Low dose CT technique using prior image knowledge

In computed tomography (CT) imaging, radiation dose delivered to the patient is a major concern. It is particularly important when repeated scans occur for diagnostic or interventional purposes. In this paper, we compared two methods that can effectively reduce imaging radiation dose by use of the prior image knowledge, via reducing the number of projections for image reconstruction. In one method, we reconstructed the difference image between successive scans, and superimposed the difference image on to the prior image. In the other method, we masked the region in the image which is supposedly unchanging during the successive scans for image reconstruction. In both methods, we used a total variation (TV) minimization algorithm to reconstruct the images. We showed numerically that the first method outperforms the second one.