JP2966521B2 - Soluble irradiation target and manufacturing method of radioactive rhenium - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to the field of neutron irradiation for producing therapeutic and diagnostic radionuclides. In particular, the present invention relates to rhenium-
An improved irradiation target for producing 186 and rhenium-188.

BACKGROUND OF THE INVENTION Rhenium isotopes have recently gained interest in the nuclear medicine community for diagnostics and therapeutics. The two rhenium isotopes, ¹⁸⁶ Re and ¹⁸⁸ Re, are of particular interest only because they are suitable for therapeutic and diagnostic uses. ^The half-life of both ¹⁸⁶ Re and ¹⁸⁸ Re is relatively short (90 hours for ¹⁸⁶ Re, 16.98 hours for ¹⁸⁸ Re)
Emissive radionuclide (β energy is 1.07Mev,
2.12Mev). In addition, both exhibit β-release suitable for β-counters imaging biodistribution (9.
2%, 137 kev and 15%, 155 kev).

¹⁸⁶ Re is ¹⁸⁵ Re due to neutron capture in conventional reactors.
(37% natural abundance). The core properties of this isotope are as follows: ^In the production of ¹⁸⁶ Re, it is common to irradiate the metal rhenium-185 for more than 24 hours at a high neutron flux rate of 10 ¹⁴ -10 ¹⁵ neutrons / cm ² / s. After irradiation, the resulting ¹⁸⁶ Re isotope needs to be solubilized for clinical purposes, such as conjugation to a tumor-specific antibody, and is typically treated with a strong oxidizing agent, such as hydrogen peroxide or concentrated nitric acid. To obtain a soluble perrhenate solution.

The perrhenate solution containing ¹⁸⁶ Re must then be neutralized and purified to remove contaminants prior to antibody conjugation and / or other clinical use.

¹⁸⁸ Re is produced from natural rhenium-187 (63% natural abundance) in the form of carrier addition by neutron bombardment in conventional reactors, or neutron flux from a generator consisting of target tungsten material, preferably enriched in ¹⁸⁶ W ¹⁸⁸ W and its decay products due to double neutron capture in the reactor
Manufactured in the form of ¹⁸⁸ Re without carrier with high specific activity. The core properties of this isotope are as follows: ¹⁸⁸ Re produced from neutron capture by irradiation of ¹⁸⁷ Re is free of unconverted ¹⁸⁷ Re and other impurities (ie, obtained in the form of carrier addition), and has a short half-life of ¹⁸⁸ Re which is relatively long. Nucleolysis to reduce carrier accumulation in the tungstate / rhenium generation system to limit the ¹⁸⁸ Re accumulation efficiency during irradiation and subsequent processing
It is highly preferred to produce ¹⁸⁸ Re.

Known tungsten / rhenium generators for producing ¹⁸⁸ Re consist of a small alumina column and a relatively small amount of tungsten target adsorbed on the column, thus resulting in low rhenium yield and microcurie (μC
i) degree. To increase the amount of rhenium obtained from such a column (ie, millicurie mCi
To this end, it is necessary to enlarge the column to contain a large amount of target tungsten. Larger columns require larger elution volumes. Moreover, the known ¹⁸⁸ W / ¹⁸⁸ Re generator using an alumina column has a low ¹⁸⁸ Re yield, and it is necessary to adsorb a large amount (0.5 to 2.0 g) of target tungsten (mainly ¹⁸⁶ W) on the alumina column. Above, there was a problem with the release or "breakthrough" level of ¹⁸⁸ Re from the column.

U.S. Pat. No. 4,859,931 to Ehrhardt teaches that an insoluble zirconium tungstate matrix containing ¹⁸⁸ W collapses over time to produce ¹⁸⁸ Re in the form of perrhenate ( ¹⁸⁸ ReO ₄ ⁻ ) that is easy to elute from the matrix. Improved ¹⁸⁸
A Re generator is disclosed. The zirconium tungstate matrix disclosed in the Ehrhardt patent dissolves irradiated tungsten trioxide in a heated basic solution and adds ¹⁸⁸ W to the acidic zirconium-containing solution by adding the basic tungsten trioxide solution. It is produced by obtaining an acidic zirconyl tungstate slurry, drying the slurry to form a permeable matrix, and packing the matrix into an elution column. Eh
The rhardt generator has proven to be a very effective ¹⁸⁸ Re generator.

