Non-invasive imaging of radiocesium dynamics in a living animal using a positron-emitting 127Cs tracer

Visualizing the dynamics of cesium (Cs) is desirable to understand the impact of radiocesium when accidentally ingested or inhaled by humans. However, visualization of radiocesium in vivo is currently limited to plants. Herein, we describe a method for the production and purification of 127 Cs and its use in visualizing Cs dynamics in a living animal. The positron-emitting nuclide 127 Cs was produced using the 127 I (α, 4n) 127 Cs reaction, which was induced by irradiation of sodium iodide with a 4 He 2+ beam from a cyclotron. We excluded sodium ions by using a material that specifically adsorbs Cs as a purification column and successfully eluted 127 Cs by flowing a solution of ammonium sulfate into the column. We injected the purified 127 Cs tracer solution into living rats and the dynamics of Cs were visualized using positron emission tomography; the distributional images showed the same tendency as the results of previous studies using disruptive methods. Thus, this method is useful for the non-invasive investigation of radiocesium in a living animal.