Rensselaer researchers awarded major NIH grant to
develop 4-D virtual patient model
Troy, N.Y. — With a $2 million grant from the National
Institutes of Health (NIH), researchers from Rensselaer
Polytechnic Institute are developing a physics-based virtual
model that can simulate a patient’s breathing in real time.
When used in conjunction with existing 3-D models, adding the
fourth dimension of time could significantly improve the
accuracy and effectiveness of radiation treatment for lung and
liver cancers.
X. George Xu, professor of nuclear and biomedical
engineering, and Suvranu De, associate professor of mechanical
engineering, have formed a multidisciplinary collaboration with
clinical colleagues at the Cancer Therapy & Research Center
in San Antonio, Texas, to develop the 4-D Visible Photographic
Man (VIP-Man). This virtual model is an extension of Xu’s
ongoing project involving the 3-D VIP-Man, which is an advanced
computer model that simulates in 3-D how radiation affects the
organs and tissues in the human body.
“Live patients are not static beings, and a moving organ
such as the lung or heart is a main concern in radiation
treatment or imaging of tumors that are affected by such organ
movement,” Xu said. “In order to determine accurate and
effective radiation dosages, doctors must consider such issues
as the breathing function and air volume change that are
affected by several physiological factors over the course of
the radiation treatment.”
Real-time simulations could allow doctors to spot the small
fractions of time when the lungs, liver, kidneys, and
eventually the heart, are stationary relative to the external
radiation beams. These opportune moments during the actual
therapy mean that doctors will have more confidence delivering
the radiation to a moving tumor.
"The 4-D VIP-Man will allow doctors and medical physicists
to accurately predict and monitor these anatomical changes to
provide the most effective treatment possible at any given
time," Xu said.
The fourth dimension of the VIP-Man is not easily achieved,
according to Xu. Currently Xu and De are focusing their energy
on respiratory function. “Using advanced computational tools,
it is possible to simulate lung movement; however, not in real
time,” De said. “For effective radiation therapy, physics-based
real-time performance offers the ultimate solution.”
The key challenge in this project is to develop the
algorithms that will make the virtual lungs and adjacent
tissues move in real time according to realistic tissue
biomechanical properties, De said.
Xu expects that the physics-based 4-D VIP-Man will
eventually be used as an even more general anatomical modeling
tool for the biomedical community to help patients with
respiratory and cardiac diseases. At the same time, Xu will
continue to work on the 3-D VIP-Man to create a "family" of
virtual patients, ranging in ages and sizes, in collaboration
with researchers worldwide through the Consortium of
Computational Human Phantoms (www.virtualphantoms.org),
co-founded by Xu.
The collaboration with the group in Texas came about when
Xu’s former student, Chengyu Shi, a clinical medical physicist,
and Martin Fuss, a radiation oncologist, expressed their
interests to develop better radiation treatment by accounting
for lung movement. Xu contacted De, who had been using the 3-D
VIP-Man to simulate tissue deformation for surgical procedures,
and the idea to take 3-D VIP-Man into the fourth dimension was
born.
Xu has been working on the 3-D VIP-Man since 1997 using the
original Visible Human Project dataset provided by the National
Library of Medicine, also funded by several grants from NIH as
well as a National Science Foundation CAREER grant. The new
four-year, $2 million grant is funded by the National Library
of Medicine, which is part of NIH.
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