Linear irradiation of ¹⁸⁵ Re is effective for manufacturing ¹⁸⁶ Re, and ¹⁸⁷ Re
Linear irradiation and zirconyl tungstate generator method
^Although proven effective in producing ¹⁸⁸ Re, these methods have inherent drawbacks that limit mass production and quality. ^For direct irradiation of ¹⁸⁵ Re or ¹⁸⁷ Re, irradiated ¹⁸⁶ Re or in the form of rhenium metal or rhenium trioxide
¹⁸⁸ Re must be solubilized, typically by oxidation with concentrated nitric acid, to form a soluble perrhenate (ReO ₄ ⁻ ). The perrhenate solution must then be neutralized, for example, with aqueous ammonia. This method is time consuming, requires cumbersome treatment of the irradiated material, and involves unnecessary by-products that must be separated from the perrhenate. Known methods for producing tungsten / rhenium for producing ¹⁸⁸ Re are also complicated in the treatment of irradiated materials, for example, dissolution, precipitation, filtration, drying, gel refinement, column packing, and the like. This must be done after the irradiation of the tungsten or tungsten trioxide raw material. These treatments on irradiated materials require complex shielding treatment equipment, resulting in relatively high manufacturing costs and increased safety risks.

U.S. Pat. No. 4,778,672 to Deutsch et al. Discloses a method for purifying irradiated perrhenate and tungstate solutions primarily to remove contaminants resulting from the conditions required for target dissolution. Deutsch et al. Dissolve irradiated metal rhenium by adding concentrated nitric acid,
This solution is neutralized with ammonia. The neutralized solution containing the solubilized perrhenate is then treated with a soluble lipophilic counterion, such as tetrabutylammonium bromide, and is passed from a solution by passing through a priority sorption column previously treated with the counterion. The perrhenate is separated. The perrhenate separated from the unwanted by-products formed in the rhenium dissolution step is eluted from the column. The method can also be used to purify pertechnetate eluent from a molybdenum-99 / ecnetium-99m generation column or perrhenate eluate from a tungsten-188 / rhenium-188 generation column. The method of the Deutsch patent has been demonstrated to be effective in removing impurities from pertechnetate and perrhenate solutions. However, this method is time consuming and further exacerbates the cost and other problems associated with processing irradiated material. These problems are particularly acute with regard to the production of ¹⁸⁶ Re. That is, since ¹⁸⁶ Re has a relatively short half-life and is manufactured by direct irradiation, it is often necessary to treat the ¹⁸⁶ Re into an appropriate form in a hospital facility.

^99m T in molybdenum / technetium generation system
To omit some processing steps on the irradiated material in connection with the production of c, Narasimhan et al.
or ^99m Tc Generator Preparation, "J.Radioanal.Nuc
l. Chem., Letters, Vol. 85, No. 6, pp. 345-356, discloses an improved process for producing a ^99m Tc generator of zirconium molybdate, in which the process is similar to the known zirconium molybdate generation system. Direct irradiation of zirconium molybdate, rather than irradiation of molybdenum trioxide, avoids the precipitation, filtration, drying and micronization of radioactive materials required for preparing a ^99m Tc generator of zirconium molybdate. However, direct irradiation of zirconium molybdate, as reported by Narasimhan et al., Results in radioactive contaminants, such as ⁹⁷
Zr, ⁹⁵ Zr, ¹⁷⁵ Hf, ¹⁸¹ Hf, ²⁴ Na were produced.

Therefore, the ¹⁸⁶ Re and ¹⁸⁸ Re have been modified to facilitate dissolution of the radionuclide or its precursor and to reduce the processing, cost and safety risks for manufacturing into a form suitable for diagnostic or therapeutic use. It is strongly desired to realize an irradiation target for manufacturing.

