“…According to this principle, reducing the total variation of the signal subject to it being a close match to the original signal, removes unwanted detail whilst preserving important details such as edges. Stimulated by the theory of compressive sampling or compressive sensing (CS) [1], [2], the sparsity based computed tomography (CT) has been a hot topic for various applications such as dose reduction [3]. Because the x-ray decrease coefficient often varies gently within an anatomical component, and large changes are usually confine around borders of anatomical structures, the discrete gradient transform (DGT), a set of finite difference operators, has been widely utilized as a sparsifying action in CS-inspired CT reconstruction such as in, whose L1-norm is also referred to as the total variation (TV) [4], and the equivalent reconstruction techniques are called TV minimization.…”