systemGE HealthCarePET CT

GE Discovery PET/CT 690

Manufacturer: GE HealthCare · Modality: PET/CT · Production: 2011–present

Premium analog PET/CT combining a 24-ring LYSO PET detector (13,824 crystals) with Time-of-Flight and a 64-slice CT derived from the LightSpeed VCT. The last major generation of GE PET/CT before the digital SiPM transition to Discovery MI; still in OEM service and the backbone of a large share of US outpatient oncology PET/CT volume.

PET detector architecture

  • LYSO crystals (lutetium yttrium oxyorthosilicate) — fast scintillation and high stopping power, ToF-capable.
  • Crystal geometry — 4.2 × 6.3 × 25 mm per crystal, 54 crystals per block, 64 blocks per ring, 24 rings.
  • 13,824 crystals total across the full detector ring.
  • Time-of-Flight — ~500 ps timing resolution. Analog PMT-based coincidence timing rather than the digital SiPM approach used on Discovery MI and Biograph Vision. Materially less ToF precision than current digital platforms, still a meaningful image-quality improvement over non-ToF predecessors.
  • Axial FOV — 15.7 cm.

CT architecture

The CT side is a rebadged LightSpeed VCT:

  • 64 slices, 70 cm gantry aperture.
  • Performix Pro VCT 100 tube (8.0 MHU heat capacity) — same tube as VCT XT.
  • ASiR iterative reconstruction on supported configurations.
  • Internal gantry cooling — no external chiller required for the integrated PET/CT gantry, a meaningful site-requirements and service difference vs the standalone VCT.

Calibration and regulatory

  • Ge-68 rod sources — automated daily PET calibration.
  • NRC / Agreement State licensing required for the radioactive sources on-site; Radiation Safety Officer and source disposal path must be in place (NRC licensing).
  • MAUDE, FDA 510(k) history — Discovery 690-class PET/CT has a mature clearance and event history per the FDA 510(k) and MAUDE datasets.

Clinical positioning

  • Oncology FDG — workhorse FDG staging / restaging / response imaging.
  • Cardiac rubidium (Rb-82) — myocardial perfusion PET at centers with an onsite generator.
  • Neuro PET — amyloid imaging, FDG dementia workup.
  • Theranostic imaging — ⁶⁸Ga-DOTATATE, PSMA PET at centers that adopted before Discovery MI replacement.

Service reality

  • PET detector parts ecosystem is ToF-specific and not interchangeable with Discovery STE / VCT BGO predecessors.
  • CT-side parts (tube, DAS, slip ring, HV generator) overlap with the LightSpeed VCT aftermarket — deep supply, mature service.
  • Cryogen-free (no helium) — PET detector doesn't require the cold-head PM discipline of MRI.
  • Radiation-source handling is the non-obvious service-and-compliance burden: daily calibration, exchange cadence, RSO oversight.

Parts

PET-specific:

Shared with LightSpeed VCT:

Field guide

See field-guide/ge-healthcare-discovery-690 — PET failure domain (crystals, PMTs, ToF timing), CT overlap with LightSpeed VCT, radiotracer handling and regulatory posture.

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