SUMMARY OF THE INVENTION By directly irradiating a specific water-soluble irradiation target, which is selected on the condition that it is water-soluble and that there are no elements that produce unsuitable contaminating isotopes for therapeutic and diagnostic purposes, ¹⁸⁶ Re and It has been found that the above problems associated with the conventional production method of ¹⁸⁸ Re can be significantly reduced. In one embodiment of the present invention, ¹⁸⁶ Re is produced by directly irradiating a water-soluble irradiation target containing ¹⁸⁵ Re. Preferred targets include aluminum perrhenate, lithium perrhenate, and magnesium perrhenate. In another embodiment of the present invention, ¹⁸⁸ Re can be produced by directly irradiating soluble aluminum perrhenate, lithium perrhenate or magnesium perrhenate containing ¹⁸⁷ Re. In yet another embodiment of the present invention, a soluble irradiation target containing ¹⁸⁶ W is irradiated, the irradiated target is dissolved in an aqueous solution, and the dissolved target is reacted with an aqueous solution containing zirconyl ions to form an insoluble zirconyl tungstate precipitate. A zirconyl tungstate generator containing ¹⁸⁸ W for ¹⁸⁸ Re production is obtained by forming and storing this precipitate in an elution vessel. Preferred irradiation targets include sodium tungstate and lithium tungstate. In any of the examples, the irradiation target is easily dissolved in the aqueous solution, without performing complicated dissolution, neutralization, purification, etc. treatment on the irradiated material unique to the known ¹⁸⁶ Re and ¹⁸⁸ Re production methods, and the solution is left as it is after irradiation. In the form of, for example, it can be used for ligand conjugation for the purpose of diagnosis or treatment.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an improved rhenium irradiation target for use in the production of radionuclides ¹⁸⁶ and ¹⁸⁸ Re. Preferred irradiation targets that can be used in the present invention are water-soluble, and there are no elements that produce contaminating isotopes simultaneously with irradiation that would prevent the use of the required radionuclide ¹⁸⁶ Re or ¹⁸⁸ Re for treatment or diagnosis. Is selected on the condition that As used herein, the term "soluble" refers to compounds that have relatively high water solubility. The soluble irradiation target of the present invention has a water solubility of at least about 1000 g /, more preferably about 3000 g /. The irradiation target is selected on the condition that there is no element that generates a radioisotope that interferes with or contaminates the required ¹⁸⁶ Re or ¹⁸⁸ Re radionuclide with irradiation.

Preferred soluble irradiation targets for direct irradiation in the production of ¹⁸⁶ Re or ¹⁸⁸ Re include aluminum perrhenate, lithium perrhenate, and magnesium perrhenate. The most preferred soluble irradiation target is aluminum perrhenate. ¹⁸⁶ R expected radionuclide
If e, the irradiation target is preferably concentrated in ¹⁸⁵ Re. Similarly, if the intended radionuclide is ¹⁸⁸ Re, it is preferable to concentrate the target in ¹⁸⁷ Re. If lithium perrhenate is used as the irradiation target, ⁶ Li
In order to avoid undesirable by-products such as tritium associated with neutron capture by
Also concentrated in ⁷ Li. Preferred targets for use with a ¹⁸⁸ W containing tungsten / rhenium generator for ¹⁸⁸ Re production include sodium tungstate and lithium tungstate, with sodium tungstate being most preferred. Particularly preferred targets will concentrate in ¹⁸⁶ W and, if composed of lithium, will also concentrate in ⁷ Li.

The soluble irradiation target of the present invention can be obtained by dissolving metal rhenium, metal tungsten, or rhenium trioxide or tungsten by a known method. For example, metal rhenium may be dissolved in concentrated nitric acid or hydrogen peroxide solution, and metal tungsten may be dissolved in concentrated nitric acid or hydrofluoric acid. The acidic mixture is then dried to volatilize undesired components, such as HF (if present), and water is again added to an aqueous solution. This solution containing perrhenate or tungstate is mixed with an aqueous solution of the required counterion. The mixed solution is dried by heating to collect a soluble irradiation target in a dry form. If necessary, the irradiation target may be redissolved in, for example, water, purified by filtration or the like, dried by heating, and further purified by one or several washing steps. The recovered solid substance may be directly irradiated in a neutron reactor in a known manner.

