Study of EPR/ESR Dosimetry in Fingernails as a Method for Assessing Dose of Victims of Radiological Accidents/Incidents
Uniformed Services University Of The Health Sciences Bethesda United States
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The threat of nuclear terrorism and the potential for the use of radiation as a weapon make having an efficient and accurate radiation dosimetry methodology paramount. Finger and toenails can efficiently be used as biomarkers in EPR dosimetry during a radiological emergency. EPR signals in these samples show a distinctively measurable radiation induced signal RIS but also show two other affecting signals, background BKS and mechanically induced MIS. This study addresses their effect, dose response improvements using chemical treatment, and the variability in dose-response. During the first stage of this study, a model that would explain the mechanical and dosimetric properties of human fingernails and an effective rapid sample water treatment were developed. This stage addressed the isolation of the MIS, BKS, and RIS, their origin, their evaluation under proposed treatment conditions, and treatment effect on dose dependence. The second stage evaluated these dosimetric properties in treated and untreated samples and assessed the variability in radiation response. This study gives a physicalmechanical explanation to the behavior of EPR signals in fingernail dosimetry by modeling fingernails as sponges. Since previous work wasperformed using stressed untreated samples, they do not represent the realistic behavior of unstressed treated fingernails. The developed treatment eliminates the combined effect of the mechanical EPR signals, MIS1 former MIS, and MIS2 former BKS. As nail samples are physically restored with treatments, are not stressed, and display a response closer to that of in vivo specimens. The RIS is proportional to the radiation dose and shows a curvilinear dose response in unstressed samples using the additive dose method that can be modeled with a saturating exponential model Grun model for predicting residual or accidental radiological dose.