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Pushing the envelope of technology
Pushing
the
envelope
of
technology
at the Ginzton Technology Center
n e w s f o r t h e r a d i a t i o n t h e r a p y c o m m u n i t y o c t o b e r
2 0 0 3
POINT OF VIEW
| Online, real-time IGRT: The
next step in technology evolution
EVERY BREATH YOU
TAKE
| A look at advances
in image-guided motion management
IMRT IN JAPAN
| Clinicians at Kyoto University
Hospital develop IMRT expertise PUSHING
the
TECHNOLOGICAL
ENVELOPE
at the Ginzton Technology Center
BEHIND THE SCENES
Stories about those who explore new scientific fron-
tiers or push the envelope of technology have always
been popular. Endeavors that go beyond convention-
al boundaries seem to spark our curiosity and compel
us to wonder: Whats next? Pushing hard on the tech-
nological envelope to explore whats next for Varian
Medical Systems are the scientists and engineers at the
Ginzton Technology Center.
By Lynn Yarris
1 0
c e n t e r l i n e
o c t o b e r
2 0 0 3 Headquartered in Mountain View, California, with a staff of
about 45, the Ginzton Technology Center (GTC) is Varians
central research and development organization. Although it
officially came into existence in 1999 (when Varian Medical
Systems was organized into three operations, including
Oncology Systems and X-Ray Products), GTC has existed
under different names since the 1960s, when it was known
as the Varian Research Center.
New technologies, new capabilities
Although GTCs mission entails problem solving and the
incubation of start-up businesses, its main thrust has been the
investigation and development of new or so-called disrup-
tive technologies that will create significantly improved capa-
bilities for Varians customers.
One of our main jobs is to take as much risk as possible
out of a new technology, says GTCs director, George
Zdasiuk, Ph.D. We investigate a promising idea and work
with Oncology Systems marketing and engineering teams to
assess whether it will one day result in a meaningful product
or service.
Zdasiuk, who holds his Ph.D. in applied physics from
Stanford University, says the horizon for most of the tech-
nologies GTC investigates is three to five years.
To go much further than that would be questionable in
the current environment, given how fast technological
changes occur, he says. We try to look as far into the future
as we think we can see while still retaining the flexibility to
respond to new breakthroughs and changes in technology.
Zdasiuk says the line separating technologies ready to be
made into products from those that are premature is not
always solid. For this reason, the GTC staff will do a prelimi-
nary investigation into an idea and, if they judge it to have
sufficient merit, theyll seek the involvement of Varians mar-
keting group.
Varians marketing and engineering departments stay
closely connected to our clinical customers, says Kolleen
Kennedy, vice president of Oncology Systems, who oversees
both marketing and engineering functions at Varian. We
work with our colleagues at the GTC to ensure that our com-
plementary resources are focused on solving the most press-
ing clinical problems our customers face.
Flat-panel imaging developments
Probably the best example of a seedling technology that GTC
researchers helped nurture into the full bloom of a commer-
cial product is the flat-panel X-ray imager.
Its no exaggeration to say that flat-panel technology is rev-
olutionizing the use of X-ray imaging both inside and outside
the medical community. Technology specifically developed at
GTC and elsewhere within Varian makes it possible to obtain
both high-resolution radiographs and real-time X-ray movies
from the same camera. It also gives X-ray imaging unprece-
dented portability, which is helping to substantially broaden
the technologys range of applications.
We began working with researchers from Xeroxs Palo
Alto Research Center (PARC) in the early 1990s to develop
the early prototypes for flat-panel imagers based on amor-
phous silicon technology, Zdasiuk says. At that time, many
thought this technology would be too expensive or not robust
enough for radiation oncology. But, working with Varians
engineering department, we were able to incorporate it into
an FDA-cleared, amorphous siliconbased portal imaging
product.
