Metals cause severe image artifacts in x-ray tomography, and accordingly a number of reduction approaches have been developed. We review our recently proposed metal artifact reduction (MAR) approaches for computed tomography (CT) that is computationally more efficient than a fully iterative reconstruction method, but at the same time achieves superior image quality to the interpolation-based in-painting techniques. Our proposed MAR method, an image-based artifact subtraction approach, utilizes an intermediate prior image reconstructed via pseudo-discrete algebraic reconstruction technique (PDART) to recover the background information underlying the high density objects. Additional approaches to tomosynthesis and other applications would be included in the conference presentations.