Table 2:

Original and dose-reduced CTDI_vol and noise values for all head protocols

Patient Age Category	Protocol	CTDIvol (mGy)			Noise (HU)
		Original	Dose-Reduced	Difference	Original	Dose-Reduced	Difference
0–23 mo	Brain	15.0 ± 0.7	8.0 ± 0.4	−47%	4.4 ± 1.0	4.2 ± 0.7	−3%
2–5 yr	Brain	24.1 ± 0.9	14.6 ± 0.6	−39%	4.2 ± 0.7	4.1 ± 0.7	−3%
6–10 yr	Brain	26.3 ± 1.3	15.9 ± 0.4	−40%	4.1 ± 0.5	4.2 ± 0.6	4%
11–18 yr	Brain	29.1 ± 0.9	17.0 ± 0.5	−42%	4.4 ± 0.6	4.5 ± 0.6	3%
≥ 19 yr	Brain	36.6 ± 0.8	18.9 ± 0.5	−48%	4.3 ± 0.6	4.4 ± 0.4	3%
0–18 yr	Maxilla	19.4 ± 0.0	11.5 ± 0.1	−41%	11.2 ± 2.8	11.6 ± 1.6	3%
≥19 yr	Maxilla	22.8 ± 0.0	18.7 ± 0.2	−18%	9.6 ± 1.4	9.2 ± 1.7	−3%
0–18 yr	Orbits	26.9 ± 8.0	15.8 ± 0.5	−41%	7.5 ± 1.2	7.2 ± 0.1	−4%
0–18 yr	Sinus	13.1 ± 0.0	7.2 ± 0.3	−45%	8.5 ± 1.2	8.9 ± 1.1	5%
≥19 yr	Sinus	22.8 ± 0.0	13.7 ± 0.1	−40%	8.3 ± 0.9	8.2 ± 0.6	−1%
2–18 yr	Temporal	40.7 ± 0.0	22.8 ± 0.0	−44%	9.3 ± 1.4	9.2 ± 1.2	−2%
≥19 yra	Temporal	49.9 ± 0.0	29.7 ± 0.0	−40%	9.3 ± 1.0

^aNo dose-reduced patient examinations were available for comparison. Dose-reduced CTDI_vol value is calculated on the basis of scan parameters. Dose difference is a theoretic calculation.