I graduated from Colegio Nacional de San Isidro in Buenos Aires, Argentina and completed my medical degree at Buenos Aires University School of Medicine. My surgical and urological residency were spent at the Hospital Italiano in Buenos Aires. I was an attending Urologist at Hospital Roffo in Buenos Aires until I came to the United States. At that point I was a Urology Fellow working on a research project at the Children’s Hospital and Harvard Medical School in Boston. I completed his American residencies in urology and surgery at the University of Massachusetts.

I enjoy spending time with my wife and three children.

My job is ultimately about the trust that comes from a long-term relationship.  I am honored that people choose me to care for them and their extended families, and I do my best to give thoughtful and evidenced based advice.  Each of us has unique goals for our long term health, and I really enjoy giving people guidance in this realm.  I also enjoy the challenge of my work.  Each day is extremely diverse and forces me to stay continually current.  When I am not at work, I love competing in triathlon and cycling events, skiing, travel, and being outside.  I also adore being a father to my three daughters.

Being a physician is an honor and a privilege I have enjoyed since graduating from The Johns Hopkins University School of Medicine in 1979.  As my patients know I am interested in your life, your passions and the Orthopaedic issues that frustrate you and how I might be of assistance to you.  Surgery is not always a solution.

I take care of newborn infants and their great grandmothers.  In an era of sub-specialization, I am the "silver haired" General Orthopaedist but have maintained my surgical skills and remain confident in my abilities.  I have been fortunate to have treated multiple generations of my friends and neighbors here on the South Shore and work in a hospital committed to clinical excellence and compassionate care.

My goal is to provide compassionate and equitable medical care to patients seeking care for breast-related concerns, including but not limited to breast lumps, abnormal screening mammograms, benign breast masses, and previous or current breast cancer diagnoses. 

I am a graduate of the Tufts University School of Medicine Physician Assistant and Masters in Public Health dual degree program. I have been working at the Dana-Farber Cancer Institute/Brigham & Women’s Hospital Division of Breast Surgery since June 2021.

It is my priority to provide care to patients that is skilled and supportive. I strive to accommodate a patient’s unique and individual needs such that all patients feel cared for and well-informed. I have professional interests in patient-oriented outcomes research and have studied coping and psychosocial wellbeing among adolescents and young adults with cancer. I am originally from Western Massachusetts, and my hobbies include hiking, skiing, and spending with family, friends, and my dog.  

William Tollefsen, MD is the EMS and MIH Medical Director for South Shore Health. Dual-boarded in Emergency Medicine and EMS Medicine, Dr. Tollefsen works clinically as an Emergency Physician at South Shore Health in addition to his role as EMS Medical Director.

One of few physicians in the country to receive the prestigious "FAEMS" recognition, Dr. Tollefsen is also the Medical Director for OEMS Region IV, serving 61 cities and towns of the Metro-Boston EMS Council. As the current EMS Medical Director for eight municipal and three private ambulance services on the South Shore, Dr. Tollefsen interacts and provides oversight for over 400 Paramedics.

Dr. Tollefsen graduated from New York Medical College and completed residency training in Emergency Medicine at Harvard University, Brigham and Women's, and Massachusetts General Hospital. He completed a fellowship in Emergency Medical Services and Critical Care Transport at the University of Massachusetts, where he worked as an Emergency Physician and Flight Physician for UMASS LifeFlight. He completed an MBA at the Isenberg School of Management at UMASS Amherst, and holds a Master of Medical Science degree from the Boston University School of Medicine.

A former pre-hospital provider, he is actively involved in EMS system design, paramedic education and Critical Care Transport Systems. He works closely with multiple EMS, Fire and Law Enforcement agencies throughout Massachusetts.

His research interests include systems of care, resuscitation, airway management, and paramedic education.