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The newest radioisotope for brachytherapy treatment of prostate cancer is ¹³¹Cs (t_1/2 = 9.69 d, 100% EC). Generated via electron capture decay of ¹³¹Ba (t_1/2 = 11.6 d, 100% EC), ¹³¹Cs has been used in brachytherapy for prostate cancer since 2004. The ¹³¹Ba parent is produced through neutron capture of enriched ¹³⁰Ba in a nuclear reactor. For large-scale production of ¹³¹Ba, an accurate knowledge of production and burnup cross sections of ¹³¹Ba are essential. Here, we report two group cross sections (thermal and resonance integrals) for ¹³⁰Ba and ¹³¹Ba and a new measure of the half-life of ¹³¹Ba. Targets consistingmore » of milligram quantities of enriched 130Ba (~35%) were irradiated in Oak Ridge National Laboratory's High Flux Isotope Reactor at thermal and resonance neutron fluxes of (1.9–2.1) × 10¹⁵ and (5.8–7.0) × 10¹³ neutrons·cm^-2 s^-1, respectively, for durations ranging from 3 to 26 days. In addition, cadmium covered samples of ¹³⁰Ba were irradiated for 1 hour at 12.6% full reactor power (10.7 MW). The yield of ¹³¹Ba approaches a saturation value of ~60 GBq (~1.6 Ci) per mg of ¹³⁰Ba for 20 days irradiation at a thermal neutron flux of 1.8 × 10¹⁵ n·s^-1·cm^-2, with a thermal/epithermal ratio of ~30. Under the above experimental conditions, the two group cross sections of ¹³⁰Ba are 6.9 ± 0.5 b (thermal, σ⁰) and 173 ± 7 b (resonance, I⁰). These values represent the sum of cross sections to metastable and ground states of ¹³¹Ba. For ¹³¹Ba, the empirically measured thermal cross section is 200 ± 50 b assuming an I⁰/σ⁰ of 10. This cross section is reported for the first time. Further, the half-life of ¹³¹Ba was remeasured to be 11.657 ± 0.008 d. Lastly, this study also resulted in the co-production of ¹³³Ba (t_1/2 = 10.52 y, 100% EC). The experimental yield of ¹³³Ba is ~370 MBq (~10 mCi) per mg of ¹³²Ba (thin target) for one cycle irradiation in the High Flux Isotope Reactor, and measured two-group ¹³²Ba cross sections are 7.2 ± 0.2 b and 39.9 ± 1.3 b. These values also represent the sum of cross sections to metastable and ground states of ¹³³Ba.« less

Gadolinium vanadate nanoparticles (NPs) doped with europium, in concentrations between 5–40%, were synthesized via an aqueous route to prove their multimodal imaging functionalities and their performance as radionuclide carriers for targeted alpha therapy. Core–shell Gd_0.8Eu_0.2VO₄ NPs were doped with the α-emitting actinium-225 to assess the in vitro retention of ²²⁵Ac and its decay daughters; francium-221 and bismuth-213. Gd_0.8Eu_0.2VO₄ core–shell NPs were obtained using a precipitation synthesis route having a tetragonal system, a spherical morphology, and a uniform particle size distribution. Gd_0.8Eu_0.2VO₄ core–shell NPs displayed the characteristic intense emission at 618 nm (red) and paramagnetic behavior of Eu and Gd cations,more » respectively. Partial retention of radionuclides was obtained with Gd_0.8Eu_0.2VO₄ core NPs, while deposition of two nonradioactive Gd_0.8Eu_0.2VO₄ shells significantly decreased the leakage of both ²²⁵Ac and ²²¹Fr. As a result, the luminescence and magnetic functionalities as well as radionuclide retention capabilities of Gd_0.8Eu_0.2VO₄ core–shell NPs demonstrate their potential for biomedical applications.« less

Lanthanide phosphate nanomaterials are appealing as multifunctional platforms for biomedical applications because of their low toxicity, radiation resistance, and unique luminescence and magnetic properties. Lanthanide phosphate nanoparticles (NPs) radiolabeled with ¹⁵⁶Eu were synthesized by an aqueous route using sodium tripolyphosphate as a phosphate source and complexing agent. GdPO₄ was used as a host matrix, while synthetic concentrations of Ce³⁺/Tb³⁺ and Eu³⁺ were varied between 5–40% and 10–30%, respectively, and yielded spherical NPs with hexagonal crystal system and particle size < 5 nm. Luminescence emission and magnetic susceptibility were influenced by lanthanide concentrations where characteristic ⁵D₀-⁷F_J and ⁵D₄-⁷F_J transitions were observedmore » for Eu³⁺- and Tb³⁺-doped NPs, respectively. Chemical yield of > 90% was achieved for GdPO₄ and Gd_0.6Ce_0.3Tb_0.1PO₄ NPs intrinsically radiolabeled with ¹⁵⁶Eu. Lastly, in vitro retention of ¹⁵⁶Eu within LnPO₄ NPs was > 97% over 3 weeks. Intrinsically radiolabeled LnPO₄ NPs have the potential to combine the luminescence and magnetic properties of Ln³⁺ ions with lanthanide radioisotopes for biomedical and environmental applications.« less

A new method has been developed for the isolation of ^223,224,225Ra, in high yield and purity, from a proton irradiated ²³²Th matrix. We report an all-aqueous process using multiple solid-supported adsorption steps including a citrate chelation method developed to remove >99.9% of the barium contaminants by activity from the final radium product. Moreover, we developed a procedure involving the use of three columns in succession, and the separation of ^223,224,225Ra from the thorium matrix was obtained with an overall recovery yield of 91 ± 3%, average radiochemical purity of 99.9%, and production yields that correspond to physical yields based onmore » previously measured excitation functions.« less

A method for preparation of Pb-212 and Pb-203 labeled chelator-modified peptide-based radiopharmaceuticals for cancer imaging and radionuclide therapy has been developed and adapted for automated clinical production. Pre-concentration and isolation of radioactive Pb2+ from interfering metals in dilute hydrochloric acid was optimized using a commercially-available Pb-specific chromatography resin packed in disposable plastic columns. The pre-concentrated radioactive Pb2+ is eluted in NaOAc buffer directly to the reaction vessel containing chelator-modified peptides. Radiolabeling was found to proceed efficiently at 85 °C (45 min; pH 5.5). The specific activity of radiolabeled conjugates was optimized by separation of radiolabeled conjugates from unlabeled peptide viamore » HPLC. Preservation of bioactivity was confirmed by in vivo biodistribution of Pb-203 and Pb-212 labeled peptides in melanoma-tumor-bearing mice. The approach has been found to be robustly adaptable to automation and a cassette-based fluid-handling system (Modular Lab Pharm Tracer) has been customized for clinical radiopharmaceutical production. Our findings demonstrate that the Pb-203/Pb-212 combination is a promising elementally-matched radionuclide pair for image-guided radionuclide therapy for melanoma, neuroendocrine tumors, and potentially other cancers.« less