NEUTRON ACTIVATION ANALYSIS IN THE STUDY OF PULMONARY DISEASE: THE USE OF AN ATOMIC REACTOR AS A LABORATORY INSTRUMENT

Abstract

A neutron activation method, as applied to the detection of foreign elements in human lung, is described; results relating to findings of As, Sb, and Si are reported and its use for detection of other elements outlined. Fresh specimens of lung tissue were placed in polyethylene vials and kept in the frozen state until analysis. The vials were then placed in methylmethacrylate tubes and inserted in the rotary specimen rack of the reactor. A standard sample of the element being studied was irradiated at the same time. For As the reaction is: As/sup 75/(n, gamma )As/sup 76/ (half-life 26.7 hr). Exposure of samples to a neutron flux of 1.8 x 10/sup 12/ N/cm/sup 2// sec provides saturation limits of detection of 0.005 Vg As. In this case, specimens and a standard solution containing 1 g As were irradiated for 1 hr at 250 kw. The specimens were then withdrawn from the reactor and stored overnight in appropriate Pb shielding in order to allow for the decay of Na and Cl. The chemical separation of metallic As is outlined in detail. The results of analysis of cancerous and noncancerous lung in smokers and nonsmokers for As by low beta counting suggestmore » relative concentration of As in trace amounts by neoplastic or inflamed lung tissue without relation to tobacco use. Antimony, coprecipitated with As in the analysis, was also present in increased amounts in the neoplastic tissue but not in uninvolved lung. Other elements, that can be quantitated by neutron activation analysis and the limits of their detectability are listed. By this technique it was also possible to exclude the diagnosis of silicotuberculosis in a patient with a known industrial exposure to SiO/sub 2/. The significant advantages to the method are extreme sensitivity, freedom from reagent contamination, relative speed, and, in some cases, nondestructive analysis of the sample. (TCO)« less