Table 2: The CT numbers, image noise, and CNR obtained at each set of acquisition conditions.

Tube current-time product (mAs)CT number 𝑃 valueImage noise 𝑃 value*CNR 𝑃 value*
120 kV80 kV120 kV80 kV120 kV80 kV

15056.1227.56<0.0015.109.60<0.0010.890.62<0.001
20056.3427.73<0.0014.458.20<0.0011.200.79<0.001
25056.2128.17<0.0014.097.61<0.0011.460.870.006
30056.7628.35<0.0013.616.50<0.0011.731.040.029
35056.9328.21<0.0013.375.88<0.0011.951.000.025
40056.7728.41<0.0013.155.70<0.0011.971.040.028
45056.6928.43<0.0012.914.96<0.0012.111.070.031
50057.0028.36<0.0012.774.82<0.0012.291.190.042
55056.7828.68<0.0012.754.97<0.0012.211.380.224
60057.1428.78<0.0012.654.76<0.0012.331.400.272
65057.1428.86<0.0012.484.27<0.0012.471.530.501

*The 𝑃 values are those obtained with 80 kV at the 150–650 mAs settings compared with the values obtained with 120 kV and 300 mAs.