The Ph.D. dissertation focuses on the simulation and reconstruction of readout data obtained from a photodetectors matrix coupled with a scintillator crystal. In particular, it presents the outcomes of the in-depth examination of three major reconstruction techniques to optimize the following enquiries: how to match the simulated and experimental data as much as possible; how to enlarge the field of view and improve both the spatial and the energy resolutions, compared to the simple Centroid method; how to evaluate the depth of interaction of the gamma ray inside the crystal. The main reconstruction program implemented and adopted is based on the Maximum Likelihood algorithm, even though some preliminary tests were also carried out using a Feedforward Neural Network. To better prove the adaptability and flexibility of the algorithms implemented and the reliability of our Gamma Camera simulator, it was decided to train both reconstruction programs only with simulated data, while their performances were validated with also experimental data, obtained from setups with different crystal/photodetectors configurations and energies.
La dissertazione è focalizzata sulla simulazione e ricostruzione dei dati ottenuti da una matrice di fotorivelatori accoppiata con un cristallo scintillatore. In particolare, sono descritti i risultati ottenuti tramite l’impiego di tre tecniche di ricostruzione (baricentro, massima verosimiglianza e reti neurali) al fine di: far corrispondere i dati simulati e sperimentali il più possibile, allargare il campo visivo, migliorare la risoluzione sia spaziale che energetica e valutare la profondità di interazione dei raggi gamma all'interno del cristallo. Il programma di ricostruzione principale adottato e implementato si basa sull'algoritmo di massima verosimiglianza, anche se nel corso del dottorato alcune prove preliminari sono state effettuate anche mediante l’utilizzo di una rete neurale di tipo feedforward. Per meglio dimostrare l'adattabilità e la flessibilità degli algoritmi implementati e l'affidabilità del nostro simulatore di Gamma Camere, si è deciso di addestrare entrambi i programmi di ricostruzione solo con dati simulati, mentre le loro prestazioni sono state validate anche con dati sperimentali, ottenuti con diverse configurazioni cristallo/rivelatori ed energie.
Study and application of reconstruction methods to determine the interaction position in gamma ray scintillation detectors
MARONE, ALESSANDRO
Abstract
The Ph.D. dissertation focuses on the simulation and reconstruction of readout data obtained from a photodetectors matrix coupled with a scintillator crystal. In particular, it presents the outcomes of the in-depth examination of three major reconstruction techniques to optimize the following enquiries: how to match the simulated and experimental data as much as possible; how to enlarge the field of view and improve both the spatial and the energy resolutions, compared to the simple Centroid method; how to evaluate the depth of interaction of the gamma ray inside the crystal. The main reconstruction program implemented and adopted is based on the Maximum Likelihood algorithm, even though some preliminary tests were also carried out using a Feedforward Neural Network. To better prove the adaptability and flexibility of the algorithms implemented and the reliability of our Gamma Camera simulator, it was decided to train both reconstruction programs only with simulated data, while their performances were validated with also experimental data, obtained from setups with different crystal/photodetectors configurations and energies.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/74482