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

In the conventional centroid position estimation method, the effective field of view (FOV) cannot be extended beyond the centers of the two outside photomultiplier tubes. To extend the FOV, the authors have implemented statistical position estimation on a bar-detector with blackened end surfaces. Two statistical methods, maximum likelihood and minimum square error, were implemented to calculate the corresponding look-up tables (LUTs) from experimentally measured histogram data. The FWHM for both statistical methods is between 4 and 5.5 mm in the central 14 cm of the 16-cm bar length. In contrast, the centroid method provides a 10-cm FOV on a conventional bar-detector. A 2-D LUT method to save memory requirement was also implemented. Using the statistical methods it was possible to extend the FOV beyond the conventional limit to utilize 90% of the bar-detector area