Fluence-based Dosimetry using Fluorescent Nuclear Track Detectors

Carbon ion radiotherapy offers conformal dose coverage of deep-seated tumors and an enhanced radiobiological effectiveness compared to conventional photon treatment. Since the clinical outcome depends on both energy deposition and particle field composition, spectroscopic beam information is imperative for treatment planning and verification. Current fluence-based dosimeters have the potential to measure required quantities, but because of their size and electronic components, the majority of them is not suitable for in vivo applications. Fluorescent nuclear track detectors (FNTDs) are small and biocompatible aluminum oxide plates. Their superior spatial resolution allows for track-by-track characterization of heavy charged particle fields at clinically relevant fluences. Thus, their fluence-based dosimetry performance has been investigated within this thesis. Fluence assessment in multidirectional fields was realized by ion track reconstruction through the detector volume. The angular distribution could be measured accurately within 2° uncertainty. This translated into less than 5% overall fluence deviation from the chosen irradiation reference. Combination of this novel routine with an improved energy loss calibration curve based on 90 FNTD irradiations enabled fluence-based dose determination for mixed heavy ion fields. The analysis of a detector irradiated in Bragg peak proximity of a 270 MeV/u carbon ion field resulted in 85% dose agreement with treatment planning software prediction.

Level thesis:degree_level

master

Grantor dc:publisher

Universität Heidelberg

Year

2014

Author dc:creator

• Klimpki, Grischa

Contributors dc:contributor

• Bachert, Peter

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/17356

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:17356