Prediction of positron emitter distributions produced during 7Li irradiation

The clinical benefit of monitoring the applied dose in therapeutic carbon ion irradiation by means of in-beam PET has been proven at the experimental heavy ion treatment facility at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. For future treatment of tumour patients the application of different ion species with atomic numbers between 1 (protons) and 8 (oxygen) is conceivable [1]. It is highly desirable to extend the in-beam PET method also to these ions, in order to have the ability of verifying the treatment. Therefore, the correct modeling of positron emitter production is necessary, which requires the knowledge of cross sections of all possible nuclear reactions occurring in the tissue during irradiation. For the majority of therapeutically interesting ions these cross sections are not available in the required energy range. For the irradiation with Li ions a novel approach for predicting the positron emitter distribution has been developed. The feasibility of this approach is investigated by comparing experimental data with the prediction of positron emitter distribution in polymethyl methacrylate (PMMA) and inhomogeneous targets.