CT, MRI and PET scanner manufacturing

Computed tomography scanners are assembled around a rotating gantry carrying an X-ray tube and a detector arc of thousands of scintillator or, in the newest machines, cadmium telluride photon-counting elements; MRI systems around a superconducting magnet wound from niobium-titanium and cooled by liquid helium, with gradient coils and radiofrequency electronics; PET/CT around rings of lutetium-based scintillator crystals coupled to silicon photomultipliers. Siemens Healthineers builds CT in Forchheim and MRI in Erlangen, Germany, and PET/CT in Knoxville, Tennessee; GE HealthCare builds CT and PET in Waukesha, Wisconsin, and MRI in Florence, South Carolina, and makes the PETtrace cyclotron in Uppsala; Philips builds MRI in Best, in the Netherlands, and CT in Haifa, Israel; Canon Medical (the former Toshiba Medical) in Otawara, Japan; and United Imaging in Shanghai, which built the first total-body PET scanner with the University of California, Davis. The scanners then need siting, shielding, acceptance testing and service contracts, and their software is regulated as a medical device.

Supply constraints are in the components. Helium shortages in 2022 and 2023 pushed makers toward sealed low-helium magnets (Philips BlueSeal, Siemens' sub-litre designs); lutetium oxyorthosilicate crystals and photon-counting detectors come from few sources; and X-ray tubes are made by the scanner companies and a small number of independents. Chinese makers now supply a large share of the domestic market, and the access gap in imaging tracks the radiotherapy gap. Recalls of scanners and their software are recorded in the FDA device recall database and national equivalents and are cited here only as a class. The image-guidance systems on linacs and the PET tracers that feed these scanners have their own records.