Little was known about iodine metabolism in the mid-1930s, but when Saul Hertz and his chief, J. Howard Means, at the Massachusetts General Hospital (MGH) realized in 1936 that radioiodine could be made and used as a tracer, they arranged with physicists Robley Evans and Arthur Roberts at the Massachusetts Institute of Technology (MIT) to make the short-lived 128I and study its physiology in rabbits. By 1938, they showed that the rabbit's thyroid gland rapidly took up 128I, especially when there was only a little non-radioactive iodine present. There was, however, no hope of using 128I as a treatment because of its brief half-life (25 minutes). In 1939, Joseph Hamilton and Mayo Soley, working with Ernest Lawrence's cyclotron in Berkeley, California, were able to make several radioiodines; one was 130I (12-hour half-life) and another 131I (8-day half-life). They were the first to give these radioiodines to humans to study iodine physiology. The MGH-MIT group also built a cyclotron and by 1940 had generated these two new radioiodines. One of the goals of both groups was the treatment of hyperthyroidism. Hertz and Roberts were the first to do so on March 31, 1941; Hamilton and John Lawrence, Ernest's brother, began on October 12, 1941. By 1942, the United States was actively fighting in World War II. That year both Boston and Berkeley groups have preliminary data on the treatment of hyperthyroidism in Atlantic City; both showed that it was effective and went on to treat more patients. In Berkeley the therapy was viewed cautiously, and, in many case, the physicists were mainly occupied with work for the Manhattan District. In Boston Hertz used the therapy as often as he could, emphasizing the use of 130I, until he joined the U.S. Navy in 1943. Earle Chapman, a clinician on the voluntary staff of the MGH, took over Hertz's practice in 1943; their later differences over the precise treatment and who was in charge led to their falling out. After Hertz's release from the Navy he was not permitted to return to the MGH and became quite bitter; Chapman stayed on at the MGH. After the war was over, both had acquired a sufficient number of patients--there was then no such thing as a controlled trial--and wrote up the results for publication. Each wrote a different physicist, Hertz with Roberts and Chapman with Evans. When Hertz learned that Chapman's paper was being considered by the Journal of the American Medical Associations, he quickly sent his manuscript to JAMA as well. Although the editor of JAMA was puzzled by two papers on the same topic from the same institution, both papers appeared in the same issue of JAMA on May 11, 1964, and announced the new therapy was effective treatment for hyperthyroidism.