The present invention provides an improved radionuclide comprising irradiating a water-soluble irradiation target containing ¹⁸⁵ Re or ¹⁸⁷ Re, respectively, and dissolving the irradiated target in an aqueous solution.
We also provide ¹⁸⁶ Re or ¹⁸⁸ Re recipes. Rather than irradiating metal rhenium or rhenium trioxide as in the known production method, by directly irradiating the water-soluble irradiation target, the complicated purification and treatment of the irradiated material unique to the conventional rhenium radionuclide production method are significantly increased. It is reduced.

The present invention provides a step of irradiating a soluble target selected from sodium tungstate or lithium tungstate containing ¹⁸⁶ W to obtain an irradiated soluble tungstate containing ¹⁸⁸ W, reacting the soluble tungstate with an aqueous zirconium solution. There is also provided a method of making an improved tungsten / rhenium generator for the production of ¹⁸⁸ Re which involves obtaining an insoluble zirconium tungstate gel or matrix and then placing the zirconium tungstate gel in an elution vessel. . The production by the generator of the present invention is performed by using a known zirconyl tungstate.
It is much more advantageous than the method using a gel matrix type generation system. Because a soluble irradiation target is directly irradiated, easily solubilized and reacted with zirconium ions to form an insoluble zirconium tungstate gel and packed in a column, which requires a production method using a known generation system. This is because complicated steps such as dissolution and purification of nitric acid and hydrofluoric acid for the irradiated material can be avoided. Preferably, the soluble irradiation target is a dried solid which is convenient for direct irradiation. After irradiation, if present, ¹⁸⁷ (half-life 24 hours)
And ²⁴ Na (having a half-life of 15 hours) are preferably allowed to disintegrate from the irradiated material, by dissolving the irradiated target in water, for example by reacting with zirconyl nitrate, insolubilizing, packing in a column and disintegrating. Form highly soluble ions containing ¹⁸⁸ Re, typically perrhenate ( ¹⁸⁸ ReO ₄ ⁻ ). The ¹⁸⁸ ReO ₄ ^- it can be easily eluted from the column.

In this generator embodiment, the zirconium tungstate matrix is transferred to an empty container to elute and recover the perrhenate containing ¹⁸⁸ Re. A suitable container is, for example, a glass column as used in standard chromatography, which is packaged in a "shell" containing appropriate lead shielding, associated lead tubes, and eluent and tank. Rarely forms a generator assembly. Separate tanks sterilized for each elution operation may be used. Although not a prerequisite, it is desirable that the matrix be kept hydrated at all times. It is advantageous to elute the daughter radionuclide periodically using a suitable eluent such as water or saline. A particularly preferred eluent is physiological saline.

The performance of the improved generator of the present invention can be described by its elution efficiency. Elution efficiency can be calculated by dividing the activity level of the daughter radionuclide present in the eluate by the activity level of the daughter radionuclide present on the generator column immediately before elution. The radionuclide activity can be measured using a gamma-ray spectrophotometer such as a germanium detector or sodium iodide scintillation spectrophotometer that can measure low levels of radioactivity, or a dose calibrator that can measure high levels of radioactivity. The measurement may be performed using such a standard radioactivity measuring instrument. In the present invention, since the generator consists of a small column, the whole column can be placed in the dose calibrator to directly measure the radioactivity of the daughter radionuclide in the column before elution, and the daughter in the column after elution. By subtracting the amount of radioactivity of the radionuclide from this value, the radioactivity of the radionuclide present in the eluate can be determined. In this method, the radioactivity measured on the column can be attributed to the daughter radionuclide if the dose calibrator is set appropriately, so that a value very similar to the daughter radionuclide present in the eluate can be obtained. Can be Elution efficiencies are usually measured after about 3 to 10 daughter radionuclide half-lives. Using the generator of the present invention, high elution efficiencies of 55% to 65% have been obtained, and the ¹⁸⁸ Re concentration in the eluent measured immediately after elution and typically after 3 or 4 half-lives.
It is more than 30m Ci / ml.

