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Proceedings Paper

Algorithm to correct for z-detector gain variations in multislice volumetric CT
Author(s): Guy M. Besson; Hui Hu; Min Xie; H. David He; Neil Bromberg; George Seidenschnur
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Paper Abstract

This paper presents a calibration and correction method for detector cell gain variations. To provide variable slice thickness capability in multislice volumetric scanners, while minimizing costs, it is necessary to combine the signals from several detector cells. The process of combining the output of several detector cells with non-uniform gains can introduce numerical errors when the impinging x-ray signal varies over the range of the combined cells. These scan dependent numerical errors can lead to artifacts in the reconstructed images, particularly when the numerical errors vary from channel-to-channel. A projection data correction algorithm has been developed to subtract the associated numerical errors. For effectiveness and data flow reasons, the algorithm works on a slice-by-slice basis. An initial error vector is calculated by applying a high-pass filter to the projection data. The essence of the algorithm is to correlate that initial error vector, with a calibration vector obtained by applying the same high-pass filter to various z-combinations of the cell gains. The solution to the least-square problem gives the coefficients of a polynomial expansion of the signal z-slope and curvature. From this information, and given the cell gains, the final error vector is calculated and subtracted from the projection data.

Paper Details

Date Published: 28 May 1999
PDF: 12 pages
Proc. SPIE 3659, Medical Imaging 1999: Physics of Medical Imaging, (28 May 1999); doi: 10.1117/12.349491
Show Author Affiliations
Guy M. Besson, General Electric Medical Systems (United States)
Hui Hu, General Electric Medical Systems (United States)
Min Xie, General Electric Medical Systems (United States)
H. David He, General Electric Medical Systems (United States)
Neil Bromberg, General Electric Medical Systems (United States)
George Seidenschnur, General Electric Medical Systems (United States)

Published in SPIE Proceedings Vol. 3659:
Medical Imaging 1999: Physics of Medical Imaging
John M. Boone; James T. Dobbins III, Editor(s)

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