Method for extracting technetium 99m from low-specific-activity molybdenum 99, method for producing physiological saline solution containing technetium 99m using said method, and system for recovering technetium 99m from natural molybdenum

Abstract

The present invention extracts technetium 99m from low-specific-activity molybdenum 99 in a short time without being affected by the amount of molybdenum solution.　This method for recovering technetium 99m from low-specific-activity molybdenum 99 comprises separating and recovering daughter nuclide technetium 99m generated by the decay of molybdenum 99 contained in a high-concentration molybdenum solution containing molybdenum 99 having low specific activity by activated carbon, and is characterized in that the activated carbon is immersed in the molybdenum solution, and even if the ratio of the number of atoms of molybdenum 99 is 1016 or more, the trace amount of technetium 99m therein is selectively adsorbed.

Description

Method for extracting technetium-99m from low specific activity molybdenum-99, method for producing physiological saline solution containing technetium-99m using said method, and system for recovering technetium-99m from natural molybdenum

[0001] The present invention is a method for producing radioactive molybdenum-99 ( ９９ Radiopharmaceuticals made from radioactive technetium 99m (Mo) and radioactive technetium 99m (Mo) as a raw material for their labeled compounds ９９ｍ The present invention relates to a process and system for recovering, concentrating, purifying and separating Tc.

[0002] Technetium (Tc) is a transition metal with atomic number 43, located in the 7th group and 5th period. Among the isotopes of Tc, ９９ｍ Technetium 99m (Tc) emits only gamma rays with a short half-life (6 hours) suitable for diagnostic imaging and a low energy (140 keV) suitable for external measurement. ９９ A generator that utilizes radioactive equilibrium with Mo (molybdenum 99) ９９ Mo / ９９ｍ It is generated by a Tc generator and is widely used in nuclear medicine imaging diagnosis. ９９ｍ Tc has a short half-life, so it is usually ９９ Mo (half-life 66 hours) was obtained, ９９ From Mo ９９ｍ It is used in the method for obtaining Tc.

[0003] ９９ Until now, the only method of obtaining Mo has been fissile uranium ( ２３５ It is produced using the nuclear fission method of neutron irradiation of uranium (U), and has a very high specific radioactivity (the strength of radioactivity per unit mass of a substance containing a radioactive isotope). ９９ The fission method, which produces Mo and separates it from the fission products produced at the same time, has been used as a practical technology around the world. ９９ Because Mo has a high specific radioactivity, aluminum oxide (alumina), which is generally used for medical purposes, is used as an adsorbent to adsorb Mo ( ９９ Mo) and adsorbed on an alumina column. ９９ Mo)​９９ Mo daughter nuclides ９９ｍ By eluting (milking) Tc with saline ９９ｍ The method for obtaining Tc is used as a practical manufacturing technique.

[0004] on the other hand, ９９ Uranium is not used as a raw material for obtaining Mo, but rather a molybdenum compound is used as the raw material, and Mo is included as one of its isotopes. ９８ By utilizing the neutron activation (n, γ) reaction of Mo (a neutron capture reaction in which a substance irradiated with neutrons n undergoes a nuclear reaction and emits γ rays when it changes into a radioactive substance), ９９ There is a method to generate Mo, and it is generated by this (n, γ) method. ９９ Compared with the Fission method, Mo ９９ The specific radioactivity of Mo is extremely low, about 1 / 10,000, so the (n, γ) method requires the use of trace amounts of non-radioactive Mo. ９９ A trace amount of daughter nuclide produced from Mo ９９ｍ It is necessary to separate, purify, and recover Tc. The sol-gel method, MEK method, and sublimation method have been investigated and put into practical use as the (n,γ) method. The present inventors have separately developed and proposed the PZC (polyzirconium compound) method, which is a type of sol-gel method as the (n,γ) method.

[0005] Patent Document 1 describes radioactive molybdenum, which is the parent nuclide of technetium. ９９ Mo is produced by irradiating natural isotopes of Mo with neutrons in a nuclear reactor. ９８ It is produced by the Mo(n,γ) reaction, ９９ By passing a Mo solution containing Mo through an activated carbon (AC) column, ９９ It is a daughter nuclide of Mo ９９ｍ The Tc was selectively adsorbed onto AC and collected, and the non-adsorbed Mo( ９９ The sintered body (including Mo) is washed away with water, and then adsorbed onto AC using an alkaline solution (e.g., caustic soda NaOH). ９９ｍ Tc is eluted from the AC, and ９９ｍ Mo contained in the Tc recovery solution, ９９Mo, radioactive impurities, and other impurities are removed by passing the liquid through an AL column packed with aluminum oxide (alumina) placed after the AC column. ９９ｍ A method and apparatus for purifying Tc recovery fluid is described.

