Our Faculty: Physicians and Physicists

At Stony Brook Medicine, experienced radiation oncologists work with other members of the Radiation Oncology team to treat patients with cancer. The team uses a wide range of radiation therapies and advanced techniques-all with the goal of killing cancer cells and sparing healthy tissue from damage. 


Samuel Ryu, MD
Professor and Chair,  Radiation Oncology, and Deputy Director, Clinical Affairs, Stony Brook University Cancer Center

Board Certification: Radiation Oncology 

Language (other than English): Korean
Recognition: America’s Top Doctors, 2005 to present (Castle Connolly) and Top Doctors List from Hour Detroitmagazine, 2005 to 2013; America’s Top Oncologists of Consumers’ Research Council of America, 
2006 to present

Specialty: Brain and Spine cases, Benign tumors, Head and Neck cancers

Personal Statement: I am at the forefront of high technology radiosurgery of brain and spine tumors. I give my constant effort to compassionate use of these treatments for my patients. I try to be on the patient's perspective and care about the patient's well-being.

For more information about Dr. Ryu, click here 


Alexander M. Stessin, MD, PhD
Assistant Professor, Radiation Oncology 

Board Certification: Radiation Oncology  

Medical School: Rockefeller University, Sloan-Kettering Institute, and Weill Cornell Medical College; MD and Ph.D. in medicine/pharmacology from tri-institutional MD/Ph.D. program
Residency: New York-Presbyterian 
Hospital/Weill Cornell Medical College; transitional year residency at St. Vincent's Medical Center, Bridgeport, CT; Radiation Oncology

Specialty: Gastrointestinal Cancers, Breast Cancers, Brain and Child Tumors

For more information about Dr. Stessin, click here


Edward Valentine, MD
Clinical Assistant Professor,  Radiation Oncology 

Board Certification: Radiation Oncology 

Language (other than English): French
Medical School: New York Medical College
Residency: Memorial Sloan-Kettering Cancer Center, Radiation Oncology
Fellowship: Memorial Sloan-Kettering Cancer Center, Radiation Oncology

Specialty: Women's Cancers, Leukemia and Lymphomas, Head and Neck Cancers

For more information about Dr. Valentine, click here 


Kartik Mani, MD, PhD
Clinical Assistant Professor, Radiation Oncology 

Medical School: Albert Einstein College of Medicine, Bronx, NY
Residency: St. Luke's-Roosevelt Hospital Center, New York, NY

Residency: Montefiore Medical Center, Bronx, NY

Specialty: Lung Cancer, Head and Neck Cancer, Gastrointestinal Cancer, Prostate Cancer, Brain Tumor, Stereotactic Body Radiotherapy (SBRT), Biomedical Information


Clare M. Moran, DNP, FNP, RN

Family Nurse Practitioner, Radiation Oncology

Board Certification: Family Nurse Practitioner

Doctor of Nursing Practice: Stony Brook University Master of Science in Nursing

Family Nurse Practitioner: Columbia University Bachelor of Science in Nursing: Binghamton University


Bruce Demple, PhD

Ph.D., Biochemistry, University of California, Berkeley

B.A. Biology, Wesleyan University


Zhigang Xu, PhD

Associate Professor, Radiation Oncology, and Director of Medical Physicist

Board Certification: Therapeutic Radiologic Physics 

Specialty: HDR Brachytherapy, Machine, and Quality Assurance, Radiation Shielding Design, Secure Electronic Medical Records Sharing using Blockchain Technology


Jinkoo Kim, PhD

Associate Professor, Radiation Oncology, Medical Physicist

Board Certification: Therapeutic Radiologic Physics 

Specialty: Image-Guided Radiation Therapy, Deformable Imaging Registration, SRS/SRT/SBRT New Platform Treatment


Xin Qian, PhD

Assistant Professor, Radiation Oncology, Medical Physicist

Board Certification: Therapeutic Radiologic Physics 

Specialty: Image-Guided Radiation Therapy, Small Field Dosimetry, 3D Dosimetry


Avraham Dilmanian, PhD
Professor of Research, Departments of Radiation Oncology, Neurology, and Radiology   

Research Interests

  • Experimental methods of radiation therapy utilizing the tissue-sparing effects of arrays of parallel, thin or small x-ray or particle beams.  The arrays are referred to as microbeams when thinner than 0.3 mm, or minibeams if they are 0.3 to 0.7 mm thick. The method has been applied to preclinical research in the treatment of the intracranial and subcutaneous tumors as well the spinal cord injury research.
  • X-ray imaging, including the establishment of the performance of the truly monochromatic CT and the development of the CT image reconstruction routine for diffraction-enhanced imaging.•The use of contrast agents including gold nanoparticles to preferentially enhance tumor damage in radiation therapy and in hyperthermia. Experimental radiation therapy.