Method and device for producing 99mTc

Abstract

A method for producing .sup.99mTc may include: providing a solution comprising .sup.100Mo-molybdate-ions; providing a proton beam having an energy suitable for inducing a .sup.100Mo(p,2n).sup.99mTc-nuclear reaction when exposing .sup.100Mo-molybdate-ions; exposing the solution to the proton beams and inducing a .sup.100Mo(p,2n).sup.99mTc-nuclear reaction; and applying an extraction method for extracting the .sup.99mTc from the solution. Further, a device for producing .sup.99mTc may include: a solution with .sup.100Mo-molybdate-ions; an accelerator for providing a proton beam with energy which is suitable for inducing a .sup.100Mo(p,2n).sup.99mTc-nuclear reaction when exposing .sup.100Mo-molybdate-ions, for exposing the solution and for inducing a .sup.100Mo(p,2n).sup.99mTc-nuclear reaction; and an extraction step for extracting .sup.99mTc from the solution.

Claims

1. A method for producing .sup.99mTc, comprising: providing an aqueous solution comprising dissolved .sup.100Mo-molybdate ions, providing a proton beam having an energy suitable for inducing a .sup.100Mo(p,2n).sup.99Tc nuclear reaction when .sup.100Mo-molybdate ions are irradiated, irradiating the aqueous solution with the proton beam and inducing a .sup.100Mo(p,2n).sup.99Tc nuclear reaction, applying a solvent extraction method to dissolve the .sup.99Tc into solution with the solvent and separate a resulting .sup.99Tc-loaded solvent solution from the aqueous solution containing dissolved .sup.100Mo-molybdate ions.

2. The method of claim 1, wherein the extraction method comprises a solvent extraction method using methyl ethyl ketone.

3. The method of claim 1, comprising recycling dissolved .sup.100Mo-molybdate ions remaining in solution after the .sup.99Tc extraction to additional aqueous solution to be irradiated.

4. The method of claim 1, wherein the aqueous solution with dissolved .sup.100Mo-molybdate ions is an aqueous solution of a .sup.100Mo-molybdate salt, and wherein a nuclear reaction which leads to at least one cation end product is induced in the aqueous solution by irradiating cations of the .sup.100Mo-molybdate salt in solution with the proton beam.

5. The method of claim 4, comprising: after extracting the .sup.99Tc, recycling the remaining solution containing dissolved .sup.100Mo-molybdate ions to additional aqueous solution; and removing the at least one cation end product before returning to the aqueous solution.

6. The method of claim 4, comprising after extracting the .sup.99Tc from the aqueous solution, cleansing the extracted .sup.99mTc of impurities resulting from the nuclear reaction which leads to at least one cation end product.

7. The method of claim 4, wherein the .sup.100Mo-molybdate salt comprises .sup.6Li.sub.2.sup.100MoO.sub.4, and wherein the at least one cation end product comprises .sup.3H.

8. The method of claim 4, wherein the .sup.100Mo-molybdate salt comprises Na.sub.2.sup.100MoO.sub.4, and wherein the cation end product comprises .sup.18F.

9. The method of claim 4, wherein the .sup.100Mo-molybdate salt comprises K.sub.2.sup.100MoO.sub.4, and wherein the cation end product comprises Ca ions.

10. The method of claim 4, comprising after extracting the .sup.99mTc, returning the remaining dissolved .sup.100Mo-molybdate ions to the aqueous solution and removing the at least one cation end product using an ion exchanger.

11. The method of claim 4, comprising after extracting the .sup.99Tc from the aqueous solution, using an ion exchanger to cleanse the extracted .sup.99Tc of impurities resulting from the at least one cation end product.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Example embodiments will be explained in more detail below with reference to figures, in which:

(2) FIG. 1 shows the design of a device for producing .sup.99mTc from a lithium-molybdate salt, according to one embodiment,

(3) FIG. 2 shows the design of a device for producing .sup.99mTc from a sodium-molybdate salt, according to one embodiment, and

(4) FIG. 3 shows the design of a device for producing .sup.99mTc from a potassium-molybdate salt, according to one embodiment.

DETAILED DESCRIPTION

(5) Some embodiment provide a method and a device for the alternative production of .sup.99mTc.

