New radiotherapy system benefits high-risk patients

Dec 10 2007

A new radiotherapy system that combines high-tech imaging with precision tumor-targeting capability is helping cancer specialists at Stony Brook University Medical Center treat patients.

Those with medically inoperable tumors, at high-risk for surgery, or who do not want surgical treatment may benefit most from the ExacTrac® X-ray 6D System for image-guided radiotherapy. The system adds to patient options for stereotactic body radiation therapy (SBRT), a technique that features high radiation doses with pinpoint precision to tumors.

Denis Keefe, 63, of Patchogue, N.Y., is a lung cancer patient who choose the image-guided radiotherapy system because it is the least invasive method available to treat his disease. Keefe was among the first patients to be treated with the system. The option was a good one for Keefe because his lung tumor was small and surgery remained risky because of his overall condition as a congestive heart failure patient.

“Other than mild redness, I experienced no side effects from the treatment and feel very good,” says Keefe, whose tumor has shrunk since the treatment. “I was comfortable during the procedure and only needed to go for three treatment sessions.”

Other patients have experienced few or no side effects when treated for lung cancer or other forms of disease with this radiotherapy system. The power and precision of the system also allows for short therapeutic duration. Treatments take one-to-two weeks to complete and require only three or four doses. Conventional beam therapy often lasts many weeks and many doses.

“We have had substantial success in treating patients with tumors of the lung, brain, spine, head and neck, and prostate with the ExacTrac system,” says Allen G. Meek, M.D., Chair of the Department of Radiation Oncology, indicating that the system has become an integral part of the department's therapeutic options after several months in operation.

“ExacTrac enables us to deliver treatment to some previously irradiated sites without damaging critical structures like the spinal cord,” explains Dr. Meek. “This greatly improves our ability to treat some inoperable tumors and cancers that spread from primary sites.”

“Scarring is considerably reduced with this new modality because it delivers top-of-the-line aiming capability using low dose beams from many directions that converge on the same target to deliver a high dose,” says Thomas Bilfinger, M.D., Professor of Surgery and Co-Director of the Lung Cancer Evaluation Center. “Less scarring leads to fewer losses of functioning tissue over time, which can be particularly beneficial for lung cancer patients.”

“The imaging component is critical to the process,” adds Bong S. Kim, M.D., Assistant Professor of Clinical Radiation Oncology. “We can position the patient within two millimeters precision, which maximizes radiation treatment directly to the tumor.”

The treatment procedure with the ExacTrac System consists of four major steps: 1) An automated and image-guided patient positioning system, based on the patient's form and location of tumor, is used for the initial patient set-up; 2) high-resolution X-rays pinpoint internal tumor sites, verifying the location across six dimensions and calculating key reference points for delivery of radiotherapy; 3) a remote control system corrects any initial patient set-up errors; and 4) the system tracks any patient movement that may affect treatment during the entire session.

For SBRT to be successful, optimal patient immobilization is required. The ExacTrac System uses the most advanced technology available for ensuring that the patient is positioned for treatment as accurately as possible. The computerized BodyFix® System guides the overall system by way of a non-invasive vacuum activated immobilization and fixation unit. This device limits movement caused by patient breathing, as well as tumor movement.

ExacTrac was purchased by SBUMC for nearly $600,000. Stony Brook is the only institution in Suffolk County, N.Y., to treat patients with this system. As imaging and computer technology continues to become more sophisticated, the system will mirror these advancing technologies in its precision delivery of radiotherapy.

http://www.stonybrook.edu/