Real-Time Visualization of Tumors Leads to More Precise Radiation Treatment

PHILADELPHIA - Imagine a technology that would allow your doctor to see your tumor in three dimensions so that radiation treatment is targeted precisely. And imagine that significant side effects from treatment become the exception. That hope is the promise of a new technology called at Fox Chase Cancer Center called Trilogy(tm).

"People move so of course tumors move," says Alan Pollack, M.D., Ph.D., chairman of radiation oncology at Fox Chase. "Locating the tumor right at the time of treatment gives us an unprecedented advantage. This is especially important when treating lung and liver tumors, which move with breathing."

Fox Chase has been a leader in research on 3-D-image-guided radiation therapy, treating more patients with such methods over the years than any other cancer center in the region. The new Trilogy linear accelerator system represents the newest and most powerful technology available for combining image-guidance with the latest radiation delivery methods.

Trilogy combines a linear accelerator (the machine that delivers radiation) with an on-board imager to check a patient's position and improve the targeting of radiation to the tumor to achieve the precision needed for stereotactic radiosurgery.

The versatile Trilogy system can be used to deliver intensity modulated radiation therapy (IMRT), 3-D conformal radiotherapy, stereotactic radiosurgery (high radiation doses in a single treatment), fractionated stereotactic radiation therapy (high radiation doses over a few days), and intensity-modulated radiosurgery for cancer.

Stereotactic techniques involve delivering extremely high doses of radiation to very small areas over a shorter period of time, as compared to conventional external-beam radiation therapy. The technologies are linked through a sophisticated computer system that adjusts the aim of radiation with the patient's external contours and daily changes in the patient's internal organ positions.

"This is an advance that will benefit certain patients immediately by allowing us more options and more precision," explains Pollack. "Trilogy marries imaging technologies with the computer system programmed to deliver radiation. These systems work together to target the tumor precisely at the time of treatment.

"It's another leap forward in technological capability. Trilogy allows us to deliver all types of external-beam radiation therapy using one machine in a single room."

Trilogy's major capability involves image-guided radiosurgery (IGRS) technology. With IGRS, doctors can target tumors with high doses of radiation. IGRS is particular effective in treating patients with tumors that have spread (metastasized) to the brain, spine, lung and liver. Treatment of these areas must be extremely exact. Patients recover rapidly from radiosurgery because there are no incisions and the radiation is so focused.

In addition to allowing physicians to accurately locate the tumor, Trilogy's optical system continuously monitors the patient to ensure the patient remains properly positioned during treatment. The delivery system adjusts to the patient's movement. Trilogy is able to synchronize a patients breathing with the radiation delivery.

"For treatment planning, we are combining the Trilogy radiation delivery systems with the most advanced 4-D CT-simulation and MRI-simulation methods available," explains Pollack. "Fox Chase has been a leader in applying these sophisticated planning techniques. They provide a unique visualization of tumor motion during treatment so that adjustments in targeting or 'gating' the radiation beam on and off at different points in the respiration cycle are planned into the treatment delivery process."

Fox Chase Cancer Center was founded in 1904 in Philadelphia as the nation's first cancer hospital. In 1974, Fox Chase became one of the first institutions designated as a National Cancer Institute Comprehensive Cancer Center. Fox Chase conducts basic, clinical, population and translational research; programs of prevention, detection and treatment of cancer; and community outreach. For more information about Fox Chase activities, visit the Center's web site at www.fccc.edu or call 1-888-FOX CHASE.

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