Table 4:

Radiation dose indices, noise, and CNR of temporal bone helical scans with different effective tube mAs

Effective mAsCTDIvol (mGy)Noise (HU)CNR
AxialCoronal
Brain StemSphenoidBrain StemAirAxialCoronal
404.2268.1110.0178.697.54.46.0
808.7191.366.4113.870.06.69.7
12013.3155.062.9102.367.88.110.7
16017.1130.362.888.859.19.312.7
20020.7105.650.282.559.811.813.1
24025.4103.445.273.851.612.315.1
28029.199.243.565.550.812.816.4
32035.288.142.560.549.914.117.2
36038.288.943.357.244.914.018.9