City of Hope staff gathered in April 1955 for this photo commemorating the arrival of a truck that transported radioactive cobalt from the U.S. Atomic Energy Commission in Oak Ridge, Tenn. The truck traveled 3,500 miles to Duarte, Calif., stopping at 14 cities before reaching City of Hope.

In the Cold War era, new therapeutic devices using radioactive cobalt represented the initial steps in harnessing the atom to fight cancer. City of Hope’s Melville Jacobs, M.D., and Cheng Wu Li, Ph.D., designed their new cobalt 60 teletherapy unit to use radiation to treat tumors deep in the body. Planning and manufacturing took two years and cost $35,000 — a fraction of the cost of existing units at the time. It was seen as a prototype that would make the low-cost cancer “bombs” more widely available to hospitals.

According to Jacobs, the instrument provided more than 100,000 individual therapies in two decades. “So simple and so effective were its concept and construction,” he remembered, “that this unit recorded downtime of less than two weeks across its 20 years of use.” After a linear accelerator replaced the cobalt unit in 1975, City of Hope donated it to the Smithsonian Institution.