Dr. Ruth Williamson is a board-certified radiation oncologist based in Pasadena, California. She graduated from the Keck School of Medicine of USC and then did her internship at the VA Long Beach Healthcare System. She pursued her Radiation Oncology residency at the University of Southern California –LAC+USC Medical Center. Dr. Williamson has been practicing for more than 20 years and has treated patients with cancer using radiation therapy. At present, she is affiliated with the Huntington Memorial Hospital.