Combination of liquid scintillation counting and passive sampling strategy for the determination of ¹³¹I in air and application to estimate the inhalation dose to the staff of a nuclear medicine service.

(131)I, commonly used in nuclear medicine, can be incorporated into the human body in a variety of chemical and physical forms. This study describes a sensitive method for the determination of (131)I concentration and its application to the estimation of the amount of airborne (131)I inhaled by staff workers of a Nuclear Medicine Department. Our method uses passive sampling with charcoal canisters followed by liquid scintillation counting, a very sensitive technique for the determination of low concentrations of airborne (131)I. We have studied the effects caused on the measured (131)I concentration in air by both, the doses administered to the patients and the distance of sampling canisters to the patient. We have found a direct relationship between the amount of (131)I activity administered and the airborne (131)I activity concentration. We have estimated the contribution of inhaled (131)I to the effective dose received by staff, finding differences between physicians and non-physician personnel. However, the measured exposure was quite low in both cases, thus suggesting that there is no need to introduce additional safety measures to the current ones.