Table 1. Scan protocol for the CT scans of the three scanners.
| S1 | S2 | S3 | |
|---|---|---|---|
| Acquisition parameters | |||
| Scan mode | Spiral | Spiral | Spiral |
| Tube voltage (kV) | 120 | 140/80* | 120 + 140/80* |
| Automatic Exposure Control | Yes | no | No |
| Exposure (mAs) | 53–129 | 168 | 101 |
| Average CTDIvol (mGy) | 9.36 | 9.66 | 9.02 |
| Rotation time (s) | 0.4 | 0.6 | 0.5 |
| Collimation (mm) | 64 x 0.625 | 64 x 0.625 | 20 x 0.2 |
| Pitch factor | 0.671 | 0.984 | 1.2 |
| Reconstruction parameters | |||
| MAR technique | O-MAR | SMAR | MARIS |
| Slice thickness (mm) | 0.67 | 0.625 | 0.6 |
| Reconstruction Index (mm) | 0.67 | 0.625 | 0.6 |
| Number of slices | 366 | 399 | 409 |
| Field of view (cm) | 25 | 25 | 25 |
S1: Philips Brilliance ICT 256, S2: GE Discovery CT 750 HD, S3: Siemens Somatom Definition AS Open, O-MAR: Metal Artifact Reduction for Orthopedic Implants, SMAR: Smart Metal Artifact Reduction, MARIS: Metal Artifact Reduction in Image Space.
* S2 scanned using dual energy. S3 used both a metal artifact reduction technique based on single and on dual energy using a tube voltage of 140/80 kV.