The medical linear accelerator (LINAC) is the heaviest, most schedule-critical, and most tolerance-sensitive single piece of equipment installed in a healthcare-construction project. Getting it into a shielded vault, mounting it on a structurally isolated slab, and turning it over to a clinical team is a months-long, multi-party process that bridges the end of construction and the start of clinical operations. This article covers the equipment-side lifecycle — vault readiness handoff, rigging and delivery, mechanical/electrical installation, vendor calibration, acceptance testing, and physics commissioning — and how that sequence is choreographed against the building schedule so the vault is ready exactly when the machine arrives and the machine is treatment-ready exactly when the program opens.

This is the activation-and-safety counterpart to the design-side Articles in this Part: the vault shell, maze geometry, shielding mass, and penetrations are designed and built elsewhere in the oncology "book." Here we assume a structurally complete, shielded vault and walk the machine in.

The LINAC installation sequence is a hand-off relay, not a single event

A LINAC install is best understood as a relay of distinct responsibilities, each with its own party, deliverables, and sign-off gate. Treating it as one undifferentiated "equipment delivery" line item is the most common cause of schedule slippage. The canonical sequence:

1. Vendor pre-design & physics input. Before the vault is even framed, the equipment vendor (Varian/Elekta/Accuray and similar) issues a planning/pre-installation package, and a qualified medical physicist performs the shielding design that drives the vault geometry. (Shielding design itself is covered in the vault and shielding Articles.)
2. Vault construction & turnover. General contractor builds the shielded shell; a defined vault-ready milestone hands a clean, conditioned, surveyed room to the equipment team.
3. Rigging & delivery. The crated machine is transported, lifted/rolled into the building, and set on its base.
4. Mechanical & electrical installation. Vendor field engineers assemble the gantry, stand, treatment couch, modulator, and water/air systems; the contractor's trades provide and connect utilities to defined termination points.
5. Vendor calibration & internal checkout. The vendor brings the machine to a known baseline and runs its own internal acceptance.
6. Customer Acceptance Test (CAT / acceptance testing). The physicist verifies, with the vendor, that the machine meets contractual and specification tolerances. Acceptance gates the warranty start and the title/payment milestone.
7. Physics commissioning. The physicist independently characterizes the beam, builds the beam-data model, and validates the treatment-planning system. This is the longest single sub-phase and it cannot start until acceptance passes.
8. End-to-end / clinical readiness & first patient. Independent dosimetry checks, dry-run patient workflows, and regulatory clearances close out before the first treatment.

Each arrow between steps is a gate with a named owner. The owner's matrix (vendor vs. GC vs. owner's physicist vs. AHJ) should be agreed in writing during preconstruction — see the responsibility section below.

Vault readiness is a formal milestone with a defined punch list

The single most schedule-protective practice is to define vault-ready as a contractual milestone with an explicit checklist, not a verbal "it looks done." The vendor publishes minimum environmental and structural conditions the room must meet before they will mobilize field engineers; failing to hit them on the agreed date pushes the entire downstream commissioning chain. A typical vault-ready punch list includes:

• Structural slab cured and level. The equipment base slab must reach design strength and meet the vendor's flatness/levelness tolerance (often in the range of a few millimeters across the isocenter footprint — confirm the specific machine's spec). Heavy machines on a structurally isolated/thickened slab need the concrete fully cured before the gantry is set.
• Shielding complete and verified. All concrete pours, high-density additions, lead/steel at penetrations, and the maze are in place. The physicist's pre-occupancy shielding survey logic relies on the as-built mass; any field change to penetrations or door must be reconciled before machine energization.
• Conditioned space. HVAC operational and holding the vendor's temperature and humidity band (LINACs are sensitive to thermal drift; many specs call for a tight setpoint, e.g., roughly 68–72°F with controlled humidity — confirm per model). The room must be clean, dry, and dust-controlled; commissioning hates particulate and moisture.
• Utilities terminated to spec. Dedicated power (often 3-phase) landed at the disconnect with the right capacity and grounding per NEC 517; chilled/processed water for the magnetron/klystron and modulator cooling brought to the connection point at the required flow, temperature, and quality; compressed air; and network/data pathways. Emergency power and the room's life-safety systems tie into the building's NFPA 99 / NFPA 110 essential electrical system as applicable.
• Penetrations and conduits dressed. All cable troughs, conduit sleeves, and the under-slab or wall ducts between the modulator/equipment room and the gantry are open, labeled, and baffled per the shielding design (conduits through shielding are stepped/baffled so they don't create a radiation leak path).