Full-scale clinical implementation of a video based respiratory gating system

In an attempt to improve local control rates there has been a recent trend toward higher doses to smaller fields using three-dimensional conformal radiation therapy and/or intensity modulated radiation therapy. However, one limitation of these techniques is respiration-induced organ motion. Tumors in the lung can move from 1 to 3 centimeters during respiration. Because the composite field size does not change during treatment, the overall field size is typically enlarged to encompass the tumor through the entire respiration cycle. A respiratory-gated radiation treatment program was established at the Thompson Cancer Survival Center for the treatment of nonsmall cell lung cancer. A commercially available gating system was used to allow the selective delivery of absorbed dose to moving target volumes during time intervals when the target volume was within the intended region. This presentation describes the establishment process of respiratory gating and our experience in treating ten patients to date. The clinical efficiency and practicality of this modality are addressed. In addition, the patient specific QA procedures that are used to ensure that the correct dose is delivered safely are discussed