In a seminal paper published in 1946, Robert R. Wilson, PhD proposed using accelerator-produced beams of protons to treat deep-seated tumors in humans. Eight years later, the first cancer patient received proton therapy treatment at the Berkley Radiation Laboratory. Over the next four decades, proton therapy programs were launched at Harvard University (1961), the University of California, Davis (1964) and the Los Alamos National Laboratory (1974). In 1990 the first hospital-based proton therapy center opened.