The Alan H. Porter, M.D., & Claudia B. Porter, R.N., Department of Radiation Oncology proudly welcomed three new residents on July 1, 2026: physician residents Berkeley Sirmans, MD, and Ian Tsekouras, MD, and medical physics resident Lixiang Guo, PhD.
Dr. Guo earned his Ph.D. in Biomedical Engineering–Medical Physics from UT Southwestern Medical Center, where his research focused on mechanistic modeling and dosimetry for FLASH radiotherapy, and included radiation dosimetry, treatment delivery optimization, and improving the safety and precision of cancer treatments. His presentations and publications have been recognized by the American Association of Physicists in Medicine and published in the journal Medical Physics.
Dr. Sirmans earned his medical degree from St. George’s University School of Medicine. He has conducted clinical and translational research with Florida Cancer Specialists, where he contributed to case reports published in an American Society of Clinical Oncology (ASCO) journal exploring unique breast, colon and prostate cancer presentations in an aid to improve patient outcomes. His research interests include proton therapy, pediatric radiation oncology, and improving patient access to high-quality cancer care.
Dr. Tsekouras earned his medical degree from the University of Alabama at Birmingham Marnix E. Heersink School of Medicine, where he conducted research focused on improving cancer treatment strategies, including studies examining radiation therapy utilization, small cell lung cancer treatment approaches, and proton therapy. His research interests include treatment optimization, advancing personalized radiation therapy approaches, and improving access to care for underserved communities.
