is adjusted to be below the dropping area A0 of the thin-layer plate P. This allows, 211 The At solution moves along the longitudinal direction of the thin-layer plate P through the gaps in the adsorbent by capillary action. As a result, as shown in Figure 4, the luminescent region extends upward along the longitudinal direction of the thin-layer plate P over time.

[0035] A specific example of an alpha-emitting radionuclide is astatine-211. 211 Not limited to At, Actinium-225 ( 225 Ac), Radium-223 ( 223 Ra), Bismuth-212 212 Bi), Bismuth-213 213 Bi), Terbium-149( 149 Tb), Radium-224 224 Ra), Uranium-230 230 U), Thorium-226 ( 226 Th), Thorium-227 227 It may also be Th). Furthermore, the solution to be analyzed may contain one or more alpha-emitting radionuclides.

[0036] Next, the imaging control unit 8 causes the high-resolution camera 6 to image the thin-layer plate P contained in the container 3 (S12). The process in step S12 is an example of an imaging step. The image captured by the high-resolution camera 6 is an example of an image captured. The timing for executing step S12 is predetermined.

[0037] Next, the imaging control unit 8 acquires image data output from the high-resolution camera 6 via the camera receiver 7. The imaging control unit 8 then determines whether the image generated in step S12 falls within a predetermined normal range based on the elapsed time since the start of step S11 (S13). The process in step S13 is an example of a determination step.

[0038] The imaging control unit 8 can, for example, use a well-known image matching technique to compare the captured image generated in the most recent step S12 with a comparison image corresponding to the execution timing of step S12. The imaging control unit 8 then determines that the captured image is within the normal range if the degree of agreement between the captured image and the comparison image is above a threshold, and determines that the captured image is outside the normal range if the degree of agreement between the captured image and the comparison image is below the threshold. In other words, "the captured image is within the normal range" means that the captured image matches the comparison image to such an extent that it can be evaluated that thin-layer chromatography is proceeding normally.

[0039] When thin-layer chromatography proceeds normally, the degree of agreement between the acquired image and the comparison image exceeds a threshold. On the other hand, thin-layer chromatography is... 211 Abnormalities may occur due to chemical factors such as improper adjustment of the concentration or pH of the At solution, or human factors such as operator errors (e.g., incorrect placement of the dropping area A0, incorrect amount of dropping, or mishandling of the thin-layer plate P).

[0040] As a first example, if the thin-layer plate P is tilted in container 3, the luminescent region will be tilted relative to the longitudinal direction of the thin-layer plate P, as shown in abnormal pattern 1. As a second example, if the concentration or pH exceeds the predetermined range... 211 When At solution is dropped onto thin-layer plate P, the dropping area A0 and spot areas A1 and A2 are deformed as shown in abnormal pattern 2. As a third example, 211 If there is too much At solution, bleeding occurs on the thin-layer plate P, as shown in abnormal pattern 3. As a fourth example, if the dropping area A0 is misaligned, the luminescence area will also be misaligned, as shown in abnormal pattern 4.

[0041] Next, if the imaging control unit 8 determines that the captured image is within the normal range (S13: Yes), it determines whether or not thin-layer chromatography is complete (S14). Whether or not thin-layer chromatography is complete can be determined, for example, by the time a predetermined period of time (for example, 1 hour) has elapsed since the start of step S11. If the imaging control unit 8 determines that thin-layer chromatography is not complete (S14: No), it executes the processes of steps S12 to S13 again. In other words, the imaging control unit 8 repeatedly executes the processes of steps S12 to S13 until thin-layer chromatography is completed.

[0042] Furthermore, if the imaging control unit 8 determines that the captured image is outside the normal range (S13: No), it will repeat the process in step S11. The imaging control unit 8 may, for example, display on the image display unit 9 that an abnormality has occurred in the thin-layer chromatography and prompt the operator to repeat the process in step S11.

