Four terbium isotopes 149,152,155,161Tb emitting various types of radiation can be used for both diagnostics and therapy. 152Tb emits positrons and is ideal for PET. 155Tb is considered a promising ...Auger emitter and a diagnostic pair for other terbium therapeutic isotopes. Several methods for the production of 155Tb using charged particle accelerators have been proposed, but they all have significant limitations. The restricted availability of this isotope hinders its medical applications. We have proposed a new method for production of 155Tb, irradiating enriched 155Gd by alpha particles. The possibility of simultaneous production of two isotopes of terbium, 152,155Tb, was also studied for more efficient cyclotron beam use.
Irradiation of 155Gd enriched targets and 155Gd / 151Eu tandem target with alpha-particles with an energy of 54 MeV was carried out at the U-150 cyclotron at the NRC “Kurchatov Institute”. The cross sections of nuclear reactions on enr-155Gd were measured by the stack foil technique, detecting the gamma-radiation of the activation products. The separation of rare earth elements was performed by extraction chromatography with the LN Resin. 155Tb was produced via 155Dy decay.
The cross sections for the 155,156Tb and 155,157Dy production were measured by the irradiation of a gadolinium target enriched with the 155Gd isotope with alpha-particles in an energy range of 54 → 33 MeV. The yield of 155Dy on a thick target at 54 MeV was 130 MBq/μAh, which makes it possible to obtain 1 GBq of 155Tb in 11 h-irradiation with 20 μA beam current. The possibility of simultaneous production of 152,155Tb by irradiation of 155Gd and 151Eu tandem target with medium-energy alpha-particles is implemented. Optimal irradiation energy ranges of alpha -particles as 54 → 42 MeV for 155Tb and 42 → 34 MeV for 152Tb were suggested. Product activity and radionuclidic purity were calculated.
New nuclear data relevant to the production of 155Tb were obtained. The proposed tandem target approach allows for increasing the availability of medical radioisotopes 152,155Tb.
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Separation technique of rhenium radioisotopes from a deuteron-irradiated tungsten target of natural isotopic composition has been developed. The irradiated tungsten powder was dissolved in a mixture ...of H
2
O
2
and NaOH, the solution was passed through a column filled with an extraction chromatographic sorbent TEVA Resin. Rhenium was eluted with 4 M nitric acid. The separation procedure takes approximately 3 h, the radiochemical yield of rhenium is more than 97%.
155Tb (T1/2 = 5.32 d) is considered both as a promising Auger electron emitter and as a diagnostic pair for other therapeutic terbium radionuclides. Despite several methods for its production ...proposed, it remains scarcely available. Most of the methods using low-energy protons and deuterons beams result in a high content of radionuclidic impurities. High purity 155Tb can be obtained using high-energy proton beams combined with online mass separation of products, but the method remains inaccessible to most potential consumers. We have proposed an indirect method for the production of 155Tb via formation of 155Dy (T1/2 = 9.9 h), which can be implemented using medium energy alpha particles beam.
Gadolinium oxide targets of natural isotopic composition were irradiated by 60 MeV alpha particles beam on a U-150 cyclotron of the National Research Center “Kurchatov Institute”. The cross sections of nuclear reactions were measured by the stack foil technique, detecting the gamma radiation of the activation products. Gd, Tb, and Dy were separated by extraction chromatography using the LN Resin sorbent in nitric media. The isolated dysprosium fraction was stored for a day, and the formed 155Tb was isolated by the same method.
The cross sections for the formation of 159Gd, 153-156Tb, and 155,157Dy under irradiation by alpha particles of a gadolinium target of natural isotopic composition in the energy range 20–60 MeV have been measured. The 155Dy yield on a thick target at 60 MeV was 35 MBq/μAh, which makes it possible to obtain 1 GBq 155Tb as a result of 12-hour irradiation with a beam current of 50 μA. Extraction chromatography on LN Resin sorbent in nitric enabled quick and efficient separation of Gd, Tb, and Dy. The radiochemical yield of Dy was 95%, for Tb > 95%. The main radionuclidic impurity is 153Tb (T1/2 = 2.34 d; <5.4% of 155Tb activity).
The developed method allows the production of therapeutic amounts of 155Tb with acceptable radionuclidic purity without the need for isotopically enriched materials.
The amount of 155Tb is sufficient for its use in Auger therapy, as well as for preclinical studies of the suitability of SPECT preparations in laboratory animals. Nevertheless, to obtain higher activities, a longer irradiation time and a higher projectile current are proposed.
The 153Tb radionuclide present in the final preparation has a shorter half-life than the target radionuclide, and its hard γ-lines have a probability of emission of less than 1%, from which it can be concluded that the negative effect will not be significant. However, a product of this purity and type of contamination requires additional testing for toxicity in living organisms. The final sample also includes a certain amount of 157Tb (T1/2 = 71 a, the only γ-line 54.5 keV Iγ = 0.0084%), which will complicate the labeling conditions. Thus, more research is needed in the labeling area.
It should be noted that the use of gadolinium enriched in the 155Gd or 156Gd nuclide as a target will help not only reduce the amount of impurities but also increase the yield of 155Tb.
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Two rhenium isotopes (
186
Re and
188
Re) are of interest for nuclear medicine. The multiplicity of oxidation states and varying coordination chemistry of rhenium provide opportunities for the ...synthesis of various bioconjugates, including those based on nanosized carriers (liposomes, dendrimers, and inorganic nanoparticles). This review analyzes nuclear reactions that lead to the formation of rhenium isotopes and methods of their isolation from targets, as well as different variants of the application of rhenium in nuclear medicine.
