The method of extraction of receipt of technetium-99m and a device for its implementation

 

(57) Abstract:

The invention can be used to produce radiopharmaceuticals for medicine. The method is carried out by repeated extraction with the same small volume of extractant for one act of excretion of the radionuclide due to the introduction along with the extraction column additional columns with the ability to message each other and providing opportunities for alternately carrying out the extraction. Exercise dynamic control over the location of the boundary between aqueous and organic phases by introducing additional quantities or transfer of the excess of the aqueous phase of the additional columns in the extraction at the time of selection of the extractant. The invention will improve the efficiency of the extraction, reduces the size of the machine, ensures trouble-free operation. 2 S. and 1 C.p. f-crystals, 1 Il.

The invention relates to the field of applied radiochemistry, in particular the production of radiopharmaceuticals for medicine.

Technetium-99M is produced by nuclear reactions

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for example, when irradiated salts of molybdenum neutron nuclear reactor, it is a daughter product of the decay machine for the diagnosis of various diseases, in the study of the cardiovascular system, thyroid, malignant tumors, etc.

The above reaction (1) describes the generator system, which is the accumulation time of the isotope99MTc. For isolation and separation from the parent radionuclide99Mo can be used a variety of methods: adsorption, chromatography and extraction. On the basis of the first two methods developed small portable generators are designed for concurrent maintenance 1 - 2 medical institutions.

In contrast, the extraction generators are stationary, can satisfy the need for short-lived isotopes of large regions of the country.

The main challenge when using solvent extraction technology is to increase the yield of technetium from the installation, provided remote control of the process, because the overall activity level of the feedstock, usually more than 10 - 20 CI.

Increased output can be achieved even when using the same extractant) by increasing the efficiency of extraction, but also due to the more complete the Department shall, for example, by intensive mixing of aqueous and organic phases before their subsequent separation. An example of such a method of extraction of receipt of technetium-99M and extraction generator technetium-99M can be the way and the generator, the concept of which is given in the book Sokolov, C. A. Generators Korotkova radioactive isotopes. M: Atomizdat, 1975, S. 12,13, 29. The installation consists of the extractor with a stirrer, which served the original alkaline solution with the parent isotope99Mo and extractant, such as methyl ethyl ketone, to highlight the daughter isotope99MTc. After stirring the mixture and separation of the organic phase containing the isotope99MTC her through a tube, one end of which is located on the border of aqueous and organic phases, is pumped into the evaporator. Hence, the solvent is distilled off, and the dry residue containing the technetium-99M, dissolve in isotonic NaCl (0.9 per cent). The resulting solution was selected for further use.

The main disadvantage of the above described generator is the inability of the selection of the extract without the implementation of its losses, because in this case the surface of the separation of phases is large, and when the offset end of the intake tube of neposredno the IMO. The generator is not designed for operation in remote mode.

The technical problem is solved by the fact that the loading substance dissolution with the parent radionuclide 99Mo and extraction of technetium-99 is carried out in an extraction column.

In contrast to the known method, the extraction is carried out iteratively by alternately feed content extraction columns in the additional column and back, which in turn create a negative pressure in both columns, the selection of the extractant with technetium after the extraction is carried out additional columns through intake tube, creating a vacuum in the filter column-vaporizer-a collection of extractant.

In contrast to the known device, comprising a loading unit, an extraction column with the scattering ring in the middle part and the porous wall at the bottom, under which in the case of the column-mounted in the pipe, and a nozzle in the upper part of the column to join the air-vacuum system, a column with sorbent with a porous septum in the lower part of the evaporator, the capacity for pertechnitat sodium, site selection pertechnitat with bottle-collector and the auxiliary tank with the middle part of the narrowing of the printed label on it to control the level of the aqueous phase, when this column with the lower pipe is connected through one-way valve with bottom outlet added columns are also connected to the air-vacuum system and having the same construction and extraction column, but in its top mounted intake tube, one end of which is located in the center of its narrower part, and the other opened into the column with sorbent and has at one end a conical spray. The upper portion of the column tightly welded.

In the proposed method and device allows multiple extraction of technetium in the same small volume of extractant by rotating the delivery of content extraction columns after the initial extraction in the additional column and back. When this layer of the extractant, while above the water phase after primary extraction, re-pass through the layer of the aqueous phase during its transfer through the lower nozzle extraction columns in an additional column. The extraction process is repeated again when translating an additional column through the lower pipe in the extraction column, and so on

Trouble-free operation the gene is in an additional column, where is the intake tube, an evaporator connected with the atmospheric air through the filter column goes in the intake tube, thereby displacing and preventing the penetration of the aqueous phase on the filter.

