2017_SBRT_Course Book

Take home messages • Motion encompassing ITV is a reasonable 4D method, but overestimates the required margin. • 4D-CBCT / 4D-CT registration (e.g. mid-ventilation technique) allows for smaller margins. • Gated irradiation (free breathing / breath hold) requires patient compliance and increases treatment time. • Tracking technically challenging and requires building and verification of robust correlation/prediction models. • Tracking and gating only beneficial for relative large tumor motions (i.e. > 10-15 mm) • Tracking or Gating? Clinically probably equivalent, the difference is dose per beam spread out over region of motion versus somewhat larger dose concentrated at same location in lung (different penumbras?).

SBRT 2017 - D. Verellen