Dr. Janson grew up in Lawrence, New York. He is a graduate of the New York University School of Medicine. He did his internship and residency at Bellevue Hospital in New York City, followed by a three-year fellowship in gastroenterology at Duke University Medical Center, where he received advanced training in operative gastrointestinal endoscopy. He entered practice in Virginia Beach in 1990.

Dr. Janson has served as both Chairman of the Department of Internal Medicine and President of the Medical Staff at Sentara Virginia Beach General Hospital. He and his wife, Trina, have three sons and two daughters. Dr. Janson is an avid reader and golfer and is involved in youth sports.