Burgess A E
Med Phys. 1977 Jan-Feb;4(1):21-5. doi: 10.1118/1.594297.
The effect of asymmetric focal spots in blood vessel imaging is investigated by computer simulation. Phase distortion effects are studied in isolation from MTF effects. Calculations are done for a number of symmetric and asymmetric foci with identical standard deviations. It is concluded that blood vessel image degradation due to focus asymmetry per se is small and that the LSF standard deviation is a useful size parameter for both symmetric and asymmetric foci.
通过计算机模拟研究了非对称焦点在血管成像中的效果。相位失真效应是与调制传递函数（MTF）效应分开研究的。对许多具有相同标准差的对称和非对称焦点进行了计算。得出的结论是，焦点不对称本身导致的血管图像退化很小，并且线扩散函数（LSF）标准差对于对称和非对称焦点都是一个有用的尺寸参数。
