The 2019–2020 EURADOS WG10 and RENEB Field Test of Retrospective Dosimetry Methods in a Small-Scale Incident Involving Ionizing Radiation

Abstract

With the use of ionizing radiation comes the risk of accidents and malevolent misuse. When unplanned exposures occur, there are several methods which can be used to retrospectively reconstruct individual radiation exposures; biological methods include analysis of aberrations and damage of chromosomes and DNA, while physical methods rely on luminescence (TL/OSL) or EPR signals. To ensure the quality and dependability of these methods, they should be evaluated under realistic exposure conditions. In 2019, EURADOS Working Group 10 and RENEB organized a field test with the purpose of evaluating retrospective dosimetry methods as carried out in potential real-life exposure scenarios. A 1.36 TBq 192 Ir source was used to irradiate anthropomorphic phantoms in different geometries at doses of several Gy in an outdoor open-air geometry. Materials intended for accident dosimetry (including mobile phones and blood) were placed on the phantoms together with reference dosimeters (LiF, NaCl, glass). The objective was to estimate radiation exposures received by individuals as measured using blood and fortuitous materials, and to evaluate these methods by comparing the estimated doses to reference measurements and Monte Carlo simulations. Herein we describe the overall planning, goals, execution and preliminary outcomes of the 2019 field test. Such field tests are essential for the development of new and existing methods. The outputs from this field test include useful experience in terms of planning and execution of future exercises, with respect to time management, radiation protection, and reference dosimetry to be considered to obtain relevant data for analysis.

RENEB/EURADOS field exercise 2019: robust dose estimation under outdoor conditions based on the dicentric chromosome assay

“…Therefore, in addition to ILCs under controlled laboratory conditions, field exercises that more closely resemble a real-life exposure are required to test the validity of different methods for retrospective dosimetry, to identify logistic problems and to test the ability of network members to provide valid results. The EURADOS/RENEB field exercise performed in Lund, Sweden in October 2019 simulated a small-scale exposure scenario by irradiating four phantoms placed in different geometries to a 1.36 TBq 192 Irsource (Waldner et al 2020). The phantoms were equipped with a variety of materials to perform biological and physical retrospective dosimetry, including blood samples used for the assessment of doses based on the DCA.…”

“…The current exercise was planned and performed in cooperation by EURADOS WG10 and RENEB in Lund, Sweden in October 2019, to resemble a small scale exposure scenario of a few individuals, exposed in different geometries, to test the ability of the different assays alone or in combination to resolve the exposure types as well as the relevant doses (Waldner et al 2020). In comparison to standard ILCs performed under controlled laboratory conditions, this exercise was a field test, to more closely resemble a real-life scenario, where exposure conditions and logistical aspects are much more difficult to control than in the laboratory.…”

“…In comparison to standard ILCs performed under controlled laboratory conditions, this exercise was a field test, to more closely resemble a real-life scenario, where exposure conditions and logistical aspects are much more difficult to control than in the laboratory. In total four anthropomorphic phantoms were equipped with several materials that were used for retrospective physical and biological dosimetry (Waldner et al 2020).…”

“…All phantoms (P1-P4) were positioned on chairs at a height of 45 cm. Details about the source, dose rates, phantoms and irradiation conditions can be found in Waldner et al 2020. For biological dosimetry purposes each phantom was equipped with 2 thermos flasks (Primus Trailbreak, 550 ml) filled with water at approximately 37 °C.…”

“…A detailed description of the RPL glass dosimeters used for this field test can be found in (Waldner et al 2020). For the purpose of biological dosimetry, RPL glass dosimeters were placed in a sealed vinyl bag for the measurements performed inside thermos flasks filled with warm water and on the external surface of the thermos flasks.…”