Fig. 1. Network structure of DI-Net. (a) Overall schematic of DI-Net; (b) network structure of D-Net (M＝512，N＝768，k＝16) and I-Net (M＝256，N＝256，k＝32)

Fig. 2. Schematic of the experimental setup

Fig. 3. Reconstruction results of vascular phantom based on 128 projection views (All color bars stand for amplitudes of pixels on images). (a) Reference image; (b)(d) images reconstructed by FBP algorithm, Post-Unet algorithm, and DI-Net algorithm, respectively; (e)(g) difference images between the reference image and the images reconstructed by FBP, Post-Unet, and DI-Net, respectively; (d) quantitative evaluation results of the reconstruction images

Fig. 4. Reconstruction results of vascular phantom based on 256 projection views (All color bars stand for amplitudes of pixels on images). (a) Reference image; (b)(d) images reconstructed by FBP algorithm, Post-Unet algorithm, and DI-Net algorithm, respectively; (e)(g) difference images between the reference image and the images reconstructed by FBP, Post-Unet, and DI-Net, respectively; (d) quantitative evaluation results of the reconstruction images

Fig. 5. Quantitative evaluation results of different algorithms on the vascular test dataset (To facilitate observation, the ordinate of the boxplot in the small dashed box is stretched and separately shown in the large dashed box). (a)(d) MSE; (b)(e) PSNR; (c)(f) SSIM

Fig. 6. Reconstruction results of mouse slice based on 128 projection views (All color bars stand for amplitudes of pixels on images). (a) Reference image; (b)(d) images reconstructed by FBP algorithm, Post-Unet algorithm, and DI-Net algorithm, respectively; (e)(g) difference images between the reference image and the images reconstructed by FBP, Post-Unet, and DI-Net, respectively; (d) quantitative evaluation results of the reconstruction images

Fig. 7. Reconstruction results of mouse slice based on 256 projection views (All color bars stand for amplitudes of pixels on images). (a) Reference image; (b)(d) images reconstructed by FBP algorithm, Post-Unet algorithm, and DI-Net algorithm, respectively; (e)(g) difference images between the reference image and the images reconstructed by FBP, Post-Unet, and DI-Net, respectively; (d) quantitative evaluation results of the reconstruction images

Fig. 8. Quantitative evaluation results of different algorithms on the mouse slice test dataset. (a)(d) MSE; (b)(e) PSNR; (c)(f) SSIM

Table 1. Mean value of quantitative evaluation results for different algorithms on the vascular test dataset

Table 2. Mean value of quantitative evaluation results for different algorithms on the mouse slice test dataset

Table 3. Comparisons of consuming time for different algorithms　unit：s