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North Bethesda, MD, United States

Romanyukha A.,Naval Dosimetry Center | Trompier F.,Institute for Radiological Protection and Nuclear Safety | Reyes R.A.,Uniformed Services University of the Health Sciences | Christensen D.M.,Oak Ridge Institute for Science and Education | And 2 more authors.
Radiation and Environmental Biophysics | Year: 2014

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. © 2014, Springer-Verlag Berlin Heidelberg (outside the USA). Source

Delzer J.A.,Uniformed Services University of the Health Sciences | Romanyukha A.,Naval Dosimetry Center | Benevides L.A.,Naval Dosimetry Center
Radiation Measurements | Year: 2011

An extensive study of neutron dose fading in LiF:Mg,Cu,P thermoluminescent dosimeters (TLD) using commercially-available dosimeters and equipment for their processing was undertaken. During the 52 week study, three thousand TLDs were stored for various lengths of time before and after being exposed to a plutonium beryllium radiation source. The TLDs were subsequently processed and the resulting doses were compared to the reference exposure. Both a loss of signal and a loss of sensitivity were evaluated. The results of this study have shown that the commercially produced LiF:Mg,Cu,P TLD has no statistically significant change in sensitivity or change in signal with up to 52 weeks of pre-irradiation or post-irradiation time. The results of this study will provide the technical basis for increasing the exposure record accuracy, and extending the usable lifetime of dosimeters. © 2010 Elsevier Ltd. All rights reserved. Source

Romanyukha A.,Naval Dosimetry Center | Trompier F.,Institute for Radiological Protection and Nuclear Safety | Reyes R.A.,Uniformed Services University of the Health Sciences | Melanson M.A.,Armed forces Radiobiology Research Institute
Radiation Measurements | Year: 2011

Results of a feasibility study for the use of the Q-band EPR measurements of fingernails are presented. Details of the first protocol developed for Q-band (34 GHz) EPR dose measurements in fingernails and preliminary results of a dosimetry study in comparison with the commonly-used X-band (9 GHz) are reported. It was found that 1-5 mg sample mass was sufficient for EPR measurements in fingernails in the Q-band, which is significantly less than the 15-30 mg needed for the X-band. This finding makes it possible to obtain sufficient fingernail sample for dose measurements, practically from every finger of any person. Another finding was that the spectral resolution of the mechanically-induced signal (MIS) and radiation-induced signal (RIS) in the Q-band was significantly better than in the X-band. The RIS and MIS in the Q-band spectrum have a more complex structure than in the X-band, which potentially offers the possibility to do dose measurements in fingernails without treatment and immediately after clipping. These findings and recent results related to fingernail dosimetry in the Q-band and its perspectives are discussed here. © 2011 Elsevier Ltd. All rights reserved. Source

Romanyukha A.,Naval Dosimetry Center | Trompier F.,Institute for Radiological Protection and Nuclear Safety | Reyes R.A.,Uniformed Services University of the Health Sciences
Radiation and Environmental Biophysics | Year: 2014

High-frequency Q-band (37 GHz) electron paramagnetic resonance (EPR) dosimetry allows to perform fast (i.e., measurement time <15 min) dose measurements using samples obtained from tooth enamel mini-biopsy procedures. We developed and tested a new procedure for taking tooth enamel biopsy for such dose measurements. Recent experience with EPR dose measurements in Q-band using mini-probes of tooth enamel has demonstrated that a small amount of tooth enamel (2-10 mg) can be quickly obtained from victims of a radiation accident. Accurate dose assessments can further be carried out in a very short time to provide important information for medical treatment. Here, the Q-band EPR dose detection limit for 5 and 10 mg samples is estimated to be 367 and 248 mGy, respectively. These values are comparable to the critical parameters determined for conventional X-band EPR in tooth enamel. © Springer-Verlag Berlin Heidelberg (outside the USA) 2014. Source

Reyes R.A.,Uniformed Services University of the Health Sciences | Trompier F.,Institute for Radiological Protection and Nuclear Safety | Romanyukha A.,Naval Dosimetry Center
Health Physics | Year: 2012

Previous studies have suggested that the electron paramagnetic resonance in fingernails can be used for radiation dosimetry purposes. Use of fingernails as an emergency dosimeter has benefits of easy, noninvasive sampling and fast dose measurements (∼10 min) potentially in field conditions and almost immediately after an exposure event. This study represents the next step in the development of EPR fingernail dosimetry; e.g., evaluation of the stability of the radiation-induced signal (RIS) at different storage and irradiation conditions. RIS fading during storage in both stressed (untreated) and unstressed (soaked in water) samples (n = 20) was studied at two temperature conditions: freezing (temp-20°C) and room temperature (20-24°C). Fingernail samples with the same clipping size and number and irradiated to 15 and 20 Gy were measured for over 200 d. Those irradiated to 100 and 200 Gy were measured for 114 d. The other group of samples irradiated to 1, 3, 8, and 20 Gy was followed for 25 mo of storage time. This study demonstrated that all samples that were kept at low freezing temperatures showed a stable RIS with no significant fading. All samples that were kept at room temperatures showed an initial fading of the signal with a slow rise of the EPR signal after irradiation with time to a saturation level. Obtained results allow making recommendations on the appropriate storage conditions of fingernails for EPR dosimetry use. Copyright © 2012 Health Physics Society. Source

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