[0006] In Patent Document 2, similar to Patent Document 1, a method is described in which natural isotope Mo is used as a raw material and neutrons are irradiated in a nuclear reactor. ９８ Produced by the Mo(n,γ) reaction ９９ Mo to its daughter nuclide ９９ｍ Tc was purified using spherical activated carbon (BAC). ９９ｍ a method for recovering Tc; ９９ The method of passing the Mo solution containing Mo through the AC column by either a pressurized flow, in which the solution is forced into the AC column by a pump, or a reduced pressure flow, in which the solution is sucked in by a pump, was compared. After that, the non-adsorbable Mo ( ９９ After washing away the adsorbed carbon black (including Mo) with water, an alkaline solution (e.g., caustic soda NaOH) was used to remove the adsorbed carbon black. ９９ｍ As a method for eluting Tc from AC, we investigated a method of accelerating elution by heating to about 80°C. ９９ｍ Mo contained in the Tc recovery solution, ９９ Mo, radioactive impurities, and other impurities are removed using a column packed with Al placed after the AC column. ９９ｍ A method and apparatus for purifying Tc recovery fluid is described.

[0007] In Patent Document 3, similar to Patent Documents 1 and 2, a method for producing uranium dioxide by irradiating natural isotopes of Mo as a raw material with neutrons in a nuclear reactor is described. ９８ Produced by the Mo(n,γ) reaction ９９ Mo to its daughter nuclide ９９ｍ The main methods for recovering Tc using AC are: ９９ It was installed inside a double-walled cell to shield radiation such as gamma rays emitted from Mo and prevent leakage of radioactive materials. ９９ The Mo solution tank containing Mo is piped to an external cell equipped with an AC column with low radiation shielding capability, and the Mo solution is piped to the AC column installed in the external cell and then circulated back to the internal Mo solution tank.９９ｍ The structure is such that it selectively adsorbs and collects Tc to prevent radiation leakage to the outside, and then the activated carbon non-adsorbable Mo( ９９ After washing away the adsorbed carbon black (including Mo) with water, an alkaline solution (e.g., caustic soda NaOH) was used to remove the adsorbed carbon black. ９９ｍ Tc is eluted from the AC and finally ９９ｍ Mo contained in the Tc recovery solution, ９９ Mo, radioactive impurities, and other impurities are removed by passing the solution through a column filled with AL placed after the AC column. ９９ｍ A method and apparatus for purifying Tc recovery fluid is described.

[0008] Patent No. 5427483 Patent No. 5916082 Patent No. 6355462

[0009] The prior art described in Patent Documents 1 to 3 is ９９ Generated in a Mo solution containing Mo ９９ｍ To recover Tc, a metal cylindrical container (column) was placed inside, to which the inlet and outlet of the Mo solution were connected. ９９ｍ The column is packed with AC capable of selectively adsorbing Tc, and a Mo solution is passed through the column.

[0010] In the conventional method, the solution is passed through an AC column to extract the molybdenum contained in the Mo solution. ９９ｍ To completely adsorb and capture Tc, Mo( ９９ It is necessary to limit the flow rate when passing the Mo solution through the AC column. Specifically, for low specific activity Mo solution, ９９ Because the Mo concentration is low, the desired amount ９９ｍ To recover Tc, a large amount of Mo ( ９９ Mo) solution must be passed through the AC column. For example, when the flow rate per unit time for passing the solution through an AC column packed with 5 g of AC is 50 to 100 mL / min at maximum, 2.0 L of Mo( ９９ It takes 20 to 40 minutes or more to pass the Mo solution through the membrane, and the membrane has a short half-life. ９９ｍ The task of recovering Tc in a short time and using it for diagnostic purposes lies in work efficiency.

