Method and apparatus for analyzing radioisotopes

Abstract

To provide a radioisotope analysis method capable of precisely analyzing radiation dose by the chemical form of radioisotope over a long period.SOLUTION: The radioisotope analysis method includes: a separation step of separating radioisotope by chemical form (S11); an imaging step of imaging a thin layer plate via a visualization scintillator and a standard light scintillator that emits standard light (S12); an extraction step of extracting the luminance value of the spot area and the area of the standard light scintillator (S13); a correction step of correcting the luminance value of the spot area based on the standard luminance value and the extracted luminance value (S14); and an identification step of identifying the radiation dose corresponding to the luminance value of the spot area corrected in the correction step based on the previously determined correspondence between the radioisotope luminance values and the radiation doses (S15).SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for analyzing a radioisotope in a solution. [Background technology]

[0002] Radioisotopes (RIs) that emit radiation (such as α-particles, β-particles, and γ-particles) are produced by irradiation in accelerators or nuclear reactors, and then chemically separated to be used in basic research, preclinical research (see Non-Patent Documents 1 and 2), clinical treatment, and industrial applications.

[0003] Here, accurate investigation of the stability of the radiation dose (radioactivity) and chemical state (chemical form) emitted from RI or RI compounds is essential for carrying out the above-mentioned research and industrial applications using RI, and for reducing the risk of exposure to workers who handle RI. Therefore, a patent application has been filed for a new method for simultaneously and quickly analyzing the radiation dose and chemical form emitted from RI (see Patent Document 1), and a paper has been published (see Non-Patent Document 3).

[0004] In the methods of Patent Document 1 and Non-Patent Document 3, radiation emitted from RI separated by chemical form by thin-layer chromatography is visualized by an imaging system consisting of a scintillator and a high-sensitivity camera, and the radiation dose for each chemical system is specified from the relationship between the brightness value and radiation dose obtained in advance. This allows quantitative evaluation of radiation dose in a time about 1 / 100th of the conventional time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-021567 [Non-patent literature]

[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 [Problem to be solved by the invention]

[0007] When the above-mentioned imaging system is operated for a long period of time, the sensitivity to radiation dose changes (hereinafter referred to as "sensitivity deviation") due to deterioration of the camera sensor, dirt on the scintillator surface, etc. (hereinafter referred to as "deterioration over time"). In other words, there is a problem that the accuracy of identifying the radiation dose decreases over time.

[0008] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a method and apparatus for analyzing radioisotopes that can accurately analyze the radiation dose of each chemical form of a radioisotope in a solution over a long period of time. [Means for solving the problem]

[0009] In one embodiment of the present invention, in order to solve the above-mentioned problems, there is provided a method for analyzing a radioisotope in a solution, the method including: a separation step of dropping a solution containing a radioisotope onto a thin layer plate and separating the radioisotope into its chemical form by thin layer chromatography; an imaging step of imaging the thin layer plate via a visualization scintillator that converts radiation into visible light and imaging a standard optical scintillator that emits a predetermined amount of standard light; an extraction step of extracting, from the image captured in the imaging step, luminance values ​​of spot regions corresponding to each chemical form of the radioisotope and extracted luminance values ​​of the region of the standard optical scintillator; a correction step of correcting the luminance value of the spot region based on the standard luminance value corresponding to the standard light and the extracted luminance value extracted in the extraction step; and an identification step of identifying a radiation dose corresponding to the luminance value of the spot region corrected in the correction step, based on a predetermined correspondence relationship between the luminance value of the radioisotope and a radiation dose. Effect of the Invention

[0010] According to the present invention, the radiation amount of each chemical form of a radioisotope in a solution can be accurately analyzed over a long period of time. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram of an analysis device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a two-dimensional image obtained by an analysis device. [Diagram 3] 3 is a table showing the luminance values ​​of areas 1 to 10 in FIG. 2. [Figure 4] FIG. 1 is a diagram showing the correspondence relationship between the luminance values ​​and the radiation doses in regions 1 to 9. [Diagram 5] 1 is a diagram showing the correspondence relationship between the luminance value of an area 10 and the exposure time. [Figure 6] 13 is a flowchart of an analysis process. [Figure 7] FIG. 2 shows a thin layer plate P at each step of the analytical process. [Figure 8]4 is a table showing the results of correcting the luminance values ​​of areas 1 to 9 in FIG. [Figure 9] FIG. 13 is a diagram showing the correspondence relationship between the luminance value corrected by correction method 1 and the radiation dose. [Figure 10] FIG. 13 is a diagram showing the correspondence relationship between the luminance value corrected by correction method 2 and the radiation dose. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an analysis device 1 according to an embodiment and a method for analyzing a radioisotope using the analysis device 1 will be described with reference to the drawings. Note that the embodiment of the present invention described below shows an example of how the present invention is embodied, and the scope of the present invention is not limited to the scope of the embodiment. Therefore, the present invention can be implemented by making various modifications to the embodiment.