>
Left, researchers Gary Virshup, Edward Seppi, Ph.D., and
John Pavkovich, Ph.D., explore the future of radiation
technology at Varians Ginzton Technology Center.
Above right, on the drawing board are advancements
in linac onboard imaging systems.
We work with our colleagues at the GTC to ensure that
our complementary resources are focused on solving
the most pressing clinical problems our customers face.
Kolleen T. Kennedy, M.S., vice president, Varian Oncology Systems
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c e n t e r l i n e
o c t o b e r
2 0 0 3 Today, Varians most advanced flat-panel imager is the
PaxScan
®
4030A detector, a 40- by 30-centimeter panel that
can acquire high-resolution radiographs at more than 7
frames per second (FPS), or fluoroscopic images at up to 30
FPS. The market for the PaxScan displays is still growing, but
GTC researchers are already at work on the next stage of
development.
Varian currently deploys what is called an indirect
approach to flat-panel imaging. Incoming X-ray photons are
absorbed by a scintillator coating that converts them to visi-
ble light photons, which are then converted into an electrical
signal in an amorphous silicon plate. The electrical signal is
amplified, digitized, and finally transformed into an image by
a computer. Researchers at GTC are now exploring the use of
other coatings that would directly convert incoming X-ray
photons into electrical signals.
The main advantage of taking the indirect approach to
flat-panel imaging is the potential to achieve higher resolu-
tion at a lower cost, says Zdasiuk.
The promise of cone-beam CT
Another major research effort under way at GTC is the devel-
opment of cone-beam computed tomography (CT). In con-
ventional fan-beam CT, a thin, flat X-ray beam is sent
through a designated target within a patients body from
many different angles. This yields a series of projections that
can be reconstructed by a computer into a single, high-reso-
lution 2D image. In cone-beam CT, the fan beam is opened
up (into a cone) to cover a broad enough area so that an
entire 3D-image data set can be obtained in a single scan.
Cone-beam CT greatly speeds up the collection of data,
especially when we think of the relatively slow gantry rotation
speeds of radiation oncology accelerators and treatment sim-
ulators, says Zdasiuk. A volume set that might take the bet-
ter part of an hour to collect using fan-beam CT on a simula-
tor can be acquired in about a minute with cone-beam CT.
Working closely with Varian Oncology Systems worldwide
engineering team, GTC researchers have been feverishly at
work incorporating cone-beam CT technology into Varians
Acuity simulator, Zdasiuk says. This addition will give
oncologists a new option of using the Acuity system to obtain
high-resolution 3D anatomical images.
Instead of having to physically move the patient and tie up
a CT scanner, oncologists will be able to combine imaging
modalities during treatment simulation, says Zdasiuk.
Giving Acuity a 3D CT capability also helps ensure that
patient positioning is optimized for treatment.
Varian is looking to demonstrate a prototype of Acuity
with cone-beam CT technology at this years annual ASTRO
meeting. The eventual plan is to incorporate cone-beam CT
technology onto a Clinac® linear accelerator for kV-based
onboard imaging. Onboard imaging would provide oncology
teams with high-resolution images of both bony anatomy,
for interfraction patient positioning, and soft tissues, for
intrafraction motion management.
BEHIND THE SCENES
GINZTON TECHNOLOGY CENTER
R&D program manager
George Zentai, Ph.D., demonstrates the
prototype for a photo-conductorbased
flat-panel imager in GTCs Advanced
Development Lab.
1 2
c e n t e r l i n e
o c t o b e r
2 0 0 3 IGRT enhancements
As part of the next step in Varians initiative for image-guid-
ed radiation therapy (IGRT), GTC researchers are working to
develop a new generation of motion-tracking technology for
monitoring the target movement. GTC researchers helped
develop the RPM respiratory gating system, which uses a
reflective marker placed on the patient's chest, in combination
with a video camera, to track patient motion during respira-
tion.
The idea first surfaced back in the early 1990s when we
saw that the a