beam geometry meaning in Chinese
波束几何形状
束几何
Examples
- Broad beam geometry
宽束几何条件 - In the terms of interpolation , the image reconstructed from nearest interpolation or linear interpolation has good edge but serious noise ; reconstruction from 4 * 4cubic interpolation or three b - spline or three - order lagrange interpolations has better local character . 2 x 2cubic interpolations which has both better edge and local character is the ideal interpolation , the following is the basic principle during reconstruction : ( 1 ) the more width of interpolation , the more number of summation and the more order of interpolation polynomial , the higher of density resolution ; ( 2 ) the more of interpolation polynomial and width of interpolation , the more of reconstruction time simultaneously , aimed at eliminating the effects of noise contained in projection data , in this paper , author analysis cause and effects of common artifacts . importantly , discusses convolution back - projection reconstruction algorithm with a shift axis of rotation has been derived for correcting images that acquired with a divergence axis of rotation using the fan beam geometry with an angle - equaled detector
在ct图像重建时，选择有限带宽窗有较好的空间分辨率，三角形窗有较好的密度分辨率，选择余弦窗则使得空间分辨率与密度分辨率的折衷；从窗函数的频谱角度来讲，可以用于图像重建的一个良好的卷积窗函数应该具备以下条件： ( ? )小的3db带宽b ，即最小的主瓣宽度； ( ? )最小的旁瓣最大峰值a ； ( ? )最大的旁瓣峰值衰减速度d ；就内插函数而言，临近点内插与线性内插重建图像噪声大，但有较好的边缘与细节； 4 4三次内插、三次b -样条与四次拉格朗日多项式内插图像平滑，局部特性较好。 - The simulation results show that , either for parallel geometry or for fan beam geometry , high resolution images can be reconstructed by means of both the algorithms from the overlapped projection data . moreover , the quality of the images reconstructed by the virtual detector algorithm from the overlapped low - resolution projection data is almost as good as that of the images reconstructed directly from the high - resolution projection data
大量模拟试验结果表明，无论对平行束的相叠低分辨数据还是对扇形束的相叠低分辨数据，用虚拟探测器法和直接重建法均可由相叠低分辨数据重建出具有较高分辨率的图像。