Plastic scintillator investigations for relative dosimetry in proton-therapy

Plastic organic scintillators, polyvinyltoluene based, can be used with high sensitivity to detect 1-60 MeV proton beams. Thin scintillators can be applied to proton-therapy field as relative dosimeter thanks to their water-equivalent nature, high energy-light conversion efficiency, low dimensions and good proportionality to the absorbed dose at low stopping powers. Unfortunately, the quenching effect limits the use of the scintillators at high stopping powers. Moreover, they show a negligible radiation damage at the typical proton doses used in radiotherapy. Preliminary results have been obtained detecting in air both 60 MeV therapeutically proton beam at the Paul Scherrer Institute (PSI, Villigen-Zurich) and 24 MeV proton beam, at the Laboratorio Nazionale del Sud (LNS, Catania)