Coded aperture imager with depth of interaction scintillators

In this study, a coded-aperture imager with a depth of interaction (DOI) detector was designed and its performance was evaluated using a Monte Carlo simulation. The DOI coded-aperture imager consisted of a modified uniformly redundant array (MURA) and four layers of a 16 × 16 matrix of 2 mm cubic scintillators. To improve its performance, the reconstructed images from each layer were combined using a hybrid maximum likelihood expectation maximization (h-MLEM) technique. The DOI coded-aperture imager demonstrated higher signal-to-noise ratios (SNRs) in the reconstructed images, when compared with conventional coded-aperture imagers with 2D pixelated scintillators. In addition, various types of scintillators were tested and compared with respect to their RV curves, detection efficiencies, and SNRs. Among the tested scintillators, gadolinium aluminum gallium garnet (GAGG) demonstrated the highest performance above 356 keV. However, for low-energy radiation (< 200 keV), the performance of all the scintillators were similar. Because the timing resolution is shorter than those of other scintillators, LaBr₃ could show a relatively high performance for measurement in high background conditions.