The radiochemical purity of the daughter radionuclide can be assessed by ion-exchange reversed-phase high-performance liquid chromatography (HPLC) or scintillator chromatography using non-radioactive perrhenate as a standard.

During the elution process, a certain amount of the radioactive nuclide may be released into the eluate, for example in the form of zirconium tungstate fine particles, to contaminate the daughter radionuclide. By utilizing a porous glass or plastic structure, such as a fritted glass disk used in chromatography columns, some of these particles can be retained to prevent tungsten from entering the eluent. However, if the production method of the present invention is adopted, most of the generator matrix is dissolved before a considerable part of the radionuclide contained in the generator matrix is released, so that the radioactive radioactivity released from the column is released. The amount of nuclide is relatively small (0.01%). In addition, the level of the radionuclide present in the eluent can be reduced by several orders of magnitude by using an adsorbent capable of absorbing the radionuclide, such as an alumina column or a zirconium hydroxide bed, to reduce the eluate from the generator. It can be purified. That is, the generation scheme of the present invention includes, in addition to the vessel surrounding the generator matrix, a second elution vessel, such as a chromatographic column surrounding a second matrix containing a tungsten-specific matrix, to remove ¹⁸⁸ W emissions. Can be included. Alternatively, an adsorbent capable of absorbing tungsten may be incorporated into the generator column below the zirconium tungstate matrix, and the eluant may pass through the adsorbent after passing through the tungstate matrix. Another advantage of utilizing a tungsten-absorbing adsorbent is to minimize the loss of matrix particulates and reduce the amount of eluent containing contaminant particles that must be eliminated.

The ¹⁸⁸ W / ¹⁸⁸ Re generator of the present invention is extremely compact and requires a small generator matrix. ^{Since 188} W can be produced by neutron capture with a specific activity of about 1 Curie (Ci) / g or more, using the method of the present invention, the capacity is only 5 ml.
A small (Curie-sized) generator column can be constructed.

The above description will become more apparent in connection with the experimental examples described below. However, these experimental examples are merely for explanation, and do not limit the concept of the invention.

EXAMPLES Example I Preparation of an Irradiation Target Soluble with Aluminum Perrhenate Procedure No. 1 0.1 ml of concentrated nitric acid was carefully pipetted into a beaker containing 50 mg of rhenium metal. After 2-3 minutes, 0.1 ml of 1: 1 v / v concentrated nitric acid: water solution was added to the reaction mixture and the mixture was allowed to react for 20 minutes at room temperature. To this mixture was added 0.5 ml of water, followed by 0.2 ml of a 0.447 M aluminum chloride solution. Mix for 12 hours
Heated to 95 ° C and dried. 1 ml of water was added to the beaker to dissolve residual solids and the solution was filtered. The filtrate
Heat to dry at 95 ° C. for 12 hours to obtain white solid aluminum perrhenate. Table I shows the elemental analysis of Al and Re.

Procedure No. 2 To 50 mg of rhenium metal was carefully added 0.5 ml of a 30% H ₂ O ₂ solution. After 10 minutes, 0.5 ml of water was added to the mixture and the mixture was heated to 95 ° C. for 30 minutes. 0.2m for mixture
l of 0.447M aluminum chloride solution was added and the mixture was dried by heating at 95 ° C for 12 hours. 1 ml of water was added to dissolve the solid and the solution was filtered. The filtrate was dried by heating at 95 ° C. for 12 hours to obtain a white solid aluminum perrhenate.

