Differentiation of the observed low frequency (1200MHz) EPR signals in whole human teeth.

We have determined the properties of the various signals that are observed in vivo so this information can be used to develop procedures for data acquisition and data analysis that will enable the accurate determination of radiation-induced dose with a resolution of 50cGy. Using the 1200MHz in vivo EPR spectrometer and isolated human teeth, we found four types of signals whose properties overlap, but also have some distinct properties that can be exploited to resolve them. The intrinsic background signal in human teeth differs modestly from the radiation-induced signal in g-factor, shape, and power saturation. Random noise from instrumental conditions can be reduced with signal averaging. The microphonic signal varies with the particular experimental setup and has some properties similar to real EPR signals, but is constant if the conditions are not changed. It can be suppressed by improvements in hardware and software, or subtracted.