Engineering Researchers at Rensselaer
Polytechnic Institute Develop “Phantoms” To Make Medical
Imaging Safer for Overweight Individuals
Most medical imaging equipment is not designed with
overweight and obese patients in mind. As a result, these
individuals can be exposed to higher levels of radiation during
routine X-ray and CT scans.
A new study from Rensselaer Polytechnic Institute
is the first to calculate exactly how much additional radiation
obese patients receive from a CT scan. Research results show
the internal organs of obese men receive 62 percent more
radiation during a CT scan than those of normal weight men. For
obese women, it was an increase of 59 percent.
New technology developed at Rensselaer by nuclear
engineering expert X. George Xu could help solve this problem.
Xu’s research team created ultra-realistic 3-D computer models
of overweight and obese men and women, and used computer
simulations to determine how X-rays interact with the different
body types. These models, known as “phantoms,” can help empower
physicians to configure and optimize CT scanning devices in
such a way that minimizes how much radiation a patient
“Radiation exposure is cumulative over a patient’s lifetime.
The risk associated with a radiation dose from a single CT scan
is relatively small when compared with the clinical benefit of
the procedure. But patients are increasingly undergoing
multiple CT scans and other radiation-based procedures, which
can lead to unnecessary radiation risk. Regretfully, our study
shows that obese and overweight patients can be exposed to an
even greater level of radiation,” said Xu, head of the Nuclear
Engineering Program and a professor in the Department of Mechanical,
Aerospace, and Nuclear Engineering (MANE) at Rensselaer.
“Our new study brings us one step closer to minimizing
radiation exposure and mitigating this risk to patients.”
Results of the Xu’s study were published today in the
journal Physics in Medicine & Biology. The study
may be viewed online at: http://m.iopscience.iop.org/0031-9155/57/9/2441.
Currently, if technicians use normal equipment settings to
perform a CT scan on an obese patient, the resulting images are
blurry as the X-ray photons have to travel further and make
their way through layers of fat. As a result, technicians
generally adjust the equipment to a more powerful setting,
which produces a better image but exposes the obese patient to
additional radiation. There is no mechanism for discerning the
setting levels that will provide an optimal balance of the
highest image clarity and the lowest radiation dose.
These new phantoms for overweight and obese patients will be
part of a forthcoming software package, VirtualDose, developed
by Xu and his team. VirtualDose aims to enable the creation of
a personalized, ultra-realistic phantom of any patient
undergoing a CT scan. The program takes into consideration a
patient’s individual characteristics, including age, sex,
height, weight, and even if a woman is pregnant. By entering
these data into the software, VirtualDose quickly creates a
phantom that accurately models the patient’s internal organs.
These phantoms will allow physicians and researchers to compare
the radiation doses a patient will get from different CT
scanner settings, and then choose the most appropriate
VirtualDose will also enable physicians to keep a highly
accurate record of how much radiation patients are exposed to
over their lifetime. California recently became the first state
in the United States to require radiation dose records for
patients undergoing CT examinations.
Along with Xu, authors of the study are research associate
Aiping Ding; graduate students Matthew Mille and Tianyu Liu;
and lecturer and campus radiation safety officer Peter
Caracappa, all of the Nuclear Engineering Program and MANE at
The research is funded primarily by the National Institutes
of Health (NIH), with additional support from the National
Institute of Biomedical Imaging and Bioengineering, the U.S.
Department of Energy (DOE) Office of Nuclear Energy’s Nuclear
Energy University Programs (NEUP), and the Health Physics
The Nuclear Engineering Program at Rensselaer is among
the oldest in the nation, dating back to the late 1950s
when the university built an electron accelerator.
For more information on Xu’s research at Rensselaer,
Wall Street Journal: Scientists Find Safer Ways
To Test Medical Procedures
- Patient Safety: Reducing the Risks of Radiation Exposure
From CT Scans and X-Rays
- Safer, More Accurate Radiation Therapy for Expecting
- The Phantom Patient
- A Virtual Patient To Simulate Real-Time Organ
- Rensselaer Radiation Measurement and Dosimetry
- Nuclear Engineering Program