[0013] Fig. 1 is a schematic diagram of an analytical device 1 according to an embodiment of the present invention. The analytical device 1 is a device that analyzes radioisotopes spread by chemical form on a thin layer plate P. As shown in Fig. 1, the analytical device 1 mainly includes a dark box 2, a mounting table 3, a visualization scintillator 4, an objective lens 5, a high-sensitivity camera 6, a camera receiver 7, an imaging controller 8, an image display 9, and a standard optical scintillator 10.

[0014] The dark box 2 is a housing that houses the thin layer plate P, the mounting table 3, the visualization scintillator 4, the objective lens 5, and the standard light scintillator 10. The dark box 2 is light-shielded to prevent visible light from entering the internal space. The inner walls of the dark box 2 are painted black to prevent light reflection. The dark box 2 also has a door (not shown) that is opened and closed to insert and remove the thin layer plate P. Furthermore, an opening is provided on the top surface of the dark box 2 for connecting the objective lens 5 and the high-sensitivity camera 6.

[0015] The mounting table 3 is placed on the bottom wall of the dark box 2 in the internal space of the dark box 2. The thin layer plate P, which is the object to be measured, and the standard optical scintillator 10 are placed on the mounting table 3. The mounting table 3 is configured so that the height of the mounting surface for the thin layer plate P and the standard optical scintillator 10 can be adjusted. In other words, the mounting table 3 is configured so that the distance between the thin layer plate P and the standard optical scintillator 10 and the objective lens 5 can be adjusted. The height of the mounting surface may be adjusted manually or by a motor (not shown) that operates according to instructions from the imaging controller 8.

[0016] The visualization scintillator 4 converts radiation into visible light. The visualization scintillator 4 is superimposed on the thin plate P on the mounting table 3. In other words, the visualization scintillator 4 is interposed between the thin plate P on the mounting table 3 and the objective lens 5. The visualization scintillator 4 may be, for example, an α-ray scintillator that selectively converts α-rays, among radiation (α-rays, β-rays, γ-rays, X-rays, etc.), into visible light and does not convert other radiation into visible light. In other words, the visualization scintillator 4 may be one that converts only α-rays, among radiation emitted from a radioisotope on the thin plate P, into visible light and guides it to the objective lens 5.

[0017] The objective lens 5 guides the visible light emitted from the visualization scintillator 4 and the standard light emitted from the standard light scintillator 10 to the high-sensitivity camera 6. The objective lens 5 may have a function of adjusting the focus and angle of view. The high-sensitivity 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-sensitivity camera 6 then outputs the electrical signal (hereinafter referred to as "image data") converted by the photodiode to a camera receiver 7. The objective lens 5 and the high-sensitivity camera 6 are an example of an imaging device.

[0018] The camera receiver 7 receives image data from the high-sensitivity camera 6 and outputs the received image data to the imaging controller 8. The imaging controller 8 controls the operation of the analysis device 1. More specifically, the imaging controller 8 analyzes the image data acquired through the camera receiver 7. A specific method of analysis will be described later with reference to FIG. 6. The imaging controller 8 also causes an image represented by the image data to be displayed on an image display device (display) 9. The camera receiver 7 and the imaging controller 8 are examples of a controller.

[0019] The standard optical scintillator 10 is placed on the mounting table 3 at a position different (adjacent) to the thin plate P. Furthermore, the standard optical scintillator 10 may be removable from the mounting table 3 as necessary. The standard optical scintillator 10 emits a predetermined amount of light (hereinafter referred to as "standard light"). The standard light emitted from the standard optical scintillator 10 enters the objective lens 5 without passing through the visualization scintillator 4.

[0020] The standard optical scintillator 10 is required to stably emit the same amount of standard light for a long period of time. 1.9 Y 0.1 The LYSO crystal may be composed of SiO5. The LYSO crystal is 176 Lu constantly emits weak light due to X-rays of 600 keV or less emitted by Lu, and is therefore suitable as the standard optical scintillator 10. However, specific examples of the standard optical scintillator 10 are not limited to LYSO crystals. As another example, the standard optical scintillator 10 may be composed of a scintillator material that contains RI and emits light by itself, or by combining a substance or device that emits radiation with a visualization scintillator. As yet another example, the standard optical scintillator 10 may be composed of an LED lamp, halogen, metal halide, incandescent bulb, or laser.

