In vivo counting of americium-241 in human lungs and tracheobronchial lymph nodes

Graduation date: 1987To distinguish americium-241 in human lungs from\ud translocated activity in the tracheobronchial lymph\ud nodes (TBLN), two intrinsic germanium detectors were\ud collimated with 0.3-cm lead sheeting.\ud A tissue-\ud equivalent phantom containing either 620 nCi (22.9 kBq)\ud in the lungs or a 2200 nCi (81.4 kBq) TBLN point source\ud was counted; as chest wall thickness increased, net\ud count rate per unit activity generally decreased\ud exponentially for two of three counting positions.\ud Phantom calibration curves were compared to data\ud obtained by the same detection system for a human male\ud with a known lung deposition of 2.4 nCi (88.8 Bq) of\ud americium-241.\ud The relation of the data to the\ud calibration curves indicated the activity was restricted to the lungs.\ud If activity had translocated to\ud the\ud smaller TBLN, the specific dose would\ud have increased and\ud the TBLN might have been designated\ud the critical organ. Footnote: This research\ud was supported by the Northwest\ud College and University Association for\ud Science\ud (University of Washington) under Contract\ud DE-AM06-76-RL02225 with the U. S. Department\ud of Energy