Beam-Hardening Correction Methods for Polychromatic X-Ray CT Scanners used to Characterize Structural Ceramics

Abstract

The use of medical computed tomography (CT) systems for inspecting industrial materials and components such as ceramics, which have higher mass density and electron density than one encounters in medical applications, is subject to difficulties such as beam hardening and scattering. Beam hardening (BH) occurs when polychromatic radiation is preferentially attenuated by the material as a function of photon energy. The BH effect prevents accurate measurement of local material density and causes artifacts that lower the sensitivity of contrast and spatial resolution. Because BH problems cause significant complications in image interpretation, a great deal of effort has gone into addressing this problem for medical applications. However, little effort has gone into developing BH corrections for industrial materials such as ceramics. The purpose of this paper is to present a BH correction method that takes into account both the photon spectrum of the X-ray head and the properties of ceramic materials. Scattering contributions to image degradation will not be considered here.