Effect of Sample Grain Size on the CO33- Signal Intensity in ESR Dosimetry of Human Tooth Enamel.

Experiments were made to determine the effect of sample grain size on theCO33-signal intensity and the effect of sample orientation in dental ESR dosimetry. Tooth enamel was separated from other parts of teeth, and irradiated with60Cogamma-rays up to about 1290×10-4C/kg (500 R) . The irradiated tooth enamel fragments were crushed, sifted and classified in 9 grain size groups. Three samples of each group were subjected to ESR measurements. For a grain size above 1400μm, directional dependence appeared remarkably. On the other hand, samples of grain size under 300μm showed distorted ESR spectra and gave smaller signal intensity. It is concluded that the sample sizes ranging 500-1400μm are most suitable for dental ESR dosimetry.