VMAT CSI planning
VMAT CSI plans were generated on
Eclipse v15.6 (Varian Medical Systems, Palo Alto, CA) using 6 MV energy
beams, Photon Optimization (PO) algorithm, Analytical Anisotropic
Algorithm (AAA) dose calculation, and a calculation grid of 2.5 mm. Two
full arcs were used to treat the brain and a single arc was used to
treat the spine, with an overlap of at least 2 cm between the brain and
spine fields. Brain and Spine isocenters were placed such that there was
only longitudinal shift between them. Auto-feathering was enabled during
optimization to create smooth dose gradients in the overlapping areas
between fields. The spine arcs used avoidance sectors to limit dose
entering through the arms. VMAT CSI plans were normalized at 95% PTV
coverage by the prescription dose of 36 Gy.