Manufactured specimens with complex and irregular shapes which include internal structures (e.g., turbine blades) are often difficult to inspect with most NDE techniques.  Radiographic Computerised Tomography (CT) provides a powerful inspection tool, enabling 2D cross-sectional images of the specimen to be produced. However, standard x-ray CT tomographic methods require thousands of projections, each regularly distributed over 360° to produce an accurate image. The large number and the regularity of projections result in lengthy data acquisition times which are further exacerbated by the number of components to be inspected (e.g., Rolls-Royce can produce over 2000 turbine blades a week).  

The ever increasing power of computers and the advents of graphics card processors mean that a variety of limited view imaging techniques are now viable methods of generating high quality images with less data. These limited view algorithms therefore provide an opportunity to significantly reduce acquisition time for CT inspection, enabling much faster inspection and reducing the pressure to purchase multiple CT systems to increase throughput. More efficient use of CT systems can significantly reduce costs.

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Figure 1: Comparison of a 2D slice through a turbine blade reconstruction using the industry standard and a limited view algorithm. Note the significant difference in the number of projections necessary by the limited view algorithm in order to obtain a high quality image of the turbine.