[0021] The controller includes, for example, a central processing unit (CPU), a read only memory (ROM), and a random access memory (RAM). The controller realizes the processes described below by the CPU reading and executing program codes stored in the ROM. The RAM is used as a work area when the CPU executes the programs.

[0022] However, the specific configuration of the controller is not limited to this, and may be realized by hardware such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

[0023] The controller is equipped with a ROM, RAM, or HDD (Hard Disk Drive), which are examples of memory. The memory stores a previously determined correspondence between the luminance value of the radioisotope to be analyzed and the radiation dose, and a standard luminance value corresponding to the standard light. In order to identify the information to be stored in the memory, a quantitative demonstration experiment was carried out in the Hot Chemistry Room of the Tandem Accelerator Facility of the Japan Atomic Energy Agency.

[0024] More specifically, using a tandem accelerator 211 At solution was produced and chemically separated using a dry chemical separation method. 211 A calibration sample is used to calibrate the brightness of an image by dropping At solution onto nine locations on a thin layer plate. 211 A sample of At was prepared. 211 The At sample was imaged by the analysis device 1, and the obtained 2D image was analyzed. 211 The radiation dose of the At solution is assumed to be known.

[0025] FIG. 2 is a diagram showing a two-dimensional image obtained by the analysis device 1. More specifically, FIG. 2(A) is a photograph taken by a high-sensitivity camera 6 of a thin-layer plate P on which a visualization scintillator 4 is laminated, and a standard optical scintillator 10. FIG. 2(B) is a schematic diagram showing regions 1 to 21 in the image of FIG. 2(A). FIG. 3 is a table showing the luminance values ​​of regions 1 to 10 in FIG. 2. FIG. 4 is a diagram showing the correspondence between the luminance values ​​of regions 1 to 9 and the radiation dose. FIG. 5 is a diagram showing the correspondence between the luminance value of region 10 and the exposure time.

[0026] As shown in FIG. 2(A), when the thin plate P is imaged through the visualization scintillator 4, 211 Areas 1 to 9 where the At solution was dropped (hereinafter referred to as "plot areas") appear to be shiny. 211 The higher the radiation dose (α dose) of the At solution, the brighter it is (i.e., the higher the brightness).

[0027] Moreover, region 10 is an imaged portion of the region of the standard optical scintillator 10. Since the amount of standard light emitted from the standard optical scintillator 10 is constant, the luminance value of region 10 will be the same if the imaging conditions of the high-sensitivity camera 6 (for example, exposure time, gain (internal amplification factor), increase or decrease in dark current due to the temperature of the camera sensor, distance between the sample and the camera sensor, background light entering the dark box 2, etc.) are the same and there is no deterioration over time of the analytical device 1.

[0028] Furthermore, regions 11 to 20 are 211 This is a background region where no At solution has been dropped and no standard optical scintillator 10 is placed. That is, the luminance values ​​of the background regions 11-20 are due to background light entering the dark box 2, camera sensor noise, and the like. On the other hand, region 21 is a region for an experiment with a purpose other than that of the present application, and therefore description thereof will be omitted in this specification.

[0029] When the image in FIG. 2(A) is captured under different imaging conditions 1 to 4, and the brightness values ​​of regions 1 to 10 are extracted from the captured image, the result is as shown in FIG. 3. In imaging condition 1, the exposure time is 30 seconds and the gain is 16 times. In imaging condition 2, the exposure time is 50 seconds and the gain is 16 times. In imaging condition 3, the exposure time is 200 seconds and the gain is 16 times. In imaging condition 4, the exposure time is 300 seconds and the gain is 1 times.

[0030] 3 is calculated by {average luminance value of region x-average luminance value of region (x+10)} x the number of pixels in region x, where x is an integer between 1 and 10. That is, when calculating the luminance value of region 1 under imaging condition 1, the average luminance value of regions 1 and 11 is calculated, the average luminance value of region 11 is subtracted from the average luminance value of region 1, and the result is multiplied by the number of pixels in region 1 to calculate the luminance value of region 1 (=1808). The same applies to the luminance values ​​of regions 2 to 10.

