Possibilities of Transmission Radiation Tomography and Tomography Based on Backscattered Radiation

Abstract

In order to improve fabrication technologies, it is necessary to develop means for monitoring with high accuracy and high information content. Using the existing means it is diffi cult to prevent emergency situations in nuclear power, aerospace engineering, chemical and oil-and-gas industries, machine building, and metallurgy. New innovative and promising methods are required. Introscopy and industrial radiation computer tomography are such means.Transmission computer tomography is based on obtaining (reconstructing) an image of the interior structure of an object from a collection of projection data measured at different aspects. Computer processing of this data array using special software makes it possible to obtain a picture of the transverse section of the monitored object, represented in the density distribution of the material in the monitored section [1][2][3][4].The possibilities of monitoring industrial objects by means of introscopy with radionuclides have been demonstrated for articles of aerospace engineering (Figs. 1-3).The following are possible applications of the method: 1) monitoring the quality and state of parts in motors, elements of electric, pneumatic, and hydraulic systems, nozzles, and power elements;2) optimizing technology for fabricating structural materials; 3) investigation of the reasons for accidents in subassemblies and assemblies; 4) radiography of parts and subassemblies; 5) correctness of installation of assemblies and detection of foreign objects; 6) density distribution of materials and heavy metals; and 7) separation of composite materials. For nozzles in the apogeal acceleration motors of space vehicles, computer tomography has been shown to be expedient for detecting separation and determining the density of the material [1,4]. The samples investigated were 100-200 mm in diameter cylindrical parts. The parts had a matrix comprised of elements containing carbon. The degree of permeation of the matrix by metals was different in different samples. The problem was to determine the distribution of these metals along a layer of the sample. The density distribution along the cross section of the part (see Fig. 3) was obtained from tomograms of a nozzle before and after tungsten permeation of the matrix.In order to distinguish objects in fi ber-optic communication lines, the interior structure of the objects must be monitored. Radiation computer tomography solves these problems successfully. It can reveal the arrangement of optical fi bers and cable parts in the objects. A tomogram of a cable is displayed in Fig. 4; it was obtained by using the radionuclide source 137 Cs without processing and with an x-ray source with voltage 400 kV on the tube and processing.