Plan linear accelerator vault construction with a Gantt chart. Track shielding design, state approval, accelerator installation, and first patient timelines.
Radiation therapy facility construction is among the most technically demanding — and most consequential — medical construction projects in healthcare. A linear accelerator vault is not simply a specialized room. It is a radiation shielding structure that must protect adjacent occupants from ionizing radiation, a precision-engineered space sized and configured for a 50,000-pound machine producing X-ray beams up to 25 million electron volts, and a state-regulated facility that cannot treat a single patient until a medical physicist has verified every beam parameter and a state radiation control program has approved the facility.
Get the Gantt chart wrong on a radiation therapy facility and you face one of three outcomes: the vault is built but doesn't pass the radiation survey, requiring expensive remediation; the accelerator is purchased but has nowhere to go because the building isn't ready; or the first patient appointment is scheduled before the physicist has completed commissioning. None of these outcomes is acceptable.
This guide walks through every phase of radiation therapy center construction and how to build the Gantt chart that keeps them sequenced correctly.
Radiation therapy facility planning begins with physics, not architecture. The equipment selection — which linear accelerator model, how many treatment vaults, what imaging modalities — drives the shielding design, which drives the structural engineering, which drives the architectural design. Get this sequence backwards and you're redesigning after you've broken ground.
Key planning decisions:
Linear accelerator selection:
Number of vaults: A single-vault cancer center is viable for low-volume programs. Most full-service radiation oncology departments target 2–4 vaults to maintain throughput if one machine is down for service.
Imaging and special capabilities: On-board imaging (CBCT) is now standard on all modern linacs. IGRT (Image-Guided Radiation Therapy) and IMRT (Intensity-Modulated Radiation Therapy) are baseline capabilities. SRS/SBRT capability adds frameless radiosurgery to the clinical program.
Staffing plan: A radiation therapy program requires: radiation oncologists, medical physicists (a board-certified physicist is required for clinical practice), radiation therapists (RTTs), dosimetrists, and oncology nurses. Physicist availability is a national shortage — hire early.
The shielding design is the foundation of the entire project. It must be completed by a board-certified radiation oncology physicist or a medical health physicist — this is not a task for the structural engineer working from a textbook formula.
Shielding design inputs:
Shielding design output:
For a typical 6 MV linac:
For high-energy 18 MV linacs:
Maze design: The entry to the vault uses a maze configuration — an L-shaped or dog-leg corridor — rather than a direct door. The maze eliminates the line-of-sight radiation path to the entry, dramatically reducing secondary barrier requirements at the door and allowing a lighter (but still very heavy) vault door. The maze geometry must be designed to meet scatter radiation limits at the door location.
Every state has a radiation control program that must review and approve vault construction plans before construction begins. This is a non-negotiable regulatory requirement — no state will allow a radiation therapy vault to operate without this approval.
Required submittal documents:
Review timeline: 30–90 days depending on state workload. Some states (California, New York, Texas) have dedicated radiation control programs with faster review; smaller states may have 60–90 day backlogs.
Gantt dependency: State plan approval must be received before the vault walls can be poured. This is a hard dependency — pouring concrete before approval risks having to tear it out. Structure your Gantt chart so state submittal occurs as soon as shielding design is complete (month 4–5), and construction cannot begin until approval is received (month 6–8).
Vault design involves design elements not found in any other medical construction:
Vault interior dimensions:
Primary door:
Penetrations through shielding:
HVAC considerations:
Treatment control area:
Patient support areas:
Vault construction is specialized concrete work. The primary barriers require:
Concrete specifications:
Construction sequence for a vault:
Radiation shielding inspection: A physicist should inspect the vault during construction — verifying wall thicknesses, penetration offsets, and maze geometry — before concrete is enclosed. Discovering a shielding error after the roof slab is poured means chipping concrete.
Linear accelerator installation is performed by the manufacturer's service team. The manufacturer schedules their team based on production and delivery logistics — the facility has limited control over the exact installation date.
Installation sequence:
Gantt milestone: Accelerator installed mechanically complete
Commissioning is the longest post-installation phase and the one most often squeezed when project teams are anxious to see the first patient. Do not compress it.
Acceptance testing: Performed by the manufacturer's physicist with the facility's physicist present. Verifies the machine meets its published specifications: output calibration, beam flatness and symmetry, field size accuracy, isocenter coincidence, imaging accuracy.
Machine commissioning: Performed by the facility's medical physicist. Per AAPM TG-142 (quality assurance standard for linear accelerators) and TG-40:
End-to-end testing: Full-system test using an anthropomorphic phantom (simulated patient). A treatment plan is created on the CT scan of the phantom, delivered on the linac, and measured dosimetrically to verify end-to-end system accuracy.
State radiation survey: Before the first patient, the state radiation control program must perform an on-site radiation survey verifying shielding performance. The physicist provides radiation measurements at all primary and secondary barrier locations. The state issues a license or certificate of registration before clinical operation begins.
Timeline: Commissioning typically takes 2–4 months for a single vault.
The radiation therapy facility Gantt chart has two hard external constraints that structure everything else:
Build your Gantt around these two fixed regulatory gates, then work forward from planning and backward from first patient to determine whether your timeline is achievable.
Key tracks to include:
Flag the critical path explicitly: shielding design → state approval → construction → installation → commissioning → state survey → first patient. Any delay in this sequence delays the program.
Radiation therapy facilities demand exactly the kind of rigorous, dependency-aware project planning that a Gantt chart provides. The shielding physics must drive the architectural design, the state approval must precede concrete, and commissioning must be protected from the pressure to see the first patient.
Build your radiation therapy center Gantt chart at gantt-chart.io. Give the medical physicist their own track, give the state review its own track, and protect the commissioning timeline — because a linear accelerator that hasn't been properly commissioned is a machine that shouldn't be treating patients.