Attenuation in the Chest Wall of 20 keV X-rays from an Inhaled Radioactive Aerosol

Abstract

EXTERNAL counting of the low intensity L uranium X-rays (energies 13.6, 16.9 and 20.2 keV) is a promising technique for the estimation of insoluble compounds of plutonium in the human lung. These low energy radiations are, however, very easily absorbed in the tissues of the chest wall; the half-value thickness (HVT) is about 0.7 cm of soft tissue and only 0.03 cm of bone. The effects of variations in body build are clearly important and difficult to assess, and calibration of the counting equipment is a severe problem. One approach has been the use of a phantom¹ or cadaver². In neither of these cases is there any certainty that the radiation from plutonium inserted into the chest cavity will undergo the same attenuation by surrounding tissues as in vivo.