Cyclotron production of 225Ac from an electroplated 226Ra target

Purpose We demonstrate cyclotron production of high-quality 225Ac using an electroplated 226Ra target. Methods 226Ra was extracted from legacy Ra sources using a chelating resin. Subsequent ion-exchange purification gave pure 226Ra with a certain amount of carrier Ba. The radium target was prepared by electroplating. We successfully deposited about 37 MBq of 226Ra on a target box. Maximum activation was achieved using 15.6 MeV protons on the target at 20 µA for 5 h. Two functional resins with various concentrations of nitric acid purified 225Ac and recovered 226Ra. Cooling the intermediate 225Ac for 2–3 weeks decayed the major byproduct of 226Ac and increased the radionuclidic purity of 225Ac. Repeating the same separation protocol provided high-quality 225Ac. Results We obtained 225Ac at a yield of about 2.4 MBq at the end of bombardment (EOB), and the subsequent initial purification gave 1.7 MBq of 225Ac with 226Ac/225Ac ratio of < 3% at 4 days from EOB. Additional cooling time coupled with the separation procedure (secondary purification) effectively increased the 225Ac (4n + 1 series) radionuclidic purity up to 99 + %. The recovered 225Ac had a similar identification to commercially available 225Ac originating from a 229Th/225Ac generator. Conclusion This procedure, which involves the 226Ra(p,2n)225Ac reaction and the appropriate purification, has the potential to be a major alternative pathway for 225Ac production because it can be performed in any facility with a compact cyclotron to address the increasing demand for 225Ac.

Cyclotron Production of 225Ac from an electroplated 226Ra Target

Purpose We demonstrate a cyclotron production of high-quality 225Ac using an electroplated 226Ra target. Methods All 226Ra used in this work was extracted from legacy Ra sources using a chelating resin. The subsequent ion-exchange purification gave pure 226Ra with a certain amount of carrier Ba. The radium target was prepared by electroplating. We successfully deposited about 1 mg (mCi) of 226Ra on a target box. Activation was performed by 16.5 MeV protons (on the target) at 20 µA for 5 h as the maximum. Purification of 225Ac as well as 226Ra recovery was performed using two functional resins with various concentrations of nitric acid. Cooling of the intermediate 225Ac for 2–3 weeks decayed the major byproduct of 226Ac and increased the radionuclidic purity of 225Ac. Then the same separation protocol was repeated to provide high-quality 225Ac. Results We obtained 225Ac at a yield of about 2.4 MBq (65 µCi) at EOB, and the subsequent primal purification gave 1.7 MBq (48 µCi) of 225Ac with 226Ac/225Ac ratio of < 4% at 4 d from EOB. Additional cooling time coupled with the repeated separation procedure (secondary purification) effectively increased the 225Ac (4n + 1 series) radionuclidic purity up to 99+%, which showed a similar identification to a commercially available 225Ac originating from a 229Th/225Ac generator. Conclusion The 226Ra(p,2n)225Ac reaction and the appropriate purification procedure has the potential to be a major alternative pathway for 225Ac production and can be performed in any facility with a compact cyclotron to address the increasing demand for 225Ac.

High yield cyclotron production of a novel 133/135La theranostic pair for nuclear medicine

This study reports the high-yield production of a novel 133/135La theranostic pair at a 22 MeV proton beam energy as an attractive alternative to the recently introduced 132/135La pair, demonstrating over an order of magnitude production increase of 133/135La (231 ± 8 MBq 133La and 166 ± 5 MBq 135La at End of Bombardment (EOB)) compared to 11.9 MeV production of 132/135La (0.82 ± 0.06 MBq 132La and 19.0 ± 1.2 MBq 135La) for 500 µA·min irradiations. A new sealed solid cyclotron target is introduced, which is fast to assemble, easy to handle, storable, and contains reusable components. Radiolabeling with macrocyclic chelators DOTA and macropa achieved full incorporation, with respective apparent 133La molar activites of 33 ± 5 GBq/µmol and 30 ± 4 GBq/µmol. PET centers with access to a 22 MeV capable cyclotron could produce clinically-relevant doses of 133/135La, via natBa irradiation, as a standalone theranostic agent for PET imaging and Auger electron therapy. With lower positron energies and less energetic and abundant gamma rays than 68Ga, 44Sc and 132La, 133La appears to be an attractive radiometal candidate for PET applications requiring a higher scanning resolution, a relatively long isotopic half-life, ease of handling, and a low patient dose.

Production of Copper Radionuclides in Compact Medical Cyclotrons using Solid Targets

Background: Over the last several years there has been a growing interest in the use of radiopharmaceuticals labeled with metallic radionuclides, especially isotopes of copper (Cu). Cu has a unique set of radionuclides with potential application not only for diagnostic imaging but also for applications in targeted radionuclide therapy. Objective: To review the methods and routes used for the production of Cu radionuclides in compact medical cyclotrons (Ep<20 MeV) using solid targets. Conclusion: The cyclotron production of Cu radionuclides using solid targets has proven to be very efficient. The large number of compact medical cyclotrons distributed worldwide, and the high target yields in the production of Cu radionuclides achieved at these energies, form a potential network of distribution to satisfy the growing demand for these radionuclides, especially 64Cu.

Cyclotron Production of PET Radiometals in Liquid Targets: Aspects and Prospects

: Present review describes the methodological aspects and prospects of production of Positron Emission Tomography (PET) radiometals in a liquid target using low-medium energy medical cyclotrons. The main objective of this review is to delineate and discuss the critical factors involved in the liquid target production of radiometals including type of salt solution, solution composition, beam energy, beam current, effect of irradiation duration (length of irradiation) and challenges posed by in-target chemistry in relation with irradiation parameters. We also summarize the optimal parameters for production of various radiometals in liquid targets. : Additionally, we discuss the future prospects of PET radiometals production in the liquid targets for academic research and clinical applications. Significant emphasis has been given to the production of 68Ga using liquid targets due to the growing demand for 68Ga labeled PSMA vectors, [68Ga] Ga-DOTATATE, [68Ga]Ga-DOTANOC and some upcoming 68Ga labeled radiopharmaceuticals. Other PET radiometals included in the discussion are 86Y, 63Zn and 89Zr.