Maria A. Thomas

Maria A. Thomas is an Associate Professor of Radiation Oncology at Washington University School of Medicine, with dual appointments in the Institute of Clinical and Translational Sciences (ICTS) and Siteman Cancer Center. She specializes in radiation therapy for cancer treatment, particularly breast cancer, with expertise in all modalities of external beam radiation including 3-D conformal treatment planning, IMRT, stereotactic body radiotherapy, image guided radiation therapy, and accelerated partial breast irradiation. She also specializes in brachytherapy and Gamma Knife radiosurgery.

Dr. Thomas completed her educational journey with a BS in Biology from Creighton University (2000), followed by a Medical Degree and PhD in Molecular Microbiology and Immunology from Saint Louis University School of Medicine (2008). She completed her residency in Radiation Oncology at Barnes-Jewish Hospital/Washington University School of Medicine (2013).

Dr. Thomas's research focuses on advancing radiation therapy techniques for breast cancer treatment, with particular emphasis on heart-sparing radiotherapy, accelerated partial breast irradiation, and MRI-guided radiation therapy. Her work explores innovative approaches to minimize cardiac toxicity while maximizing tumor control, including deep inspiration breath hold techniques and advanced imaging modalities. She has made significant contributions to understanding dosimetric differences in various radiation delivery systems and developing quality assurance frameworks for emerging technologies like deep learning-based segmentation.

Her recent publications (2019-2025) demonstrate a strong focus on breast cancer radiation therapy, particularly in the areas of accelerated partial breast irradiation, cardiac protection during breast radiation, and advanced imaging techniques for treatment planning. She has published extensively on strut-adjusted volume implant techniques, MRI-guided radiotherapy, and predictors of outcomes in triple-negative breast cancer. Her work bridges clinical practice with technological innovation, particularly in the application of artificial intelligence to radiation oncology.

• 39 research publications spanning from 2006 to 2025
• Over 1,312 citations
• Recognized as Top Doctors®
• Early career research on oncolytic adenovirus vectors

As an active clinician-researcher, Dr. Thomas maintains clinical appointments at multiple facilities including the Center for Advanced Medicine Siteman Cancer Center and Siteman Cancer Center – South County. She is affiliated with several hospitals including Alton Memorial Hospital, Barnes-Jewish Hospital, Barnes-Jewish St. Peters Hospital, Barnes-Jewish West County Hospital, and Christian Hospital.