Current issues on EPR dose reconstruction in tooth enamel.

This paper focuses on the opportunities to gain risk assessment information from populations exposed to ionizing radiation. Details are presented on the scale of the nuclear events in several areas within the former Soviet Union. An overview of the issues associated with dose reconstruction by electron paramagnetic resonance (EPR) is given. Principles and outline of the EPR tooth enamel dose assessment are described. Technical details, the latest achievements and the problems of each procedural step are analyzed. In addition, the present accuracy of the EPR dose reconstruction, its problems and cost are discussed

South ural nuclear workers: Comparison of individual doses from retrospective EPR dosimetry and operational personal monitoring.

As a result of EPR investigations on tooth enamel from radiation workers of the Russian nuclear facility 'Mayak' in South Ural, individual doses are reconstructed. The individual doses obtained range up to 3.89 Gy. It is shown that the reconstructed doses are unreasonable until very good agreement with the original personal doses as provided by the radiation protection authority. The findings first prove the applicability of EPR dosimetry on tooth enamel for a life-time including accident dose reconstruction of individuals as a basis for epidemiological studies

Parameters affecting EPR dose reconstruction in teeth.

The aim of this paper is to analyze the lower limit of detection (LLD), linearity of dose response, variation of radiation sensitivity between different tooth enamel samples, and time/temperature stability of EPR biodosimetry in tooth enamel. The theoretical LLD is shown to be 0.46 mGy, which is far lower than the measured value of about 30 mGy. The main issues to lowering LLD are the differentiation of the radiation-induced component against the total EPR spectrum and the complex nature of the dose dependence of the EPR signal. The following questions are also discussed in detail: need for exfoliated or extracted teeth from persons of interest, accounting for background radiation contribution; conversion of tooth enamel absorbed dose to effective dose; accounting for internal exposure specifically from bone-seeking radionuclides. Conclusions on future development of EPR retrospective biodosimetry are made

Assessment of an alanine EPR dosimetry technique with enhanced precision and accuracy.

Dose reconstruction in the course of a series of blind tests demonstrated that an accuracy of 10 mGy for low doses and 1% for high doses can be achieved using EPR spectroscopy. This was accomplished using a combination of methodologies including polynomial filtration of the EPR spectrum, dosimeter rotation during scanning, use of an EPR standard fixed into the resonator and subtraction of all nonradiogenic signals. Doses were reconstructed over the range of 0.01-1000 Gy using this compound spectral EPR analysis. This EPR technique, being equally applicable to fractionated doses (such as those delivered during multiple radiotherapy treatments), was verified to exhibit dose reciprocity. Irradiated alanine dosimeters which were stored exhibited compound spectral EPR signal fading of ca 3 % over 9 months. All error estimates given in this paper are given at the 1 standard deviation level and unless otherwise specified do not account for uncertainties in source calibration