The 45th Annual Meeting of the American Society of Therapeutic Radiology & Oncology (ASTRO) was held October 19 to 23, 2003 in Salt Lake City, UT. Several new technologies for the treatment of cancer were displayed at that conference.
Patients often report persistent neck pain following traumatic
injury, despite negative findings on magnetic resonance imaging
(MRI) studies. In such cases, X-rays taken in flexion/extension may
show a disc lesion; but MRI, which is performed with the neck in a
neutral position, often does not reveal any abnormality.
Steven L. Rhodes, DCM, a chiropractor from Jacksonville, FL, has
worked to prevent this disparity. This came about after I had a
patient with a negative MRI scan, yet I knew something was wrong
with her, Rhodes explained. On a flexion/extension X-ray, I could
see malposition of the vertebra. But in that same patient with her
head in a neutral position, the vertebra looked OK. I thought that
might be what had happened with her MRI scan.
I asked the staff of an MRI unit to put a patient in
flexion/extension so I could duplicate what I was seeing on the
X-ray. But they couldn't do it, he continued. He found that using
props or wedges didn't work. For instance, if you place a round
pillow under the patient's neck to put him/her in extension while
in the MRI tube laying on the back, biomechanically, that round
pillow supports all the vertebrae in the curve and you lose the
effect that you get with the patient standing up with their head
To address this need, Rhodes developed a flexion/extension
device for MR imaging, the Rhodes Patented Flexion/Extension Coil,
which allows MR studies to be performed with the neck in
flexion/extension (Figure 1).
I had to design it in such a way that the neck coil on the MRI
unit could get around the patient and still drop into the recess in
the device to allow the same movement of the vertebrae, he
explained. With engineering work, we got it to work on almost all
open MRI scanners. We have also custom made one to fit a closed
scanner, which requires a different set of mechanics.
Researchers from a local neuroscience institute saw some of the
images and called me to find out how to get them done, Rhodes
continued. After evaluating roughly 100 scans, one of the
neurologists conducted an independent study and found that in 40%
of patients they found disc lesions when using the device that
weren't seen with the patient's head in a neutral position.
[Griffiths HJ, Rhodes S, Kidwai A. Radiologic case study.
I primarily invented it to help diagnose disc and
anterior-posterior longitudinal ligament injury; and it reveals an
abundance of injuries that may not be seen with a person lying
flat, said Rhodes.
Some patients had been told that their pain was in their heads
since their scans were negative. The nurse on whom I did the first
scan was having severe headaches, neck pain, and numbness in her
arm; yet she had a negative MRI. She thought she was going
As an expert witness in personal injury cases, it's also very
important to have a diagnostic study to document and validate where
the injury is, otherwise the court will ignore it.
A prospective 1000-case study on the device is planned at the
University of Florida in Jacksonville. Each participant will
undergo MRI with and without the use of the device.
The device has been FDA-registered and is available through a
national distributor, Contour Fabricators, Inc. (Fenton, MI). The
standard device fits approximately 90% of available open MRI units,
and custom-designed devices can be created to fit high-field closed
News from ASTRO
The 45th Annual Meeting of the American Society of Therapeutic
Radiology & Oncology (ASTRO) was held October 19 to 23, 2003 in
Salt Lake City, UT. Several new technologies for the treatment of
cancer were displayed at that conference.
New multislice CT for radiation therapy planning
GE Medical Systems (Waukesha, WI), in conjunction with Varian
Medical Systems, Inc. (Palo Alto, CA), unveiled a new 4-slice
computed tomography (CT) system designed specifically for radiation
therapy planning, the GE LightSpeed RT.
In working closely with clinicians during the development of the
LightSpeed RT, we learned that oncologists needed a complete
oncology imaging system, not just a wide-bore scanner, said Peter
Arduini, General Manager, Global CT at GE. By combining a
multislice, wide-bore, wide field-of-view CT scanner with advanced
oncology applications and a powerful productivity workflow engine,
we provide the total package.
On the LightSpeed RT, we have simulated many patients for breast
irradiation who were comfortably positioned on the breast angle
boards set at 15š and 20š, noted Jay Harris MD, Chair and
Professor, Radiation Oncology at the Dana-Farber/Brigham and
Women's Cancer Center (Boston, MA). We are now able to scan
patients in a frog-legged position for pelvic sites, as well as
accommodate mantle patients in the treatment geometry with greater
ease. The large 65-cm display field-of-view offers visualization of
peripheral anatomic details that are essential for treatment
planning, but would have been lost on conventional 50-cm display
The system can be used in conjunction with several advanced
applications including GE's Advantage 4D respiratory gating
software for tumor and organ motion assessment and margin
localization. This application incorporates Varian's RPM
Respiratory Gating device.
Advantage 4D makes it possible to acquire CT scans that capture
the motion of tumors and adjacent critical structures, said George
T.Y. Chen, PhD, Professor of Radiation Therapy at Massachusetts
General Hospital, Boston, MA. It is a quantum leap for radiation
planning in the presence of motion, because it provides a more
accurate description of the target and its trajectory. This
provides information essential in designing treatment margins and
sparing normal tissues.
New image-guided radiation therapy system
Varian Medical Systems also previewed their new image-guided
radiation therapy system designed to work with both conventional
and stereotactic approaches. The Trilogy system is pending 510(k)
clearance from the FDA.
The system can be used to deliver 3D conformal radiotherapy,
intensity-modulated radiation therapy (IMRT), stereotactic
radiosurgery, fractionated stereotactic radiation therapy, and
intensity-modulated radiosurgery for cancer and neurosurgical
Trilogy is the first system for delivering all forms of
external-beam radiation therapy, said Timothy E. Guertin, President
of Varian's Oncology Systems business. It will enable doctors to
choose the most appropriate treatment modality for treating cancer
in the body or the head and neck, and to deliver the full spectrum
of treatments, all on one machine in a single room.
The new system is based on the company's 23EX Clinac linear
accelerator, which has been enhanced for stereotactic applications
by increasing its maximum dose delivery rate from 600 to 1000
monitor units per minute and by fine tuning the isocenter to a 1-mm
diameter sphere. In addition, the treatment couch can be moved via
remote control, thereby speeding treatment and maximizing the
number of available beam angles.
With Trilogy, doctors have the option to treat some small
lesions using stereotactic radiosurgery, delivered in a single
treatment, or stereotactic radiotherapy, delivered over a period of
days. It can also be used for conventional and conformal radiation
therapy, delivered in daily small doses over a period of weeks.
In the future, we envision equipping Trilogy with imaging
technology that will give doctors radiographic (two-dimensional),
fluoroscopic (time-lapse), and cone-beam CT (three-dimensional)
images for even more precise patient positioning and tumor
localization, concluded Guertin.