Vorschau

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Abstract

In heavy ion therapy, precise knowledge of fluence, energy and particle type is necessary for an adequate treatment planning. The current status of the verification of a patient's individual treatment plan relies mainly on dose measurements in a water phantom which means a limited validity with respect to the biological effect on tissue. A technology which can be used for accurate in-vivo verifications would improve the planning process considerably. Biocompatible fluorescent nuclear track detectors (FNTDs) were therefore investigated in this thesis as a precursor with respect to the detection of heavy charged particles (HCPs) with penetration depth. For that reason, irradiations of FNTDs with protons and carbon ions in different depths of PMMA were performed at the Heidelberg Ion-Beam Therapy Center (HIT). In these experiments, the detectors have shown their suitability to detect HCPs with depth. Proton densities for penetration depths lower 11.5 cm in PMMA were determined with an average deviation of 3.3% and a maximum deviation of 4.5% from FLUKA simulated data. In a carbon ion beam, densities of carbon ions deviated systematically by 6.8% on average from treatment planning system data for depths lower 12.4 cm, most likely due to the detection of fragments such as boron ions. In further investigations, methods for the determination of angular distributions of protons were examined showing that stacks of images give the most accurate information on deflection angles of particles. Furthermore, incipient steps regarding the discrimination of different particle types in a carbon ion beam were done showing that carbon ions and lighter fragments such as protons and helium ions can be discriminated very easily using FNTDs.