STERILE R
STERILE R (Radiation Sterilisation) labels medical devices rendered sterile by ionising radiation: gamma radiation (Cobalt-60 sources), electron beam (E-Beam), or X-ray.
The process is governed by ISO 11137-1 to ISO 11137-3. Radiation sterilisation routinely achieves a sterility assurance level (SAL) of 10⁻⁶ and is widely used for pre-packaged single-use products because no post-sterilisation degassing is required.
Unlike ethylene oxide sterilisation (STERILE EO), radiation leaves no chemical residues in the product. However, certain materials – specific plastics and polymers – may become brittle or discoloured under radiation exposure, so material compatibility must be validated.
The STERILE R symbol per ISO 15223-1 distinguishes radiation-sterilised products from steam-sterilised (STERILE) and EO-sterilised (STERILE EO) products.
The minimum absorbed dose is set by the manufacturer based on bioburden levels and the required SAL, and must be periodically audited.
Frequently asked questions
Why does radiation sterilisation leave no residues?
Ionising radiation kills micro-organisms by damaging their DNA without using chemical agents. No degassing phase is required and no measurable residues remain in the product.
What is the difference between STERILE R, STERILE EO, and STERILE?
STERILE = steam sterilisation (autoclaving). STERILE EO = ethylene oxide, requires degassing. STERILE R = ionising radiation, no residues, no degassing step. All three achieve SAL 10⁻⁶ with validated processes.
Are all materials suitable for radiation sterilisation?
No. Some plastics, silicones, and polymers may become brittle, discoloured, or lose mechanical properties under ionising radiation. Material compatibility must be demonstrated during validation per ISO 11137.