Guidelines for CT-Based Transmission Imaging
| CT parameter | General principle | Effect on patient dose |
| Slice collimation | Collimation should approximate slice thickness of PET (e.g., 4–5 mm) | No effect |
| Gantry rotation speed | Slower rotation helps blur cardiac motion (e.g., 1 s/revolution or slower) | Increased radiation with slower gantry rotation |
| Table feed per gantry rotation (pitch) | Pitch should be relatively high (e.g., 1:1) | Inversely related to pitch |
| ECG gating | ECG gating is not recommended | Decreases without ECG gating |
| Tube potential | 80–140 kVp is used, depending on manufacturer specification | Increases with higher kVp |
| Tube current | Because scan is acquired only for attenuation correction, low tube current is preferred (10−20 mA) | Increases with higher mA |
| Breathing instructions | End-expiration breath-hold or shallow free breathing is preferred | No effect |
| Reconstructed slice thickness | Thickness should approximate slice thickness of SPECT or PET (e.g., 4–7 mm) | No effect |
Reproduced with permission from (6).