Figure 9

4D treatment planning for a lung tumor. Dose distributions (color-wash) on the reference 4DCT phase (grey-levels, CTV contour in white) for different motion mitigation techniques in comparison to (a) the dose distribution for a stationary target. (b) Internal margins can not properly mitigate target motion. Interplay between beam scanning and organ motion leads to a deteriorated dose distribution. Tracking (c) and gating (d) allow appropriate mitigation of target motion. Resulting dose distributions cover the CTV comparable to (a). Motion parameters: respiratory period 2 s, initial respiratory phase 90°, Lujan model (n = 2), synchrotron extraction modeled for HIT.