Radiation dose determination by using nails with ESR biodosimetry technique
Loading...
Date
2020
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Turkish Energy, Nuclear and Mineral Research Agency
Abstract
Son yıllarda, hızlı ve doğru biyodozimetri tekniği olarak tırnaklar üzerinde yapılan Elektron Spin Rezonans (ESR) çalışmalarının sayısı artmıştır. Bu çalışmaların en önemli sonucu, Fransız Radyasyondan Korunma ve Nükleer Güvenlik Enstitüsü (IRSN) tarafından tırnaklarda oluşan kararlı radyasyona bağlı ESR sinyalinin (RIS5) tanımlanmasıdır. Bir diğer önemli sonuç, Dartmouth ESR Merkezi aracılığıyla Amerikan Ulusal Sağlık Enstitüsü (NIH) tarafından desteklenen Sholom ve McKeever tarafından 2016’da yayımlanan çalışmada verilen doz belirleme protokolüdür. Bu çalışmada, tırnak dozimetrisi konusunda önerilen üç yaklaşımın sonuçları sunulmuştur: ikisi yukarıda anlatılan IRSN ve Dartmouth protokollerine dayanmaktadır, diğerinde ise klasik eklemeli doz yöntemi kullanılmıştır. Toplanan tırnak numuneleri Cs-137 gama kaynağında (0.5 kGy / saat) ışınlanmıştır. ESR ölçümleri, Bruker e-scan X-band EPR spektrometresi kullanılarak gerçekleştirilmiştir. 5 ve 10 Gy'lik adımlarla eklemeli doz-cevap eğrilerini oluşturmak için 25, 30, 85 ve 168 Gy dozlarına kadar ışınlanan örnekler kullanılmıştır. RIS5 ve merkez alan (yaklaşık g = 2.004) ESR sinyal şiddetleri, EPR sinyalinin tepeden-tepeye yüksekliği ölçülerek belirlenmiştir (Şekil 1 ve 4). 2016 yılında yayınlanan son protokolü test etmek için ise, tırnak örnekleri Co-60 gama kaynağında 2 ve 5 Gy kaza dozlarında ışınlanmıştır. ESR sinyal şiddetleri, bu protokolde verilen formülde kullanılmak üzere kaydedilmiştir. İlk protokolde, ışınlanmış ve ışınlanmamış örneklerin doyum noktaları arasındaki fark, birinci grup için 15 Gy ve ikinci grup için 10 Gy olarak bulunmuştur (Şekil 2 ve 3). Diğer yandan, ikinci protokolde ESR sinyal yoğunluğu eklenen doza bağlı olarak artmıştır. Deneysel olarak ölçülen ESR sinyal şiddeti değerleri en iyi polinom fonksiyonuna fit edilmiş ve dozlar, 10 ile 15 Gy kaza dozları için, sırasıyla, 13.89 ve 22.19 Gy olarak hesaplanmıştır (Şekil 5 ve 6). Son olarak, Dartmouth Merkezi protokolüne göre, 2 ve 5 Gy kaza dozlarında ışınlanmış örnekler için sırasıyla dozlar 2.18 ve 4.5 Gy olarak hesaplanmıştır. Özetle, RIS5 ESR sinyal şiddeti değişimini kullanan IRSN ve Dartmouth protokollerinin yüksek dozlara maruz kalmış tırnak örneklerinde kaza dozunun değerlendirilmesinde başarılı yöntemler olduğu görülmüşken, merkez alan ESR sinyal şiddeti değişimini kullanan klasik yaklaşımın yüzde 38.9 ve yüzde 47.9 hata ile kaza dozları vermesi sebebiyle bu yöntemin başarılı olmadığı tespit edilmiştir. IRSN ve Dartmouth yaklaşımlarının farklı bireylerden daha fazla örnek üzerinde daha düşük kaza dozları kullanılarak test edilmesi ve bu testlerin de kısa süre içerisinde yanıt verebilmesi yönünde ileri çalışmalar planlanmalıdır.
