Electron beam sterilization (also called e-beam sterilization) uses an accelerator to fire an irradiating e-beam to inactivate microorganisms.
Electron beam sterilization — also known as e-beam sterilization — is a radiation-based method for sterilizing medical devices.
It’s one of the least-used but fastest-growing medical device sterilization methods due to its speed, effectiveness and relative safety.
E-beam sterilization could help manufacturers move away from ethylene oxide (EtO). EtO is a versatile and effective means of sterilization for a wide range of medical devices, but the FDA and leaders in the medical device industry are seeking alternatives due to the health risks of EtO emissions.
Like the other main radiation-based sterilization methods — gamma ray and X-ray — electron beam sterilization can penetrate packaging, devices and airtight compartments. E-beam sterilization is best suited to low- to medium-density products.
E-beam sterilization is used for some single-use devices, heat-sensitive devices and radiation-resistant plastic devices. Radiation damages many plastics, ranging from discoloration to embrittlement. E-beam sterilization works faster than other radiation methods, and is less likely to damage plastics.
Radiation sterilization damages semiconductors so it should not be used for medical devices with electronics.
Stents, blood products, plastic tubing and surgical components are some examples of medical devices that can be sterilized with electron beams.
How electron beam sterilization works
U.S. Department of Energy experts explained how e-beam sterilization works in a paper published through DOE’s Office of Scientific and Technical Information:
“High energy E-Beam irradiation is characterized by its highly energetic electrons (10 MeV) and higher dose rates (~ 3000 kGy/sec) than X-rays or Co-60 gamma. The beam is generated by an accelerator that produces continuous or pulsed beams of high energy electrons with an electrical current, accelerated to near the speed of light, focused to a scan horn of a defined size, and scanned in a sweeping motion, creating a curtain of electrons. The product is then conveyed through the scan curtain at a tightly controlled and measured speed. The process itself takes place behind a radiation shield, typically a large concrete structure, which prevents radiation from leaving the cell. As the product or material being sterilized passes the E-Beam, energy from the electrons is absorbed, altering various chemical bonds, damaging DNA, and destroying the reproductive capabilities of microorganisms.”
Who uses e-beam sterilization?
There are at least a dozen contract electron beam sterilization facilities in the U.S. for medical device developers.
Original equipment manufacturers (OEMs) can bring e-beam sterilization in-house using steel or concrete shielding for protection. The cost to purchase, operate and maintain an electron accelerator may limit their in-house use to larger OEMs.
Manufacturers can add accelerators to existing factories and sterilize one product at a time on the line, or build protective chambers or dedicated, on-site facilities to sterilize larger boxes and, in some cases, pallets. Electron beam sterilization equipment is generally less expensive than gamma ray or x-ray sterilization, which are not often used in-house by OEMs.
How does e-beam sterilization compare to gamma ray sterilization?
Gamma ray sterilization is a more commonly used form of radiation sterilization than electron beams. Gamma ray sterilization offers deeper penetration than electron beam sterilization, so it may be a better choice for medium-density and high-density devices.
But e-beam sterilization is faster than Gamma ray sterilization, and its irradiation level can be increased, decreased, and turned off when not in use.
Electron beam sterilization does not use radioactive material. Gamma ray sterilization requires Cobalt-60, a radioactive isotope also used for radiation therapy. Colbalt-60’s radioactivity makes it a sabotage target and key ingredient in a hypothetical dirty bomb, a terror risk that spurred the Department of Energy’s National Nuclear Security Administration to encourage non-radioactive alternatives.
Gamma ray sterilizers need Cobalt-60 replenishment annually, and it can take years to obtain for a new facility.
How does e-beam sterilization compare to X-ray sterilization?
E-beam sterilization is more commonly used than X-ray sterilization. X-ray sterilization uses photons and has greater penetration than electron beam sterilization, making it better for dense devices or pallets. But X-ray sterilization isn’t as fast as E-beam sterilization and X-ray equipment is the most expensive of the radiation sterilization methods.
Electron beam sterilization and X-ray sterilization are both non-radioactive, leave no residue and can be turned off when not in use. E-beam sterilization can offer more focused dosing.