[0043] Furthermore, when the imaging control unit 8 determines that all captured images are within the normal range and that thin-layer chromatography is complete (S13: Yes & S14: Yes), it notifies the operator of the completion of thin-layer chromatography via the image display unit 9. The operator removes the thin-layer plate P from the container 3, dries it, and covers it with a protective film (S15). Next, as shown in Figure 1(B), the operator removes the container 3 from the dark box 2 and places the stacked thin-layer plate P and alpha-ray scintillator 4 into the dark box 2.

[0044] 211 Since the distance that At solution travels differs depending on the chemical form, as shown in the lower left example of Figure 4, it travels to different spot regions A1 and A2 on the thin-layer plate P. 211 At is separated (decomposed) according to its chemical form. Then, the imaging control unit 8 causes the high-resolution camera 6 to image the thin-layer plate P on which the alpha-ray scintillators 4 are stacked (S16). The process in step S16 is an example of the final imaging step.

[0045] Next, the imaging control unit 8 acquires image data output from the high-resolution camera 6 via the camera receiver 7. Then, the imaging control unit 8 processes the acquired image data, 211 The brightness values ​​for spot regions A1 and A2 corresponding to each chemical form of At are extracted (S17). The process in step S17 is an example of an extraction step.

[0046] Next, the imaging control unit 8 identifies the alpha dose corresponding to the brightness values ​​of spot regions A1 and A2 based on the brightness value-alpha dose table (S18). That is, the imaging control unit 8 identifies the alpha dose corresponding to the brightness values ​​extracted in step S17. 211 Identify each chemical form of At. The process in step S18 is an example of an identification step.

[0047] The imaging control unit 8 may, for example, display the image captured in step S16 and the alpha dose for each chemical form identified in step S18 on the image display unit 9, in correspondence with each other. 211 Since the alpha dose per unit amount of At is constant, the imaging control unit 8, for example, based on the alpha dose for each chemical form identified in step S18, 211 The proportion (amount produced) of each chemical form contained in the At solution may also be specified.

[0048] According to the above embodiment, for example, the following effects are achieved.

[0049] According to the above embodiment, by including a fluorescent agent in at least one of the thin-layer plate P and the solvent S, during the progress of thin-layer chromatography... 211 The separation status of the At solution can be visualized. This allows for the detection of an anomaly at elapsed time t2 in anomaly pattern 1 of Figure 4, and at elapsed time t1 in anomaly patterns 2-4 of Figure 4. On the other hand, the method in Patent Document 1 requires visualization until thin-layer chromatography is completed (i.e., until elapsed time t6). 211 The separation status of the At solution cannot be visualized. In other words, according to the analytical process shown in Figure 3, anomalies in thin-layer chromatography can be detected earlier compared to conventional methods.

[0050] Furthermore, as shown in Figure 2, the brightness value corresponding to the same alpha dose is higher when the alpha-ray scintillator 4 is interposed. Therefore, according to the above embodiment, the thin-layer plate P is imaged through the alpha-ray scintillator 4 in the final imaging step (S16), and the alpha dose is determined based on the small plot "·" in Figure 2, thereby allowing for the accurate determination of the alpha dose for each chemical form in step S18.

[0051] However, instead of steps S15 to S16, the thin-layer plate P while it is housed in container 3 may be imaged, and the alpha dose may be determined based on the large plot "●" in Figure 2. This eliminates the need to dry the thin-layer plate P or replace container 3 and alpha-ray scintillator 4, thereby reducing the risk of operational errors and radiation exposure.

[0052] Furthermore, the process in step S13 of Figure 3 is not limited to being performed by the imaging control unit 8 of the analyzer 1, but may also be performed visually by an operator. For example, the operator may compare the captured image displayed on the image display unit 9 with a pre-prepared comparison image to determine whether or not it is within the normal range. Also, the processes in steps S17 to S18 of Figure 3 are not limited to being performed by the imaging control unit 8 of the analyzer 1, but may also be performed visually by an operator. For example, the operator may compare the captured image displayed on the image display unit 9 with pre-prepared samples of brightness values ​​for each alpha dose to identify the alpha dose for each chemical form. Moreover, this analyzer 1 and analysis method can be applied not only in the medical field but also as an analytical technique in basic chemistry.

