Retrospective EPR dosimetry in glass and tooth enamel – The methodology and results of MUG group in RENEB 2021 inter-laboratory comparison

Electron Paramagnetic Resonance (EPR) is recognized method in retrospective dosimetry, based on detection of stable paramagnetic centres induced by radiation in biological materials, like enamel, bones, nails, or artificial materials, like glasses and other. EPR dosimetry in glass and enamel were included, in addition to several biological dosimetry tests, in the recent intercomparison project Reneb ilc 2021 as one of the physical dosimetry methods potentially applicable for dose assessment in radiation accidents. EPR group from Medical University of Gdansk (MUG) was one of participants in this intercomparison. The participants reconstructed doses in three blinded samples of watch glass, Gorilla Glass from phone screens and in enamel irradiated with 0 Gy, 1.2 Gy and 3.5 Gy (these doses were revealed after reporting the final results by all participants). For reconstruction of doses in the glass sample the respective calibration samples were provided by organizers of the ILC project. For dosimetry in enamel the participants used their own calibration data. The doses reconstructed by us in the blinded samples (in terms of kerma in air) were: in watch glass: −0.05 Gy, 1.03 Gy, 3.16 Gy, in Gorilla Glass: −0.03 Gy, 1.20 Gy, 3.44 Gy, in enamel: 0.1 Gy, 1.3 Gy, 3.1 Gy. The differences between the reconstructed and the nominal doses were small and the accuracy was sufficient for triage of irradiated people at the level of 1–2 Gy. The small sample mass of the enamel, suitable rather to Q-band EPR dosimetry and potentially available without whole tooth extraction, allowed to obtain satisfactory accuracy of EPR dosimetry also in the X-band measurements.