[0031] The luminance value is a dimensionless value obtained by multiplying a predetermined gradation (e.g., 8 bits=256 gradations) of each pixel constituting an image by the number of pixels in the corresponding region and the gain of the corresponding imaging conditions. The number of pixels and imaging conditions of regions 1 to 10 are assumed to be stored in memory in advance.

[0032] As shown in Fig. 4, when the luminance values ​​and radiation doses of spot areas 1 to 9 shown in Fig. 3 are plotted, the luminance value of the same spot area (i.e., the same radiation dose) differs depending on the imaging conditions. More specifically, the luminance value in the same spot area increases as the exposure time increases and increases as the gain increases. The plot "□" corresponds to imaging condition 1, the plot "△" corresponds to imaging condition 2, the plot "×" corresponds to imaging condition 3, and the plot "●" corresponds to imaging condition 4.

[0033] As is clear from Fig. 4, there is a positive correlation (more specifically, a linear relationship) between the luminance value and the radiation dose in any of the imaging conditions 1 to 4. The memory of the controller stores the correspondence relationship between the luminance value and the radiation dose shown in Fig. 4. Note that the memory may store a plurality of correspondence relationships corresponding to a plurality of imaging conditions, respectively, or may store only a single correspondence relationship. The correspondence relationship between the luminance value and the radiation dose stored in the memory may be in the form of a table, or may be in the form of a function (typically a linear function) in which a corresponding radiation dose is output when a luminance value is input.

[0034] As shown in Fig. 5, it can be seen that there is a positive correlation (more specifically, a linear relationship) between the luminance value of the region 10 imaged under imaging conditions 1 to 3 and the exposure time. In other words, the luminance value and exposure time of the region 10 under imaging conditions 1 to 3 can be approximated by a linear function shown by the dashed line. Note that in Fig. 5, the plot under imaging condition 4 deviates from the approximation line, but if the gain is the same (i.e., the luminance value is multiplied by 16), it is located near the approximation line.

[0035] The memory of the controller stores the standard luminance value of the standard optical scintillator 10 (more specifically, the predetermined correspondence between a plurality of standard luminance values ​​and exposure times). The standard luminance value is a luminance value that corresponds to the amount of standard light emitted from the standard optical scintillator 10. In other words, the standard luminance value is a luminance value extracted from the region 10 in a state where there is no deterioration over time of the analysis device 1. The predetermined correspondence between the plurality of standard luminance values ​​and exposure times corresponds to, for example, an approximation line (linear function equation) shown in FIG. 5.

[0036] Next, an analytical process (analysis method) of a radioisotope using the analysis device 1 will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a flowchart of the analytical process. Fig. 7 is a diagram showing the thin layer plate P in each step of the analytical process.

[0037] First, as shown in the upper part of Figure 7, at the origin O on the thin plate P, 211The At solution is dropped onto the thin-layer plate P. The thin-layer plate P is a plate made of glass, aluminum, or the like, on which an adsorbent (for example, silica gel, alumina, or cellulose) is fixed in the form of a thin film. 211 The At solution is a solution containing astatine-211 in multiple chemical forms (compositions). 211 At solution is 211 AtO4 - , 211 AtO3 - , 211 At - In addition to the various chemical forms such as 207 Including Po.

