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
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- "We showed the limitations of EPR on hair as a method for an accident dosimetry, but we provided more systematic information on radiation-induced radicals in hair than has previously been available. A protocol for hair sample can also be written including the sample collection, storage conditions and EPR measurements in emergency situations as an accident dosimetry as done for fingernail samples (Trompier et al., 2007; Wilcox et al., 2010; Alexander et al., 2007). To prepare a biological dosimetry protocol, a number of studies need to be performed on the same kind of samples; thus the generalized findings could be obtained for each individual. "
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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- "In vitro measurements of fingernail clippings in the X-band (Trompier et al. 2007, 2009; Romanyukha et al. 2007, 2010; Reyes et al. 2008, 2009, 2012; Black and Swarts 2010; Wilcox et al. 2010); In vitro measurements of fingernail clippings in the Q-band (Romanyukha et al. 2011; Trompier et al. 2014a); In vivo measurements of fingernails in the X-band (He et al. 2011). "
ABSTRACT: In this paper, we report results of radiation dose measurements in fingernails of a worker who sustained a radiation injury to his right thumb while using 130 kVp X-ray for nondestructive testing. Clinically estimated absorbed dose was about 20-25 Gy. Electron paramagnetic resonance (EPR) dose assessment was independently carried out by two laboratories, the Naval Dosimetry Center (NDC) and French Institut de Radioprotection et de Sûreté Nucléaire (IRSN). The laboratories used different equipments and protocols to estimate doses in the same fingernail samples. NDC used an X-band transportable EPR spectrometer, e-scan produced by Bruker BioSpin, and a universal dose calibration curve. In contrast, IRSN used a more sensitive Q-band stationary spectrometer (EMXplus) with a new approach for the dose assessment (dose saturation method), derived by additional dose irradiation to known doses. The protocol used by NDC is significantly faster than that used by IRSN, nondestructive, and could be done in field conditions, but it is probably less accurate and requires more sample for the measurements. The IRSN protocol, on the other hand, potentially is more accurate and requires very small amount of sample but requires more time and labor. In both EPR laboratories, the intense radiation-induced signal was measured in the accidentally irradiated fingernails and the resulting dose assessments were different. The dose on the fingernails from the right thumb was estimated as 14 ± 3 Gy at NDC and as 19 ± 6 Gy at IRSN. Both EPR dose assessments are given in terms of tissue kerma. This paper discusses the experience gained by using EPR for dose assessment in fingernails with a stationary spectrometer versus a portable one, the reasons for the observed discrepancies in dose, and potential advantages and disadvantages of each approach for EPR measurements in fingernails.Biophysik 06/2014; 53(4). DOI:10.1007/s00411-014-0553-6 · 1.58 Impact Factor
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- "Nails are easy to collect and can possibly give an estimation of the dose distribution when nails from each finger or toe can be analyzed separately. More recently, large efforts have been made to understand the free radicals mechanism in nails and establish EPR nail dosimetry with different approaches (Romanyukha et al. 2007a, 2010; Reyes et al. 2008, 2009, 2012; Trompier et al. 2007b, 2009; Black and Swarts 2010; Wilcox et al. 2010; He et al. 2011). In spite of these efforts, until now, no practical application has been reported, to the best of the authors’ knowledge, mainly because several difficulties have been identified in the development of EPR dosimetry on nails. "
ABSTRACT: Until very recently, analysis of bone biopsies by means of the method of electron paramagnetic resonance (EPR) collected after surgery or amputation has been considered as the sole reliable method for radiation dose assessment in hands and feet. EPR measurements in finger- and toenail have been considered for accident dosimetry for a long time. Human nails are very attractive biophysical materials because they are easy to collect and pertinent to whole body irradiation. Information on the existence of a radiation-induced signal in human nails has been reported almost 25 years ago. However, no practical application of EPR dosimetry on nails is known to date because, from an EPR perspective, nails represent a very complex material. In addition to the radiation-induced signal (RIS), parasitic and intense signals are induced by the mechanical stress caused when collecting nail samples (mechanically induced signals-MIS). Moreover, it has been demonstrated that the RIS stability is strongly influenced not only by temperature but also by humidity. Most studies of human nails were carried out using conventional X-band microwave band (9 GHz). Higher frequency Q-band (37 GHz) provides higher spectral resolution which allows obtaining more detailed information on the nature of different radicals in human nails. Here, we present for the first time a complete description of the different EPR signals identified in nails including parasitic, intrinsic and RIS. EPR in both X- and Q-bands was used. Four different MIS signals and five different signals specific to irradiation with ionizing radiation have been identified. The most important outcome of this work is the identification of a stable RIS component. In contrast with other identified (unstable) RIS components, this component is thermally and time stable and not affected by the physical contact of fingernails with water. A detailed description of this signal is provided here. The discovery of stable radiation-induced radical(s) associated with the RIS component mentioned opens a way for broad application of EPR dosimetry in human nails. Consequently, several recent dosimetry assessments of real accident cases have been performed based on the described measurements and analyses of this component.Biophysik 01/2014; 53(2). DOI:10.1007/s00411-014-0512-2 · 1.58 Impact Factor