Electron Beam (E-Beam) processing scans products with high-energy electrons, causing ionizing radiation to permeate the product. Most commonly this radiation is used to sterilize medical devices and other products, but other specialized material modification applications (crosslinking and chain scission) are also available.

E-Beam sterilization works by scanning products with high-energy electrons. To produce these high-energy electrons, a linear accelerator takes normal grid electricity and uses radio waves to accelerate electrons to ~99.9% of the speed of light. These electrons are “scanned” up and down by a magnetic field, creating a curtain of high-speed electrons through which products are moved via conveyor.

In sterilization applications, these high-energy electrons create ionizing radiation inside the product itself, which destroys contaminant microbes by breaking apart genetic material and other molecules that these microorganisms need to grow and multiply.

The irradiation/sterilization process occurs inside a large concrete bunker, which is designed and tested to harmlessly contain the radiation produced. An automated conveyor system carries products through the treatment area. 

One of the most attractive benefits of the E-Beam process is that it can be the final step in producing sterile product: in most cases, complete cartons of products can be safely irradiated.

E-Beam sterilization ensures product safety and is environmentally friendly: no lingering radiation or dangerous residues are created. E-Beam does not carry the supply challenges associated with Gamma sterilization, nor the environmental or litigation risk associated with Ethylene Oxide (EO) sterilization. However, like EO and Gamma, E-Beam is regarded as a proven, “Established Category A” sterilization modality by the FDA. It is also highly scalable – modern E-Beam facilities process multiple truckloads of product each day.

E-Beam is very mature. The first linear accelerators were conceptualized and prototyped in the late 1920s. Johnson & Johnson introduced the first commercial E-Beam systems for medical use in 1956.

In the 1960s the technology matured, with different use cases explored in hospital radiotherapy, industrial processing, and materials science.

In the 1970s, advances in fundamental particle accelerator research in addition to modern computerized controls advanced the technology significantly in terms of total system power and reliability.

The industry has steadily produced higher energy / higher power machines with higher reliability levels. Today, machines like NextBeam’s reliably process multiple truckloads of customer products each day and benefit from exceptional reliability.

Radiation crosslinking is a process used to enhance the physical properties of polymers by creating covalent bonds between their molecular chains. This is achieved by exposing the polymer to high-energy radiation: in this case from an E-Beam system. The radiation generates free radicals (ions that are highly reactive/unstable) within the polymer structure, which then react to form crosslinks between the polymer chains, delivering improved material performance. Keep reading “E-Beam Crosslinking – A Basic Guide“.

NextBeam can help with this assessment. With some basic information about the product’s packaging configuration and dose requirements, we can quickly assess whether your product is E-Beam compatible and, if so, how efficiently it may be processed. At a minimum, testing will include dose mapping to ensure that the product can be processed within the required dose range. However – the dose mapping process is typically quick and low cost.

The microbiology testing is very similar to that performed for gamma sterilization and is comprised of bioburden recovery, bioburden enumeration, bacteriostasis/fungistasis, and a dose audit. In most cases it is possible to leverage historical testing for some of the microbiology tests. If testing is required, we can assist with defining the appropriate procedures, test methods, sample sizes, and acceptance criteria.

Regulatory activity for changing sterilizers or sterilization methods can vary based on the device type and where the device is marketed. In the United States, E-Beam is considered an “Established Category A” method, defined by a long history of safe and effective use in the industry, that may reduce or eliminate the need for regulatory notifications or submissions.

NextBeam can help with this assessment. With some information about the product materials, packaging configuration, and dose requirements, we can provide input about E-Beam as potential fit for your product. At a minimum, testing will include dose mapping to ensure that the product can be processed within the required dose range. If the product has not been qualified in radiation, max dose testing must also be carried out.

The microbiology testing is very similar to that performed for EO sterilization, comprised of bioburden recovery, bioburden enumeration, bacteriostasis/fungistasis, and fractional treatment to evaluate bioburden resistance. In most cases it is possible to leverage historical testing for some of the microbiology tests. If testing is required, we can assist with defining the appropriate procedures, test methods, sample sizes, and acceptance criteria.

Happily, EO sterilization validations are typically more complex that E-Beam validations: E-Beam validations do not require the validation of multiple process stages of preconditioning, gas exposure, and aeration. There are no lethal chemicals involved, and no need to test for residuals. 

Regulatory activity for changing sterilizers or sterilization methods can vary based on the device type and where the device is marketed. In the United States, the FDA regulates these changes but has provided guidance

A typical timeline for an electron beam sterilization validation is about 8 weeks from the time that samples are final-packaged and ready for testing.

At NextBeam we recommended prioritizing dose mapping and max dose testing as a first step in a new E-Beam sterilization validation: these are low cost and relatively fast processes that can significantly de-risk the validation process early.

The most common method of sterilization validation is VDmax, which will typically use the following sample sizes:

• 3 lots of 10 – bioburden enumeration test
• 3 to 5 units – bioburden recovery
• 3 to 6 units – bacteriostasis / fungistasis
• 2 sets of 10 units – dose audit

A typical procedure for VDmax sterilization validation would work as follows:

1. Irradiate the bioburden recovery and bacteriostasis samples. After irradiation, send these samples to the microbiology lab for bioburden recovery and B&F test, respectively.
2. After bioburden recovery test is complete, test the 3 lots of 10 samples for bioburden enumeration.
3. Using the bioburden enumeration data, determine the verification dose to be used for the dose audit from the tables in ISO 11137-2 (15 or 25 kGy) or ISO 13004 (17.5 – 35 kGy).
4. Irradiate 10 devices for the dose audit, then send them to the microbiology lab for a test of sterility.
5. Depending on the results of the dose audit, testing may be concluded, or it may be necessary to irradiate the second set of 10 dose audit samples.

Electron beam works best for low density materials up to about 0.2 grams per cubic centimeter. It may be possible to process higher density materials depending on the packaging configuration.

Subject to specific quality requirement constraints, NextBeam can help clients to optimize product configuration for maximally efficient E-Beam processing.

This depends on the product. For medical devices in the United States, quality requirements are defined by the Quality System Regulation (QSR), 21 CFR Part 820. Other quality systems can include ISO 13485 or ISO 9001.

The standards used for defining, validating, and routinely monitoring electron beam sterilization processes from a technical perspective include a wide variety of documents – based on what is being sterilized – including the ISO 11137 series and ASTM E61 documents.

Electron beam technology is extremely safe and environmentally responsible. As compared to gamma irradiation, there is no use or production of radioactive material, nor is there any risk of radiation escaping the concrete bunker. Additionally, unlike ethylene oxide sterilization, E-Beam technology does not require nor produce large quantities of toxic/carcinogenic chemicals.