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| Home > Publications database > Particle imaging for daily in-roomimage guidance in particle therapy |
| Dissertation / PhD Thesis | DKFZ-2020-02658 |
2020
Abstract: Particle therapy exploits the highly localized depth dose profile of protons andlight ions to deliver a high dose to the target while largely sparing surroundinghealthy tissue. The steep dose gradient at the end of the ions range, knownas the Bragg peak, however, also makes particle therapy sensitive to rangeuncertainties. In current clinical practice, a major cause of range uncertaintiesresides in the conversion of the treatment planning x-ray CT to the patient specificrelative stopping power (RSP) map that is crucial for accurate treatmentplanning. By measuring the energy loss of particles after traversing the patient,particle imaging enables a more direct reconstruction of the RSP. In this thesis,different aspects towards the clinical implementation of particle imaging areinvestigated. First, a theoretical description of the point-spread function fordifferent particle radiography algorithms is developed in order to explain observedlimitations. A novel filtering technique to remove nuclear interactionevents in particle imaging is proposed and high quality experimental heliumion CTs are demonstrated. First results from an experimental comparison betweenparticle and x-ray CT modalities for RSP prediction in animal tissuesamples are presented. Furthermore, a novel technique for intra-treatment heliumion imaging based on a mixed helium/carbon beam is explored with thatrelative range changes in the millimeter regime were observable. Finally, novelparticle imaging detector designs are investigated. The thesis highlights thepotential of helium ion imaging for pre- and intra-treatment image guidancein particle therapy.
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