An alternative method using microwave power saturate in fingernail/electron paramagnetic resonance dosimetry

Zhao

Journal of Radiation Research

et al. 2016

Electron paramagnetic resonance (EPR) is a promising biodosimetric method, and fingernails are sensitive biomaterials to ionizing radiation. Therefore, kinetic energy released per unit mass (kerma) can be estimated by measuring the level of free radicals within fingernails, using EPR. However, to date this dosimetry has been deficient and insufficiently accurate. In the sampling processes and measurements, water plays a significant role. This paper discusses many effects of water on fingernail EPR dosimetry, including disturbance to EPR measurements and two different effects on the production of free radicals. Water that is unable to contact free radicals can promote the production of free radicals due to indirect ionizing effects. Therefore, varying water content within fingernails can lead to varying growth rates in the free radical concentration after irradiation—these two variables have a linear relationship, with a slope of 1.8143. Thus, EPR dosimetry needs to be adjusted according to the water content of the fingernails of an individual. When the free radicals are exposed to water, the eliminating effect will appear. Therefore, soaking fingernail pieces in water before irradiation, as many researchers have previously done, can cause estimation errors. In addition, nails need to be dehydrated before making accurately quantitative EPR measurements.

Section: Resultsmentioning

confidence: 99%

Effects of water on fingernail electron paramagnetic resonance dosimetry

Zhao

Journal of Radiation Research

et al. 2016

“…Another very promising use of physical dosimetry biodosimetry method is based on a dose dependent radiation-induced signal (RIS) in finger- and toenails as a means for estimating radiation dose, offering the additional advantage of accessing dose distribution in an individual. A large effort has been devoted to the analysis of the RIS in finger and/or toenail clippings (Trompier et al 2007, Romanyukha et al 2010, Choi et al 2014, He et al 2014, Romanyukha et al 2014b, Trompier et al 2014, Khailov et al 2015, Wang et al 2015, Marciniak and Ciesielski 2016, Tipikin et al 2016, Sholom and McKeever 2017). The ability of the clipped nail dosimetry method to estimate dose has been demonstrated in individuals receiving a high radiation dose due to accidental exposure (>10 Gy) (Romanyukha et al 2014b, Trompier et al 2014b).…”

Section: Introductionmentioning

confidence: 99%

“…The ability of the clipped nail dosimetry method to estimate dose has been demonstrated in individuals receiving a high radiation dose due to accidental exposure (>10 Gy) (Romanyukha et al 2014b, Trompier et al 2014b). Advancing these efforts into a rapid dosimetry method will require improvements in nail sample processing and instrumental innovations (Choi et al 2014, Wang et al 2015, Elajaili et al 2016, Marciniak and Ciesielski 2016) along with implementation of portable X-band EPR instrument platforms (Suzuki et al 2010, Romanyukha et al 2014b).…”

Section: Introductionmentioning

confidence: 99%

Developments in Biodosimetry Methods for Triage With a Focus on X-band Electron Paramagnetic Resonance In Vivo Fingernail Dosimetry

et al. 2018

Instrumentation and application methodologies for rapidly and accurately estimating individual ionizing radiation dose are needed for on-site triage in a radiological/nuclear event. One such methodology is an in vivo X-band, electron paramagnetic resonance, physically based dosimetry method to directly measure the radiation-induced signal in fingernails. The primary components under development are key instrument features, such as resonators with unique geometries that allow for large sampling volumes but limit radiation-induced signal measurements to the nail plate, and methodological approaches for addressing interfering signals in the nail and for calibrating dose from radiation-induced signal measurements. One resonator development highlighted here is a surface resonator array designed to reduce signal detection losses due to the soft tissues underlying the nail plate. Several surface resonator array geometries, along with ergonomic features to stabilize fingernail placement, have been tested in tissue-equivalent nail models and in vivo nail measurements of healthy volunteers using simulated radiation-induced signals in their fingernails. These studies demonstrated radiation-induced signal detection sensitivities and quantitation limits approaching the clinically relevant range of ≤ 10 Gy. Studies of the capabilities of the current instrument suggest that a reduction in the variability in radiation-induced signal measurements can be obtained with refinements to the surface resonator array and ergonomic features of the human interface to the instrument. Additional studies are required before the quantitative limits of the assay can be determined for triage decisions in a field application of dosimetry. These include expanded in vivo nail studies and associated ex vivo nail studies to provide informed approaches to accommodate for a potential interfering native signal in the nails when calculating the radiation-induced signal from the nail plate spectral measurements and to provide a method for calibrating dose estimates from the radiation-induced signal measurements based on quantifying experiments in patients undergoing total-body irradiation or total-skin electron therapy.

“…Hence, one of the major problems of EPR dosimetry in nails lies in how to extract the RIS from the experimentally measured signal. Several methods have been proposed to overcome this problem [11,24,34,[41][42][43][44]. However, for doses <10 Gy, all proposed methods to date have limitations due to the fact that in this dose range BKS is typically more intense than the stable RIS 5 and that BKS is known to be variable.…”

mentioning

confidence: 99%

EPR Dosimetry in Human Fingernails: Investigation of the Origin of the Endogenous Signal and Implications for Estimating Dose from Nail Signals

et al. 2022

Human fingernails have been studied for many years for potential use for dosimetry, based on the EPR signals induced by ionizing radiation, but a fully validated protocol to measure doses retrospectively has not yet been developed. The major problem is that the EPR spectrum of irradiated fingernails is complex and its radiation-induced signals ( RIS ) overlap with an endogenous signal called the background signal ( BKS ). RIS and BKS have similar spectral parameters. Therefore, detailed characterization of the BKS is required to develop a method for measuring the amount of RIS by removing the signal due to BKS from the total spectrum of irradiated fingernails. Effects of reducing and oxidizing treatments of fingernail samples on the BKS were studied. Numerical simulations of the observed BKS were performed. Common features of the EPR spectra in fingernails are discussed. We also found that BKS can be generated in the fingernail clippings by oxidation in ambient air with dioxygen. Results support the hypothesis that BKS is an o-semiquinone radical anion. Comparison of the chemical and spectral properties of the BKS and with the RIS 5 (the stable signal suitable for dose assessment) suggest that both sets of radicals underlying these signals are o-semiquinone radicals. Given the common chemical properties of the BKS and RIS 5, it is unlikely that chemical treatment methods will provide a means to differentiate these two signals in irradiated nail spectra. Instead, other methods (i.e. dose additive methods, population-derived BKS means) may be necessary to selectively estimate the content of BKS and RIS 5 in irradiated nail spectra.