Application of Multi-Pixel Photon Counter to positron emission tomography

The Multi-Pixel Photon Counter (MPPC) is a silicon based photon counting device consisting of multiple Avalanche Photodiodes operated in Geiger mode. In order to detect 511 keV photons we use MPPC devices with an active area of 3×3 mm² which are directly coupled to 3 × 3 × 15 mm3 scintillator crystals made of Lutetium Fine Silicate (LFS). Two gammadetectors of this kind are used to detect both coincident photons emerging from an e⁺e⁻ annihilation. The energy and the time resolution are measured. The very good performance of the gamma-detectors motivate the next step towards building a gamma camera consisting of a matrix of MPPC devices and scintillator crystals. First results concerning the design and the homogeneity of the read-out channels are presented. About 100 LFS crystals are tested. First studies on the properties of the ASIC which will be used for the multi-channel read-out are discussed. The experimental studies are supplemented with Monte Carlo simulations based on GEANT4. A full PET system is simulated in order to study and optimize the performance of the system in terms of spatial resolution.