Extraction-chromatographic generator of technetium-99m. principles of functioning and exploiting conditions

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Proceedings o f the Third Eurasian Conference “Nuclear Science and its Application”, October 5 - 8 , 2004.

EXTRACTION-CHROMATOGRAPHIC GENERATOR

OF TECHNETIUM-99m. PRINCIPLES OF FUNCTIONING AND

EXPLOITING CONDITIONS

Skuridin V., Chibisov E., Nesterov E.

Nuclear Physics Institute, Tomsk, Russia

The radiopharmaceutical tracers, based on the short-lived radionuclide of Technetium-99m, are used for disease diagnostics practically of all important perts of human body. Technetium- 99m is a daughter product of the Molybdenum-99P - decay. The generating plants are used for division of the "M o / " mTc pair, where Technetium-99m uptake happens every 22 hour. Depending on the operation technique, the " mTc generators can be subdivided into 4 basic types: chromatographic (sorption), sublimation, extraction and gel generators. The advantage of the extraction technologies is in their concentrating capabilities and the high activity " mTc concentration from the underactive 99Mo. At the same time, nowadays the utilization of the extraction generators in clinical practice is limited because of their large sizes, control complexity and the need of using the heavy protective equipment. That’s why the problem of compact extraction generator creation, for using in radiologic laboratories, deals with the problem of their structure simplification, reducing sizes of extractor and with simultaneous refusing of the evaporating technology at the stage of Technetium separation from an exragent. It is well known [1,2], the most of the extraction vessels need a visual and other control of phases division position, during the realization of extraction and further extract selection. It leads to a necessity of using the bulky protective equipment for staff protection.

The generator [3] represents a compact stationary plant, composed of 3 principal blocks: a generator’s stand, a remote-control station and the extractor with Molybdenum-99 solution cased into a shielding container (Picture 1). The basis of this plant is the coaxial type extractor 1, in which the multiple extraction principle is realized. A self-regulation of an interface of the organic and aqueous phase reaches due to the mass conservation Law. It allows exploiting it as a “black box”. The extractor is 110 mm of height and 40 mm in diameter. A useful capacity of aqueous phase comes to 80 ml, of the organic phase - 60 ml. A transportation of the extractor with the solution K299Mo04 is realized in closed shielding container 2. In a clinic the extractor links up the stand with the evaporator 3 and the remote-control station 4. The preparation is processed within 90 min, 30-40 min of which takes distillation of the extragent. The plant is calculated on a charge of 55 GBq "Mo.

Fig.l. The design of the compact Technetium-99m extraction generator with a transportable

extractor.

Section IV. Application o f Nuclear Technologies in Industry, Medicine and Agriculture

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For decreasing the time of getting the preparation, the generator with chromatographic separation of " mTc was developed (Picture 2). Toward this aim, column 5, containing aluminium oxide with specific pH-form, was included instead of the evaporator.

The introduction of the column required decreasing of capacity of MEK in comparison with the previous plant. At the same time, the model calculations [4] showed that a capacity correlation of the organic and aqueous phase must be no less than 1 in order to achieve high efficiency of the extraction.

Fig-2. The designn of the compact extraction - chromatographic generator of Technetium-99m.

Thus, we developed the generator with phases correlation of 1:1 at their common volume to 40 ml. The size and mass of protective and transport containers were decreased. After the extraction, MEK with Technetium-99m passes through the column 4 for intercepting Molybdenum tracks and than comes in the column 5, where Technetium-99m sorbs. The spent MEK is accumulated in capacity 6. An elution of " mTc out of the column 5, after water wash, is realized with physiological solution into bottles 7.

Giving a work-out to operative conditions some important modifications in the construction of extraction - chromatographic plant were done (Picture 3). The column 4, the part of lacking apparatus and auxiliary capacities were moved off.

Fig.3. The design of the streamlined compact extraction - chromatographic Technetium-99m

generator. 280

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These modifications resulted in the decrease of in-process loss of Technetium-99m, an essential simplification of the apparatus design and of the generator’s exploitation conditions. The primary processing and exploiting characteristics of the presented generators are given in the Table 1.

Table 1.

Processing and exploiting characteristics of the generators of Technetium-99m.

Generator’s type Extractor

dimensions, mm Aqueous phase capacity, ml MEK capacity, ml Preparation time, h. Yield of 99nirr Tc, % Extraction 40x110 80 to 60 1,5 to 60 Extraction - chromatographic 20x100 20 to 20 to 0,5 to 76 Extraction -chromatographic (streamlined) 20x100 20 to 20 to 0,5 to 85 REFERENCES

1. Boyd R.E. Technetium Generators: Status and Prospects. // Seminar on Radionuclide Generator Technology, Vienna, Austria, Oct. 13-17 1986, IAEA. - p. 11-23.

2. Melichar F.,Sloboda K., Prokop I , Budsky F. Experience in Utilisation of the WWR-S Reactor with Medium Neutron Flux Intensity for " mTc Production in Czechoslovakis. // Seminar on radionucliede generator technology, Vienna, Austria, Oct. 13-17, 1986, IAEA- SR-131/50.

3. Extraction generator of Technetium-99m. Patent 2161132 RU. MKI C01G 57/00 // V. Skuridin, E. Chibisov. - Application. 14.02.00; Published 27.12.00.- Bulletin JV° 36.

4. Extractor with self-regulating phase division level. Patent 2234967 RU. MKI C01G 57/00 // V. Skuridin, E. Chibisov, E. Nesterov. - Application. 04.08.03; Published 27.08.04.- Bulletin M 24.

Section IV. Application o f Nuclear Technologies in Industry, Medicine and Agriculture