For many years, the dominant reconstruction method for CT images has been the analytical method filtered back projection (FBP). Thanks to improved computer capacity iterative reconstruction (IR) has come to increasingly replace FBP. The iterative algorithms have the ability to incorporate statistical models and models of the CT system that aim to improve the image quality. The iterative procedure can be performed in various ways and the various manufacturers have chosen different approaches. Thus, it is of interest to study if there are different strengths and weaknesses. Above all, it is interesting to study the difference between the different generations of algorithms: statistical- and model-based IR algorithms. With phantom measurements, the potential of improve image quality has been evaluated for different algorithms. It was demonstrated that the new image reconstruction algorithms have great potential to decrease radiation dose and improve image quality. Clinical trials in humans are planned.