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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 2016 - D. Verellen
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