## 3 Results
The 1 st row shows the sharp CT image (left) and the CT noisy projection for 100% of measurements (middle) as well as the \(18\times 18\) point spread function; the 2 nd row shows the blind restoration reconstruction results for 40%, 60%, 80% and 100% of measurements, respectively, from left to right (SNR = 40 dB); the 3 rd row shows the blind restoration reconstruction results for 40%, 60%, 80% and 100% of measurements, respectively, from left to right (SNR = 20 dB). **(a)** the sharp CT image; **(b)** the measured noisy projection (SNR = 40 dB); **(c)** the measured noisy projection (SNR=20 dB); **(d)** the point spread function; **(e)** the reconstruction result (SNR = 40 dB, Sampling ratio = 40%); **(e)** the reconstruction result (SNR = 40 dB, Sampling ratio = 60%); **(f)** the reconstruction result (SNR = 40 dB, Sampling ratio = 80%); **(g)** the reconstruction result (SNR = 40 dB, Sampling ratio = 80%); **(g)** the reconstruction result (SNR = 40 dB, Sampling ratio = 100%); **(h)** the reconstruction result (SNR = 20 dB, Sampling ratio = 40%); **(i)** the reconstruction result (SNR = 20 dB, Sampling ratio = 60%); **(j)** the reconstruction result (SNR = 20 dB, Sampling ratio = 80%); **(k)** the reconstruction result (SNR = 40 dB, Sampling ratio = 40%); **(l)** the reconstruction result (SNR = 20 dB, Sampling ratio = 100%). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**Sampling Ratio**} & **0.4** & **0.6** & **0.8** & **1** \\ \hline \multirow{3}{*}{Figure 1} & SART & — & 50.4383 \(\pm\) 0.1456 & 52.1108 \(\pm\) 0.1543 & 54.5095 \(\pm\) 0.1456 \\  & SART + TV & — & 51.3425 \(\pm\) 0.1278 & 54.8435 \(\pm\) 0.1435 & 56.8108 \(\pm\) 0.1376 \\  & Wavelet & — & 52.8898 \(\pm\) 0.1212 & 57.1615 \(\pm\) 0.1324 & 58.9218 \(\pm\) 0.1214 \\  & Proposed approach & 55.1612 \(\pm\) 0.1231 & 60.1005 \(\pm\) 0.1109 & 63.0505 \(\pm\) 0.1302 & 63.5126 \(\pm\) 0.1087 \\ \hline \multirow{3}{*}{Figure 2} & SART & — & 51.4795 \(\pm\) 0.2561 & 53.4909 \(\pm\) 0.2143 & 55.7349 \(\pm\) 0.2469 \\  & SART + TV & — & 53.9238 \(\pm\) 0.1812 & 55.8124 \(\pm\) 0.2452 & 56.7012 \(\pm\) 0.2376 \\  & Wavelet & — & 59.8122 \(\pm\) 0.1316 & 59.5905 \(\pm\) 0.1243 & 59.5137 \(\pm\) 0.1412 \\  & Proposed approach & 62.5796 \(\pm\) 0.1156 & 63.9292 \(\pm\) 0.1294 & 63.6970 \(\pm\) 0.1218 & 64.6231 \(\pm\) 0.1123 \\ \hline \multirow{3}{*}{Figure 3} & SART & — & 34.1959 \(\pm\) 0.1048 & 40.2794 \(\pm\) 0.1098 & 45.4973 \(\pm\) 0.1239 \\  & SART + TV & — & 36.4972 \(\pm\) 0.1345 & 43.4084 \(\pm\) 0.1324 & 47.8413 \(\pm\) 0.1267 \\  & Wavelet & — & 38.6082 \(\pm\) 0.1367 & 45.1803 \(\pm\) 0.1456 & 49.1661 \(\pm\) 0.1489 \\  & Proposed approach & 42.7369 \(\pm\) 0.0976 & 43.1990 \(\pm\) 0.0896 & 46.6093 \(\pm\) 0.0002 & 50.8476 \(\pm\) 0.0087 \\ \hline \multirow{3}{*}{Figure 4} & SART & — & 42.4213 \(\pm\) 0.2456 & 44.1773 \(\pm\) 0.2312 & 45.1659 \(\pm\) 0.3241 \\  & SART + TV & — & 43.8746 \(\pm\) 0.2891 & 45.4988 \(\pm\) 0.2561 & 46.6102 \(\pm\) 0.2134 \\  & Wavelet & — & 45.8239 \(\pm\) 0.2211 & 46.2769 \(\pm\) 0.2341 & 48.4986 \(\pm\) 0.2781 \\  & Proposed approach & 45.2660 \(\pm\) 0.1561 & 47.3095 \(\pm\) 0.1861 & 48.3834 \(\pm\) 0.1734 & 49.6093 \(\pm\) 0.1709 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Peak signal-to-noise ratio (PSNR) average performance comparison of the proposed algorithm with a series of algorithms, namely, SART [3], SART + TV [13], Patch + ordering Wavelet [14] (SNR = 40 dB).