Dosimetric properties of commercial grade plexiglas as a possible routine dosimeter for radiation processing

Dyed and undyed polymethylmethacrylate (PMMA) are commercially available for high dose dosimetry in radiation processing applications. In order to investigate the properties of the locally available clear perspex as a subsitute routine dosimeter, we have looked into the optical and dosimetric properties of clear perspex sheets with a thickness of 2 mm.

The selected wavelength used for read out was 314 nm. Absorption spectra obtained showed a sharp cutoff at 260 nm wavelength. Post-irradiation studies at different doses indicate that the optical density decrease with storage time. No significant dose rate dependence in the range of 1.1 to 11 kGy/hr has been observed. The temperature response of the said clear perspex in the range of 0–30°C during irradiation has also been determined.

Comparison of the optical density versus dose for the local clear perspex against that of red perspex from Harwell, at an absorbed dose of 25 kGy, as obtained in our gamma irradiator, IR-136, showed a difference of 3%. The reproducibility of the local clear PMMA has been observed to be also less than 3% in an absorbed dose range of 5 to 50 kGy.