PET / CT Decommissioning
End-of-life retirement of a PET / CT scanner. Combines the CT-side decommissioning of a multi-detector CT scanner with the isotope-side decommissioning of a PET-bearing facility. PET does not produce neutron-activated materials the way therapy linacs do — there is no cool-down waiting period — but the LYSO / LSO scintillator and calibration sources need specific handling, and the NRC license file is the load-bearing document.
PET-specific considerations
- LYSO / LSO crystals — lutetium-yttrium oxyorthosilicate scintillator is naturally weakly radioactive because of Lu-176 (2.6% natural abundance, half-life ~3.8×10¹⁰ years). Activity per crystal is very low but detectable on sensitive instrumentation. Disposal per local radioactive-material regulations; some manufacturers offer take-back programs.
- SiPM arrays (current-generation digital PET — Vision, Discovery MI, Vereos) — silicon photomultiplier tiles. Not radioactive, but high-precision electronics with refurb / parts value where module-level swap markets exist. See Discovery MI SiPM module and Siemens LSO PET detector.
- PMT arrays (legacy LSO / LYSO platforms — Discovery 690, Biograph 64 / mCT, Gemini TF) — photomultiplier tubes with trace materials requiring proper recycling.
- Ge-68 rod sources / cylinders — calibration sources used for daily QC and normalization. Decay-in-storage before disposal — Ge-68 half-life is ~271 days; ~3 years of storage drops activity below typical release limits. Then dispose as radioactive waste via licensed broker. Source removal and transfer is a documented chain-of-custody event.
- Sealed reference sources — point sources for daily QC, well-counter sources. Vendor return or licensed disposal.
- Activation — PET annihilation photons (511 keV) do not produce material activation. No cool-down waiting period. Release is administrative once contamination surveys are clean.
CT side
Same CT decommissioning workflow as a standalone scanner:
- Tube, HV generator, DAS / detector, gantry, couch, console.
- Tube and detector recovery for refurb if scan-counts are low.
- See CT decommissioning for the full workflow.
Hot lab and isotope facility
- Full nuclear-safety decommissioning if an on-site hot lab existed for FDG / Rb-82 / theranostic isotope handling. See Nuclear Medicine decommissioning for the parallel workflow.
- Rb-82 generator — Sr-82 / Rb-82 generators (CardioGen-82, RUBY-FILL) returned to vendor at end of generator life as part of the routine cycle; final-program disposal handled the same way.
- Cyclotron (if on-site, rare) — separate decommissioning event with its own activation and shielding-survey footprint, vendor-led.
- Drain monitoring — sinks and drainage have historical Tc / F-18 / Ga-68 contamination potential; sample and document.
NRC / Agreement-State license
- License amendment or cancellation at program closure. Final survey, inventory reconciliation, RSO-signed closeout.
- Authorized User physician affiliations updated.
- Records retention — license file and survey records retained per NRC requirements.
Data sanitization
- HDDs / SSDs on the scanner host, reconstruction engine, and console workstation destroyed or certified-erased per HIPAA.
- syngo.via / AW Server / IntelliSpace patient-data archive migrated.
- Modality AE titles and PACS credentials revoked.
Resale and parts recovery
- Recent-generation digital PET (SiPM) with current software has meaningful refurb interest in academic / international markets.
- PMT-era LSO / LYSO PET (Discovery 690, Biograph 64 / mCT) is a value-tier refurb category.
- CT side has its own resale path (see CT decommissioning).
- Block detector modules — high-value parts for active aftermarket programs.
Operational reality
- Hot-lab closeout runs in parallel with scanner removal and is the longer of the two paths in most decommissionings.
- Generator-source disposal timing may extend the file by months when Ge-68 decay-in-storage is required.
- Theranostic-program co-residency — sites doing Lu-177 dosimetry on the same camera face deeper isotope-side closeout than imaging-only PET.