ESTRO Brachytherapy for Prostate Cancer 2018

Planning Target Volume

PTV

The PTV surrounds the CTV with a margin to compensate for the different types of variations and uncertainties of treatment delivery to the CTV.

The PTV is a geometrical concept, introduced for treatment planning.

A margin must be added to the CTV

• to compensate for expected physiological movements and variations in size, shape and position of the CTV during therapy (internal margin) • for uncertainties (inaccuracies and lack of reproducibility) in patient irradiation.