Robert N, Peyrin F, Yaffe M J
Department of Medical Biophysics, Sunnybrook Health Science Centre, University of Toronto, Ontario, Canada.
Med Phys. 1994 Dec;21(12):1839-51. doi: 10.1118/1.597223.
This paper describes a method to perform reconstruction of vascular cross-sectional images from a limited number of x-ray angiographic cone-beam projections. It is assumed that the projection data can be simplified by identifying blood vessels in each angiogram and removing signals due to other structures. Under these conditions, the x-ray attenuation coefficient, mu, can be modeled as a binary variable having a value mu 0 within the vessel and "0" outside. The reconstruction is performed by minimizing a cost function using the method of simulated annealing. In this paper, we demonstrate that the introduction of a priori information allows one to reconstruct a sphere and a simulated branched vessel from three views with, respectively, 97% and 93% of voxels having correct values. The addition of a continuity constraint for the reconstruction of the branched vessel resulted in further reduction in the percentage of misplaced voxels. Calculations require from one to six hours of CPU time on a Sun SparcStation 2 computer for the cases investigated here. The effect of noise, "cooling" schedule, and number of views on the reconstruction are examined using simulated vessel projections. Modifications to our approach to accelerate the reconstruction are also discussed.
本文描述了一种从有限数量的X射线血管造影锥束投影进行血管横截面图像重建的方法。假定通过识别每个血管造影中的血管并去除其他结构产生的信号，可以简化投影数据。在这些条件下，X射线衰减系数μ可建模为一个二元变量，在血管内取值为μ0，在血管外取值为“0”。使用模拟退火方法通过最小化代价函数来进行重建。在本文中，我们证明引入先验信息能够分别从三个视图重建球体和模拟分支血管，重建后分别有97%和93%的体素具有正确值。为分支血管重建添加连续性约束导致误置体素的百分比进一步降低。对于此处研究的案例，在Sun SparcStation 2计算机上进行计算需要1到6小时的CPU时间。使用模拟血管投影来研究噪声、“冷却”时间表和视图数量对重建的影响。还讨论了对我们的方法进行修改以加速重建的问题。