(6) For example, in some embodiments a method for producing .sup.99mTc comprises: providing a solution with .sup.100Mo-molybdate ions, providing a proton beam with an energy suitable for inducing a .sup.100Mo(p,2n).sup.99mTc nuclear reaction when .sup.100Mo-molybdate ions are irradiated, irradiating the solution with the proton beam and inducing a .sup.100Mo(p,2n).sup.99mTc nuclear reaction, applying an extraction method for extracting the .sup.99mTc from the solution.

(7) Thus, the .sup.99mTc is obtained directly on the basis of a nuclear reaction which occurs as a result of the interaction of the proton beam with the molybdenum atoms, according to the equation .sup.100Mo(p,2n).sup.99mTc. The energy of the proton beam is greater than 20 MeV and is therefore in a range in which the effective cross section for the aforementioned nuclear reaction lies. As a result, .sup.99mTc atoms can be obtained in a number that is sufficient for the production of .sup.99mTc. As a result of the fact that the molybdenum atoms are present as molybdate ions in a solution, the resultant .sup.99mTc can subsequently be extracted from the solution in a simple manner with the aid of an extraction method. The extracted .sup.99mTc can then be used for different purposes, in particular for producing a radionuclide for SPECT imaging.

(8) The proton beam is accelerated to an energy of at least 20 MeV. The particle beam may be accelerated to an energy of 20 MeV to 25 MeV. Restricting the maximum energy to no more than 35 MeV, more particularly to 30 MeV and most particularly to 25 MeV avoids nuclear reactions leading to undesired reaction products, e.g. Tc isotopes other than .sup.99mTc, being triggered as a result of a particle beam with too high an energy, which would then again require an additional step by means of which the undesired reaction products are removed again. The chamber in which the solution with molybdate ions is contained can be designed or dimensioned such that the emerging particle beam has an energy of at least 10 MeV. In this manner, the energy range of the proton beam can be kept in a range in which the occurring nuclear reactions remain controllable and in which undesired reaction products merely occur to an acceptable extent.

(9) Accelerating protons to the aforementioned energy usually requires only a single accelerator unit of average size, which can also be installed and used locally. Using the above-described method, .sup.99mTc can be produced locally in the vicinity or in the surroundings of the desired location of use, for example in a hospital environment. In contrast to conventional, non-local production methods which are accompanied by the use of large installations such as in nuclear reactors and the distribution problems connected therewith, local production solves many problems. Nuclear medicine units can plan their workflows independently from one another and are not reliant on complex logistics and infrastructure.

(10) In one embodiment, the extraction method can be a liquid-liquid extraction method, more particularly using methyl ethyl ketone.

(11) This extraction method is suitable because .sup.99mTc is present in a solution. The .sup.99mTc dissolves in methyl ethyl ketone, with the molybdate ions continuing to remain in the aqueous solution. This makes it possible to separate the .sup.99mTc from the .sup.100Mo. The .sup.99mTc-loaded methyl ethyl ketone can e.g. be dried such that the .sup.99mTc can subsequently be used e.g. for producing a radiopharmaceutical.

(12) In one embodiment, the dissolved .sup.100Mo-molybdate ions remaining after the .sup.99mTc extraction can be returned to the solution to be irradiated, for example in a closed loop. This may ensure that the parent material, namely the .sup.100Mo-molybdate ions, is used particularly efficiently.

(13) In one embodiment, the solution with .sup.100Mo-molybdate ions is a solution of a .sup.100Mo-molybdate salt, wherein a nuclear reaction which leads to at least one cation end product is induced in the solution by irradiation with the proton beam at the cations of the .sup.100Mo-molybdate salt, said reaction more particularly leading to a cation end product, which was not present in the original solution to be irradiated, which is an ion which is unstable and/or which is potentially harmful to the human body. The term cation end product does not necessarily mean that the end product has to be a cation, it merely denotes the fact that the end product originates from the cations of the salt.

(14) In this case, the remaining, dissolved .sup.100Mo-molybdate ions can be returned to the irradiating solution after extracting the .sup.99mTc, wherein the at least one cation end product is removed before the supply, more particularly by using an ion exchanger.

(15) This embodiment can be advantageous in that the solution returned to the solution to be irradiated contains no constituents which, in the case of renewed irradiation by the proton beam, would lead to further irradiation products that differ from the cation end products. By way of example, it is then possible to avoid cation end products being supplied to the solution which, in the case of irradiation, would lead to further, new nuclear reactions. This makes it possible to avoid uncontrolled or unmanageable nuclear reactions despite the return of the molybdate ions.

