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锥束CT 系统几何参数分析与校正
Release Time:28/08/2015






Analysis and Calibration of Geometric Parameters in

Cone-Beam CT System

Abstract: Aims to the engineering problem in Cone-Beam CT (Computed To- mography) reconstruction FDK algorithm that the geometric parameters of X-R ay source, turntable and the X-Ray planar detector cannot pinpoint exactly, we give a study of the effect of the geometric parameters of the system on reconstruct image through theoretical analysis and simulation experiment. Firstly, we boil them down to the error of X-Ray planar detector. Besides, we do some experiments to discuss the effects of each of the error on reconstruct image. The results indicate that: (1) the error rotation of the detector around center row or center column has little effects on the reconstruct image if it is enough little; (2) the distance from X-Ray source to the center of planar detector or to center of turntable plays a scaling part of reconstruct image; (3) the translation or rotation of detector in plane would cause serious ring artifacts. At last, we give the expression of the reconstruct formula with some typical error of system geometric parameters. We reconstruct the projection data of a model under the system geometric parameters error with it, the reconstruction results indicate that the proposed method can eliminate the artifacts and improve the quality of CB- CT image.

Keyword: Cone-Beam CT; Image Reconstruction; FDK; Geometric Calibration

1 前言

计算机层析成像技术(Computed Tomography简称CT)是利用射线穿过物体时,不同成分和厚度的物体对射线衰减程度不同的原理来成像。锥束CT的各种重建算法中,FDK算法由于其数学形式简单、计算效率高,且在锥角较小的情况下,能够取得较好的重建效果,因而在实际中有着广泛的应用。

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