Computed tomographic (CT) route has much superior diagnostic accuracy in different clinical circumstances in comparison to other chest radiography. Although argumentative, contemporary data acquiesce that medical radiation exposure increases significantly the risk effects of contrary radiation. A number of CT routines sophisticated to reduce radiation dose, however, preserving image quality. The standard CT reconstruction algorithm Filter back projection techniques (FBP) cannot produce diagnostic quality images combined with a reduction of x-ray tube currents expressed in (mA). The main objective of the presented study is to estimate the influence of Adaptive Statistical Iterative Reconstruction (ASIR) algorithm on dose reduction and images quality on Computed tomography (CT) Chest with non-contrast and contrast examination compared with the traditional FBP technique.