[0038] A specific example of a radioisotope (radioactive nuclide) is astatine-211( 211 At), but also 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 Th), hydrogen-3( 3 H), Beryllium-7( 7 Be), Carbon-11( 11 C), carbon-14( 14 C), nitrogen-13( 13 N), Fluorine-18( 18 F), oxygen-15( 15 O), sodium-24( 24 Na), Magnesium-28( 28 Mg), Chlorine-38( 38 Cl), potassium-38( 38 K), Chlorine-39( 39 Cl), potassium-42( 42 K), potassium-43( 43 K), Scandium-43( 43 Sc), Scandium-44( 44 Sc), Scandium-46(46 Sc), Scandium-47( 47 Sc), Titanium-44 ( 44 Ti), Vanadium-48( 48 V), Iron-55( 55 Fe), Cobalt-56( 56 Co), Cobalt-57( 57 Co), Cobalt-58( 58 Co), Nickel-57( 57 Ni), Copper-60( 60 Cu), Copper-61( 61 Cu), Zinc-62( 62 Zn), copper-64( 64 Cu), Copper-67( 67 Cu), Germanium-68( 68 Ge), Gallium-67( 67 Ga), Gallium-68( 68 Ga), Arsenic-74( 74 As), Bromine-76( 76 Br), Krypton-81 ( 81 Kr), Rubidium-81 ( 81 Rb), Rubidium-82( 82 Rb), Rubidium-83( 83 Rb), Rubidium-84 ( 84 Rb), Rubidium-86( 86 Rb), Yttrium-86( 86 Y), Yttrium-87( 87 Y), Yttrium-90 ( 90 Y), Strontium-89 ( 89 Sr), Zirconium-88( 88 Zr), Zirconium-89( 89 Zr), Zirconium-95( 95 Zr), Niobium-90 ( 90 Nb), Niobium-91( 91 Nb), Niobium-92( 92 Nb), Niobium-95( 95 Nb), Molybdenum-93( 93 Mo), Molybdenum-99( 99 Mo), Technetium-93 ( 93 Tc), Technetium-94 ( 94Tc), Technetium-95 ( 95 Tc), Technetium-96 ( 96 Tc), Technetium-99 ( 99 Tc), Cadmium-107( 107 Cd), Indium-111( 111 In), Antimony-124( 124 Sb), Tellurium-121( 121 Te), Iodine-123( 123 I), iodine-124( 124 I), iodine-125( 125 I), iodine-131( 131 I), Cesium-127( 127 Cs), Cesium-132( 132 Cs), Cesium-136( 136 Cs), Lanthanum-135( 135 La), Barium-140 ( 140 Ba), Cerium-139( 139 Ce), Neodymium-141( 141 Nd), Promethium-143( 143 Pm), Promethium-148( 148 Pm), Europium-145( 145 Eu), Europium-148( 148 Eu), Samarium-153( 153 Sm), Terbium-161 ( 161 Tb), Holmium-166( 166 Ho), Ytterbium-167( 167 Yb), Ytterbium-169( 169 Yb), Lutetium-171( 171 Lu), Lutetium-177( 177 Lu), Hafnium-171( 171 Hf), Hafnium-172( 172 Hf), Hafnium-173( 173 Hf), Hafnium-175( 175 Hf), Tantalum-169( 169 Ta), Tantalum-177( 177 Ta), Tantalum-178( 178 Ta), Tantalum-179( 179 Ta), Tungsten-177(177 W), Tungsten-178( 178 W), Tungsten-179( 179 W), Tungsten-181( 181 W), Rhenium-180 ( 180 Re), rhenium-183( 183 Re), rhenium-184( 184 Re), rhenium-186( 186 Re), rhenium-188( 188 Re), Shirogane-188( 188 Pt), Platinum-191( 191 Pt), Iridium-192( 192 Ir), Gold-195( 195 Au), Gold-196( 196 Au), Gold-198( 198 Au), Thallium-201( 201 Tl), Thallium-202 ( 202 Tl), Lead-201( 201 Pb), Lead-203( 203 Pb), Bismuth-207( 207 Bi), Astatine-207( 207 At), astatine-210( 210 At), Francium-213( 213 Fr), Neptunium-238( 238 Np), Uranium-235( 235 U), Mendelevium-255( 255 Md) and the like.

[0039] In addition, among radioisotopes, 211 The At solution is an example of an α-ray emitting nuclide that emits α-rays. The solution to be analyzed may contain one or more types of radioisotopes. The solution of radioisotopes dropped onto the thin layer plate P may contain a single radioisotope or a compound of radioisotopes.

[0040] Next, a drop was dropped at the origin O of the thin plate P. 211 The At solution moves through the gaps in the adsorbent by capillary action. 211Since the distance traveled by each chemical form of At is different, as shown in the middle part of Figure 7, the following three spots are placed on the thin layer plate P: A1, A2, and A3. 211 At is separated (developed) into each chemical form (S11). The process of step S11 is a typical thin layer chromatography, and is an example of a separation step.

[0041] In this example, in spot area A1 211 AtO4 - But in spot area A2 211 AtO3 - But in spot area A3 211 At - is located. 207 Po: 211 AtO4 - and is located in the spot area A1. 211 It is previously determined in which spot area A1 to A3 each chemical form of the At solution is located. 211 At this point, the At solution is colorless and transparent, so 211 It is not possible to visually confirm that the At solutions are separated into their chemical forms.

[0042] next, 211 The thin layer plate P in which the At solution has been separated into its chemical forms is placed on the mounting table 3, and the visualization scintillator 4 is placed on top of it. Next, the focus and angle of view are adjusted by one or both of the mounting table 3 and the objective lens 5. Then, the imaging controller 8 causes the high-sensitivity camera 6 to capture an image of the thin layer plate P and the standard optical scintillator 10 via the visualization scintillator 4 (S12). The process of step S12 is an example of an imaging step.

