Influence of crushing and additive irradiation procedures on EPR dosimetry of tooth enamel

The effect of the crushing and additive dose procedures used in EPR dosimetry of enamel was studied on the signals with g-factors of 2. 0045 and g, = 2.0018, g. = 1.9975. Eight fractions, ranging in size from <75 micrometers to 2 mm, were prepared from one tooth. Two cases were investigated: crushing of a non-irradiated sample and of a sample previously irradiated (6 Gy from `Co gamma ray source). In the non-irradiated study, the intensity of the native signal at 2.0045 in by circa 1.75 times as the grain size decreased from maximum to minimum. A small in radiation sensitivity (< 8%) was also observed with decreasing grain size. In the irradiated samples, crushing resulted in slight variations of reconstructed doses from expected values, but the worst possible case (grain sizes < 75 micron) showed that additional errors were less than 10%. The radiation sensitivity of enamel measured immediately after exposure is underestimated. It increases by about 15% in the first month. Based on the decomposition of the observed spectra, a new interpretation of transient signals 1108 is proposed which explains the above phenomena. Recommendations about how to use this interpretation in retrospective EPR dosimetry are given