Planning a new X-ray room — whether in a new-build facility or through conversion of an existing space — is a more complex process than most clinic owners and project managers expect. The room must be designed around the radiation safety requirements, not the other way around. A beautiful, clinically functional X-ray room that fails FANR's radiation safety assessment will not receive its operating licence — and the cost of retrofitting inadequate shielding after construction is far higher than getting the design right from the beginning. This article walks through the complete radiation safety assessment process for a new X-ray room in the UAE.
The radiation safety assessment begins with a detailed technical specification of the X-ray equipment to be installed. The physicist needs:
• Equipment make, model and generation • Maximum kVp and mA • Generator power rating • Expected workload — how many exposures per week, at what technique factors • Primary beam directions — which walls will receive the direct beam • Detector type and position (wall Bucky, table Bucky, both)
Changing the equipment after the radiation safety assessment has been completed — upgrading from a 32kW to a 65kW generator, for example — requires the assessment to be repeated because the workload and output assumptions will have changed.
The most important factor in a radiation safety assessment is what is in the adjacent spaces — the rooms, corridors, offices and external areas that share walls, floors and ceilings with the X-ray room. Each adjacent area is assessed for its occupancy factor — the fraction of the working day during which it is occupied.
A staff office adjacent to the X-ray room (high occupancy, high dwell time, classified as uncontrolled area) requires significantly more shielding than an external wall facing a rarely-used car park (low occupancy, uncontrolled). The occupancy factor directly affects the lead thickness calculation.
Critical adjacencies to identify: • Is there a floor above? What is it used for? • Is there a floor below? What is it used for? • What are all four walls adjacent to? Which are internal (occupied) and which are external? • Is the control room within the X-ray room, or is the radiographer in a separate room?
Primary barriers are those in the path of the direct X-ray beam — typically the wall behind the detector (Bucky wall), the floor if the beam can be directed downward, and the ceiling if the beam can be directed upward. Primary barriers require the heaviest shielding because they intercept the full intensity of the primary beam.
Secondary barriers receive only scattered radiation from the patient and leakage from the tube housing — a fraction of the primary beam intensity. Secondary barriers require less shielding than primary barriers, but they still require calculation — the assumption that any wall not in the direct beam requires no shielding is incorrect and leads to compliance failures.
Existing walls, floors and ceilings provide some inherent radiation attenuation. A standard 200mm concrete block wall attenuates X-rays significantly — potentially equivalent to 1mm of lead at diagnostic energies. A solid brick wall provides measurable but lower attenuation. A lightweight drywall partition provides almost no radiation attenuation.
The physicist must assess the existing construction of each barrier and calculate how much additional lead — if any — is needed to bring it up to the required shielding level. Accurate construction information (wall type, thickness, density) is essential for this assessment — if it is not available, conservative assumptions must be used.
The radiation safety assessment feeds directly into the construction design:
• Where are the electrical conduits and plumbing runs? These must be routed so they do not penetrate primary barriers without lead wrapping. • Where is the light switch? If it is on a primary barrier, the lead must be continued behind the switchbox and conduit. • What is the door position? If the door is in a primary or high-scatter secondary barrier, it requires a lead-lined door. • Is there a viewing window? Its position determines the lead glass specification. • Where does the control cable or intercom run? These penetrations must be sealed with lead plugs.
The output of the radiation safety assessment is a formal shielding design report. This document — prepared and signed by the medical physicist — specifies:
• The facility and room details • The equipment specification • The workload assumptions • The adjacency analysis with occupancy factors • The calculated lead thickness for each barrier • A room diagram showing all barriers and their specified shielding • The design dose rates at each controlled point
This report is a mandatory submission document for the FANR licence application. Without it, the application cannot proceed.
Ideally, before construction begins — at the architectural design stage. This allows the shielding requirements to be incorporated into the structural design. A minimum lead time of 4 weeks before construction should be allowed for the assessment report to be completed.
Any change to room dimensions, wall construction, adjacent area use, or equipment specification after the assessment report is completed requires a reassessment. Small changes may require only a revision to the report; larger changes require a full reassessment.
RevirzaMed Healthcare Solutions — Abu Dhabi's trusted FANR Approval and medical equipment specialists since 2015.