"Non-coplanar beams can be particularly useful, for example, when treating brain tumors that lie in the same plane as the eyes," explains Corey Zankowski, senior director for oncology product management. "By rotating the couch during treatment to deliver arcs from different angles, clinicians can greatly minimize any exposure of the eyes and still achieve an excellent dose distribution within the targeted tumor."
Joseph Ting, chief medical physicist at the MIMA Cancer Center in Melbourne, Florida, elaborates: "We'll see a big benefit in treating certain head and neck cancer cases, particularly when the tumor is low in the neck area, so that a conventional arc would pass through the shoulder area. You can reduce the amount of normal tissue exposed to the beam by choosing several arcs that enter away from the shoulder," he said.
According to Ting, use of multiple arcs in different planes also allows doctors to spread out the peripheral dose more widely, so that surrounding normal tissues receive much less radiation. "Normal tissue tolerances for low levels of radiation are pretty well known," Ting said. "By spreading the peripheral dose out over a greater volume of tissue, we can keep the level very, very low in any given area, particularly when treating with high-dose stereotactic radiosurgery."
Using several arcs also makes it possible to treat multiple tumors simultaneously. For example, when two or more tumors in the brain lie in front of one another, they can be accurately targeted with a single treatment that devotes an arc to each.
"This new version of RapidArc is part of our commitment to the
continual development of versatile, uncompromising solutions for targeting
cancer and minimizing undesirable side effects," says Knott. "With these
enhancements, we are providing doctors with more angles of approach to use
when targeting diseased tissue, and more degrees of freedom to optimize the
|SOURCE Varian Medical Systems, Inc.|
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