  A new technique for medical imaging, "3{\gamma} imaging", is studied by our
group at SUBATECH for few years. A small liquid xenon time projection chamber
prototype has been built in order to demonstrate the feasibility of this
technique. With an ultra-low-noise front-end electronics, the energy deposit
and resolution of 511 keV {\gamma}-ray as a function of drift electric field
(E) is measured with high precision. 500 {\mu}m of z resolution is estimated by
measuring the charge carriers drift velocity and time resolution.
