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Système modulaire de traitement pour la tomographie d'émission à partir de détecteurs CdZnTe

Abstract : In the last decades, new CdTe/CdZnTe based detectors enable enhanced performances on medical imaging systems, especially in SPECT imaging. This improvements are achieved by developing simultaneously the precise localization of interaction in detectors, the collimator, matching between the system geometry and the specificities of the examination, reconstruction algorithms, and data processing architectures. In addition to their interesting intrinsic performances, CdZnTe detectors benefits from their compactness compared to previously used scintillators and photo-multiplicators. This compactness enables more flexible systems. New designs are thus proposed, especially in cardiac imaging.Performances of SPECT systems are limited by a trade-off between the spatial resolution, the sensitivity and the field of view imposed by the collimator and the available detection surface. In order to go further this compromise, this work focuses on possibilities for online adaptation offered by flexibles designs. Adaptation on a system composed of several independent detection heads already proposed by industrials is under study. We propose to adapt the angular sampling of heads, enabling acquisition protocols more accurate for different patient morphologies and examination protocols.The purpose of this work is to propose acquisition and adaptation protocols enabling the reconfiguration of the angular sampling of detection heads depending on an estimation of the imaged object. Algorithmic solutions are proposed in order to compute the reconstruction in real time from more complex data because of additional degrees of freedom and detector precision. The resulting estimation have to enable the identification of informative areas in order to focus detection heads on it. Simulations approves theoretically the use of our rapid algorithmic solution on a modular system carrying a reliable estimation of the object. Some experimental results validate the system model and the reconstruction algorithm. Then, some adaptation strategies are investigated using simulations.
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Mélanie Bernard. Système modulaire de traitement pour la tomographie d'émission à partir de détecteurs CdZnTe. Traitement du signal et de l'image [eess.SP]. Université Grenoble Alpes, 2017. Français. ⟨NNT : 2017GREAM063⟩. ⟨tel-01866747⟩

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