Dr. Calhoun earned a Bachelor of Science degree in Biology from the University of Illinois at Chicago and a Doctor of Medicine degree from the University of Kansas School of Medicine. Following a residency in internal medicine at Northwestern University, he completed a fellowship in Clinical Nephrology, Hypertension, and Metabolism at the University of Chicago.  Following a very successful career in private practice, Dr. Calhoun aggressively pursued his passion in academic medicine.  After academic leadership positions at the University of Missouri Kansas City, he served 10 years at the UT Medical Branch at Galveston (UTMB) as an Associate Professor of Medicine and Corporate Medical Director of UTMB HealthCare Systems.  He then became simultaneously the Senior Vice President at Parkland Hospital and the Associate Dean for Clinical Affairs at the UTSW Medical School.

From 2002 to 2020, Dr. Calhoun served as President of The University of Texas Health Science Center at Tyler, during which time the campus grew significantly and became a SACSCOC-accredited academic institution.  In 2020, he was selected as the President of the newly consolidated UT Tyler, which merged the academic and health science center campuses in Tyler.  He is a Professor of Medicine.

President Calhoun is the immediate Past-Chair of the American Association of Medical Colleges Board of Directors. He is on the Executive Committee, and is the Past-Chair, of the AAMC Council of Teaching Hospitals. Dr. Calhoun is the only individual to serve two terms as Chairman of America’s Essential Hospitals, formally the National Association of Public Hospitals.  He also served two terms on the DSHS Council (the Texas State Board of Health) and he currently serves on the Executive Committee of the Teaching Hospitals of Texas. 

Dr. Calhoun is Chairman of the Board for the UT Health East Texas Health System, acquired in March 2018.  This newly formed health system owns and operates 10 hospitals, over 50 clinics, emergency transport services, a home health agency, and other health related enterprises. 

UT System Board of Regents approved a new UT Tyler School of Medicine in 2020, a culmination of Dr. Calhoun’s healthcare vision for East Texas. 

Dr. Calhoun has received numerous awards for his work in healthcare, public health, higher education delivery, and community service, including the prestigious Doctor Luke Society, where he was inducted in 2021.  He and his wife, Jeanette, were awarded the T.B. Butler Citizens of the Year Award in 2021, honoring both their contributions and their achievements for the city of Tyler, Texas.