Dr. Poullos is a native of Stockton California. He attended Santa Clara University where he earned his BS in Biology. He received his M.D. degree at the University of Texas Medical School at Houston, after which he did Internal Medicine residency at the University of California-San Francisco, finishing in 2002. He stayed at UCSF as a Gastroenterology fellow until 2004. However, after a spinal cord injury, he decided to retrain in Radiology. He did his Radiology residency at Stanford University, where he also completed a fellowship In Body Imaging in 2009. Dr. Poullos is now faculty in both the departments of Radiology and Gastroenterology and Hepatology. His clinical practice is at the Stanford University Medical Center, where he interprets CT, MRI, and ultrasound primarily of the abdomen and pelvis. His interests include radiology of the acute abdomen, hepatobiliary imaging, and colorectal cancer screening.

Dr. Poullos is Founder and Executive Director of the Stanford Medicine Abilities Coalition (SMAC), a group composed of people with disabilities and their allies at Stanford Medicine. He is also a member of the Radiology Department Diversity Committee, the School of Medicine Faculty Senate Subcommittee on Diversity, and the School of Medicine Diversity Cabinet.