Image Denoising Technique for CT Dose Modulation

Low-dose computed tomography (LDCT) imaging is considerably recommended for use in clinical CT scanning because of growing fears over excessive radiation exposure. Automatic exposure control (AEC) is one of the methods used in dose reduction techniques that have been implemented clinically comprise showing significant decrease scan range. The quality of some images may be roughly degraded with noise and streak artifacts due to x-ray flux, based on modulating radiation dose in the angular and slice directions. In 2005, the nonlocal means (NLM) algorithm showed high performance in denoising images corrupted by LDCT. The proposed method incorporates a prior knowledge obtained from previous high-quality CT slices to improve low-quality CT slice during the filtering process because of the anatomical similarity between the arranged image slices of the scans. The proposed method is evaluated using real data and CT image quality is notably improved.