Johnson E L, Wang H, McCormick J W, Greer K L, Coleman R E, Jaszczak R J
Duke University Medical Center, Department of Radiology, Durham, NC 27710, USA.
Phys Med Biol. 1996 Aug;41(8):1439-52. doi: 10.1088/0031-9155/41/8/012.
Filtered backprojection is commonly implemented as a pixel driven algorithm in which the density is reconstructed on an array of grid points that are usually associated with the centres of square image pixels. In fan beam geometry, this conventional pixel driven approach using two-bin linear interpolation leads to an inefficient use of the projection data due to magnification at the projection line. For typical count limited SPECT data, this results in increased reconstructed image noise. We propose an alternative type of pixel driven algorithm that makes efficient use of projection data by averaging over all bins within a position dependent "effective' projection bin interval. The effective bin interval is equivalent to the image pixel length magnified on the projection line. This heuristic method leads to more complete use of the projection data and results in reconstructed images with superior noise properties compared with the conventional method while presenting similar spatial resolution characteristics.
滤波反投影通常作为一种像素驱动算法来实现，在该算法中，密度是在一组网格点上重建的，这些网格点通常与方形图像像素的中心相关联。在扇形束几何结构中，这种使用双区间线性插值的传统像素驱动方法，由于投影线上的放大作用，会导致投影数据的低效利用。对于典型的计数受限单光子发射计算机断层扫描（SPECT）数据，这会导致重建图像噪声增加。我们提出了一种另类的像素驱动算法，该算法通过在位置相关的“有效”投影区间内的所有区间上进行平均，有效利用投影数据。有效区间等效于投影线上放大的图像像素长度。与传统方法相比，这种启发式方法能更充分地利用投影数据，从而得到具有更好噪声特性的重建图像，同时呈现出相似的空间分辨率特征。