(16) In one embodiment, the extracted .sup.99mTc can be cleansed of impurities resulting from the cation end product, more particularly by using an ion exchanger.

(17) This makes it possible, for example, to remove potentially undesired constituents of the extracted .sup.99mTc solution before further processing. Thus, for example, it is possible to remove potential substances which are toxic to the human body prior to the production of the radionuclide or other radionuclides with a different half-life.

(18) In one embodiment variant, the .sup.100Mo-molybdate salt comprises .sup.6Li.sub.2.sup.100MoO.sub.4. .sup.6Li decays by the nuclear reaction .sup.6Li(p,3He).sup.4H to .sup.4H, which in turn immediately decays to tritium.

(19) If .sup.7Li were used, the bombardment by the proton beam would trigger the reaction .sup.7Li(p,n).sup.7Be, with the .sup.7Be having to be removed again. The use of .sup.6Li avoids this.

(20) As a result of this, no cation end product is created which, in the case of renewed irradiation by the proton beam, would lead to an uncontrolled chain of nuclear reactions. The cleaning stage, by means of which the cation end product being created is removed, can optionally be dispensed with.

(21) In another embodiment variant, the .sup.100Mo-molybdate salt comprises Na.sub.2.sup.100MoO.sub.4. Here, the at least one cation end product comprises .sup.18F. Naturally occurring .sup.23Na is converted into .sup.23Mg by bombardment with the proton beam as a result of the reaction .sup.23Na(p,n).sup.23Mg, with said .sup.23Mg in turn quickly decaying to .sup.23Na. A further nuclear reaction is .sup.23Na(p,x).sup.18F. Overall, .sup.18F is now also present as a cation end product after the irradiation, said .sup.18F not having been present in the original solution. The .sup.18F can be removed with the aid of an ion exchanger, for example from the solution which contains the .sup.99mTc after the extraction of .sup.99mTc or from the solution which contains the remaining molybdate after the extraction of .sup.99mTc and which is returned to the original solution. As a result, this avoids the irradiation of .sup.18F and the return loop triggering a chain of nuclear reactions which are difficult to control.

(22) In a further embodiment variant, the .sup.100Mo-molybdate salt comprises K.sub.2.sup.100MoO.sub.4, with the cation end product comprising .sup.41Ca. Naturally occurring .sup.41K is converted by the proton beam in the following nuclear reactions: .sup.41K(p,n).sup.41Ca, .sup.41K(p,).sup.42Ca, .sup.41K(p,).sup.38Ar. .sup.39K, which likewise occurs naturally, is converted by the proton beam in the following nuclear reactions: .sup.39K(p,d).sup.38K, .sup.39K(p,).sup.40Ca. .sup.38K decays to .sup.38Ar. Of all the Ca ions created, only .sup.41Ca is unstable. All ions can be removed by the ion exchanger. Returning .sup.38Ar is uncritical because the interaction cross section for the interaction with the proton beam is in a different region than the interaction cross section for the .sup.100Mo(p,2n).sup.99mTc nuclear reaction. Returning and irradiating .sup.38Ar therefore does not create a nuclear reaction chain with uncontrollable end products.

(23) In some embodiments, a device for producing .sup.99mTc comprises: a solution with .sup.100Mo-molybdate ions, an accelerator for providing a proton beam with an energy suitable for inducing a .sup.100Mo(p,2n).sup.99mTc nuclear reaction when .sup.100Mo-molybdate ions are irradiated, for irradiating the solution and for inducing a .sup.100Mo(p,2n).sup.99mTc nuclear reaction, an extraction stage for extracting the .sup.99mTc from the solution.

(24) In one embodiment variant, the solution with .sup.100Mo-molybdate ions is a solution of a .sup.100Mo-molybdate salt, wherein a nuclear reaction which leads to at least one cation end product is induced in the solution by irradiation with the proton beam at the cations of the .sup.100Mo-molybdate salt and wherein the device additionally has a first cleaning stage downstream of the extraction stage, in which cleaning stage the extracted .sup.99mTc can be cleansed of impurities resulting from the cation end product.

