11th International Conference on Isotopes
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Browsing 11th International Conference on Isotopes by Subject "cyclotron"
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Item Cross-section Measurement and Thick Target Production of Terbium Radioisotopes by Enriched Gadolinium Targets(2023) wang, yizheng; GUERTIN, Arnaud; NIGRON, Etienne; haddad, ferid; Michel, Nathalie; Sounalet, ThomasIntroduction Short-lived radioisotopes of the terbium (Tb) family show great prospects in theranostics: the 149Tb can be used for alpha therapy, the 152Tb, as a positron emitter, can be applied for the positron emission tomography (PET), the 155Tb can be used for the single photon emission tomography (SPECT) and for Auger therapy, and finally, the 161Tb can be an alternative to 177Lu for β-therapy. Nevertheless, the applications of Terbium are limited at the moment due to its insufficient production and high cost: except for 161Tb, the other radionuclides are produced by nuclear spallation reactions. The use of enriched Gadolinium (Gd) targets can help to increase their availability according to the following production reactions: 152Gd(p,4n)149Tb 1, 152Gd(p,n)152Tb 1, 155Gd(p,n)155Tb 2 and 155Gd(d,2n)155Tb 3. In this work, the 155Tb is taken as a case study, and Gd2O3 enriched in 155Gd is used. Objectives of this work are on the one hand to measure the cross section of the 155Gd(d,2n)155Tb nuclear reaction induced by deuteron, and on the other hand to irradiate enriched Gd2O3 targets for thick target production with deuteron. Description of the Work or Project For the cross section measurement, thin targets (10-20 µm) are required while thicker targets are preferred for production. Therefore, two types of Gd targets with different thicknesses have been developed through two different techniques. Thin targets were manufactured via the electrochemical co-deposition technique. Uniform Ni/Gd2O3 composite targets with a thickness of 10-20 µm containing about 2 mg of enriched Gd were obtained after 35 min of deposition. These targets were irradiated at GIP ARRONAX cyclotron with deuteron beams. Cross sections of 155Tb and other Tb radionuclides (153Tb, 154Tb and 156Tb) were measured from 8 MeV to 30 MeV. These measurements give the first experimental results for the reaction 155Gd(d,x)Tb. From these results, the thick target yield and the purity of 155Tb were estimated. The irradiation parameters for thick target production were also determined from the simulation. Thicker targets were manufactured through the pelletizing technique. A uniform and compact target with a thickness of 390 µm was obtained using 0.6 g of enriched Gd2O3 powder. This target was irradiated by deuteron beams with an incident energy of 15.1 MeV and a beam intensity of 368 nA for 1 h. The production yield of 155Tb was 10.2 MBq/µAh and the purity was 89% after 14 days of decay. These results are consistent with the estimation obtained by the measured cross sections. Conclusions This work shows the possibility of using enriched gadolinium targets to produce terbium radioisotopes via biomedical cyclotrons. Cross sections of deuteron-induced reactions on enriched Gd were measured and a test of thick target production was carried out. As for large batch production, higher intensity and longer irradiation time will be necessary. To this end, specific encapsulation and cooling systems will also be designed and in addition, pure metal Gd targets with better thermal conductivity will be developed.Item The Evolving Landscape of Radioisotopes in Modern Medicine(2023) Schaffer, PaulIntroduction After decades of development, an increasing repertoire of radioisotopes are experiencing rapid growth in demand, both for diagnostic molecular imaging (MI), but also targeted radionuclide therapy (TRT) – two modalities with great potential for the identification and treatment of difficult-to-treat diseases, including micro-metastatic cancers, antibiotic-resistant bacterial infections and viral infections. Clinical MI agents (specifically PET and SPECT radiotracers) were dominated for years by a small group of short-lived, main-group positron-, and metallic single-photon emitting radioisotopes. However, recent advances in technologies in and around solid targets and metal isotope production are now enabling cyclotron centres to produce and distribute many emerging and important radionuclides for clinical use. On the TRT front, recent clinical results demonstrating the efficacy of beta- and alpha-emitting radiopharmaceuticals toward advanced, metastatic disease have triggered a global pursuit for new drugs. Couple this with increasing supply of promising alpha-, beta- and Auger-emitting radionuclides, personalized diagnostic, therapeutic and theranostic medicine is closer to reality now than ever before. Researchers at facilities such as TRIUMF are playing an active and important role in developing and translating new technologies that are paving the way for the discovery and translation of radioisotopes and radiopharmaceuticals that will ultimately enable the paradigm of personalized molecular medicine. Description of the Work or Project Many of the ~1400 medical cyclotrons around the world today operate between 16 and 24 MeV [1], an ideal range for producing, among others, isotopes including 99mTc [2,3], 68Ga [4], 64Cu and 89Zr [5]. Efforts at TRIUMF have led to the development of a solid target transfer and irradiation system, and solid target processing chemistry which has demonstrated a high-yield, automated method for producing GBq-TBq quantities of these isotopes using up to 500 μA of ~13-22 MeV protons. Fully automated dissolution/separation processes along with regulatory filings now allow for cyclotron-produced materials to substitute for other sources used in the clinic today. On the therapeutic isotope front TRIUMF is scaling-up processes to produce 225Ac via the high-energy proton irradiation of 232Th, with the aim of implementing a scalable and routine production operation capable of supporting multiple clinical trials [6]. Targets containing 0.5 mm thick, 11 g thorium foils were irradiated to12,500 μAh with ~450 MeV protons using TRIUMF’s 500 MeV Isotope Production Facility (IPF), producing GBq quantities of 225Ac, 225Ra, 228Th, 212Pb, among a number of other alpha-emitting isotopes of interest [7]. A discussion will include recent experiences with target chemistry automation, product quality control, and Th-spallation waste handling and disposal. Conclusions This presentation will provide a summary update on the development and implementation of several newer technologies toward direct cyclotron-production of various emerging radionuclides across a fleet of 13 to 520 MeV cyclotrons located at TRIUMF and its partner institutions. References [1] Accelerator Knowledge Portal https://nucleus.iaea.org/sites/accelerators/Pages/Cyclotron.aspx [2] Beaver, J.E., Hupf, H.B. (1971). J Nucl Med. 12(11), 739–41. PMID 5113635 [3] Bénard, F. et al. (2014). J.Nucl.Med. 55(6), 1017-22. https://doi.org/10.2967/jnumed.113.133413 [4] Thisgaard, H. et al. (2021). EJNMMI Radiopharmacy and Chemistry. 6:1. https://doi.org/10.1186/s41181-020-00114-9 [5] Oehlke, E. et al. (2015). Nucl. Med. Biol. 42, 842-49. http://dx.doi.org/10.1016/j.nucmedbio.2015.06.005 [6] Robertson, A.K.H. et al. (2020). Inorg. Chem. 59(17), pp. 12156-165. https://doi.org/10.1021/acs.inorgchem.0c01081 [7] Robertson A.K.H., Kunz, P., Hoehr, C., Schaffer, P. (2020). Physics Review C, 102, 044613. https://journals.aps.org/prc/abstract/10.1103/PhysRevC.102.044613