[0011] However, Mo (９９ When the amount of Mo) solution is, for example, 5 to 20 L, ９９ｍ It takes 2 to 5 hours or more to pass the solution through the AC column to adsorb and collect Tc, which reduces the work efficiency and reduces the recovery time of the short half-life of the recovered Tc. ９９ｍ Tc is altered ９９ｇ There is a risk that it will become Tc and become unusable as a pharmaceutical raw material. ９９ｇ Tc (technetium 99 grand) is ９９ｍ It is a radioactive isotope of Tc produced from Tc with a half-life of 211,100 years, and is used as a pharmaceutical raw material. ９９ｍ It is produced in proportion to the time that has passed since the extraction and separation of Tc. If there is too much, it will become a pharmaceutical raw material. ９９ｍ It becomes an impurity of Tc.

[0012] Radioactive molybdenum 99 ( ９９ Mo) into the high concentration Mo solution ９９ It is produced by the decay of Mo and is contained in ９９ Technetium 99m, a daughter nuclide of Mo ( ９９ｍ To recover Tc, Mo( ９９ Mo) atomic ratio is 10 １６ Even if more than this exists, only a small amount of ９９ｍ It is sufficient to use AC that can selectively adsorb and recover Tc.

[0013] Formed in highly concentrated Mo solutions ９９ Mo daughter nuclide ９９ｍ As a method for selectively separating and recovering Tc, a cylindrical metal mesh container containing AC is immersed in a Mo solution, and the surrounding Mo solution is stirred and flowed to separate Tc in the Mo solution. ９９ｍ If the method is to adsorb and collect Tc, there is no need to pass the solution through an AC column, which requires flow rate restriction. ９９ｍ If Tc is adsorbed and collected by AC immersed in a Mo solution, it is not necessary to pass the solution through the AC column for a long time.

[0014] Therefore, an object of the present invention is to provide a method for extracting technetium-99m from low specific activity molybdenum-99 in a short time, without being affected by the amount of molybdenum solution.

[0015] In order to solve the above problems, the method of recovering technetium-99m from low specific activity molybdenum-99 of the present invention is a method of recovering technetium-99m, a daughter nuclide technetium-99m generated by the decay of molybdenum-99 contained in a high-concentration molybdenum solution containing molybdenum-99 with low specific activity, by separating it with activated carbon, and recovering it. The activated carbon is immersed in the molybdenum solution, and the ratio of the number of molybdenum atoms is 10 １６ Even if more than 99m technetium is present, it is characterized by selectively adsorbing a trace amount of technetium-99m.

[0016] In the method for recovering technetium-99m from low specific activity molybdenum-99, the molybdenum solution contains the radionuclide molybdenum-99 produced by the neutron capture (n, γ) reaction of the natural isotope of molybdenum.

[0017] In the method for recovering technetium-99m from low specific activity molybdenum-99, the activated carbon is packed in a metal mesh cylindrical container that is not a column in which the flow rate is restricted, and is immersed in the molybdenum solution that is being stirred and flowing.

[0018] The method of the present invention for producing a physiological saline solution containing technetium-99m comprises washing with water the molybdenum remaining in the pores of activated carbon to which technetium-99m recovered by the method for recovering technetium-99m from low specific activity molybdenum-99 has been adsorbed, passing the solution containing technetium-99m eluted from the activated carbon with an alkaline solution through an IER column packed with a strongly acidic cation exchange resin to remove alkaline components, passing the solution through an AL column packed with alumina to capture the technetium-99m, and eluting the technetium-99m from the alumina column with physiological saline, thereby purifying the solution into a physiological saline solution containing technetium-99m from which impurities have been removed.

[0019] In the method for producing a physiological saline solution containing technetium-99m, the container for accommodating activated carbon, the IER column, and the AL column are made of materials that can be sterilized in an autoclave.

[0020] Furthermore, the system for recovering technetium-99m from natural molybdenum of the present invention comprises: means for producing a highly concentrated molybdenum solution containing molybdenum-99 of low specific activity produced by the neutron capture (n, gamma) reaction of the natural isotope of molybdenum; means for producing a daughter nuclide, technetium-99m, in the molybdenum solution by the decay of molybdenum-99; and means for filling a cylindrical metal mesh vessel, which is not a column with a limited flow rate, with activated carbon and immersing the activated carbon in the molybdenum solution which is being stirred and flowing. The method comprises: a means for washing residual molybdenum-99 from the activated carbon on which technetium-99m has been adsorbed; a means for eluting technetium-99m from the washed activated carbon with an alkaline solution, passing the resulting solution through a strongly acidic cation exchange resin column to remove the alkaline components, and passing the resulting solution through an alumina column to capture technetium-99m; and a means for eluting technetium-99m from the alumina column with physiological saline and recovering purified technetium-99m.

