Fig. 4From: Combined effect of dose gradient and rotational error on prescribed dose coverage for single isocenter multiple brain metastases in frameless stereotactic radiotherapyRelative target coverage vs. rotational error for 3D rotation and axial rotation (inset). Target coverage was normalized to those of rotation-free cases. a 1-cm targets for different values of gradient steepness and iso-radius, b 1.5-cm targets, and c 2-cm targets. Smaller targets receive less coverage following rotation. Numbers next to data points are displacement values in mmBack to article page