Varian, GE develop fusion imaging process

Varian Medical Systems and GE Medical Systems have joined forces in a venture that combines functional and anatomical imaging with intensity-modulated radiation therapy (IMRT) to more effectively and efficiently plan therapy, according to company officials.

The process enables physicians to pinpoint and eradicate tumors with minimal destruction of the healthy tissue surrounding targeted lesions, company spokespersons said. It has shown promise in diagnosing and treating prostate, breast, and head and neck cancers, among others.

"The essence is being able to take functional imaging and fuse or meld that with anatomical imaging, then sculpting the dose distribution to those highly localized target volumes using IMRT," said Calvin Huntzinger, product marketing manager for Varian. "This could influence a number of treatments. It's not an enhancement to an existing modality."

The process, dubbed "See and Treat Cancer Care," arose out of a four-year agreement the two companies announced in January. The alliance called for Varian and GE to develop a package of medical imaging and radiation therapy systems aimed at treating cancer.

See and Treat Cancer Care involves the use of GE imaging technologies, including CT and MRI, to locate tumors within patient anatomy. Also involved are magnetic resonance spectroscopy (MRS), PET, and single-photon emission computed tomography (SPECT), which provide metabolic data on a tumor's location, size, and aggressiveness.

Clinicians collect and combine data from each of the modalities' images, fusing them to develop optimal plans for radiation therapy. GE imaging data are transmitted to Varian treatment systems using standard medical electronic information interfaces.

Initially, patients are imaged using the GE Millennium VG Hawkeye, which combines CT and nuclear medicine systems. The device enables physicians to take a variety of anatomical and functional images concurrently, fusing them by means of 3-D software designed to locate and evaluate tumors. The FDA granted premarket approval for the Hawkeye earlier this year.

An IMRT delivery technique is developed on the basis of those images, and the patient is treated using a linear accelerator. Treatment usually occurs a day or two after the anatomical and functional images are taken, Huntzinger said.

"This process reduces the dose to the healthy tissue," Huntzinger said. "Cases that in the past involved more treatment of normal tissue and a higher degree of side effects can now be treated with greater accuracy and less destruction."

The key to the process is the addition of functional images to the structural imaging process, he said.

Although IMRT is not new, fusion imaging has drawn considerable attention in recent months. Of the hundreds of scientific papers presented during the Society of Nuclear Medicine meeting in June, 41 dealt with some aspect of fusion imaging (SCAN, 6/21/00).

In September, SMV's Positrace, the first commercially available PET/CT system, obtained 510(k) clearance from the FDA. The clearance for GE's Hawkeye applied only to SPECT/CT, although clinical trials for PET/CT are under way.

Although still new, the strategic alliance of GE and Varian appears to be a logical one. GE is a longtime leader in medical technology, while Varian is a leading manufacturer of integrated cancer therapy systems. Varian also is a top supplier of x-ray tubes and flat-panel digital subsystems for medical, scientific, and industrial applications.