Identification of 241Am in the Axillary Lymph Nodes With an Intrinsic Germanium Detector

Abstract

Abstract

A routine measurement with two 200 mm-diameter phoswich detectors, placed one each side of the sternum, yielded an apparent lung content of 17 nCi 241Am for a subject. Inspection of the data revealed that there were many more counts from the left side than from the right and that there was a greater number of Np L X rays observed, relative to the Lgamma ray, than would be expected for a uniform lung distribution of 241Am. These observations suggested a shallow localised deposit in the left side of the chest. The subject's working history could not rule out an inhalation exposure, but he was known to have had a wound contaminated with Pu/Am in his left hand 16 yr previously. The wound had contained approx. 0.02–0.03 μCi 241Am initially, most of which was excised from the wound site after 50 days. Prompted by this knowledge we used a 50mm-diameter intrinsic Ge detector to examine the wound and relevant lymph node sites. The results demonstrated a localised deposit of 241Am in the axillary lymph nodes with approx. 1 nCi 241Am at the wound site. Subsequent measurements made with the phoswich detectors suggested that there was approx. 7 nCi 241Am in the lymph nodes with approx. 1 nCi 241Am in the liver, thereby accounting for most of the detectable 241Am contamination in the thorax.