Abstract: During the last decades, CT has become the predominant imaging technique in the diag-nosis of diseases. However, given the high radiation sensitivity in children, CT scanning should be indicated extremely carefully. These CT related parameters such as CT dose index, dose-length product, layers and areas can be controlled to decrease pediatric patients exposure doses. To ensure the quality of CT images clear, tube current, tube voltage and pitch can also be controlled to decrease exposure doses. Children exposure doses could be evaluated through the measurement of the effective dose and collective does. Using CT in children patients should be on the basis of the radiation protection of the three principles.