Table 6. The SNR and CNR of SNs under different tube current and reconstruction algorithm.
| mA | Reconstruction algorithm | CTnodule | SDnodule | CTair | SDair | SNR | CNR |
|---|---|---|---|---|---|---|---|
| 20 | DLIR-L | 132.47±24.61 | 37.62±5.61 | −1,000.85±2.87 | 34.68±3.91 | 3.57±0.80 | 33.01±4.48 |
| DLIR-M | 123.30±1.45 | 30.37±5.75 | −1,001.70±5.08 | 23.50±4.49 | 4.16±0.81 | 48.12±4.19 | |
| DLIR-H | 119.82±13.01 | 19.10±2.23 | −1,000.42±4.01 | 13.76±1.37 | 6.28±0.21 | 82.01±8.66 | |
| 30%ASIR-V | 145.01±51.71 | 101.05±27.33 | −964.33±6.02 | 76.91±8.35 | 1.64±1.11 | 14.58±2.31 | |
| 50%ASIR-V | 148.60±40.99 | 84.53±28.43 | −974.73±0.49 | 62.30±4.28 | 2.07±1.41 | 18.09±1.55 | |
| 80%ASIR-V | 142.39±36.89 | 64.65±5.78 | −982.78±4.14 | 50.08±7.39 | 2.23±0.69 | 22.91±4.53 | |
| FBP | 153.82±19.94 | 123.09±41.4 | −957.41±2.45 | 86.56±4.77 | 1.43±0.78 | 12.87±0.90 | |
| 30 | DLIR-L | 136.05±15.51 | 33.83±11.34 | −1,000.69±6.06 | 28.89±3.99 | 4.49±2.13 | 39.85±5.50 |
| DLIR-M | 133.47±17.93 | 25.67±4.20 | −1,002.88±4.74 | 20.05±1.45 | 5.38±1.67 | 56.89±4.62 | |
| DLIR-H | 125.32±4.87 | 18.76±7.1 | −1,001.66±3.49 | 11.53±1.47 | 7.42±2.71 | 98.76±12.28 | |
| 30%ASIR-V | 144.64±17.08 | 108.56±25.09 | −972.80±4.54 | 66.56±3.77 | 1.39±0.37 | 16.84±1.25 | |
| 50%ASIR-V | 153.80±20.49 | 95.07±477.73 | −910.55±4.62 | 58.91±4.88 | 1.92±0.90 | 15.13±8.80 | |
| 80%ASIR-V | 158.00±11.77 | 64.20±5.90 | −987.23±1.61 | 44.58±4.34 | 2.46±0.04 | 25.87±2.80 | |
| FBP | 158.72±33.67 | 136.47±14.86 | −958.44±5.87 | 82.93±4.39 | 1.19±0.36 | 13.51±1.14 | |
| 50 | DLIR-L | 131.74±15.93 | 29.32±2.39 | −1,005.60±1.03 | 25.70±1.84 | 4.53±0.82 | 44.37±2.46 |
| DLIR-M | 133.83±17.33 | 20.07±1.31 | −1,005.77±1.05 | 18.15±1.44 | 6.73±1.35 | 63.01±4.21 | |
| DLIR-H | 133.20±18.21 | 13.14±1.21 | −1,005.36±1.04 | 10.57±3.78 | 10.20±1.76 | 108.24±8.59 | |
| 30%ASIR-V | 128.45±27.67 | 99.82±2.88 | −975.60±0.47 | 62.88±4.39 | 1.28±0.24 | 17.60±1.22 | |
| 50%ASIR-V | 150.80±16.33 | 78.29±12.66 | −928.88±0.38 | 54.61±3.69 | 1.94±0.09 | 19.244.36 | |
| 80%ASIR-V | 148.07±16.06 | 55.56±14.14 | −989.44±1.68 | 43.93±3.89 | 2.80±0.89 | 26.02±2.14 | |
| FBP | 140.15±8.38 | 127.27±14.80 | −962.77±4.15 | 79.62±3.77 | 1.11±0.17 | 13.88±0.76 | |
| 70 | DLIR-L | 134.19±5.38 | 26.66±0.43 | −1,005.07±2.78 | 21.91±1.95 | 5.04±0.28 | 52.26±4.64 |
| DLIR-M | 130.75±7.75 | 21.62±2.72 | −1,004.95±1.89 | 15.08±1.39 | 6.12±0.93 | 75.75±6.82 | |
| DLIR-H | 131.96±6.97 | 11.57±1.58 | −1,004.71±2.23 | 8.98±0.52 | 11.58±2.06 | 126.84±7.31 | |
| 30%ASIR-V | 136.75±16.69 | 100.77±5.39 | −974.18±6.81 | 66.08±11.35 | 1.35±0.09 | 17.11±2.59 | |
| 50%ASIR-V | 143.89±3.42 | 96.44±6.86 | −982.99±3.47 | 51.68±6.57 | 1.50±0.07 | 22.03±2.65 | |
| 80%ASIR-V | 144.64±20.62 | 54.30±7.09 | −992.57±2.55 | 37.76±6.85 | 2.67±0.27 | 30.73±5.15 | |
| FBP | 130.86±27.04 | 142.51±12.10 | −970.38±2.21 | 70.65±3.82 | 0.91±0.13 | 15.61±0.60 | |
