Dr. Leeman specializes in the treatment of prostate cancer as well as MRI-guided and adaptive radiotherapy treatment for multiple cancer types. He serves as the Director of Adaptive Radiotherapy (MRI and CT guided) in the BWH/DFCI Department of Radiation Oncology. He received his AB from Harvard College and is a graduate of the Physician Scientist Training Program at the University of Pittsburgh School of Medicine. He completed his internship and residency in radiation oncology at Memorial Sloan Kettering Cancer Center in New York, NY where he served as Chief Resident. 

His research focuses on the application of MR imaging technology and adaptive radiotherapy for the advancement of prostate cancer and kidney cancer treatment to improve outcomes by reducing toxicity of treatment and improving tumor control. He also studies biomarker development to predict response to androgen deprivation therapy and radiotherapy and the role of prostate radiotherapy in patients with metastatic prostate cancer. He serves as the principal investigator of multiple clinical trials including a master protocol for studying MRI guided adaptive radiotherapy for multiple cancer types, a phase I/II randomized trial evaluating a gadolinium-based theranostic nanoparticle for radiosensitization with MRI guided adaptive SBRT and a multi-center prospective trial evaluating CT-based adaptive prostate SBRT with urethral sparing.