Method for Numeric Estimation of Cupping Effect on CT Images

摘要

Usage of common reconstruction algorithms like Filtered Back Projection and Algebraic Reconstruction Techniqueto the projection data acquired with poly-chromatic probing radiation leads to the appearance of a cup-like distortion ofthe value profile in reconstructed images. While many methods of the poly-chromatic probing artifacts suppression aresuggested, the numerical estimation algorithm of the “Cupping effect” typically is not considered to be important.Described methods imply manual regions selection where the intensity will be compared, or just use experts’ opinion onthe effect presence. In this paper, we suggest automatic estimation of the “Cupping effect” method based on utilizing thedistance transform built using the objects mask. As a result, we obtain a numeric estimation of the intensity change fromthe border to the center of the object. As the final image index, a weighted sum of the ratings of all objects is used. Whilepositive value shows the magnitude of the “Cupping effect”, a negative value, on the contrary, shows magnitude of thereverse “Cupping effect”. In the paper, we demonstrate the method used on simulated data and compare it with severaldifferent techniques for distortion evaluation due to poly-chromatic probing. Finally, we show method effectiveness onreal data acquired with laboratory tomography.