Keywords: plutonium incorporation, respiratory tract, lungs, internal dosimetry, radiation safety, radiation exposure, low radiation, dose estimation
Dosimetry of internal exposure of respiratory tract to incorporated plutonium
ICRP Publication 66 that had adopted a new approach to estimate dose to lungs and an extrathoracic region based on a revised human respiratory tract model was considered by the authors to address some aspects related to application of ICRP 66 in radiation safety practices. Comparison of committed equivalent doses received to the lungs following acute inhalation of plutonium-239 aerosols with different solubility and particle size calculated as per previous ICRP 30 approach (averaging of energy imparted by radiation to the organ over the mass of the organ) and new ICRP 66 concept (detriment-weighted dose resulting from irradiation of specific cells at risk in the lung) showed that these dose estimates are disparate. At the same time, ICRP 66 approach, being more biologically reasonable, still requires additional studies to validate risk apportionment among tissues in the lungs. Because ICRP 66 for the first time introduced a method to calculate internal radiation dose to the extrathoracic region, equivalent dose to this region following acute inhalation of different plutonium-239 aerosols was assessed in comparison with equivalent dose to the lungs. The relative contribution of the extrathoracic region to the effective dose turned out to be significant.