The Study Of Improving The Accuracy Of Fingernail-electron Paramagnetic Resonance Dosimetry

Fingernail electron paramagnetic resonance (EPR) is a promising biodosimetric method. Fingernails are sensitive biomaterials to ionizing radiation. Therefore, the kerma can be estimated through measuring the amount of free radicals within fingernails by EPR. However, this dosimetry is deficient and insufficiently accurate yet. Several experiments were designed to find uncertainty of electron paramagnetic resonance dosimetry in fingernails at low-dose level. In the sample processes and measurements, water plays a significant role. This paper has discussed all effects of water on fingernail EPR dosimetry, including the disturbance to EPR measurements and two different effects on the production of free radicals. Crystal water or bound water within fingernails could promote the generation of free radicals induced by radiation, due to the indirect ionizing effect. Therefore, different water content within fingernails could lead to a different growth rate of free radical concentration after irradiation, and these two variables had a linear relation with the slope of 1.8143. So, the current EPR dosimetry needs to be corrected based on water content of different individuals. Free water could block the generation of free radicals induced by radiation. Therefore, soaking fingernail pieces into water before irradiation, just like many researchers previously did, could cause an uncertainty. The samples irradiated at 0,1,2,3,5 Gy were measured after dehydration, to establish the dose-response relationship. The BKG intensity of fingernails from 5 different fingers of one individual were measured. The dose-response relationship was still disordered. The BKG intensity of fingernails from 5 different fingers was quite different. The biggest difference in the experimental group was 55.89%. As described above, the radical concentration of 5 different fingers’nails was different, and cannot be regard as the same like other researchers. The water content in fingernails influenced the accurate EPR measurements, so the procedure of dehydration should be needed before measurements in future investigation.