For localized irradiation to hands, in case of sources accidentally
handled, it is very difficult to estimate the dose distribution by
calculation. Doses may reach several tens of grays, and the dose
distribution is usually very heterogeneous. Until recently, doses in
such situations could be estimated only by analysis of bone biopsies
using Electron Paramagnetic Resonance (EPR) spectroscopy. This technique
was used previously on surgical wastes or after amputation of a finger.
In this case, the dose information was available in one or a few
locations on the hand only, due to the limited number of biopsy
fragments usually collected. The idea to measure free radicals (FRs)
induced by radiation in nails to estimate a dose is not new, but up to
now, no application cases were reported. As a matter of fact, the EPR
analysis of nails is complex due to the presence of intrinsic signals
and parasitic signals induced by the mechanical stress (when nails are
collected), which overlaps the radio-induced components. In addition,
the radio-induced FRs identified up to now are unstable and very
sensitive to humidity. In these conditions, it was difficult to foresee
any application for dosimetry with fingernails. Recently, stable
radio-induced FRs in nails has been identified and an associated
protocol for dose assessment developed. This protocol has been applied
by the Institut de Radioprotection et de Sûreté Nucléaire on fingernail
samples from victims of three different radiological accidents that
occurred between 2008 and 2012 in different places.