Evaluation of 72Se/72As generator and production of 72Se for supplying 72As as a potential PET imaging radionuclide

Radioarsenic: A promising theragnostic candidate for nuclear medicine

Molecular imaging is a non-invasive process that enables the visualization, characterization, and quantitation of biological processes at the molecular and cellular level. With the emergence of theragnostic agents to diagnose and treat disease for personalized medicine there is a growing need for matched pairs of isotopes. Matched pairs offer the unique opportunity to obtain patient specific information from SPECT or PET diagnostic studies to quantitate in vivo function or receptor density to inform and tailor therapeutic treatment. There are several isotopes of arsenic that have emissions suitable for either or both diagnostic imaging and radiotherapy. Their half-lives are long enough to pair them with peptides and antibodies which take longer to reach maximum uptake to facilitate improved patient pharmacokinetics and dosimetry then can be obtained with shorter lived radionuclides. Arsenic-72 even offers availability from a generator that can be shipped to remote sites and thus enhances availability. Arsenic has a long history as a diagnostic agent, but until recently has suffered from limited availability, lack of suitable chelators, and concerns about toxicity have inhibited its use in nuclear medicine. However, new production methods and novel chelators are coming online and the use of radioarsenic in the pico and nanomolar scale is well below the limits associated with toxicity. This manuscript will review the production routes, separation chemistry, radiolabeling techniques and in vitro/in vivo studies of three medically relevant isotopes of arsenic (arsenic-74, arsenic-72, and arsenic-77).

Evaluation of the nuclear reaction cross sections via proton induced reactions on 72Ge and 76Se to produce 72As: A potential entrant for the theranostic pairs

Theranostic applications of radiopharmaceuticals have revolutionized present era specially, dealing with cancer diseases. Increase in the uses of radionuclides in nuclear medicine has resulted in the demands of optimized new radionuclides to be produced focussing on the economy, simplicity and maximum yield. Two radionuclides of arsenic offer a well agreed theranostic systems namely ⁷⁷As and ⁷²As. Some arsenic radionuclides are capable of positron-emission, with range of hour to weeks half-lives and have potential to be used for nuclear medicine. Present work will elucidate the production of ⁷²As on Germanium and Selenium via proton induced nuclear reactions. The experimental results obtained by several nuclear reactions were analyzed. The results of nuclear model codes namely ALICE-IPPE, EMPIRE-3.2.3 and TALYS-1.9 are compared with the experimental cross sections to generate recommended cross section data. Recommended excitation functions are used to compute the thick target yields (TTY) of ⁷²As. Assessment of radionuclidic impurities are also studied and comparison of several radionuclidic impurities is done. To produce ⁷²As,⁷²Ge (p, n)⁷²As, ⁷³Ge (p, 2n)⁷²As, ⁷⁴Ge (p, 3n)⁷²As and ⁷⁶Se (p, x)⁷²As reactions in different energy ranges are discussed. We have identified ⁷²Ge (p, n)⁷²As reaction; gives pre-eminent yield with least impurities mark it as feasible entrant to be applied in Positron Emission Tomography (PET) and theranostic applications.