Radon seeds, formerly used for vascular and neoplastic tumors, acne, and other dermatological disorders, are rarely, if ever, used today. Because the half-life of radon is 3.83 days, these hollow gold seeds filled with radon gas are usually left in situ permanently.
A case is reported of a woman who had seeds implanted 33 years ago for a vascular lesion. The seeds were removed and found to have minute amounts of residual radiation but not sufficient to cause radiation damage. Since seeds are foreign bodies, removal is recommended if they are easily accessible.
Goldstein N. Radon Seed ImplantsResidual Radioactivity After 33 Years. Arch Dermatol. 1975;111(6):757-759. doi:10.1001/archderm.1975.01630180085013