Investigation of the dose-response in multiple irradiated fingernails and the combined effect of drying time-temperature to the ESR signal

Abstract Free radicals are formed when human fingernails are exposed to ionizing radiation. These free radicals can easily be detected using an electron spin resonance (ESR) technique. Although recent works have made important contributions to the development of ESR technique with fingernails, the effects of multiple irradiations on sensitivity of the radiation-induced signal and the influence of heat in the drying process of the samples have not been explored adequately. The researchers of this study have investigated the potential effects of multiple irradiations and exposure to heat on the ESR signals of fingernails. As a result, the slope of the dose-response curves decreased which reflected in the decrease of the sensitivity after multiple irradiations of the same fingernails to doses 35 Gy or 70 Gy of 137Cs γ-rays. Furthermore, it was observed that heat exposure considerably affected the visual shape and peak-to-peak intensity of the ESR spectra. Heating to temperatures above 80 °C resulted in a noticeable increase to the intensity of the ESR spectra – generating a new ESR signal that overlapped with the native background signal in unirradiated fingernail samples. The results of this study suggested that some potential confounding effects need to be accounted carefully if ESR dosimetry of fingernails is to be applied in real radiation accident situations.