Technique for increasing reproducibility in EPR dosimetry of tooth enamel

Variations in several electron paramagnetic resonance (EPR) spectral parameters of importance in retrospective dosimetry of tooth enamel were measured using instrumentation and methodologies designed to maximize measurement reproducibility. Measurements were made using accessory EPR equipment that can be readily constructed with little more than a variable power supply, a geared down motor and some high-purity CaO. Spectroscopic precision is considerably enhanced due to elimination of sample anisotropies by scanning samples throughout their angular range. Frequency drifting incurred by sample reorientation and instrument/sample warm-up is effectively eliminated using an in-cavity :CaO standard. This work shows that for highly anisotropic samples, spectral characteristic parameters (peak-to-peak amplitudes, signal component widths and positions) are reproduced with equal or comparable precision to the case where standard EPR configurations are used while measuring approximately isotropic samples.