Table 3.
Scan Parameters and Dose Estimates
| Total (n = 1277) | 64-Slice MDCT (n = 713) | 64-Slice DSCT (n = 220) | 64-Slice DSCT: Indication-based Protocols (n = 90) | 128-Slice DSCT: BMI-based Protocols (n = 254) | P Value | |
|---|---|---|---|---|---|---|
| Scan Parameters | ||||||
| Tube voltage, kVp | ||||||
| 80 kVp, n (%) | 18 (1.4) | 1 (0.14) | 3 (1.4) | 0 (0) | 14 (5.51) | <.001 |
| 100 kVp, n (%) | 150 (11.7) | 7 (0.98) | 25 (11.4) | 6 (6.7) | 112 (44.1) | <.001 |
| 120 kVp, n (%) | 1104 (86.5) | 705 (98.9) | 188 (85.5) | 84 (93.3) | 127 (50.0) | <.001 |
| 140 kVp, n (%) | 5 (0.4) | 0 (0) | 4 (1.8) | 0 (0) | 1 (0.39) | .008 |
| RGT, n (%) | 1092 (85.5) | 713 (100) | 193 (87.7) | 66 (73.3) | 120 (47.2) | <.001 |
| ECTCM, n (%) | 344 (26.9) | 0 (0) | 178 (80.9) | 58 (64.4) | 108 (42.5) | <.001 |
| ECG-PW, % | 20.1 ± 14.2 | 0 (0) | 22.9 ± 12.7 | 21.8 ± 12.8 | 15.3 ± 15.5 | <.001 |
| PGT, n (%) | 225 (17.6) | 0 (0) | 26 (11.8) | 24 (26.7) | 175 (68.9) | <.001 |
| Axial, n (%) | 75 (5.9) | 0 (0) | 26 (11.8) | 24 (26.7) | 25 (9.84) | <.001 |
| High-pitch helical, n (%) | 150 (11.7) | 0 (0) | 0 (0) | 0 (0) | 150 (59.1) | <.001 |
| AEC, n (%) | 442 (34.6) | 0 (0) | 135 (61.4) | 86 (95.6) | 221 (87.0) | <.001 |
| Scan length, cm | 16.3 ± 2.1 | 16.3 ± 1.7 | 16.1 ± 2.6 | 15.9 ± 2.6 | 16.8 ± 2.5 | <.001 |
| Dose Estimates | ||||||
| CTDIvol, mGy | 58.1 (46.4–77.0) | 70.5 (53.4–79.1) | 56.3 (42.1–70.9) | 46.2 (29.9–61.2) | 25.9 (16.9–46.4) | <.001 |
| DLP, mGy × cm | 724.0 (552.0–1010.0) | 934.0 (664.0–1051.0) | 729.0 (543.8–988.8) | 584.0 (341.0–785.25) | 239.0 (125.3–481.8) | <.001 |
| ED, mSv | 10.4 (7.7–14.1) | 13.1 (9.3–4.7) | 10.2 (7.6–13.8) | 8.2 (4.8–11.0) | 3.3 (1.8–6.7) | <.001 |
kVp = kilovolt-potential; RGT = retrospective gating; ECTCM = electrocardiogram-based tube current modulation; ECG-PW = electrocardiogram-based pulsing window; PGT = prospective triggering; AEC = automatic exposure control;CTDIvol = volume-weighted computed tomography dose index; mGy = milligray; DLP = dose-length-product; ED = effective dose estimate; mSv = millisievert.