Siemens LSO PET Detector Block (TruePoint / mCT)
Siemens' PET detector block architecture across the Biograph TruePoint era (Biograph 16 / 40 / 64) and carried into the analog-ToF Biograph mCT generation. LSO (Lutetium Oxyorthosilicate) crystals, 4.0 × 4.0 × 20 mm, 169 crystals per detector block. LSO was an early Siemens commitment; faster scintillation decay than BGO supports the tight coincidence-timing window needed for Time-of-Flight reconstruction on ToF-capable variants.
Fits
- Siemens Biograph 16 (TruePoint)
- Siemens Biograph 40 (TruePoint)
- Siemens Biograph 64 (TruePoint)
- Siemens Biograph mCT
Specs
- LSO crystals, 4.0 × 4.0 × 20 mm
- 169 crystals per block
- 144 detector blocks on base TruePoint (192 with TrueV option)
- Transaxial FOV 605 mm · axial FOV 162 mm base / 216 mm TrueV
- ToF ~540 ps on TruePoint, ~527 ps on mCT
Diagnosis
- Block dropout — individual detector block fails; results in localized sensitivity loss. Identifiable on daily PET QC.
- Timing drift — ToF-specific failure mode; affects coincidence-window resolution. Results in reduced effective ToF gain.
- Crystal damage — rare but physically possible (mechanical shock to detector housing). Energy-spectrum analysis per block identifies affected crystals.
- Uniformity drift — normalization scan catches it; periodic recalibration normalizes.
Replacement
Block-level replacement. Siemens OEM service typical. Post-swap calibration including energy normalization, uniformity, and (on ToF-capable units) coincidence-timing calibration is mandatory.