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In this study, a coded aperture collimator and a 3D position-sensitive detector are combined to form the detection part of the coded aperture imaging system. Different types of detectors are irradiated with radioactive sources of different energies through the Monte Carlo method, and the depth information of detectors is studied on imaging performance. In the simulations, the coded collimator adopted the M-M coded method, and the detector types used included CZT, GAGG(Ce), NaI(Tl), CsI(Tl) and BGO. The detector arrays of different layers are reconstructed by direct convolution algorithm. The simulation results showed that when the gamma-ray energy was 60keV, the SNRs of the reconstructed images in the first layer array of various detectors were similar, reaching about 65, and the images in other layers could not be reconstructed accurately. For the gamma-rays with energy in the range of 122keV-511keV, the SNRs of reconstructed images in each layer of various detectors showed a step-like decline, and the SNRs of the reconstructed images in the first layer of the 3D position-sensitive detectors were greater than that of the conventional detectors. When the ray energy was 662keV or above, the SNRs of reconstructed images in each layer of various detectors were similar, especially for detectors with low density. Moreover, the SNRs of the images in first layer of all types of detectors were lower than that of the conventional 2D position-sensitive detectors, demonstrating that the depth information could not improve the detection performance for the energy above 662keV. Using the full-energy peak for image reconstruction had not improved the SNRs, because the majority of interactions were scatters events in this energy end. From the perspective of the whole energy range, the difference of the SNRs between each layer of BGO detector was the largest, when that of NaI(Tl) detector was the smallest, which was determined by the blocking ability of the detector. The angular resolutions of the reconstructed images in different layers of the 3D position-sensitive detectors for different energy rays varies slightly, whose values were about 2.9° (along the x-axis direction).
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