[0043] The imaging controller 8 may, for example, 211 The exposure time (imaging time) of the high-sensitivity camera 6 may be adjusted according to the concentration of the At solution. 211 The higher the concentration of the At solution, the shorter the exposure time. 211 The lower the concentration of the At solution, the longer the exposure time may be The exposure time of the high-sensitivity camera 6 is appropriately adjusted within the range of, for example, several milliseconds to several thousand seconds.

[0044] As shown in the lower part of Fig. 7, each of the spot regions A1 to A3 in the image shown by the image data has a different brightness (luminance value) according to the radiation emitted by the corresponding chemical form. In the lower part of Fig. 7, the brightness is expressed by the density of dots. That is, the lower the dot density, the brighter the image, and the higher the dot density, the darker the image. In other words, the spot region A2 is the brightest and the spot region A1 is the darkest.

[0045] Next, the imaging controller 8 acquires image data output from the high-sensitivity camera 6 through the camera receiver 7. Then, the imaging controller 8 performs image processing on the acquired image data to obtain the following: 211 The luminance values ​​of the spot regions A1 to A3 corresponding to each chemical form of At and the extracted luminance values ​​of the region of the standard scintillator 10 are extracted (S13). The method of extracting the luminance values ​​is similar to the method described with reference to Fig. 2 and Fig. 3. The process of step S13 is an example of an extraction step.

[0046] Next, the imaging controller 8 corrects (normalizes) the luminance value of each of the spot areas A1 to A3 extracted in step S13 based on the standard luminance value stored in the memory and the extracted luminance value extracted in step S13 (S14). More specifically, in step S14, the imaging controller 8 calculates a correction coefficient based on the standard luminance value and the extracted luminance value, and multiplies the luminance value of each of the spot areas A1 to A3 by the correction coefficient. A specific method of correcting the luminance values ​​will be described later with reference to Figs. 8 to 10. The process of step S14 is an example of a correction step.

[0047] Next, the imaging controller 8 specifies the radiation dose corresponding to the luminance value of each of the spot areas A1 to A3 based on the correspondence relationship between the luminance value and the radiation dose of the spot areas 1 to 9 stored in the memory (S15). That is, the imaging controller 8 specifies the radiation dose corresponding to the luminance value of each of the spot areas A1 to A3 extracted in step S13 as follows: 211 Each chemical form of At is identified. The process of step S14 is an example of the identifying step.

[0048] Then, the imaging controller 8 may, for example, display on the image display 9 the image captured in step S12 and the radiation dose for each chemical form identified in step S15 in association with each other. 211 Since the radiation dose per unit amount of At is constant, the imaging controller 8 calculates, for example, the radiation dose for each chemical form identified in step S14 as follows: 211 The proportion (amount produced) of each chemical form contained in the At solution may be specified.

[0049] Next, a specific correction method in step S14 will be described with reference to FIGS. 8 to 10, taking the luminance values ​​of spot regions 1 to 9 shown in FIG. 2 as an example. FIG. 8 is a table showing the results of correcting the luminance values ​​of regions 1 to 9 in FIG. 3. FIG. 9 is a graph plotting the luminance values ​​of FIG. 8(A). FIG. 10 is a graph plotting the luminance values ​​of FIG. 8(B). Note that since it is difficult to artificially deteriorate the analysis device 1 over time, deterioration over time is simulated by changing the imaging conditions. That is, a short exposure time corresponds to a large degree of deterioration over time, and a small gain corresponds to a large degree of deterioration over time.

[0050] [Correction method 1] Next, a correction method 1 for the luminance value of a spot area will be described with reference to Fig. 8(A) and Fig. 9. When the correction method 1 is adopted, a linear function formula [exposure time = 0.000013052024 x luminance value - 2.2875065] shown by a dashed line in Fig. 5 is stored in the memory as a predetermined correspondence relationship between a plurality of standard luminance values ​​and exposure times. In addition, the luminance values ​​of spot areas 1 to 9 in Fig. 3 correspond to the luminance values ​​of spot areas A1 to A3 in Fig. 7, the luminance value of area 10 in Fig. 3 corresponds to the extracted luminance value, and the horizontal axis in Fig. 5 corresponds to the standard luminance value.

[0051] First, the imaging controller 8 substitutes the extracted luminance values ​​(=2353018 / 4145921 / 15479454 / 1702110) of the imaging conditions 1 to 4 into the [luminance value] of the formula stored in the memory. Then, the imaging controller 8 sets the exposure time (≒28 / 52 / 200 / 20) obtained by the above formula as the estimated exposure time. Next, the imaging controller 8 multiplies the luminance values ​​of the spot areas 1 to 9 by the reciprocal of the estimated exposure time of the corresponding imaging condition. That is, the correction coefficient in the correction method 1 is the reciprocal of the estimated exposure time.