[0053] Although embodiments of the present invention have been described above, the conditions in the examples are merely one example of conditions adopted to confirm the feasibility and effectiveness of the present invention, and the present invention is not limited to this one example of conditions. The present invention can adopt various conditions as long as they do not depart from the spirit of the invention and achieve the objectives of the present invention. [Explanation of symbols]

[0054] 1…Analytical device, 2…Dark box, 3…Container, 4…Alpha-ray scintillator, 5…Objective lens, 6…High-resolution camera, 7…Camera receiver, 8…Imaging controller, 9…Image display unit

Claims

1. A method for analyzing alpha-emitting radionuclides in solution, A separation step involves immersing a thin-layer plate, to which a solution containing the alpha-emitting radionuclides has been dropped, in a solvent to separate the alpha-emitting radionuclides according to their chemical form. The imaging step involves repeatedly imaging the thin-layer plate during the separation step to generate multiple images, Each time the captured image is generated in the imaging step, a determination step is performed to determine whether the captured image is within a predetermined normal range according to the elapsed time since the start of the separation step. If the determination step determines that all the captured images are within the normal range, the extraction step involves extracting the brightness values ​​of the spot regions corresponding to each chemical form of the alpha-emitting nuclide from the last captured image. The process includes a selection step in which, based on a predetermined correspondence between brightness values ​​and alpha doses, the alpha doses corresponding to the brightness values ​​extracted in the extraction step are identified for each chemical form of the alpha-emitting nuclide. A method for analyzing alpha-emitting radionuclides, characterized in that at least one of the thin-layer plate and the solvent contains a fluorescent agent that emits visible light when exposed to alpha rays.

2. In the method for analyzing alpha-emitting radionuclides according to claim 1, A method for analyzing alpha-emitting radionuclides, characterized in that if the determination step determines that the captured image is outside the normal range, the separation step is performed again.

3. In the method for analyzing alpha-emitting radionuclides according to claim 1, A method for analyzing alpha-emitting radionuclides, characterized in that, in the final imaging step, the thin-layer plate is imaged via an alpha-ray scintillator that selectively converts alpha rays from radiation into visible light.

4. In the method for analyzing alpha-emitting radionuclides according to claim 1, A method for analyzing alpha-emitting radionuclides, characterized in that the fluorescent agent is Mn-added ZnSi, Ag-added ZnS, Ti-added NaI, Tl-added CsI, Ce-added GAGG, BGO, Ce-added LYSO, Ce-added GSO, YAP, CWO, or PWO.

5. In the method for analyzing alpha-emitting radionuclides according to claim 1, The alpha-emitting nuclide is 211 At, 225 Ac, 223 Ra, 212 Bi, 213 Bi, 149 Tb, 224 Ra, 230 U, 226 Th, 227 A method for analyzing an alpha-emitting nuclide, characterized in that it is any one of Th.

6. An analytical device for analyzing alpha-emitting radionuclides in solution, A dark box containing a container for separating the alpha-emitting radionuclides by chemical form by immersing a thin-layer plate, to which a solution containing the alpha-emitting radionuclides has been dropped, in a solvent, An imaging device that images the thin-layer plate housed in the container inside the dark box and generates an image; The imaging device comprises a controller that analyzes a plurality of the captured images repeatedly generated by the imaging device, The aforementioned controller, Each time the imaging device generates the image, it is determined whether the image is within a predetermined normal range based on the elapsed time since the start of separation of each chemical form of the alpha-emitting nuclide. If all of the aforementioned captured images are determined to be within the normal range, the brightness values ​​of the spot regions corresponding to each chemical form of the alpha-emitting nuclide are extracted from the last captured image. Based on the pre-determined correspondence between brightness values ​​and alpha doses, the alpha dose corresponding to the extracted brightness value is identified for each chemical form of the alpha-emitting nuclide. An analytical apparatus characterized in that at least one of the thin-layer plate and the solvent contains a fluorescent agent that emits visible light when exposed to alpha rays.

Images