Clinical application of radiation dose reduction at abdominal CT.

Report VII of the Board on Radiation Effects Research (BRER), in which the linear no-threshold hypothesis was applied, estimates the lifetime carcinogenesis risk from computed tomography (CT) as 0.34 to 1.30%. Other studies provided evidence for breaks in double-stranded lymphocyte DNA in human blood during CT examinations. Although it cannot be claimed that such DNA damage is a direct cause of carcinogenesis, it is important to reduce the radiation exposure of patients subjected to CT studies. Here we focus on techniques and clinical applications of abdominal reduced-dose CT. With automatic exposure control (AEC), the X-ray tube current can be optimized and the noise level maintained uniformly, regardless of the target size. Iterative reconstruction can reduce the image noise on scans acquired at reduced radiation doses. Use of these techniques helped to reduce radiation exposure at routine examinations by about 20-40%. We also discuss advanced imaging methods such as dynamic perfusion CT.