Radiation sterilization monitoring

The major objective in validating a radiation sterilization process, regardless of whether the mode of radiation is cobalt-60, cesium-137, or electron beam, is to determine the D value of the indicator micro-organism used to monitor the process. With radiation sterilization, the D value is defined as the dose of radiation in Mrads or kilograys necessary to produce a 90% reduction in the number of indicator microbial cells. The D value depends on such factors as temperature, moisture, organism species, oxygen tension, and the chemical environment and/or phys-... 

Used to validate and monitor radiation sterilization processes Vaccine against whooping cough 0.22-pm filter challenge test... 

The effect of y-irradiation on polyanhydrides for sterilization purposes has been studied. Several polymers were y-irradiated with 2.5 Mrad dose and the properties of the polymer before and after radiation were monitored. All polymers did not change in color or pliability as well as the 1H-NMR and IR spectra remain the same. The polymers did not change in molecular weight after irradiation as shown in Table 17. 

Radiation-sensitive color discs, not to be confused with plastic dosimeters, are used to differentiate between packages which have been subjected to irradiation and those which have not They are not indicators of successful sterilization, and the monitoring of radiation sterilization by calibrated plastic dosimeters is the only way of ensuring that the sterilizing dose has been given. 

Some of these systems (hke dyed cellulosic materials and indicator dyes in halogenated materials) are not accurate and reproducible enough for absorbed dose measurement, but these systems can be used as dose monitors or indicators to distinguish between irradiated and nonirradiated materials, e.g., in radiation sterilization (McLaughlin et al. 1988). 

Pharmaceuticals for injection must be presented in a sterile form. Sterility may be achieved by filtration through 0.22 pm filters under aseptic conditions, or by steam, dry heat, radiation or gas sterilisation methods, which may be applied to packaged products. Irrespective of the method, the process must be validated and monitored to assure its effectiveness. As discussed in Chapter 2, this is an example of a process that cannot be assured by verification testing because of its destructive nature. 

Radiation monitors are continually employed to detect any radiation leakage during operation or source storage, and to confirm a return to satisfactory background levels within the sterilization chamber following operation. The dose delivered is dependent upon source strength and exposure period, with dwell times typically up to 20 hours duration. 

In Chapter 5.4, optical ultraviolet radiation sensors are described, including UV-enhanced silicon-based pn diodes, detectors made from other wide band gap materials in crystalline or polycrystalline form, the latter being a new, less costly alternative. Other domestic applications are personal UV exposure dosimetry, surveillance of sun beds, flame scanning in gas and oil burners, fire alarm monitors and water sterilization equipment surveillance. 

During the sterilization procedure the radiation dose should be monitored. For this purpose established dosimetry procedures should be used, giving a quantitative measurement of the dose received by the product itself. Biological indicators should only be used as additional control. The information obtained should form part of the batch record. 

During the sterilization procedure the radiation dose should be monitored. For this purpose established dosimetry procedures should be used, giving a quanitative measurement... 

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