Preliminary analysis of the integrated EPR signals of fingernails to validate the dosimetry method based on peak-to-peak amplitudes.

Abstract

Introduction: Although the dosimetry technique using fingernails coupled with electron paramagnetic/spin resonance (EPR/ESR) spectroscopy (hereafter called 'fingernail EPR dosimetry') has practical advantages, more efforts to improve its accuracy and reliability are required for application to dose assessment in radiological accidents.

Purpose: In fingernail EPR dosimetry, an absorbed dose is determined from the peak-to-peak amplitude of the main peak of the EPR signal spectrum, whereas the measured spectrum is the first derivative of the microwave absorption band. This study aimed to confirm the validity of this approach based on peak deconvolution analysis of the integrated EPR spectra of irradiated fingernails.

Methods: Fingernail samples collected from two donors (an 11-year-old child and a 62-year-old adult) were irradiated with X-rays (160 kV, 6.3 mA) at different doses (0, 5, 10, and 20 Gy) and EPR signals were measured using an X-band EPR spectrometer. The measured EPR spectra were integrated and deconvoluted into major components.

Results: The integrated EPR spectra were successfully deconvoluted into three Gaussian peaks with central magnetic field values of 327.42, 327.55, and 327.63 mT. All the peaks of the child fingernails showed linear dose responses. In contrast, the three peaks of the adult fingernails presented notably different dose responses; it was implied that the reduction in radiation sensitivity of the peak-to-peak amplitude was not attributable to the major peak.

Conclusions: The findings presented in this study underscore the importance of examining the behaviors of the overlapping peaks in fingernail EPR spectra on an individual basis to achieve more reliable fingernail EPR dosimetry.