Procedure No. 3 0.1 ml of concentrated nitric acid was carefully pipetted into 50 mg of rhenium metal. After 2-3 minutes, 0.1 ml of 1: 1 v / v concentrated nitric acid:
An aqueous solution was added to the reaction mixture and the mixture was allowed to react at room temperature for 20 minutes. 0.1 ml of ammonium hydroxide (conc.) Was added to the reaction mixture, followed by another 0.5 ml of water. The mixture was heated to 95 ° C. until all solids were dissolved, and to the mixture was added 0.2 ml of a 0.447 M aluminum chloride solution. The solution was dried by heating at 95 ° C. for 12 hours. Then 1 ml of water was added to dissolve the solid and the solution was filtered. Finally, the filtrate was dried by heating at 95 ° C. for 12 hours to obtain a white solid aluminum perrhenate.

Procedure No. 4 The procedure described in Procedure No. 1 was followed. However, instead of natural metal rhenium in Procedure No. 1, 50 mg of concentrated Re-185 metal rhenium (95% Re-185, Isotec, Inc., Dayton, Ohio)
It was used.

Procedure No.5 The procedure described in Procedure No.2 was followed. However, instead of the naturally occurring rhenium and aluminum chloride solutions in Procedure No. 2, 75 mg of concentrated rhenium metal (95% Re-185, Isotec, Inc.,
Dayton, Ohio) and 0.3 ml of a 0.477 M aluminum chloride solution were used.

Procedure No. 6 The procedure described in Procedure No. 3 was followed. However, instead of the naturally occurring metal rhenium in Procedure No. 3, 50 mg of concentrated Re-185
Metallic rhenium (95% Re-185, Isotec, Inc., Dayton, Ohi
o) was used.

The products of Procedure Nos. 1 to 6 were dissolved in 2 ml of water and diluted 1: 200 and analyzed for rhenium and aluminum content. As a result, the amounts of rhenium and It was found to contain aluminum.

Example II Irradiation of a Soluble Aluminum Perrhenate Target A 0.24 mg sample of aluminum perrhenate obtained by procedures 4, 5 and 6 of Example I was sealed under vacuum in a flame-sealed quartz irradiation bottle. Irradiated bottles at University
of Missouri Research Reactor (Columbia, Missou
ri) at 3 × 10 ¹⁴ neutrons / cm ² / s for 12-14 days
Irradiated in ec flux. The irradiation bottle was opened and the irradiated aluminum perrhenate was dissolved in 0.5 ml of water.
The average activity of recovery was found 90% or more, activity is (reverse phase according to HPLC) ¹⁸⁶ ReO ₄ ^- was identified as a ¹⁸⁶ Re take the form (by germanium-lithium analyzer).

Example III Preparation of Sodium Tungstate Target 0.29 g of ¹⁸⁶ WO ₃ (96% ¹⁸⁶ W, Oak Ridg in a 5 ml beaker)
e National Laboratory, Oak Ridge, Tennessee).
5 ml of 5N NaOH solution are added and the mixture is heated to ¹⁸⁶ WO ₃
Was dissolved. When dissolution is complete, the mixture is allowed to cool to room temperature and the pH is adjusted to 9 by adding 5N HCl and 1N HCl.
Was adjusted to The solution was dried by heating to obtain 0.292 g of white solid sodium tungstate.

Example IV Irradiation of a Soluble Sodium Tungsten Target A 20 mg sample of sodium tungsten (W-186) prepared by the procedure of Example III was flamed under vacuum.
It was sealed in a sealed quartz irradiation bottle. Irradiate bottles for 7 days at the University of Missouri Research Reacto
Irradiation with r (Columbia, Missouri) in a flux of 3 × 10 ¹⁴ neutrons / cm ² / sec. ¹⁸⁷ W and ²⁴ Na decays from the irradiated material. The irradiation bottle was then opened and the irradiated sodium tungstate dissolved in 1 ml of water. This solution
Filtered with a 0.2 μm filter. The activity recovery was measured to be 95% or more.

