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Philips Dual-Layer CT Detector (Sandwich Detector)

Philips' proprietary dual-layer scintillator detector — the defining hardware of Philips' spectral CT platform (IQon Spectral CT, Spectral CT 7500). The top scintillator layer preferentially absorbs low-energy photons; the bottom layer captures the high-energy remainder. Both layers are read out per view, producing simultaneous low- and high-energy data through the same projection line — architecturally different from fast-kVp-switching (GE GSI) or dual-source (Siemens Force) approaches to spectral CT. Every scan is spectral.

Fits

Specs

  • Dual-layer scintillator architecture (top layer: low-energy preferential; bottom layer: high-energy residual)
  • Per-view simultaneous dual-energy readout
  • Spectral information inherent in every acquisition — no separate protocol selection, no dose penalty for spectral mode

Diagnosis

  • Ring artifact — detector-channel level; run detector calibration.
  • Inter-layer calibration drift — dual-layer-specific failure mode; affects spectral reconstruction accuracy even when conventional-image quality appears normal. Spectral-calibration phantoms verify.
  • Material-decomposition result errors — suggest inter-layer timing or calibration issue rather than a single failed channel.

Replacement

Module-level replacement. Dual-layer calibration mandatory post-swap — more complex than single-layer-detector calibration because both spectral channels must align. Philips OEM service typical.

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