EPR studies performed in TAEA- SANAEM and two more approaches on nail dosimetry : An EPR study
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Date
2015-12
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International Association of Biological
EPR Radiation Dosimetry (IABERD)
EPR Radiation Dosimetry (IABERD)
Abstract
The missions of Turkish Atomic Enery Authority and its center called Sarayköy Nuclear Research and Training center (SANAEM) and the accreditation scope of SANAEM (Table 1) will be presented. Electron Paramagnetic Resonance (EPR) studies of Dosimetry laboratory in Technology Department cover Retrospective Dosimetry, Detection of Irradiated Foods, Biodosimetry and Dating. To fulfill the accreditation requirements of TS EN ISO/IEC 17025 standard, this laboratory have performed intercomparion studies on dosimetry and detection of irradiated foodstuffs. In this presentation, EPR studies on fingernail dosimetry as biodosimetry for emergency will also be discussed in detail. These studies have been performed for a long time in means of rapid and accurate retrospective dosimetry. The most important outcome of these studies is the identification of a stable radiation induced signal (RIS5) component in nails by IRSN, France. Here, we present the result of two approaches on nail dosimetry; one based on the described protocol by Trompier et al. 2014 and the other used classical added dose method.
The nail samples were collected from same donor cutting after 3 weeks, divided into two groups; one was for non-exposed and the other was exposed to an accident dose as 15 Gy checked by alanin dosimeter, cut into small parts, humidified in distilled water about 10 min. and dried on the towel in air about 1 day (in the dark). To control humidity, the samples were weighted (~ 24 mg) before and after each measurement. In the first protocol; when adding new dose, the process of humidification and drying were repeated before each set of measurements. In the second one; these process were performed only before the first measurement to avoid mechanical induced signals (MIS). The samples were irradiated with 137Cs gamma rays (0.5 kGy/h). EPR measurements were carried out using a Bruker e-scan X-band EPR spectrometer. A microwave power of 1 mW was adjusted during the experiment according to MW studies of background, MIS and RIS signals (not presented). The samples irradiated up to dose of 30 Gy and 168 Gy was used to construct the added dose-response curves in steps of 5 and 10 Gy. The reported intensities of RIS5 and center field signal (near g=2.004) were derived from peak-to-peak distance of the ESR signal. In the first protocol, the dose saturation for the non-exposed sample was reached after having added dose 15 Gy, whereas for exposed, the signal intensity decreased already for the first post-irradiation (Figure 1). It seems that the nails have used have a dose saturation point about 15 Gy. That’s why the signal of sample given accident dose was decreased when adding dose, because of the initial dose of 15 Gy, after it reaches a level for which even with added new dose, the intensity did not change any more. On the other hand, in the second protocol, the ESR signal intensity increases with increasing added dose. The experimentally measured ESR signal intensity values (y) were fitted well by polynomial function (y=aD2+bD+c; -0.003±0.0004, 1.15± 0.07 and 29.29±2.54 ,r2=0.9922). The extrapolated dose was calculated to be 15.84 Gy (Figure 2).
Consequently, a new approach in nail dosimetry using the RIS5 component and classical approach using center field RIS signal have been found to be successful methods for the evaluation of dose to fingernails exposed high-doses . Further studies should be planned to test them for lower accident dose on more samples from different individual.
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Keywords
TAEA SANAEM, TAEK SANAEM, Nails, Çiviler, Biodosimetry, Biyodosimetri, Added dose response, Eklemeli doz cevap, EPR
Citation
Tepe Çam, S. (2015) EPR studies performed in TAEA-SANAEM and two more approaches on nail dosimetry : An EPR study. EPR BioDose 2015, 4-8 October 2015. Hanover, New Hampshire USA.