Dept. of Biomath., California Univ. Sch. of Med., Los Angeles, CA.
IEEE Trans Med Imaging. 1990;9(4):439-46. doi: 10.1109/42.61759.
P.J. Green has defined an OSL (one-step late) algorithm that retains the E-step of the EM algorithm (for image reconstruction in emission tomography) but provides an approximate solution to the M-step. Further modifications of the OSL algorithm guarantee convergence to the unique maximum of the log posterior function. Convergence is proved under a specific set of sufficient conditions. Several of these conditions concern the potential function of the Gibb's prior, and a number of candidate potential functions are identified. Generalization of the OSL algorithm to transmission tomography is also considered.
P.J. Green 定义了一种 OSL（一步延迟）算法，该算法保留了 EM 算法的 E 步（用于发射断层成像中的图像重建），但提供了 M 步的近似解。OSL 算法的进一步修改保证了对数后验函数的唯一最大值的收敛性。在一组特定的充分条件下证明了收敛性。这些条件中有几个涉及吉布斯先验的势函数，并确定了一些候选势函数。还考虑了 OSL 算法在透射断层成像中的推广。
