CT of the lower abdomen is mainly for the organs in the lower abdomen, and since the intestines are located in the lower abdomen, it can help to examine the intestines at the same time when performing CT examinations. CT examination of the lower abdomen is mainly used to observe the rectum, sigmoid colon, ascending colon and descending colon, and is relatively lacking for the observation of the transverse colon. CT examination of the lower abdomen for the intestine is only able to observe the morphological problems of the intestine, and has a preliminary diagnostic role for tumor diseases and surrounding lymph node enlargement. However, for some people, intestinal diseases are caused by inflammation and ulcers in the intestinal mucosa, which cannot be observed by CT examination, and lower abdominal CT examination can only observe whether there are tumors in the intestine, but cannot judge the benign and malignant nature of tumors. In order to determine whether the tumor is malignant, biopsy should be performed under colonoscopy to determine.