In-beam PET für 3He-Strahlen

At the clinical heavy ion treatment facility, which is under construction in Heidelberg, beams of He will be used for tumor irradiation. These will be monitored by means of in-beam PET for quality assurance. This requires a precise knowledge of the spatial distribution of beam induced positron emitters in the irradiated volume. For this an experiment at the Gesellschaft für Schwerionenforschung (GSI) with three mono-energetic {rm³He}-beams of 130.03 it A\rm M it e\rm V
to 207.92 it A\rm Mit e\rm V and mean intensities varying from 2.0 cdot 10⁸ to 3.5 cdot 10⁸ ions/s has been carried out. The beams were stopped in homogeneous thick targets consisting of lucite, graphite and gelatine, which were placed in the center of the field of view of the PET-scanner at the experimental carbon ion therapy at GSI [1]. Results on the production rate and the spatial distribution of {\rm³He} ion induced beta^a-activity will be presented. From these, the accuracy and resolution for determining the range of the {rm³He} primary beams is deduced. Furthermore, energy dependent cross sections for different reaction channels leading to positron emitters will be estimated from the experimental data.