[Effect of respiratory movement on cone beam computed tomography images].

To investigate the impact of respiratory movement to determine the target volume on cone beam CT (CBCT) for lung tumor, we used CIRS dynamic thorax phantom (Model-CIRS008) to simulate the sinusoidal motion of lung tumor. With a constant amplitude, the ratio of the time of near-end-expiratory and near-end-inspiratory (E/I) changed when it was scanned with CBCT. We analyzed the contrast changes of target by extracting the CT value of each pixel on the center line of the target movement direction.