VMAT
Volumetric Modulated Arc Therapy — the gantry rotates continuously while MLC, dose rate, and gantry speed modulate simultaneously. Varian's branded variant is RapidArc; Elekta and TPS-vendor implementations are branded VMAT generically.
Why it matters to buyers: Shorter treatment time than step-and-shoot IMRT at equivalent conformality — typically 2–6 minutes per fraction. Licensed separately from hardware on some chassis. The dominant external-beam delivery technique for routine fractionation.
Why it matters to engineers: Requires MLC, dose-rate, and gantry-speed control to operate in coordinated synchrony. Drift in any of the three is a TG-142 fail.