Author Affiliations
1Beijing Engineering Research Center of Industrial Spectrum Imaging, School of Automation and Electrical Engineering, University of Science and Technology Beijing, Beijing 100083, China2State Nuclear Security Technology Center, Beijing 102445, Chinashow less
Fig. 1. Flow chart of physical detection process simulation of coded aperture γ imaging system
Fig. 2. Pattern of the coded mask: MURA(45×45)
Fig. 3. Illustration of the geometry setup of the imaging system
Fig. 4. Two-dimensional model of photon counting estimation for detection
Fig. 5. Reconstructed images of a point source at different distances and different FOV angles: the 1st, 2nd, 3rd, 4th, 5th and 6th columns are positions at (-29.64°, 23.65°), (0°, 23.65°), (0°, 0°), (28.66°, 0°), (29.64°, 0°) and (-14.87°, -14.87°); the 1st, 2nd and 3rd rows are the distance between the radiation source and the detector of 10 m, 15 m and 18 m, respectively
Fig. 6. Reconstruction images of 1.11×106 Bq 137Cs at distance of 4 m from detector with different FOV angles: the 1st, 2nd, 3rd, 4th and 5th columns are positions at (-29.64°, 23.65°), (0°, 23.65°), (0°, 0°), (28.66°, 0°) and (-14.87°, -14.87°), respectively
Fig. 7. (a) Reconstructed image of 3.7×107 Bq 137Cs point source at distance of 10 m from detector with FOV angle (0°, 0°), Gaussian fitting of normalized data points of pixel intensity distribution along the
X direction (b) and the
Y direction (c) of a single point source
Fig. 8. Reconstructed images of two 3.7×107 Bq 137Cs sources at the distance of 10 m from detector with acquisition time of 1 s
| 参数Parameter | 优化设计值Optimal design value |
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探测器Detector | 材料Material | NaI晶体 NaI crystal | | 单位像素大小Unit pixel size | 3.55 mm | | 厚度Thickness 阵列Array 整体面积Overall area | 9.5 mm 143×110 510 mm×390 mm | 编码板Coded mask | 材料Material | 钨合金Tungsten alloy | | 单位孔径Unit hole size | 20.1 mm×17 mm | | 厚度Thickness MURA阵列 MURA array 整体面积Overall area | 10 mm 45×45 1 020 mm×780 mm | 成像系统Imaging system | 焦距Focal length | 441 mm |
|
Table 1. Parameters of imaging system
放射源与成像系统的距离 Distance of sources and the system / m | 放射源的视场角度FOV angle position of radiation source |
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(-29.64°, 23.65°) | (0°, 23.65°) | (0°, 0°) | (28.66°, 0°) | (29.64°, 0°) | (-14.87°, -14.87°) |
---|
10 | 107.43 | 441.90 | 207.83 | 415.96 | 136.85 | 211.23 | 15 | 72.16 | 32.92 | 22.23 | 35.31 | 24.07 | 47.46 | 18 | 19.37 | 20.78 | 13.56 | 27.16 | 30.34 | 12.25 |
|
Table 2. CNR of reconstructed images from different positions of radioactive sources