Linac, proton system and brachytherapy machine manufacturing

A medical linear accelerator is a factory product: a waveguide and magnetron or klystron, a bending magnet and target, a multileaf collimator with over a hundred motorised tungsten leaves, kilovoltage and megavoltage imaging panels, a treatment couch and the control and record-and-verify software, assembled and tested over weeks and then installed in a shielded bunker and commissioned by physicists for months. Varian (part of Siemens Healthineers, headquartered in Palo Alto with manufacturing there and in Beijing) and Elekta (Stockholm, with its linac factory in Crawley, England, and a plant in Beijing) build most of the world's linacs; Accuray builds TomoTherapy and Radixact in Madison, Wisconsin, and CyberKnife, with a joint venture in Chengdu for the Chinese market; Chinese makers such as Shinva and United Imaging are growing at home. Elekta's Unity and ViewRay's MRIdian created the MR-linac category, and RefleXion adds PET guidance. Brachytherapy afterloaders come from Elekta (Flexitron) and Varian (BRAVOS), with iridium-192 and cobalt-60 sources from a few source makers; cobalt-60 teletherapy units, still important where linacs cannot be serviced, come from Best Theratronics in Ottawa.

Proton and heavy-ion systems are a separate industry of cyclotrons and synchrotrons, gantries and pencil-beam scanning nozzles: IBA in Louvain-la-Neuve (the largest installed base), Hitachi in Japan, Varian's ProBeam built in Troisdorf, Germany, Mevion's single-room synchrocyclotron in Littleton, Massachusetts, Sumitomo Heavy Industries, ProTom, and newer upright-treatment designs from Leo Cancer Care and P-Cure. Supply constraints are less about factory volume than about capital cost, bunkers, trained physicists and service networks: the IAEA's DIRAC directory shows most low-income countries with a handful of megavoltage machines or none, a gap covered in the radiotherapy access record. Machine and software recalls are published in the FDA device recall database and equivalent national registers, and are recorded here only as a class.