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Extent of geometric variations:
•
abdomen target –
mm to cm
(intra-fx amplitude)
•
pelvis target –
a few mm
(1 SD inter-fx)
Strategies for dealing with geometric variations in practice:
•
breathing control
•
real-time tumour tracking
•
reproducible filling of bladder and rectum
•
Adaptive treatment
+ internal margin (IM)
Summary of problem