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.

My treatment philosophy and focus is to diagnose and treat patients ages 15 – 100 whom have a variety of breast issues including but not limited to infection, pregnancy related breast issues, genetic risk for cancer, abscesses, skin disorders, abnormal breast imaging, breast lumps, and past or current personal history of breast cancer.

I've been an RN since 1981, working in Internal Medicine, Oncology, and Ventilator Care. I've been a NP since 1996. I'm a graduate of Columbia University in Adult Health and Oncology. I worked in New Jersey for 20 years in Internal Medicine and combined Oncology prior to relocating to Massachusetts in 2003.

Certified by ANCC, ONCC, ANCC.

Liana MacDonald is a Women’s Health Nurse Practitioner. She graduated from Regis College with a Master of Science in Nursing in 2020. She obtained her Bachelor of Science in Nursing from the University of Massachusetts Boston in 2016 and began her nursing career in the Emergency Department. She has been working as a Labor and Delivery nurse since 2019.

Liana is passionate about health equity and eliminating the gap in care amongst different races and ethnicities. She is proud of her focus on adolescent health, substance use disorders in pregnancy, and trauma-informed care.  

When not at work, Liana can be found spending her time with family, friends, and her rescue dog. She loves to travel to new cities and countries and learn about different cultures. She also loves to give back to her community.