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CTV
PTV (Planning Target Volume)
OAR
PRV (Planning Organs at Risk Volume)
5 mm
The recommended CTV margin to create PTV is at least 5 mm.
B t PTV t id ki
’t b d f
d i
t i
l l ti
( i
u ,
ou s e s n can e use or os me r c ca cu a ons a r,
outside the body ...). Typical solutions:
1. To crop PTV by 3 mm (without reaching the skin) but treatment
planning carried out with 2-3 cm
2. To create PTV outside the body (margin for breathing) without croping
An additional “cropped” PTV volume will then be needed for
normalization purposes and DVH analysis