Monte Carlo dosimetry for a EURADOS WG 10 and RENEB field test of retrospective dosimetry techniques in realistic exposure scenarios

Computational dosimetry using Monte Carlo radiation transport simulations was applied for the 2019 European Radiation Dosimetry Group (EURADOS) and Running the European Network of Biological and retrospective Physical dosimetry (RENEB) field test, an exercise of retrospective dosimetry techniques for a realistic small-scale radiological accident. The simulations were performed at four institutes, using different codes and computerized anthropomorphic phantoms. Four exposure scenarios using Ir-192 were modeled: relatively homogeneous in a predominantly AP direction, heterogeneous in a predominantly anterior-posterior (AP) and left-lateral (LLAT) direction, and partially shielded. The items for dosimetry, such as mobile phones, blood tubes, and surface dosimeters, were designed and located based on the experimental pictures. Absorbed doses of dosimeters, such as thermoluminescence dosimeter (TLD), optically stimulated luminescence dosimeters (OSLD), radio-photoluminescence dosimeters (RPLD), and display glasses, inside and outside the phantoms were calculated and compared to the measured doses. In addition, photon energy spectra were calculated at different locations to correct the energy responses of the materials. The simulation results from the four institutes showed agreement with each other, showing an average relative difference of less than 14%. The Pearson's R-values for the linear fitting of the measured and calculated data ranged from 0.95965 to 0.68714, depending on the exposure scenario and institutes. Finally, the accuracy and limitations of the calculation techniques for the given exposure structures are discussed.