Example V Preparation of a Zirconium Tungstate Generator 40 mg of irradiated sodium tungstate prepared as described in Example IV was dissolved in 2 ml of water and filtered through a 0.2 μm filter. A solution of 200 mg of naturally occurring Na ₂ WO ₄ in 4 ml of H ₂ O was added to the filtrate to promote precipitation of the insoluble tungstate. Then 312 mg of ZrO in 6 ml of HCl solution
The tungstate solution was added dropwise to a pH 1 acidic zirconyl solution containing (NO ₃ ) ₂ . The pH of the resulting zirconium tungstate mixture was 6.0. The mixture was filtered and washed with 50 ml of water. The gel precipitation yield (% of ¹⁸⁸ W originally present in the gel) was greater than 95%. The filtered gel was air dried overnight, loaded onto a known generator column, and eluted with saline. The elution yield of the zirconyl tungstate generator was 66%.

While the invention has been described above with reference to a preferred embodiment, it will be apparent to those skilled in the art that various modifications can be made. All such modifications are intended to be included within the scope of the following claims, unless prevented by known technology.

Continuing the front page (72) Inventor Sue, Hoo Minh United States, 98125 Washington, Seattle, North East 100th Street 3254 (72) Inventor Erhard, Gary Jay United States, 65203 Missouri, Columbia, Country Hill Road 4328 ( 56) References International Journal of Applied Radiation and Isotopes 1969, Vol. 20 pp. 467− 470 (58) Field surveyed (Int.Cl. ⁶ , DB name) G21G 4/08 G21G 1/06 A61K 49/02

Claims (12)

(57) [Claims] 1. A method for the preparation of a rhenium-186 or rhenium-188 radionuclide for treatment or diagnosis, wherein the aqueous irradiation is selected from the group consisting of aluminum perrhenate, lithium perrhenate and magnesium perrhenate. A method comprising: irradiating a target to obtain a radionuclide or a parent isotope of the radionuclide; and dissolving the irradiated target in an aqueous solution. 2. The method according to claim 1, wherein the radionuclide is ¹⁸⁶ Re, and the irradiation target contains ¹⁸⁵ Re enriched. 3. The method according to claim 2, wherein the irradiation target comprises enriched ⁷ Li in the form of lithium perrhenate. 4. The method of claim 1, wherein said radionuclide is ¹⁸⁸ Re and said irradiation target comprises ¹⁸⁷ Re enriched. 5. A method of irradiating a water-soluble irradiation target selected from the group consisting of aluminum perrhenate, lithium perrhenate and magnesium perrhenate, and dissolving the irradiated target in an aqueous solution. 186 manufacturing method. 6. The method according to claim 5, wherein said irradiation target is concentrated in rhenium-185. 7. The method according to claim 6, wherein said irradiation target is aluminum perrhenate. 8. A step of irradiating a water-soluble irradiation target selected from the group consisting of sodium tungstate and lithium tungstate, a step of reacting the irradiated target with an aqueous solution of zirconium to obtain an insoluble zirconium tungstate gel, A method for producing rhenium-188, comprising the steps of filling a zirconium tungstate gel in an elution vessel and recovering rhenium-188 by eluting the gel. 9. The method according to claim 8, wherein said irradiation target is sodium tungstate. 10. A method for producing a rhenium-188 radionuclide generator, comprising: irradiating a water-soluble irradiation target selected from the group consisting of sodium tungstate and lithium tungstate. Reacting the irradiated target with an aqueous solution of zirconium to obtain an insoluble zirconium tungstate gel, and filling the elution vessel with the zirconium tungstate gel to obtain a rhenium-188 radionuclide generator. 11. The method according to claim 10, wherein said irradiation target is sodium tungstate. 12. A rhenium compound selected from the group consisting of aluminum perrhenate, lithium perrhenate, and magnesium perrhenate and for use in therapy or diagnosis.
A water-soluble irradiation target used in a method for producing a 186 or rhenium-188 radionuclide, wherein the method comprises the following steps: irradiating the water-soluble irradiation target with a radionuclide or a parent isotope of the radionuclide. A water-soluble irradiation target, comprising: obtaining a body; and dissolving the irradiated target in an aqueous solution.