Dosimetry based on EPR spectral analysis of fingernail clippings.
ABSTRACT Exposure of fingernails and toenails to ionizing radiation creates radicals that are stable over a relatively long period (days to weeks) and characterized by an isotropic EPR signal at g = 2.003 (so-called radiation-induced signal, RIS). This signal in readily obtained fingernail parings has the potential to be used in screening a population for exposure to radiation and determining individual dose to guide medical treatment. However, the mechanical harvesting of fingernail parings also creates radicals, and their EPR signals (so-called mechanically-induced signals, MIS) overlap the g approximately 2.0 region, interfering with efforts to quantify the RIS and, therefore, the radiation dose. Careful analysis of the time evolution and power-dependence of the EPR spectra of freshly cut fingernail parings has now resolved the MIS into three major components, including one that is described for the first time. It dominates the MIS soon after cutting, but decays within the first hour and consists of a unique doublet that can be resolved from the RIS. The MIS obtained within the first few minutes after cutting is consistent among fingernail samples and provides an opportunity to achieve the two important dosimetry objectives. First, perturbation of the initial MIS by the presence of RIS in fingernails that have received a threshold dose of radiation leads to spectral signatures that can be used for rapid screening. Second, decomposition of the EPR spectra from irradiated fingernails into MIS and RIS components can be used to isolate and thus quantify the RIS for determining individual exposure dose.
SourceAvailable from: Semra Tepe Çam[Show abstract] [Hide abstract]
ABSTRACT: The potential use of human hair samples as biologic dosimeter was investigated by electron spin resonance (ESR) spectroscopy. The hair samples were obtained from female volunteers and classified according to the color, age and whether they are natural or dyed. Natural black, brown, red, blonde and dyed black hair samples were irradiated at low doses (5–50 Gy) and high doses (75–750 Gy) by gamma source giving the dose rate of 0.25 Gy/s in The Sarayköy Establishment of Turkish Atomic Energy Authority. While the peak heights and g-values (2.0021–2.0023) determined from recorded spectra of hair were color dependent, the peak-to-peak line widths were varied according to natural or dyed hair (ΔHpp: 0.522–0.744 mT). In all samples, the linear dose–response curves at low doses saturated after 300 Gy. In black hair samples taken from different individuals, differences in the structure of the spectrum and signal intensities were not observed. The EPR signal intensities of samples stored at room temperature for 22 days fell to their half-values in 44 h in black hair, 41 h in blonde and brown hairs, 35 h in dyed black hair and in 17 h in red hair. The activation energies of samples annealed at high temperatures for different periods of time were correlated well with those obtained in the literature. In conclusion, hair samples can be used as a biological dosimeter considering the limitations showed in this study.Applied Radiation and Isotopes 09/2014; 94:272-281. DOI:10.1016/j.apradiso.2014.08.021 · 1.06 Impact Factor
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ABSTRACT: Soon after the 9-11 attacks, politicians and scientists began to question our ability to cope with a large-scale radiological terrorism incident. The outline of what was needed was fairly obvious: the ability to prevent such an attack, methods to cope with the medical consequences, the ability to clean up afterward, and the tools to figure out who perpetrated the attack and bring them to justice. The medical response needed three components: the technology to determine rapidly the radiation doses received by a large number of people, methods for alleviating acute hematological radiation injuries, and therapies for mitigation and treatment of chronic radiation injuries. Research done to date has shown that a realistic medical response plan is scientifically possible, but the regulatory and financial barriers to achieving this may currently be insurmountable.Health Physics 08/2014; 107(2):164-171. DOI:10.1097/HP.0000000000000082 · 0.77 Impact Factor
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ABSTRACT: Fast and precise retrospective dosimetry is crucial in making decisions about medical procedures and safety measures in radiation accidents. Electron paramagnetic resonance (EPR) spectroscopy has a potential as one of available biodosimetry methods for use in victims of such incidents. In this study, authors present the findings on EPR dosimetry in fingernails. Authors describe changes of EPR signals in unirradiated and irradiated nails in time after cutting and the effect of water on the mechanically induced and radiation-induced EPR signals measured ex vivo in the fingernails. The effect of dose on amplitude of the EPR signal was measured in nails that were soaked for 10 min in water after their irradiation. The obtained dose-response curves, which reflect changes in concentration of the radiation-induced RIS5 radicals, reach their maximum for doses of 40-60 Gy.Radiation Protection Dosimetry 07/2014; DOI:10.1093/rpd/ncu207 · 0.86 Impact Factor