Carbon traces changes — Fallout from nuclear bomb tests is allowing University of California at Los Angeles scientists to develop a new method for tracing vital chemical and physical changes in the human body. Radioactive carbon increased by “dirty” H-bombs of 1961–62 opens up a way for measuring the metabolic turnover rate of tissue in the brain, heart, liver and blood stream, without endangering the human subject…. The new technique may give life scientists a new and simple way of studying the formation and decay of tissues and cells. — Science News Letter, February 20, 1965
UPDATE
Doctors routinely use radioactive atoms to check for cancer, heart disease and other illnesses. The best-known example is positron emission tomography, or the PET scan. Patients swallow a tracer — a radioactive carbon, nitrogen, oxygen or fluorine fastened to a carrier molecule — or have it injected. A scanner tracks this tiny amount of radioactive material through the body, creating images that reveal how organs and tissues are functioning.