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Target volumes – PTV
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ICRU 62 suggested 2 components to the PTV:
Internal Margin IM – for eg organ movement
Setup Margin SM – for set-up inaccuracies
CTV + “Internal Margin” (IM) = ITV
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ITV + “Set-up Margin” (SM) = PTV
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These are useful to remind about the basis of errors
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ITV= Internal Target Volume