A laboratory setup has been developed for the isolation of rhenium radioisotopes from an irradiated tungsten target using extraction chromatography. The operation of the setup was tested using a ...target made of metallic tungsten of natural isotopic composition, irradiated with deuterons at the U-150 cyclotron of the Kurchatov Institute. The possibility of complete separation of rhenium from large amounts (hundreds of milligrams) of tungsten has been shown. During separation, rhenium is concentrated in a minimum volume (5 mL) of the final solution, providing a high specific activity required for further experiments to create a radiopharmaceutical.
Irradiation of 186W targets by 3He particles was carried out. For the first time the cross sections for the reactions of production of 183, 184, 186, 188Re, 183, 185Os, 187W were measured by the ...stack foil technique in the 3He energy range of 15–45 MeV. The results were compared to the data from the TENDL-2019 library. Using the experimental excitation functions, the thick target yields of medically relevant rhenium radioisotopes were calculated.
•The production cross sections of radioisotopes from 3He-particle induced reactions on 186W target are measured.•The results are compared with data from the TENDL-2019 library.•The suitability of the method for the production of medical radionuclides 186Re and 188Re is evaluated.
Tb (T
= 5.32 d) is considered both as a promising Auger electron emitter and as a diagnostic pair for other therapeutic terbium radionuclides. Despite several methods for its production proposed, it ...remains scarcely available. Most of the methods using low-energy protons and deuterons beams result in a high content of radionuclidic impurities. High purity
Tb can be obtained using high-energy proton beams combined with online mass separation of products, but the method remains inaccessible to most potential consumers. We have proposed an indirect method for the production of
Tb via formation of
Dy (T
= 9.9 h), which can be implemented using medium energy alpha particles beam.
Gadolinium oxide targets of natural isotopic composition were irradiated by 60 MeV alpha particles beam on a U-150 cyclotron of the National Research Center "Kurchatov Institute". The cross sections of nuclear reactions were measured by the stack foil technique, detecting the gamma radiation of the activation products. Gd, Tb, and Dy were separated by extraction chromatography using the LN Resin sorbent in nitric media. The isolated dysprosium fraction was stored for a day, and the formed
Tb was isolated by the same method.
The cross sections for the formation of
Gd,
Tb, and
Dy under irradiation by alpha particles of a gadolinium target of natural isotopic composition in the energy range 20-60 MeV have been measured. The
Dy yield on a thick target at 60 MeV was 35 MBq/μAh, which makes it possible to obtain 1 GBq
Tb as a result of 12-hour irradiation with a beam current of 50 μA. Extraction chromatography on LN Resin sorbent in nitric enabled quick and efficient separation of Gd, Tb, and Dy. The radiochemical yield of Dy was 95%, for Tb > 95%. The main radionuclidic impurity is
Tb (T
= 2.34 d; <5.4% of
Tb activity).
The developed method allows the production of therapeutic amounts of
Tb with acceptable radionuclidic purity without the need for isotopically enriched materials. The amount of
Tb is sufficient for its use in Auger therapy, as well as for preclinical studies of the suitability of SPECT preparations in laboratory animals. Nevertheless, to obtain higher activities, a longer irradiation time and a higher projectile current are proposed. The
Tb radionuclide present in the final preparation has a shorter half-life than the target radionuclide, and its hard γ-lines have a probability of emission of less than 1%, from which it can be concluded that the negative effect will not be significant. However, a product of this purity and type of contamination requires additional testing for toxicity in living organisms. The final sample also includes a certain amount of
Tb (T
= 71 a, the only γ-line 54.5 keV Iγ = 0.0084%), which will complicate the labeling conditions. Thus, more research is needed in the labeling area. It should be noted that the use of gadolinium enriched in the
Gd or
Gd nuclide as a target will help not only reduce the amount of impurities but also increase the yield of
Tb.
Four terbium isotopes
Tb emitting various types of radiation can be used for both diagnostics and therapy.
Tb emits positrons and is ideal for PET.
Tb is considered a promising Auger emitter and a ...diagnostic pair for other terbium therapeutic isotopes. Several methods for the production of
Tb using charged particle accelerators have been proposed, but they all have significant limitations. The restricted availability of this isotope hinders its medical applications. We have proposed a new method for production of
Tb, irradiating enriched
Gd by alpha particles. The possibility of simultaneous production of two isotopes of terbium,
Tb, was also studied for more efficient cyclotron beam use.
Irradiation of
Gd enriched targets and
Gd /
Eu tandem target with alpha-particles with an energy of 54 MeV was carried out at the U-150 cyclotron at the NRC "Kurchatov Institute". The cross sections of nuclear reactions on
Gd were measured by the stack foil technique, detecting the gamma-radiation of the activation products. The separation of rare earth elements was performed by extraction chromatography with the LN Resin.
Tb was produced via
Dy decay.
The cross sections for the
Tb and
Dy production were measured by the irradiation of a gadolinium target enriched with the
Gd isotope with alpha-particles in an energy range of 54 → 33 MeV. The yield of
Dy on a thick target at 54 MeV was 130 MBq/μAh, which makes it possible to obtain 1 GBq of
Tb in 11 hour-irradiation with 20 μA beam current. The possibility of simultaneous production of
Tb by irradiation of
Gd and
Eu tandem target with medium-energy alpha-particles is implemented. Optimal irradiation energy ranges of alpha -particles as 54 → 42 MeV for
Tb and 42 → 34 MeV for
Tb were suggested. Product activity and radionuclidic purity were calculated.
Irradiation of
W targets by
He particles was carried out. For the first time the cross sections for the reactions of production of
Re,
Os,
W were measured by the stack foil technique in the
He energy ...range of 15-45 MeV. The results were compared to the data from the TENDL-2019 library. Using the experimental excitation functions, the thick target yields of medically relevant rhenium radioisotopes were calculated.
