Method for extracting technetium 99m from molybdenum 99 of low specific activity, method for producing physiological saline water containing technetium 99m using the method, and system for recovering technetium 99m from natural molybdenum

Abstract

To extract technetium 99m from low specific activity Mo 99 in a short time, without being influenced by an amount of a molybdenum solution.SOLUTION: A method for recovering technetium-99m from low specific radioactivity molybdenum-99 involves separating and collecting the daughter nuclide technetium-99m, which is produced by the decay of molybdenum-99 contained in a high-concentration molybdenum solution with low specific activity, using activated carbon. The activated carbon is characterized by being immersed in the molybdenum solution and selectively adsorbing trace amounts of technetium-99m present, even when the molybdenum-99 to atom ratio is 1016 or higher.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention is a low specific activity 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 This paper relates to the recovery, concentration, purification and separation process and system of Tc. [Background technology]

[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) has a short half-life (6 hours) suitable for diagnostic imaging and emits only gamma rays with a low energy (140 keV) suitable for external measurement. 99 A generator using radioactive equilibrium with Mo (molybdenum 99) 99 Mo / 99m It is generated by a Tc generator and is widely used in nuclear medicine imaging diagnostics. 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 way to obtain Mo has been through fission uranium ( 235 It is produced using the nuclear fission method by neutron irradiation of uranium (U; uranium), and has a very high specific radioactivity (strength of radioactivity per unit mass of a material 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 commonly used for medical purposes, is used as an adsorbent to measure Mo( 99 Mo) was supported on an alumina column, and Mo( 99 Mo) 99Mo daughter nuclides 99m By eluting (milking) Tc with saline 99m The method for obtaining Tc is actually used as a 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 material irradiated with neutrons n undergoes a nuclear reaction and emits gamma rays when it is transformed into a radioactive material), 99 There is a method to generate Mo, and it is generated by this (n,γ) method. 99 Compared to the Fission method, Mo 99 The specific radioactivity of Mo is extremely low, about 1 / 10,000, so the (n,γ) method requires the detection of trace amounts of non-radioactive Mo in large amounts. 99 Trace amounts of daughter nuclides produced from Mo 99m It is necessary to separate, purify, and recover Tc. To date, 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, 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 in a nuclear reactor. 98 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 Mo) is washed away with water, and then an alkaline solution (such as caustic soda NaOH) is used to adsorb it onto AC. 99m Tc is eluted from AC and then 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, natural isotope Mo is used as a raw material and neutron irradiation is performed in a nuclear reactor. 98 Produced by the Mo(n,γ) reaction 99 Mo to its daughter nuclide 99m Tc was detected using spherical activated charcoal (BAC). 99m How to recover Tc, 99 We compared and examined the methods of passing the Mo solution 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. After that, we investigated the non-adsorbed Mo( 99 After washing away the ions (including Mo) with water, the ions were adsorbed onto AC using an alkaline solution (e.g., caustic soda NaOH). 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 by 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, natural isotope Mo is used as a raw material and neutron irradiation is performed in a nuclear reactor. 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. 99The Mo solution tank containing Mo is piped to an external cell equipped with an AC column with low radiation shielding capacity, and the Mo solution is then 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 Tc is selectively adsorbed and collected to prevent radiation leakage to the outside, and then the activated carbon non-adsorbed Mo( 99 After washing away the ions (including Mo) with water, the ions were adsorbed onto AC using an alkaline solution (e.g., caustic soda NaOH). 99m Tc is eluted from 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 packed with Al placed after the AC column. 99m A method and apparatus for purifying Tc recovery fluid is described. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5427483 [Patent Document 2] Patent No. 5916082 [Patent Document 3] Patent No. 6355462 Summary of the Invention [Problem to be solved by the invention]

[0009] The prior art described in Patent Documents 1 to 3 is 99 Generated in a Mo solution containing Mo 99m To collect Tc, a metal cylindrical container (column) was placed inside, with the inlet and outlet of the Mo solution 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 and the Mo solution is 99mTo completely adsorb and capture Tc, Mo( 99 It is necessary to limit the flow rate when passing the Mo solution through a flow-through 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 5 g of AC through an AC column is 50-100 mL / min, 2.0 L of Mo( 99 It takes 20 to 40 minutes or more to pass the Mo solution through the reactor, and the reaction has a short half-life. 99m The challenge in recovering Tc in a short time and using it for diagnostic purposes is 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 collected Tc. 99m Tc is altered 99g There is a risk that it will become Tc and become unusable as a pharmaceutical ingredient. 99g Tc (technetium 99grand) 99m It is a radioactive isotope of Tc that is produced from Tc and has 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 in 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, which can selectively adsorb and recover Tc.