[0021] According to the present invention, radioactive ９９ A high-concentration Mo solution containing Mo is produced and left for about 24 hours. ９９ From Mo ９９ｍ Tc is generated and mixed in radioactive equilibrium (the ratio of the radioactivity of the parent nuclide to the daughter nuclide is constantly balanced), and instead of passing the solution through an AC column as in the past, an AC-filled metal mesh cylindrical container is immersed in a stirred and flowing Mo solution, so that the ９９ｍ Tc can be captured by adsorption onto AC.

[0022] Whether the amount of high-concentration Mo solution is as small as 0.1 L or as large as 5 to 20 L, ９９ From Mo ９９ｍ The elapsed time for Tc to be generated and reach radioactive equilibrium or the desired ９９ｍ At the time when the amount of Tc is generated, the target amount ９９ｍ Since Tc is selectively adsorbed and collected on AC, it is particularly effective for Tc with a short half-life (6 hours). ９９ｍ It is effective in recovering Tc.

[0023] The adsorption and collection of AC in a cylindrical metal mesh container ９９ｍWhen desorbing Tc, the remaining Mo( ９９ Mo) also ９９ｍ It leaches out at the same time as Tc, ９９ｍ By passing the Tc recovery solution through an alumina column, Mo( ９９ It is free from radioactive impurities such as ZnO, and is of high purity suitable for pharmaceutical raw materials. ９９ｍ Tc can be purified and recovered.

[0024]

[0023] Figure 1 is a diagram showing an outline of the method for extracting technetium-99m from low specific activity molybdenum-99 of the present invention, a method for producing a physiological saline solution containing technetium-99m using that method, and a system for recovering technetium-99m from natural molybdenum. Figure 2 is a diagram showing a conventional method for passing a molybdenum solution through an activated carbon column. Figure 3 is a diagram showing the configuration of the method for extracting technetium-99m from low specific activity molybdenum-99 of the present invention, a method for producing a physiological saline solution containing technetium-99m using that method, and a system for recovering technetium-99m from natural molybdenum. Figure 4 is a diagram comparing the process of the method for extracting technetium-99m from low specific activity molybdenum-99 of the present invention with the conventional method. Figure 5 is a diagram showing process conditions for short-time production of the method for producing a physiological saline solution containing technetium-99m of the present invention.

[0025] ９９ Mo solution containing Mo was passed through the AC column. ９９ｍ Instead of recovering Tc, a cylindrical metal (e.g., stainless steel) mesh container filled with AC is placed in the ９９ The AC container is always immersed in the Mo solution tank, and the Mo solution in which the AC container is immersed is stirred and flowed, so that the AC is always ９９ｍ Tc is made adsorbable.

[0026] At a predetermined or arbitrary timing, the AC container is pulled out from the Mo solution, and the non-adsorbed AC remaining in the AC pores is detected. ９９ After removing Mo by washing with water, ９９ｍ AC was captured by treating the AC with Tc adsorbed in an alkaline solution. ９９ｍ Tc is eluted and the solution is purified with a strong acid cation exchange resin (IER) and alumina (AL) to obtain a highly purified ９９ｍ ​Tc is recovered.

[0027] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. ９９ｍ Tc is the radionuclide technetium-99m; ９９ Mo is the radionuclide molybdenum-99. ９９ Mo is the parent nuclide, ９９ｍ Tc is the daughter nuclide. AC is activated carbon, IER is ion exchange resin, and AL is alumina (aluminum oxide).

[0028] 1 and 3 show a method for extracting technetium-99m from low specific activity molybdenum-99, a method for producing a saline solution containing technetium-99m using the method, and a system for recovering technetium-99m from natural molybdenum. ９９ Instead of passing the Mo solution containing Mo through an AC column, the Mo solution was passed through a metal mesh cylindrical container filled with AC. ９９ｍ Tc is adsorbed and collected, ９９ｍ Tc is purified and recovered.

[0029] Figure 2 shows a conventional method for passing a molybdenum solution through an activated carbon column. Figure 4 shows a comparison between the method for extracting technetium-99m from low-specific activity molybdenum-99 of the present invention and the conventional method. Figure 5 shows process conditions for short-time production of a physiological saline solution containing technetium-99m.

[0030] The method for extracting technetium-99m from low specific activity molybdenum-99 involves separating and recovering the daughter nuclide technetium-99m produced by the decay of molybdenum-99 contained in a high-concentration molybdenum solution containing molybdenum-99 with low specific activity using activated carbon.

