ESR and TL dosimetry systems: comparative measurements for human phantom

Tooth enamel EPR dosimetry: sources of errors and their correction

Some of the most important sources of systematic errors in dose determination using tooth enamel EPR spectroscopy and ways of reducing those errors are discussed. Enamel from the outside of the front teeth should not be used for dose determination because of induction of paramagnetic centers by solar light. The accuracy of the method in the low dose range is limited by variation in the shape of the EPR signal of unirradiated enamel, which can be described by an initial intrinsic signal and which varies for different samples with standard deviation of 20-30 mGy. The energy dependence of enamel sensitivity should be taken into account in the form of a correction factor. The value of this factor is estimated at 1.1-1.3 for real radiation fields in radiation contaminated territories. Variation in enamel sensitivity for different samples is shown to be within limits of 10-15% of the average value.

Application of EPR retrospective dosimetry for large-scale accidental situation

Above 3000 tooth enamel samples, collected at population of radioactive contaminated territories after Chernobyl accident, the Chernobyl liquidators, the retired military of high radiation risk and the population of control radiation free territories were investigated by EPR spectroscopy method in order to obtain accumulated individual exposure doses. Results of EPR spectra measurements are stored in data bank; enamel samples are also stored in order to provide the possibility to repeat the measurements in future. Statistical analysis of results has allowed to detect the contribution into EPR signal in tooth enamel due to the action of the natural background radiation, and the radioactive contamination of territory. In general, the average doses of external exposure of the population obtained with EPR spectroscopy of teeth enamel are consistent with results based on other methods of direct and retrospective dosimetry. Essential exceeding of the individual doses above the average level within the population groups was observed for some persons. That gave the possibility to detect the individuals with overexposure, which were included into groups for medical monitoring.