[0052] The results of the above calculations are shown in Figure 8(A), and when the relationship between the brightness value and radiation dose in Figure 8(A) is plotted, it becomes as shown in Figure 9. As shown in Figure 9, the plots "□", "△", "X", and "●" after correction that correspond to the same radiation dose generally overlap. In other words, by correcting the brightness value of the spot area using the method described above, it is possible to absorb differences in imaging conditions (= the degree of deterioration over time).

[0053] The luminance values ​​shown in Fig. 8(A) correspond to the imaging conditions of exposure time = 1 second and gain = 16 times. Therefore, in step S15 of Fig. 6, the imaging controller 8 uses the correspondence relationship acquired under the imaging conditions described above among the correspondence relationships between luminance values ​​and radiation doses stored in the memory. Alternatively, the imaging controller 8 may further correct the luminance values ​​shown in Fig. 8(A) (for example, if the exposure time when acquiring the correspondence relationship is 20 seconds, each luminance value in Fig. 8(A) is multiplied by 20) in accordance with the imaging conditions when acquiring the correspondence relationship between luminance values ​​and radiation doses stored in the memory.

[0054] [Correction method 2] Next, a correction method 2 for the luminance value of the spot area will be described with reference to Fig. 8(B) and Fig. 10. When the correction method 2 is adopted, a standard luminance value (=15479454) acquired under predetermined imaging conditions (for example, exposure time = 200 seconds, gain = 16 times) is stored in the memory. In addition, the luminance values ​​of the spot areas 1 to 9 in Fig. 3 correspond to the luminance values ​​of the spot areas A1 to A3 in Fig. 7, and the luminance value of the area 10 in Fig. 3 corresponds to the extracted luminance value.

[0055] The imaging controller 8 multiplies the luminance values ​​of the spot regions 1 to 9 by the ratio of the extracted luminance value to the standard luminance value (=extracted luminance value / standard luminance value). That is, the correction coefficient in correction method 2 is extracted luminance value / standard luminance value. The above calculation result is shown in FIG. 8(B), and when the relationship between the luminance value in FIG. 8(B) and the radiation dose is plotted, it becomes as shown in FIG. 10. Correction method 2 can also absorb differences in imaging conditions (=degree of deterioration over time).

[0056] In step S15 of FIG. 6, the imaging controller 8 uses, from among the correspondence relationships between the luminance values ​​and the radiation doses stored in the memory, the correspondence relationship acquired under the same imaging conditions as the standard luminance values.

[0057] According to the above embodiment, for example, the following advantageous effects are achieved.

[0058] According to the above embodiment, the luminance value of the spot region is corrected based on the standard luminance value and the extracted luminance value, thereby reducing the influence of sensitivity deviation caused by deterioration over time of the analysis device 1. As a result, the radiation dose of each chemical form of the radioisotope in the solution can be accurately analyzed over a long period of time.

[0059] Furthermore, by forming the standard optical scintillator 10 from an LYSO crystal, it is possible to emit the same amount of light over a long period of time, and as a result, the analytical precision of the analysis device 1 can be maintained over a long period of time.

[0060] Furthermore, by adopting the method of Fig. 6, thin layer chromatography can be imaged "in situ", and the image obtained can be instantly confirmed as a two-dimensional image using the image display device 9. As a result, the time required for analysis can be optimized. Furthermore, this analysis device 1 and analysis method can be applied not only in the medical field, but also as an analysis method in basic chemistry.

[0061] Although the embodiments of the present invention have been described above, the conditions in the examples are merely examples of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these examples. Various conditions may be adopted in the present invention as long as they do not deviate from the gist of the present invention and achieve the object of the present invention. [Explanation of symbols]

[0062] 1...analysis device, 2...dark box, 3...mounting table, 4...visualization scintillator, 5...objective lens, 6...high-sensitivity camera, 7...camera receiver, 8...imaging controller, 9...image display, 10...standard optical scintillator

Claims

1. 1. A method for analyzing a radioisotope in a solution, comprising the steps of: A separation step of dropping a solution containing a radioisotope onto a thin layer plate and separating the radioisotope into its chemical form by thin layer chromatography; an imaging step of imaging the thin plate through a visualization scintillator that converts radiation into visible light and imaging a standard light scintillator that emits a predetermined amount of standard light; an extraction step of extracting, from the image captured in the imaging step, brightness values ​​of spot regions corresponding to each chemical form of the radioisotope and extracted brightness values ​​of the region of the standard optical scintillator; a correction step of correcting a luminance value of the spot region based on a standard luminance value corresponding to the standard light and the extracted luminance value extracted in the extraction step; and a determination step of determining the radiation dose corresponding to the brightness value of the spot region corrected in the correction step based on a predetermined correspondence relationship between the brightness value of the radioactive isotope and the radiation dose.

