Bar-detector with extended field of view for a modular SPECT system

In the conventional centroid positon estimation method, the effective field of view (FOV) of a scintillation bar-detector cannot be extended beyond the centers of the two outside photomultiplier tubes (PMTs). To extend the FOV, statistical position estimation on a bar-detector with blackened end surfaces is implemented. Maximum likelihood (ML) and minimum square error (MSE) position estimation lookup tables (LUTs) are calculated from experimentally measured histogram data. Both statistical estimators provide a 14-cm FOV on a 16-cm bar, with 4-mm to 6-mm full width half maximum (FWHM) within the FOV. In contrast, the centroid method provides a 10-cm FOV on a conventional bar-detector. In order to reduce the size of LUTs and memory requirements, the feasibility of using local, 2-D LUTs for position estimation is demonstrated. Using statistical position estimation methods and scatter-free sources, it is possible to extend the FOV beyond the conventional limit to utilize 90% of the bar-detector area