Claims
- 1. A generator of radionuclides comprising a generator column containing the radionuclide and provided with an inlet and outlet for eluent; a first reservoir containing a supply of eluent; a second reservoir of fixed volume for supplying to the column an adjustable predetermined volume of eluent; means connecting the first and second reservoirs whereby the second reservoir can be filled up from the first; means including valve means connecting an outlet of the second reservoir to the column inlet; means for rotatably mounting said second reservoir about a horizontal axis; and adjustment means for adjusting the angular position of said second reservoir about said axis to thereby vary the proportion of the total volume which lies above the outlet of the reservoir, to thus determine the amount of liquid dispensed from the reservoir when said valve means is opened, whereby a predetermined volume of the eluent can be caused to pass from the second reservoir through the column so as to elute the radionuclide therefrom under sterile conditions.
- 2. The generator as claimed in claim 1, including an evacuated vial connected to the outlet of the generator column.
- 3. The generator as claimed in claim 2, wherein the capacity of the evacuated vial is greater than the volume of the second reservoir.
- 4. The generator as claimed in claim 1 wherein the outlet is positioned in such a way that, in a first angular position of said second reservoir, the outlet is spaced a first vertical distance from the lowermost point of the reservoir and in a second angular position of said second reservoir, the outlet is spaced a second vertical distance from the lowermost point of the reservoir, said first distance being greater than said second distance whereby the amount dispensed upon opening of said valve means is greater when the second reservoir is in said second angular position.
- 5. The generator as claimed in claim 1, wherein the second reservoir is provided with an aperture provided with a hydrophobic filter permitting the passage of air but preventing the escape of liquid.
- 6. A method of generating a radionuclide under sterile conditions using a generator of radionuclides comprising a generator column containing the radionuclide and provided with an inlet and an outlet for eluent, a first reservoir containing a supply of eluent, a second reservoir of fixed volume for supplying to the column an adjustable predetermined volume of eluent, means connecting the first and second reservoirs whereby the second reservoir can be filled up from the first, means including valve means connecting an outlet of the second reservoir to the column inlet and means for rotatably mounting the second reservoir about a horizontal axis, said second reservoir being so shaped and arranged that, as it is rotated about said horizontal axis, that proportion of the total volume of the second reservoir which lies above the outlet is varied,
- which method comprises filling up the second reservoir from the first reservoir, adjusting the angular position of the second reservoir to a desired position, depending upon the volume to be dispensed, connecting an evacuated vial to the outlet of the generator column, and then opening said valve means so as to draw said predetermined volume of eluent in the second reservoir through the column and into the evacuated vial.
- 7. The method as claimed in claim 6, wherein the volume of the evacuated vial is greater than the predetermined volume of the eluent in the second reservoir, the method comprising, after the eluent has been drawn into the evacuated vial, the further step of drawing air through the column and into the vial by the partial vacuum in the vial so as to substantially dry the column and bring the vial to atmospheric pressure.
Priority Claims (1)
| Number |
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| 8303558 |
Feb 1983 |
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Parent Case Info
This application is a continuation of now abandoned application Ser. No. 576,405, filed Feb. 2, 1984, now abandoned.
This invention relates to generators for radionuclides of the kind in which a parent radionuclide, adsorbed on a column of particulate material, continuously generates by radioactive decomposition a daughter radionuclide which is periodically removed by elution from the column. This invention is mainly concerned with technetium generators, in which typically the parent radionuclide molybdenum-99 is adsorbed on a column of particulate alumina and the technetium-99m eluted using physiological saline solution. But as will appear, the invention is applicable in principle to generators of any radionuclide.
