Figure 2.

Target motion models. (a) Motion models acquired by tracking the position of target surrogates during clinical 4DCT procedures contain irregularities in both amplitude and period. (b) For comparison, an idealized $si{n}^4\left(\omega t\right)$ function is sometimes used as a model for respiratory motion. The dashed lines at 0.75 cm (orange), 0.5 cm (green), 0.3 cm (purple), and 0.2 cm (magenta) represent different amplitude gate thresholds used in delivery simulations with target motion.