103 / 815
Volumes in ICRU50 - 1993
Planning Target Volume (PTV)
The PTV is a geometrical concept
Movements of tissues containing CTV
Movements of patient
Variations in size and shape
Variations in beam geometry characteristics
PTV = CTV + margin for geometrical variations
Aid for treatment planning; dose to PTV
representing dose to CTV
CTV with margin forming the PTV