CT imaging principle is through the X-ray on the human body tomography, and then through the computer processing of the image obtained. CT imaging, first of all through the X-ray on the need to examine the human body parts of the level of scanning, through the body of X-rays will be received by the detector, and then in the role of the photoelectric converter into electrical signals, in the role of the digital converter converted to digital signals, and then finally through the computer processing, rendered as a CT image. In CT, the digital matrix is a matrix of X-ray attenuation coefficients at selected levels, and the pixels are the gray-scale squares into which the numbers in the digital matrix are converted by the digital converter. In CT spatial resolution is the ability to display the smallest object, density resolution is the ability to distinguish the smallest density of tissue structure, and window position is the CT value of the center point of the gray scale on the CT image. CT examination should be well protected to avoid damage to the body caused by emission lines, and it is not recommended to perform multiple CT examinations in a short period of time, so as to avoid the accumulation of radiation in the body to affect the health of the body.