[0031] The activated carbon is packed in a cylindrical metal mesh container, which is not a column in which the flow rate is restricted, and is immersed in a molybdenum solution that is flowing by stirring, and the ratio of the number of molybdenum atoms is 10 １６ Even if more than 99m of technetium is present, the molybdenum solution selectively adsorbs trace amounts of technetium-99m. The molybdenum solution also contains the radioactive nuclide molybdenum-99, which is produced by the neutron capture (n, γ) reaction of the natural isotope molybdenum.

[0032] The method for producing a physiological saline solution containing technetium-99m involves washing with water the molybdenum remaining in the pores of activated carbon to which technetium-99m recovered by a method for recovering technetium-99m from low specific activity molybdenum-99 has been adsorbed, eluting the solution containing technetium-99m from the activated carbon with an alkaline solution, passing the solution through an IER column packed with a strongly acidic cation exchange resin to remove the alkaline components, passing the solution through an AL column packed with alumina to capture the technetium-99m, and eluting the technetium-99m from the alumina column with physiological saline, thereby purifying the solution into a physiological saline solution containing technetium-99m from which impurities have been removed.

[0033] The system for recovering technetium-99m from natural molybdenum includes: means for producing a highly concentrated molybdenum solution containing molybdenum-99 of low specific activity produced by the neutron capture (n,γ) reaction of the natural isotope of molybdenum; means for producing the daughter nuclide technetium-99m in the molybdenum solution by the decay of molybdenum-99; means for filling a cylindrical metal mesh container that is not a column with a limited flow rate with activated carbon and immersing the activated carbon in a molybdenum solution that is being stirred and flowing; means for washing the remaining molybdenum-99 from the activated carbon on which technetium-99m has been adsorbed; means for eluting the technetium-99m from the washed activated carbon with an alkaline solution, passing the resulting solution through a strong acidic cation exchange resin column to remove the alkaline components, and passing the resulting solution through an alumina column to capture the technetium-99m; and means for eluting the technetium-99m from the alumina column with physiological saline and recovering purified technetium-99m.

[0034] As shown in FIG. 1, a tank 100 storing the Mo solution is ９９ Because Mo has a high radiation dose, it is installed in a radiation-shielded hot cell. The Mo solution tank 100 is equipped with a stirrer 110 for stirring the solution, and also with a support 130 for holding a metal mesh cylindrical container 120 containing AC in the solution. Multiple tanks 100 may be installed in the hot cell.

[0035] Radiopharmaceutical raw materials ９９ｍTo produce Tc, a radionuclide ９９ As a Mo solution containing Mo, Na ２ ９９ MoO ４ The solution is supplied to the tank 100. The natural isotope MoO ３ When neutrons are irradiated to ９９ Mo is produced. ９９ MoO containing Mo ３ When dissolved in an alkaline (NaOH) solution, a neutral pH Na ２ ９９ MoO ４ It becomes a solution.

[0036] radioactive ９９ The Mo solution containing Mo is, for example, 500 g of Mo (MoO ３ It is a high concentration Mo solution containing 750g of Mo. ９９ｍ To obtain Tc, a highly concentrated Mo solution containing 500 g of Mo in 2 L is required, but 50 g of Mo (MoO ３ A high concentration Mo solution containing 75 g of Mo (MoO ３ A high-concentration, large amount of Mo solution containing 7.5 kg of Mo may also be used.

[0037] ９９ A metal mesh cylindrical container 120 containing AC is placed in a tank 100 containing a Mo solution containing Mo, and while it is held in the Mo solution by a support 130, the Mo solution is stirred using a stirrer 110 or the water flow of a circulating pump. ９９ｍ Tc is adsorbed and collected by AC.

[0038] ９９ Generated from Mo ９９ｍ Since Tc reaches a state of radiation equilibrium in about 24 hours, the metal mesh cylindrical container 120 may be pulled out of the Mo solution after waiting for this time to elapse, or may be pulled out at any time before reaching radiation equilibrium. ９９ｍ Tc can be adsorbed by AC. ​​

[0039] As shown in Figure 2, the conventional TcMM (Technetium 99m Master Milker) ９９ｍ In this method, the entire amount of Mo solution is passed through an AC column to adsorb Tc onto AC. The AC column is a cylindrical container filled with AC, and the liquid comes into contact with the AC as it passes through the cylinder from the inlet to the outlet. In this method, the flow rate of the Mo solution passing through the AC column is limited, which limits the AC column's ability to process the Mo solution, resulting in a short half-life (lifespan). ９９ｍ There are problems with the technology for recovering Tc.

