Identification of 241Am in the axillary lymph nodes with an intrinsic germanium detector.

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. 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 L gamma 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 mu Ci 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.