BOSTON, Sept. 24 /PRNewswire-FirstCall/ -- Cancer treatment specialists reported yesterday how new technologies are enabling them to provide faster, more accurate cancer treatments than was possible with earlier generations of radiotherapy technology. In presentations given at an "Emerging Technologies" Symposium sponsored by Varian Medical Systems (NYSE: VAR) in connection with the annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO), doctors detailed how they are using RapidArc™ radiotherapy technology, as well as cone-beam CT (3-D) imaging to offer their patients highly-accurate and more comfortable cancer treatments.
The symposium presentations began with Clif Ling, PhD, a renowned expert in the fields of medical physics and radiation oncology. In his talk entitled "Affirming the past -- anticipating the future -- comments during the 50th Anniversary of ASTRO" he provided a history of the technological advances, many of which were provided by Varian, that have led to improved clinical outcomes and increased survival among cancer patients treated with radiotherapy. According to Ling, the technical advances in radiation oncology can be summarized in four categories:
1) Improvements in imaging, which made it possible to see a tumor and its surrounding normal tissues, and to create treatment plans based on a patient's unique anatomy. 2) Advances in the design and optimization of treatment plans, thanks to computer algorithms that work with volumetric (3-D) CT image data to calculate an optimal way of delivering the desired radiation dose in three dimensions. 3) Improvements to treatment delivery systems, including sophisticated multileaf collimators that continually shape the radiation beam so it matches the shape and size of the tumor from all angles. 4) Greater understanding of the clinical radiobiology of radiotherapy, an effort that continues and that is leading to new studies in the "uncharted waters" of stereotactic radiotherapy and radiosurgery, involving very high dose treatments delivered in just one to five treatment sessions. The Promise of RapidArc
Using Varian's RapidArc radiotherapy technology in the treatment of brain tumors, Ben Slotman, who is professor and chairman of the Department of Radiation Oncology at the VU University Medical Center in Amsterdam, Netherlands, said he was able to shorten his treatment protocols by an hour or more per patient. Slotman delivered whole-brain radiotherapy plus an integrated stereotactic boost in five sessions that took fifteen minutes per day from start to finish (including imaging, patient positioning, and treatment). "The main benefit to integrating the stereotactic boost by using RapidArc is the fact that the patient does not have to lie still for an additional 60-90 minutes," Slotman said.
"The delivery of a RapidArc treatment is very fast, which has important clinical implications," he added. "Treatment times are much shorter, so there is less chance that a patient will move during treatment, which helps to ensure accurate targeting. Another clear benefit is that it is more comfortable for patients and more patients can be treated in a single day," he said.
Slotman and his colleagues compared RapidArc treatment plans with plans for conventional IMRT. The RapidArc plans were faster to create, he said, and they produced equal or better dose distributions with superior protection of surrounding healthy tissues.
Advances in Image-Guided Radiosurgery with the Novalis Tx Platform
Three-dimensional cone-beam CT imaging is enabling Benjamin Movsas, MD, to offer his patients image-guided stereotactic radiotherapy and radiosurgery treatments without the invasive process of planting fiducial markers, such as gold seeds, into the tumors. Using the On-Board Imager™ device on a new Novalis Tx™ treatment platform, Movsas and his clinical team can generate 3-D images that show soft tissue structures, such as the tumor and surrounding organs, making fiducial markers unnecessary.
"It's often not possible to place fiducial markers into lung tumors without risking the possibility of a collapsed lung or other injury," said Movsas, who is chairman of the Department of Radiation Oncology at Henry Ford Hospital in Detroit. "Even when fiducials can be safely used, a cone-beam CT image is still critical because it shows us key information about the tumor itself, like changes in the tumor volume or shape over time."
In addition to the On-Board Imager, the Novalis Tx platform at Henry Ford Hospital in Detroit incorporates ExacTrak® room-based X-ray imaging system, and having both offers some key advantages, Movsas said. "While cone-beam CT can provide us with in depth data about the targeted tumor, ExacTrak can be used strategically, to take a "snap shot," even during treatment, for a rapid verification that the tumor is still in the correct position."
Movsas, also spoke of the sophisticated stereotactic body radiosurgery (SBRT) work that has been taking place at Henry Ford for some time, using earlier generations of linear accelerators from Varian and BrainLAB. Henry Ford clinicians have treated thousands of patients with focused stereotactic radiosurgery, and they have become known for their pioneering clinical work treating tumors of the spine. The new Novalis Tx is being used to build on this expertise, and to help create a more fully integrated multidisciplinary stereotactic radiosurgery program.
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 Europe and approximately 60 sales and support offices around the world. For more information, visit http://www.varian.com/.
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