Cyclotron production of Pd using a liquid target.

Introduction: In this work, we present the first feasibility study on the production of the medically important radionuclide Pd via the Rh(p,n)Pd reaction by cyclotron irradiation of a liquid target. Using a liquid target removes the time consuming and complex dissolution process of rhodium post-irradiation due to its chemically inactive nature and thereby will improve the accessibility of this radioisotope.

Methods: Liquid targets made from Rh(NO)·×HO salt dissolved in de-ionized water were irradiated using a 12 MeV beam at the TR13 cyclotron at TRIUMF, Vancouver.

Results: A maximum EOB activity of 1.03 ± 0.05 MBq was achieved with the tested conditions, sufficient for basic radiochemistry studies. An effective separation method using anion exchange chromatography is reported using 1 M HNO as an eluent for rhodium (90.1 ± 2.1 % recovery) and a 1:1 mixture of 0.5 M NH + NHCl palladium eluent (103.8 ± 2.3 % recovery). The solution showed good in-target pressure stability. However, the production efficiency decreased significantly with higher solution concentrations and irradiation lengths which puts into question the scaling potential of this method.

Conclusion: This proof-of-concept study has demonstrated the potential for using liquid targets as complementary production method of Pd for research purposes. The liquid target route faces several scaling challenges but can nonetheless improve the availability of Pd and consequently aid in widening its utility for radiopharmaceuticals.