The invention is illustrated by examples of specific performance. The drawing shows a schematic diagram of the generator technetium-99M.

Extraction generator includes extraction column 1 with the cover 18 at the top to download irradiated molybdenum oxide. The pillar is in the center of the constriction with a printed label on it 5, a porous wall 20 at the bottom and two sizes: 19 to connect to the air-vacuum system and 4 to connect to the secondary column 6, which has the same design as the extraction column, with the difference that its upper part is tightly welded, and in the center of its narrower part of the introduced intake tube 11, wound the other end of the filter column 10, filled two-thirds of the volume of sorbent Al2O3. The lower pipe 7 additional column is connected to the drive 2, and through the valves B3and B4and with a capacity of 16 to collect waste within the protective chamber, which in turn is connected externally to the second part of the porous wall and the pipe for removal of the extractant with technetium in the evaporator 9. The evaporator has an outer casing for the supply of thermostat and hot water pipes in the upper part: 21 - for connection to the drive 8 with physiological NaCl, 22 for selection of technetium-99M into the tank 14 connected to the bottle (mi)-a collection of 15. The nozzle 23 of the evaporator is connected with the input end of the refrigerator 13, the casing of which is pumped cold water. The lower end of the refrigerator is connected to the tank 12 for collecting distilled extractant IEC. The tanks 12, 14, 15, 16, 17 are also connected through respective upper tubes to the air-vacuum system that is run from an external remote control 3. The remote control contains 10 solenoid valve, three of which (K3, K5and K7) are related through the air filter 24 with atmospheric air, and the other is connected to the vacuum pump 25 (e.g., water). The negative air pressure in the system is regulated by a needle valve and monitored by a pressure gauge. Valve and pressure gauge are located on the top cover of the remote control with rocker switch, push buttons which run certain solenoid valves.

Example 1. Neutron-irradiated reactor molybdenum oxide (MoO3) in an amount of 15 g with burned outside protective camera (in the diagram it is indicated by a double dashed line), in the extraction column predetermined amount 40 ml a B4and in the column creates a negative air pressure through the solenoid valve K1the total air-to-vacuum diagrams of the remote control 3. The alkaline solution is fed into the extraction column through the lower tube; the dissolution occurs MoO3followed by bubbling air from the drive 2. After the dissolution the same way in column 1 serves visivel 60 ml of a 4M solution of K2CO3and bring the level of the aqueous phase in the column to the mark 5 this same solution. In the drive 2 is injected 50 ml of methyl ethyl ketone and put it through the formed aqueous phase (EOF) as the previous solutions. IEC passing through the aqueous phase is collected in the upper part of the column above the EOF. Then generate a vacuum in the additional column 6 through the valve K2and in the extraction column through the valve K3connected with the atmosphere, run the air. Under the action of pressure drop content extraction columns goes into additional column through the lower pipe 7. In this column comes first EOF, and then through it again passes the same extractant. The process is carried out at an open valve on drive 8, BS sorbent Al2O310 and the intake pipe 11. This prevents the ingress of EOF and extractant in the filter column, and then when the solution level of the tip of the intake tube.

At the end of secondary extraction of the contents of the additional columns are transferred to the extraction column, and again after additional as described above. Thus carry out four extraction with the same volume of extractant. In the final translation solutions in an additional column mixture is allowed to settle for about 5 minutes until complete separation of the phases. If the EOF level is above the tip of the intake tube, part of the EOF is transferred to the extraction column through the pipe 7 and 4, close valve B4at the moment when the tip of the intake tube will be above the boundary line on 1 - 2 mm. If Vice versa, the EOF will be substantially below the tip of the intake tube due to the absorption of the extractant aqueous phase, an additional column through drive 2 enter a certain amount of water to achieve the desired level between the tip of the tube and the phase boundary 1 - 2 mm

After the establishment level in the system: collection IEC 12 - holodilnik 13 - evaporator 9 - column sorbische in an additional column. Due to this, the extractant through intake tube passes through the filter column and enters the evaporator, in the outer casing through which thermostat run hot water (t = 92 - 94oC). At the same time the casing of the refrigerator filled with cold water. The solvent is distilled off in the collection of the IEC, and on the inner walls of the evaporator remains technetium-99. The process of distillation are dry to prevent the ingress of methyl ethyl ketone in the product. After distillation in the drive when closed valve IN2enter 40 ml of isotonic 0.9% sodium chloride solution, open the valve and thereby translate this solution into the evaporator for flushing the dry residue of technetium-99M. This shuts off the hot water. Washing is conducted for 1 to 2 minutes, and then creating a vacuum through the valve TO a6in the vessel 14, transferred into it the resulting solution pertechnitat sodium. The process is carried out at an open valve IN2the drive 8. From the tank 14 with the help of micropipette take 5 ál of the resulting solution pertechnitat and measure its volume activity on gamma-spectrometer with semiconductor Ge(Li) detector. In the above example, it is equal to 30 MCI/ml, and the total activity of the drug is AITc= 1200 MkI. And the e through the valve TO a8.

