Figure 3

Respiratory waveforms during image acquisition for both 4DCT scans at the level of tumor in patient 13. Images were reconstructed from acquisitions at two consecutive couch positions (table increments of 2 cm) as evidenced by the discontinuous waveforms. The RPM amplitude at the end-expiration tumor position was similar in both 4DCT scans (A), but a larger difference in respiratory amplitude was seen at the end-inspiratory tumor position (B).