Image analysis, modeling, enhancement, restoration, feature extraction and their applications in nondestructive evaluation and radio astronomy : Zheng, Yi. Dissertation Abstracts International, Vol. 49, No. 2, pp. 507 (Aug. 1988)

Abstract

This study aims at establishing X-ray methods for inspection of cast aluminium components by combining two approaches, a radioscopic inspection, and a photon-counting system.Indeed, radioscopy is widely used in castings inspection for automatic defect detection and is an efficient method for characterising rather small thicknesses, typically less than 40 mm. However, cast components often show a high range of thicknesses and imaging the whole range is difficult. We propose to use photon-counting measurements to complement the radioscopic image for high thicknesses. Photon-counting is not an imaging tool, but the thickness sensitivity obtained from photon-counting measurements (number of X-ray photons transmitted through the object) is much better than what can be obtained by classical radioscopy for up to 60 mm of aluminium. For high thicknesses of aluminium, within small volumes where defects are believed to be critical, the photon-counting system allows getting information additional to that obtained from classical radioscopy images.