1936: A radioactive isotope is used to treat human disease for the first time, marking the birth of nuclear medicine.

Ernest Lawrence, who would soon win the Nobel Prize in Physics for his invention of the cyclotron, recognized the medical potential of nuclear isotopes. The key, though, was bringing in his brother, John, a hematologist then on the faculty at Yale Medical School, to help research the field's potential, then establish and administer the therapeutic procedures.

Working from their Donner Laboratory (.pdf) in Berkeley, California, John Lawrence began treating a 28-year-old leukemia patient using a radioactive isotope of phosphorus-32 produced in one of his brother's cyclotrons.

The tracers produced by the isotope were used both diagnostically (to evaluate bone marrow metabolism) and therapeutically, and before long the Donner Lab was developing new radioisotopes for radiation therapy, including technetium-99, carbon-14, fluorine-18 and thallium-201. They remain among the most commonly used radionuclides.

Early radiotherapy didn't prove very effective in treating diseases such as leukemia and other forms of cancer. But it did herald the coming of the field of radiology, which represents a maturation of the process begun at the Donner Lab. Modern radiological therapies are very effective in the treatment of some diseases and medical imaging is a critical diagnostic tool.

Which earns John Lawrence the sobriquet father of nuclear medicine.

(Source: Various)