PURPOSE: Radium was the foundation of brachytherapy in the early decades of the 20th century. Despite being a most precious and perilous substance, it was mislaid with surprising frequency. This essay explores how it was lost, the efforts taken to recover it, and measures instituted to prevent mishandling.

METHODS AND MATERIALS: Review of contemporary literature, government publications, archives, and lay press.

RESULTS: Radium is a particularly dangerous substance because of its long half-life, its gaseous daughter (radon), and the high-energy emissions of its decay products. Despite the hazard, it was unregulated for most of the century. Any physician could obtain and administer it, and protocols for safe handling were generally lacking. Change came with appreciation of the danger, regulation, mandated training, and the institution of a culture of accountability. Unfortunately, careless management of medical radionuclides remains a global hazard.

CONCLUSION: Responsible stewardship of radioactive material was not a high priority, for practitioners or the federal government, for much of the 20th century. As a result, large quantities of radium had gone astray, possibly subjecting the general public to continued radiation exposure. Lessons from the radium era remain relevant, as medical radionuclides are still mishandled.