Dr. Barrett received a bachelor's degree in physics from Virginia Polytechnic Institute in 1960, a master's degree in physics from MIT in 1962, and a Ph.D. in applied physics from Harvard in 1969. He worked for the Raytheon Research Division until 1974, when he came to the University of Arizona. He is a Regents Professor in the College of Optical Sciences and the Department of Medical Imaging in the College of Medicine, and he has appointments in Applied Mathematics, Biomedical Engineering and the University of Arizona Cancer Center. He is a fellow of the Optical Society of America, the Institute of Electrical and Electronic Engineers, the American Physical Society, the American Institute of Medical and Biological Engineering and the International Society for Optics and Photonics (SPIE).
His research is in image science, with applications in medicine, astronomy and optics. He is founder and co-director of the Center for Gamma-Ray Imaging, a Biomedical Technology Resource Center funded by NIBIB. Now in its twentieth year, the Center develops state-of-the art instruments, algorithms and radiotracers for preclinical studies. A particular interest is in developing imaging methods that will open up new possibilities for personalized cancer therapy.