Median values of the scan parameters, signal-to-noise ratio, image-quality scores, estimated effective dose, and the percentage difference for the 2 cohorts
| Parameter | 0–4 yr | 5–9 yr | 10–16 yr | ||||||
|---|---|---|---|---|---|---|---|---|---|
| I | II | % Diff | I | II | % Diff | I | II | % Diff | |
| Tube current (mAs) | 150 | 128 | −15 | 182 | 162 | −11 | 266 | 165 | −38 |
| CTDIvol (mGy) | 7.4 | 4.4 | −41 | 8.6 | 5.5 | −36 | 20 | 7 | −67 |
| Scan length (cm) | 17.6 | 17.8 | 1 | 20.3 | 21 | 5 | 26 | 27 | 1 |
| DLP (mGy-cm) | 125 | 77 | −38 | 175 | 132 | −24 | 522 | 240 | −54 |
| ED (mSv) | 2.1 | 1.2 | −40 | 2.2 | 1.7 | −21 | 9.7 | 4.4 | −55 |
| SNR | 16.4 | 13.4 | −18 | 13.4 | 16.3 | 22 | 20.2 | 16.2 | −20 |
| IQ | 3.67 | 4.00 | 9 | 4.00 | 4.00 | 0 | 4.33 | 4.00 | −8 |
Note:—IQ indicates image quality; ED, effective dose; Diff, difference; I, baseline; II, follow-up.