Simulation of liquid xenon time projection chambers and 3γ camera with GATE

3γ imaging is a new nuclear medical imaging technique which has been suggested by Subatech laboratory, this technique involves locating three-dimensional position of the decay of an innovative radioisotope (β+, γ) emitter, the ⁴⁴SC. In order to demonstrate experimentally the feasibility of 3γ imaging, a first prototype, XEMISI (XEnon Medical Imaging System) was developed. The last published results of XEMISI, including the energy resolution obtained in the LXe and the very low electronic noise are very promising. The next step is to construct new prototype XEMIS2, which is a full liquid xenon cylindrical camera, dedicated to small animal imaging. To assess the performances of this camera for 3-gamma imaging, we developed a simulation of such a system using GATE (Geant4 Application for Emission Tomography). The simulation of XEMISI shows good data-simulation agreement. Based on this study, we are confident in the simulation of XEMIS2 and we expect a spatial resolution of ~500 J.lm and an energy resolution better than 5% depending on the electric field. Moreover, the full efficiency of the 3-gamma imaging technique has been estimated to ~5 % by simulating a rat phantom.