[0040] As shown in Figure 3, from the low specific activity Mo solution ９９ｍ The system for highly concentrating, purifying and recovering Tc is installed in a hot cell 140 isolated by a thick shielding wall to shield it from high radiation. ９９ MoO ３ Dissolve in alkali ９９ MoO ３ The solution is prepared in advance in a plurality of storage tanks 100 each having a capacity of 1 to 20 L provided in the hot cell 140. ９９ MoO ３ Supply the solution, ９９ A highly concentrated Mo solution with a Mo radioactivity of 500 Ci is stored.

[0041] The metal mesh cylindrical container 120 containing the AC is placed in the tank 100 using a hook, a carrier, etc., and is supported by a support 130. ９９ It is kept in a Mo solution containing Mo. ９９ The collapse of Mo ９９ｍ It changes to Tc, ９９ｍ The result is a Mo solution containing Tc.

[0042] After the metal mesh cylindrical container 120 is immersed in the Mo solution, the Mo solution is stirred with the stirrer 110 so that the Mo solution can be efficiently brought into contact with the AC. ９９ｍ The metal mesh cylindrical container 120 is lifted out of the tank 100. ９９ｍ The AC with adsorbed Tc is collected. Then, the AC is placed in a column and washed with water to remove the remaining non-adsorbed Tc. ９９Mo and the like are removed by washing.

[0043] An alkaline (NaOH) solution is supplied to the AC-containing column while adjusting the flow rate and temperature. By treating with the alkaline solution, the AC is converted into the alkaline solution. ９９ｍ Tc was eluted and excreted ９９ｍ The alkaline solution containing Tc is passed through the IER column 150. The alkaline component is captured by the strongly acidic cation exchange resin in the IER column 150 and discharged. ９９ｍ A solution containing Tc is passed through the AL column 160 .

[0044] Alumina with AL column 160 ９９ｍ Then, by passing physiological saline with a NaCl concentration of about 0.9% through the AL column 160, Tc is captured and the impurities are discharged. ９９ｍ Tc elutes. ９９ｍ TcO ４ It becomes a solution and is excreted with saline, so it is highly purified and ９９ｍ By recovering it as a physiological saline solution containing Tc, it can be used as a raw material for radiopharmaceuticals and labeled compounds.

[0045] High purity from high concentration Mo solution ９９ｍ The waste and waste liquid generated in the process of purifying and recovering Tc can be solidified after the radioactivity attached to them has naturally decayed to a low level. A space for storing and accommodating various radioactive and non-radioactive wastes generated in the process may be provided in the hot cell 140 or the like.

[0046] The container for storing the AC (metal mesh cylindrical container 120, AC storage column for washing the AC with water), the IER column 150, and the AL column 160 are preferably made of materials and have contents (AC, IER, AL) that can be sterilized in an autoclave (121°C, 2 atmospheres).

[0047] As shown in Figure 4, the conventional method and the process of the present invention are compared. In the conventional method, the solution is passed through an AC column to extract the molybdenum contained in the Mo solution. ９９ｍThis is a flow-type TcMM that adsorbs and collects Tc. Instead of passing a Mo solution through an AC column, the present invention immerses a cylindrical metal mesh container 120 containing an AC in a flowing high-concentration Mo solution, thereby adsorbing and collecting Tc. ９９ｍ This is an improved batch-type TcMM in which Tc is adsorbed onto AC.

[0048] In the conventional method, the Mo solution is passed through an AC column to extract the Mo contained in the Mo solution. ９９ｍ To completely adsorb and collect Tc, it was necessary to provide a flow rate restriction in the AC column to allow the Mo solution to flow. Specifically, for low specific activity Mo solution, ９９ Because the concentration of Mo is low, the desired amount ９９ｍ To recover Tc, it is necessary to pass a large amount of Mo solution through the AC column. For example, if the flow rate per unit time for passing the solution through the AC column is set to a maximum of 50 to 100 mL / min, it takes 20 to 40 minutes or more to pass 2.0 L of Mo solution through the AC column, which has a short half-life. ９９ｍ The work efficiency is not good for recovering Tc in a short time and using it for diagnosis.