| 90 | DLIR-L | 127.10±8.85 | 20.00±4.38 | −1,005.48±3.08 | 19.03±1.99 | 6.55±1.36 | 60.01±6.91 |
| DLIR-M | 129.49±10.05 | 17.47±0.23 | −1,004.78±2.90 | 14.01±2.13 | 7.42±0.65 | 82.32±13.43 | |
| DLIR-H | 128.14±9.59 | 10.89±3.69 | −1,004.33±2.78 | 7.99±0.50 | 12.73±4.27 | 142.18±9.96 | |
| 30%ASIR-V | 140.05±5.83 | 98.06±17.89 | −977.86±4.46 | 58.36±6.77 | 1.45±0.20 | 19.34±2.31 | |
| 50%ASIR-V | 139.94±18.58 | 75.11±17.85 | −981.30±5.79 | 53.50±6.57 | 1.90±0.28 | 21.18±2.79 | |
| 80%ASIR-V | 140.33±20.82 | 48.32±4.45 | −993.23±0.29 | 36.89±3.60 | 2.91±0.37 | 30.93±3.15 | |
| FBP | 148.58±15.07 | 128.82±16.39 | −973.46±3.32 | 65.49±3.69 | 1.16±0.05 | 17.16±0.79 | |
| 100 | DLIR-L | 130.30±10.41 | 31.39±7.70 | −1,003.58±1.73 | 20.10±1.86 | 4.39±1.52 | 56.77±5.72 |
| DLIR-M | 130.29±10.56 | 22.84±4.97 | −936.01±8.93 | 13.83±1.12 | 6.00±2.00 | 76.29±11.36 | |
| DLIR-H | 129.35±11.64 | 11.22±2.04 | −1,004.52±1.63 | 8.25±0.83 | 11.95±3.54 | 138.48±14.36 | |
| 30%ASIR-V | 131.14±10.05 | 110.53±33.36 | −980.39±2.91 | 56.74±2.65 | 1.27±0.42 | 19.62±1.01 | |
| 50%ASIR-V | 139.49±10.66 | 106.23±24.79 | −985.36±0.81 | 49.65±0.74 | 1.39±0.47 | 22.66±0.55 | |
| 80%ASIR-V | 149.41±12.31 | 69.22±21.32 | −991.70±3.29 | 36.84±2.52 | 2.29±0.68 | 31.06±1.99 | |
| FBP | 147.03±5.95 | 160.67±47.45 | −972.42±3.41 | 67.85±4.38 | 0.96±0.25 | 16.55±1.21 | |
| 120 | DLIR-L | 133.49±5.21 | 22.91±0.88 | −1,004.85±4.49 | 16.23±1.81 | 5.84±0.41 | 70.76±8.14 |
| DLIR-M | 132.21±6.44 | 16.87±2.19 | −1,002.74±4.76 | 12.48±0.89 | 7.91±0.96 | 91.26±6.75 | |
| DLIR-H | 133.11±5.52 | 11.57±2.85 | −1,003.72±4.49 | 6.54±0.40 | 12.15±3.92 | 174.28±10.47 | |
| 30%ASIR-V | 135.42±11.56 | 77.03±13.92 | −981.61±0.96 | 51.03±1.63 | 1.78±0.17 | 21.90±0.71 | |
| 50%ASIR-V | 133.35±9.09 | 60.87±20.50 | −986.43±1.64 | 44.55±2.51 | 2.36±0.77 | 25.20±1.61 | |
| 80%ASIR-V | 139.51±10.50 | 35.79±13.23 | −994.70±3.39 | 33.43±2.64 | 4.25±1.46 | 34.08±2.93 | |
| FBP | 148.56±22.65 | 130.11±22.93 | −966.88±2.71 | 72.17±1.84 | 1.15±0.18 | 15.46±0.50 | |
| 150 | DLIR-L | 131.75±3.45 | 18.11±1.65 | −1,004.91±1.60 | 15.37±1.36 | 7.32±0.71 | 74.35±6.52 |
| DLIR-M | 131.34±3.61 | 13.54±1.24 | −1,004.90±1.72 | 11.48±2.15 | 9.70±0.74 | 101.25±18.17 | |
| DLIR-H | 130.73±4.88 | 9.02±2.11 | −1,004.90±1.03 | 6.87±0.46 | 15.00±0.22 | 165.72±11.06 | |
| 30%ASIR-V | 135.30±2.15 | 77.84±9.19 | −984.25±3.60 | 51.09±5.16 | 1.76±0.22 | 22.06±2.21 | |
| 50%ASIR-V | 135.73±11.27 | 77.65±25.70 | −988.34±1.22 | 45.21±3.97 | 1.88±0.61 | 24.99±2.27 | |
| 80%ASIR-V | 137.77±5.41 | 49.04±29.64 | −994.82±3.60 | 35.75±4.30 | 3.46±1.62 | 32.01±4.09 | |
| FBP | 146.16±12.18 | 108.91±18.26 | −976.30±5.48 | 62.70±6.38 | 1.36±0.19 | 18.02±1.74 |
SNs, solid nodules; SD, standard deviation; SNR, signal-to-noise ratio; CNR, contrast-to-noise ratio; FBP, filtered back projection; ASIR-V, adaptive statistical iterative reconstruction; DLIR-L/M/H, deep learning image reconstruction-low/medium/high.