2. 2. The method for analyzing a radioisotope according to claim 1, In the correction step, deriving an estimated exposure time corresponding to the extracted luminance value based on a correspondence relationship between a plurality of the standard luminance values ​​and exposure times that has been previously obtained; A method for analyzing a radioisotope, comprising multiplying a luminance value of the spot area by the reciprocal of the estimated exposure time.

3. 2. The method for analyzing a radioisotope according to claim 1, A method for analyzing a radioisotope, wherein in the correction step, the luminance value of the spot region is multiplied by a ratio of the extracted luminance value to the standard luminance value.

4. The method for analyzing a radioisotope according to any one of claims 1 to 3, The standard optical scintillator is Lu 1.9 Y 0.1 SiO 5 1. A method for analyzing a radioisotope, comprising the steps of:

5. The method for analyzing a radioisotope according to any one of claims 1 to 4, You can't do it anymore. 211 Assets, 225 Ac、 223 Ra、 212 Wind、 213 Wind、 149 Tb、 224 Ra、 230 U、 226 Th、 227 Th、 3 H、 7 Path, 11 C、 14 C、 13 N、 18 F、 15 O、 24 Ankle, 28 Mg、 38 Cl、 38 K、 39 Cl、 42 K、 43 K、 43 Scr、 44 Scr、 46 Scr、 47 Scr、 44 You、 48 V、 55 Faith、 56 Co、 57 Co、 58 Co、 57 It、 60 Cu、 61 Cu、 2 Zn、 64 Cu、 67 Cu、 68 Ge、 67 Ga、 68 Ga、 74 As、 76 Br、 81 Kr、 81 Rb、 82 Rb、 83 Rb、 84 Rb、 86 Rb、 86 Y、 87 Y、 90 Y、 89 Sr、 88 Zr、 89 Zr、 95 Zr、 90 Nb、 91 Nb、 92 Nb、 95 Nb、 93 For 99 For 93 Tc 94 Tc 95 Tc 96 Tc 99 Tc 107 Cd 111 in 124 Sb 121 Te 123 I 124 I 125 I 131 I 127 Cs、 132 Cs、 136 Cs、 135 Day, 140 Ba 139 what 141 n.d. 143 PM 148 PM 145 Me、 148 Me、 153 Sm、 161 Tb 166 Ho 167 Yb、 169 Yb、 171 sun 177 sun 171 Hf 172 Hf 173 Hf 175 Hf 169 Ta 177 Ta 178 Ta 179 Ta 177 W、 178 W、 179 W、 181 W、 180 Re 183 Re 184 Re 186 Re 188 Re 188 Pt. 191 Pt. 192 Ir 195 I 196 I 198 I 201 Tl 202 Tl 201 Pb、 203 Pb、 207 Hello 207 And 210 And 213 Fr, 238 Np, 235 U, 255 A method for analyzing a radioactive isotope, comprising either one of the following: Md.

6. An analytical apparatus for analyzing a radioisotope in a solution, comprising: a visualization scintillator that converts radiation into visible light; a standard light scintillator that outputs a predetermined amount of standard light; an imaging device that images, via the visualization scintillator, a thin layer plate in which the radioisotopes have been separated into their respective chemical forms by thin layer chromatography, and also images the standard optical scintillator; a memory for storing a predetermined correspondence relationship between the luminance value of the radioisotope and the radiation dose, and a standard luminance value corresponding to the standard light; a controller for analyzing an image captured by the imaging device; The controller: An extraction step of extracting brightness values ​​of spot areas corresponding to each chemical form of the radioisotope and extracted brightness values ​​of the area of ​​the standard optical scintillator from an image captured by the imaging device; correcting the luminance value of the extracted spot region based on the standard luminance value stored in the memory and the extracted luminance value; An analytical apparatus characterized in that it identifies the radiation dose corresponding to the corrected brightness value of the spot area based on a predetermined correspondence relationship between the brightness value of the radioactive isotope stored in the memory and the radiation dose.

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