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"Last year at this time, we introduced RapidArc, which delivers ahighly-precise volumetric IMRT treatment in less than two minutes with asingle arc, or rotation, of the treatment machine around the patient," saidKarla Knott, Varian's senior director of marketing. "This year we are showinga new version that makes RapidArc even more powerful and versatile fortreating a broader spectrum of indications."
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The enhanced version of RapidArc enables more versatile approaches fortargeting large, irregularly shaped, or awkwardly-positioned tumors. Itincorporates tools for planning and delivering IMRT treatments using one ormore arcs, or multiple non-coplanar arcs, which are typically used forstereotactic radiosurgery.
RapidArc also now features the "skip" arc, which turns the beam off duringsome portion of a rotation, to completely avoid some parts of the patient'sanatomy. With these new features, clinicians have more options for sculptingdose distributions to protect healthy tissues.
"Non-coplanar beams can be particularly useful, for example, when treatingbrain tumors that lie in the same plane as the eyes," explains CoreyZankowski, senior director for oncology product management. "By rotating thecouch during treatment to deliver arcs from different angles, clinicians cangreatly minimize any exposure of the eyes and still achieve an excellent dosedistribution within the targeted tumor."
Joseph Ting, chief medical physicist at the MIMA Cancer Center inMelbourne, Florida, elaborates: "We'll see a big benefit in treating certainhead and neck cancer cases, particularly when the tumor is low in the neckarea, so that a conventional arc would pass through the shoulder area. Youcan reduce the amount of normal tissue exposed to the beam by choosing severalarcs that enter away from the shoulder," he said.
According to Ting, use of multiple arcs in different planes also allowsdoctors to spread out the peripheral dose more widely, so that surroundingnormal tissues receive much less radiation. "Normal tissue tolerances for lowlevels of radiation are pretty well known," Ting said. "By spreading theperipheral dose out over a greater volume of tissue, we can keep the levelvery, very low in any given area, particularly when treating with high-dosestereotactic radiosurgery."
Using several arcs also makes it possible to treat multiple tumorssimultaneously. For example, when two or more tumors in the brain lie infront of one another, they can be accurately targeted with a single treatmentthat devotes an arc to each.
"This new version of RapidArc is part of our commitment to the continualdevelopment of versatile, uncompromising solutions for targeting cancer andminimizing undesirable side effects," says Knott. "With these enhancements,we are providing doctors with more angles of approach to use when targetingdiseased tissue, and more degrees of freedom to optimize the treatment foreach and every patient."
ABOUT VARIAN MEDICAL SYSTEMS
Varian Medical Systems, Inc., of Palo Alto, California, is the world'sleading manufacturer of medical devices and software for treating cancer andother medical conditions with radiotherapy, radiosurgery, proton therapy, andbrachytherapy. The company supplies informatics software for managingcomprehensive cancer clinics, radiot