[0013] Formed in highly concentrated Mo solutions 99 Mo daughter nuclides 99m As a method for selectively separating and recovering Tc, a cylindrical metal mesh container containing AC was immersed in a Mo solution, and the surrounding Mo solution was stirred and flowed to separate and recover Tc. 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 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. [Means for solving the problem]

[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 generated by the decay of molybdenum-99 contained in a high-concentration molybdenum solution containing molybdenum-99 with low specific activity, by separating and recovering the technetium-99m using activated carbon, the daughter nuclide being generated by the decay of molybdenum-99. The activated carbon is immersed in the molybdenum solution, and the ratio of the number of molybdenum atoms is 10 16 It is characterized by its ability to selectively adsorb even trace amounts of technetium 99m, even if more than this amount is present.

[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 cylindrical metal mesh 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 present invention also provides a method for producing a physiological saline solution containing technetium-99m, which 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 described above has been adsorbed; eluting the technetium-99m-containing solution 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; further 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 containing the 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,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; 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 the remaining molybdenum-99 from the activated carbon on which technetium-99m has been adsorbed; a means for eluting the 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 the technetium-99m; and a means for eluting the technetium-99m from the alumina column with physiological saline and recovering the purified technetium-99m. [Effects of the Invention]

[0021] According to the present invention, radioactive 99 By creating a high-concentration Mo solution containing Mo and leaving it 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, allowing the 99m Tc can be adsorbed onto AC and captured.

[0022] Whether the amount of high concentration Mo solution is as small as 0.1L or as large as 5-20L, 99 From Mo 99m The time elapsed since Tc was generated and reached radioactive equilibrium, or the desired time 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] Adsorbed and collected on AC in a cylindrical metal mesh container 99m When Tc is desorbed, the remaining Mo( 99 Mo) 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 Mo, and is of high purity suitable for pharmaceutical raw materials. 99m Tc can be purified and recovered. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a diagram showing an outline of the method for extracting technetium-99m from low specific activity molybdenum-99 according to the present invention, a method for producing a physiological saline solution containing technetium-99m using the method, and a system for recovering technetium-99m from natural molybdenum. [Figure 2] FIG. 1 is a diagram showing a conventional method for passing a molybdenum solution through an activated carbon column. [Figure 3] FIG. 1 is a diagram showing the configuration of a method for extracting technetium-99m from low-specific activity molybdenum-99 according to the present invention, a method for producing a physiological saline solution containing technetium-99m using the method, and a system for recovering technetium-99m from natural molybdenum. [Figure 4] FIG. 1 is a diagram comparing the process of the present invention for extracting technetium-99m from low specific activity molybdenum-99 with the process of a conventional method. [Figure 5] FIG. 1 is a diagram showing the process conditions for short-time production of a physiological saline solution containing technetium-99m according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] 99 Mo solution containing Mo was passed through the AC column. 99m Instead of collecting 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 it is immersed is stirred and flowed, so that the AC is always 99m Make Tc available for adsorption.

[0026] At a predetermined or arbitrary timing, the AC container is removed from the Mo solution, and the non-adsorbed AC remaining in the AC pores is analyzed. 99 After removing Mo by washing with water, 99m AC was captured by treating 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 Tc. 99m Recover Tc.

[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, 99mTc is the daughter nuclide. AC is activated carbon, IER is ion exchange resin, and AL is alumina (aluminum oxide).

[0028] Figures 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 that 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 measured in an AC-filled cylindrical metal mesh container. 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 compares the process of the present invention for extracting technetium-99m from low-specific activity molybdenum-99 with that of 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 where the flow rate is restricted, and is immersed in a molybdenum solution that is flowing by stirring. 16 Even if more than 99m of technetium is present, it selectively adsorbs the trace amount of technetium 99m. The molybdenum solution also contains the radioactive nuclide molybdenum 99, which is produced by the neutron capture (n, gamma) 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 in 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, and then passing the solution through an AL column packed with alumina to capture the technetium-99m. Technetium-99m is then eluted 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.

