Doctors at UT Southwestern Medical Center at Dallas and Zale Lipshy
University Hospital are using an experimental radiation therapy
device to treat brain cancer patients for whom conventional radiation
treatments have not been effective.
Dr. Dan Garwood, assistant professor of radiation oncology, has
treated 12 patients with the Accuray robotic device during the past 9
months. Because many patients had tumors in several areas of the
brain, 29 separate tumors were irradiated. UT Southwestern is one of
only five sites in the United States testing the apparatus, developed
by Accuray, Inc., of Sunnyvale, California. Other sites include
Stanford University; Shadyside Hospital of Newport Beach, California;
The Cleveland Clinic; and a facility in Pittsburgh, Pensylvania.
In Dallas, the generosity of local philanthropists, who contributed a
total of $2.8 million, made it possible for UT Southwestern to obtain
the state-of-the-art cancer-fighting tool.
Greater Precision and Flexibility
This instrument is particularly useful for treating brain cancer
because of the precision and flexibility of the system (Figures 1
and 2). The key to effective
radiation therapy in these situations is to put more treatment into
the tumor and less into the surrounding normal tissue, said
Garwood, holder of the Effie Marie Cain Distinguished Chair in Cancer
Therapy Research. The strength of the Accuray treatment is its
ability to target many beams of radiation more precisely.
The Accuray device is designed to give clinicians much greater
control over the beams of radiation that kill the tumor. A miniature
linear accelerator, weighing only about 300 pounds and mounted on a
robotic arm, can direct approximately 100 different beams of x-rays
to a tumor from many angles.
The robotic arm allows the patient to stay in one position as the
linear accelerator moves around to deliver treatment. A set of
x-ray-imaging cameras that are part of the instrument enables
physicians to see a tumor as it is treated.
A highly sophisticated computer program generates a three-dimensional
image that reveals a tumors precise location, shape, and size.
Radiation oncologists use the computer to calculate the position and
intensity of the individual beams that target the cancer, thus
avoiding delivery of radiation to the surrounding normal tissue.
As a final step before treating a patient, a Lucite model of the
persons head, including a removable block representing the
tumor, is built. The treatment program is tested on the model, and
the accuracy of the radiation beams is determined using film inserted
in the Lucite tumor.
Only Selected Patients Eligible for Treatment
Treatment using the Accuray is still experimental and limited by US
law to investigational use. Only patients who have certain kinds of
malignant brain tumors and have undergone unsuccessful conventional
treatment are currently eligible for treatment with the new device.
For more information, call (214) 648-7684.