Validation of a Dose Assessment Method to be Used in 18F FDG Loose Contamination Exercises

Radiological emergency response may require responders to operate in contaminated environments. To provide more realistic training to these individuals, it has been proposed to disperse low amounts of short-lived radioactive material in simulated emergency scenarios. To demonstrate the applicability and safety of such activities, a limited exercise was conducted where 18F was sprayed in a small area and survey activities were executed. A pre-job external radiation exposure dose assessment was performed in preparation for this training. The research presented here compares participant external recorded doses to assessment results in order to validate the dose estimates. Two individuals were used during the dispersion, search, and survey activities. First, a radiation worker mixed 200 MBq Fludeoxyglucose 18F with 470 mL H2O in a weed sprayer and distributed it over a 3 m × 3 m area. After evaporation, an exercise participant performed search and survey activities in the area. Actual whole-body doses measured with optically stimulated luminescence dosimeters were 10 ± 1 μSv for both personnel. Whole-body digital dosimeters read 4.3 ± 0.2 μSv and 3.3 ± 0.5 μSv for the radiation worker and exercise participant, respectively. Actual extremity doses were below the dosimeters' minimum detectable limits for the radiation worker (thermoluminescence dosimeter) and exercise participant (optically stimulated luminescence dosimeter). The dose assessment-predicted whole-body doses were 2.8 ± 0.4 μSv and 3.2 ± 0.1 μSv for the radiation worker and exercise participant, respectively. The estimated dose to the radiation worker's hand was 21.8 ± 3.8 μSv, and the estimated dose to the exercise participant's knee was 13.4 ± 0.6 μSv. The study provided substantial evidence for the validity of the dose assessment method, supporting its use for a larger training exercise.