Table 1.
Characteristics of the Discovery MI and Gemini TF PET-CT systems
| PET-CT system | Discovery MI | Gemini TF |
|---|---|---|
| Crystal material | LYSO | LYSO |
| Amplifier | SiPM | PM-tubes |
| Number of rings | 4 | 3 |
| Size of crystals [mm3] | 3.95 × 5.3 × 25 | 4.0 × 4.0 × 22 |
| Axial FOV [mm] | 200 | 180 |
| Bore diameter [mm] | 700 | 700 |
| Overlap [%] | 23.9 | 50 |
| NEMA Sensitivity [cps/kBq] | 13.8 | 7.0 |
| FWHM axial @1 cm [mm] | 4.7 | 5.8 |
| Coincidence window width (ns) | 4.9 | 6 |
| Timing resolution (ps) | 382 | 600 |
| Lower energy threshold (keV) | 425 | 440 |
| Matrix | 256 × 256 | 144 × 144 |
| Pixel size (mm2) | 2.7 × 2.7 | 4.0 × 4.0 |
| Slice thickness [mm] | 2.79 | 4.0 |
| Image planes in the axial FOV | 71 | 45 |
| Number of CT slice | 128 | 16 |
FOV field of view; FWHM full width at half maximum; LYSO lutetium-yttrium oxyorthosilicate; NEMA National Electrical Manufacturers Association; PM photomultiplier; SiPM silicon photomultiplier