Download Image-Guided Radiation Therapy and Dynamic Adaptive

Technology & Services
Image-Guided Radiation Therapy and Dynamic Adaptive Radiotherapy—
Targeting Moving Tumors
a report by
Va r i a n M e d i c a l S y s t e m s
At the Karolinska Institute in Stockholm, Sweden, JanOlov Carlsson lies on a treatment couch under a
medical linear accelerator. He is ready to receive his
daily dose of radiation for prostate cancer. An X-ray
system on robotic arms slides into place on either side
of his body, then rotates around him, taking images to
pinpoint the tumor’s exact location. In a control room,
clinicians monitor computers that match the images
with Carlsson’s treatment plan to see if the tumor has
shifted. It has. Within seconds, the coordinates needed
to put Carlsson’s tumor into perfect alignment with the
radiation beam are calculated.Then, with the push of a
button, Carlsson’s therapists adjust the couch and
position him for the treatment.
Sixty-year-old Carlsson is one of more than a dozen
patients at the Karolinska Institute where Varian
Medical Systems technology for delivering imageguided radiation therapy (IGRT) is helping doctors
locate and target tumors with unprecedented speed and
precision. The institute’s medical linear accelerator, a
machine that generates the radiation beams used to kill
cancer cells, is fitted with Varian’s On-Board Imager™,
a device for tracking tumor positions with X-rays at the
moment of treatment to ensure that radiation beams are
hitting the target with sub-millimeter accuracy.
“IGRT is a significant incremental improvement in
accuracy and the ability to deliver more radiation safely,”
according to Munther Ajlouni, MD, radiation oncology
director at the Henry Ford Health System in Detroit,
Michigan, and an early adopter of the On-Board
Imager. Ajlouni and other doctors expect that IGRT
will be an important weapon for combating many types
of cancer.
Varian has led the field in the practical implementation
of IGRT technology with more than 275 orders and 110
shipments of the automated, robotically controlled
On-Board Imager devices for IGRT since their
introduction in late 2004. Varian’s IGRT products also
facilitate four-dimensional (4-D) treatments by
correcting tumor motion caused by respiration during
treatment. This capability holds special importance for
the treatment of lung cancer, which is currently the most
common and one of the most lethal forms of cancer.
BUSINESS BRIEFING: US ONCOLOGY REVIEW 2006
Interfraction and Intrafraction
M o t i o n — I G R T a n d D y n a m i c Ta r g e t i n g
Tumors do not stand still. They move between and
during daily treatments.They shrink as they respond to
treatment.They are subject to ‘interfraction’ motion due
to unavoidable day-to-day variations in anatomy or in
how patients are positioned for treatment, and are
subject to intrafraction motion due to respiration. Daily
imaging with the On-Board Imager device enables
clinicians to adjust treatment for interfraction motion,
or variations in patient set-up from day to day during a
course of treatment.
To accommodate intrafraction motion as a result of
breathing, Varian offers the Real-time Position
Management (RPM™) respiratory gating system, which
is used to synchronize imaging and dose delivery with a
patient’s breathing cycle. Respiratory gating makes it
possible to track the position of tumors that can move as
much as four centimeters (more than 1.5 inches) as the
patient breathes. Varian’s RPM respiratory gating
system—in place in more than 300 cancer centers
around the world—uses an infrared camera to track a
special marker placed on the patient’s diaphragm.
Breathing can be monitored while taking computed
tomography (CT) scans for treatment planning, as well as
during treatment sessions, allowing doctors to pick the
best moment in a patient’s breathing cycle to turn on the
beam. As a result, the margin of treatment around the
tumor can be significantly reduced and the total dose to
the tumor can be increased without fear of harming the
surrounding healthy tissue.
The Era of Dynamic Adaptive
Radiotherapy
With the advent of IGRT, new opportunities for
personalized cancer care during the course of treatment
are becoming possible. Consequently, in the fall of
2005,Varian Medical Systems launched a new initiative
emphasizing new Dynamic Adaptive Radiotherapy
(DART™) solutions.
DART is an emerging approach using up-to-date
image data to adapt a patient’s treatment based on
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Technology & Services
constantly evolving information about changes in
tumor shape, size, and position. Commenting on the
possibilities with DART Dow Wilson, president of
Varian’s Oncology Systems business, said,
“It is the next stage in personalized cancer care. It
means using technology to deliver the right dose to
the right place at the right time, every time, even
when the targeted tumor moves, shrinks, or changes
shape.The idea is to keep the treatment beam focused
on the tumor at all times, and do the best possible job
of protecting normal healthy tissues.”
The approaches to treatment using DART depend on
extremely tight integration between the component
parts of an IGRT system. Varian’s DART initiative is
based on Varian’s Inspiration™ platform, which
integrates advanced information management and
image-processing with rapid treatment planning and
advanced treatment delivery systems within a networked
clinical environment. It involves generating, accessing,
integrating, interpreting, and acting on new patient
information in realtime.
Varian is the only company delivering all the elements
needed to make DART clinically feasible. These
elements include:
• versatile X-ray imaging capabilities, including the
On-Board Imager device, with diagnostic quality
radiographic, fluoroscopic, and 3-D cone-beam
CT imaging;
• the SonArray™ 3-D ultrasound imaging and optical
technology for realtime tumor tracking;
• fully-automated, remote-controlled
positioning systems;
patient
• integrated data and image management tools.
Varian’s new ARIA™ oncology information system
(OIS) supports fully automated and rapid imageprocessing, so that clinicians can examine,
manipulate, and integrate image data from Varian’s
On-Board Imager device and use that data to adapt
their treatments;
• fast and automated treatment planning capabilities
with efficient plan re-optimization tools that can
make use of realtime image and dose distribution
information to refine a treatment plan quickly
and efficiently; and
• realtime motion management tools, including
fluoroscopic imaging capabilities and Varian’s RPM
respiratory gating system for imaging and treatment
in accordance with any respiratory motion;
Wilson continued to suggest:
“Varian’s DART initiative is putting numerous tools
into customers’ hands and coordinating them through
a fully integrated system, so that dynamic adaptation
can be accomplished using existing levels of staff,
within normal treatment time slots. We are moving
forward in our quest to make cancer a manageable
disease, and that means having the capacity to do
what is best for each individual patient in a clinically
practical and cost-effective manner. We believe that
dynamic adaptive radiotherapy is a major step in
that direction.” ■
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BUSINESS BRIEFING: US ONCOLOGY REVIEW 2006