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Can there be a good surrogate for the
position of a lung/liver tumour?
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No surrogate is so good that you can avoid IGRT
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Solution 1: use large margins ( approx equal to free breathing)
➢
Starkschall et al IJROBP 2011:
treatment using
methods designed to mitigate the effects of
respiratory motion (breath hold or gating) with
setup based on landmarks other than the actual
tumour position requires margin of 0.7 to 0.8 cm