Varian Halcyon

Manufacturer: Varian · Modality: Linear Accelerator

Ring-gantry linac — a different architecture from the conventional TrueBeam C-arm linac. The gantry rotates inside a fixed bore (CT-like appearance), not around a fixed isocenter like a conventional linac. 6 MV flattening-filter-free only (no electron modes, no 10/15/18 MV).

What Halcyon trades away

No electron beams — limits to photon-only treatment
No conventional 10 / 15 / 18 MV — 6 MV FFF only, less penetrating than premium linacs
No MLC-independent motion management

What Halcyon gains

Simplified clinical workflow — CT-like gantry geometry is visually intuitive for techs transitioning from diagnostic CT
Fast daily CBCT — integrated + fast; reduces treatment-fraction room time
Shorter commissioning — fewer energies + simpler beam data
Smaller footprint — fits in tighter vault configurations
Lower capital cost — simpler architecture, streamlined build

Clinical positioning

Aimed at community + emerging-market centers that need a capable linac for routine IMRT/VMAT workloads — prostate, breast, H&N, routine palliation — but don't need SBRT-tier dose rates or electron treatments. Not a replacement for TrueBeam / Edge in complex practices; a complement or a first-linac install.

Specs

6 MV FFF photons only
800 MU/min dose rate
SmartBeam MLC
Integrated kV CBCT
100 cm SID (same as conventional linacs)
HyperArc (Edge-class SRS option on newer Halcyon)

Competing architectures

Closest architectural analog: TomoTherapy (ring gantry, helical delivery). Halcyon delivers in conventional IMRT/VMAT paradigm; TomoTherapy delivers helically.