Table 2.
Mean value and standard deviation (SD) in different five ROIs with different exposure intensities (in HU).
| 50 kVp, 0.4 mA | 50 kVp, 0.6 mA | 50 kVp, 0.8 mA | 50 kVp, 1.0 mA | 50 kVp, 1.2 mA | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | Mean | SD | Mean | SD | Mean | SD | |
| Center | −18.9 | 66.1 | −18.0 | 53.9 | −18.7 | 46.7 | −18.4 | 42.2 | −16.1 | 38.0 |
| Top | 4.0 | 59.3 | 6.1 | 47.9 | 5.3 | 41.4 | 4.7 | 37.6 | 5.0 | 33.7 |
| Bottom | −0.2 | 59.9 | −0.4 | 48.3 | 0.5 | 42.2 | 1.0 | 37.3 | 1.9 | 34.7 |
| Left | −0.6 | 59.6 | −0.4 | 48.5 | 0.5 | 42.6 | 1.2 | 37.8 | 1.3 | 34.1 |
| Right | 5.5 | 59.3 | 6.6 | 47.6 | 4.9 | 41.2 | 4.7 | 36.9 | 4.8 | 33.6 |
| Average difference between center and periphery | 16.9 ± 9.8 | 16.8 ± 10.0 | 17.3 ± 9.9 | 17.0 ± 9.7 | 15.5 ± 8.8 | |||||
| Average SD | 60.8 ± 3.0 | 49.3 ± 2.6 | 42.9 ± 2.2 | 38.4 ± 2.2 | 34.8 ± 1.8 | |||||