The most important developments in CT technology during the last half decade have been iterative reconstruction (IR) techniques, which have been applied to all major multidetector-row CT (MDCT) scanners and have created a new generation of reconstruction methods. Compared with conventional filtered-back projection (FBP) methods, IR is characterized by multiple iteration cycles during the reconstruction process until final output images are created and often enhances input images by using various statistical models. All major CT vendors have released their original IR techniques, which include Sinogram Affirmed Iterative Reconstruction (SAFIRE) and Advanced Modeled Iterative Reconstruction (ADMIRE) by Siemens Healthcare, Adaptive Statistical Iterative Reconstruction (ASIR) and Model Based Iterative Reconstruction (MBIR) by GE Healthcare, Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR3D) by Toshiba Medical Systems, and Iterative Model Reconstruction (IMR) by Philips Healthcare. Although the characteristics of these IR methods differ, it has been accepted that all of these IR methods can dramatically reduce image noise and improve image quality for chest CT.11–13