In recent years, the number of Electron Spin Resonance (ESR) studies on nails have increased as a mean of rapid and accurate biodosimetry. The most important outcome of these studies is the identification of a stable radiation-induced signal (RIS5) component in nails reported by the French Radioprotection and Nuclear Safety Institute (IRSN). The other important result is the dose determination protocol publicated in 2016 proposed by Sholom and McKeever funding from Dartmouth ESR center, with American National Institute of Health (NIH) funding. In this study, the results of three approaches on nail dosimetry were presented: two of them were based on the described protocols of IRSN and Dartmouth and the other used the classical dose addition method. Nail samples were collected from a donor irradiated with 137Cs gamma rays (0.5 kGy/h). ESR measurements were carried out using a Bruker e-scan X-band ESR spectrometer. Samples irradiated up to the doses of 25, 30, 85 and 168 Gy were 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 (Figures 1 and 4). To test last protocol published in 2016 (Darthmouth protocol), nail samples were irradiated by Co-60 gamma rays at 2 and 5 Gy as accidental radiation doses. The ESR signal intensities were recorded to use in formula given in proposed protocol. By using the first protocol, differences between dose saturation points of exposed and unexposed samples which determine the accident doses were found as 15 Gy for the first group and 10 Gy for the second group (Figures 2 and 3). On the other hand, by the second protocol, the ESR signal intensity increased with increasing added doses. The experimentally measured ESR signal intensity values fitted well by polynomial function and the extrapolated doses were calculated as 13.89 and 22.19 Gy for 10 and 15 Gy accident doses, respectively (Figures 5 and 6). Lastly, according to Dartmouth center protocol, the mean accident doses were calculated as 2.18 and 4.5 Gy for 2 and 5 Gy accident doses, respectively. In summary, IRSN protocol evaluating the RIS5 component and Dartmouth protocol were found to be successful methods for the evaluation of dose to nails exposed high-doses. However, classical approach using center field ESR signal given extrapolated doses in error of 38.9 and 47.9 percent was found to be unsuccessful for dose assessment by nails. Further studies should be planned to test the IRSN and Dartmouth approaches for lower accident doses on more samples from different individuals, taking attention to get results in short time.
In recent years, the number of Electron Spin Resonance (ESR) studies on nails have increased as a mean of rapid and accurate biodosimetry. The most important outcome of these studies is the identification of a stable radiation-induced signal (RIS5) component in nails reported by the French Radioprotection and Nuclear Safety Institute (IRSN). The other important result is the dose determination protocol publicated in 2016 proposed by Sholom and McKeever funding from Dartmouth ESR center, with American National Institute of Health (NIH) funding. In this study, the results of three approaches on nail dosimetry were presented: two of them were based on the described protocols of IRSN and Dartmouth and the other used the classical dose addition method. Nail samples were collected from a donor irradiated with 137Cs gamma rays (0.5 kGy/h). ESR measurements were carried out using a Bruker e-scan X-band ESR spectrometer. Samples irradiated up to the doses of 25, 30, 85 and 168 Gy were 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 (Figures 1 and 4). To test last protocol published in 2016 (Darthmouth protocol), nail samples were irradiated by Co-60 gamma rays at 2 and 5 Gy as accidental radiation doses. The ESR signal intensities were recorded to use in formula given in proposed protocol. By using the first protocol, differences between dose saturation points of exposed and unexposed samples which determine the accident doses were found as 15 Gy for the first group and 10 Gy for the second group (Figures 2 and 3). On the other hand, by the second protocol, the ESR signal intensity increased with increasing added doses. The experimentally measured ESR signal intensity values fitted well by polynomial function and the extrapolated doses were calculated as 13.89 and 22.19 Gy for 10 and 15 Gy accident doses, respectively (Figures 5 and 6). Lastly, according to Dartmouth center protocol, the mean accident doses were calculated as 2.18 and 4.5 Gy for 2 and 5 Gy accident doses, respectively. In summary, IRSN protocol evaluating the RIS5 component and Dartmouth protocol were found to be successful methods for the evaluation of dose to nails exposed high-doses. However, classical approach using center field ESR signal given extrapolated doses in error of 38.9 and 47.9 percent was found to be unsuccessful for dose assessment by nails. Further studies should be planned to test the IRSN and Dartmouth approaches for lower accident doses on more samples from different individuals, taking attention to get results in short time.
Description
Keywords
Nails, Tırnak, Biodosimetry, Biyodozimetri, Accident doses, Kaza dozları, ESR spectroscopy, ESR spektroskopi
Citation
Tepe Çam, S. (2020). Radiation dose determination by using nails with ESR biodosimetry technique. Turkish Journal of Nuclear Sciences, 32(1), 43-58.