Relaxed ordered subset preconditioned alternating projection algorithm for PET reconstruction with automated penalty weight selection

Purpose Performance of the preconditioned alternating projection algorithm ( PAPA ) using relaxed ordered subsets ( ROS ) with a non‐smooth penalty function was investigated in positron emission tomography ( PET ). A higher order total variation ( HOTV ) regularizer was applied and a method for unsupervised selection of penalty weights based on the measured data is introduced. Methods A ROS version of PAPA with HOTV penalty ( ROS ‐ HOTV ‐ PAPA )...