[0033] The system for recovering technetium-99m from natural molybdenum comprises: a 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; a means for producing the daughter nuclide technetium-99m in the molybdenum solution by the decay of molybdenum-99; a means for filling a cylindrical metal mesh vessel (not a column with a restricted flow rate) with activated carbon and immersing the activated carbon in a stirred molybdenum solution; a means for washing the remaining molybdenum-99 from the activated carbon with technetium-99m; a 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 a means for eluting the technetium-99m from the alumina column with physiological saline to recover purified technetium-99m. [Example]

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

[0035] Radiopharmaceutical raw materials 99m To produce Tc, a radionuclide 99 As a Mo solution containing Mo, Na2 99 MoO4 solution is supplied to the tank 100. When natural isotope MoO3 is irradiated with neutrons in a nuclear reactor in advance, 99 Mo is produced. 99 When MoO3 containing Mo is dissolved in an alkaline (NaOH) solution, a neutral pH Na2 99 This results in a MoO4 solution.

[0036] radioactive 99 The Mo solution containing Mo is a high-concentration Mo solution containing, for example, 500 g of Mo (750 g as MoO3) in 2 L. 99m To obtain Tc, a high-concentration Mo solution containing 500 g of Mo in 2 L is required, but a high-concentration Mo solution containing 50 g of Mo (75 g as MoO3) in 200 mL, one-tenth of that amount, or a large amount of high-concentration Mo solution containing 5 kg of Mo (7.5 kg as MoO3) in 20 L, ten times the amount, can 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 circulation 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 This method involves passing the entire amount of Mo solution through an AC column in order 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 enriching, purifying and recovering Tc is installed in a hot cell 140 isolated by thick shielding walls to shield against high radiation. 99 Dissolve MoO3 in alkali 99 A MoO3 solution is prepared in advance. A plurality of storage tanks 100 with a capacity of 1 to 20 L are provided in the hot cell 140. 99 MoO3 solution is supplied. 99 A high-concentration 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 This results in a Mo solution containing Tc.

[0042] Once the metal mesh cylindrical container 120 is immersed in the Mo solution, it is advisable to stir the Mo solution 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 any remaining non-adsorbed Tc. 99 Mo and other substances 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 An alkaline solution containing Tc is passed through the IER column 150. In the IER column 150, the alkaline components are captured by the strongly acidic cation exchange resin and discharged. 99m The solution containing Tc is passed through the AL column 160 .

[0044] Alumina with AL column 160 99m Tc is captured and impurities are discharged. Then, by passing saline solution with a NaCl concentration of about 0.9% through the AL column 160, the alumina converts the solution into saline solution. 99m Tc is eluted. 99m It becomes a TcO4 solution and is excreted with saline, so it is purified to a high degree. 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 refining and recovering Tc can be solidified after the radioactivity attached to them has naturally decayed to a low level. A space for storing various radioactive and non-radioactive waste 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 rinsing the AC with water), IER column 150, and 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 Mo contained in the 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 detecting the Tc generated in the Mo solution. 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 detect the Mo contained in the solution. 99m To completely adsorb and capture Tc, it was necessary to set a flow restriction in the AC column to allow the Mo solution to flow. Specifically, for low specific activity Mo solution, 99 The concentration of Mo is low, so the desired amount 99m To recover Tc, a large amount of Mo solution must be passed 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 50-100 mL / min, it takes 20-40 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 diagnostic purposes.

[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, if 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 Tc is 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 The 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 metallic mesh cylindrical container 120 containing the AC was immersed in the Mo solution, and the Mo solution was stirred to flow around the metallic 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 entire Mo solution present around the metal mesh cylindrical container 120 is always absorbed. 99m Tc is adsorbed by AC, so it 99m It becomes 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 shorter than that of 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. [Example]

