Figure 1From: 4D treatment planning for scanned ion beamsSchematic drawing of 3D tumor motion in the coordinate system of the scanned ion beam. The tumor is depicted in its reference position (grey) and in a second position corresponding to a different motion phase (red). The scanning coordinate system consists of iso-energy layers (z in water-equivalent units) as well as grid positions within these layers (x, y). Motion of a grid position is indicated by a motion vector (white). Δ(x, y, z) are the parameters required for motion compensation.Back to article page