Varian's 'respiratory gated' cancer treatment used on first lung cancer patient

By E. Janene Geiss

Philadelphia, Feb. 21 - Varian Medical Systems, Inc. said Tuesday that a 65-year-old German man has become one of the first lung cancer patients in Europe to be treated with radiation therapy that is delivered in timed bursts to take account of tumor movement caused by breathing.

His "respiratory gated" treatment has been carried out at the Klinikum Cancer Center in Dortmund, Germany, using a unique monitoring system developed by Varian that tracks and coordinates treatment delivery with patients' natural breathing patterns, according to a company news release.

Using the Varian RPM Respiratory Gating system, doctors at Klinikum have been able to improve the treatment by boosting doses for the patient while sparing more of the healthy tissue surrounding his lung tumor, officials said.

This approach enabled doctors to concentrate more dosage on the tumor while reducing exposure of the surrounding healthy tissue by up to 22%.

"There's no doubt that this approach enables you to better protect normal tissue, increase patient comfort and have fewer side effects," Oliver Waletzko, head of radiation oncology at Klinikum, said in the release. "Because of this, we can safely boost doses to the tumor and have more effective treatments, all within a standard treatment time."

Respiratory gating is used regularly for left-sided breast cancer patients who have previously received cardiotoxic chemotherapy as a method of reducing the volume of the heart exposed to radiation, but it is much rarer for lung patients, officials said.

Unlike an active breath-hold technique in which patients are forced to hold his or her breath during treatment - Varian's RPM system offers faster and more comfortable treatments by making it possible to deliver bursts of radiation that coincide with a patient's natural breathing cycle. It is well suited for lung cancer patients who often have great difficulty in holding their breath, even for short periods, officials said.

Doctors at Klinikum use a Varian Acuity simulation system to set up the patient for treatment and a 4D 8-slice GE scanner for imaging. The clinic has just acquired the second 64-slice scanner in Germany and will soon upgrade it to become among the first 4D 64-slice scanners in the world. This will enable them to further boost doses and extend their gating program to include abdominal tumors, officials said.

Varian said it is the only company to offer respiratory gating that follows a patient's natural breathing pattern. The RPM system works by placing a marker box on the patient's torso and monitoring respiration using cameras positioned in the treatment room. Extremely accurate gating is enabled by proprietary design features on the Clinac linear accelerator along with Varian's high-speed digital control system, which can provide beam-on times of less than 100 millisecond bursts.

Varian, based in Palo Alto, Calif., is a leading supplier of equipment and software for treating cancer. The company also is a supplier of components including X-ray tubes and flat-panel detectors for medical, scientific and industrial imaging.

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