The Cases of Internal Contamination with 241Am

Full text: Up to present time, 14 people with intake of 241Am were measured by direct methods and also their excreta were analysed. Different approaches for the estimation of whole body content of 241Am were used. For the direct measurement, method of counting of 241Am in the skull is the most sensitive one. Introduction of this method for the routine in vivo measurements of the workers means that more cases with 241Am internal contamination were identified than before, when only simple whole body counting has been used. The most sensitive method is excretion analysis, which is, of course, quite time consuming. The interpretation of it is much more dependent on the assumed time of intake. Evaluation of the intake from the measurement in the skeleton is less dependent on the time of intake. It is not sensitive enough for monitoring of occupational exposure. This method is especially suitable for follow up of cases with old intakes. When higher inhalation intakes occur (both continuous and single accidental), combination of both approaches direct measurements in vivo and excretion analysis helps to estimate time of intake and enable to estimate committed effective dose in a realistic way. (author)