Nuclear medical imaging using β+ γ coincidences from 44Sc radio-nuclide with liquid xenon as detection medium

We report on a new nuclear medical imaging technique based on the measurement of the emitter location in the three dimensions with a few mm spatial resolution using beta(+) gamma emitters. Such measurement could be realized thanks to a new kind of radio-nuclides which emit a gamma-ray quasi-simultaneously with the beta(+) decay. The most interesting radio-nuclide candidate, namely Sc-44, will be potentially produced at the Nantes cyclotron ARRONAX. The principle is to reconstruct the intersection of the classical line of response (obtained with a standard PET camera) with the direction cone defined by the third gamma-ray. The emission angle measurement of this additional gamma-ray involves the use of a Compton telescope for which a new generation of camera based on a liquid xenon (LXe) time projection chamber is considered. GEANT3 simulations of a large acceptance LXe Compton telescope combined with a commercial micro-PET (LSO crystals) have been performed and the obtained results will be presented. They demonstrate that a good image can be obtained from the accumulation of each three-dimensional measured position. A spatial resolution of 2.3 mm has been reached with an injected activity of 0.5 MBq for a Sc-44 point source emitter. (c) 2006 Elsevier B.V. All rights reserved.