Enabling real-time reconstruction for high intrinsic resolution SPECT systems

Single Photon Emission Tomography (SPECT) is mainly limited by the trade-off between spatial resolution and sensitivity determined by the collimation. In this context, CdZnTe detectors enable higher intrinsic spatial resolution compared to previously used scintillators, even improved by using techniques for 3D positioning. Moreover, the compactness of these detectors enables new system architectures. To improve the sensitivity of SPECT systems without degrading their spatial resolution, a possible way is to adapt the field of view depending on the kind of acquisition and the morphology of the patient, using flexible detection heads. That means computing reconstruction fast enough to determine interesting area where to focus detectors. This task is problematic because of the complexity of data to be processed, as the high resolution of detectors makes measurements sparse, and because of the dependency of reconstruction to head position, that must be taken into account. The aim of the present study is to propose new approaches to deal with this massive amount of complex information in real time to dynamically adapt the field of view. Implementation techniques from MLEM algorithm are proposed in order to fasten the reconstruction and adapt the geometrical configuration during the examination, and thus improve the sensitivity of the system without degrading its spatial resolution.