Physics Bucharest 2017

RBE for protons

• Clinically, a value of 1.1 is adopted • Increased RBE potentially relevant at distal edge • RBE may lead to effective over-range of 1-2mm (Paganetti 2002, mono-energ tic Protons, in-vitro) Some protons are more equal than others

(Paganetti 2002)

(in-vivo studies, Center of SOBP)

(in-vitro studies, Center of SOBP)

Residual range: ~25 m m → Bragg peak position