Comparison of the elemental composition of normal and diseased human tissues by PIXE analysis

The proton beam from a 4 MV Van de Graaff accelerator has been used in conjunction with a Si(Li) detector system to perform elemental analysis of biological samples by proton-induced X-ray emission (PIXE). Dried tissue samples from a number of different organs were analyzed; including kidney, lung, liver, colon, breast, larynx, and aorta. For each organ, two specimens were taken of the same cellular type: normal tissue and diseased tissue. Therefore, a direct comparison of the effect of the disease state on the elemental composition could easily be obtained. For the aorta sets the disease state studied compared tissue from atherosclerotic lesions to normal aorta tissue while for the other organs, a sample of cancerous tissue was compared to a healthy tissue. The present results show a marked decrease in the Cd concentration as well as for the Se and Pb, when present, for the malignant kidney tissue compared to the normal one. It is found that the Zn/Cu ratio also decreases for all malignant kidney cases. Preliminary results indicate the same trend for this ratio for the colon and liver but an increase for the breast, larynx, and lung sets. Except for Br and Cu, the aorta sets show a general increase in all elements, particularly for Ca and Sr, when the lesion tissue is compared to the normal aorta tissue. (Auth.)