[0049] Moreover, in the case of a low-concentration Mo solution, ９９ｍ To become Tc, ９９ｍ When Tc is adsorbed and collected on an AC column, a larger amount of Mo solution is passed through the AC column. For example, when the amount of Mo solution is 5 to 20 L, it takes 2 to 5 hours or more to pass the solution through the AC column, and the collected ９９ｍ Tc is altered ９９ｇ Tc, which may render it unusable as a pharmaceutical ingredient.

[0050] On the other hand, in the present invention, the AC contained in the metal mesh cylindrical container 120 is ９９ In a high concentration Mo solution containing Mo ９９ It is a daughter nuclide produced by the decay of Mo. ９９ｍ For Tc ９９ The ratio of the number of Mo atoms is 10 １６ Even if there are more than ９９ｍ Tc can be selectively separated and recovered.

[0051] The metal mesh cylindrical container 120 containing the AC is immersed in the Mo solution, and the Mo solution is stirred to flow around the metal mesh cylindrical container 120. ９９ｍ It is not necessary to adjust the flow rate of the Mo solution to pass it through the AC column, and the Tc is always absorbed from the entire Mo solution present around the metal mesh cylindrical container 120. ９９ｍ Tc is adsorbed by AC, so it ９９ｍ This makes it possible to collect Tc.

[0052] As shown in FIG. 5, a cylindrical metal mesh container 120 containing AC was immersed in the Mo solution. ９９ｍ Tc was adsorbed and collected from AC and purified as a pharmaceutical raw material. ９９ｍ The time required for each step to recover Tc is significantly reduced compared to the conventional method. ９９ Regardless of the radioactivity of Mo, AC is always ９９ｍ Since Tc is adsorbed and collected, the process time required for this is zero. ９９ｍ The time required to purify and recover Tc is approximately 10 minutes, and the process can be performed consistently over a fixed period of time, making this an ideal method for manufacturing pharmaceutical raw materials that require strict quality and shipping arrangements.

[0053] MoO containing a very large amount of Mo (2,500 g) ３ (3,750 g) was dissolved in 6 M (molar concentration mol / L) NaOH (1.75-1.8 L), and then ２ O was added to prepare a Mo solution (10 L) with a pH of 8 to 9. The Mo solution was placed in a 15 L beaker and ９９ｍ0.1 mg of Re (rhenium) was added as a substitute for Tc (500 Ci). A stainless steel cylindrical metal mesh container (1.6 cm diameter, 6 cm length, 12 cc capacity) filled with AC (4.5 g) was immersed in the Mo solution, and the stirring blade was rotated (30 rpm) in the Mo solution for 6 hours. After stirring, the metal mesh cylindrical container was removed from the Mo container and washed with water to remove any Mo remaining unadsorbed in the AC pores. Re adsorbed on AC was then eluted with 1.3 M NaOH (30 mL). The solution was passed through an IER column packed with a strongly acidic cation exchange resin, and then through an AL column containing activated alumina (6 g), where Re was adsorbed and captured by the alumina. 20 mL of physiological saline (0.9% NaCl) was passed through the AL column to which Re had been adsorbed, and a physiological saline solution (pH 4.8 to 5.2) containing Re was collected.

[0054] In addition, ９９ The half-life of Mo is 65.94 hours. ９９ｍ The half-life of Tc is 6.01 hours. ９９ The amount of Mo (500 Ci) was 1.04 mg, which is 1 / 500,000 of Mo (500 g). ９９ｍ The amount of Tc (500 Ci) was 0.095 mg, which was 5 million times less than Mo (500 g). At the μCi test level, ９９ The radioactivity of Mo is 5 x 10 ４ The weight ratio to Mo (500g) is 6e －１５ is less than ９９ｍ The radioactivity of Tc is 6 x 10 ４ The weight ratio to Mo (500g) is 6e －１６ As a result of a radioactivity test in a wide range from μCi level to 80 Ci level and a non-radioactivity test equivalent to 500 Ci (Mo 500 g or more) TcMM test, the separation factor of Mo and Tc by AC (selective adsorption of Tc) was 10 e １６ That was all.

[0055] The amount of Re recovered was 0.092 to 0.096 mg, and the recovery rate of Re was approximately 94%. ９９ｍSince the Re is equivalent to Tc (500 Ci), a metal mesh cylindrical container filled with AC was immersed in a Mo solution. ９９ｍ It is thought that similar results will be obtained when Tc is adsorbed and collected by AC. ９９ Daughter nuclides produced by the decay of Mo ９９ｍ For Tc ９９ The ratio of the number of Mo atoms is 10 １６ Even if there are more than ９９ｍ This indicates that AC selectively adsorbs Tc.

