For single-slice scanners, the same CT parameter settings should be applied for scanning the patient and the radiographic guide. The field of view, however, can be different.
For multi-slice scanners, the CT parameter settings for scanning the patient can also be applied for scanning the radiographic guide. However, for scanning the radiographic guide, a thinner slice thickness and a smaller reconstruction interval (half of the slice thickness) can be considered as the patient’s radiation dose is not affected during the scan of the radiographic guide.
A generic CT protocol for single slice scanners, multi-slice scanners, and cone-beam scanners, is provided below. This protocol is only a recommendation and should be tailored to the (CB)CT scan equipment to be used.
| Scan Settings | |
| Spiral CT | |
| No gantry tilt | |
| Tube voltage | 120 kV |
| Effective tube current | 100 mAs |
| Collimation | 1 mm |
| Table speed | 1 mm / rotation |
| Gantry rotation speed | 1 rotation / s |
| Reconstruction Settings | |
| Reconstruction interval | 0.5 mm |
| Reconstruction kernel | A sharp bone filter is preferred |
| Scan Settings | |
| Spiral CT | |
| No gantry tilt | |
| Tube voltage | 120 kV |
| Effective tube current | 90 mAs |
| Collimation | For patient: (number of detectors x) detector width 1 mm or smaller For radiographic guide: (number of detectors x) smallest detector width (mm) |
| Feed per rotation | Collimation x 0.7 |
| Gantry rotation speed | ± 0.75 rotation / s |
| Reconstruction Settings | |
| Reconstruction interval | Half detector width (for patient typically 0.5 mm; for radiographic guide typically 0.5 mm or smaller) |
| Reconstruction kernel | A sharp bone filter is preferred |
Cone-beam CT scanners are dedicated for imaging the skull. Follow the manufacturer’s instructions to scan a jaw and the radiographic guide for oral implant planning.
The size of a cubic voxel should be within the range of 0.25 – 0.5 mm. During reconstruction, no tilting of the axial slices is allowed.