Experimental approaches for the production of thorium-229

thorium-229, medical radioisotopes, nuclear medicine, actinium-225, cross-sections, thorium-230

Molnar, Mikayla Marie ; Allain ; Jean P

关键词: thorium-229, medical radioisotopes, nuclear medicine, actinium-225, cross-sections, thorium-230;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/106285/MOLNAR-THESIS-2019.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

In the United States, cancer is the second leading cause of death and a major public health problem worldwide. This has influenced researchers in the field of nuclear medicine to develop new and innovative ways for detecting and treating various forms of cancer. Targeted alpha therapy (TAT) is a promising technique for treating metastatic cancer and involves delivering a radionuclide to the cancerous cells in the body, where it decays by releasing high-energy (5-8 MeV) α-particles with high linear energy transfer (LET) over a short (50-100 µm) range and relatively low toxicity to the rest of the body. Actinium-225 is an ideal radioisotope for TAT due to its short half-life (t1/2=9.92 days) and 3 α-emitting decay daughters. Currently, there is not enough 225Ac available to meet expected demand. Therefore, the goal of this research is to produce more of the parent radioisotope, thorium-229 (t1/2=7932 years.) The two methods of production we chose to investigate are 1) the irradiation of a 226Ra target in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) and 2) the fast neutron irradiation of a 230Th target in a particle accelerator. This thesis outlines several experiments completed at ORNL to test the feasibility and preparation procedures for these two production methods. First, we experimentally evaluated the effective neutron cross section of 229Th to be 8.36 ± 0.37 barns, which is more than 3 times lower than the current reported value of 30.8 ± 1.5 barns. Second, we tested methods for preparing uniformly distributed 230Th targets for fast neutron irradiation at Lawrence Berkeley National Laboratory and determined that depositing approximately 25-30 mg of enriched 230Th(NO3)4 onto a high-purity aluminum substrate and sealing the material with Kapton tape to prevent rehydration is the best way to produce this target.