LOS ANGELES, Oct. 31 Two noted cancer treatmentspecialists reported yesterday about how they are using technologies fromVarian Medical Systems (NYSE: VAR) to target tumors more accurately and tospeed up delivery of ultra-precise intensity-modulated radiotherapy (IMRT)treatments. An expert from the BC Cancer Agency in British Columbia presentedan approach to volumetric arc radiotherapy, which makes it possible to deliveran IMRT treatment up to eight times faster than is possible with conventionaltreatment approaches. And an expert from Stanford University discussed novelimage-guided motion management techniques for accurately treating lung cancerand other tumors that move during treatment as the patient breathes. Thepresentations were part of an "Emerging Technologies Symposium" sponsored byVarian in connection with the annual meeting here of the American Society forTherapeutic Radiology and Oncology (ASTRO).
Using Volumetric Modulated Arc Therapy at the BC Cancer Agency
W. James Morris, MD, associate professor at the University of BritishColumbia and radiation oncologist with the BC Cancer Agency, presented anapproach to volumetric arc therapy (VMAT) that has been developed and used athis agency to deliver an ultra-precise IMRT treatment for prostate cancer inless than two minutes. This type of treatment normally would take at leastten minutes to deliver. A VMAT treatment is faster because it delivers a fulldose to the entire targeted tumor volume with just a single rotation of thetreatment machine around the patient.
"The treatments are delivered with high levels of dosimetric accuracy,"Morris said. "The dose distributions with VMAT are equal or better to theones you can get using conventional IMRT delivery techniques, and much fasterto deliver."
Motion Management in the Thorax
Billy W. Loo, Jr., M.D., Ph.D. of Stanford University, Palo Alto,California, described how his team uses 4D CT scans, which are images thatcorrespond with particular phases of the patient's respiratory cycle, tocreate a respiratory gating strategy for triggering the treatment beam on andoff in timed bursts that are synchronized with the patient's breathing. Priorto each treatment, Loo's team verifies that the programmed respiratory gatingstrategy is still valid by studying fluoroscopic (moving) and cone-beam CT(volumetric) images of the targeted area and surrounding anatomy, generatedusing Varian's On-Board Imager(R) device.
"Near-real-time image guidance tools are the wave of the future, becausethey will enable us to be much more accurate in how we address motion andreduce treatment margins to spare more healthy tissue," Loo said.
Varian's RapidArc(TM) Radiotherapy Technology
Varian CEO Tim Guertin introduced Varian's new RapidArc(TM) radiotherapy*,the company's new VMAT technology that will enable clinicians to deliverhighly-conformal treatments much faster than is possible with conventional orhelical IMRT (tomotherapy). Guertin said that Varian's goal is "to reduce theamount of time it takes to deliver these treatments -- the best available --to less than five minutes. Two minutes to set the patient up for treatment,and two to treat -- that's where we're headed," he said. "Faster imaging andfaster treatment, with no sacrifice in terms of accuracy or precision, aregoing to be the cornerstones of effective, affordable cancer care."
*RapidArc is pending FDA 510(k) clearance, and not yet available for salein the U.S.
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, radiotherapy centers and medi