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Stereotactic radiosurgery is used to quickly eradicate tumors by targeting them with high doses of radiation using precisely-shaped, image-guided, X-ray beams in just one to five treatment sessions. Varian's RapidArc, which targets treatment beams at tumors while rotating continuously around the patient, makes it possible to complete stereotactic radiosurgery sessions many times faster than conventional techniques that use stationary beams.
At VU University Medical Center in Amsterdam, doctors used a RapidArc-equipped linear accelerator from Varian to treat six patients with multiple brain metastases, delivering in a single plan a combination of whole brain radiotherapy with a stereotactic integrated boost, an extra measure of dose that is focused directly on the multiple tumors. "Our experiences to date have demonstrated that RapidArc appears to be excellent for stereotactic radiosurgery," says Dr. Frank Lagerwaardof VU Medical Center.
The patients, all of whom had developed multiple brain metastases stemming from primary lung or breast cancer, received their high-dose treatment over five sessions. "The total time needed for patients to enter and leave the treatment room has decreased to less than 15 minutes as we gain experience," adds Dr. Lagerwaard. "In these treatments the delivery' time was just 210 seconds per session." By comparison, conventional stereotactic treatment of three brain metastases using multiple dynamic conformal arcs takes more than 50 minutes from first beam on to last beam off, according to Dr. Lagerwaard.
At MIMA, Dr. Todd Scarbrough and his team treated a 77-year-old man with a history of small-cell lung cancer who had recently developed a brain metastasis."Given his smoking and lung cancer history he was not considered a candidate for conventional neurosurgery," says Dr. Scarbrough. "We felt fast, non-invasive radiosurgery would be easier on this patient."
Joseph Ting, PhD, medical physicist, compared a RapidArc radiosurgery treatment plan with a non-coplanar IMRT plan using 14 stationary beams, which is how this patient would have been treated prior to RapidArc's availability. "We were delighted to see that the RapidArc plan actually conformed the dose more closely to the size, shape and location of the tumor and could be delivered in three minutes instead of the 40 minutes needed for the 14-beam plan," Scarbrough said. The treatment was completed in four sessions over a four-day period.
Dr. Scarbrough adds, "Our plan is to use RapidArc any time the treatment plan gives us a dose distribution that is equal to or better than what we can get with standard IMRT, because RapidArc is so much faster. And that's much better for our patients."
In the August 15, 2008, issue of Clinical Cancer Research, (published online August 12) researchers from the University of Chicago Medical Center report that targeted radiation therapy had completely controlled all signs of cancer in 21 percent of patients who had five or fewer sites of metastatic disease.
Treatment planning analyses show that RapidArc matches or exceeds the precision of conventional IMRT systems and spares more of the healthy tissue surrounding the tumor. Unrelated clinical studies on radiotherapy correlate the ability to spare more healthy tissue with reduced complications and better outcomes.
Studies Revealed at AAPM
VU Medical Center's studies into the use of Varian RapidArc plans for brain metastases and other key tumor sites were showcased at this year's American Association of Physics in Medicine (AAPM) show in Houstonin July. Delivered using a Varian linear accelerator and measured in a solid water phantom, the 25 resulting film measurements showed high agreement with calculations, the VU team concluded. "RapidArc accurately delivers the planned dose distributions," stated Dr. Wilko Verbakel, medical physicist at VU Medical Center.
Dr. Ben Slotman, head of the radiation oncology department of VU University medical center said the hospital, among the first in Europe to introduce Varian's RapidArc, began clinical treatments using this fast and efficient form of volumetric modulated arc therapy in early May and more than 20 patients have so far been treated using the capability. "In the first few months we used RapidArc to replace IMRT treatments for head & neck, brain and prostate tumors but from September onwards RapidArc will replace all conventional IMRT," said Dr. Slotman. "Treatment planning is at least as good, and sometimes even better, than with conventional IMRT and planning and delivery using RapidArc is significantly faster."
Note to editors: Dr. Frank Lagerwaard will present his results at Varian's pre-ESTRO users' meeting in Gteborg, Sweden, on September 13th and Dr. Ben Slotman will appear at Varian's ESTRO Emerging Technologies symposium in Gteborg on September 16th to outline the clinical implementation of RapidArc at VU University medical center.
About Varian Medical Systems
Varian Medical Systems, Inc., of Palo Alto, California, is the world's leading manufacturer of medical devices and software for treating cancer and other medical conditions with radiotherapy, radiosurgery, proton therapy, and brachytherapy. The company supplies informatics software for managing comprehensive cancer clinics, radiotherapy centers and medical oncology practices. Varian is a premier supplier of tubes and digital detectors for X-ray imaging in medical, scientific, and industrial applications and also supplies X-ray imaging products for cargo screening and industrial inspection. Varian Medical Systems employs approximately 4,800 people who are located at manufacturing sites in North America and Europeand in its 60 sales and support offices around the world. For more information, visit http://www.varian.com/.
CONTACT: Neil Madle, Varian Medical Systems Tel: +44 (0)7786 526 068
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