Radiation Sterilization: Electrons (Beta), Gamma, and X-Rays

Aseptic process

Validation of radiation sterilization processes is an essential requirement in regulated industries such as pharmaceuticals, medical devices, and sterile cosmetics.

This process consists of ensuring that the radiation treatment achieves the microbial reduction necessary to achieve sterility (understood as SAL 10-6) without affecting the functionality, safety or integrity of the product.

In this context, we offer a specialized service of initial validation, periodic revalidation and technical review of existing sterilization processes that use Gamma radiation, Beta radiation (accelerated electrons) and X-rays, in accordance with the requirements of ISO 11137 (Parts 1, 2 and 3) and other applicable guidelines of the regulated environment.

Scope of Service
Our services are aimed at companies that need:

  • Design, validate or review a radiation sterilization process according to international standards, complying with the regulatory requirements demanded by regulatory authorities (FDA, EMA, KFDA, etc.).
  • Ensure that a robust and repeatable process is established to achieve sterility (SAL 10 -6 ) of products.
  • Ensure that the effectiveness of the radiation sterilization process is maintained throughout the life of your product.

We can advise you at all stages of the validation process:

  1. Product characterization: Technical definition of the product and product family to minimize testing and costs, and the analysis of the initial bioburden.
  2. Determination of the sterilization dose:
    • Application of statistical methods: VDmax25, Method 1 and Method 2 according to ISO 11137-2 for the determination of the sterilizing dose.
    • Establishment and functional validations of the product at the maximum dose.
  3. Microbial resistance studies and dose audit.
  4. Validation of the routine process: definition of control parameters, frequency of verification, and limits of alert and action.
  5. Maintenance of process efficacy: Annual maintenance, which includes periodic bioburden determinations and verification dose of sterilization by gamma, beta or X-ray radiation.
  6. Technical review of existing validations: assessment of regulatory compliance, weakness and documentation analysis.
  7. Support in inspections and audits: Preparation of documentation and scientific justifications in front of health authorities or customers.

Sterilization technologies covered

  • Gamma radiation (Cobalt-60): widely used for its penetrating capacity. Ideal for bulky loads or closed packaging.
  • Accelerated Electrons (Beta): Offers short exposure times and precise control, although with lower penetration.
  • X-rays: emerging technology that combines good penetration with less radioactive waste generation.

You can see a comparison of radiation sterilization technologies in this article.

Applicable Standards and Guidelines
Our approach is aligned with:

Applications by industry

  • Sterile medical devices (syringes, catheters, gloves, implants)
  • Heat-sensitive medications and excipients (gels, packaging materials)
  • Single-use medical devices (swabs, gauzes)
  • Sterile cosmetics and personal care products
Shall we review your sterilization process?
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Frequently Asked Questions (FAQ)

What is radiation sterilization?
It is a physical process that uses ionizing radiation (Gamma, Beta or X-rays) to eliminate viable microorganisms present in medical, pharmaceutical or health products. It is especially useful for products sensitive to heat or moisture, where methods such as steam or ethylene oxide are not viable.
What is the difference between Gamma, Beta and X-ray radiation?
  • Gamma radiation (cobalt-60): High penetration. Ideal for dense products or large packages.
  • Beta radiation (accelerated electrons): High speed and efficiency without radioactive sources, but less penetration. Requires precise product alignment. The boxes have to be depalletized and sometimes turned over.
  • X-rays: They combine good penetration with cleaner operation (no permanent radioactive sources). They are an increasingly adopted alternative.
What is VDmax25 in sterilization?
VDmax25 is a simplified validation method set out in ISO 11137-2, designed to determine whether a dose of 25 kGy (kilograys) is suitable to ensure the sterility of a product. It is based on a statistical relationship between the initial bioburden of the product and the ability of a fixed dose to achieve a sterility assurance level (SAL) of 10⁻⁶.

This method is applicable only when the bioburden of the product is low and consistent, requires a limited number of samples for validation (typically 100 units), and involves an initial validation study and periodic dose audits to verify process stability.

Advantages of using VDmax25:
  • Lower complexity and cost compared to methods 1 and 2.
  • Suitable for mass-produced products and stable microbiological control.
  • Rapid implementation if the bioburden is known and consistently low.
What methods are there to determine the sterilization dose?
ISO 11137-2 sets out three main methods:
  • Method 1: Based on microbial resistance and minimum effective dose studies.
  • Method 2: Use more extensive statistical studies.
  • VDmax25 simplified method for certain bioburden ranges and specific conditions.
  • The choice of method depends on the type of product, production volume and regulatory requirements.
When is it required to validate a sterilization process?
Validation is mandatory in the following cases:
  • Before marketing a new product.
  • When modifying the design of the product or its packaging.
  • Change of sterilization technology or service provider.
  • After detecting deviations or failures in the routine process.
Can I outsource the sterilization validation service?
Yes. Many companies outsource this process to specialists to ensure regulatory compliance, reduce times, and avoid technical errors. Our service includes comprehensive support, from planning to reporting and audit accompaniment.