what is radiation sterilization
Radiation sterilization is an effective method to kill microorganisms on most substances by ionizing radiation. The electromagnetic waves used for sterilization include microwave, ultraviolet (UV), X-ray and gamma ray.
The three radiation forms of radiation sterilization include gamma radiation, electron beam (electron beam) radiation and X-ray radiation.
two types of irradiation sterilization devices equipment
One is to use Co-60 gamma source, the other is to use accelerator. In terms of the radiation power, a 14kw accelerator is equivalent to a 1 million Curie cobalt-60 radiation source; however, since the cobalt-60 source emits radiation in a spherical shape, the utilization rate of the radiation is low, only about 20%, and the rays in other directions are wasted. However, the ray direction of the accelerator is one direction, and the utilization rate of the radiation is high, up to 93%. So if we take into account the utilization rate of the electron source of 4.7-4.7 million.
Irradiation sterilization technology
During the sterilization process, the target sample is bombarded by high-energy electrons or high-energy electromagnetic radiation, which leads to the formation of extremely unstable free radicals, molecular ions and secondary electrons. These radiation products then react with nearby molecules, breaking and changing chemical bonds. In particular, DNA is highly sensitive to the damaging effects of radiation, and will break, depolymerize, mutate and change its structure after exposure to ionizing radiation. Incomplete repair of DNA damage will eventually lead to loss of genetic information and cell death. Therefore, radiation can kill harmful microorganisms and is used as a sterilization technique.
How long is the radiation sterilization cycle?
The radiation time of general products is 2 to 8 hours, while that of medical products is more than 30 hours. When you come out, the bacteria on your body will be completely eliminated by the radiation of nuclear radiation.
The length of sterilization time is related to the power of sterilization device. The higher the power, the greater the dose provided in unit time, the shorter the irradiation time. It is also related to the initial bacteria content of the irradiated object. The higher the initial bacterial content, the greater the dose required and the longer the time required. Generally speaking, with the electron accelerator sterilization, a day can be about 30 tons of Chinese medicine sterilization.
Radiation sterilization uses ionizing radiation to sterilize medical devices. In recent decades, with the construction of more and more facilities, the development of radiation-resistant materials and the stricter definition of dose levels, its use has also increased. The introduction of electron beam sterilization also expands the application range of radiation sterilization.
Gamma rays from a cobalt-60 (60Co) isotope source or machine-generated accelerating electrons are used. Gamma radiation is the most common form of radiation sterilization. When materials are sensitive to high temperature of high pressure sterilization but compatible with ionizing radiation, gamma radiation is used. Exposure is achieved when the package is transported around the exposed 60Co source for a specified period of time. The most commonly used effective dose for sterilization of medical devices is 25kgy.
The germicidal efficacy of gamma rays depends on the oxidation of biological tissues. It is a simple, rapid and effective sterilization method. However, the high cost of capital is a major disadvantage. Most metal medical devices can be sterilized by radiation. However, it is well known that sterilization of biomedical polymers with gamma rays can lead to physical changes, including embrittlement, discoloration, odor generation, hardening, softening, increase or decrease in melt temperature, and decrease in molecular weight.
These changes involve two mechanisms: chain breaking and crosslinking, and mechanical properties such as tensile strength, elastic modulus, impact strength, shear strength and elongation may be affected. It is reported that the fatigue strength of some biomedical polymers decreases after gamma radiation. Embrittlement may occur and the crystallinity may change. It has also been reported that gamma radiation can amplify the surface defects of some biomedical polymers, and Fourier transform infrared (FTIR) studies have shown that some biomedical polymers have obvious oxidation.
Gamma irradiation also has adverse consequences because it may produce toxic degradation products, such as' - methylene diphenylamine (MDA), which can be produced when high molecular weight polyurethane materials are decomposed by irradiation. Cytotoxic effects were also reported after exposure to gamma irradiated polyurethane samples, which are believed to be caused by the effects of low molecular weight by-products.
Three principles of radiation sterilization protection
(1) Time protection: Regardless of the exposure, the cumulative dose of human exposure is proportional to the exposure time. The longer the exposure to radiation, the more serious the radiation hazard. Minimize the time spent on radioactive work to achieve the purpose of reducing the exposure dose.
