改进的多层螺旋CT线性插值算法

Improved linear interpolation algorithm for multi-slice helical CT

线性插值是多层螺旋CT的基础重建算法之一,基本原理是搜寻重建平面上下2组投影数据进行插值,而搜寻数据及计算权重函数过程会大大降低重建效率。该文提出了一种改进的适用于一定螺距范围的线性插值算法,以4层螺旋CT为例,给出了不同探测器排投影数据的权重函数,可直接用于插值计算,从而提高重建效率。通过模拟三维Shepp-Logan头部模型投影数据,验证了该算法的重建效果和适用范围。结果表明:该算法在中小螺距范围内重建效果好,图像还原能力高,在保证重建图像质量的同时,拥有较大的体积覆盖率,可用于需要快速重建的情况。

Linear interpolation （LI） is one of the basic reconstruction algorithms for multi slice helical CT （MSCT） which searches for the upper and lower projection data sets adjacent to the reconstructed slice for interpolation. However, the searching for the data and computing the weighting function significantly reduces the reconstruction efficiency. An improved LI method was developed for a range of helical pitches with a 4-slice helical CT as an example. The algorithm defines the projection data weighting function from different detector rows, which can be used directly for interpolation to increase the reconstruction efficiency. The 3D projection data for the Shepp-Logan head phantom was simulated to verify the reconstruction capability and the applicable range of this method. The results show that this method does well for moderate and small helical pitches. The image restoration capacity is very good and the volume coverage is quite fast with good image quality. This method can be used in situations requiring fast reconstruction.