Supervisors info:
Ευστάθιος Στυλιάρης, Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Summary:
The current thesis focuses on Positron Emission Tomography (PET) simulations and especially on the imaging of the heart. Initially, it includes a theoretical introduction of some basic concepts that are considered useful for understanding the applications that follow. Some of these are the functionality of γ-Camera (Single Photon Emission Computerized Tomography, SPECT), the Positron Emission Tomography (PET), as well as the operation of the myocardium of the heart and the diseases that occur in it, since the imaging of the heart is studied through this thesis. Subsequently, several procedures are discussed that were implemented in SPECT-type simulations using the tool GEANT4/GATE. All the simulations were performed in this environment, so it was necessary for the understanding of the program to carry out some introductory applications, in which the absorption coefficients of different collimator materials and the spatial resolution (Point Spread Function) through the dimensionless sources were studied. In parallel, there was also considerable familiarity with the PAW (Physics Analysis Workstation) program, in which all the analysis of the data generated by GATE was performed.
The major part of this work is devoted to the simulations of a clinical PET scanner and then to the geometric reconstruction. More specifically, using the Lines Of Response (LORs), obtained by the Monte Carlo method, the intersection of these with a z-plan, i.e. the reconstructed source, is calculated. In order to improve the reconstruction algorithm, two kinds of event cut-off filters are applied: the energy filter, i.e., the rejection of Compton scattered events, and the time filter, i.e., the Time-of-Flight (ToF) filter. Finally, a phantom of a healthy heart was simulated, in the analysis of which transverse and longitudinal slices of it were generated. As already mentioned, a simulation of clinical interest was also performed by imaging a problem in the myocardium through the introduction of a 'cold' source into the previous phantom. In the end, important and interesting results are reported at the end of this paper.
Keywords:
Geometric Planar Image Reconstruction, Positron Emission, Point Spread Function, Time of Flight, Activity, Specific Activity, Line of Response, Phantom, Cold Source, Photon, γ-Camera