(2) Distance protection: The radiation dose rate of a place is inversely proportional to the square of the distance from the radioactive source. The greater the distance from the radioactive source, the smaller the dose rate there. So stay away from radioactive sources as much as possible during work. To achieve the purpose of protection.
(3) Shielding protection: is to set up a protective barrier between the person and the radioactive source. Because the rays pass through substances with high atomic numbers, they will be absorbed a lot, so the radiation dose reaching the human body is reduced. Commonly used shielding materials include lead, reinforced concrete, lead glass, etc.
irradiation sterilization advantages and disadvantages
irradiation sterilization advantages
Compared with traditional chemical sterilization or heat sterilization, radiation sterilization has many advantages:
Terminal processing: Due to the penetration depth of ionizing radiation, the product can be processed in its completely sealed final packaging. This limits the risk of contamination after sterilization.
Cold method/temperature independence: The temperature rise during treatment is minimal. In addition, radiation sterilization has no heat dependence and is effective at both ambient temperature and sub-zero temperature. It is compatible with temperature-sensitive materials such as pharmaceuticals and biological samples.
Chemical independence: No volatile or toxic chemicals are required. In the case of X-ray or electron beam irradiation, the final product that needs to be processed will not be produced during the procedure.
No residue: Radiation will not leave residue on the sterilized product.
Flexibility: Radiation can sterilize products of any phase (gas, liquid or solid materials), density, size or thickness, and products of homogeneous or heterogeneous systems. In addition, sterilization can be performed at any temperature and pressure.
Time efficiency: electron beam sterilization can be completed in a few seconds to a few minutes.
Sterility Assurance Level (SAL): Radiation treatment can produce SAL of 10-6 or higher, ensuring that less than one millionth of the microorganisms survive the sterilization process.
Ease of use: Only one variable, exposure dose/time, must be monitored, making radiation sterilization simple and easy to control.
irradiation sterilization disadvantages
However, radiation sterilization technology does have many disadvantages:
Instruments: High capital costs and usually require specialized facilities. Gamma radiation requires a nuclear reactor; electron beam/X-ray radiation is produced using an electron beam accelerator.
Product degradation: Radiation-based methods are not suitable for all materials and may cause damage to packaging materials and/or products. Ordinary plastics such as polyvinyl chloride (PVC), acetal and polytetrafluoroethylene (PTFE) are sensitive to gamma rays. The high energy involved in electron beam radiation can also cause main chain scission (long chain main chain scission) and chemical cross-linking of packaging polymers.
Radioactive materials: When gamma rays are used as an ionization source, radiation sterilization requires handling and disposal of radioactive materials. Note that under the usual radiation levels, gamma ray irradiation will not produce radioactivity in the processed sample.
Types of radiation sterilization
Radiation is divided into two types: ionizing radiation and non-ionizing radiation.
Ionizing radiation is characterized by short wavelength, high frequency and high energy.Ionizing radiation includes cosmic rays, X-rays, and radiation from radioactive materials.
Non-ionizing radiation includes ultraviolet, thermal radiation, radio waves and microwaves.
There are generally two types of radiation used for disinfection, ionizing radiation and non-ionizing radiation. Ionizing radiation is the use of short-wavelength, high-intensity radiation to destroy microorganisms. This radiation may appear in the form of gamma rays or X-rays, which react with DNA and cause cell damage. Non-ionizing radiation uses longer wavelengths and lower energy. Therefore, non-ionizing radiation loses its ability to penetrate materials and can only be used for surface disinfection. The most common form of non-ionizing radiation is ultraviolet light, which is used in various ways throughout the industry.
radiation sterilization company
The company has more than ten years of experience in the field of radiation sterilization. The overall operation quality standard has passed the audit of TUV certification company in Germany, and obtained the latest version of iso111337, ISO13485 and ISO9001 With the management system certificate, stable quality system and precise sterilization dose setting, we can meet the sterilization requirements of all aspects of your products. We can develop special sterilization process according to different products and provide a series of professional customer service. The company's overall sterilization field involves disposable medical supplies, packaging materials, food, cosmetics, all kinds of implanted tissue equipment, all kinds of implanted medical equipment, pharmaceutical products and related packaging materials, related biomedical medical equipment, all kinds of raw materials of products, etc.