RT Journal Article
SR Electronic
T1 The Cyclotron Production of Actinium-225 in CYCIAE-100
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1459
OP 1459
VO 62
IS supplement 1
A1 Junyi Chen
A1 Zhibo Liu
YR 2021
UL http://jnm.snmjournals.org/content/62/supplement_1/1459.abstract
AB 1459Introduction: Actinium-225 (t1/2=10.0 d, 100% α) is considered as the next generation nuclide for Targeted radionuclide therapy (TRT). Ac-225 emits 4 α-particles and 2 β-particles in a row, which is considered as one of the most potent radionuclides against cancer. In general, ED50 of Ac-225 is 3-order lower than that of Lu-177. However, the limited supply of Ac-225 has hampered its research and further clinical application. In general, Actinium-225 is generated from Uranium-233 decay and the production of Ac-225 is <2 Ci per year. The other possible strategy to produce Ac-225 is from accelerator through 232Th(p, x)225Ac reaction on high-energy accelerator. In this study, we used 100 MeV protons to irradiate natural ThO2 target with CYCIAE-100 (100 MeV H-, 500 μA) and produced Ac-225. To isolate Ac-225 from other side products, we optimized the purification process, which consists of cation-exchange and solid-phase extraction with AG50W-X8 resin, DGA resin, and TRU resin to avoid liquid-liquid extraction. At last, high radiochemical purity Ac-225 product was obtained with ideal recovery rate. Methods: ThO2 powder was prepared as the target materials from analytically pure Th(NO3)4. The ThO2 powder was put into a niobium-made powder target and irradiated with about 2 μA 100 MeV proton (CYCIAE-100) and cooled with rapid airflow. 10 days cooling after end of beam (EOB), the irradiated ThO2 powder was dissolved in hot HNO3- HF and reconstituted in citric acid. AG50W-X8 cation exchanger resin, DGA resin and TRU resin were applied to the isolation process with solid-phase extraction. The qualitative and quantitative analysis of nuclear was done with HPGe Gamma-ray spectroscopy detector. Results: 619 µCi (EOB) of Ac-225 were produced with 7.18±1.08 mb experiment cross-sections. The abundance of Ac-225 of the irradiated ThO2 powder is still less than 3%, leading to the challenge for Ac-225 isolation. The optimized the purification process, which consists of cation-exchange and solid-phase extraction with AG50W-X8 resin, DGA resin, and TRU resin without liquid-liquid extraction, made the successful isolation for over 200 µCi of Ac-225 with radiochemical purity > 99.5%, recovery rate ~95% and < 4 hours time-cost. Conclusions: By using a 100 MeV cyclotron, we have successfully performed a pilot study of production and isolation of Ac-225, demonstrating the possibility of producing Ac-225 with the cyclotron in China.