A PET Prototype for “In-Beam” Monitoring of Proton Therapy

The in-beam PET is a novel PET application to image the $\beta^{+}$ activity induced in biological tissues by hadronic therapeutic beams. Thanks to the correlation existing between beam-delivered dose profiles and beam-induced activity profiles, in vivo information about the effective ion paths can be extracted from the in-beam PET image. In-situ measurements, immediately after patient irradiation, are recommended in order to exploit the maximum statistics, by also detecting the contribution provided by the very short lived isotopes, e.g. $^{15}{\rm O}$. A compact, dedicated tomograph should then be developed for such an application, so as to be used in the treatment room.