[0053] MoO3 (3,750 g) containing a very large amount of Mo (2,500 g) was dissolved in 6 M (molarity mol / L) NaOH (1.75-1.8 L), and then H2O was added to prepare a Mo solution (10 L) with a pH of 8-9. The Mo solution was placed in a 15 L beaker and 99mA 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 0.1 mg of Re (rhenium) was added as a substitute for Tc (500 Ci). The container was stirred for 6 hours at 30 rpm. After stirring, the metal mesh cylindrical container was removed from the Mo container and washed with water to remove any unadsorbed Mo remaining in the AC pores. The adsorbed Re was then eluted with 1.3 M NaOH (30 mL). The solution was passed through an IER column packed with a strong acid cation exchange resin and then through an AL column containing activated alumina (6 g), where the Re was adsorbed and captured on the alumina. 20 mL of saline (0.9% NaCl) was passed through the AL column, and a saline solution (pH 4.8–5.2) 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) is 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 that of Mo (500 g). At the μCi test level, 99 The radioactivity of Mo is 5×10 4 Less than Bq (Becquerel), the weight ratio to Mo (500g) is 6e -15 is less than 99m The radioactivity of Tc is 6 × 10 4 Less than Bq (Becquerel), the weight ratio to Mo (500g) is 6e -16 The results of a radioactivity test covering a wide range from μCi to 80Ci and a non-radioactivity test equivalent to 500Ci (Mo 500g or more) with TcMM showed that the separation factor (selective adsorption of Tc) between Mo and Tc by AC was 10e 16 That was all.

[0055] The amount of recovered Re was 0.092 to 0.096 mg, and the recovery rate of Re was approximately 94%. 99mSince the amount of Re is equivalent to Tc (500 Ci), a cylindrical metal mesh container filled with AC was immersed in a Mo solution. 99m It is thought that similar results would 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 By creating a high-concentration Mo solution containing Mo and leaving it 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, allowing the 99m Tc can be adsorbed onto AC and captured.

[0057] Whether the amount of high concentration Mo solution is as small as 0.1L or as large as 5-20L, 99 From Mo 99m The time elapsed since Tc was generated and reached radioactive equilibrium, or the desired time 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] Adsorbed and collected on AC in a cylindrical metal mesh container 99m When Tc is desorbed, the remaining Mo( 99 Mo) 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 Mo, and is of high purity suitable for pharmaceutical raw materials. 99mTc 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. [Explanation of symbols]

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

Claims

1. A method for recovering technetium-99m, a daughter nuclide produced by decay of molybdenum-99 contained in a highly concentrated molybdenum solution containing molybdenum-99 with low specific activity, by separating it with activated carbon, comprising: 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 of technetium is present, it selectively adsorbs trace amounts of technetium-99m. A method for recovering technetium-99m from low specific activity molybdenum-99.

2. The molybdenum solution contains the radionuclide molybdenum-99 produced by the neutron capture (n, γ) reaction of the natural isotope of molybdenum.

2. The method for recovering technetium-99m from low specific activity molybdenum-99 according to claim 1.

3. The activated carbon is packed in a cylindrical metal mesh container that is not a column in which flow is restricted, and is immersed in the molybdenum solution that is being stirred and kept flowing.

2. The method for recovering technetium-99m from low specific activity molybdenum-99 according to claim 1.

4. 4. The method for recovering technetium-99m from low specific activity molybdenum-99 according to claim 1, further comprising the step of washing with water the molybdenum remaining in the pores of the activated carbon to which the technetium-99m has been adsorbed; The solution containing technetium-99m eluted from the activated carbon with an alkaline solution is passed through an IER column packed with a strongly acidic cation exchange resin to remove the alkaline components. The solution is then passed through an AL column packed with alumina to capture technetium-99m. Technetium-99m is eluted from the alumina column using physiological saline, thereby purifying the technetium-99m into a physiological saline solution containing impurities removed. A method for producing a physiological saline solution containing technetium-99m, comprising:

5. The container for accommodating the activated carbon, the IER column, and the AL column are made of materials that can be sterilized by autoclave.

5. The method for producing a physiological saline solution containing technetium-99m according to claim 4.

6. a 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 generating a daughter nuclide, technetium-99m, in the molybdenum solution by decay of molybdenum-99; a means for filling activated carbon in a cylindrical metal mesh vessel, which is not a column in which the flow rate is restricted, and immersing the activated carbon in the molybdenum solution which is being stirred and flowing; a means for washing the remaining molybdenum-99 from the activated carbon on which the technetium-99m has been adsorbed; a means for eluting technetium-99m from the water-washed activated carbon with an alkaline solution, passing the eluate through a strongly acidic cation exchange resin column to remove the alkaline components, and then passing the resulting solution through an alumina column to capture technetium-99m; and a means for eluting the technetium-99m from the alumina column with saline and recovering the purified technetium-99m. A system for recovering technetium-99m from natural molybdenum.

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