In-beam PET monitoring technique for proton therapy: experimental data and Monte Carlo prediction

Abstract. Charged particle therapy is a precise radiotherapy method for the treatment of solid tumors. This method can deliver conformal dose distributions minimizing damage to healthy tissues thanks to its characteristic dose profile. However, the steep dose profile of charged particle beams (due to the Bragg peak) can result in over- or under-dosage in critical regions. Monitoring the range of the charged particles is therefore highly desirable. In this study, we use a planar in-beam PET system for the range verification of pencil beams in proton therapy. The planar geometry of the DoPET system is advantageous because it can be used online, i.e., during treatment. In the particle therapy community, the Monte Carlo (MC) codes are widely used to evaluate the radiation transport and interaction with matter. For this reason, the FLUKA MC code was used to simulate the experimental conditions of irradiations performed at the Cyclotron Centre Bronowice (CCB) proton therapy center in Krakow (PL). 130MeV pencil beams were delivered on phantoms mimicking human tissues. Different acquisitions are analyzed and compared with the MC predictions. The image reconstruction for experimental data and simulation is based on the Maximum Likelihood Estimation Method (MLEM) algorithm. A special focus in the paper will be on the validation of the PET detector response for activity range verification.