Simulation and evaluation of a new PET system based on liquid xenon as detection medium

Due to its intrinsic physical properties, high density and atomic number, fast scintillation, high scintillation light yield and low ionization potential, liquid xenon is an excellent medium for the tracking and the accurate energy measurement of γ-rays in the MeV energy domain. The use of liquid xenon associated to a micro gap structure device to measure 511 keV γ-rays in PET tomograph is under investigation at Subatech. A GEANT3 simulation of a full PET design made of LXe-TPC modules has been developed and the first estimations of the performances from a realistic detector are very promising: good overall sensitivity to 511 keV γ-rays (~ 93% for a 9 cm depth LXe module), good three-dimensional spatial resolution (250 μm FWHM on the localization of the first interaction vertex). The measurement of the 3 coordinates of the interaction vertices and the energy loss associated allow to reconstruct the Compton sequence of correlated annihilation photons. Hence the capability to identify the first interaction vertex leads to major progresses in PET imaging: a parallax free PET tomograph with a high detection sensitivity of 190 kcps/kBq/ml and a 3-dimentionnal spatial resolution of 1.7 mm close to the physical intrinsic limits. The performances of the proposed LXe PET design are compared to a standard BGO PET camera operating in 3D acquisition mode.