Patent ID: 6411671
Filing Date: 2002-06-25
Classification: G01N,G06T

Abstract:
A method for reducing line artifacts in a CT image D1, acquired by scanning an examination subject by rotating at least a focus of an X-ray source around the examination subject and detecting radiation, attenuated by said examination subject, with a detector system which has a plurality of proper detector channels and at least one defective detector channel, and wherein said CT image D1 is subjected to an interpolated filtering for preventing or correcting faulty values of picture elements represented on a circle K1, said faulty values being caused by the defective detector channel, comprising the steps of:(a) subjecting picture elements of the CT image D1 to a median filtering, orthogonal to a straight line extending through the respective picture element and a center of the circle K1, for producing an image M1; (b) forming a difference value image F1=D1âˆ’M1 by subtracting the image M1 from the CT image D1; (c) producing two resulting images G11 and G21 by filtering picture elements of the difference value image F1 in respective directions of tangents t11 and t21 to the circle K1 extending through the respective picture element, whereby the filtering is conducted along t11 for the resulting image G11 and is conducted along t21 for the resulting image G21; and (d) forming a correction image D2=D1âˆ’G11âˆ’G21 by subtracting the resulting images G11 and G21 from D1.