Abschlussarbeiten in der Medizinphysik




  • Correlation and Angular Distribution of Prompt Gammas (at proton energies of 70 - 200 MeV)
    The precision and optimization of ion/hadron therapy treatment needs a real-time monitoring of the longitudinal Bragg-peak position. Several non-invasive techniques have been proposed that exploit the detection of prompt gamma-rays issued from nuclear interactions of the irradiated region. A prove-of-principle experiment has been carried out in Krakow hadron-therapy centre to demonstrate the correlation between the gamma-rays emission and the Bragg-peak position. The experiment uses a 70 MeV proton beam through a carbon and PMMA tagret. For the gamma detection and spectroscopy a high purity germanium (HPGe) detector is used with an anti-compton-shield (ACS) detector. The ACS detector is a set of scintillator crystals (9 BGO and one NaI(Tl) ring) that surround the germanium crystal. The goal of the bachelor work is to construct the geometry of the setup and to simulate the experiment using the Geant4 toolkit. The simulation results are crucial for understanding of the experimental data and for setup optimization. The proposed bachelor work will be a well targeted point depending on the wish of the student with a well defined goal.


  • Construction of a new fibre tracker and development of a readout concept
    In the time-of-flight spectrometer a fibre tracker is used to measure dE/dx of the particles and to give a stop signal for the time-of-flight measurement. It consists of scintillating fibres which are glued to a fibre ribbon of 1mm thickness. As the existing fibre tracker with a width of 64mm doesn't cover enough of the solid angle to detect all particles a new and bigger one has to be build. The fibres are read out by SiPMs and at the moment every signal is discriminated and processed individually. For a bigger fibre tracker the number of readout channels wil increase dramatically, so a new method of processing the signals is needed. One possibility is to use a PETIROC chip. As the fibre tracker is also responsible for triggering, the whole readout is dependent on this and the development is an important contribution to the experiment. In this master thesis the new fibre tracker will be build in cooperation with our workshop and the readout electronics will be designed.
  • Geant4 Simulation of a time-of-flight spectrometer and optimization of a reconstruction algorithm
    Or group uses a time-of-flight spectrometer to measure nuclear cross sections and so validate the nuclear models used in Geant4. Therefore the whole measurement setup is implemented in a Geant4 simulation. The goal of this master thesis is to simulate data for comparison with the test beam data and to enhance the reconstruction algorithm to identify the particles measured in the spectrometer. Therefore the measured parameters in the different detectors have to be combined to allow a reconstruction of all individual particles. A challenge is the identification of all reactions products at the same time. The algorithm should work both for simulated and measured data.

Bewegte Tumore

  • Vergleich verschiedener Dosisberechnungsalgorithmen
    Folgendes Thema wird in enger Zusammenarbeit mit der Klinik für Strahlentherapie des Universitätsklinikums Aachen durchgeführt. Dort werden Patienten mit Gammastrahlung behandelt. Jede Bestrahlung wird im Vorfeld mit Hilfe der klinischen Planungsoftware Pinnacle berechnet. Alternativ lässt sich auch mit anderen Methoden und Algorithmen die Strahlendosis in einem Objekt bestimmen. Ziel der Arbeit ist es, verschiedene analytische und numerische Möglichkeiten der Dosisberechnung miteinander zu vergleichen. Für verschiedene Fälle soll ausgearbeitet werden, wo die Probleme der jeweiligen Berechnungsalgorithmen liegen und wie man gegebenfalls in der klinischen Planung diese berücksichtigen könnte. Zum Vergleich der berechneten Verteilungen sollen außerdem Messungen am medizinischen Linearbeschleuniger mit verschiedenen Phantomen gemacht werden.


Abschlussarbeiten können nach Rücksprache in allen drei Arbeitsgruppen (Flugzeitspektrometer, Braggpeak-Live-Monitoring, Klinikum) angefertigt werden. Es sind Arbeiten in den Bereichen Hardware, Simulation und Analyse möglich.

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Prof. Dr Achim Stahl, Dr. Karim Laihem (Braggpeak-Live-Monitoring, Patientensimulation), M.Sc. Ronja Lewke (Flugzeitspektrometer), Dipl. Phys. Nuria Escobar-Corral (Bewegte Tumore)