Table I.
Key data acquisition parameters for each exam type.
| Manufacturer (Scanner) | Scan parameter | Head CT for acute cognitive or motor deficit | Chest CT for lung cancer screening* | Abdomen CT for metastatic liver lesion detection |
|---|---|---|---|---|
| GE Healthcare (Discovery CT750i) | Scan geometry | Axial and Helical | Helical | Helical |
| Contrast enhanced | No | No | Yes | |
| Manual tube current (mA) | 300 | – | – | |
| Noise index for Smart mA | – | Variable based on patient size, tube potential, and thickness of first image series reconstructed | ||
| Tube potential (kV) | 120 | 80 – 120 | 80 – 120 | |
| Rotation time (s) | 1 | 0.5 | 0.5 | |
| Mean CTDIvol (mGy) | 56.8 | 6.4 | 12.2 | |
| Siemens Healthineers (SOMATOM Definition AS+, SOMATOM Definition Flash) | Scan geometry | Helical | Helical | Helical |
| Contrast enhanced | No | No | Yes | |
| Manual effective tube current time product (effective mAs) | 250 | – | – | |
| Quality reference mAs for CareDose4D | – | 70 | 200 at reference of 120 kV | |
| Tube potential (kV) | 120 | 120 | 100 – 120 | |
| Rotation time (s) | 1 | 0.28 or 0.3 | 0.5 | |
| Mean CTDIvol (mGy) | 43.7 | 6.6 | 15.6 | |
*
To provide a better ground truth, cases were collected using a chest CT protocol that used twice the radiation dose than was used in the National Lung Screening Trial.
CTDIvol = Volume CT Dose Index