Image Guidance Radiotherapy Improving the Treatment of Lung Cancer

Loo, Jr., M.D., assistant professor of radiation oncology at Stanford University (Palo Alto, CA, USA). Dr. Loo was one of three preeminent experts who made presentations at a special symposium for Chinese radiation oncology professionals sponsored by Varian Medical Systems, Inc. (Palo Alto, CA, USA) and held in connection with the 2nd Chinese Society of Therapeutic Radiology and Oncology and Sino-American Network for Therapeutic Radiology and Oncology (CSTRO/SANTRO) joint meeting in Hangzhou, China, in October 2010.

"Early stage cases, and especially those patients who are unfit for surgery, can be effectively treated using stereotactic ablative radiotherapy [SABR], a very fast, image-guided, arc-based approach,” said Dr. Loo. "Varian's technologies for this type of treatment--the Trilogy and TrueBeam systems for image-guided radiotherapy--are an attractive way to deliver SABR.”

SABR, which is also referred to as stereotactic body radiotherapy (SBRT), involves the use of highly focused radiation concentrated on small tumors that have been discovered early, so it depends on early detection, said Dr. Loo, who uses Varian's Trilogy and TrueBeam systems to deliver these advanced treatments. "A large dose is given in one or just a few treatment sessions. Dose delivery is extremely accurate and precise, due to image-guidance, patient immobilization, and other technologies designed to ensure accuracy,” he added.

Dr. Loo noted that studies conducted by researchers worldwide have shown that SABR produces better tumor control rates, and higher overall survival rates, than conventional radiotherapy. To deliver SABR treatments at Stanford, Dr. Loo and his colleagues depend on the full range of capabilities available to them with their Trilogy and TrueBeam systems, including fluoroscopic imaging for determining the extent of tumor motion, cone-beam computed tomography (CT) imaging for pretreatment patient positioning, respiratory gating for motion management, high dose delivery rates for efficiency, and RapidArc to attack the tumor from all angles in a 360^o arc. "SABR for early stage lung cancer is rapidly maturing, with promising early results,” Dr. Loo concluded.

Another presentation, by Maria Chan, Ph.D., from Memorial Sloan Kettering Cancer Center (New York, NY, USA), focused on the use of Varian's On-Board Imager device to perform IGRT. The On-Board Imager is a standard component of Varian's high-energy linear accelerators for the treatment of cancer. It is used to generate radiographic (2-D), cone-beam, three-dimensional (3D) CT or fluoroscopic images that show how a tumor moves as a patient breathes in and out. These images make it possible to accurately pinpoint the tumor and adjust the patient's position just prior to each treatment.

A third presenter, Christopher Willett, M.D., of Duke University (Durham, NC, USA), discussed his clinical team's use of RapidArc technology to deliver precise image-guided treatments rapidly by delivering the dose continuously from 360^o around the patient while shaping the treatment beam to match the shape of the tumor from every angle. RapidArc makes it possible to complete an image-guided treatment two to eight times faster than is possible with conventional approaches to beam delivery.

"Varian Medical Systems has a corporate mission of helping radiation oncology professionals to save another 100,000 lives every year,” said Thomas P. Duffy, Varian's vice president of sales and marketing for the Asia Pacific region. "To that end, we are committed to supporting the clinical adoption of advanced forms of radiotherapy across China. We sponsored this symposium as part of our commitment to facilitating the transfer of best clinical practices between the east and the west.”

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Stanford University
Varian Medial Systems
Memorial Sloan Kettering Cancer Center
Duke University