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Release: April 3, 2001

UI uses ultrasound technology in complex surgeries

IOWA CITY, Iowa -- Radiation oncology specialists with University of Iowa Health Care recently performed the world's first ultrasound-guided extracranial radiosurgery.

Typically, computed tomography (CT) images are used to target tumors that are treated with radiation. The 3D images are transferred from the CT scanner to the radiosurgery device using reference marks on the patient. The patient is either moved from the CT scanner to the radiosurgery device, or the radiosurgery therapy may occur on a subsequent day. During the time between the CT scan and the actual treatment session, the patient will almost certainly be in a different position or the tumor itself may move as the internal anatomy shifts as a result of breathing and moving.

Using the ultrasound technology in the treatment room provides cancer specialists revised, up-to-date information about the precise location of the tumor inside the patient.

"The treatment plan from CT images guides the direction and the focus of the radiation beams and is meticulously outlined on the CT image in the hours or days before the radiosurgery procedure," said John Buatti, M.D., professor and director of radiation oncology in the UI Department of Radiology. "We can more accurately transfer the treatment plan into the treatment delivery room by using the ultrasound image to match the CT images used for the planning."

Even though the tumor may shift only slightly, perhaps five to 10 millimeters, the precision and accuracy of the state-of-the-art radiosurgery technology is enhanced by the addition of the ultrasound information. The extremely precise Linac scalpel directs radiation to within .2 millimeters for targets in the brain, and the ultrasound-guided technology should provide real-time targeting so that radiosurgery can be applied to lesions elsewhere in the body.

"This is an outstanding example of an innovative enhancement that combines the use of highly advanced imaging technology with the most advanced radiosurgery technology," said John Haller, Ph.D., adjunct assistant professor in the UI Department of Radiology. "We've been able to make radiosurgery available for lesions outside of the brain."

The Food and Drug Administration has approved this prototype ultrasound-guided radiosurgery system, which is being developed jointly by scientists and clinicians at the UI, including radiation oncologists, radiologists, otolaryngologists, and by neurosurgeons, physicians and scientists at the University of Florida and Zmed, Inc., based in San Diego, Calif.

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