Table 1 CT values, noise and SNR of different organs and tissues in the TNC and VNC images

33.66 ± 6.69

32.68 ± 9.29

0.357

55.34 ± 6.29

56.89 ± 5.29

0.172

47.36 ± 3.30

48.35 ± 4.00

0.165

31.16 ± 2.94

28.48 ± 3.95

 < 0.05

40.49 ± 4.59

40.24 ± 5.49

0.778

49.23 ± 4.53

47.13 ± 3.86

0.004

 − 110.24 ± 12.93

 − 99.63 ± 7.12

 < 0.05

9.64 ± 1.61

9.62 ± 2.64

0.449

8.33 ± 1.22

8.14 ± 1.68

0.288

8.74 ± 1.43

8.09 ± 1.76

0.018

9.13 ± 1.60

8.80 ± 1.87

0.313

10.25 ± 1.74

10.26 ± 1.92

0.974

10.97 ± 1.96

10.11 ± 1.92

0.040

7.07 ± 1.62

6.96 ± 1.93

0.043

3.56 ± 1.03

3.67 ± 1.61

0.579

6.89 ± 1.34

7.41 ± 1.37

0.079

5.54 ± 1.01

6.35 ± 1.67

0.009

3.51 ± 0.66

3.38 ± 0.95

0.091

4.07 ± 0.73

4.07 ± 1.18

0.656

4.64 ± 0.96

4.84 ± 1.07

0.389

 − 16.54 ± 3.73

 − 15.50 ± 4.21

0.113