Commonly assigned co-pending European Patent Application No. 823021043 (publication No. 0068605) provides a generator of this kind comprising a generator column containing radionuclide and provided with an inlet and an outlet for eluent, a first reservoir for the eluent, a second reservoir to contain a variable pre-set volume of the eluent required for a single elution, means connecting the first and second reservoirs whereby the second reservoir can be filled up from the first, and means connecting the second reservoir to the column inlet whereby eluent can be caused to pass from the second reservoir through the column so as to elute the radionuclide therefrom. Preferred generators have the following advantages which cannot all be achieved simultaneously by any prior generator:
(i) The elution volume is easily variable through a wide range.
(ii) Elution is automatic; the operator does not have to be present.
(iii) Only a single vial, the collection vial, is needed for elution (single vial elution): some systems have required also the connection of a vial with a supply of eluent to the generator for each elution (dual vial elution).
(iv) The collection vial is only partly filled with liquid.
(v) The collection vial is at atmospheric pressure on completion of the elution process.
(vi) Excess liquid is removed from the column bed and from the connection lines, offering these advantages:
(a) Passage of air through the bed can be helpful in counteracting radiation chemistry effects which lower the elution yield of pertechnetate ion, Tc-99m, although other effective means exist of obviating this problem.
(b) If the system is designed to operate with the connection lines always full of liquid, there may be a need to "prime" the system before the first elution: this is an inconvenient step to manufacturer or user.
(c) In some systems designed to operate with the connection lines always full of liquid, there exists the possibility of unwanted expulsion of liquid from the lines because of, for example, generation of radiolytic gas in the column.
(vii) Only one size of collection vial and shield is required.
(viii) The generator column can be specially designed for activity to be elutable in a small volume.
(ix) The volume of eluate is not influenced by small changes in the degree of evacuation of the vial (e.g. as a result of air leakage into the vial).
The generator described in our European Patent Specification achieved these advantages by the use of a second reservoir which contained a variable pre-set volume of the eluent required for a single elution. Variable volume reservoirs have the disadvantage of being rather expensive, and this may be aggravated by the need to keep the contents in a sterile condition.
The present invention seeks to achieve the same advantages by a different approach, namely by providing a reservoir of fixed volume which delivers a variable volume of eluate determined by its orientation. Generators incorporating such reservoirs can be simpler and cheaper to manufacture, with fewer components, and in some cases simpler to operate. Rotation of the second reservoir lends itself to easier control from the working surface of the generator. In one embodiment, described below, the absence of relatively sliding parts eliminates microbiological problems.
The present invention thus provides a generator of radionuclides comprising a generator column containing the radionuclide and provided with an inlet and an outlet for eluent, first and second reservoirs for eluent, means connecting the first and second reservoirs whereby the second reservoir can be filled up from the first, and means connecting the second reservoir to the column inlet whereby a pre-determined volume of the eluent can be caused to pass from the second reservoir through the column so as to elute the radionuclide therefrom.
characterized in that a part defining the second reservoir is rotatable such that the orientation of the part determines the volume of eluent passed from the second reservoir through the column.
The second reservoir is of fixed volume. A part defining the reservoir, which part may be the whole reservoir, is rotatable. Depending on the orientation of that part, either the whole or a pre-determined fraction of the eluent in the second reservoir can be caused to pass through the generator column
An embodiment is described in which the whole second reservoir is rotatable about a horizontal axis, giving continuously variable volumes of eluent but requiring an external valve arrangement to control inlet and outlet of liquid.
The second reservoir is preferably provided with an aperture permitting the passage of air during filling and emptying but preventing the escape of liquid in normal operation and during transit. There are commercially available hydrophobic filters which perform this function.
Such a generator is particularly suitable for operation by vacuum elution, that is to say by connecting an evacuated vial to the outlet of the generator column so as to suck eluent from the second reservoir through the column. The provision of an aperture to the second reservoir, as noted above, can be used to cause air to be sucked through the generator column after the eluent, so as to remove excess liquid from the column bed and lines and leave the partly-filled vial at atmospheric pressure.
US Referenced Citations (11)
Continuations (1)
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576405 |
Feb 1984 |
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Patent Grant
4783305
