Scintillator characterization at energies relevant for a prompt gamma detection system in particle therapy

The proton therapy in oncology requires instantaneous and reliable particle range verification, which can be achieved using prompt gamma emissions. The characteristic requirements of prompt gamma detection include the energy range of up to several MeV, increased background due to secondary emissions and high counting rates. Different concepts make use of the prompt gamma emissions for verification of dose deposition location, e.g. collimated systems or Compton cameras. Additionally to prompt gamma imaging, the prompt gamma timing method has been proposed, utilizing the proton transit time inside the body. Those approaches imply different needs on energy-, spatial- or timing-resolution of the detection system. Various scintillator materials with multiple shapes have been characterized with respect to those requirements using classical photomultiplier tubes (PMT) and different experimental setups and locations. The light output, non-linearity and energy resolution were measured using gamma sources. The timing was characterized at the ELBE facility at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), using the bremsstrahlung beam with photons up to 12.5 MeV. Measurements at the 3 MV Tandetron accelerator at HZDR provided information of the energy resolution at therapy relevant energies of 4.4 MeV.