What is respiratory gating?
Respiratory gating is a technology that matches radiation treatment to a patient's respiratory pattern. When one breathes, the chest wall moves in and out, and any structures inside the chest as well as inside the upper abdomen move with that respiration also. In the past, when we've aimed radiation beams at a target inside those areas of the body, we had to account for that movement and treat a larger area because the target may move in and out of the treatment field. With respiratory gating, we can now sequence the x-ray beam to be on during certain phases of respiration so that we know where the cancer target is during those phases. This improves our accuracy.

What specific kinds of cancers does this equipment treat?
It's most helpful for targets that are moving during radiation, such as tumors in the upper abdomen like lesions or cancers in the liver, and lung cancers in the outer regions of the lung. In some women with breast cancer, it is difficult to angle the beams off the heart and during inspiration the heart may be displaced.

How does the new respiratory gating equipment allow for improved cancer treatment?
It improves treatment in two ways: first, by allowing us to treat just the tumor and much less surrounding normal tissue. Second, we're able to treat lesions in the liver that we were unable to radiate previously. The liver is very sensitive to radiation, and when we were unable to match the x-ray beams to the movement, we would be at risk of too much liver damage.

How long has this new treatment been available at ABCCC?
We treated our first patient here on April 4, 2003. The technology has been around for about two years and longer than that in research. We had a physicist here from another SHC Center helping us to treat our first patient. Different centers are investigating different ways of using the system, so the technology is still evolving.

What is most important for patients to know about respiratory gating?
That it's available, but not beneficial in every patient. Patients need to be aware that using this system requires specific breathing instructions and that some patients will not be physically able to comply with those instructions. If a patient had emphysema, for example, it might be difficult to breathe in the timed fashion necessary for this treatment. It has to be appropriate from a medical standpoint and achievable from a patient's standpoint.

Are there risks or side effects associated with this kind of treatment?
No. It just takes a bit more time on the patient's part to do the planning portions of the treatment.

Can respiratory gating be combined with other forms of treatment to target specific cancers?
Usually respiratory gating is combined with conformal radiation therapy. If a Center has the respiratory gating technology, it would also be equipped to use either three-dimensional treatment planning, or intensity modulated radiation therapy (IMRT), which are both ways of highly localizing the cancer and adjusting the radiation dose distribution for better accuracy.

Using this new technology is very logical and it allows us to greatly improve accuracy and to avoid damage to surrounding healthy tissue.