IMRT 2018

PTV: disadvantages

The PTV concept works only when a)The dose is homogeneous

b)The dose is invariant after translations/rotations c)Margins are defined correctly w.r.t. the geometrical uncertainties

The tradeoff between target coverage and OAR sparing is unbalanced

N.B. IGRT aims at reducing PTV margins but does not address the shortcomings of PTV-based RT