Shadow Zone Padding Method for Grangeat Reconstruction of Circular Cone-Beam CT

Abstract

通过分析圆轨迹锥束CT(cone-beam CT,简称CBCT)扫描Radon域的数据缺失问题,比较了前人提出的Radon阴影区域数据缺失填充方法的特点,提出了一种基于距离权重变量的阴影区域填充方法.该方法采用阴影区域边界数据作为数据源,以距离作为权重函数计算填充数据.计算机模拟重建实验表明,所提出的方法在填充数据准确度、减少伪影、大锥角图像重建等方面比简单的常数填充法以及衍生算法效果更好.该填充方法特别适用于Grangeat类锥束CT重建算法,拓展了圆周锥束CT的实际应用范围.;Based on the analysis of the shadow zone and the padding methods of the Radon domain generated by circular cone-beam CT scanning, this paper proposes a shadow zone padding method by distance-weighted interpolation. The method uses the known boundary data to interpolate the missed data inside the shadow zone with a distance weighting function. Simulation results show that the proposed padding method shows some advantages over the constant padding technique in terms of data-padding accuracy, artifacts reduction and image reconstruction for large cone-angle cone-beam scanning. The data padding method is particularly useful in Grangeat reconstruction algorithm. It enlarges the applicable scope of circular cone-beam tomography.