230. A novel geometry for gamma-prompt imaging in proton therapy

Abstract

Purpose Proton therapy is a radiotherapy technique particularly engaging since it allows for a well-defined penetration and dose delivery. The estimation of the beam penetration is essentially based on the preliminary treatment planning. Real-time and in vivo estimation of the range of the proton beam will be very useful [1] : in this context, imaging from gamma-prompt plays a key role for therapy assessment [2] . Methods In this work we propose a novel geometry for gamma-prompt (see Figure). The setup is based on two detectors placed, along a rail, perpendicularly to the proton beam. Each detector is composed by a knife-edge collimator and a small Field-of-View (50 × 50 mm2) Gamma-camera based on a LYSO crystal and a position-sensitive photodetector. This detection geometry has been studied through Monte Carlo simulations developed with GATE and GEANT4. Results Many tests have been made in order to obtain the optimal detection configuration. With the best one, the following results have been achieved: proper counting-rate (about 50 kHz) and spatial resolution (about 4 mm). Conclusions The proposed geometry allows a good trade-off between counting rate and achievable spatial resolution in the region of interest undergoing to proton therapy. Further experimental measurements of clinical protocols are planned.