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.