Oncology imposes some of the heaviest and most demanding building-systems loads in a hospital: linear-accelerator (LINAC) vaults are massive concrete structures, treatment and imaging equipment draws large and tightly-conditioned electrical service, and that same equipment rejects heat that must be carried away continuously to keep beams stable and patients safe. This article covers the structural, HVAC/mechanical, electrical/power, and equipment-cooling engineering for cancer-center spaces. Radiation shielding mass is engineered by a physicist and is treated as a sibling chapter; this article addresses the structural, mechanical, and electrical disciplines that surround and support that shielding, and the heat and power those machines generate.

The engineering envelope is set by a few very heavy, very precise machines

Most of an oncology building is ordinary outpatient construction — exam rooms, infusion bays, offices, waiting. The extraordinary engineering concentrates around a handful of equipment items, and the entire structural/MEP design is driven by their vendor requirements:

• Linear accelerators (LINACs) — the treatment machines, housed in heavily shielded vaults. They are heavy, demand stable power and chilled water, and require a slab flat and stiff enough to hold sub-millimeter mechanical isocenter accuracy.
• CT simulators and diagnostic/PET-CT imaging — heavy gantries, dedicated power, and conditioned air.
• Brachytherapy afterloaders and HDR/sealed-source rooms — lighter mechanically but with their own shielding, ventilation, and interlock requirements (covered under the brachytherapy sibling).
• Pharmacy/compounding for hazardous antineoplastic drugs — negative-pressure rooms and dedicated exhaust (ventilation specifics covered under the USP <800> sibling).

Because the governing numbers (weights, electrical demand, heat rejection, chilled-water flow, clearances) come from the specific make and model selected, the cardinal rule is: design to the vendor's current planning guide, confirmed in writing, before pouring concrete or sizing equipment. Generic figures in this article are rules-of-thumb for early planning only.

Structural design is governed by equipment weight, slab flatness, and rigging paths

Structural engineering for oncology has three distinct problems: carrying the dead load of shielding and machines, achieving the flatness and stiffness the equipment needs, and getting the equipment physically into the room.

Dead load and the shielding mass. A LINAC vault is built largely of high-density concrete (and sometimes supplemental steel or composite shielding). The shielding walls, ceiling, and floor represent an enormous concentrated dead load that the foundation and any structure below must carry. Vaults are therefore preferentially located on grade or below grade (slab-on-grade or basement), which both simplifies the load path and lets earth serve as additional shielding on some faces. When a vault must sit above occupied space — common in dense urban or replacement-hospital projects — the supporting structure becomes a major, cost-driving design exercise and the structural engineer coordinates closely with the physicist's shielding report.

Slab flatness, levelness, and vibration. LINACs and imaging gantries place machine-tool-grade demands on the floor:

• The slab must meet the flatness and levelness tolerances in the vendor's planning guide (far tighter than ordinary FF/FL construction specs), often over the gantry footprint and the couch/patient-support travel.
• The slab must be stiff enough to control deflection and damped enough to control vibration, because beam targeting accuracy (isocenter) is sensitive to motion. Nearby vibration sources — mechanical rooms, elevators, transit, loading docks — must be assessed and isolated.
• Differential settlement across the vault must be controlled; some vendors specify monolithic pours, thickened slabs, or isolation joints around the machine footprint.

Embedments and penetrations. The structural and shielding design must accommodate conduit, chilled-water lines, and cable trays that pass into the vault. These penetrations are routed through the maze or as offset/dog-leg penetrations so radiation cannot stream straight through (detailed in the shielding sibling), but structurally they must be cast into the slab and walls at exact locations — late changes are extremely costly once high-density concrete is placed.

Rigging and equipment access. A LINAC and its components are too large and heavy to fit through normal doors and corridors. The design must provide a rigging path: a removable wall panel ("knock-out" or rigging opening), a temporary roof opening, or a documented route with adequate door sizes, corridor widths, turning radii, and floor load ratings from the loading dock to the vault. For replacement machines over the building's life, planners often preserve a permanent or re-openable rigging path. Floor loading along the route — and any elevator used — must be verified against the heaviest rigged piece.

HVAC keeps equipment in spec and protects vulnerable patients

Oncology HVAC serves two masters: keeping sensitive equipment within its environmental window, and protecting an immunocompromised, sometimes acutely ill patient population. The governing standards are ASHRAE 170 (ventilation of health care facilities, referenced by the FGI Guidelines) plus the equipment vendor's environmental requirements.

Equipment environmental control. LINAC vaults, CT-sim, and imaging rooms must hold temperature and relative humidity inside the vendor's stated band, typically a fairly narrow range, continuously — including overnight and on weekends, because warm-up/stabilization after an excursion can delay the treatment schedule. This usually means: