An experimental study on the influence of scatter and beam hardening in x-ray CT for dimensional metrology

Lifton, J., Malcolm, A.A. and McBride, J (2015) An experimental study on the influence of scatter and beam hardening in x-ray CT for dimensional metrology. Measurement Science and Technology, 27 (1), 1-12. (doi:10.1088/0957-0233/27/1/015007).

Abstract

Scattered radiation and beam hardening introduce artefacts that degrade the quality of data in x-ray computed tomography (CT). It is unclear how these artefacts influence dimensional measurements evaluated from CT data. Understanding and quantifying the influence of these artefacts on dimensional measurements is required to evaluate the uncertainty of CT-based dimensional measurements. In this work the influence of scatter and beam hardening on dimensional measurements is investigated using the beam stop array scatter correction method and spectrum pre-filtration for the measurement of an object with internal and external cylindrical dimensional features. Scatter and beam hardening are found to influence dimensional measurements when evaluated using the ISO50 surface determination method. On the other hand, a gradient-based surface determination method is found to be robust to the influence of artefacts and leads to more accurate dimensional measurements than those evaluated using the ISO50 method. In addition to these observations the GUM method for evaluating standard measurement uncertainties is applied and the standard measurement uncertainty due to scatter and beam hardening is estimated.

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Contributors

Author: J McBride

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