[0056] According to the present invention, radioactive ９９ A high-concentration Mo solution containing Mo is produced and left for about 24 hours. ９９ From Mo ９９ｍ Tc is generated and mixed in radioactive equilibrium (the ratio of the radioactivity of the parent nuclide to the daughter nuclide is constantly balanced), and instead of passing the solution through an AC column as in the past, an AC-filled metal mesh cylindrical container is immersed in a stirred and flowing Mo solution, so that the ９９ｍ Tc can be captured by adsorption onto AC.

[0057] Whether the amount of high-concentration Mo solution is as small as 0.1 L or as large as 5 to 20 L, ９９ From Mo ９９ｍ The elapsed time for Tc to be generated and reach radioactive equilibrium or the desired ９９ｍ At the time when the amount of Tc is generated, the target amount ９９ｍ Since Tc is selectively adsorbed and collected on AC, it is particularly effective for Tc with a short half-life (6 hours). ９９ｍ It is effective in recovering Tc.

[0058] The adsorption and collection of AC in a cylindrical metal mesh container ９９ｍ When desorbing Tc, the remaining Mo( ９９ Mo) also ９９ｍ It leaches out at the same time as Tc, ９９ｍ By passing the Tc recovery solution through an alumina column, Mo( ９９ It is free from radioactive impurities such as ZnO, and is of high purity suitable for pharmaceutical raw materials. ９９ｍ Tc can be purified and recovered.

[0059] Although the embodiments of the present invention have been described above, the present invention is not limited to these.

[0060] 100: Mo solution tank 110: Stirrer 120: Metal mesh cylindrical container 130: Support 140: Hot cell 150: IER column 160: AL column

Claims

1. A method for recovering technetium-99m from low-specific activity molybdenum-99 by separating with activated carbon the daughter nuclide technetium-99m produced by the decay of molybdenum-99 contained in a high-concentration molybdenum solution containing molybdenum-99 of low specific activity, characterized in that the activated carbon is packed in a cylindrical metal mesh container that is not a column with a restricted flow rate, and is immersed in the molybdenum solution that is being stirred to flow, thereby selectively adsorbing trace amounts of technetium-99m in the solution.

2. The method for recovering technetium-99m from low specific activity molybdenum-99 according to claim 1, characterized in that the molybdenum solution contains the radioactive nuclide molybdenum-99 produced by the neutron capture (n, γ) reaction of the natural isotope of molybdenum.

3. A method for producing a physiological saline solution containing technetium-99m, comprising: washing with water the molybdenum remaining in the pores of activated carbon to which technetium-99m recovered by the method for recovering technetium-99m from low specific activity molybdenum-99 as set forth in claim 1 or 2 has been adsorbed; passing the solution containing technetium-99m eluted from the activated carbon with an alkaline solution through an IER column packed with a strongly acidic cation exchange resin to remove the alkaline components; passing the solution through an AL column packed with alumina to capture the technetium-99m; and eluting the technetium-99m from the alumina column using physiological saline, thereby purifying the solution into a physiological saline solution containing technetium-99m from which impurities have been removed.

4. The method for producing a physiological saline solution containing technetium-99m according to claim 3, characterized in that the container for accommodating the activated carbon, the IER column, and the AL column are made of materials that can be sterilized in an autoclave.

5. A method for producing a high-concentration molybdenum solution containing molybdenum-99 of low specific activity produced by the neutron capture (n, gamma) reaction of the natural isotope molybdenum; a means for producing a daughter nuclide, technetium-99m, in the molybdenum solution by the decay of molybdenum-99; a means for filling a cylindrical metal mesh vessel, which is not a column with a restricted flow rate, with activated carbon and immersing the activated carbon in the molybdenum solution that is being stirred and flowing; a means for washing the remaining molybdenum-99 from the activated carbon with which technetium-99m has been adsorbed; a means for eluting the technetium-99m from the washed activated carbon with an alkaline solution, passing the solution through a strong acid cation exchange resin column to remove the alkaline components, and passing the resulting solution through an alumina column to capture the technetium-99m; and a means for eluting the technetium-99m from the alumina column with physiological saline and recovering purified technetium-99m. A system for recovering technetium-99m from natural molybdenum.

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