Optimisation of recording conditions for the electron paramagnetic resonance signal used in dental enamel dosimetry.

Optimisation of the parameters for recording the electron paramagnetic resonance (EPR) spectra of dental enamel for absorbed dose reconstruction was performed for an EMX (Bruker) spectrometer supplied with a high-sensitivity microwave cavity. Dose determination was performed using a previously developed automatic spectra processing procedure, which uses the non-linear fit of a model spectrum. The experimental error was estimated as the standard deviation of the results from the nominal doses for the set of spectra recorded for 10 samples prepared from teeth of different persons and irradiated in the dose range 0-500 mGy. The microwave power and magnetic field modulation amplitude corresponding to the minimum of dependencies of the error on these parameters were adopted as the optimal ones. For the sets of spectra recorded at optimal parameters for sample masses 100, 50 and 30 mg, the errors of dose determination were obtained as 18, 27 and 37 mGy respectively.