Robotics artificial vision and the CyberKnife capitalize on cutting-edge technology to deliver accurate doses of radiation. But radiation oncologists at the Memorial Sloan-Kettering Cancer Center, New York, developed a way to target pulmonary tumors by relying on much simpler technology: a patients ability to hold his or her breath.
The Deep Inspiration Breath Hold (DIBH) technique tries to take advantage of the fact that "if patients hold their breath during radiation, were not hitting a moving target anymore and were able to shrink the amount of normal lung that needs to be treated in order to make sure that were treating the tumor," said Ken Rosenzweig, M.D., assistant member in the Department of Radiation Oncology at Sloan-Kettering, and creator of the technique.
Another benefit of the technique: When people take in a deep breath, their lungs expand, but the tumor stays the same size. "So if you treat someone when theyre taking a deep breath in, the density of the normal lung surrounding the tumor decreases and a lot of the lung moves away from the radiation," Rosenzweig said. This allows a reduction in the toxicity of the radiation, since there is less normal lung treated.
To date, Rosenzweig and his colleagues have used the technique to treat more than 20 patients as part of a phase I dose escalation trial. Thus far, the treatment has been very well tolerated, said Rosenzweig. "Weve gone to shockingly high radiation doses81 gray, 84 graywith minimal to no toxicity....We felt that we needed these higher doses to get better tumor control, so we had to come up with new techniques if we wanted to get these higher doses in."
The technique requires the patient to hold his or her breath for 10 seconds at a time, and this is repeated five or six times during each treatment episode. The individual must take exactly the same level of breath for each treatment, which is measured with a device called a spirometer. The technique is used only when the patient can maintain the same breath level as the last treatment, which is perhaps the greatest limitation of the therapy.
"We only ask them to hold their breath for 10 seconds, but a sickly patient who has trouble walking from the living room to the bathroom would have a tough time holding their breath for even 3 seconds," acknowledged Rosenzweig.
The technique is now being administered only as part of the clinical trial at Sloan-Kettering. A number of other cancer centers, however, are using other techniques to monitor or control breath.
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