In 1937, Joseph Hamilton was the first to use radioactive tracers to study circulatory physiology. Using radioactive sodium, Hamilton studied how fast that which we eat enters and traverses the human body.

Hamilton realized that radioisotopes with a short half-life — a property which allows them to be used without medical side effects — were needed. Iodine-131 was the beginning of the Lab’s ongoing role in the discovery and use of radioisotopes.