Our Company

Virtual Phantoms, Inc. is the creator of VirtualDose™, a family of web-based software tools that enable accurate radiation dose calculations.  With an exclusive license of “virtual patient” technologies developed at Rensselaer Polytechnic Institute (Troy, New York) and University of Florida, (Gainesville, Florida) , we are a world leader in deformable 3D/4D patient anatomical modeling and radiation dose calculations using the Monte Carlo methods.

Our initial product, VirtualDose™CT, is targeted to x-ray CT dose tracking and reporting. The dramatic rise in CT exposures has caused a patient safety crisis in the U.S. and around the world. CT dose reporting is now mandated in California and Texas, with other states looking at probable regulation in the near future.  VirtualDoseCT is currently the only CT dose reporting product that is based on the 3rd-generation deformable virtual-patient technologies that have been shown to be 50% more accurate than the stylized patient models.

Our Uniqueness

VirtualDoseCT is designed for ease of use by radiologists, technologists, medical physicists, regulators, manufacturers and researchers. It was developed through 20 years of research funded by the National Institutes of Health (NIH) and other government agencies and has been thoroughly tested in major U.S. hospitals. VirtualDoseCT uses a family of anatomically correct phantoms and revolutionary GPU-based Monte Carlo radiation simulation techniques to enable radiation health professionals to obtain highly accurate images with much greater patient safety.

Broad Recognition

The “virtual patient” research has received a great deal of attention from media sources such as The Wall Street Journal, U.S. News, Weekly US NEWS, MedicalPhysicsWeb, MedicalXpress, DailyRx Relevant Health News, MyhealthNewsDaily, SciGuru, and Science News.  Visit our Press Room page to read some of the recent articles about our unique technology, such as The Wall Street Journal article, which spoke highly of the cutting edge-virtual phantom technology developed by Dr. Ding.

Our History

Virtual Phantoms, Inc. was founded in 2009 by faculty members from Rensselaer Polytechnic Institute, in collaboration with the University of Florida, using the “Virtual Patient” technologies developed from nearly 20 years research at RPI and UF in the field of nuclear and radiological engineering. Combining a large collection of anatomically accurate models of patients of various ages and sizes and sophisticated “Monte Carlo” simulation methods originally developed for nuclear weapons research at Los Alamos in the 1940s, VPI is recognized as a world leader in the modeling of ionizing radiation, radiation safety, and medical/occupational radiation dosimetry.

Management Team

Dr. X. George Xu, Founder
President and Chief Executive Officer

Microsoft Word - Document2Dr. Xu is currently Professor of Nuclear and Biomedical Engineering at Rensselaer  Polytechnic Institute (Troy, New York). He is also the director for Center for Engineering-Based Patient Modeling. In addition, he holds adjunct faculty appointments in Medical Physics at Albany Medical College (Albany, New York) and Harvard Medical School (Boston, MA).

Dr. Xu pioneered many methods in organ dose calculations using 3D/4D patient models, including the world’s finest whole-body dosimetry models, VIP-Man, developed in 2000 from the famous Visible Human Project. Dr. Xu is a fellow of American Association of Medical Physicists (AAPM), Health Physics Society (HPS), and American Nuclear Society (ANS).


Dr. Peter F. Caracappa, Chief Technology Officer

Microsoft Word - Document2Dr. Caracappa is a Certified Health Physicist by the American Board of Health Physics, with 10 years experience in positions such as Radiation Safety Officer (RSO) and faculty member in the nuclear engineering program at Rensselaer Polytechnic Institute. In his role as the RSO, Dr. Caracappa is responsible for broad-scope academic licenses for the use of radioactive materials, and for supervising the health physics for a research, training, and test reactor licensed by the US Nuclear Regulatory Commission.  He has a broad array of operational health physics experience, including high-energy electron accelerators, and low-power research reactors, physics and chemistry laboratories.  As a faculty member, Dr. Caracappa has taught courses in radiation detection and instrumentation, health physics, nuclear physics, and laboratory experimentation, and has supervised many undergraduate research capstone design projects. Dr. Caracappa has made important contribution to the research literature in radiation dose calculations, especially related to dose to the bones as well as for the dose assessment for patients who are exposed to CT examinations.


Mr. John Crossin, Chief Operating Officer

Microsoft Word - Document2Mr. Crossin has over 30 years of experience helping startups and small companies grow. His experience ranges through all phases of company growth from initial concept through acquisition and IPO. He has an extensive engineering background, and has also developed a successful track record and outstanding reputation as a management executive who consistently delivers to growth goals while maintaining fiscal responsibility.

Mr. Crossin has held CEO and COO positions with several startup companies in a number of industries. Prior to his management career, he served in a wide range of roles; from development engineer to production manager to support coordinator. He holds BSME and MEME degrees from Rensselaer Polytechnic Institute and MS in Engineering Management from Worcester Polytechnic Institute. He is a Registered PE in Massachusetts.

Dr. Aiping Ding, Manager, Software Engineering

Microsoft Word - Document2Dr. Ding performed his PhD research at RPI in the areas of anatomical modeling, Monte Carlo dose calculations, and software development of VirtualDoseCT for monitoring and analyzing CT radiation dose.  Dr. Ding is an expert in the modeling of 3D/4D deformable patient anatomy, CT scanner, and clinical CT protocol.  Dr. Ding has been playing a key role in a multi-year NIH project involving RPI, the University of Florida, and several clinical partners.  At RPI, Dr. Ding provided key expertise in the use of triangular mesh geometries to define human organs of certain shape and size.  His work allowed the research team to create a group of adult models with different organ sizes following a distribution pattern found in population surveys.  His work on obese patients, for example, made it possible for the first time in biophysics research to create 3-D models of individuals who are considered to be overweight, obese (I, II), and morbidly obese.  Under his leadership, VirtualDoseCT is designed as a “Software as a Service (SaaS)” to allow as many users as possible to access it simultaneously via the Internet.  The most significant advance in radiation dose practice brought on by VirtualDoseCT is the comprehensive organ and effective dose database it contains, which emerged from many Monte Carlo simulations involving CT scanner models and anatomically realistic phantoms. VirtualDoseCT integrates this database to allow a user to specify several variables, including patient type, clinical protocol, and scanner parameters (i.e., scanning time, voltage, tube current, and pitch), all to customize radiation doses for specific patients.  VirtualDoseCT also enables physicians to keep a highly accurate record of how much radiation individual patients receive over their respective lifetimes.