Retrospective dosimetry using fingernail in nuclear industries: A review paper

Generally, doses greater than 2Gy can produce acute biological effects in humans. For this reason, to measure and record the cumulative dose, especially in radiation users, the need for a personal dosimeter has been strongly felt by the researchers. The purpose of this study is to introduce retrospective dosimetric techniques, in particular the use of nails as a natural tool for determining cumulative absorbed dose in the body. The traditional methods of dosimetry are based on the effects of radiation on inorganic materials. Contrary to conventional methods, organic compounds are also used for dosimetry, which the effect of radiation on them is creation of free radical. EPR spectroscopy is used to determine the concentration of these radicals. So far, various solids such as sugars, polymers, quartz and bone have been used for a wide range of absorbed doses (10-108 Gy). In order to develop measurable lower doses (1-5 Gy), materials that are more sensitive to radiation are required. EPR spectroscopy is usually performed in the X-band region at a frequency of 9.5 GHz. The sugar dose-response curve for gamma radiation is linear in the range of 0.5-100 Gy. The dose-response curve for most plastics is nonlinear with low stability of EPR signal. The flax which composed of a polysaccharide chain has a linear dose-response curve in 10-104 Gy, but it is not easy to interpret the EPR signal because of the presence of detergent in it. The intensity of the EPR signal of wool is weak and the recombination of its radical occurs rapidly. Tooth enamel is a good tissue for EPR dosimetry and its dose-response curve is within the range of 0.02-0.2 Gy. The detection limit for the bone is also about a few kGy and not precise at low doses. The background signal in hair is high and its signal stability is low. Also, the EPR signal of fingernail is stable for at least a few days. Generally, materials used in EPR dosimetry should have features such as, being everywhere, non-invasive sampling, signal stability, and accurate and fast dose evaluation. Due to having all of these features compared to other materials, the fingernail is very much considered in the EPR dosimetry method.