(25) In one embodiment variant, provision is made for a loop, by means of which the dissolved .sup.100Mo-molybdate ions of the solution to be irradiated, which remain after the extraction of .sup.99mTc, can be resupplied, for example via a closed loop. More particularly, if the solution with .sup.100Mo-molybdate ions is a solution of a .sup.100Mo-molybdate salt, the device can additionally have a cleaning stage, interposed into the loop, in which the at least one cation end product is removed, more particularly by using an ion exchanger, before the remaining, dissolved .sup.100Mo-molybdate ions are supplied.

(26) According to the embodiment of FIG. 1, an aqueous solution 11 is initially provided, in which .sup.6Li.sub.2.sup.100MoO.sub.4 is dissolved.

(27) The solution 11 is subsequently routed to an irradiation chamber 13, which is irradiated by a proton beam 15 which is generated by an accelerator unit 17 such as e.g. a cyclotron. Here, the proton beam 15 has an energy of 20 to 25 MeV on entry into the irradiation chamber 13, and an energy of approximately 10 MeV upon exit. In this energy range, the proton beam 15 interacts with the .sup.100Mo and partly converts the latter directly into .sup.99mTc in a nuclear reaction, on the basis of the nuclear reaction .sup.100Mo(p,2n).sup.99mTc.

(28) As a result of irradiating the .sup.6Li ions, the following nuclear reactions also occur: .sup.6Li(p,3He).sup.4H, with .sup.4H immediately decaying to tritium.

(29) The irradiated solution is routed to a chamber 19 for solvent extraction, in which the .sup.99mTc is extracted from the aqueous solution with the aid of MEK (methyl ethyl ketone). The .sup.99mTc dissolved in MEK can then be processed further, for example in a subsequent pharmaceutical module (not illustrated).

(30) The remaining solution of the molybdate salt is returned to the originally provided solution 11.

(31) The embodiment in FIG. 2 differs from FIG. 1 by virtue of the fact that an aqueous solution 21 is initially provided, in which Na.sub.2.sup.100MoO.sub.4 is dissolved.

(32) As a result of irradiating the Na ions, the following nuclear reactions occur: .sup.23Na(p,n).sup.23Mg and .sup.23Na(p,x).sup.18F. .sup.23Mg in turn decays to stable .sup.23Na. By contrast, .sup.18F is radioactive.

(33) The irradiated solution is routed to a chamber 19 for solvent extraction, in which the .sup.99mTc is extracted from the aqueous solution with the aid of MEK (methyl ethyl ketone). Prior to further processing, impurities resulting from the .sup.18F can be removed with the aid of a first ion exchanger 23.

(34) .sup.18F can likewise be removed with the aid of a further ion exchanger 25, before the solution of the molybdate salt remaining after the .sup.99mTc extraction is returned to the originally provided solution 21.

(35) The extracted .sup.99mTc solution 27, which has been cleansed of .sup.18F, can then for example be made available in a subsequent pharmaceutical module.

(36) The embodiment in FIG. 3 differs from FIG. 1 by virtue of the fact that an aqueous solution 31 is initially provided, in which K.sub.2.sup.100MoO.sub.4 is dissolved.

(37) As a result of irradiating the K ions, the following nuclear reactions occur: .sup.41K(p,n).sup.41Ca, .sup.41K(p,).sup.42Ca, .sup.41K(p,).sup.38Ar, .sup.39K(p,d).sup.38K, .sup.39K(p,).sup.40Ca. Of all the cation end products which are being created, only .sup.41Ca is unstable.

(38) The irradiated solution is routed to a chamber 19 for solvent extraction, in which the .sup.99mTc is extracted from the aqueous solution with the aid of MEK (methyl ethyl ketone).

(39) Prior to further processing, impurities resulting from the .sup.41Ca can be removed with the aid of a first ion exchanger 33.

(40) The .sup.41Ca and the other Ca ions can likewise be removed with the aid of a further ion exchanger 35 before the solution of the molybdate salt remaining after the .sup.99mTc extraction is returned to the originally provided solution 31.

(41) The extracted .sup.99mTc solution, which has been cleansed of .sup.41Ca, can then for example be dried in a dryer unit 37 and be made available in a subsequent pharmaceutical module (not illustrated).

LIST OF REFERENCE SIGNS

(42) 11, 21, 31 Aqueous solution 13 Irradiation chamber 15 Proton beam 17 Accelerator unit 19 Chamber for solvent extraction 23, 33 First ion exchanger 25, 35 Further ion exchangers 27 Cleansed .sup.99mTc solution 27 29 Dryer device