Radiation sterilization doses

Ethylene oxide treatment can also be considered as an alternative to radiation sterilization in the commercial production of disposable medical devices (Chapter 19). These techniques do not, however, offer the same degree of sterility assurance as heat methods and are generally reserved for temperature-sensitive items. 

As mentioned in Chapter 3, DI water has now replaced distilled water for most laboratory purposes. PVC pipe, which is both inexpensive and easy to install, is normally employed to carry the water to points of usage. It is very important that the lines do not have dead legs where water is allowed to stand, since this could encourage bacterial growth. In cases where sterile water is needed, special steps must be taken. The water may be boiled, which also drives out dissolved gases, or ultraviolet radiation may be employed, a common method in the cosmetics industry. Membrane filters will also effectively remove bacteria. Laboratories needing sterile water often use two bacteria removal systems of... 

Most medical devices require sterilization before packaging and use. The most common methods for doing this include -irradiation, exposure to ethylene oxide (EtO) gas or electron beam (E-beam). Contact with radiation, ethylene oxide or electron beam can affect not only the microorganisms of concern, but also potentially the medical device or package. The physical properties were tested after irradiation to define any deleterious effect... 

Sterilization processes do not result in a product that can be described as absolutely sterile or non-sterile inasmuch as the process is a statistical phenomenon. A variety of techniques are availablej including heat, radiation, ethylene oxide sterilization, and sterile filtration. 

Unlike stochastic effects, non-stochastic effects are characterized by a threshold dose below which they do not occur. In addition, the magnitude of the effect is directly proportional to the size of the dose. Furthermore, for non-stochastic effects, there is a clear causal relationship between radiation exposure and the effect. Examples of non-stochastic effects include sterility, erythema (skin reddening), ulceration, and cataract formation. Each of these effects differs from the other in both its threshold dose and in the time over which this dose must be received to cause the effect (i.e. acute vs. chronic exposure). 

Identity and purity, stability, and sterility and apyrogenicity. The identity and purity of radiopharmaceuticals is verified by determining the radionuclidic and radiochemical purity. Stability concerns the radioactive label, which is related to radiochemical purity at a certain time after preparation. Since Tc pharmaceuticals are formulated as sterile, pyrogen-free solutions, the safety requirements of drugs for parenteral use do apply. Safe handling of the radionuclide is equally important and must comply with Euratom Directives, regulated by national law for radiation protection, which also concerns the application of radionuclides in adults and in children for diagnostic procedures. 

Real-World Reading Link Almost everyone gets cuts or scrapes from time to time. Usually, the first thing you do is clean the injury and cover it with a bandage to keep out germs. One of the many uses of radiation is to sterilize medical bandages. 

Polymers used in nontoxic sterilizable items, such as tubing, artificial organs, and wound coverings, must be able to withstand sterilization by ethylene oxide, steam autoclave, or gamma radiation. For medical products sterilized by gamma irradiation, only plastics that do not degrade or discolor on exposure to radiation, such as polyester and polycarbonates, can be used. 

Sterilization is an important process that involves a major market for the use of plastics in packaging. The most common methods of sterilization are those using heat, steam (autoclaving), radiation, and gas (EtO—ethylene oxide) (see Tables 4-5 and 4-6). Unfortunately, each of these methods has its limitations. There are, however, plastics that do meet performance requirements based on the various different processes, including radiation. 

Radioactivity is also used to control the populations of harmful insects. For example, fruit flies can be raised in large numbers in captivity and sterilized with radiation. When these fruit flies are released, they mate with wild fruit flies but do not produce offspring. 

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