First Commercial PET / CT (2001)
1998 — David Townsend (University of Pittsburgh) and colleagues demonstrate the first PET / CT prototype, integrating a CT scanner with a PET ring on a shared patient couch. 2001 — Siemens (then CTI / Siemens) ships the first commercial PET / CT system, the biograph. The hybrid architecture rapidly becomes the clinical standard, and standalone PET-only is almost completely retired within a decade.
Why PET / CT changed oncology imaging
PET-only imaging gave functional / metabolic information but limited anatomic localization — radiologists frequently couldn't tell which structure an FDG-avid lesion was in. PET / CT pairs:
- CT for anatomic reference and attenuation correction (using the CT data to correct for tissue absorption of 511 keV photons in the PET reconstruction).
- PET for the molecular signal — tracer uptake mapped to anatomy.
The combination is more than additive: CT-based attenuation correction is faster and more accurate than the older transmission-source-based method, and the unified workstation reading enables fused interpretation that drove rapid adoption in oncology.
Adoption timeline
- 2001 — first commercial PET / CT (Siemens biograph).
- 2002–2005 — GE, Philips, and Siemens all launch hybrid PET / CT lines; standalone PET shipments collapse.
- 2006 — Philips Gemini TF — first ToF (time-of-flight) PET / CT.
- 2010s — TrueV-class extended axial FOV (~25 cm) becomes standard; iterative reconstruction (Q.Clear, OptisoHD).
- 2014 — Philips Vereos — first commercial fully digital (SiPM) PET / CT.
- 2018 — total-body PET / CT (UIH uEXPLORER) reshapes the top end with ~194 cm axial FOV.
Clinical impact
- Oncology staging and restaging — FDG PET / CT becomes the standard for staging lung, lymphoma, head-and-neck, esophageal, and many other cancers.
- Cardiac perfusion — Rb-82 PET / CT competes with SPECT MPI.
- Theranostic imaging — Ga-68 DOTATATE, Ga-68 PSMA, and Lu-177 follow-up imaging built on the PET / CT platform.
- Quantitative imaging — SUV (standardized uptake value) measurements become routine.
Descends to
- PET / CT
- PET / MR
- GE Discovery 690
- GE Discovery MI (digital)
- Siemens Biograph mCT
- Siemens Biograph Vision
- Philips Gemini TF
- Philips Vereos