RapidArc is up to eight times faster than conventional intensity-modulated radiation therapy
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Radiation oncologists at the University of Maryland Marlene and Stewart Greenebaum Cancer Center in Baltimore are now treating patients with a new technology called RapidArc that delivers radiation directly to a tumor two to eight times faster than conventional intensity-modulated radiation therapy, or IMRT.
University of Maryland physicist Cedric X. Yu, D.Sc., created the concept for the RapidArc technology and is working with the manufacturer, Varian Medical Systems, of Palo Alto, Calif., and other scientists in North America and Europe to develop new clinical applications for its use in treating cancer. The Marlene and Stewart Greenebaum Cancer Center is the first center in Maryland to offer the new technology.
RapidArc delivers radiation precisely to the tumor as the treatment machine moves around the patient in a single continuous 360-degree rotation. The treatment generally lasts two minutes or less. In conventional IMRT, treatments may take up to 15 or 20 minutes, as the machine makes several rotations around the patient, stopping and starting for beam adjustments.
“RapidArc is significantly faster than conventional IMRT, which means that patients don’t have to remain still for extended periods of time while they receive their treatment,” says William F. Regine, M.D., chief of radiation oncology at the University of Maryland Medical Center and professor and Isadore and Fannie Schneider Foxman chair of radiation oncology at the University of Maryland School of Medicine. “That means our patients are more comfortable, and we’re able to deliver more precise, targeted doses of radiation directly to the tumor because there is less chance that patients will move during treatment.”
RapidArc is made possible by recent technological advances that allow three parameters to be changed simultaneously during therapy: the rotation speed of the machine, the shape of the radiation beam and the rate at which the dose is delivered.
“With this new technology, we are able to deliver more intense radiation at certain angles to give the most powerful doses precisely where it’s needed without harming nearby tissue and organs. And we can do this in one continuous arc, which takes less time,” says Dr. Yu, a professor of radiation oncology at the University of Maryland School of Medicine.
He adds that for some cancers, there is a significant difference in treatment times between RapidArc and conventional IMRT. “For complex cancers of the head-and-neck area, which has a number of vital structures, treatment can typically take more than 20 minutes with IMRT, compared to two to three minutes with RapidArc.”
RapidArc is delivered using the cancer center’s Trilogy linear accelerator, an image-guided radiation therapy system that can deliver all forms of external-beam radiation therapy, including conventional radiation treatment, IMRT, image-guided radiotherapy (IGRT) and stereotactic body radiotherapy (SBRT). Trilogy has a built-in imaging system that can pinpoint the size and location of a patient’s tumor movements before each treatment.
Radiation oncologists at the Greenebaum Cancer Center initially used the RapidArc technology to treat prostate cancer, but are now using it for other cancers, including head-and-neck cancers.
RapidArc is a form of intensity-modulated arc therapy (IMAT), which Dr. Yu invented in 1995. Since he has been at the University of Maryland, Dr. Yu and his colleagues in the Department of Radiation Oncology have been involved in other research that has led to a number of important advances in the field of radiation oncology. These include innovations such as direct aperture optimization (DAO), which is a better method for planning IMRT treatments, and improved methods for managing breathing-induced tumor movements during radiation treatments.
Because of the strength and reputation of the radiation oncology program, the University of Maryland Greenebaum Cancer Center is one of four centers in the country to have signed a master research agreement with Varian Medical Systems, a world leader in radiation technology development, to devise new radiation technologies. The Greenebaum Cancer Center, a National Cancer Institute-designated center, offers innovative approaches to diagnosing and treating all types of cancer, serving patients throughout Maryland and the Mid-Atlantic region.
For more information about RapidArc or the radiation oncology program at the cancer center, go to: http://www.umgcc.org/radiation_oncology_program/index.htm.