A 212Pb generator based on a 228Th source

A two-compartment 212Pb generator has been constructed and characterized physically and chemically. It is based on transport by airflow of gaseous 220Rn emanating from thin layers of [228Th]barium stearate. 220Rn is collected in a glass bubbler by extraction into an organic solvent and solidified at temperatures below –72°C. Tracer studies show that the decay product 212Pb can be recovered with approximately 70% yield. It is suggested that this generator design could accommodate therapeutic levels of 212Pb/228Th.