Doctors at Emory University's Winship Cancer Institute recently began treating patients with a new, more precise radiation delivery system that offers an alternative to the surgical removal of brain tumors. In addition, doctors are using the new equipment to attack primary lung cancers, liver and pancreatic cancers and bone metastases, says Ian Crocker, MD, professor of radiation oncology at Emory University School of Medicine. Emory is one of the first medical centers in the world to offer treatment with the Novalis Tx, made by Varian Medical Systems. One of the added features of the Novalis Tx is a high-definition multileaf collimator, a device that shapes the X-ray beam with rows of tungsten metal "leaves" whose position can be minutely adjusted. The new equipment improves resolution by a factor of two over earlier technology by reducing the width of the leaves.
In 2004, Emory was the first site in the world to offer treatment with Novalis Tx's predecessor, the Trilogy. "With the new equipment, the additional precision means we can target smaller tumors and limit damage to nearby tissues," Crocker says.
Now, doctors at Emory can offer patients a variety of options based on their needs, ranging from radiosurgery, a very fast treatment designed to eradicate smaller tumors in a single session, to lower-dose treatments spread out over more sessions. "In certain situations, we consider the single-session intense radiation treatment as a preferable alternative to surgery or when surgery is not feasible," Crocker says. "An example is when a tumor is deep within the brain and surgery risks damaging critical structures in getting to the tumor."
"The advantage here is that the patient can come in for approximately 45 minutes, compared with a traditional course of radiation therapy that might take several weeks," Crocker says.
Other conditions that encourage use of radiosurgery include when conventional surgery would interrupt a patient's chemotherapy schedule, or when a patient may be unable to tolerate anesthesia, he adds. The radiation treatment works by damaging the DNA in tumor cells. It typically halts the growth of tumors and in some cases will cause them to disappear. Before initiating treatment with this new machine, Emory physicists had an independent laboratory verify the accuracy of radiation delivery. The Novalis Tx incorporates a rotating linear accelerator, the high definition collimator and on-board imager with which physicians can perform X-rays or CT (computed tomography) scans to check the location of the tumor immediately before radiation delivery.