Example 2. The selection of technetium-99M spend 22 hours (the period of accumulation of technetium-99M in the aqueous phase after the previous extraction) from the same solution EOF and the same as in example 1 with the difference that the extraction is carried out twice instead of 4 times, as in example 1. From the tank 14 selected sample pertechnitat 5 ál and measure the specific activity of the drug. She was 24.3 MCI/ml, and the total activity pertechnitat A2Tc= 970 MkI.

Example 3. The selection of technetium spend 44 hours after the first extraction as in example 1 with the difference that the extraction is performed 6 times. Select a sample pertechnitat and measure its volume activity. It is equal to 21.3 MCI/ml, respectively, of the total activity of the drug is A3Tc= 850 MkI.

After 14 days, when the level of activity of the parent isotope is reduced by more than 32 times, produce the recharge oscillator fresh batch of molybdenum-99. Thus the discharge of the aqueous phase is carried out additional columns with open valves IN3and IN4in the collection of waste 16 located in a protective camera. For this collection creates a vacuum through the valve TO a9and additional number is the 2. From the collection of 15 selected sample solution EOF and measure the specific activity of molybdenum 99 gamma-spectrometer with a view to subsequently calculate the initial (at the time of the first allocation, the activity of molybdenum in the aqueous phase and, accordingly, technetium-99 at the time of the first, the second in 22 hours, and the third with 44 hours of discharge. These data are needed to calculate the output of technetium-99M from generator. Outputtdefined as the ratio of the experimentally obtained values of the total activity of technetium-99M-AiTcwhen the i-th discharge to the calculated values of these quantities at the time of allocation of Atheory.. In this case, the specific activity99Mo was 18.3 MCI/ml, and shared AMo- 1830 MkI.

To calculate activities of technetium-99M based on the activity of molybdenum-99M at the time t, using the formula

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where1and2- constant radioactive decay of99Mo and99MTS.

Calculations by the formula shows that at the time of the first selection in the aqueous phase contained 1240 MCI of technetium-99M at the time of the second - 1082 MkI and third - 866 MkI. Accordingly, the product yield in examples 1, 2 and 3 was 97,90 and 98%. It follows that the dual extrac is then four times. I.e. the conditions of example 1 are optimal for the proposed method and device. In order to avoid overflow of the waste collection 16 periodically (about 1 every six months) to produce output of waste in the outer collector 17, which include the valve TO10(the negative pressure in the collection of 17) and open the gates IN1IN3IN4.

The proposed generator set is controlled by the system 10 solenoid valve located in the housing of the remote control from which the camera wound air-vacuum communication. The remote has 7 buttons-command and control manometer. For work enough dilution air, which provides laboratory water jet pump 18. The launch of the atmospheric air in the system through the air filter 19.

The inventive method and device provide trouble-free operation of the generator when the process of selection of the extractant in the evaporator, increase the efficiency of extraction and contribute to the reduction of system size 1.5 - 2 times compared with the known devices.

1. The method of extraction of receipt of technetium-99M, including loading, dissolved substances with the parent radionuclide99the IDT by alternately feed content extraction columns in the additional column and back, what in turn create a negative pressure in both columns, the selection of the extractant with technetium after the extraction is carried out additional columns through intake tube, creating a vacuum in the filter column - vaporizer - a collection of extractant.

2. The device for implementing the method of the extraction of receipt of technetium-99M, including the loading unit, the extraction column, evaporator, characterized in that it additionally contains a column with sorbent with a porous septum in the lower part, the capacity for pertechnitat sodium, site selection pertechnitat with a bottle collector and auxiliary containers with liquid and air-vacuum communications, the extraction column contains the scattering ring in the middle part and a porous membrane at the bottom, under which in the case of the column-mounted in the pipe, and a nozzle in the upper part of the column for connection to the air-vacuum system, in the middle part of the extraction column is narrowing with a printed label on it to control the level of the aqueous phase, while the extraction column to its lower pipe is connected through one-way valve with bottom outlet added columns, that is its top mounted intake tube, one end of which is located in the center of its narrower part, and the other opened into the column with sorbent and has at one end a conical spray.

3. The device according to p. 2, characterized in that the upper portion of the column tightly welded.

 

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