systemElektaLinear Acceleratorfamily: synergy

Elekta Synergy S

Family: Elekta Synergy · Modality: Linear Accelerator

Stereotactic-focused variant of the Elekta Synergy platform. Defined by the Beam Modulator — an integrated 80-pair MLC with 4 mm leaf width at isocenter (contrast the standard Elekta MLCi 10 mm or the later Agility 5 mm). The 4 mm leaves deliver fine-aperture beam shaping for SRS and small-field stereotactic radiotherapy without the need for add-on stereotactic cones. Synergy S is Elekta's SRS-optimized Synergy-chassis platform — the Elekta counterpart to Varian TrueBeam STx / Varian Edge in positioning.

Beam Modulator MLC

  • 80 leaf pairs with 4 mm projected leaf width at isocenter — the finest MLC in the Elekta lineage when Synergy S shipped.
  • Maximum field size 16 × 21 cm — smaller than the standard Synergy's 40 × 40 cm envelope. The field-size trade-off is the price of the fine leaf resolution.
  • Leaf travel — high-speed interdigitating design supporting dynamic MLC IMRT and VMAT.
  • Clinical consequence — 4 mm leaves resolve small targets (brain metastases, vestibular schwannoma, spine SBRT) without cone swaps or auxiliary collimation.

Platform highlights

  • Synergy chassis — shared with standard Synergy. Gantry, accelerator structure, control system, XVI cone-beam CT imaging arm.
  • XVI (X-Ray Volume Imaging) — integrated kV cone-beam CT on the Synergy chassis for IGRT pre-treatment verification.
  • iView GT — EPID megavoltage portal imaging for MV verification.
  • Photon energies — typically 6 MV-only on SRS-focused configurations; some Synergy S units shipped with dual-energy configurations. 6 MV is the SRS workhorse and is often the only energy clinically required for the stereotactic use case.
  • VMAT and IMRT capable — Beam Modulator delivers dynamic MLC modulation during arc delivery.
  • Agility MLC retrofit — some late-life Synergy S have been upgraded to 5 mm Agility; others remain on the 4 mm Beam Modulator. Beam Modulator is the defining hardware of the Synergy S; an Agility-retrofitted unit is architecturally closer to a standard Synergy.

Specs

  • 6 MV photon (standard SRS configuration); dual-energy optional
  • Beam Modulator: 80-pair MLC, 4 mm leaf width, 16 × 21 cm max field
  • XVI kV cone-beam CT IGRT
  • iView GT EPID portal imaging
  • VMAT / IMRT capable
  • 100 cm SID · ±180° gantry rotation

Clinical positioning

  • Brain SRS — primary use case. Single- and multi-fraction radiosurgery to brain metastases, meningiomas, vestibular schwannomas, AVMs, functional indications.
  • Spine SBRT — fine-leaf collimation supports complex spine targets adjacent to cord.
  • Lung and liver SBRT — on motion-managed protocols.
  • Complex head-and-neck IMRT / VMAT — where fine-leaf MLC resolution improves organ-at-risk sparing.
  • Conventional radiation therapy — Synergy S can run standard treatments but the 16 × 21 cm max field may be limiting for some large-field presentations.

Service reality

  • Magnetron RF source on standard Synergy configurations (klystron on some).
  • MLC leaf service — Beam Modulator leaves are smaller and tighter-tolerance than standard MLCi 10 mm; service expertise is meaningful.
  • XVI kV cone-beam — additional service surface beyond a non-XVI linac.
  • SRS commissioning is demanding — small-field dosimetry, output factor determination at small apertures, end-to-end testing including imaging + immobilization chain.
  • TG-142 and SRS-specific commissioning per AAPM professional-society guidance (TG-142).

Market position

  • Moderate international install base. Synergy S is the Elekta SRS platform; install count is smaller than general-purpose Synergy / Infinity but meaningful at cancer centers with SRS programs.
  • Service ecosystem — Elekta OEM service; multi-vendor coverage on the Synergy chassis.
  • Successor pathway — Versa HD (Agility 5 mm MLC, FFF high dose rate, current SRS/SBRT-capable flagship); Infinity (current general-purpose flagship).

Relationship to siblings and successors

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