TVD 2017

CTV to PTV (Planning Target Volume) OAR to PRV (Planning Organs at Risk Volume)

The recommended CTV margin to create PTV is at least 5 mm.

But, PTV outside skin can’t be used for dosimetric calculations (air, outside the body ...).

Typical solutions in free breath treatments:

• To crop PTV by 3 mm (without reaching the skin) but treatment planning carried out with 2- 3 cm • 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