At the MedAustron facility in Wiener Neustadt ion-beam therapy tumours will be treated using protons and Carbon ions. In contrast to photon irradiation, ion beams show different characteristics: there is a sharp peak of deposited energy, the Bragg peak, at an accurately controllable depth. The incoming projectile ions undergo a series of nuclear interactions with the target nuclei. Lighter secondary particles are produced and propagate through the target tissue and generate a fragmentation tail directly after the Bragg peak, which is an important contribution to be considered for the treatment planning. In order to improve the understanding of the complex fragmentation processes and, thus, the contribution of the various fragments to the delivered dose during ion-beam therapy, differential and double differential cross sections need to be determined for all relevant occurring processes. These cross sections also play a key-role in any treatment planning system used to plan the optimal irradiation of cancer patients when using ion beams. In the context of this master thesis FLUKA simulations of a particle beam directed onto a thin target were performed. Reactions of 12C projectiles with energies ranging from 10 to 500 MeV/n impinging on various targets found in human tissue was studied. Most of the required particle types are already implemented in FLUKA, others are included by dedicated FORTRAN user routines. FLUKA is a well established simulation framework and allows for an estimation of differential and double differential cross sections where no experimental data are available. The result of this work is a cross section dataset, which could be used for an improvement of treatment planning systems used in ion-beam therapy, as well as for comparisons with other particle and ion transport codes.