TVD 2017

Target volumes – PTV

• 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) = Internal Target Volume (ITV) • ITV + “Set-up Margin” (SM) = PTV • Inadequate PTV margins: • risk increased treatment failure • Excessive PTV margins risk: • increased treatment toxicity