Figure 4. A comparison of tumor displacements relative to end-expiration for another patient with and without abdominal compression, as a function of the normalized height of the respiratory curves relative to end-expiration.

The blue diamonds and red squares are with and without abdominal compression, respectively. The white arrows indicate the time course. If we allow the tumor displacement to be less than 5 mm relative to end-expiration for beam delivery, the abdominal compression increases the gating window from a range of (20%, 0%) to a range of (40%, 0%, 50%) in this particular case, resulting in a longer beam-on time per respiratory cycle.