Polymethylmethacrylate dosimeters

Polymethylmethacrylate dosimeter. Several types of polymethylmethacrylate are known as potential dosimeters, and one system, clear (HX) Perspex, was developed for routine dose measurement (ISO/ASTM 51276). It is prepared using benzod peroxide as polymerization initiator. The irradiated clear Perspex dosimeters are measured hy spectrophotometry usually at 314 nm or 315 nm, as the most stable wavelengths for evaluation (Chadwick 1969). The response of the HX Perspex was found to be independent of irradiation temperature in the range of 0-30° C, but at higher temperatures the response was decreasing (Miller and McLaughlin 1981). Miller et al. (1975) observed the effect of dose rate on the response too at values above 10 Gy s . ... 

Dyed polymethylmethacrylate (PMMA) dosimeter. Polymethylmethacrylate dosimeters containing different types of dyes have been developed for routine dosimetry mainly in radiation sterilization and have been used extensively for many decades (Whitakker 1970 ISO/ASTM 2002e). Various types of the PMMA dosimeters are known, but the most popular are the red Perspex, the amber Perspex, and the Gammachrome YR. 

The quality control checks whether the product has been irradiated homogeneously and received the correct dose. The controllable variables are the source intensity and the exposure time. The process control is performed with a dosimeter, for example plates of polymethylmethacrylate (PMMA) that discolours under the influence of gamma radiation. The extent of discolouration is dependent on the absorbed dose. In one container several dosimeters are placed, which are analysed in the quality control laboratory afterwards in a spectrophotometer. 

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See also in sourсe #XX -- [ ]

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