CT of the lower abdomen does not allow for a complete view of the intestines and is still deficient for the duodenum and transverse colon. The intestinal structure of the human body consists mainly of the small intestine and the large intestine. The small intestine starts from the pylorus of the stomach at the upper end, and is divided into the duodenum, jejunum, and ileum at the lower end, followed by the cecum. The large intestine is the lower part of the alimentary canal, with a total length of about 1.5m, surrounding the jejunum and ileum throughout, and can be divided into five parts: the cecum, appendix, colon, rectum and anal canal. Lower abdominal CT is mainly for the examination of the organs in the lower abdomen. Since the intestine is located in the lower abdomen, it can help to examine the intestine at the same time when performing CT examination. Due to the distribution of the intestinal tract, lower abdominal CT can be used to observe the rectum, sigmoid colon, ascending colon and descending colon, and is relatively insufficient for the observation of the transverse colon and duodenum. Lower abdominal CT examination, if there are obvious intestinal lesions can be seen. Inflammation and ulceration of the intestinal mucosa cannot be accurately determined. The examination should be performed under the supervision of a physician.