Simulation of a high performance γ-camera concept for PET based on liquid xenon and gaseous photomultiplier

We present the results of GEANT3 simulations of a full PET system made of liquid xenon (LXe)-TPC γ-camera modules. In such camera both ionization and scintillation signals will be detected to provide the three coordinates and the energy of the converted γ-ray. For that purpose, we will develop advanced ionization detectors operating in liquid xenon as well as fast cryogenic gaseous photomultipliers (GPMs) with CsI photocathodes, dedicated to the detection of the LXe scintillation signal. The measurement of the conversion coordinates and the energy will allow to reconstruct the correct Compton sequences and thus to identify the first interaction vertices of both correlated annihilation γ-rays. Moreover, measurement of the depth of interaction (DOI) will lead to a parallax-free tomograph. The GEANT3 simulation code of the LXe-TPC PET provided very promising expected performances from a realistic detector: good sensitivity to 511 keV γ-rays (-93% for a 9 cm depth LXe module) and good 3D spatial resolution (250 μm FWHM for first interaction vertex localization); the latter is close to the intrinsic physical limitations of the method.