2017_IGRT course book

Can there be a good surrogate for the position of a lung/liver tumour?

• No surrogate is so good that you can avoid IGRT

• 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