Applications of Film Tomography Technique for QNDE

Abstract

Tomography with X- and gamma- rays provides three-dimensional radiographic information on the examined object. The film-based tomography (1,2) generates a summation-image of a surface within the object by continuously combining back projections directly on the film. This method has many attractive features for industrial applications in which cost and simplicity are of primary importance. Some of the features are:

• (a) The absence of post processing allows this method to yield an image immediately on development of the film.

• (b) Conventional radiologists need a short training time to master the technique as most components and concepts are familiar to them: e. g. radiation sources, films, screens, collimators, filters, processing units, viewers, exposure, contrast, resolution.

• (c) Purpose oriented system optimized for a certain range of products, may be built with costs much less than digital computing trans-axial tomography (CT).

• (d) Tomographic images of surfaces of critical areas within the examined object are directly recorded on films curved to match the required shape.

• (e) Tomoaraphs on film may be digitized and imaged-processed by commercial system developed for conventional radiographs.

• (f) The slice thickness of the recorded surface may be in the order of magnitude of the thickness of the film-emulsion.

• (g) The quality of the tomograph is high especially for high- contrast objects (2) and whenever the noise and the dynamic-range of the film do not impose a limitation on the information to be extracted.